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https://ntrs.nasa.gov/search.jsp?R=19800010714 2020-03-21T20:03:58+00:00Z
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DOE/NASA/0078-79/1 NASA CR-159650 WMB&A 4500-131-3-R1
STUDY OF ADVANCED ELECTRIC PROPULSION SYS'TEM CONCEPT USING A FLYWHEEL
~~ FOR ELECTRIC VEHICLES i::I" C~
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~ Francis C. Younger ~ Heinz Lackner o ~ William M. Brobeck & Associates
December 1979
Prepared for NATIONAL AERONAUTICS AND SPACE ADMiNISTRATION Lewis Research Center Under Contract DEN 3-'18
for U.S. DEPARTMENT OF ENERGY Conservation and Solar Applications Office o'fTransportation Programs
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NOTICE
This report was prepared to document work sponsored by the United States Government. Neither the United States nor its agent, the United States Department of Energy, nor any Federal employees, nor arty of their contractors, subcontractors or their employees, ~mkes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, produ~t or "","(".ess disclosed, or represents that its use would not : i;" - 'l'ge privately owned rights.
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DOE/NASA/0078-79/1 NASA CR-159650 WMB&A 4500-131-3-R1
STUDY OF ADVANCED ELECTRIC PROPULSION SYSTEM
CONCEPT USING A f'l YWHEEL FOR ELECTRIC VEHICLES
Francis C. Younger Heinz Lackner William M. Brobeck & Associates Berkeley, California 94710
December 1979
Prepared for National Aeronautics and Space Administration Lewis Research Center Cleveland, Ohio 44135 Under Contract DEN 3-78
for U.S. DEPARTMENT OF ENERGY Conservation and Solar Applications Office of Transportation Programs Washington, D.C. 20545 Under Interagency Agreement EC-77-A-31-1 011
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PREFACE
The Electric and ~iybrid Vehicle Research, Development, and Demonstration Act of 1976 {Public Law 94-413} authorized a Federal program of research and development designed to promote electric and hybrid vehicle technologies. The Energy Research and Development Administration, now the Department of Energy {DOE}, which was given the responsibility for implementing the Act, established the Electric and Hybrid Vehicle Research, Development, and Demonstration Project within the Division of Transportation Energy Conservation to manage the activities required by Public Law 94-413.
The National Aeronautics and Space Administration under an Interagency Agreement (Number EC-77-A-31-1044) was requested by ERDA (DOE) to undertake research and development of propulsion systems for electric and hybrid vehicles. The Lewis Research Center was made the responsible NASA Center for this project. The study presented in this report is an early part of the Lewis Research Center program for propulsion system research and development for electric vehicles.
The research described in this report was conducted under Contract DEN3-78 with the National Aeronautics and Space Administration (NASA) and sponsored by the Department of Energy through an agreement with NASA.
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CONTENTS
Page
PREFACE . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1. ABSTRACT . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
2. INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. OBJECTIVE . . . . . . . . . . . . . . . . . . . . . . . . . . 5
4. TASK DESCRIPTIONS . . . . . . . . . . . . . . . . . . . . . 7
5. REQUIREMENTS . . . . . . . . . . . . . . . . . . . . . . . . . 9
6. PRELIMINARY ANALYSIS . . . . . . . . . . . . . . . . . . . . . . 13s
6.1 Methodology . . . . . . . . . . . . . . . . . . . . . . 13
6.2 General Concepts . . . . . . . . . . . . . . . . . . . . 14
6.3 Characteristics of Traction Motors . . . . . . . . . . . . . 19
6.4 Characteristics of Controllers . . . . . . . . . . . . . . . 30
6.5 Characteristics of CVTs . . . . . . . . . . . . . . . . . . 33
6.6 Characteristics of Flywheels . . . . . . . . . . . . . . . . 35
6.7 Characteristics of Driveline . . . . . . . . . . . . . . . . 40
6.8 Performance Comparisons . . . . . . . . . . . . . . . . . . 40r
6.9 Other Factors . . . . . . . . . . . . . . . . . . . . . . . 42
6.10 Recommended Candidates for Task II . . . . . . . . . . . . . 51
7. DESIGN TRADE-OFF STUDIES . . . . . . . . . . . . . . . . . . 53
7.1 Design Parameters Studied . . . . . . . . . . . . . . . 53
7.2 Control Modes . . . . . . . . . . . . . . . . . . . . . . . 69
7.3 Energy Management . . . . . . . . . . . . . . . . . 69
7.4 Performance Comparisons . . . . . . . . . . . . . . . . 79
7.5 Cost Comparison . . . . . . . . . . . . . . . . . . . 79
7.6 Candidates Recommended for Conceptual Design . . . . . . . . 79
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8. CONCEPTUAL DESIGN . , . . . . . . . . . . . . . . . . . . . . . . 83
8.1 System Voltage and Semiconductor Types . . . . . . . . 83
8.2 Description of Concept A6 . . . . . . . . . . . . . . . . . 85
8.2.1 Current Waveforms and !Harmonic Losses . . . . . . . . 05
8.2.2 Control Circuits . . . . . . . . . . . . . . . . . . 94
8.2.2.1 Slip Controller . . . . . . . . . . . . . . 94
8.2.2.2 Traction Motor Three-Phase Generator . . . . 99
8.2.2.3 Gear Shift Controller . . . . . . . . . . . 99
8.2.2.4 Rotor, Vehicle, and Flywheel Tachometer . . 99
8.2.2.5 Flywheel Mode Control . . . . . . . . . . 100
8.2.2.6 Flywheel Controller . . . . . . . . . . . 100
8.2.2.7 Flywheel Three-Phase Generator . . . . . . . 100
8.2.2.8 Flywheel Motor/Generator Position Sensor . . 100
8.2.2.9 Power Supply . . . . . . . . . . . . . . . . 101
8.2.2.10 Drive Electronics . . . . . . . . . . . . . 101
8.3 Description of Concept D2 . . . . . . . . . . . . . . . . 101
8.4 Flywheel,Size and Energy Rating . . . . . . . . . . . . . . 108
8.5 CVT Types . . . . . . . . . . . . . . . . . . . . . . . . . 110
8.6 Vehicle Performance . . . . . . . . . . . . . . . . . 110
8.7 Propulsion System Cost Comparison . . . . . . . . . . . 114
9. DISCUSSION OF RESULTS . . . . . . . . . . . . . . . . . . 117
10. CONCLUSIONS . . . . . . . . . . . . . . . . . . . . . . . . 121
11, RECOMMENDATIONS . . . . . . . . . . . . . . . . . . . . . . 123
12. REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . 125
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APPENDICES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129
Appendix A - Advanced Electric Vehicle Propulsion System,Design Concept A6 . . . . . . . . . . . . . . . . . 131
Appendix B - Advanced Elect .,,i Vehicle Propulsion System,Design Concept: D2 . . 4, . . . . . . . . . . . . . . 155
Appendix C - Models for Propulsion System Components . . . . . . 175
Appendix D - Guidelines and Back-up Information for CostCalculations . . . . . . . . . . . . . . . . . . 191
Appendix E - Computer Flow Chart and Program . . . . . . . . . . 203
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LIST OF FIGURES
Figure No. Title Page
1 SAE Electric Vehicle Driving Cycles SAE J227a . . . . 12
2 General Concept "A" . . . . . . . . . . . . . . . . . 15
3 General Concept "B" . . . . . . . . . . . . . . . . . 16
4 General Concept "C" . . . . . . . . . . . . . . . . . 17
5 General Concept "D" . . . . . . . . . . . . . . . 18
6 Torque-Speed Characteristics of Electric Motors . 21
7 Chopper Circuit for DC Motors . . . . . . . . . . . . 22
8 Performance Characteristics of DC Motor . . . . 24
9 Equivalent Circuit of Induction Motor . . . . . . . . 26
10 Circle Diagram for Induction Motor . . . . . . . . 27
11 Torque vs. Speed at Various Power Factors . . . . . . 28
12 Performance Characteristics of AC Motor . . . . . . . 29
13 Simplified Chopper Circuit for DC Motor withRegeneration Capability . . . . . . . . . . . . . . . 31
14 Electronically Commutated DC Motor. . . . . . . . . 32
15 Inverter for 3-Phase Induction Motor, . . . . . . . . 34
f' 16 Velocity Loss Due to Creep . . . . . . . . . . . . . 36i 17F Effect of Normal Load on Spinning Torque & Creep Slope 37
18 Flywheel Stored Energy vs. Flywheel Speed . . . . . 39
19 Candidate A6, AC Motor Drive , . . . . . . . . . 54E
20 Candidate A8, Electronically Commutated DC MotorDrive . . . . . . . . . . . . . . . . . . . . . . . . 55
4. 21 Candidate D2, DC Drive Motor and CVT . . . . . . . . 56
22 Candidate D4, AC Drive Motor and CVT . . . . . . . . 57
23 Candidate B5, Two AC Motors/Direct Drive . . . . . 58
24 Driveline Efficiency vs. Range . . . . . . . . . . . 62
25 Battery Weight vs. Range with Lead Acid Batteries 67
26 Concept A8. Flywheel/Battery Current-AccelerationDependent . . . . . . . . . . . . . . . . . . . . . . 74
27 Concept A8. Battery Leveling . , . . . . . . . . . . 75
28 Concept A8. Preset Maximum Positive & NegativeCurrent Limit . . . . . . . . . . . . . . . . . 76
29 Design Concept A6 . . . . . . . . . . . . . . . . . . 87E
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Voltage Waveform From Inverter , . . . . . . . . . . . 89
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LIST OF FIGURES (Continued)
Figure No.
31
32
33
34
35
36
37
38
39
40
Title
Equivalent Circuit of Induction Motor . . . . . . .
Simplified Inverter Circuit . . . . . . . . . . . . .
A6 Control Circuit Diagram . . . . . . . . . . . . .
ConceptD2 . . . . . . . . . . . . . . . . . . . .
Power Flow - Candidate D2 . . . . . . . . . . . . .
Timing for Semiconductor Switches for Nine-PhaseMotor. . . . . . . . . . . . . . . . . . . . . .
Electronic Commutation Switches for Nine-Phase Motor.
Electronically Commutated Motor Switches . . . . . .
Flywheel Stored Energy vs. Flywheel Speed . .. . . .
Flywheel/Generator Unit . . . . . . . . . . . . . .
Page
90
95
97
103
104
106
107
109
111
112
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LIST OF TABLES
` Table No. Title Page
1 Task Descriptions . . . . . . . . . . . . . . . . . . 8
2 Advanced Electric Vehicle Performance Requirementsand Cost Goals . . . . . . . . . . . . . . . . . 10
3 Electric Vehicle Characteristics . . . . . . . . . . 11
4 Battery Characteristics . . . . . . . . . . . . . . . 11
5-8 Characteristics of Candidate Propulsion Systems . . . . 41,43-45
9 Performance of Candidate Propulsion Systems . . . . . . 46
10 Advantages and Disadvantages of Power Systems . . . . . 48
C 11 Technology Advances Required . . . . . . . . . . . . 49
12 Loss Coefficients Used in Driveline . . . . . . . . . . 60
13 Concept A6. Transaxle Losses . . . . . . . . . . . . 61
14 Summary Table of Peak Motor Power Requirements . . . . 63
15 AC Induction Motor Analysis for Various Slips andPower Factors . . . . . . . . . . . . . . . . . . . . . 64
16 SAE J227a Schedule D Cycle Range Obtained for MotorsListed in Table 15 . . . . . . . . . . . . . . . . . . 65
17 Battery Weight vs. Range . . . . . . . . . . . . . . . 66
18 Battery Weight vs. Range . . . . . . . . . . . . . . . 68
19 Control Modes . . . . . . . . . . . . . . . . . . . . 70
20 Range vs. Various Transmission Ratios . . . . . . . . . 71
21 Shift Point Evaluation . . . . . . . . . . . . . . . . 72
22-23 Energy Management Scheme Evaluation . . . . . . . . . . 77,78
24 Candidate Weight/Performance Comparison . . . . . . . . 80
25 Candidates - Propulsion System Cost Comparison. . . . . 81
r26 General Vehicle Specification - Design Concept A6 . . . 86
27 Harmonic Amplitudes of Pulsed Wave . . . . . . . 91
28 Leg Voltage and Current Associated with Harmonicsof Pulsed Wave at Maximum Torque . . . . . . . . . . . 92
29 Losses Per Leg Associated with Harmonics of PulsedWave at Maximum Torque . . . . . . . . . . . . . . 93
30 General Vehicle Description Design Concept D2 . . . . 102
31 Candidate Weight/Performance Comparison . . . . . . 113
32 Propulsion Systems - Cost Comparison . . . . . . . 115
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1. ABSTRACT
A study for evaluation of advanced electric propu'ision system concepts
with flywheels for electric vehicles predicts that advanced systems canprovide considerable performance improvement over existing electric pro-pulsion systems with little or no cost penalty. Using components speci-
fically designed for an integrated electric propulsion system avoids thecompromises that frequently lead to a loss of efficiency and to inefficient
utilization off,
space and weight. A propulsion system using a flywheel
energy storage device can provide excellent acceleration under adverseconditions of battery degradation due either to very low temperatures orhigh degrees of discharge. Both electrical and mechanical means of transferof energy to and from the flywheel appear attractive; however, developmentwork is required to establish the safe limits of speed and energy storage
for advanced flywheel designs ai''s to achieve the optimum efficiency ofenergy transfer. Brushless traction motor designs using either electronic
commutation schemes or do-to-ac inverters appear to provide a practicalapproach tj a mass producible motor, with excellent efficiency and light
weight. No comparisons were made with advanced system concepts which do not
incorporate a flywheel.
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2. INTRODUCTION
This study is intended to identify and evaluate advanced propulsionsystem concepts for on-the-road electric vehicles. Electric vehicles areof interest because their use will reduce petroleum consumption and
pollution. Today about one half of the petroleum consumed in the United
States is used for transportation. The introduction of electric vehiclescould significantly shift the transportation energy base to other sourcessuch as coal, nuclear, and solar.
Most electric passenger cars built in recent years have been con-versions of conventional automobiles using available do motors withvarious control schemes.
The availability of vehicles, motors and control devices rather than
optimum energy efficiency and performance often dictated the nature ofthe propulsion system design. With the evolution of a new generation ofelectric vehicles for passenger use, specially-design components willpresumably be used. If a new generation of electric vehicles is to be
mass produced for a potentially large market, the components for thesevehicles should be tailored to meet the specific requirements of an
automotive market. The criteria for weight and efficiency would notnecessarily be those for the industrial motor and controller nor for air-
craft motors, but would aim to meet the vehicular needs of light weight,low cost and high efficiency.
The study was to select from several proposed concepts, 'two conceptsthat have a range of 100 miles over the J227a D cycle (ref. 1) and also meet
performance standards set by NASA using battery characteristics givenby NASA. Conceptual designs of these two concepts were then to beprepared.
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3. OBJECTIVE
The objective of the study is to identify attractive concepts for
advanced propulsion systems that offer considerable performance improve-ment over existing propulsion systems with little or no potential costpenalty.
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4. TASK DESCRIPTIONS
The program effort was organized into four main tasks as shown inTable 1. In the first task, Preliminary Analysis, a variety of candidatepropulsion systems were evaluated using the performance requirements fora four passenger vehicle assuming the use of an improved state-of-the-art(ISOA) lead-acid battery. It was also assumed that advanced componentswould be available for an engineering model by 1983. Components assumedavailable in this time frame include high-speed light-weight traction motorsdesigned specifically for electric vehicles, advanced semiconductorcontrollers for these motors, high-specific-energy flywheels, and light-weight continuously-variable-transmissions (CV1'). Task 1 also includes
an assessment of the technology advancements required to yield the compo-nents and system integrations for the advanced propulsion systems.
In the second task, Design Trade-Off Studies, the most attractivecandidates are subjected to a more detailed analysis to determine optimumsizes and ratings of system components, optimum operating points and operatingmodes to achieve the required performance considering energy consumption,battery life and life cycle cost.
In the third task, Conceptual Design, layout drawings for the twomost attractive concepts are to be prepared showing the location of allcomponents within possible vehicle configurations. Consideration is to begiven to cost, effective component operation, maintainability, reliability,and passenger safety and comfort. Performance and life cycle costs of theseconceptual designs are to be estimated.
In the fourth major task, Development Plan, the required effort fordevelopment of the conceptual designs will be assessed. This task isto identify all major developmental efforts for each new technologyrequirement. The plan is to cover the effort required up to and includingfabrication and laboratory testing of an engineering model of the advancedpropulsion system. Work on this task was submitted as a preliminary draft.
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Table 1. Task Descriptions
Task Flo. Description
1 Preliminary AnalysisEvaluate general Concepts and recommend
five for Task 2
2 Design Trade-Off StudiesOptimize and evaluate specific concepts
3 Conceptual Design
Prepare conceptual designs of two con-cepts
4 Development Plan
Identify major activity areas andestimate required effort
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5. REQUIREMENTS
Advanced concepts for evaluation are envisioned as propulsion systemswhich can be developed in about five years using advanced technologies thatare projected to produce components with lower weight and higher efficiencythan current state-of-the-art components. These systems are expected toinclude flywheel energy storage devices not presently available to boost thepeak power to give improved performance of electric vehicles.
The purpose of the study is the conceptual design of two advancedelectric propulsion systems with the objective of meeting the cost andperformance requirements listed in Table 2, when tho propulsion system isinstalled in an electric vehicle with characteristics as listed in Table3 using a battery with characteristics as listed in Table 4.
The requirements are taken to apply at the test weight of the vehicleat an ambient temperature of 27 00 and for a new traction battery. The testweight is taken as the curb weight of the vehicle plus 300 pounds (136 kg).
In addition to the requirements given in Table 1, effort to minimizethe effect on performance and operation due to o battery degradation andoperating temperature extremes of -29 C to +52 C. The propulsion system isto be designed to optimize the battery available energy and battery life.
The driving cycles for evaluating electric vehicles are those specifiedby SAE J227a which lists four different test schedules. The characteristicsof these schedules are summarized in Figure 1. Different schedules areused for different types of vehicles. The schedule "D" is the one to beused for evaluating advanced electric vehicles. The range for an electricvehicle operating repeatedly over the SAE J227a cycles is determined bythe point where the vehicle can no longer satisfy the acceleration at thestart of the cycle.
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Table 2. Advanced Electric VehiclePerformance Requirements and Cost Goals
Min. Range, SAE J227a Schedule D, km (mi) 161 (100)
Min. Range at constant 72 km/h (45 mi/h), km (mi) 209 (130)
Max. acceleration time 0-89 km/h (0-55 mi/h), seconds 15
Max, merging time, 40-89 km/h (25-55 mi/h), seconds 10
Min. passing speed, km/h (mi/h) 105 (65)
Sustained speed on an uphill 4% grade, km/h (mi/h) 89 (55)
Ramp speed. Min. attainable from a stop on an uphill6% grade in 305 m (1000 ft), km/h (mi/h) 65 (40)
Maximum wall plug energy for SAE J227a, Schedule D 559 kJ/km (250 W-H/mi)
Minimum life 161,000 km (100,000/mi)
Maximum life cycle cost (propulsion system plus $.05/km ($.08/mi)battery only)
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Table 3. Electric Vehicle Characteristics
Base weight, kg (lbs)
Maximum payload, kg (lbs)
Test load, kg (lbs)
Weight propagation factor
Tire radius, mm (in)
Aero drag coefficient times Area, C dA, m2 (ft2)
Air density, O (sec 2 lbs )
m 3ft4
Rolling resistance coefficients
CoNon-dimensional
C sec (sec)1 m ft
C sec (sect)2 m2 ft
Rotational inertia factor non-dimensional
326 (718)
272 (600)
136 (300)
1.299
292.1 (11.5)
.56 (6)
1.26 (2.38 x 10-3)
8 x 10-3
3.599 x 10 -5 (1.097 x 10-5)
1.036 x 10 -6 (9.63 x10-8)
1.04
Table 4. Battery Characteristics
Lead Acid Nickel-Zinc
Specific energy wh/kg 40 80
Specific power w/kg 100 150
Cycle life (80% discharge) 800 500
Cost $/kWh 50 75
Efficiency % 60 704
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6. PRELIMINARY ANALYSIS
The characteristics and performance of 28 candidate propulsionsystems were analyzed. These candidates covered a variety of componenttypes and arrangements and included ac and do traction motors withand without multi-speed transmissions. All candidates included a flywheelstorage system to provide load levelling for the battery and to give apower boost for acceleration and an energy sink for use in regenerativebraking. Single and dual axle drives were considered.
A computer program which calculates the energy consumption ofelectric vehicles in any driving cycle was used to help evaluate thecandidate systems. Preliminary studies of component types were madeto establish the characteristics and data which were input to thecomputer program. Special subroutines were prepared to generate performancecharacteristics of various components. CVTs and electrical controllerswere modeled on the basis of known losses. Motor types were modeledusing equivalent circuit concepts and theoretical relationships for knownlosses.
6.1 Methodology
The method for analysis of propulsion system candidates was iterativein nature using a computer simulation of the specific driving cycles.Specifications of components were set initially at values believed tobe adequate to satisfy performance requirements. These were then usedas input for the computer with the various driving cycles set to simulateall the required performance goals. Component sizes and ratings werealtered as required to satisfy all the power requirements. Battery weightwas varied to meet the range requirements. Resulting vehicle weights, energyconsumption and range were used as figures of merit for assessing the relativeattractiveness of each of the candidates. In addition to the computer analysis,preliminary evaluations of technology risks and other factors were made. Themost attractive concepts without excessive risks were identified for furtherstudy in design trade-off studies.
The computer program, Appendix E, calculates all of the energy lossesfor the driving cycle on a second-by-second basis. The subroutines forthe various motor types permits a direct calculation of copper and ironlosses, bearing friction and windage. The motor subroutine for acinduction motors uses the equivalent circuit for induction motor andcalculates the air gap magnetic flux required to produce the necessarycounter emf. The do motor subroutine calculates the required field coilexcitation current and magnetic flux using a typical reluctance circuitand the magnetic saturation characteristics of a laminated iron used inmotor construction.
13
Losses in the motor controller were separately calculatedat each time step to find the efficiency of these units.
Axle and transmission losses due to gear friction, bearing frictionand windage were also calculated at each time step rather than using afixed efficiency for these units. The losses for multi-speed transmissionsvaried with the gear ratio.
Run-down losses for the flywheel were included in the calculation.The in-and-out efficiency of the flywheel storage system with its controllerlosses were also included.
6.2 General Concepts
The propulsion system for an electric vehicle can be very simple.An electric motor can be mechanically coupled to the drive wheels and thebattery can be electrically connected to the motor by a simple controlcircuit. The electric motor draws current from the battery to providepropulsion power to drive the vehicle. Some means of controlling thepower to the drive wheels is necessary to control the vehicle speed. Avariety of different types of motors and their control is possible. Varyingdegrees of complication evolve around the control schemes for differenttypes of motors and driveline components. High efficiency, light weightand easy handling are obviously desirable. Separately excited do motorscan be controlled by field weakening over a large speed range. The use ofa transmission extends the vehicle speed range without a correspondingincrease in motor speed range. Some vehicles also use chopper control ofarmature current to extend the range of motor controlability.
For the envisioned automotive market the nature of the design would besuch as to favor those designs more susceptible to mass production and lowmaintenance. Mechanically commutated do motors would appear to be lessattractive than squirrel cage induction motors or electronically commutateddo motors. However, the controller for such motors could have complications,weights and costs that would more than offset any savings due to thesimpler motor construction. The trade-off between cost and efficiencywould not merely be judged in terms of the cost of energy saved but wouldrather consider the increase in range and increase in battery life.
Various general concepts using a variety of motor types and driveconfigurations have been proposed for preliminary analysis. All of theseuse a flywheel for a power booster to provide a power boost foracceleration and to maintain acceptable performance even on a nearlydischarged battery or under adverse temperature conditions. The arrangementof the driveline components are shown in Figures 2, 3, 4, and 5.
These four general configurations represent different drivelinepower flow paths using different elements.
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In general Concept A a single traction motor drives the vehicle withor without a transmission. Electrical energy for the traction motor comesfrom two sources, the battery and the flywheel storage system. The nature ofthe energy converters depends upon the type of traction motor used. Themotor types considered for this general concept are three-phase ac inductionmotors and electronically commutated do motors. The flywheel energy bufferconsists of a flywheel coupled to a generator which converts the flywheelkinetic energy to electrical energy. To recharge the flywheel, the generatormust run as a motor, thus, suitable motor types for coupling to the flywheelare those which can function both as a generator and as a motor over a widespeed range. Electronically commutated do motors with field control appearto be most suitable for this purpose. The high speed of the flywheel drivemotor requires a brushless design to minimize friction and run-down losses.Two types are considered for the preliminary analysis; one with permanentmagnets for the field and the other with wound field coils. Permanentmagnet motors are somewhat simpler than wound field machines and requireno excitation current; however, the absence of controllable field coilslimits the means of voltage control. The inability to weaken the fieldprevents the desirable reduction of eddy current and hysteresis losses duringcruising and coasting periods where flywheel power is not required.
General Concept B differs from General Concept A primarily in havingtwo traction motors. It seemed possible that two smaller electric motorscould give better efficiency than a single larger motor because one couldbe turned off to eliminate some of the losses which lead to reducedefficiency at light loads. Two motors would be used for acceleration andbraking and a single motor used during cruise and other light load conditions.As with General Concept A this general concept covers variations havingdifferent motor types, with and without multi-speed transmissions.
General Concept C employs two traction motors as does General ConceptB, but uses two drive axles on the grounds that better recovery of energyvia regenerative braking may be possible with this arrangement. Thisgeneral concept also covers a range of motor types, with and without multi-speed transmissions.
General Concept U is similar to General Concept A in having a singletraction motor, but instead of using an electrical conversion of flywheelkinetic energy a mechanical conversion utilizing a continuously variabletransmission (CVT) is used. Torque output of the flywheel is directlyrelated to the rate of change of the flywheel's angular momentum which canbe controlled by the rate of change of the CVT speed ratio. For thisconcept to be practical requires a light-weight CVT with high efficiency.It is believed that such a device can be developed.
6.3 Characteristics of Traction Motors
The evaluation of the performance of any motor in a propulsion systemis made in terms of its torque/speed characteristics and its losses.
19
Many different types of motors can !e considered as possible tractionmotors for advanced electric propulsion systems. For such an applicationthe motor should have high efficiency and be light weight and inexpensive.It should be easily controlled when used with batteries as the main sourceof energy.
Over the years, there has been a steady growth in the improvement ofthe design of electric motors to take advantage of technological advancementsin high temperature insulation, precision bearings, improved lubricantsand precision reduction gearing. The invention of commutating poles andimproved brush materials has permitted the design of do motors to nearlykeep pace with other technological advancements; however, at the presenttime commutation problems limit the output of do machines. The brushesand commutator bars can be an economic obstacle to development of a massproduced electric vehicle using do motors. Electronic commutation of domotors could be economical and could provide a breakthrough for higherspeed and higher power-to-weight ratio.
Because of its ease of control the conventional shunt motor withfield weakening is a popular choice for electric vehicles. It can becontrolled over a fairly wide speed range using a chopper-type fieldcurrent regulator to control the magnetic field. Weakening the fieldreduces the counter emf at a given speed to permit a greater armaturecurrent. The motor operates in essentially two regions as shown inFigure 6. At high speed (above the base speed), full voltage is appliedto the armature windings, and power is controlled by regulating the fieldcurrent. This is the field weakening region. At speeds below the basespeed, the motor is incapable of generating adequate counter emf to permitoperation with full voltage across the armature. In this region, armaturecurrent control is required. Armature current can be regulated by asemiconductor chopper switch which controls the on-off ratio. Figure 7shows a simplified chopper circuit for control of armature current.(ref. 2) Forfield current control, the power levels are lower and a transistorizedchopper would be used in the first analysis.
The torque/speed characteristics of the separately excited do motorare calculated in the computer program using the basic relationships forthe force on a conductor in a magnetic field and the voltage induced in aconductor moving through a magnetic field. Thus, the torque is directlyproportional to the product of the armature current and the air gap flux.The air gap flux is that required to produce a counter emf equal to theapplied voltage less the IR drop across the armature. This counter emf isdirectly proportional to the product of the motor speed and air gap flux.
A relationship is built into the program to calculate the air gap fluxas a function of the field current using a typical reluctance circuit fora do motor and a typical magnetic saturation curve for electrical grade iron.At motor speeds less than the base speed the field current is held at itsmaximum value which is set to give a magnetic flux high enough to slightlysaturate the iron between the coil slots. At speeds above the base speedthe field current is reduced and the flux falls along the curve calculatedfor the air gap, leakage flux and the magnetic properties of the iron.
20
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The motor speed is determined from the vehicle speed and drivelinegear ratios and tire size. Then the flux required for the counter emfis found as a first approximation ignoring the (IR) voltage drop acrossthe armature. Then the required armature current to produce the desiredmotor torque with the set value of air gap flux is found. Using thisarmature current, an IR voltage drop is calculated to find a new counteremf and air gap flux. An iteration procedure converges very rapidly tothe correct current and flux.
The identifiable losses used in the analysis are the following:
I 2 R loss for the fieldI 2R loss for the armatureWindage lossesBearing frictionEddy current lossesHysteresis losses
These losses are set initially at percentages of 'the total lossesat a design point and the appropriate values of resistances, dragcoefficients, other loss coefficients are calculated from this pointto permit subsequent calculation of losses at all other operating points.Using the specific rating of the motor at its design point, power andefficiencies over a wide range of operating points have been calculated.Figure 8 shows characteristics of a do motor calculated by theprogram listed in Appendix E. Motor efficiency and current are shown as
functions of motor output power with speed as a parameter. At speeds over2200 rpm, field weakening is used to control power output.
The usual alternative to the do traction motor is the three-phase acinduction motor. Using the squirrel cage construction, this is a ruggedmotor capable of mass production with relatively low cost, light weightand high efficiency. Operation of an ac motor from a do energy sourcesuch as a battery requires a do to ac inverter which can be an expensiveitem. Achieving regeneration with an induction motor can be difficultwith a do to ac conversion system as it must be a two-way converter
(i.e. a rectifier as well as an inverter) and it must maintain the accurrent to sustain the air gap magnetic flux.
In terms of the air gap magnetic flux the induction motor and separatelyexcited do motor are quite similar and thus the torque/speed characteristicsare much alike. At speeds below the base speed both motors operate withmaximum magnetic flux and above the base speed the flux is steadily reduced.In the case of the do motor above its base speed, the field current regulatorachieved the function. For the induction motor, the inductance of the magnetizingcircuit is such that varying the voltage to the motor in proportion to thefrequency when operating below the base speed achieves the desired maximumfluX. Keeping the voltage constant with respect to frequency when operatingabove the base speed achieves the steady reduction in flux.
Because the two motor types are magnetically quite similar, the torquecapacity and weights are potentially the same. The efficiencies are alsopotentially the same. The main differences are power factor, torque angle,controllability and operating ease as a generator.
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The torque/speed characteristics of the three-phase induction motor arecalculated in the computer program using the equivalent circuit (ref. 3) shownin Figure 9. The circuit is for one leg of a three phase motor. The valueE1 is the voltage across one leg and is equal to the line-to-line voltage fora delta connection or to _L times the line to line voltage for a wye connection.
VThe value R 1 is the resistance of the stator windings. The value R ? is therotor resistance referred to the stator and R 3 is an equivalent resistanceassociated with core losses. The values for the inductances and resistancesare calculated for hypothetical motor using the desired motor characteristicsat a design point. At this design point, the motor rated power, speed, slip,efficiency and power factor are used in conjunction with a hypotheticaldistribution of identifiable losses to permit the calculation of the circlediagram (ref. 3) of Figure 10 and all the circuit constants for the equivalentcircuit.
The value of the resistance Rl is set to give the I 2R losses of thestator at rated power. The value for R2 is set for the I2R losses of therotor and the value for R3 to give the total eddy current and hysteresislosses.
The inductances Xl and X2 are the leakage reactances and combined withthe magnetizing (transformer) reactance X3 to satisfy the specified powerfactor. An arbitrary power factor may be specified; however, excessivelyhigh power factor (say over 88 percent) will give leakage reactances whichare unrealistically low. With reasonable air gap dimension leakagereactances less than four percent of X3 will be unlikely.
A very low value of R2 will result in a motor with low slip and goodefficiency; however, very low values of R2 yield motor designs with excessivestarting current. For an industrial motor operated at a fixed frequency,good starting is very important. For an automotive motor operated from avariable frequency inverter, good starting torque is much less importantand the higher efficiency of a low slip motor is very desirable.f
The torque of an induction motor is dependent upon slip and voltage andcan be found from the values of the equivalent circuit elements as follows:
TK E 1 2 R 2
S[(R1 +_ 5?) 2 + (X 1 + X2)2
where K is a constant if saturation of the core is neglected.
A plot of torque as a function of slip is shown in Figure 11.
A special subroutine was written to calculate the characteristics ofthree-phase induction motors based on design parameters at rated power andspeed. The design parameters included slip at rated power, power factor,efficiency and the distribution of losses. The characteristics of a typicalmotor calculated by this subroutine is shown in Figure 12.
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6.4 Characteristics of Controllers
The most appropriate controller for a given motor type depends notonly upon the motor type but also upon the operating conditions for themotor. For an advanced propulsion system it seems obvious that regenerativebraking is necessary. When the motor is operated below its base speed,it will not be able to generate a counter emf greater than the batteryvoltage. Effective regeneration will require some means of voltageboosting unless the motor speed can be kept above its base speed eitherby using a motor with a low base speed or by continuously shifting gearsto.keep the motor speed high. The continual shifting of gears is awkwardand is an undesirable way to achieve regeneration. Reducing the basespeed of the motor may result in an unnecessarily large and heavy motor.
Voltage boosting can be accomplished with a do motor by use of asuitable chopper controlled voltage booster in the armature circuit.Figure 13 shows such a chopper controlled booster. Armature currentflowing when chopper switch Q2 is closed builds up a flux in the inductanceof the armature circuit. The decay of this flux when Q2 is turned offforces the current to flow to the battery through the diode D2. Theinductance of the circuit must be high enough to sustain the currentthrough D2 and to prevent excessive current through Q2. The amount ofinductance required depends upon the chopper frequency. The higher thefrequency the smaller the inductance. The chopper switch Q2 can be aSCR for a chopper frequency of 400 Hertzor less. Frequencies over 1 kHzwill require transistor switches.
For an .electronically commutated do motor, an electronic switchingcircuit is required. This circuit must switch the polarity of the armaturecoils in phase with the rotor and at a frequency dependent upon the rotorspeed times the number of poles. The number of armature circuits to beswitched can be selected to give smooth motor torque and low currentnipple. Three armature circuits would require a switching circuit similarto a three-phase inverter except that the turn-on and turn-off timesare tied to the rotor shaft position. Increasing the armature circuitsto more than three would increase the number of semiconductor switchesrequired while at the same time decreasing the current carried per switch..The choice of how many circuits would depend upon the current ratingsand costs of transistor switches
A simplified commutation circuit for an electronically commutatedmotor with seven armature circuits is shown in Figure 14. In this circuit,the switching elements are shown as SCRs. If high chopping frequenciesfor current control and voltage boosting are superimposed upon the switchingfor commutation, the SCRs would probably have to be replaced by transistors.
For a three-phase induction motor, a do to three-phase ac inverter isrequired. The output frequency must vary as the motor speeds up or slowsdown in order to maintain a desired amount of slip. The power factorof the load can vary substantially so the inverter must be capable ofdriving a highly inductive load.
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Above the base speed of the motor, the inverter output voltageis limited by battery voltage. At speeds less than the base speed, thevoltage should increase linearly with frequency to insure maximum air gapflux. A chopper switch for the armature current used with a voltagefcadback loop can provide voltage control.
Voltage boost for regeneration can be achieved with difficulty in asimilar way to that used with a do motor providing that the currentrequired for air gap flux can be maintained. and the frequency for adesired negative slip can also be maintained.
The control circuits for the electronically commutated do motor and thethree-phase induction motor shown in Figure 15 are very similarin terms of the number and types of semiconductor elements used.. Themain difference is the manner of maintaining rotor current and its effecton air gap flux and motor control. For the electronically commutated domotor, rotor current is directly controlled to assure air gap flux. Aseparate field excitation control unit is used to maintain and control therotor current. Slip rings may be used or a brushless inductor design maybe used. For the induction motor the rotor current is produced bytransformer action due to the ac current in the stator inducing an acvoltage in the rotor. The induced rotor voltage goes to zero for zeroslip or for zero current in the stator. The condition of zero voltageat zero current for the induction motor is similar to the conditionencountered in a series wound do motor. For the series motor to maintainstability as a generator, it is common to use a diverting chopper circuitto control the field current independent of the current returned to thebattery. A similar mode of separating the current for field magnetizationfrom that returned to the battery is required when operating the inductionmotor as a generator. One way of viewing the control of the inductionmotor is to consider the out-of-phase current component as the magnetizing(or field current) and the in-phase component as the power producingcurrent. Then essentially the controller by use of slip control and currentcontrol endeavors to control both the in-phase and out-of-phase current.The total current in the semiconductor elements for a given power is thussomewhat higher for an induction motor than for an electronically commutatedmotor as it must handle both the in-phase and the out-of-phase current.
The computer modeling for the controller characterizes the lossesin terms of three parameters. There is a fixed loss. A loss associatedwith a fixed voltage drop across the semiconductors and there is a lossproportional to the square of the current. The loss factors for theseparameters are adjusted for the type of controller to be consistent withthe rating of the semiconductor elements and normalized in terms of inputcurrent.
6.5 Characteristics of CVTs
The use of a CVT to extract energy from a flywheel in a smooth controlledmanner requires a smooth and continuous variation in the speed ratio ofthe CVT. A variety of CVT types can provide such continuous changes inspeed ratio, but additional constraints on the CVT for use in an advanced
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propulsion system arelight weight and high efficiency. (refs. 4,5) Hydraulictype CVTs appear to have poor efficiencies at light load although theycan have very acceptable efficiencies at high loads. Conventionalbelt type units appear to have inadequate power capacity, poor life and excessivelosses (ref. 6). New (refs. 7,8,9) traction type devices seem to hold promise;however, much development work will be required to perfect a unit foruse with a high speed flywheel. If the unit were developed for the highspeed and low torque at the flywheel shaft-it could be fairly small.
For the preliminary analysis it was assumed that a light-weighthigh-speed traction-type device could be developed. If such a unit weredeveloped it would have to have good efficiency in order to also have gooddurability. Traction devices with poor efficiency have excessivewear. Good efficiency and good life go hand-in-hand.
It was assumed that the losses for a traction type CVT could beexpressed in terms of slippage, windage drag and spin torque. The slippageresults in a loss of speed so that the output speed is slightly less thanthe theoretical or ideal output speed. The difference in speed is expressedas a percent creep and is believed to be a function of transmitted torqueas shown in Figure 16.
The actual torque transmitted will be less than the ideal torquebecause of losses due to the nature of the traction geometry. The idealgeometry for the traction contact will be pure rolling (ignoring the slipmentioned above); however, the actual contact zone in a traction deviceis an area that is enlarged by elastic deformation of the material incontact. Within this zone there may be a variation from pure rollingwhich may be termed spinning, and thus the loss is called spin torque.An example of high spin torque is a front tire with excessive toe-in.A good design is one which minimizes spin torque. Figure 17 shows therelationship of torque loss due to spin torque.
The windage drag used in the analysis is essentially a viscous dragtorque. This torque loss is a linear function of speed.
The values of spin torque, creep and viscous drag were chosen to givea CVT efficiency similar to values measured by others. (ref. 10)
6.6 Characteristics of Flywheels
The flywheel for use in an energy storage unit should be lightweight, have low losses, low volume and minimum adverse effects upon vehicleperformance. Recent development in high-specific energy f1vi-iheels (ref. 11)using high-strength fiber-composite material indicate that such materialshave good promise, and moreover indicate that suitable flywheels can bedeveloped in the desired time frame. (ref. 12)
For a given amount of available energy a high-specific strengthfiber-composite flywheel will be lighter weight and less expensive thanhigh-strength steel flywheels. (refs. 13,14)
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The specific energy is proportional to the strength-to-weight ratioof the material. Thus, high-strength and low-weight materials can yieldhigh-specific strength. The relationship for kinetic energy-to-weightratio is as follows:
KE _ aWT - K 'p
where KE = Kinetic EnergyWT = WeightK = Constant; depends upon shapea = Stressp = Density
Less obvious but very important is the fact that the fiber-compositeflywheel has much less angular momentum and is thus safer and has lessgyroscopic moment than a steel flywheel.*
The stored energy in a flywheel is given as follows:
KE = 1Iw2
where I = Moment of inertiaw = Angular velocity
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M = Iw
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The total amount of energy required for the flywheel depends uponthe driving conditions to be satisfied. If the vehicle is to be drivenover the SAE J227a Schedule D exclusively and always over a level course,a minimum amount of energy could be approximated by examining the maximumkinetic energy of the vehicle. However, any practical vehicle must be ableto drive a multitude of courses and operate on upgrades and downgrades.
A way of analyzing the energy storage requirement is to consider thevehicle operating at a point where it has a set value of flywheel energywhich permits the vehicle to either accelerate or decelerate. The vehicleshould be able to either go up a grade with some acceleration capabilityor to go down a grade with some regenerative braking capacity. Figure 18shows an example of a set point for the flywheel and shows the energy capacity
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r*The angular momentum and gyroscopic moment of a fiber composite-flywheelis about 25% of that for a steel flywheel of the same energy.
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for braking and for acceleration. The total available energy is approximatelysix times the minimum energy required for the SAE J227a Schedule D.
For the preliminary analysis, a uniform rate energy loss due toaerodynamic drag and bearing friction was assumed.
6.7 Characteristics of the Drivetrain Components
The drivetrain components of concern are the final drive gears (axle)and the multi-speed transmission. It was assumed that each of these unitscould be characterized by their gear ratios and by certain types of energyloss coefficients. Three types of energy losses were used for each unit.These losses were expressed as torque losses which were then calculatedas energy losses by multiplying by rotational speed. The three torquelosses were as follows:
a. Constant torque (example: bearing preload)b. Loss proportional to applied torque (example: dear friction)c. Loss proportional to speed (viscous drag)
The values of the coefficients for these losses were adjusted to givea reasonable loss at rated power. (ref. 6)
6.8 Performance Comparisons
The candidate propulsion systems are all compared on the basis of thesame base weight and payload. Aerodynamic drag and tire rolling resistancecoefficients are the same for each vehicle. The basic loss coefficientsfor the motors and controllers are also the same for the same type ofdevice. The differences in configurations and motor types do lead todifference in the propulsion system weight and effective efficiencies.Differences in gear ratios are also required. The costs of differentcandidates will increase as weight and complications increase. Thelikelihood of successful development is different for the various candidates.
Table 5 lists some of the basic characteristics of the candidatepropulsion systems. Candidates Al through A8 have a single drive axleand a single traction motor. Candidates B1 through B8 have single driveaxle and two traction motors. Candidates Cl through C8 have two driveaxles and two traction motors. Candidates D1 through D4 have a singledrive axle and a single traction motor.
Two types of flywheel drive motors are represented. The PM typeshave permanent magnets for field flux and the WF types have separatelyexcited wound fields. The WF types use field control and the field can beshut off to reduce standby losses associated with eddy currents and hysteresis.Two traction motor types are represented in the candidates. The ACl andAC2 types are three-phase induction motors specially designed for use inelectric vehicles. The DC1 and DC2 types are separately-excited electronically-commutated do motors specially designed for electric vehicles. The domotors have a lower base speed than the ac motors so the axle gear ratiosare different as shown in Table 5.
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41
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The traction motors and motor controller characteristics are summarizedin Table 6. All motors and controllers were rated for a 240 volt do system.The rated power is in watts. The specific weight is normalized to a basespeed of 3600 rpm,
All motors were initially selected to give a total rated power of40 kW. The main difference in the motors for the various candidates arethe base speeds and resultant torque. The slower speed motors would havehigher torque and greater weight. The motors for candidates withouttransmissions require greater torque to achieve acceptable performance.
The flywheel generator controller, battery, flywheel, and CVTcharacteristics and transmission factors are summarized in Tables 7 and 8.The three main characteristics for the preliminary analysis of the CVTfor Dl through D4 are the loss factors. The spin torque is taken as fourpercent of rated torque and the creep is set at three percent at maximumtorque. The viscous drag is set at two percent of rated torque at maximumspeed. With these values the efficiency at rated torque and speed isabout 91 percent.
The calculated performance of the candidates is summarized in Table 9.The test weight of the various candidates ranges from a low of 4097 poundsfor D4 to a high of 4559 for C4. All candidates have adequate power tosatisfy all the driving requirements. All would meet the range requirementof 100 miles if some small adjustment were made in battery weights. Therange in the repeated SAE J227a Schedule D using 1600 pounds of batteriesvaried from a low of 91.8 miles to a high of 120.3 miles. Part of thedifference in range is due to differences in energy consumed per mileand part is due to greater available energy from the battery as a consequenceof load leveling the battery to permit greater energy extraction. Theenergy per mile* varied from a low of .55 MJ/km (248 Wh/mile) to a highof .68 MJ/km (304 Wh/mile). The range for a steady 72 km/h (45 mph) cruisevaries from a low gf 191 km (118.7 miles) to a high of 250.5 km (155.7 miles).Changing gear ratios and shift points can improve the range at 72 km/h (45 mph)but may have an adverse effect upon the performance and upon the range ina variable speed driving cycle.
6.9 Other Factors
This section is prepared to comply with clauses (2) and (3) of thecontract requirements which read as follows:
"The contractor's recommendation shall include supportinginformation that provides: (1) a summary of the physical andoperating characteristics of the candidate systems (2) anappraisal of the advantages of one versus the other and (3) asummary of component and system technology advancements required."
*This is energy from the battery. To obtain wall plug energy, thereoharger efficiency and battery efficiency must be considered.
42
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Clause (2) above is understood to be a qualitative comparison of the28 alternates studied under Clause (1). In order to make a consistentcomparison,values of "goodness" were assigned to the "qualitities"considered significant. These goodness values were multiplied by aweighing factor assigned according to the importance placed on the particularquality to the overall goodness of the power system. Then for eachalternate the products were added together to give a number that indicatedthe overall desirability of the alternate. Finally the desirabilitieswere divided into low, medium and high and presented in Table 10.
The comparison was based on subjective appraisals of goodness andimportance. The numbers were not used as the basis of comparison but onlyto keep track of the comparison process. For example, if the alternateshad the same or nearly the same desirability the reasons why they came outthat way were reexamined and the numbers changed if necessary to agree withthe overall appraisal.
The summary of the technology advances required for the variousalternates requested by Clause (3) of the contract is provided by thefollowing discussion. These advances are discussed under the headings ofthe components or parts of the system to which they apply. The comparisonof the alternates with respect to the extent of such advances required issummarized in Table 11.
With the possible exception of the CVT, none of the alternates requirebreakthroughs on the scale typified by high temperature storage batteriesfor example. The type of advances required are reduction in size, weight,cost, and increase in durability.
Generators and Motors
The properties of the electrical machines depend basically on physicallaws and the properties of iron, copper, and magnetic and insulatingmaterials. The improvements in these machines that can be expected are intheir design for higher speeds and higher short time overload capacities.Higher speeds will reduce weight but increase eddy current and hysteresislosses. Reduction of losses can be accomplished by the use of higher gradeiron, thinner laminations, and finer subdivision of the conductors. (Refs. 15,16)All of these approaches are understood. The extent of their applicationis set by manufacturing cost which can be greatley reduced by productionengineering effort.
Improved insulating materials together with design for forced coolingby either air or liquid coolants can greatly increase overload capacity asrequired to obtain the short-time performance expected of passenger cars.
47
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Controls
Electrical and many non-electrical systems today take advantage of thebreakthrough in control technology of the microcomputer. The microcomputeris well suited to process and generate the various signals needed for thecontrol of an electric vehicle. There also may be simpler approaches tothe problem like specialized LSI chips. In any case, the only advancesrequired are those already available for application to the electric car.
Step Transmissions
No basic advances appear to be necessary to multi- t--. io transmissions.These devices have been perfected for internal combustion-engined cars tothe point where they are as small and light as necessary for electricautomobile applications.
Reduction of losses through better bearings, reduction or eliminationof oil churning loss, reduction of control power and clutch or brake dragshould take place through redesign of the present relative lossytransmissions and drive systems for electric vehicle application.
Continuously Variable Transmissions
These devices have never been successfully applied to automobileson any significant scale. They may very well require an advance intraction coefficient or contact fatigue strength beyond the valuescurrently being obtained. Transmissions designed following ball bearingpractice are large, heavy, and expensive. Whether or not they are toolarge, heavy, and expensive is not definite but it is possible that theircharacteristics put them outside the range of practicality for vehicleapplication unless a significant technological advance can be made.
Power Converters
Most of the alternates employ semiconductor power converters betweendo and ac devices. The technology of these converters is so new thatsignificant improvements would not be surprising. The power handlingdevices, thyristors, or transistors now available have the capabilityrequired although increase in the frequency capability of thyristors andthe current capability of transistors is very desirable. The advanceswhich are necessary and can be expected are in simplifying and packagingtheir auxiliary equipment, such as the firing and protective circuitry,and in reducing the filtering required. One advance, the development ofhigh-power transistors, appears to have already occurred. Of course, pricesmust be reduced drastically but this can be expected to result from productionfor a large competitive market.
Other Problems
The foregoing discussion considered the elements which differed betweenthe alternates and is summarized in Table 11. In addition there are advancesnecessary or desirable in the elements used in all alternates.
50
The flywheel is probably the most important component from thestandpoint of development required. Vehicle flywheels (ref. 5), while extremelypromising, are in an early state of development. Only a few vehicles arein operation today with flywheels in their power systems and in many ofthese the flywheel energy-to-weight ratio is too low for passenger roadvehicles. Laboratory demonstrations (refs. 14,17), however, have shown energy-to-weight ratios considerably better than lead-acid batteries. The applicationof these wheels as power boosters for road vehicles has only barely begun. (ref. 11)
Specifically, durability and accident hazard must be determined fora flywheel design having the characteristics postulated for the powersystems studied.
Advances are necessary and will certainly occur in the "packaging" andinterconnection of automotive electrical equipment. The present style isset by industrial lift trucks and similar equipment where weight is lessimportant and space restraints less demanding than in a passenger car.Even in the latest electric vehicles, electric equipment connecting partsand equipment layout is more typical of industrial than of passengervehicle practice.
6.10 Recommended Candidates for Task II
The candidates recommended for further examination in the design trade-off studies were candidates D4, D2, A6, A8 and B5. The two candidates,D4 and D2, represented the best two candidates in terms of range, but havesome obvious developmental problems in that no suitable CVT is currentlyavailable.
Candidates A6 and A8 are the most attractive of the non-CVT candidates.Their ranges are just slightly less than those for the best multi-motoredcandidates, but their relative simplicity and lighter weight will probablymake them more cost effective than any of the multi-motored candidates.The most attractive of the multi-motored candidates is B5 and it is keptfor further examination to determine if the expected difference in costeffectiveness is born out when the candidates are optimized.
Recommended Candidates for Task II Studies
A6 AC Induction Motor With flywheel/Generator
A8 DC Brushless Motor With Flywheel/Generator
B5 Two AC Motors Without Transmission, With Flywheel/Generator
D2 DC Brushless Motor with Flywheel/CVT
D4 AC Induction Motor With Flywheel/CUT
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7. DESIGN TRADE-OFF STUDIES
The characteristics and design of the five recommended candidateswere examined in more detail during the design trade-off studies. Inthe preliminary analysis, all candidates had the same total weight ofbatteries and same total installed power. However, during the trade-offstudies, the design and performance factors for each candidate areexamined to achieve a more optimum design and various differences inweight and power requirement emerge. As the details of the design becomemore specific, the estimates of life-cycle cost become more meaningful.
The candidates A6, A8, D2, D4 and B5 are shown in more detail inFigures 19, 20, 21, 22, and 23.
7.1 Design Parameters Studied
Factors affecting driveline efficiency were examined to find waysto reduce losses and to determine the improvement in range which couldresult from these improvements.
Refinements in the estimates of motor weights were made by examiningthe motor designs in more detail. Calculations were made for magneticflux in the air gap to confirm that the required overload torque could beachieved. Some modification of the computer subroutines were made toreflect the overload capacity of induction motors at breakaway torque.Variation in various design parameters for the induction motor was examinedto determine the potential gain in range which can be achieved by improvingthe power factor of the motor or.by reducing the slip.
Variations in gear ratios and shift points were examined to determineif the optimum operating points had been selected.
Different schemes for energy management via the use of the flywheelwere also examined. Battery leveling and peak power shaving was alsoconsidered.
The battery weights were adjusted to give very nearly the same rangefor each candidate.
The losses in the transmission and final drive axle are each characterizedby three coefficients (Table 12). The first coefficient used in theanalysis represents the no-load drag torque at low speed. The value of thetorque is affected by the bearing design and bearing preload. Taperroller bearings with high preload will give higher no-load torque than ballbearings or spherical bearings of modest preload. By careful design thisfriction can be lowered
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The second coefficient is for the viscous drag torque. The amount oftorque associated with this coefficient is proportional to speed. Thevalue of the coefficient is dependent upon the geometry of the transmissionor axle and upon the viscosity of the lubricant. This too can be reducedby good design and careful selection of the lubricant.
The third coefficient is for the gear and bearing friction associatedwith the torque loading. The value of the frictional torque is dependentin part on the geometry of the gear train and the unit loading on the bearings.The value of torque is also dependent upon the properties of the lubricant.
Reductions of these coefficients were arbitrarily made to determine thepotential improvement. The values examined are shown in Table 12. Theeffects on driveline efficiency and power loss are shown in Table 13. Theimprovements in range are shown in Figure 24.
The power required for the different driving conditions vary somewhatfor the different candidates because of slight differences in theirweights and efficiencies. Table 14 summarizes the peak power requiredfor various driving conditions for the five candidates. The greatestpower requirements are for the acceleration from zero to 55 mph in fifteenseconds and for braking in the deceleration portion of the SAE J227aSchedule D cycle. For both of these periods, the duration of the powerpulse is short enough that the short-term overload capacity of the motorcould provide the power, even though the continuous power rating is muchlower. The power available for the acceleration on the six percent rampcan be higher than the continuous power rating of the motor because theduration of this six percent ramp acceleration is less than 30 seconds.The power required for the steady 89 km/h (55 mph) on a four percent gradeis used to set the continuous power rating for the motor. Using thispower as the continuous power rating, the overload factor for the s'ixpercent ramp acceleration is about 40 percent for the three non-CVTcandidates and the overload factor for the zero to 89 km/h (55 mph)acceleration is about 100 percent.
The required short-term overload capacity of 100 percent is normalfor electric motors. Air gap flux calculations and peak current allowancesshow that the motor designs considered for these propulsion systems haveabout 150 percent short-term overload capacity. The subroutine forrepresenting the ac motors were modified to assure that the maximum torqueexceeds 200 percent of rated torque.
Variations in design parameters for the induction motor will givedifferent amounts of overload capacity. A range of different values ofrated slip and power factors were examined for motors having the samerated power, speed and efficiency. The characteristics of these differentdesigns are shown in Table 15. For constant efficiency at the design point,a low slip motor has low rotor resistance (R2) and higher stator resistance (Rl).Permitting the slip to rise by use of higher rotor resistance, requiresthat the stator resistance be lowered to keep the efficiency up. Thestarting torque increases as the rotor resistance increases and permitshigher slip at the breakaway torque, however, the maximum power does notincrease. The drop in speed due to increased slip is not offset by increase
59
s
rr
Table 12. Loss Coefficients Used in Driveline
FOR POINT # I II III
AXLE:
AO .6779 .4519 .2260
A l .135 x 10-3
.09 x 10-3 .045 x 10-3
A2 .02712 .01808 .00904
TRANSMISSION:
TO .2260 .1507 .0753
Ti .451 x 10-5 .3 x 10 -5 .15 x 10-5
T2 .09039 .0602 .0301
IV
.1692
.3383 x 10-4
.89 x 10-2
.05637
.1128 x 10-5
.0301
A0 - TO = NO LOAD TORQUE AT LOW SPEED Nm
Al - T1 = VISCOUS TORQUE COEFFICIENT Nm/rpm
A2 - T2 = GEAR & BEARING FRICTION Non-dimensional
60
4 1
61
Table 13. Transax1e Losses
ROAD POWER
Watts
POWER MOTOR
Watts
o
Watts
DRIVE LINE
EFFICIENCY
(Percent)
ORIGINAL AXLEI
TRANSMISSION LOSS FACTORS POINT I
! 6136 7869 1733 77.9
t 21475 24929 3454 86.1
55251 61194 5943 90.3
LOSS FACTORS REDUCED BY 1/3 FROM POINT I
6136 7273 1137 84.4
21475 23752 2277 90.4
55251 59179 3928 r 93.4
LOSS FACTORS
r
REDUCED BY 2/3 FROM POINT I
6136 6697 561r1
91.6
21475 22603 1128 s
f
95
55251 57199 1948 96.6
POINT IV LOSS FACTORS FOR CONCEPT A6, D4.
j
HIGHER SPEED AC MOTOR SYSTEMS ONLY
6136 6614 478 92.8
21475 22520 j 1045 ! 95.4
55251 ! 57112 'j t
1861 96.7
61
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in torque as shown in this table. This loss in power is somewhat deceptiveas the power values are for a constant frequency input to the motor whichallows the motor to slow down as the slip increases as it would for anormally operated ac motor. However, for the electric vehicle the frequencyis increased as slip increases so that the motor does not actually slowdown. The main value of the table is the display of resistances andreactances associated with different values of slip and power factor. Thetable shows clearly that the ratio of leakage to magnetizing reactancemust be low to achieve a high power factor and shows that very low rotorresistance is required to achieve a low value of slip.
The different values of slip and power factor were examined for motorsof the same efficiency at the design point power and speed; however, theywill have different efficiency at powers and speeds other than that atthe design point. Consequently, the range and energy consumption per milecan be different as shown in Table 16 for Schedule D cycle. The motowith lower slip does not give better range because the reduW on in I Rlosses in the rotor is more than offset by an increase in I R losses of thestator. Increasing the power factor increases the range and decreasesthe energy consumption. Unfortunately it will be very difficult to achievea power factor much higher than 88 percent.
Table 16. SAE J227a Schedule Cycle Range Obtained for MotorsListed in Table 15
Power EnergySlID
T.Factor.—
kmRan a
14 1es)Consumption
Wh/mi MJ/km
1 84 168.98 (105.00) 222.68 .4982 84 170.04 (105.66) 221.60 .4953 84 171.05 (106.29) 220.59 .4934 84 172.01 (106.88) 219.65 .4914 80 169.25 (105.17) 222.50 .4984 88 174.66 (108.53) 216.94 .485
Increasing the battery weight increases the vehicle range by increasingthe on-board energy storage, but does so at the expense of greater vehicleweight. The vehicle weight increases by more than the increase in batteryweight because the vehicle structural weight must be increased to carry theadditional battery weight. This increase in vehicle weight causes anincrease in energy consumption. The additional battery and structural weightwill also cause an increase in initial cost of the propulsion system. Theeffects of battery weight on vehicle weight and range is shown in Table 17.The desired range is 161 km (100 miles) so the battery weight should beadjusted to give this range. Figure 25 shows the range as a function oflead-acid battery weight and Table 18 summarizes the vehicle weights andenergy consumption with the battery weights adjusted to give a range of161 km (100 miles).
65
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7.2 Control Modes
The controls for power flow are summarized in Table 19. The acmotor frequency is controlled in a manner to give a desired amount of slip.The controller thus needs a motor speed signal so that motor-rotationalfrequency can be compared to the controller output frequency. The voltageis increased linearly with frequency until the maximum voltage allowedby the battery occurs. The maximum voltage should be reached as the motorreaches its base speed.
In addition to controlling motor power and flywheel power, the motorspeed is set within prescribed limits by shifting the gears in the multi-speed transmission. A range of gear ratios were examined as were a rangeof shift points to assure that the shift points selected match themotor efficiency curve. The differences in range resulting from differencesin gear ratios are shown in Table 20. The variation in range is trivialindicating that the selected ratio is very close to an optimum value.The change in shift procedure shown in Table 21 produced a range improvementby making the up-shift point to top gear dependent upon torque requirement.For a full power acceleration, the up-shift point is delayed. This changepermits the zero to 55 mph full-power acceleration to stay in second gearwhile allowing the 45 mph cruise portion of the Schedule D to be in topgear. An extra four to five percent range appears possible by suchup-shifts.
7.3 Energy Management
The use of a high-power flywheel energy storage device can provide asubstantial increase in range and performance for an electric vehicle if the energyto and from the flywheel is properly managed. Good management (ref. 18) ofavailable energy can have a beneficial effect on battery life and can increase theamount of energy that can be extracted from the battery. There are severalreasons why more energy can be extracted. One reason is that the totalenergy output capa6ity of the battery is greater if the battery power islow. Batteries can be designed for higher power or for greater energybut not always for both high power and high energy simultaneously. Theuse of a flywheel in a way that reduces the battery power level increases
the extractable energy. (ref. 19) The battery power level can be reduced byleveling the battery current drain or by eliminating some of its peak powerperiods.
Another reason why more energy can be extracted is that a criteriafor judging the discharge of a battery is the inability of the vehicleto meet minimum acceleration requirements. The flywheel car provide theextra boost of power for acceleration even though the bc,ttery is nearlydischarged and not capable by itself to provide the needed power. Thisextra boost in power can compensate in part for battery degradation withaging or adverse temperature conditions.
The effective use of the flywheel is obtained when it is used to reduce
peak current drain from the battery and to provide additional power foracceleration. Channeling all of the battery energy through the flywheel would
69
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70
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Table 20. Range vs. Various Transmission Ratiosfor SAE J227a Schedule D
Concept A6
Transmission RatiosHigh Sec. Low Gear Range
(Miles)
1 1.58 4.04 96.369
1 1.64 3.96 96.877
1 1.70 3.90 96.969
1 1.74 3.86 97.080
1 1.80 3.80 97.170
1 1.86 3.74 97.083
71
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not be an efficient way to utilize it unless it has very highin-and-out efficiency. The flywheel can add a parasitic load to the propulsionsystem in terms of its energy losses as well as adding an extra weightburden to the vehicle. Through proper utilization and sizing the advantagesof power boosting and effective battery current reduction, the flywheeladd benefits which more than offset its parasitic load. To be effectivethe it must be sized and used to minimize its energy losses and tomaximize its use in recovery of braking energy, in reduction of effectivebattery power and in boosting vehicle performance.
Clearly, the vehicle usage has an impact upon the ability ofthe flywheel to be effectively used. A vehicle used mostly at steadycruise conditions has little opportunity to use the flywheel for accelerationor braking, However, a vehicle used in service involving a great deal ofstop and go driving would use the buffer most often.*
To minimize the energy loss associated with the in-and-outefficiency of the flywheel the exchange of energy should be made under themost favorable conditions, i.e., those conditions where the best efficiencyoccurs if a choice is possible. Clearly, the need to meet accelerationand braking needs presents little choice. For both acceleration anddeceleration a division of power from the battery and flywheel is possible.For recharging the flywheel from the battery, some choice of rate of rechargeand timing of the recharge is possible.
Several schemes have been examined for the distribution of power foracceleration and deceleration. One scheme is to use the flywheel to supplypower in proportion to the acceleration rate and absorb power in proportionto the deceleration rate. Another is to prejudge the power level oversome driving cycle and set the battery power to satisfy the average needsand force the flywheel to deliver the time dependent deficiency or acceptthe excess. This is easy to accomplish in theory but is hard to do inpractice. Still,another scheme is to set positive and negative limits onthe battery current and have the flywheel provide the current in excess ofthe positive limit or accept negative current beyond the negative limit.A variety of flywheel recharge schemes are possible, but a recharge at therate for the greatest efficiency is desired. A measure of the flywheelstate of discharge is required for use by the recharge controller.
Figures 26, 27, and 28 illustrate the power and current in theSchedule D driving cycle for these three energy distribution schemes forcandidate A8. Tables 22 and 23 show the range and energy consumption forcandidates A8, D2, A6 and D4.
For the SAC J227a driving mode, setting battery current limits givesthe greatest range and least energy consumption. For different drivingmodes, like acceleration from zero to 55 mph or the Federal Urban Driving
*For example, the range improvement via use of a flywheel would be greaterfor the SAE J227A Schedule C'than for the Schedule D because there aremore stops and starts per mile for the Schedule C.
73#I
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Cycle (FUDC), varying the flywheel generator and battery current accordingto acceleration, gave the best overall results and this scheme was usedin all further work of this study.
7.4 Performance Comparisons
After the candidate systems were optimized for best gear ratios, shiftpoints, motor overload capabilities and energy management schemes, thebattery weights were adjusted to give a uniform range in the Schedule D.cycle. All of the candidates meet the driving performance requirements.The weights and energy consumptions are summarized in Table 24. The twomotor concept B5 has the greatest battery weight as well as the greatesttotal weight and energy consumption.
The CVT candidates require less battery weight and use less energyin the D cycle than do the A6 and A8 candidates. However, the CVTcandidates have lower range for steady 45 mph driving.
The energy consumption per mile shown in the table is the batteryenergy rather than wall plug energy. Dividing by the battery and chargerefficiencies brings the wall plug energy consumption to a value in excessof the goal of 559 kJ/km (250 Wh/mile).
For a charger efficiency of 85 percent and the given lead-acid batteryefficiency of 60 percent, the wall plug energy consumption of the bestcandidate D4 increases from .466 MJ/km (208.3 Wh/mi) to .91 4 MJ/km (408 Wh/mi).
7.5 Cost Comparison
The life cycle cost for the five candidates are summarized in Table 25.(Cost was generated following cost estimating guidelines listed in Appendix D.)The B5 candidate is the least attractive although all five candidates meetthe goal of a life cycle cost less than $.05/km ($.08/mile). The otherfour candidates are very close in cost. The energy costs of the CVTcandidates are less than those for A6 and A8, however, the highermaintenance cost more than offset the energy savings. Lower acquisitioncosts are projected for the CVT candidates which compensate for theslightly higher operating cost compared to A6 and A8.
7.6 Candidates Recommended for Conceptual Design
All candidates in Table 24 appear to be capable of meeting range,performance and cost objectives. The candidates using CVT concepts D2and D4 did not meet the constant 72.4 km/h (45 mph) range requirement of209 km (130 miles) but this can be solved by adding approximately 20 kg(45 lbs) of lead-acid batteries. However, none appear to meet the wallplug energy consumption goal of 250 Wh/mile unless very efficient batteriesand recharge units are used. All have some developmental risk which mustbe more fully studied.
79
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Candidates A6 A8 B5 D2 D4AC DC AC DC AC
Acquisition Cost 3460 3491 4207 3307 3287
Annualized AcquisitionCost 346 349.1 420.7 339.7 328.7
Discounted Annual Cost@ 2% Discount Rate
Electricity 129.3 132.9 149.1 127.1 125.7
Repair & Maintenance 100.3 100.3 86.2 116.1 116.1
Battery Replacement 99.8 101.8 115.2 94.6 93.3
Power Train Salvage -3.8 -3.8 -4.7 -3.6 -3.6
Battery Salvage -25.3 -25.8 -29.2 -24.1 -23.7
Discounted Annual OperatingCost 300.3 305.4 316.6 310.1 307.8
Present Value ofCycle Cost/year 646.3 654.5 737.3 640.8 636.5
Present Value of LifeCycle Cost/mi ' .065 .065 .074 .064 .064
All figures are in 1976 dollars.
81
6 1
61
In selecting candidates for conceptual designs, it seems appropriatethat systems with minimized development risks should be preferred. Sincethe performance differences and life cycle cost difference among A6, A8,D2 and D4 are not great, other factors such as the balancing of developmentalrisks and the keeping of options open lead to the recommendedcandidates, A6 and D2.
The flywheel/generator of A6 provides a special source and sink forthe reactive kVA of the three-phase ac induction motor and may simplifythe development of the do to ac inverter controller capable of regenerationover a wide-speed range.
The D2 candidate with its do motor and its stable field excitationremoves an element of developmental risk which partly offsets the higherrisk associate with the development of a suitable CVT.
Recommended Candidates for Task III Studies
A6 AC Induction Motor With Flywheel/Generator Unit
D2 Electronically Commutated DC Motor With Flywheel/CVTUnit
826I
8. CONCEPTUAL DESIGN
In the design trade-off studies two advanced propulsion candidateswere selected for conceptual design. Layout drawings of components wereprepared. Design details for the inverter and control circuit wereexamined to confirm the ratings of semiconductor components. Sizes andtypes of CVTs were examined for their suitability.
Safety factors and component layout constraints force several modi-fications of the configurations and sizes of components emerging from thedesign trade-off studies. Most significant of these changes are the selec-tion of a battery voltage of 96 volts, the use of transistorized choppersand inverters, and the reduction in the size and energy storage of the fly-wheel from 6.84 MJ (1900 Wh) to 2.44 MJ (678 Wh.)
Appendix I and II list the specifications of the two conceptual designs.
8.1 System Voltage and Semiconductor Types
During the preliminary analysis and design trade-off studies a sys-tem voltage of 240 volts do was considered with SCRs being used forswitching in the inverters and choppers. This voltage is higher thancommonly used in electric vehicles, but seemed reasonable for an advancedconcept which would require a high battery weight to achieve the desiredrange of 161 km. The higher voltage would allow a lower current for agiven power, and this lower current would give lower losses in the semi-conductor switches. The lower current would also allow smaller wiringfor motor connections. Switching with SCRs is compatible with thehigher voltage and was believed to be more efficient and less expensivethan switching with transistors. (refs. 20,21) However, as the designsevolved the practical limitations of SCRs became apparent. (ref. 22).
The postulated advantages of high voltage had to be compared withthe known disadvantages. Numerous battery manufacturers were contactedregarding the practicality of higher voltages, and all were discour-aging (ref. 23).
An increase in battery voltage would require an increase in the numberof cells. As presently manufactured the cell sizes would not be decreasedenough to provide an efficient utilization of space and weight. A 50-amphour cell uses the same mechanical accommodation as a 75-amp hour cell. Alarge number of small cells would require more maintenance than a smallnumber of large cells. (ref. 24) The reliability of the small cells may alsobe less than that for the large cells. It is believed that the attemppt toincrease lift truck voltages from 36 volts to 72 volts was unacceptablebecause there was a higher cost for servicing the additional cells.
83
Higher voltages increase the danger of fire and electrocution.There is a danger of leakage current on the outside of the cells andacross the trays. Good housekeeping and cleanliness can reduce the dangerbut at an increase in maintenance cost. It is common practice in carsystems to group the cells in separate trays and to avoid having more than24 volts between adjacent batteries. In spite of these practices suddenfires are still a problem.
High voltage do is much more hazardous than high voltage ac.(refs. 25,26)A do voltage will sustain an arc at a level where an ac voltage will not. Thedanger of electrocution from do is much greater than from ac because aperson cannot let loose from the do source. Of course, protection from the
hazards are possible as high voltage do is used for light rail and trolleybus transportation systems. However, the special means for protection willadd to the cost and may not always be effective. (ref. 27) The use of lowervoltage will not completel y solve the safety problems, but will make thesolutions easier and less expensive.
The potential gain due to use of higher voltage is an improvement incontroller efficiency and a reduction in controller cost by lowering thecurrent rating of the semiconductor switches. However, analysis of anominal 100 volt do system shows that reasonably high efficiency at anacceptable cost is obtainable.
Trading off potential safety hazards, maintenance cost and efficiencygains, it appeared that a nominal 100 volt do system should be designed.Considering six-volt batteries at 75 pounds each, a system with 1200pounds of batteries has 16 such batteries and a total of 96 volts. Theconceptual designs were based on 96 Vdc.
Examination of inverter and chopper circuits and frequency requirementsfor the high speed motors, made it apparent that device shut-off timeswould be a very serious problem with SCRs Pulse width modulation andhigh frequency chopping would simply not be possible with SCRs
Of course, low frequency systems compatible with SCRs could be con-sidered but the size and weights of components for a low frequency systemare unattractive. A chopping or modulating frequency of about four kHzappear to be desirable. Much lower fre quencies would require large reactorsto keep the ripple current low. (ref. 28) Much higher frequencies would requirespecial magnetic materials to minimize eddy current losses. The limita-1 • ions of power diode turn-off times will prevent use of very high frequencies.
Transistorized choppers and inverters are used for the conceptualsign rather than SCRs The projected controller efficiency of 96
,,^tr.ent should be attainable in the near future.
In mass production power transistors would be matched closely to thetraction motor voltage and amperage, providing highest efficiency atredlsred cost. It also should be possible to integrate traction motor andthe power section of the controller in one unit just as it is done in today'scar alternator reducing the cost and size even further.
84
01
8.2 Description of Concept A6
This propulsion system uses a three-phase ac induction motor forpropulsion power. The drive is through a three-screed transmission andfinal drive gear combined in a transaxle. The arrangement is for afront-wheel drive which allows effective regenerative braking for mostnormal braking situations. Conventional four-wheel hydraulic brakes areused when more rapid braking is required.
The electrical power supplied to the drive motor comes from thebattery and from a flywheel/generator energy unit with the division ofpower from these two sources controlled in such a way as to limit the currentto and from the battery. The electrical energy from these two sources isdelivered at 96 volts do to a three-phase inverter which gives a three-phase ac output of the desired voltage and frequency to drive the inductionmotor or to provide braking by forcing the induction motor to operate asa generator to return energy to the flywheel or battery.
The principal characteristics of this design are summarized in Table26. More complete specifications and drawings are given in Appendix A.The layout of the components are shown in Figure 29.
More complete details of the vehicle configuration and componentsare shown in the following drawings (located in Appendix A):
DRAWING
Fl ywheelHomopolar Inductor GeneratorFlywheel--Dc GeneratorStator-Rotor Ac Traction MotorMotor-Transaxle AssemblyGeneral ArrangementSchematic--Concept A6 (included as
Figure 33)
Losses
DRAWING NUMBER
131D051131 D052131D053131D054131D055131D057131 F056
8.2.1 Current Waveforms and Harmonic
Because of its high cost and complexity the do to ac controller for theac induction motor of the A6 concept has been of major concern. The con-troller consists primarily of a do to ac inverter with a variable fre-quency and voltage output.. The output frequency is controlled to give adesired amount of slip for the induction motor. The desired positiveslip is proportional to the driver-controlled position of the acceleratorpedal and desired negative slip is determined by the driver via the positionof the brake pedal. For a constant air gap flux, the torque of the inductionmotor is approximately proportional to the slip. The output voltage of themotor controller is maintained approximately proportional to the frequencyin order to produce the desired air gap flux in the motor. The outputwaveform of the inverter and the means of controlling frequency andvoltage have been studied.
85
Table 26. General Propulsion System Specification
Design Concept A6
r Curb weight 1400 kg (3218 lbs)Battery weight 556 kg (1226 lbs)Propulsion system weight less battery 178 kg (392 lbs)
Traction Motor
3-phase ac inductionRated power 26 kWBase speed 7200 rpmEfficiency 91%Power factor .84Weight 41 kg (90 lbs)Rated Voltage 75 Vac
Fiber Composite Flywheel
Total stored energy 2.44 MJ(678 Wh)
Maximum speed 46300 rpm
Total weight 16 kg (35.3 lbs)
Flywheel Motor/Generator
Brushless DCF Peak power
Base speed45 kW23158 rpm
Maximum speed 46300 rpm
EfficiencyWeight,
87%20 kg (43.3 lbs)
Transaxle 3-speed
Weight 49 kg (109 lbs)
Controllers - variable voltage and frequency
Rated power 63.5 kVAWeight 52 kg (114 lbs)
Battery/Lead-Acid
Specific energy 40 Wh/kg (18 Wh/lb)Specific power 100 W/kg (45 W/lb)Efficiency 60%
Propulsion System Performance
Range for steady 45 mph cruise 225 km (140 miles)
Range for SAE J227a Schedule D 161 km (100 miles)
Accel-gyration - 10 to 55 mph 15 sec
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The output voltage waveform will not be a pure sinusoidal wave butwill be more nearly a rectangular pulse wave as shown in Figure 30.This wave will contain harmonics which presumably could cause undesirableenergy losses and torque fluctuations. To determine the effects ofharmonic content on energy losses, the rectangular pulse was resolvedinto its Fourier series components which were then used as input voltagefor the motor's equivalent circuit.
In the three-phase motor, the harmonics which are multiples of threewill produce no current, so these may be ignored. Those odd harmonics whichhave a harmonic number that is one less than a multiple of three willproduce a negative slip due to a reverse rotation of magnetic field andthose with a harmonic number one greater than a multiple of three willgive positive slip and forward rotation of magnetic field. To solve forthe current and losses in the equivalent circuit of Figure 31, the valuesof slip and reactances which are frequency dependent must also be solved.For the higher harmonics, the reactances increase substantially and causea significant reduction in the current components.
Table 27 shows the harmonic amplitudes for unity height rectangularpulses of various pulse widths. The magnitude of the fundamental increasesas the pulse width increases. The amplitude of the third, ninth and otherharmonics of multiples of three are shown although they produce no currentin the three-phase c rcuit. The fifth harmonic can be set to zero byuse of a pulse of 72 d or 144°, however, a pulse width greater than 120° isdifficult to accommodate in a three-phase circuit.
For a delta-connected, three-phase motor with a 240 volt* rectangularpulse, the leg voltages for the fundamental and various harmonics are shownin Table 28 for pulses of various widths. The motor current componentsassociated with the voltage harmonics have been computed using the equiva-lent circuit for a wide range,of load conditions. The value of the funda-mental current component varies with loading condition, but the currentcomponents associated with the harmonic are practically independent ofload because the effective impedance of the motor at the high frequenciesof the harmonics is nearly independent of motor torque, is highly reactive,and increases almost linearly with frequency. The current values are shownin the table for the maximum load condition. The table shows that thecurrent components drop off very rapidly as the harmonic number increases.
The power losses associated with the various harmonics are shown inTable 29. The losses for the fundamental are quite large because the motoris at its maximum torque. These losses will decrease as the motor powerdecreases because the efficiency increases at lighter load.
The losses associated with the harmonics remain independent of load.The summation of all the losses due to harmonics are very small for all
pulse widths.
*The 240 volt was convenient tosequently reduced to 96 volt butelusions as all quantities scaleTnP motor losses are independent
ise initially. The system voltage was sub-this does not change any of the basic con-directly with power and kVA held constant.of design voltage.
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The values of the current components in Table 29 are used in con-junction with the power factors of Table 28 and the signs of the Fouriercoefficients in Table 27 to generate a resultant current waveform. Thiswaveform is obtained by simply adding up the harmonic components. Bysuperimposing the current waveform upon the on/off diagram for thesemiconductors in the simplified inverter circuit of Figure 32 the currenthas been resolved into paths through the diodes and switching units(shown as NPN transistors) and a suitable summation of these currentsgave the current to or from the battery.
The average and RMS value of current through the diodes and tran-sistors was found by integrating the waveforms for each unit. Theaverage current from the battery agrees with that calculated on thesimple basis of electrical power to the motor. The average current throughthe diodes agrees closely with Oat calculated simply on the basis of thereactance kVA of the motor being handled by the diodes and the averagecurrent in the transistors on the basis of the resultant kVA of the motor.Improving the power factor of the motor reduces the average current inthe semiconductors.
The waveforms for the current from the battery showed a very largeripple at six times the electrical frequency of the motor. This ripplecould have a very undesirable effect upon the battery. A large commuta-ting capacitor will be necessary to protect the battery from the highfrequency ac current components and to protect the transistors from highvoltage spikes.
8.2.2 Control Circuits
X
The control circuit diagram is shown in Figure 33 with more detailon Drawing 131F056.
i8.2.2.1 Slip Controller
The motor slip is calculated, with the use of a standard divider anda difference amplifier, from the following equation:
ns-ns = n
s
The synchronous frequency (n ) is proportional to the control voltage of aVoltage to Frequency Corivertir (V.C.O.) The rotor frequency (n) is deter-mined by the rotor tachometer. The slip is controlled with feedback tech-niques around an operational amplifier. The slip figure is fed back tothe inverting ,junction while the output controls the V.C.O. Since the out-put frequency of the V.C.O. is the synchronous frequency, any signal on thenoninverting input of the op amp represents a slip command. The slip will
therefore be regulated to a level proportional to this signal.
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The applied motor vnitage varies linearly with frequency to the pointof magnetic saturation. This is accomplished through the use of PulseWidth Modulation (P.W.M.). The Pulse Width is directly proportional tothe synchronous frequency voltage until it reaches the saturation point.
8.2.2.2 Traction Motor Three-Phase Generator
The three-phase generator develops the control signals for , thesix power transistors that drive the traction motor. The signal sequenceis periodic and its frequency is equal to the V.C.O. output frequency. TheP.W.M. signal is imposed on one h.:-lf of the transistors to provide voltagecontrol. A unique feature is that the system also monitors the linevoltage to ensure that any twc common devices will not turn on simultaneously.This allows the conduction angle of th< generator to approach a maximum of1200.
8.2.2.3 Gear Shift Controller
The gear shift controller performs two functions. It determines whento shift and into which gear. It also controls the shifting sequence.The shifting sequence is a function of a six-position counter. The normalmode is position zero at which the slip controller maintains command.A shift command increments the counter to position one which sets theslip to zero, and then increments the counter to position two. Positiontwo maintains the plip at zero, provides a 400 msec pulse to disengagethe gears, and then increments the counter to position three. Positionthree commands the slip controller to synchronize the drive gear withthe selected gear. After synchronizing, the counter is incremented toposition four. Position four provides a 400 msec pulse to engage theselected gear and then increment the counter to position five. Positionfive resets the counter to position zero and relinquishes comet;; y to theSlip Controller.
The incident' of shifting and the intended gear are determined bythe output level of a function between velocity and torque. As thedifference between the signal representing rotor velocity and a signalderived from the slip cross two set points a shift pulse is generated.The output level relative to the two shift points can be decoded to determinethe gear involved. A shifting sequence along with changing gears mustalso offset the slip to maintain an even torque at the wheels. The slipscale factor is also modified to match each gear. This allows themechanical range of the accelerator to remain constant independent of thegear involved.
8.2.2.4 Rotor, Vehicle, and Flywheel Tachometer
Voltages proportional to the speed of the rotor, vehicle, and flywheelare developed using three integrated circuit tachometers.
99
8.2.2.5 Flywheel Mode Control
Current shunts are used to determine direction and magnitude ofcurrent to the flywheel and traction motor/generators. The signalsproportional to the currents are then decoded to determine the mode ofoperation of the flywheel motor/generator. Three modes of operation exist.The first case is when the current to or from the traction motor/generatoris between two specific points. In this mode the battery will supplythe majority of the current while the flywheel is speed-regulated tomaintain a nominal velocity. The second case is when current into thetraction motor exceeds the upper set point. In this mode the flywheelmotor/generator acts as a generator and the excess current to the tractionmotor comes from the flywheel. The final case is when current from thetraction motor exceeds the lower limit. In this mode the flywheelmotor/generator acts as a motor and accepts all excess current from thetraction generator.
8.2.2.6 Flywheel Controller
The flywheel motor/generator is controlled through Pulse WidthRegulation of the field.. An integrated circuit P.W.M. is used at fourkHz to drive the field chopping transistor. The modulator input can bea signal proportional to the current of either the traction or flywheelmotor/generator, or it could be the flywheel tachometer output.Independent of the mode of operation, the fi`eid is reduced to producemotor action and increased to produce generator action.
8.2.2.7 Flywheel Three-Phase Generator
The three-phase generator develops the applied armature voltagerequired to operate the flywheel motor/generator as a motor. As withthe Traction Motor Three-Phase Generator, the developed signal is aperiodic three-phase square wave. The frequency of this signal isdirectly proportional to the rotor speed. The input clock is developedfrom a position wheel that is attached to the rotor. The generator alsomonitors line voltage to ensure that two common devices do not turn onsimultaneously.
The ratio of power from the battery and from the flywheel is.controlledby the voltage of the generator. Raising the generator voltage slightlyabove the battery voltage forces more current from the flywheel and lessfrom the battery. Lowering the voltage during regeneration diverts morecurrent to the flywheel and less to the battery.
8.2.2.8 Flywheel Motor/Ge'nerator Position Sensor
The position sensor is formed from a number of optical sensorsthat sense slots in the position wheel. As the slot passes by the sensor,a digital pulse is generated. The pulses are then combined to form theclock for the flywheel three-phase generator. The output of one of thesensors also serves to input the flywheel tachometer.
1001
61
8.2.2.9 Power Supply
The plus and minus 15 volts are derived from two integrated circuitpulse width regulators. The chopping frequency is ten kHz.
8.2.2.10 Drive Electronics
The drive electronics consists of NPN Darlington transistors anddiodes for the flywheel and generation modes. The transistors that arereferenced to ground are driven directly through current amplifiers whilethe transistors that are referenced to the positive bus are driven fromoptical-isolators through current amplifiers. The optical-isolators arereferenced to a voltage that is 15 volts below the positive bus. Thisvoltage is developed through an integrated-circuit chopping regulator.
8.3 Description of Concept D2
Table 30 summarizes the characteristics of conceptual design D?.Appendix B lists the specifications in more detail.
The conceptual design of components and their layout within the vehicleconfiguration are shown in the following drawings (included in Appendix B):
Drawing Number Title
131DO81 Flywheel with Magnetic Coupling131DO82 3-speed Transaxle131DO84 DC Traction Motor131DO85 CUT131DO86 General Arrangement
This propulsion system shown in Figure 34 uses an electronicallycommutated do motor with a separately excited field for propulsion duringcruise and other light loads and uses power augmentation from a flywheelvia a CVT for acceleration, braking and other high power requirements.The general flow of power is shown in Figure 35. The power from the flywheelis shown flowing through a magnetic coupling which acts to limit the torqueand to permit de-coupling to reduce run-down losses. The power out ofthe magnetic coupling flows through a CVT to the drive motor with theCVT used to provide a speed match and to control the flywheel torque.
The CVT controls the power flow to and from the flywheel. The powerfrom the flywheel can flow directly through , the motor shaft to the transaxleto drive the vehicle. The power from the flywheel normally augments theelectrical power produced by the motor due to current flow from the battery;however, the energy from the flywheel can be returnedto the battery whenthe drive motor is in the generating mode. During regenerative braking,power flows from the drive wheels back into the flywheel via the CVT;however, part of the power can flow back into the battery.
4
Table 30. GENERAL PROPULSION SYSTEM DESCRIPTION
DESIGN CONCEPT D2
Curb weight 1474 kg (3250 lbs)Battery weight 544 kg (1199 lbs)Propulsion system weight without battery 205 kg (452 lbs)
Traction MotorElectronically commutated brushless doRated power 26 kWBase speed 5400 rpmMaximum speed 7800 rpmEfficiency 90.4%Voltage 96 VdcWeight 43 kg (95 lbs)
Fiber-Composite FlywheelTotal stored energy 2.44 MJ (678 Wh)Maximum speed 46300 rpmTotal weight 10. kg (35.3 lbs)
CVTPlanetary cone typeMaximum power 34 kWMaximum/minimum speed input 46300/15400 rpmFull load efficiency 94%Weight 71 kg (157 lbs)
Magnetic CouplingMaximum power 36 kWBase speed 23200 rpmWeight 9 kg (20 lbs)
Transaxle - 3-SpeedWeight 50 kg (109 lbs)
Controller9-phase chopperRated power 29 kWWeight 16 kg (34.8 lbs)
Battery - Lead-AcidSpecific energy 40 Wh/kg (18 Wh/lb)Specific power 100 W/kg (45 W/lb)Efficiency 60%
Propulsion System PerformanceRange for steady 45 mph cruise 223.7 km (139 mi)Range for SAE J227a Schedule D 160.9 km (100 mi)Acceleration 0 to 55 mph 15 sec
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The main power flow is to and from the drive wheels f ^r propulsionand braking. This power flow is shared by the battery and flywheel withthe battery normally supplying steady cruise power and the flywheelproviding extra power for acceleration and braking. A secondary powerpath is for the flow of power between the flywheel and battery. Thissecondary path is primarily used for energy management'to prevent theflywheel from over charging on a long downgrade or from running down froma succession of accelerations.
The power flow to and from the flywheel is controlled by the CVT,by changing the speed ratio to force the flywheel to slow down and giveup part of its kinetic energy or to speed up to accept energy. The flowof power from the motor is controlled either by field current control orarmature current control depending upon the speed of the motor. Abovethe base speed of the motor,field current is used to provide variablecounter emf of the motor. Below the base speed, armature current controlis used to provide variable torque for, the motor.
The total power to the drive wheels is essentially the sum of thepower from 'the drive motor and from the flywheel so the power flow fromboth units must be coordinated to give the total power flow to satisfythe driver input request. The driver input is mainly from the acceleratorpedal or brake pedal and from each what the driver requests is essentiallya positive or negative torque. For the flywheel to provide a specifictorque output requires a-specific rate of Change of flywheel speed. Thiscan be forced by a specific rate of change of CVT ratio. 'To maintain acontinuous torque requires a continuous change in ratio. The actuatorthat forces this change in ratio is controlled in response to a torquesignal generated from the measured slip in the magnetic coupling.
The motor torque is essentially proportional to the product of thearmature current and the field flux. At speeds below the base speed,the field flux is ,constant so control of armature current provides control ofmotor torque. Above the base speed, the field is weakened to give lowercounter emf to cause an increase in armature current. Torque control inthis region can be obtained by control of field current if 'the armatureand field current product 'is monitored.
The armature current flows through an electronic commutation unitwhich also provides chopper control of armature current below the motorbase speed. This unit uses a motor shafc position sensor to control thetfi-ning for the turn-on and turn-off of the semiconductor switches.
The motor armature has nine separate coil circuits each of whichi': switched electronically. The timing for the circuits switching is,,own in electrical degrees in Figure 36. The duration of each pulse isabout 1200 electrical and the phase lag is 40 0 . At any one time, threeCurrent paths are active. A possible circuit is shown in Figure 37.During the time that transistors 1, 2 and 3 are on, transistors 5, 6, 7and 8 are on with 8 turning on as five turns off.
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A simplified circuit showing the operation of the commutation unitduring drive and generation modes is shown in Figure 38. This simplifieicircuit shows coils 1 and 5 with the other seven coils left off forclarity. Positive current for coil 1 flows through Q1 or Dla and negativecurrent through Qla or Dl. Below the base speed, motor power is controlledby chopping the armature current. As shown, Q1 and Q5 act as choppers
with Dla and D5a acting as freewheel diodes. When Q1 is chopping thecurrent for ,coil 1 the current path back to the battery is through eitherQ5a, Q4a, Q6a or Q7a depending upon the shaft position and when Q5 ischopping the return is via Q2a, Qla, Q9a or Q8a.
During the generator mode of operation when the speed is less thanthe base speed, there is inadequate voltage for recharging the battery,and the commutation unit must also act as a chopper controlled voltagebooster. Current to recharge the battery flows through D1 and D5. Duringthe portion of the motor cycle when D1 provides the recharge path, Qlaacts as a booster chopper. While D5 provides the recharge path, Q5a actsas a booster chopper.
A variety of signals are needed for con y ' •ol of the commutation unit.The motor shaft position determines the timing for gross switching ofthe semiconductors. The motor speed and positive or negative powerrequirements determine the chopper on-off ratios.
The number of semiconductor switches required for the electronicallycommutated motor circuit is 18 or nine times that requires for a conventionalchopper used with a mechanically commutated motor; however, three sets of
switches simultaneously carry current so that the current ratings ofthe semiconductors are lower by about one third than those for a conventionalchopper.
8.4 Flywheel Size and Energy Rating
The flywheel examined during the preliminary analysis and designtrade-off studies had a total kinetic energy of 6.84 MJ (1900 Wh) tocontinually provide a 2.52 MJ (700 Wh) energy reserve for braking oracceleration. For a 1642 kg (3620 pound) vehicle test weight, the chargein kinetic energy corresponds to the vehicle's potential energy change dueto an elevation change of 152 m (500 feet). This is not an unusual elevationchange in a hilly area, but could represent an unusual energy change forlevel terrain. For the vehicle operated mostly on level terrain, anexcessively large flywheel is an undesired burden. Consequently, it wasdecided that the maximum energy change could be set to that required forthe Federal Urban Driving Cycle (FUDC). Examining the A6 concept over the"D" cycle and FUDC showed a maximum energy swing of .412 MJ (114.34 Wh) forthe "D" cycle and .749 MJ (208 Wh) for the FUDC. An energy swing of .9 MJ(250 Wh) was selected as a new design criteria for the energy buffer.
108
Generator modebelow base speed
Q5A Chopper
D5 return path
Q5 Chopper
D5A FWD
Drive Mode
Q1 ChopperD1A FWD
Q1A Chopper
D1 return path
Figure 38. Electronically Commutated Motor Switches
Transistors Provides Chopping for Driveand Generator Modes and For Commutation
109
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Figure 39 shows the energy swing on either side of the operating point andshows that the total kinetic energy at the maximum flywheel speed is2.44 MJ (678 Wh). This results in a smaller flywheel than initiallyconsidered based on the hilly terrain of the San Francisco Bay Area. Thesmaller flywheel spins at higher speed and allows the generator used withthe flywheel to be smaller and of lighter weight. The smaller flywheelis easier to accommodate in the available vehicle space and has a lowergyroscopic moment.
The flywheel/generator unit is shown in Figure 40. The combined weightis 35.6 kg (78.6 pounds) for the stored energy of 2.44 MJ (678 Wh) andpower level of 48.5 W.
8.5 CVT Types
Several types of CVTs were examined. It seemed desirable to have theinput shaft for the CVT operated at flywheel speed. No CVTs are availablewhich can accept a 46,000 rpm input. A new design of a traction-type CVTseems possible and desirable. The high speed of the input shaft wouldallow low torque. The high speed/low torque combination seems like anideal combination for a traction-type device. The Nasvytis type speed (ref. 7)reducer appears to work well in the high speed/low torque region. Thealternative appears to be the development of a high-speed CVT or the use ofa first-stage speed reducer such as the Nasvytis type device to bringthe speed and torque to a value that can be accommodated by CVT designedfor the more conventional speed domains.
In any case, it appears necessary to provide a means of decouplingthe flywheel from the CVT and for providing a limit to the torque transmittedto prevent damage to the CVT if excessive overloads were to occur. Anelectro-magnetic coupling using the limited slip induction design ratherthan a synchronous design is simpler to control and can satisfy therequirements for limiting the maximum torque through control of fieldexcitation current. The design can also provide a hermetic vacuum barrierfor the flywheel housing.
If the high-speed type CVT is to be developed, it would have to havehigh efficiency and be light weight to be acceptable. Several types ofdesigns were considered. A planetary ball and cone design appeared to haveinadequate torque and was rejected. Multiple-tapered cones with adequatecrown to reduce "spin torque" and viscous drag appear to hold some promise.
Layout drawings using hypothetical CVTs of the high-speed and conventionalspeed types were prepared. It appears that adequate space is availablefor either type if they can be developed to give acceptable efficiency andlife.
8.6 Vehicle Performance
The vehicle weights, range and energy consumption are summarized inTable 31.
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Table 31. Candidate Weight/Performance Comparison
F
Candidates
Weights, kg (1bs) A6 D2
f cle Curb Weight 1460 (3218) 1474 (3250)
Battery Weight 556 (1226) 544 (1199)
Axle 27 ( 59) 27 ( 59)
Transmission 23 ( 50) 23 ( 50)
Motor 41 ( 90) 43 ( 95)
Controller 52 ( 115) 16 ( 35)
Flywheel 16 ( 35) 16 ( 35)
Generator 19 ( 43) --
CVT -- 81 ( 178)
Propulsion System Weight 178 ( 392) 205 ( 452)
Energy Per Mile, MJ/km (Wh /mi)
f "D" Cycle
From Battery .472 ( 212) .469 ( 210)
! From Wall plug , .79 ( 353) .783, ( 350)
Steady 45 mph .37 ( 165) .365 ( 163)
i Range, km (mile)
"D" Cycle 161 ( 100) 161 ( 100)
Steady 45 mph 228 ( 142) 224 ( 139)
I
113
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From the table it can be seen that the vehicle curb weights and thebattery weights are within one percent of each other. The weights of thepropulsion systems on the other hand show a fifteen percent or 60 pounddifference in weight. This difference is mainly due to the greater weightof the CVT, 80.5 kg (177.5 lbs) versus 38.2 kg (84.3 lbs) weight of thegenerator/controller combination. Because of the better (anticipated)efficiency of the CVT, the energy consumption over the SAE J227a Schedule Ddriving cycle is less for Concept D2 than for A6, and only 544 kg (1199 lbs)of batteries are needed partly offsetting the higher propulsion systemweight.
Both concepts meet all range and acceleration goals but both conceptsfailed to meet the Wh/mile wall plug energy consumption goal with lead-acidbatteries. To meet the 250 Wh/mile wall plug energy consumption goalwith lead-acid batteries, range has to be sacrificed or the efficienciesof the propulsion system components pushed close to 100 percent.
With nickel-zinc batteries, it is possible to meet both ran a andenergy consumption goals. However, the higher life cycle cost oT anickel-zinc battery s ystem more than offset the gain in energy consumption.
8.7 Propulsion System Cost Comparison
The life cycle cost of the conceptual designs are summarized inTable 32. .
Guidelines for life cycle cost calculations were provided by NASALewis Research Center and appear in Appendix D. In addition to the lifecycle cost guildelines, the following specific information regarding batterycost and life were provided by NASA Lewis and are listed in Table 4.
The number of miles attainable per 80 percent discharge is 80 mileswith battery weight adjusted to give a range of 100 miles per full discharge.For the specific number of 80-percent discharges (Table 4), this resultsin a 6.4 year life for lead-acid and a four year life for nickel-zinc batteries.
Today's prices (1979) were converted into 1976 dollars by using anaverage eight percent inflation rate.
On critical high technology units where no mass production costfactors are available, cost was estimated based on Task III Conceptual Designsand drawings. The critical units are:
FlywheelHomopolar InductorContinuously Variable Transmission (CVT)Electronic Controllers
On items where existing technology can be applied current prices orunit prices were used. These current prices were then subsequently.
reduced to 1976 dollars.
More detailed information on operating/life cycle cost appears in Tables
Dl to D9 in Appendix D.
114
r
Table 32. Propulsion Systems - Cost Comparison
A6
Battery Acquisition Cost 1301
Propulsion System Acquisition Cost
(with battery) 3175
Annualized Acquisition Cost 317.5
Discounted Annual Cost @ 2%Discounted Rate
Electricity
Repair & Maintenance
Battery Replacement
Power Train
Battery Salvage
Discounted Annual Operating Cost
Present Value of Life Cycle Cost/yr
Present Value of Life Cycle Cost/km (Cost/mi)
126.6
61 .5
99.8
-3.7
-26.0
257.6
575.0
.036(.058)
D2
1273
3123
312.3
125.4
102.8
97.7
-3.6
-26.0
296.
608.0
.038(.061)
115
II
9. DISCUSSION OF RESULTS
The preliminary analysis of 28 candidate propulsion systems and thesubsequent design analysis of the five most promising concepts show clearlythat a relatively large amount of on-board energy storage such as batteriesis required to provide the desired range and that a power booster elementsuch as a flywheel is desirable to provide peak performance especiallyas the batteries near their discharge point. The analysis also shows thedesirability of efficient regenerative braking capable of handling briefperiods of very high power. The effects of returning braking energydirectly to the battery at high power levels is not known wit" ertainty. (Ref. 18)It is possible that brief high power "shocks" could have a .,vneficialeffect on battery life and output, (Ref. 29) but it is likely that agreater efficiency of energy recovery can-be achieved by returning thebraking energy to a power booster such as a flywheel. (Ref. 30, 31)
There are two significant reasons for favoring the return of brakingenergy to a flywheel rather than to the battery. One is that the charge-discharge efficiency of the battery is estimated to be as low as sixty percentfor lead-acid and seventy percent for Ni-Zn. The other is that it ismuch more efficient to deliver braking energy directly to the flywheelthan indirectly to it by way of the battery as additional power conversionsteps are required.
The study also shows that high-speed, light-weight motors are beneficialeven though they wil'i require multi-speed transmissions to provide theincreased torque required at the drive wheels at low vehicle speed. Themulti-speed transmission appears to provide an efficient and cost-effectivemeans of producing high torque at the drive wheels. The alternative is touse a direct drive with a larger and more expensive propulsion motor. Thealternative is technically less attractive in terms of cost, weight andefficiency, but may be more attractive in the market place. The absence ofshift points and possible "jerk" could be an important selling point, buta difficult one to evaluate.
The trade-offs between do drive motors and ac drive motors werestudied. The main drawback of present do motors is their mechanicalcommutation. The brushes have friction and wear problems as well as avoltage drop. At high speed, commutation problems such as sparking atthe brushes and flashover limit the output of a given size armature. Abrushless do motor could eliminate these problems of the commutator, butreplace it with the problems of an electronic commutation circuit and makesthis type dc.motor similar in cost and complexity to the ac motor forvehicle propulsion. Both do and ac type motors have similar weights,efficiencies and cost.
117..
l 9
The electronically-commutated do motor is essentially a synchronousmotor with an inverter triggered by a shaft position sensor, which locksthe inverter frequency and phase to the motor speed and shaft position.By forcing the frequency and phase to follow the motor rather than vice-versa,the synchronous motor then possesses all the characteristics of a separately-excited do motor. The fact that the field current for this type do motorcan be separately controlled provides it with a significant advantage overthe induction motor especially for its operation as a generator duringregeneration.
The electronically-commutated do motor always maintains a good phaserelationship between the applied voltage waveform and the generated counteremf; whereas, the induction motor will sometimes operate at a very poorpower factor with sub^Aantial mismatch of the applied voltage waveformand the generated counter emf. Consequently, over much of the operatingrange the peak-to-average current ratio for the semiconductor devices forthe inverter for the induction motor will be higher than those for theelectronically-commutated do motor. In the final analysis the suitabilityof the electronic conversion and control units will be the deciding factor.The added cost of the features required to insure regeneration with aninduction motor could wipe out any cost savings due to the squirrel cagerotor.
Initially, it was thought that the current controllers andinverters should use SCRs rather than transistors for switching. For agiven power rating an SCR controller costs less than one using transistors;however, the turn-off times for SCRs are too long to permit the desiredswitching rates.(Ref. 28) Chopper frequencies of about four kHz appear to be ideal.Much lower freouencies will require excessively large reactors to filterout undesirable current ripple. Much higher frequencies would require
reactors with special core materials to prevent excessive eddy currentlosses. Such reactors would be bulky or costly. Presently availabletransistors should be considered for the design initially, but as moreefficient types such as field effect devices (Ref. 32) become available theseshould be substituted. Better and cheaper transistors are vitally important tothe development of electric vehicles.
Initially., it was thought that systems using higher voltage would bemore attractiv-,j i;nan those using lower voltage, because the former wouldhave lower current for a given power. However, other factors such assafety, battery reliability and maintenance indicate very high voltagesare not necessarily desirable. A higher voltage would require a largernumber of small cells with a corresponding increase in maintenance. Higherdo voltages increase the danger of electrical arcs and increase the shockhazards. The risks of arc and electrocution go up rapidly as the voltageis increased above 100 volts dc. It is true that the use of higher voltageswould reduce the required current rating of the semiconductors and thusreduce their cost; however, the cost savings would not compensate for theincreased safety hazards and decrease in battery reliability. Moreover,the power losses in semiconductors operating in a 96 volt do system can be
acceptably low.
Several items are crucial to the design concepts. These are the
following;
118
t
1. High-speed flywheel subsystems
2. High-speed homopolar inductor/generator and inverter/controllersystem
3. High-speed, light-weight, three-phase induction motor andinverter/controller
4. High-speed, light-weight, electronically-commutated, separately-excited do motor including electronics.
5. High-speed CVT suitable for use with a flywheel energy input andsuitable ratio-controller unit
Of these, the item of greatest developmental risk appears to be theCVT. The flywheel development may at first appear to be equally risky;however, the risk involves only how much energy can be stored for a givenweight. That a flywheel can store energy and that adequate power canbe generated is not in doubt. The questions are how much power. energy,weight and cost. In contrast, the questions for the CVT is whether it canbe done with 2nX reasonable life, weight or cost. Will a continuouslyvariable traction device operating at high speed have adequate torque andefficiency? Will the churning losses and slippage be excessive? Withouttests and experimentation these questions can not be answered.
If they were developed, their service and maintenance costs areexpected to be higher than those for the electrical conversion system.The extra cost of service and maintenance could offset any potential gainfor the CVT-based propulsion systems; however, the projected overallefficiency for the propulsion systems using the CVTs are higher , than thosewith the flywheel/generator systems. Considering the potential advantages,it is too early to positively conclude that the service and maintenancecosts would completely offset the energy savings. It should be recognizedthat such a development program may not succeed in providing a unit at anacceptable cost.
Some work is presently underway on subsystems using various flywheeldesigns and much lower energy levels. The work should be expanded to covera wider range of energy and flywheel designs.
A variety of types of power boosters to provide peak power performanceare possible. It appears that a flywheel-type booster is the most attractivetype. Using a fiber-composite flywheel, such a unit can have very highspecific power and specific energy without an excessive gyroscopic moment.When used with a generator for converting its kinetic energy to*,electricalenergy, high conversion e tificiencies can be obtained and the power flow toand from the flywheel can be easily controlled. The developmental risks forsuch a system are not excessive. G
The optimum stored energy in the flywheel is dependent upon terrainas well as the velocity profile of the driving cycles. A vehicle operatedon hilly terrain could benefit from a larger flywheel energy storage than one
119
operated on level terrain. On level roads, the ability to absorb or releaseabout 250 Wh of kinetic energy will suffice for most anticipated drivingconditions without danger of flywheel rundown or overspeed. This requiresa total energy swing of 500 Wh.
Flywheels used in cars should be safe, inexpensive and have highspecific energy (MJ/kg (W-hr/lb)). Several flywheel designs likeshaped steel disk and multi-ring fiber composite have been investigated.As can be seen from published reports (ref. 19) the flywheel specificenergy of fiber composites is 1.6 - 4 times higher than for shaped steeldisk designs. In order to store the same amount of energy in a shapedsteel disk, the shaped steel disk flywheel would weigh more than twiceas much as a fiber composite flywheel. The greatest penalty lies inthe heavier containment structure (approximately five times) needed forsteel flywheels to give adequate protection.
The maximum wall plug energy for SAE J227a Schedule D (.559(250) MJ/km(Wh/mi)) requirement, with a given battery efficiency of sixty percent(lead-acid) and an assumed charger efficiency of 85 percent is .285 (127.5)MJ/km (Wh/mi) with vehicle/battery characteristics as listed in Tables2 and 3. For a propulsion system efficiency as high as 86 percent, thewall plug energy consumption was computed 65 percent higher than the targetof .559 (250) MJ/km (Wh/mi). With lead-acid batteries, it would be verydifficult to fulfill this requirement. With nickel-zinc batteries,being lighter and more efficient, the wall plug energy requirement can bemet.
120
10. CONCLUSIONS
The preliminary analysis, design trade-off study and conceptualdesign lead to several general conclusions about the nature of' an advancedpropulsion system designed for a range of 100 miles of repeated SAE J227aSchedule "D" cycles.
1. There is no identifiable single "best" design to achieve thedesired range ane performance objectives, but rather a multitude of designsare possible.
2. If ISOA lead/acid batteries with a specific energy of 40 Wh/kgare used, a total battery weight of approximately 1200 pounds will berequired, However, if nickel/zinc (Ni/Zn) batteries with a specificenergy of 80 Wh/kg were used only 490 pounds would be required. Unfortunatelythe nickel/zinc batteries have shorter life and are much more expensivethan the lead/acid batteries.
3. The cost of the initial supply of batteries would be about 22percent ,higher for Ni/Zn and their replacement costs over the life. of thevehicle are nearly double that for lead/acid.
4. The addition of a multi-speed transmission is worthwhilebecause in today's technology a suitable transmission would be lightweight and reasonably 'inexpensive compared to the weight and cost increaseassociated with the increase in motor size required for direct drive.
5. Two general types of traction motors appear attractive for anadvanced propul sior system in terms of their efficiency, specific powerand potential for mass production. These are the multi-phase inductionmotors with squirrel cage rotors and the multi-phase synchronous motors ofvarious designs,including the claw-power or Lundel design, the homopolarinductor design and the more conventional designs using either cylindricalor salient pole rotors with slip rings and brushes..
6. High-efficiency controllers capable of regenerative operationwill be required, The waveforms needed for efficient inverter./rectifieroperation will require pulse-width modulation with switching speeds inexcess of that practical now with SCRs. High-power transistors with lowlosses such as the field effect devices now being developed appear to benecessary.
7. The study of candidates using CVTs to mechanically convertflywheel kinetic energy into vehicle propulsion, indicate that such unitsare potentially practical although they are probably heavier than theelectrical conversion system. Much development work is required beforesuitable CVTs can be made available for this purpose.
121
I
M'
11, RECOMMENDATIONS
The program has identified and examined a variety of attractive
concepts for advanced propulsion systems which appear capable of significant
performance improvements with 'little or no cost penalty, but do have somedevelopmental risks. The field has been narrowed down to the most attractive
concepts which we recommend for further design and developmental efforts.
1. The least developmental risk with high benefits is the A6 Concept.It is recommended that a functional model of the propulsion system bedesigned, built and tested to verify the projected characteristics.
2. A detailed design for the concept A6 flywheel/generator subsystemand its electronics should bo pursued in conjunction with developments infiber-composite flywhee;s, bearings and vacuum vessels.
3. Tests and experimentation should be undertaken in an effort to
develop a suitable CVT, and to confirm its probable cost and maintenancerequirements.
4. The development of high-power transistors to operate in thevicinity of 100 volts do should be encouraged.
5. Concurrent with the design of the functional model of the A6propulsion system, there should be ongoing work on the development of an
electronically-commutated, separately-excited do motor suitable for
vehicular propulsion. This effort should concentrate on a high-speedmotor of 26 kW continuous power to operate with a 96 volt do input.
f
123
hL _ ....
12. REFERENCES
1. 1979 SAE Handbook, Part 2, Section 27.07.
2. Straughn, A. and Dewan, S. B., "Power Semiconductor Circuits," JohnWiley & Sons, 1975.
3. Robertson and Black, " Electric Circuits and Machines," D. Van NostrandCompany, Second Edition, 1957.
4. Clerk, R. C., "An Ultra-Wide-Range High-Efficiency Hydraulic Pump/Motor Power Transmission," (1977 Flywheel Technology Symposium Proceedings,October, 1977, cosponsored by DOE, NTIS # CONF-77 1053, UC-94b,96.)
5. Frank, A. A., et al, "Flywheel-CVT Systems for Automotive and TransitPropulsion Systems." (1977 Flywheel Technology Symposium Proceedings,October, 1977, cosponsored by DOE, NTIS # CONF-77 1053, 00094b,96).
6. "State of the Art Assessment of Electric and Hybrid Vehicles," Dif-ferentials, Transmissions, pp 157-164, January, 1978, DOE Ref. HCP/M1011-01 .
7. Loewenthal, S. H., Anderson, and Nasvytis, A. L., "Performance of aNasvytis Multiroller Traction Drive," NASA Technical Paper 1378,AVRADCOM Technical Report 78-37.
8. "Van Doorne Steel Belt Transmission," Machine Design, June, 1976.
9. Hughson, D., et al, "Continuously Variable Vehicle Transmission," Dec., 1977,Final Technical Report, C00-2674-16, U. S. DOE Contract No. E4-76-C-02-2674.
10. Hewko, L. 0., Rounds, F. G., Jr., and Scot, R. L., "Tractive Capacityand Efficiency of Rolling Contacts." Rolling Contact Phenomena, J. E.Bidwell, ed., Elsevier Publ. Co., 1962, pp. 157-185.
11. Raynard, Arthur E., "Advanced flywheel Energy Storage Unit for a High-Power Energy Source For Vehicular Use," Proceedings of the 1978 Mechanicaland Magnetic Energy Storage Contractors Review Meeting, DOE No. COINT-78 1046.
12. Rabenhorst, David W., "Composite flywheel Development Program: FinalReport," APL/JHV SDO-4616A, April, NSF Grant No. AER 75-20607.
13. Younger, F. C., et al,"Conceptual Design of a Flywheel Energy StorageSystem," Sandia Report No. Sand 79-7088.
14. Togwood, D. A., "An Advanced Vehicular Flywheel System for the EP.DAElectric Powered Passenger Vehicle," 1977 Flywheel Technology SymposiumProceedings. 0
u;._ 125
^.T
'I
w
15. Lightband, D. A. and Bicknell, D.A. , "The Direct Current Traction Motor,"London Business gooks, Limited, 1970.
16. "Electrical Steel Saves Energy," Machine Design, September, 1977.
17. Satchwell, D. L., "High Energy Density Flywheel," Proceeding of the1978 Mechanical and Magnetic Energy Storage Contractors Review Meeting.
18. Lawrence Livermore Laboratory, "The Rattery Flywheel Hybrid Electric
Power System for Near-Term Applications," Volume 1, System Description,April 15, 1976.
19. Behrin, E., et al, "Energy Storage Systems for Automotive Propulsion,"
1978 Study, UCRL-52553, Volumes 1 and 2, December, 1978.
20. Agarwal, P. D., "The GM High-Performance Induction Motor Drive System,"IEEE Transactions on Power Apparatus and Systems, February, 1969.
21. Gosden, D., "An Experimental Electric Car Using an Induction Motor
Drive," Electrical Engineering Transactions, the Institution of Engi-neers, Australia, 1976.
22. Pollack, J.J., "Advanced Pulse Width Modulated Inverter Techniques,"
IEEE Transactions on Industry Application, April, 1972.
23. Private Communications with Battery Manufacturers Representatives:
Mr. Hopewell, Eagle Picher Mr. D. Sangria, Trojan
Mr. Hartmann, Gould Mr. J. Heiser, H.P.S.
Mr. C. Steeber, Varta Mr. T. Galisano, Chloride
Dr. Seiger, Yardney
24. Salomon, K., "Peripheric Equipment for Reducing Maintenance of Elec-tric Vehicle Lead-Acid Batteries," Fourth International Symposium on
Automotive Propulsion Systems, Volume IV, Session 8 to 10.
25. Daiziel, Charles F., "Electric Shock Hazard," IEEE Spectrum, February,
1 972 .
2E. Day, J. 0., et al, "A Projection of the Effects of Electric Vehicles on
Highway Accident Statistics," SAE Paper 780158, SAE Congress and Expo-
sition, Detroit, Michigan.
27. Kleronomous, C. C., and Chitwell, E. C., "Determining Dynamic Impedancein a Grounding Conductor," 1979, IEE Industrial and Commercial Power
Systems Conference Record.
28. Brusaglino, G., "Fiat Electric City Car Protype," Fourth International
Symposium on Automotive Propulsion Systems, Volume IV, Section 8 and 10.
126
C
29. Vinal, W. G., "Storage Batteries," p 337, John Wiley & Sons, Inc,.,Fourth Edition, 1955.
30. Davis, D. D., et al, "Determination of the Effectiveness and Feasibilityof Regenerative Breaking Systems on Electric and Other Automobiles,"Volume 2, Design Study and Analysis, October, 1977, p 86, UCRL-52306.
31. Kasama, Rygji, et al, "The Efficiency Improvement of ElectricVehicles by Regenerative Braking," SAE Paper 780291, 1978, SAE Congressand Exposition, Detroit, Michigan.
32. Slater, N., "Power Semiconductors," EET Special Report, pp 39-51, August,1979.
33. "Electric and Hybrid Vehicle Performance and Design Goal DeterminationStudy, Final Report," General Resea rch Corporation, August, 1977.
34. Frank, H. A. and Phillips, A. M., "Evaluation of Battery Models forPrediction of Electric Vehicle Range," JPL Publication 77-29, August,1977.
6
127
APPENDICES
APPENDIX A - ADVANCED ELECTRIC VEHICLE PROPULSION SYSTEM, DESIGN CONCEPT: A6
APPENDIX B - ADVANCED ELECTRIC VEHICLE PROPULSION SYSTEM, DESIGN CONCEPT: D2
APPENDIX C - MODELS FOR PROPULSION SYSTEM COMPONENTS
APPENDIX D - GUIDELINES AND BACK-UP INFORMATION FOR COST CALCULATIONS
APPENDIX E - COMPUTER FLOW CHART AND PROGRAM
^?R^C^DIPIG T'1.^'; I?y r^^Ir, NOT ^II^MI^A
4
129 0 1
PRJ3CEDJNG 17,(=1; Bl,At'K NOT FT.LMED
APPENDIX A
ADVANCED ELECTRIC VEHICLE PROPULSION SYSTEM
DESIGN CONCEPT: A6
GENERAL DESCRIPTION:
Flywheel buffered electric propulsion system using an ac inductionmotor as a traction motor and a flywheel coupled to an electricalgenerator to provide a power boost to augment the battery power foracceleration and regenerative braking.
131 6 1
General Propulsion System Specification
Design Concept A6
Curb weight 1400 kg (3218 lbs)Battery weight 556 kg (1226 lbs)Propulsion system weight less battery 178 kg (392 lbs)
Traction Motor
3-phase ac inductionRated power 26 kW
Base speed 7200 rpm
Efficiency 91%
Power factor .84Weight 41 kg (90 lbs)Rated Voltage 75 Vac
Fiber Composite Flywheel
Total stored energy 2.44 MJ(678 Wh)
Maximum speed 46300 rpm
Total weight 16 kg (35.3 lbs)
Flywheel Motor/Generator
' Brushless DCPeak power
E Base speed
45 kW23158 rpm
` Maximum speed 46300 rpm
EfficiencyWeight
870%,20 kg (43.3 lbs)
Transaxle 3-speed
Weight 49 kg (109 lbs)
Controllers - variable voltage and frequency
Rated power 63.5 kVAWeight 52 kg (114 lbs)
Battery/Lead-Acid
Specific energy 40 Wh/kg (18 Wh/lb)Specific power 100 W/kg (45 W/lb)
_ Efficiency 60"^
Propulsion System Performance
Range for steady 45 mph cruise 225 km (140 miles)
Range for SAE J227a Schedule D 161 km (100 miles)Acceleration - 10 to 55 mph •15 sec
132
4
0i
TRACTION MOTOR SPECIFICATION
Design Concept A6
TYPE: 4-pole, 3-phase induction motor cooled by thermostatically-controlled blower* squirrel cage, f = 300 Hz @ 9000 rpm
Rating
Power
Continuous 26000 watts
Peak (30 seconds) 50000 watts
TorqueContinuous 41.2 Nm(30.42 lb-ft)Peak 96.2 Nm (70.99 lb-ft
Base speed 7200
Maximum speed 9000
Line voltage 74.85 ac
Line currentContinuous 263 A
Peak (5 sec) 640 A
Peak (30 sec) 600 A
Power factor (nominal) 84%
Efficiency (nominal) 91%Slip 2%
Number of rotor slots 28Number of stator slots 36
Dimensions mm in
Housing, O.D. 254 10
Housing, I.D. 220 8.68
Stator laminations, I.D. 159 6.25
Stator slot depth 23 .90
Stator slot width 6 .25
Stator core stack length 89 3.5
Air gap diameter 158 6.25
Shaft diameter 47 1.88
Shaft length 292 11.5
Rotor slot width 3 .125
Rotor slot depth 6 .25
Bearing O.D. 89 3.5
*Weight, power and cost of blower are included in motor,
F
controller
weights, losses and cost.
133
C"-
N'
TRACTION MOTOR SPECIFICATION - Con't
Weights kg lbs
Stator iron 12.9 28.5
Stator copper 7.9 17.5
Rotor iron 8.6 19.
Rotor copper 1.6 3.5
Shaft 2.3 5.
Bearings .4 1.
Aluminum housing 3.1 7.
Aluminum end bells 3.4 7.5Miscellaneous hardware .4 1
Total Unit Weight ^w46.6 90
Winding description
Stator: Two layer, short pitch winding at 7/9, two coilsides/slot
Rotor Copper squirrel cage
Losses at rated power
Ohmic 1717 watts
Hysteresis 128 watts
Eddy current 257 watts
Rearing friction 231 watts
Windage 231 watts
Total 2564 watts
4
134
c
01
K
BATTERY TO MOTOR CONTROLLER
DESIGN CONCEPT A6
TYPE: Variable voltage, variable frequency, 3-phase pulse-width modulatedinverter
Ratings
I .-.VA rating, 30 seconds 63.5 kVAkVA rating, continuous 45 kVAVoltage
Input 96 VOutput 75 V
Output current, 50 seconds 600 AOutput current, continuous 263 AOutput frequency 1-300 HzPulse width modulation frequency 4000 Hz
Power Loss
I
@ 60 kVA 2300 W
Efficiency
@ 60 kVA 96 l
Cooling Method
*Forced air cooling
Weight
29.4 kg (65 lbs)
Control Method
Positive slip requirement specified by driver via accelerator pedalposition.
Negative slip requirement specified by driver via brake pedal position.
Voltage controlled as linear function of frequency via control of on/uff
4 1ratio of pulse width modulator.
*Power of blower (100 watts max) is included in motor and controller
losses.
13561
FLYWHEEL
DESIGN CONCEPT A6
TYPE: Ri-annulate rim fiber-composite
Maximum speed
Maximum stored energy
Available energy for a 3:1 speed range
Specific energy
Flywheel dimensions
Inner ring, S-2 glass/epoxy
I.D.O.D.
Outer ring, Kevlar 49/epoxy
I.D.
O.D.
Height
Hub - aluminum with kevlar reinforcement
Kevlar O.D.I.D.
Aluminum hub I.D,
Weights
RingsSpokesHub
Balancing weightsTotal
Housing
Total
Vacuum
Bearings
Seals - hermetically sealed
46316 rpm
2.44 MJ (679 Wh)
2.17 MJ (603 Wh)
64.3 Wh/kg (29.18 Wh/lb)
MM in
253 9.99303 11.93
303 11.93362 14.25
99 3.88
140 5.75127 4.79
111 4.39
kg lbs
8.4 18.52
.47 1.031.60 3.53.09 .19
10.56 23.27
5.44 12.00
16.00 35.27
Ball bearings
r
136
0
FLYWHEEL MOTOR-GENERATOR
DESIGN CONCEPT A6
TYPE: Brushless, dc, homopolar inductor design.Number of poles = 4 .
RatingPower
ContinuousPeak
TorqueContinuousPeak
Base Speed
Maximum SpeedEfficiency
VoltageCurrent
Continuous
Peak
Number of Phases of Armature Winding
Frequency
Dimensions,Rotor, O.D,Rotor, flux return path diameter
Armature Stack LengthArmature Slot DepthArmature Slot Width
Armature, O.D.Field Coil O.D.Field Coil I.D.
Overall Length
Weights,
RotorArmature IronArmature Copper
Field Pole 'IronField Coil Copper
Bearings
Miscellaneous
Total Unit Weight
23 kW
45 kW
8.08 Nm (7.00 lb-ft)
18.50 NM (13.69 lb-ft)23158 rpm
46316 rpm87%96 Vdc
276560
3
1544
mm in
94.9 3.7457.1 2.2565. 2.5620.3 .85.1 .2
157.2 6.19
94.7 3.73
57.1 2.25139.9 5.51
kg lbs2.9 6.3
4.8 10.63.8 8.55.5 12.22. 4.4.3 .6.3 .6
19.6 43.2
137
01
Flywheel Generator
Page Two
Winding description
Armature lap winding and equalizing connections
Field - Concentric wound
Losses at 23000 watt output 2990 watts
Ohmic 2489 watts
Hysteresis 167 watts
Eddy current 167 wattsGearing friction 167 watts
Power needed to circulate oil is included in the Ohmic losses.
138 1
HIGH SPEED GENERATOR CONTROLLER
DESIGN CONCEPT A6
TYPE: Variable voltage, 3-phase electronic commutation with chopper
field circuit and armature control
Ratings
kVA rating, 30 seconds 48.5 kVA
Input voltage, maximum 96 Vdc
Output voltage 75 Vac
Output current, 30 seconds 621 A
Output frequency 1544 Hz
Power Loss
At full load (48.5 kW) 1986 watts
Efficiency at (48.5 kW) 96
Cooling
Air cooled - forced air cooling provided by thermostatically
controlled blower.
Weight 22.6 kg (50 lbs)
Control Method
Shaft position sensor for phase and frequency control.
Field Current control of counter emf.
Power of blower (100 watt max.) is included in motor and controller
losses.
C 1
139
01
TRANSAXLE
DESIGN CONCEPT A6
TYPE: 3-speed with electronically controlled gear changing mechanism'v
Fifi i l drive gear
Ratio 7.2666Bearing type ball bearingMaximum torque input 418 Nm (308 lb-ft)
Maximum torque output 3042 Nm 2244 lb-ft)
Weight 17.7 kg lbs)
Axle
Axle weight 9.0 kg (20 lbs)
Transmission
i
Gear ratios 1, 1.74, 3.86
Bearing type ball bearing
Maximum torque input 109 NmMaximum Torque output 418 NmMaximum speed input
2004 mWeight kg lbs)
Gear shift mechanism
Electronically controlled 2.2 kg (5 lbs)Weight
Transaxle Drive Line Efficiency
@ 6614 W input 92.77
@ 22520 W input 95.35
@ 57112 W input 96.74
Weight of Complete Transaxle 49.4 kg (109 lbs)
140
1
r
r
K
BATTERIES
TYPE: Lead-acid (nickel-zinc)
Battery characteristics
Specific energySpecific powerCycle life (80% discharge)
CostEfficiency
Total installed battery weight (lead-acid)
40 (80) Wh/kg100 (150) W/kg800 (500)50 (75) $/kWh60 (70)
556 kg (1226 lbs)
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141
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A.C. TRACTION MOTOR
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AUTOMATIC 5H/FT UN/T
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APPENDIX Q
ADVANCED ELECTRIC VEHICLE PROPULSION SYSTEM
DESIGN CONCEPT: D2
GENERAL DESCRIPTION:
Propulsion system using an advanced design do motor with electronic
commutation which functions as chopper for voltage cone' l and voltageboost for regenerative braking. Extra power for accele.- :ion and brakingis provided by a flywheel using a continuously variable transmission.
155
1474 kg (3250 lbs)544 kg (1199 lbs)
205 kg (452 lbs)
26 kW5400 rpm7800 rpm90.4/
96 Vdc
43 kg (95 lbs)
2.44 MJ (678 Wh)46300 rpm
16 kg (35.3 lbs)
34 kW46300/15400 rpm
94%
71 kg (157 lbs)
36 kW
23200 rpm9 kg (20 lbs)
50 kg (109 lbs)
29 kW16 kg (34.8 lbs)
40 Wh/kg (18 Wh/lb)100 W/kg (45 W/lb)
60%
223.7 km (139 mi)
160.9 km (100 mi)
15 sec
GENERAL PROPULSION SYSTEM DESCRIPTION
DESIGN CONCEPT D2
N'
Curb weight
Battery weight
Propulsion system weight without battery
Traction Motor
'Electronically commutated brushless doRated powerBase speed
Maximum speedEfficiencyVoltageWeight
Fiber-Composite Flywheel
Total stored energyMaximum speed
Total weight
CVT
Planetary cone type
Maximum powerMaximum/minimum speed inputFull load efficiencyWeight
Magnetic Coupling
Maximum powerBase speedWeight
Transaxle - 3-Speed
Weight
Controller
9-phase chopper
Rated powerWeight
Battery - Lead-Acid
Specific energy
Specific powerEfficiency
Propulsion System Performance
Range for steady 45 mph cruiseRange for SAE J227a Schedule D
Acceleration 0 to 55 mph
156
i
61
TRACTION MOTOR
DESIGN CONCEPT D2
TYPE: Electronically commutated brushless dc, four pole design withfield excitation provided through slip rings.
Rating
Power continuous 26,000 WattsBase speed 5,400 rpmMaximum speed 7,800 rpmEfficiency 90.4%Voltage 96 VdcCurrent 300 Adc
Number of phases of armature 9
Dimensions mm in
Armature stack length 85.7 3.375slot depth 22.9 .90slot width 6.4 .25
Rotor diameter 138.7 5.46Rotor length 85.7 3.375
Air gap diameter 138.9 5.469Housing I:D, 220.7 8.69Housing O.D. 246.1 9.69Housing length 292.1 11.5Bearing O.D. 88.9 3.5Drive shaft O.D, 38.1 1.5
Weights kg lbs
Armature iron 10.66 23.5Armature copper 10.43 23.
Field copper 4.99 11.
Rotor iron 8.39 18.5
Shaft 2.49 5.5
Housing 2.72 6.
End bells 2.49 5.5
Miscellaneous 1.04 2.3
Total unit weight 43.21 95.3
157 #I
i
Traction MotorPage Two
Resistance
Armature winding .1098 nField winding 204.1323 P
Winding description
Armature Lap winding - 36 Slots
Field Wound rotor, supplied by slip rings
Losses at continuous power (26,000 W)
Total 2761 WOhmic 1849 WHysteresis 138 WEddy current 221 WBearing friction 359 WWindage 193 W
Cooling
Air cooling provided by thermostatically controlled blower
Cost, weight and power of blower is included in motor/controllercost, weight and losses.
CONTROLLER FOR ELECTRONICALLY COMMUTATED DC MOTOR
DESIGN CONCEPT D2
TYPE: Variable voltage, 9-phase electronic commutation with chopperfield and armature control.
N"
Ratings
kVA rating, continuousInput voltageOutput voltageOutput current, maximum continuous
Power Loss
At full oadEfficiency at full load
Cooling
*Forced air- cooling
Field Control
Maximum currentMaximum voltage
Weight
29 kW96 V96 V
350 Adc
1180 W96.1%
1.34 Adc96. Vdc
15.79 kg (34.8 lbs)
Control Method
Shaft position sensor for commutationArmature current chopper below base speedField current chopper above base speed
*Cost, weight and power of blower is included in motor/controller cost,weight and losses.
< .
1591
FLYWHEEL
DESIGN CONCEPT D2
TYPE: Bi-annulate rim fiber-composite
Maximum speed
Maximum stored energy
Available energy for a 3:1 speed range
Specific energy
Flywheel dimensions
Inner ring, S-2 glass/epoxyI.D.O.D.
Outer ring, Kevlar 49/epoxyI.D.O.D.
Height
Hub - aluminum with kevlar reinforcement
Kevlar O.D.I.D.
Aluminum hub I.D.r
f Weights
RingsSpokes
E HubBalancing weightsTotal
Housing
Total
Vacuum
Bearings
Seals - hermetically sealed
46316 rpm
2.44 MJ (679 Wh)
2.17 MJ (603 Wh)
64.3 Wh/kg (29.18 Wh/lb)
mm in
253.7 9.99
303. 11.93
303. 11.93
362. 14.26
98.6 3.88
146.1 5.75121.7 4.79111.5 4.39
kg lbs
8.4 18.52.47 1.03
1.60 3.53.09 .19
10.56 23.27
5.44 12.
16.00 35.27
Ball bearings
F
160
CONTINUOUSLY VARIABLE TRANSMISSION (CVT)
DESIGN CONCEPT D2
TYPE: Planetary cone type with magnetic coupling for peak torquelimiting and declutching capability.
H
Rating
Maximum powerMaximum/minimum speed inputMaximum/minimum speed outputFull load efficiency @ (33,302 W)Ratio
Torque
(0 to 55 mph in 15 seconds)Maximum input @ 21,007 rpmMaximum output @ 4,333 rpm
Loss coefficients
Viscous dragSpin torqueCreep
Bearing types
Weight including magnetic coupling
34,000 W46,316-15,439 rpm
7,800-1,158 rpm94%12:1
16.12 Nm73.39 Nm
2%4%3
Ball bearing
80.5 kg (177.5 lbs)
161
0
TRANSAXLE
DESIGN CONCEPT D2
TYPE: 3-speed with electronically controlled gear changing mechanism
Differential
RatioBearing type
Maximum torque inputMaximum torque outputWeight
Axle
Axle Weight
Transmission
Gear ratiosBearing type
Synchromesh type
Maximum torque inputMaximum torque output
Maximum speed inputWeight
Gear shift mechanism
Weight
Weight of Complete Transaxle
5.444Ball bearing
460 Nm (340 lb-ft)
2508 Nm (1850 lb-ft)17.7 kg (39 lbs)
9.1 kg (20 lbs)
1, 1.74, 3.86
Ball bearing
119 Nm (88 lb-ft)460 Nm (340 lb-ft)9000 rpm
20.4 kg (45 lbs)
2.2 kg (5 lbs)
49.4 kg (109 lbs)
f 1
162
1
BATTERIES
DESIGN CONCEPT D2
TYPE: Lead-acid (nickel-zinc)
Battery characteristics
Specific energySpecific power
Cycle life (80% discharge)CostEfficiency
Total installed battery weight (lead-acid)
40 (80) Wh/kg100 (150) W/kg800 (500)
50 (75) $/kWh60 (70) %
544 kg (1199 lbs)
E
1630
165
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INPUT RATINGS: ^1
MAXIMUM RPM-6000
MAXIMUM H. P- 67
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CONTROLLER
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APPENDIX C
MODELS FOR PROPULSION SYSTEM COMPONENTS
A brief description of the models for the battery, transaxle, motorand controller follows. A typical page of computer printout showing thatportion of the computation of the power and losses at each time step isgiven in Table Cl.
175
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179 6
Battery Model
For a vehicle in normal operation the power level fluctuates from thehigh values for acceleration to much lower values for steady driving. Withthe fluctuating power of stop and go driving the range of an electricvehicle will be substantially less than for constant speed driving on alevel road. Part of this difference is due to the fact that the availableenergy from the battery when operated at high power is less than thatavailable at low power. (Ref. 19)
The available energy from a battery is dependent upon the mannerand rate of discharge. A steady discharge at low power extracts moreenergy than a steady discharge at high power. Figure Cl shows thevariation in available energy from an ISOA lead-acid battery for varioussteady power levels, with energy and power normalized to the values perpound of battery. For a variable rate of discharge the total availableenergy may be estimated by a variety of ways with differing degrees ofaccuracy. (Ref. 33, 34)
One scheme used an accumulation of increments of fractional dischargein which a period of high power provides a disproportionately greaterpercent of discharge than a period of low power. The extent of thedisproportionality is calculated from the curve in Figure Cl. Some otherschemes use models that attempt to relate to the physical characteristicsof the battery using a few well-chosen parameters. Still other schemesinvolve using the average power over the driving cycle to compute theavailable energy. A root mean square (RMS) average and a simple arith-metic average have been used.
In an earlier study on the benefits of regenerative braking, (Ref. 30)it was found that the difference in available energy using the differentmethods of calculation was small and that the available data on batteryperformance with fluctuating power levels did not provide a strong supportfor any one calculational method. The method using RMS averaging appearsto give the lowest range and, therefore, was considered to give an appro-priately conservative value of power to use in range calculations.
The battery energy vs. power curve of Figure Cl was representedby a mathmatical equation which was incorporated into the subroutineused to calculate specific energy as a function of specific power. Twosuch equations were used; one for ISOA lead-acid and one for Ni/Zn.
180
10 20 40 60
Specific Energy Wh/kg
Figure Cl. Ragone Chart for ISOA Lead-Acid Battery
181
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4
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For the ISOA lead-acid the relationship is as follows:
*E = 23.543 - .81 x P + .784 x 10 * P 2
Where
E = specific energy Wh/lb
P = specific power W/lb
The relationship for Mi /Zn is as follows: (for positive values of P)
**E = 20.4 +64.3 - p
1544
Unless P is greater than 64.3, in which case E is set to 21.8.
Trans/axle Model
The subroutines for the propulsion system include the calculationof energy losses in the transmission and axle gearing and the calculationof the speed and torque multiplication associated with the various gearratios. Loss coefficients and gear ratios are input to the program fromdata cards. The tire rolling radius is also an input value. From thevehicle velocity and tire radius the axle speed is calculated.
RPM =Vx60x12A 21TR
The pinion gear speed is then calculated from the axle speed by multi-plying by the axle ratio.
RPM Pinion=
Ratio x RPM Axle
And the motor speed is calculated from the final drive pinion bymultiplying by the appropriate transmission ratio, which is selected tosatisfy the shift point criteria which in turn is based on the vehiclespeed and power requirement.
RPM= RPM Pinionx
Transmission Ratio
*Numerical fit of curve provided by NASA Lewis.*Numerical fit of curve (ref. 19, p. 200).
182 61
The final drive pinion power is found by adding to the drive axle
power an increment of power due to an increment of pinion torque found
from the following:
AT = a0 + a 1
RPM Pinion + a2TPinion
Where a 0 , a 1 and a 2 are loss coefficients from data cards.
The increment of power AP is found from:
AP = AT x RPM Pinionx
27r
The losses in the transmission are added to the final drive pinionpower to obtain the motor power. The increment of frictional torque forthe transmission is found from the following:
T =l(1 + RPM ) x (B + B x RPM + B x Torque)
T 2 RPM 0 1 2
Where B02 B 1 and B2 are read from input cards.
Torque is the motor torque for a frictionless transmission
RPM is the motor speed
RPM Pinionis the final drive pinion speed.
The increment of power loss associated with the increment of torque
is added to obtain the motor power.
Motor Model s
Two motor models were used to represent the two types of motors. Thedo motor is modeled in terms of the known torque/current and speed/voltage
relationships for a separately excited do motor. The three-phase inductionmotor is modeled in terms of its equivalent circuit. The calculated
losses for each motor type included the following:
WindageBearing Friction
Eddy currentHysteresis
Copper I2R
183 I
Model for DC Motor
For the do motor the torque andthe air-gap flux in addition to theThe air-gap flux at the design poin,start to saturate the iron and thatcurrent as shown in Figure C2. Thefollowing equation:
generated voltage are dependent uponarmature current and rotor speed.t is assumed to be high enough to justflux would be a function of fieldcurve can be represented by the
*Flux = 5.7 tanh (.18226 * x) + .1033 * x + .5
Where x is a non-dimensional ampere turns of the field coils and Fluxis the non-dimensional air-gap flux. At the design point x = 6 and Flux= 5.67. The flux can be raised or lowered by changing the field current;but since saturation effects limit the amount of flux that can be obtained,the field current is limited to values below some reasonable overloadcurrent.
The required flux and armature current of the motor is found fromthe required generated counter emf and motor torque by iteration. First
the flux is found from the relationship that the counter emf is propor-tional to the product of the speed and flux and that the required counteremf is the terminal voltage minus the IR drop of the armature. Thus
Flux = Kl (E - IR) /rpm
Where K1 is a proportionality constant dependent upon the motor design
E = terminal voltageI = armature current (trial value used)R = armature resistance
RPM = rotor speed
Then the armature current is found using the relationship that rotortorque is proportional to product of flux and current. Thus
I = K2 * Torque/Flux
The range through which the Flux may change is limited by themagnetic properties of the iron and the limiting current of the fieldcoils. At low speeds where excessive flux would be required to producethe counter emf, the method of avoiding excessive field current is toreduce the effective motor terminal voltage by using the armature currentcontroller.
The eddy current losses are calculated from the air-gap flux and motorspeed using the following relationship: (Ref. 3)
APeC = K3 (RPM * Flux)2
*Numerical fit of curve from Ref. 15, p. 123.
184
t
0 5 10 15 20 25 30 35
Dimensionless Ampere-Turns
Figure C2. Air-Gap Flux vs. Field Current
185
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APHyst = K4 RPM (Flux)1.6
The bearing losses are taken as increasing linearly with speed andthe windage losses as quadratic with speed.
The copper 12 losses are simply the sum of the field I 2R loss and thearmature 1 2 R. Field currents and armature currents are both calculatedto satisfy the flux and torque relationships.
Three-Phase Induction Motor
The model for the induction motor is based on the equivalent circuitshown in Figure C3 for a single leg. One third of the power is developedin each leg of a three-phase motor. The motor is assumed to be deltaconnected so that full-line voltage is applied to each leg. The circuitconstants Rl, R2, R^, X1, Xp and X3 are calculated in the subroutine fromthe input charaicteristics of the motor. The input characteristics arethe efficiency, power factor and percent slip at rated power and speedand distribution of losses. At speeds less than the base speed theterminal voltage is reduced to be a linear function of input frequencyand at speeds above base speed this voltage is set at a constant value.
The currents in the various elements in the equivalent circuit arecalculated by first assuming a value of E 2 from which preliminary valuesof I 2 , I 3 and I 4 are calculated as follows:
I 2 = E2/Z2
I3 = E2/Z3
I 4 = E2/Z4
Where
Z2= R 2
+j X2
Z3 = .j X3
Z4=R3
Summing these preliminary values of current gives the I 1 vector} 4-I 1 = I2 + I3 +I4
Using this value of I, and the assumed value of E2 a new value of the
E1 vector is calculated by vector addition.
186
N
V)ri
N
T
N H N !n N N N N N H S."b 10 b t0 b b RS r0 rti t0 Ot t s .= t t t t .0 .0 +•^tl d d d O. d d d d O. O¢ 4 4 a C: a C: C
O•r4JUO'CCr-i
a)U 4-C Ob
4J 4-)C •r O
L a) U a) S-L C U rrt3 C a) u
U +^ +.► t0 U
UQ) a) to r0 r-- - P a)•r U a) n7 S_ a) U r-
c •^s•
a)4J r0 a) ai >a C +J U +J O O 0) a) S- r
SO-b a) W WN a) ^ M M C74J S- S.• N •r t0 .Y C Wr O S- II a to to a r0 •rO U O S_ aJ N r a) N> U M S- O r- •r
S- P-.t S• .- S. i-) Ma O S• O S- O S- a) UG N iJ O + 4J O C 4J O C
•r t0 (0 +J t0 4J O 0 +J C) (vr .0 +J O wt 4J O S. +-) O (0 L(n G. V) w H V) 1-1 (/) O
II II II 11 11 11 11 II 11 11 11•rLL
r r- N M r N M t- N MN LLJ 6-4 f.r I" = w = X X X
a 1
I
18/
Elm = E2 + I
1 Z1
Where
Z1 = R1 + j X1
This value of E 1 will differ slightly from E due to the error in
assumed value of E 2 . The value of E2 and the cu 4ent vectors are readjustedby the ratio of the correct value of E 1 to the calculated value E1Areiteration confirms that the correct value of E 2 and the current Vectorsare obtained.
The windage, bearing friction, hysteresis and eddy current losses arecalculated for the induction motor in the same way as they are for thedo motor. The air-gap flux is calculated as that required to producethe necessary counter emf at the operating speed using the followingrelationship
Flux = K1 E2 /RPM S
Where K1 is a proportionality constant
E2 = counter emf
RPM s = synchronous speed
The counter emf E and the currents in each of the elements of theequivalent circuit ar found by iteration by starting from a guessed atvalue of slip. The starting value is based on a linearization of theSUP torque curve using
Slipx = Slip * Tor/Torrt
Where
Slipx = trial slipSlip = rated slipTor = motor torqueTorrt = rated motor torque
The trial slip is substituted into the equations for the circuitand the values of current vectors are solved after the reactances are _.adjusted for the input frequency. The power output of the motor with thetrial slip is compared with the desired power and the slip is readjustedto raise or lower the power output as required.
The iteration process converges rapidly to the required slip andtorque if the torque is less than the breakaway torque of the motor. Thebreakaway torque and slip are also calculated; and if the repaired torqueexceeds this maximum torque, this factor is printed out.
188
I
Control l er Model
The subroutines for the various types of motors calculate the con-troller losses as a function of the idealized battery current usingthree input parameters used as loss coefficients to characterize the con-troller. The power loss is in the following form:
AP = C C + C1I + C2I2
Where CO , C 1 and C 2 are input values
I = idealized battery current.
The idealized battery current is simply the average current requiredto satisfy the power and losses of the motor using a lossless controller.
The loss coefficients C S C and C are separately calculated from thenature of the controllers an ld its e^ements.
At the rated power condition with a certain input current, there willbe RMS currents through diodes, and SCRs or transistors. For a specificdistribution of current there will be an identifiable distribution of losses.
The losses in the diodes and SCRs are principally due to their forwardvoltage drop and this value influences the coefficient C in proportion to
the diode current fraction. The rate of change in the voltage drop in-fluences CAn additional loss for the diodes and SCRs is due to theirreverse le idkage current times their reverse voltage. The losses in tran-sistors are due mainly to the collector-emitter sat:!ration voltage, thebase-emitter saturation voltage and to the collector-emitter leakage current.
Using catalog values of voltage and leakage currents for probablediodes and transistor types and numbers of units in series and parallelestimates of the loss coefficients were made. These result in overallefficiencies of the controller from about 93 to 96 percent with the higherefficiencies at higher loads.
The model does not take into account the different modes of operationof the controllers. When the motors are above their base speeds the effectivevoltage at their terminals are the maximum value. When the motors arebelow their base speeds the effective voltage is reduced by use of a currentchopper. The switching losses of the chopper will increase as the effectivevoltage is decreased. A more sophisticated model would account for thevariations in switching losses, perhaps by readjusting the loss coefficientsas a function of the effective voltage.
In addition to the switching losses in the semiconductor switches,there will be differences in the distribution of current in the circuit
elements and changes in the current waveforms as the chopping frequenciesand on-off ratios change. The waveforms and distribution of current in thetransactions and diodes were calculated for several load conditions for theinduction motor operated above the base speed. The current (RMS) throughthe free-wheel diodes is approximately equal to the out-of-phase componentof current and the current through the transistors is approximately equal
189
to the vector sum of the in-phase and out-of-phase current. These valuesWere used for estimating the loss coefficients.
For a more sophisticated model, the current distribution and waveformsduring chopper operation should be calculated, and used for estimatinglosses.
190
61
APPENDIX D
GUIDELINES AND BACK-UP INFORMATION FOR COST CALCULATIONS
4 ,
191 II
Guidelines for Life Cycle Cost Calculations
* Costs shall be calculated only for the propulsion system plus thebattery, therefore other vehicle costs, insurance, taxes, etc. arenot included.
* Use 1976 dollars
* Acquisition cost is the sum of the OEM cost (manufacturing costplus corporate level costs such as general and administrative,required return on investments of facilities and tooling, cost ofsales,...) of components plus the cost of assembling the componentsplus the dealer markup (assume 17%).
* Annual production is 100,000 units
Operating cost is the sum of maintenance costs plus repair costsplus electricity cost plus battery replacement costs.
* Electricity cost is 4 cents/loth from the wall plug.
* Vehicle lifetime is 10 years and 100,000 miles.
* A constant non-inflating dollar should be assumed. No inflationfactor is included in the discount rate since it is assumed thatpersonal disposable income tracks inflation. A 2% discount rate forpersonal cars shall be used as it represents only time preference(opportunity cost).
* Cost of finance is not included in this procedure since it isassumed that the discounted present value of the sequence of totalpayments would approximately equal the original purchase price.
* All expenses are assumed to be costed at the end of each year.Year "Zero" is reserved -for those costs which must be incurredbefore the vehicle is operated.
* Assume chassis (propulsion system) salvage value is 2% of thepurchase price, depleted battery salvage value is 10% of the purchaseprice, and used battery salvage is 50% of the purchase price pro-ratedover the remaining life of the battery.
* In determining battery life assume the vehicle is driven 10,000miles per year. For convenience in calculation assume the mileageis accumulated through successive SAE J227a Schedule D driving cyclesfrom 400 - 10 mile trips per year, 150 - 30 mile trips, and 30 50 miletrips, charging after each trip. The battery cycle life shall bedetermined based on these trip profiles, field environmental effects,and the degradation due to the actual conditions imposed on thebattery by the propulsion system and vehicle.
192
The calculation of life cycle.cost shall follow the format shown onWorksheets 1 and 2 using the following instructions.
1) The purchase price is entered on the appropriate lineof the life cycle cost worksheet as a year "Zero" cost.
2) Operating costs: electricity, maintenance and repair,and battery replacement costs are copied from the operatingcost worksheet to the same position on the life cycle costworksheet.
3) Discount factor - 1/(1 + i) t is computed for each year(where t = year 0 to 10 and i equals the discount rate).
4) For each year, the discount factor times the cost givesthe present value of the cost for that year. These aresunrned to provide the discounted present value of the lifecycle cost.
5) The value computed in step 4 is divided by the totalmiles driven to provide the life cycle cost per mile and isexpressed in cents per mile.
Y
S 1
193
01
M
Ta bl a Dl
Operating/Life Cycle Cost Analysisof AEVA Propulsion System
Concept: A6 - AC Induction Motor with Flywheel Buffer
Battery Weight: 1226 lbs lead-acid
Energy used over -"D" Cycle 212 Wh/mile
Battery Characteristics: As listed in Table 4
Vehicle Life: 10 years
Distance driven annually: 16100 km (10000 mi)
Energy cost from wallplug: .04 $/kWh
Salvage Value
Chassis 2% of purchaseBattery 10% of purchase if depleted
50% of purchase prorated over remainingbattery life
Battery Cost = ($/kWh x Battery Weight x Specific Energy/2204)
$1112
Energy Cost = Energy Consumed/mile x Miles x Price/kWh/Battery Efficiency
$141/yr
f
194
1
Weight(lbs)
59
90
65
50
35
43
50
392
1226
1631
Cost
118
189
464
354
210
107
100
1542
60
1112
2714
Unit Price Unit
Axle 2. $/lb
Drive Motor 2.1 $/lb
*Controllers:
Battery to Motor 7.38 $/kVA
Generator to Motor 7.38 k/kVA
Flywheel 6. $/lb
Motor/Generator 2.5 $/lb
Transmission 2. $/lb
Subtotal:
Assembly and Test:
Two manhours at $30 per hour
Batteries
Total: r
Acquisition Cost = Total + 17% Dealer Markup= $3175
Ta bl a D2
Propulsion System Acquisition Cost AnalysisConcept A6 with Lead-Acid Batteries
*Controllers are rated at 63 and 48 kVA each.
t
195
Table D3
Worksheet 1Operating Cost Worksheet
Concept A6 with Lead-Acid Batteries
YEAR1 2 3 4 5 6 7 8 9 10
Mile Dependent Costs
Maintenancefi
Electric .10 .10 .35 .10 .10 .35 .10 .10 .35 .10
Mechanical .10 .10 .30 .10 .10 .30 .10 .10 .30 .10
J Energy Buffer .10 .10 .10 .10 .10 .10 .10 .10 .10 .10
TOTAL .30 .30 .75 .30 .30 .75 .30 .30 .75 .30Wa
RepairW
Electricz
FlywheelV)
( °t
Transmission .5
1. .5 1.D TOTAL
t
!Electricity
E TOTAL 1.41 1.41 1.41 1.41 1.4 1 1.41 1.41 1.41 1.41 1.41
F TOTALS A+D+E 1.71 1.71 2.16 2.71 2.21 2.16 1.711 2.71 2.16 1.71
G Mileage Each Year 10000 10000
H TOTAL DOLLARSF/100 x G 171 171 216 271 221 216 171 271 216 171
Battery Replacement 1112
YEAR TOTALS $ 1171 171 216 271 221 1328 171 271 216 171
I
Total Operating Cost =1 3207
Operating Cost Per Milecents/mile
.196
4)Q) Ctt CN 4.;G >
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a.
Table D5
Operating/Life Cycle Cost Analysisof AEVA Propulsion System
Concept: D2 - Brushless do Motor with CVT
iFlywheel Buffer
Battery Weight: 1199 lbs lead-acid
Energy used over "D" Cycle: 210.45 Wh/mi
Battery Characteristics: As listed in Table 4
Vehicle Life: 10 years
Miles driven annually: 16,100 km (10,000 mi)
Energy cost from wall plug: .04 $/kWh
Salvage Value
Chassis: 2% of purchaseBattery: 10% of purchase if depleted
50% of purchase prorated overremaining battery life
Battery Cost = ($/kWh x Battery Weight x Specific Energy/2204)
= $1088
Fnergy Cost = Energy Consumed/mile x Miles x Price/kWh/BatteryEfficiency
= $140/yr
F I
0t
Table D6
Propulsion System Acquisition Cost Analysis
Concept D2 with Lead -Acid Batteries
Unit Price Unit Weight Cost
O bs.) ^$)
Axle 2 $/1 b 59 118
Dive Motor 2.3 $/1 b 95 219
Controller 7.37 $/kVA 35 214
Flywheel 6 $/lb 35 210
*CVT $/lb 178 661
Transmission 2 $/lb 50 100
Subtotal: 452 1522
Assembly and Test:
Two manhours @ $30 per hour 60
Batteries 1088
Total: 2670
Acquisition Cost = Total + 17% Dealer Markup = 3123
*Includes magnetic coupling and hydraulic pum p motor.
r,
Ta bl a D7
Worksheet 1Operating Cost Worksheet
YEAR
i
Mile Dependent Costs
Maintenance
Mechanical
Energy Buffer
k^ A TOTAL
ic-
Repair
Electric
Differential
Hydraulic Pump
D TOTAL
Electricity
E TOTAL
F TOTALS A+D+E
G MILAGE EACH YEAR
'! TOTAL DOLLARS(F/100) x G
Battery Replacement
1 2 3 4 5 6 7 R 9 10
.62 1 .82 .87 .82 1 .62 1.07 .62 1 .82 .87 1 .82
.10 .10 .10 .10 .10 .10 .10 .10 .10 .10
.72 .92 .97 .98 .72 1.17 .72 .92 .97 .92
•5 .5
.6 .6
.1 .1 .l
.1 .5 .6 .1 - .5 .1 .6
1.4 1.4 1.4 1.4 1 .4 1.4 1 .4 1.4 1.4 1.4
2.12 2.32 2.47 2.82 2.72 2.67 2.12 2.82 2.47 2.38
10000 10000 10000 10000 110000 10000 10000 10000 10000 10000
212 232 247 282 272 267 212 282 247 238
1088
212 232 24'1 282 272 1355 212 282 247 238YEAR TOTALS $
k
c I
Total Operating Cost $3207 Operating Cost Per Mile 3.207
(cents/mile)
!I200
01r•PE4JCOU
E-Iuuo!)
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o(O4JO
>Or
C0) O)4- •^O S..
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r r lVCC
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co
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r 1 r
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O N N d' rch el' 00 N tG
r r N Ol N
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(O N N CC cor ^• 1^ r 01 Or N N
OO N N NrM r
Mr r
M
CJU OJi >) 41 4.3 r N r-- N rd 4-•) •O U C it b : (CS
•P G C QJ Ln C N CG1 U RI CO E= 4-34-3N .,- C >0 4J N E >> Mz ^ C +^ ^to S- S- N S-U •P v S.. %0 0 Si C 00.0 {.-) •P 4-3 4) O N a J O O OU U (a C •1••) r (n Q) 4-) aJ Q 1 U 4J N Xi O Cl •r • -) C. CO 01 4-) O f— N U 4)O r 4) to to N t ra to (0 O r •P r0 i P^CL W w co I= U > co > F- D Li CL v
r N M P7 LO LO r• co. 01
201
Table D9
OPERATING/LIFE CYCLE COST ANALYSISOF AEVA PROPULSIONS SYSTEM WITH NICKEL-ZINC BATTERIES
Concept/A6--Ac induction motor with flywheel buffer.
UNIT WEIGfi i
(lbs.)
Axle 59
Drive Mount 63
Controllers
BM 45
GM 35
Flywheel 35
Motor Generator 30
Transmission 50
Subtotal 317
Assembly and Test
Subtotal
Batteries (Mi-Zn) 490
TOTAL 807
Acquisition Cost (17% Markup)
Energy Cost: 102 Wh/km (165 Wh/mi)
Assuming same repair and maintenance cost as in lead acid case:
CANDIDATE LEAD ACID
(A6) (A6)
Acquisition Cost 3175
Annualized Acquisition Cost 317.5
Discounted Annual Cost @ 2% Discount Rate
Electricity 126.6Repair and Maintenance 61.5Battery Replacement 99.8Drive Train Salvage -3.7Battery Salvage -26.6
Discounted Annual Operating Costs 257.6
Present Value Life Cycle, $/Yr 575
Present Value Life Cycle, $/km ($/mi) .0357 (.0575)
202
COST
($)
118
131
333
256
210
75
100
1223
60
1283
1334
2617
3062
94
Mi-Zn
(A6)
3062
306.2
94.061.5
239.6-3.5
-33.5
358.1
664.3
.0413 (.0664)
II
-•ry --; "I
APPENDIX E
COMPUTER FLOW CHART AND PROGRAM
203
FLYWHEEL/BATTERY HYBRID CANDIDATE SUBROUTINE FLOW CHART
TRANSFERED VARIA3LES - START
1. VEHICLE SPEED2. ROAD POWER.7. VEHICLE WEIGHT4. ACCELERATION MANCNS. BATTERY VOLTAGE IF FIRST TIRE
YES
iN ROUTINE
NO
INITIAL VALUESYIMEEL SPEED AND
CALGTA ATE
LIET
AS FOR MOTORSNT
MOTOR SPEED D GEAR RATIOS
CALCULATE MOTORCALCULATE PERFORX-kNCE TABLELGENERATOR SPEED
GEAR L BEARING LOSSES
PRINT TABLE
POSITIVE CHECKVEHICLE ACCELERATION
RATE
ZERO OR NEGATIVE
POSITIVE CHECK NEGATIVEPOWER OUTPUTREQUIREMENT
CALCULATE FLYWHEEL -POWER FOR ACCELERATION ZERO CALCULATE REGENERATIVE
BRAKING RECOVERY
CALCULATE QU I PEWN
RECHARGE REQUIP^}£KT^r
CALCULATE MOTORENERGY RETURN TOPOWER FOR REMAINDER
FLYWHEEL
CALCULATE GENERATORPOWER INPUT FOR
CALCULATE GENERATOR RECHARGE
POWER REQUIRED FOk CALCULATE GENERATOR
TRANSFER OF FLriMEELPOWER FOR TRANSFER
POWER TO OUTPUT SHAFTCALCULATE
MOTOR POWERFOR RECHARGE CALCULATE MOTOR
POWER
1y
TES
REDUCE VOLTAGE VIACHOPPER CIRCUIT TDMAXI1t1M COUNTER EMFOF THE SLOWEST UNIT
[ALUAAIt MOTO
RAND
GENERATOR LOSSES
CALCULATE DITHERELECTRICAL LOSSES
IS MOTOROR GENERATOR SPEEDLESS 7HA4 THE BASE
SPEED
NO
SET FULL VOLTAGE
CALCULATE NEWFLYWHEEL SPEEDFROM DELTA K.E.
CALCULATE BATTERYDRAIN CURRENT
RETURN
G
204
f
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(;10 ^,-iNT1'JUE
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_ 4k I T F ( 16, 114) f X I114 Ff:KmA1' 11 11 ,1X,16 A5 )
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_ WfITC(161223) F;V,EI3ARM,P_BARM,WB, COST B,EFFDRk.AO(4, 11) FSL= ,WFs XFSM,RLJN),COSTFWRFfE(15,225) FSE,WF,XFSM,RUND,COSTFREAD(4,1l) 3RPR,3SPD1,SSPD27GOLDeGRVT 9 GCUR, EIAR,EFFOG41-tITF(16,227) GRPR,GS :)DI,3SP)2 9-30L),GRVT' 9 GCUR,G BAR, EFFOG-RFAD(4,11 ) GFi12,GIIYSTI,GEt)I,G[3RI,GWNDI,GFREQ,CDSTGWRITE (16, 229) GRT 2 , 341 'STI , GEDI ,GBIRI,GWNDI, GFREQ, COSTG
205
--f XKF^ 5EJ-f '(WK7i-v ' fx A* V-79-7 9W-0v-T—xkrt-T 'TA2 —,wTTff;'TTu —cSTWR I TE_( - i5 ► 2311 TX 41 ,',l v T XMR2 9 TX MR3 t TXAU i TX Al t T X A2 v W TX 4 # TXC OST
11 FDRMAT( 81 It.). 3)11 1 F (*iR,',IikT ( 7 X 1 6 (114.4)205 F0RMt,1*(/24H VEIIICL1*(,HAkACTFRlSTICS
-- - 14X P 12FB4,S'v4EI3-I ,r g4xti!-im4x.pdvLnA3y4ij_9 Tj^_qST L0AD qlXv17HWT * PROPAG2ATI(I'll I - a t 1X t 12FIAII', DRAG CDA 9 3X 9 11HA IP% DENSITY? lXq 14HROTeINER.FACTo3/7315.5)
ZU7 FCRA AT (1Y 411 TIR F FiILC T7k S /5X9lllRADI US I NCI i 12X P 27HROLLING RESIST.2 CUE F Fl (' I 1: %Il S t 4 X 9 e?l HS H I FT 1) 0 14 T S IF I / S FC / lG 15. 39 3E 15. 5 1 3F 15 9 2 1
209 r-'0K44T(/141 AXLF f'4CTORS /7X 15HRAT 10 9 9X v 6HW El GHT i 8Xt I IHTORQUE CA1 P e,xt 4HCD STt 2X9 l?f iL-j SS 'Z D FF'. 4 09 13X i 21 J A 1 , 13XP 2.4 A2/ IG1 5 .5 9
211 JkIVE 'AUTf.lk FACTORS 15xv!IHRATED PnwER94X,9H-4IN EPEE1.0 9 5x ? )111"X PERZENTOX011RATED VOLTS91X913HRA2 Tt: 1) C J!-'lN'I'7 NlT v 1X 0 5 H^ PFr tFIC qF IGHT , 2X 9 10HEFFIC I ENCYisr, 15. 15 )
2' Ftik+iAT (? E li LFI.':')S DISTRIBUTION FACTOkS /3X I H:H ILI HEATING 95X 910HHY S T E tZ I'S I S 9 3 X i I ? H E D) V C J R k F N T 9 1 X t 1 411 6E A R I N G FR IC T a 9 4 X t 7 K 14 IN 3 A-G F 6 X
'1 911F RE) 4' Y , 13.X , ef -C"OS T 9 6X 9 1 2HPOWER F ACTOR/ 8G15.5 1 1Z 1 5 F:) Rl 4T / 5 J H C j'4 T D LL r- l F -t J 11 (34 TTERY T3 140TIR ' H4RAC- TE RI STI C S
14X ,1111 Hl ,,A'TC- r) PU ^i F*.f,, ^?K 13 H I H I)LJ T V OLT 4G'F 9 IX 9 14HOUTP %;T VOL T AGE i 2X 1 1 jHR2ATED Y,4X911HSPl:C,wElGHT /6(;1505 J
r r2! 7 FbRkiAr l2,<, 1 4 IAL US ,,: FF Ao) 9 1 3X t 2 HA I 1 13 X, 2HA 2 9 11 X4t-i'OST13 rc i 5 1 5 lif,;150?
_ 2 1 9 F I R li 4 r l /50I1Zl.,,NTP(*4.LFA FROM GENERATPR TO MOTOR CHARACTERISTICS./14K 1.)(74GRi 2X P 131-11'IPUT V31- TAGE t lX,14HOUTPUT VOLTAGE,2X,13HR2ATI--J -.5Y 91-if-- PI.-- QJFN(",Yi+X,IlfiSPEC,WEIGHT /6GI5.5 I
223 PD1011T(2K,141ii-oSS C,DEFr.A..)913Xt2HA1913Xt2iiA2,llX4HCOST13015 .: , IG15 * 2 )
2,-"3 r-URMAT (/24H 3ATTLRY CHAl'•ACTERISTICS1 5X, 7HV.1^ 4X I! ISP['- , F l-IF-H3Yv 5XY1 OH SPEC, POWER,4X ' IHBATT. WEIGliT21!,X,411('OF,T,7)X,101117Frl(.IFN(*Y/6Gl5,4)FORMAT (/26H FLYiJIiEFt. CFiA!',ACTEItISTlCS I12XPI.I-IS .,-'I-C.E NIE-'GY, LX, 1411f - i-YWEEL WEIsIT t 4X,9-(MAX SPEED t l xt I 8HRUNDOW
227 C ORMAT (/191-1 GFNEPATI-all F/l (,T('PS I-, J, SP'-,ED,5X,9AMAX SPEED,lX,16HOVERLOAD PER
C L N T , 3 X, I I HR A I I: D V 0 L T S K f 13 111 A F E D C LJ R REN T , I X , 15 1 S P E C I F I C WE I G H T , 4X j 1 0 - I l'- F F I -, I r- N -, Y / 9, 3 15 . 5FfiA'AAT (2f)11 LOSS ..)I STS 13UTIU1 FACTOR /3X,13HOHMIC fiEATING,5X,IOHH
CJR' ENT tlKvl4HBEARING FRICT * v4Xt7HWI11DAGEq 6X3,9Hro) j--: V,—y l i X, 4ir, G ST /7(-,-', 5.5'
231 -FJk4AT (,/2)11 T^AVSMISSIO"k - -IAP.A'- TERI STIC S23.X,l5HillGH GF, K ),,Al l0,1K,!4HSF--C.GFAR RATIO, IX914ViLJW GEAR RAT[Ot142X, 17'ILDSS DC-FF It"ll FlITS1,17X , !,2HTjkANS.WF-JGIjT f 1IX v 4HCOST/3 6 E i 5 1 2 F 15 a 2NMOT = h-[,lAR*RPR/SI'EED1*3(-J0,WTLB %4 = 14-, BN1*P' BM
k4 TCr7q = ^CGM*PCGAWGEN = 3F3AR*GRPIVGSPDI*3f30.3 SE 3 A R MCALL VFHdr
600 : L N TI N J I--k42 I TE 16, 114) IXIWR IT E 1G, 2Z3) WV,4L;Ros 9 Wcljr)lB
E. 233 Z 6Rf1AT(/16r1 VEHICLE WFIGHTS 13H TEST .*T il5:H GROSS WT1 10H Z UR 3 WT. / 11 X # 3F 1.6a 2)X M PG=)D T=lo
NFLAS =0S J mr) = j
266
^BCt4A=J.r St.I N1
SEOJT=3.
,.. _. .. S 1511=3
JF' LAS =J
ZIP 45 1=1, 15.1 . _ --- ---4" C, J N T I AI U F—
^,,^^ r 9 : ,'' 4' ^^ c^
poolIZ- 1 00)YNTS9R A 1)( 4 r 1? 1)1t, St. -^ ? ,r
4 ^ T T i 1 r, 1.16 _._I '_ .115 FOR'^AT (1X, 1 aA5 !^
~~-W R I T ( 16 136) 1) T
136 F( , RAAT(//1.k,4JN VE°III",IL SPEC) tT END OF EACH TIME STEP DEL TA 1 = , F1 .'t, 511 S F.0 1
NT S=S= XN "S~5 1= ? r ,ITS, lo
J= 1--1F:AI)14 9 16) ( V1( L+J),L=1,10)
4H IM 16916) (V1(L+J),L=1,10)15 UINTINUEIt, FORMAT( 1 l(( I X,F 7.3))
IL=MTS....^..._.III =t)NT=O
. 3 NL = N_ +1NL -O
V\1 =3 •
_. _,_C,_- LVTF2 CAL:IJL_ TTQWL l. f: OPDt', r.) I =1, NT S
NC =NC +I
L.= I I- H I/ IL) IL +1
48 =( VV -VT) /3l_A_
JFLAJ = U
li7 RA=K*3TI4'wV*A/32.2_-
RL) = J.5*R6flA*CD A' (V A**^^:=wvk (c.o`-cis=v,a+c?^;va:^;^ )
RS=r1V*SL / 100.—. RSJil=PA+~RO+RR+RS
P=k SUlt, VA
C -,_-(.f.,NVk kT TJ WATTS F-R34 FT*L1)S/SECPL) = ( 745./550. ) *PC 6.LL ASPS( EC UR i t) fIF (JFLAG.GT .4 ) GJ TD 62
IF(JFLAG-F0.1 ) Gn TO 5762 CJVTIVUF
t TIf (ND.GT.PK4AX ) PIMAX=PD
fIFf P0. LT. PBMAX) P8MAK=PD_ _IF( PJ.GT.O. ) SE I N = SE I N +PUVDT/3600.IF (PD.LT.). )SEDUT = SEOJT+Pf)*DT/36009
--- - CALL BAR(PBARtBSE,EFsAR)E . BAMP(I) = BCUR
207
[ 1"
I r- ((3C UR. L T. ( CM I) bC M I =RCUK^IF((IC.P oGT.J.) Sf31=St3l+3CUR *DT/3600•
_______-,-. I F I BCJR, LT .J ,) SB()= SFI O+C$CJR*DT/ 3600.NT=NT+1
59 VT=VV
_ wz.1 TE( 16 9 126) 1 XI,I X2 ,I X3126 FORMAT(iN 1, 1X,16A5/1X,1[A5/ IX, 16A51
WRITC(16,12J) PKMAX L PB AX_.W^ITE(169122) SEI^IV,SFnIJT4 k I T E( 1 6, 124 1 S B I, S e JWR ITE(I59130) t3CMAtbCMIWr I TF (16, 132) SJM)
A l2) FCKkIAT (IX;22H MAX ^DI10. PaWER ,Gl.4.5 9 6H WA.TTS/1 1X,2? 1 M AX BPAKI NG PGWLR = , G14.5, 6)( WATTS )W_
12'2 FJk"iAT(1 n, 22H DkIVINu F NF. RGY IN = 9G1.4.5,11H WATT -HOURS/11K922if 0 RAK ING F -NFRGY = ,G14.5,11H WATT--TOU RS )
12 Z =_FPf4AT(1X,22!•i DISCHARGF FNl FRGY = ,G1495,100 AMP-HOURS1 1X,2 2ii 2F".H AR GE =NJLK^J Y = 9G14.5110H AMP-JOURS )
) FC'k;lAT (1X, 2lH VAr LUitRENT JUT ,G14.5.5H AMPS11 X,2Zi MAX Cl1ftF X11' IN ,G14.5,5H AMPS 1
Z'C f _RMAT ( 1X9 2.3H I STA4CE IRAVELE9 = , "014.5,6i MILES 1IF(MFI_AG.EQ.U) G:1 1J 72.0
_d I TE(1(-r2550) ')T_ 25U FLR 'AI T(//'119! 1 P_• I :I ULSIDN SYSIEM CURRENT AT END OF EACH TIME srEQ I_^
- 1S EQJAL^Trj BATTERY CUk2rVT PLUS BJFFFR CURRENT. DELTA TIME
__w 2,F6.4,4j SEC) _01TE (16,]lt3lIPS+1(1)91=19NTS)
71) CONT I NIJ EdRITE(16,128) DT
12 c7 FD RMI T(/ /546( tl AT •fE^Y uU21EN T 4T EN) OF EACI TITHE STEP. DELTA T
,tit[Tf (1b, 118) ( B AMP(1) ,I=1,NTS)d K I T E( 1 iS, 2 6 J ► fD T
260 FORMAT (// 5+ H FL YvYHF FL fiJFFFR C JRRENT AT END 3F EACH TIME STEP. DE11-TA TI +1F. _ ,68.4,4 i SL"",:1
,I k[TE ( 16,118)(PA 4 P (I ),I =?., NTS)118 FC,RMAT (1X,10Fll.4) —
C SO ENEk,,Y 4N0'CALCJLATE RANGE__7) R AN G F _ + S33)))
ZANG.J 1] = .i' S UMI*)*(v o P*13. )I ((BV*(SB11))
2AAN';C = tANGE /.8 —
K PJ (i,J t'1 = R t NG4 f1/ . 8C^ LCAO LEVEL BATTERY OVER TIME OF CURRENT DRAIN.
_ TIME = q.TIME2 = J. –_
TI ME:3 = 0.z H s i = " a.RMS2- = J.,-- DO 154 J1 1,43LW(J1) = 0.
154 C(iNTIN.)E rX = RV/14B
--- J(? 15' I=19NTSTI'ME3 T1ME3+ DTIF(A(3S(BAJP( I) ).G •I'.5.) TIME = TIME + DTIF(BAdP(I).GT 5 ) TIIE2 TIM 2 + DT2M 5i = 2°•1S1 *t RAMP (i )'^'^?) j;IF`( BAAP (I) .(;T.O.) R4S2 = IMS2 + DAMP( I )*. *2PR = X"BA'IP(I)
208
Pwo = PR
I F I P d 1) . L T 9 U.
Pk,x = PR
CALL 3AR( PRX C12 6
B L k,( 1) 6 LW 1) + PR/F
r, 1, L L_ I A3LW( 1 ) .1L,: + PR/f'IL iv ( 4 ) = 3L W ( 4) 1- 11 43 / F
153 f" NT I NJ F1 11 t 4
fttfft0r, teit-IflTY OF THEBL 4 W 1) 3 LW ( J 1. 1 *^) T / 3 6(1 0.1 55 C f; N T 1 1.) E ORIGIN&T, PI'Tt"'I" 119 POOR
—1 p, 7m —s i / T I M F
M I Tr 1 , 1 211 __ 1 X."4 K I T H 16
8 1' C' k %' AT M Y ?,, I I W! t., AV17 f" AG I NG FOR PBAP170 : D N T I OF
p H ^R IV S I/I F (L . Q. 2D '' 111R= .^^1D (S B 1 +5 BO ) 1W P/T IM EI F ( L . w. 3 )—P 60 "). t- 11 VV SBI + S BO) /WR/T I ME3CALL 0A ! ' BAR , 1 LINKr: BAR 1.125-,CPAQw2 iTFl 16 1 PIAA R k
A LL B AR i P 3AR, 40 FBAR)^ -d R I TE ( 16 9 112) F'BP.Rvr- llARRlAr GLJ = kAPlGE*El3 Ak/13.FXX = ll v^(SM + sfl(3)/SJIAD,'R I T F ( .16, 1 Wd
1 4 F t M A I' ( 1 ^ I 1 .1 IT 11 k F OP ! [--P AT 10 NI T17 ( 16 9 1 00) kA'q6FL,FA,,Jr;F:r,',EXX
..? 60 F R'l..% r..( '- 31 1 RAVSE E V, I T I i L F- "', D - A-'-' I D B A T T E k Y i-v!4.5t6H MILES135 HFl RANGf- dITH NlC<E-L-ZPJC DATIEI<Y =,G 14. 5, 6H "41 L E S22 9l Ls4l-:k, Y fONSJNI-I--,,) PEE;, MILE G14-5,10H W-H/MILEp 0 K = RV oll KA '32/VqBI F L. EQe ,-) - ) PBAK= 34J3.t,(BV*SBI/vqB/Tjmr2)
P ,')Ad, = 3iJ0.'(3V*SBl/WB/TIME3)CALL
G E B A R --- 1 , 1 2 6 E. b, AWRITE( 16,112 Q-1 1^. B A KP.At,4 GEL= R'^ pvo *EB4 /J^,.CALL 6AP(PbAR,4D.,EBA( )WW'E( 16 t !!.2) 1`54REBARRANGI-N = RAN G0 *1---BAR/).3.
166 F3KMAT(221 WITHOUT REGEME'RATION1-'XX = iW*S4 I/SJ4)WRIM16 7 160) RANGELvRANGEPJ,EXXL =
L + l
IF(L.GTo3) GO TO 172
W R I TF ( 15 1 15 9 )
I F( L o E , ^' a 3 D vi R I T E 16 t 1381
1;5 " F(i t^; ,I AT 1 38 11 AV ERAGING OVER TIME OF FULL CYCLE3o To 170
172 F* 3'4 T I N UE169 FORMAT (//32H ARITHMETIC AVERAGING FOR V 'BAR /8Xv4HPBAR98Xf4lEBAR)
WRI TE ( 16 t 1 62 )162 F (J:R -11,1 T ( // 52H STE M 3Y STCR LALZULATION OF BATTERY FRACTION USED.
209
"
~ -~.^PI-0- L It
''--' -'^~~''~ '~~--'----'--'--'---------' — -----'--~
'L_^^.
r*nwVv *`»n/ » 1 L W\3v
=._~'-~___
FX u _ 3y StiKwrlTE(l5t!6%) 94N",FLvRANGE^^1XX
^ _- _w x I l^^" ----- ^KANGE- = SJMJ*°i3/:Lo(z)
101GEL - -A4NCLL/°S
_ RANGE- /°'d^---------------~---'-- --'--'--------
^ ITF^_lb' .-___-__ ------KE^6-(^ " l X
cJ , X ° ;T °-'-'-^[I.) .l) x
- ' I F . (u G|^ T 6 10ALL ;Xl 7 ..
)Jll 8TE-,[B J~
T^^-' - `
F ^^^ G^' lF^1 gJ°43°} u6 T'` ^J
^ p AR = 'o[' TO 1^3
-_--___.--_--- __-_-10 t:uAK = 2 4 °8l^X + °784E-02*0*2
. ^r Ti;^0___-' -T'] |-----
-J ° US-; - { --'---
Z0 X '-- '- - ---F`- -------------------- -
[^^^ = ' 2 ° ^ +5^^l^ ( (^4 ° ^-K ]/ ° 1544^
'---'-r] *[TJkJ
L [ JLATEs VL- HICLE WEIGHTS
- -'---
_1 t S p E[ A 19 F R EQ2PL, 8 q ,V Z 11\1,VCR li3T, B^- ICURv 9'IFRV' C8M0,CR MI. " r,8M2 ' PCGM * VC6M8NvV C6M0T
A R EFFS XF SM, RUND , GRPR
---'- - - TX'Al---
^P5 = ^^ X + UT C T ^ F ^GEN WTXM^vRjP'^ WP + ^^uS + NPA YY
R P4
C 'fFilS POUTI I ll--- GIVE CURRENI CjJT OF FLYdHEFL BUFFER A4D SU13114CTS IF FROM BATTER
-------'-
C FLY 4 H F E'-
MAXR 3UMFC 6WMFFR VA VN VT----D3vPFY,P894PD,FQvEH0,0ELFC vP@aR
^QmMON /D/IXl ,lu2 ,NT. ,NA&8E,SJMDtVC°TOTE,XMPG
210
C3HwJ\1 lC/ Y104SaW)ltY,t.'TESTiWPR013 I WAX ,WMOT,WTCBM,WTCGM,WBtWV,WFtIVJGF 1g9 aX",rdGKnS, v CUKI),T BTW,W1 S R.OTIvWCBM,WCGM
6 MOO /')/ GDA,NH'OA,f;AI)i US, C:.,C1,C2, RAT [O,TAXL, A0, A1, A2,RPft, SPEED tI t SI?r:r ARvC-FFD14tR12.JYSTI vED1 tBFI. WNDUFREQ.2P(',G'•1,J'.tl'4lNtVCP,MOT,CB-MC'JF - CB'1FR'` ,CDMO,CBMI,CBN2,PCS-I,VCGMINiV:GMOT
3M .1_r^ C ,;MVRQ I CGM0,CGM1,'.,GM2 I EB ARM, PBARM,EFFB XFSM,RUN0,GRPR,^;.::PDI, GS^'w)2, vJ_D,C-,t4T,GCUt,GBAR,EFFOG,uRI2,^oHYSTI,GEDI,GBRI,GWNDI^5 ,(.F k i' ^9TX-ih1, TXIAR2,TX4R3,TXAO,TXA1,TX42,TX3AR,TXM T2
;3t•1^'i^V /F/ '_` ST)'9,CUSTAX,COST3,CUSTFtCOSTCB,COSTCG,COSTG,COSTXHi!1-; 'J /F/ 'SA( 1390),"JFL,,3,IX3.FAMP(13'9 9) I YLG. nG-tVHG
DI°"E 'IS 10N 1X1(15), IX2(1(+),IX3(16),V1(1390),BAMP(1390)I F ( N F L So \1 E 0) ;, `.L T Q 10 U1 11 P=
I V2 ( 1) = 5. f T•1 is ._.. ..^IC3(2)=5HPZJ1')UI X3 13 ) = 5 HL S IONI X;3(4) =5 .1 SYSTI X_( 5 = 5 H L= '•1 C J Lph r)1 X3 (6) = 5 4 R R F" NT (^P LYelf
I x z (l I f )='; 1 i ' F I ,t P1 Y 0f T
IX?( )=r- 1HROA T i(7y' is Any ^
IX3( 10 )=5-ITTFRY
I X3( 12) =^HA FLY__.._.___...I X 3 (! 3) = 5 .1 w 1-i E E LIX: 1141= 5H LtUFF
ARIT=: (16, 500)
API T' l it), 5 ,02 1
ii RITZ: 16, 50315)) F0V'lAT ( 5+1 .1 T H IS ROUTINE GIVES CURRENT OF THE = LYWJEEL BUFFER AND)5U1 = DRYAT( 54H SJPT^.?CTS IT FRC'M CURKENT, DJRING DOAN TIME 15 U 2 F G k A yr ( 5 ,+H BATTE31' IECH A RGES FLYwHE EL. s BKAKI NG ALSO CHARGES 150? F()F 1 1AT( 5' li YLYv., HEFL. 15 04 F l:R 11 .^T1 4 4 ,C E PS SUBRUOTINE VERSI ON 2 1
K L C ^ ; X = _ - GR PR *^ .1 NFLA G=1
C INLTIALI7_E VARIARL E F2k FI RST TIRE IN ROUTINEC SET FLYHHrEL MOMENT OF INLRT I+ IN' MKS UNITS * F+CT]R .66 IS TOC u31PENSAT': F3B f LYW AL• L L HOUSING WEIG H T.
F iV=' . ,,4 Frt;S E/(XF= S'! *2.*P I / 60.) **2*3600*.66C3i1f-FC^I=.'i5 ^''^JV*^?.CafI^74b./FSU./32.2f'ER=>;F ^= SE *3600.
_ XIFS=.74:3 xX FSH*2.*PI/60.XF S = X1 F SXFS'14X = XF SXFS AIN=XFSFF = . 5*P I N* (XFSt:*2)
100 ::)NTINl.IEIF(A.LE.1. ! GO TD 120PEUF=(A, VA46 JFFER)GO T3 10
120 ' PBJF=3.--
IF(P I).LT.0.) rIBUF=PU,130 CONT INUE.
RPM=XFS*53./2./PIIF (M-T)(NNP06).NE. 0) GO TO 190 -^4 RITE(16, 260) FE, RPM
^: _—
_211 -
= ^' 4I ^A) NNO'
1 ) r' ^R^i A T iJH I L YW J Ll L. LNE PS Y 9G15*5/15H FLYWHEEL RPM -qG15051C A LL 411. 13 C J P.
i^!;Aj I
If ( L r. 6. ) Sf. TC: 140IJ Ff- I ,,',J P *P I iJf*/ AEt S (P 0)
U u r- ='i C [Y- - tl LJU I
I I , i P lI 1 I .IF =F 13 V t: 3 UFF- I /E F F n.^. *D T*! 000f 0 F-F.= F-E- 11V 'BUFF 14*FFF3G*DT/ 100o
r L— f i:-( RUN011 0,). /3.00.*QT* ( Fl-1 FER )**2 J
i ( N ,,ii t)o ) 3 ^. rD 170
Rf CH= I F 6 *2 -X r S **2 ) ", f Iry /2. / DT
11 (VA. t-). t). 3.I F ( A B5) h r.0 I i o i3T K K M A K ) It EC H= R EC H *p. E C 4 A X A B S( I E H)*B
' LIE='-:• C,-1 I ve; f r F E 1 L) 0 . + B C d R
F F-= F 1:1.11 9, D T
170 XF S 0, F F / F 1 1, 11 5
I I- XF S..; To .kF S ,16 X) XT SMAX = XF St F x 'r .)(F. sA iN ) Xl* S4 I N=XF S
I T, * ( K 1";' 1. '-T-.-X- -1 F, S-711 -Y G f I I r, I I t3 -Y—I N T 10 WK f T F 16 9 2(-, 0) F F: v RPMo F I l I S ) X FS A A X =X F SM4 X *60. / 2. /PI
2./Pl1"E", ( 1-6 2 7 0) X F S 11A X i X F S M I N
%7J F,AM - , T 1-3 1-iv, X of' EL " 15. 5t 5Xv 17[iml No FLYWHEEL RPM= t Gl 5 -.5_- " . --.- -- --.. . -tT A MP( I =PS A ( I)-I)Cj 1t
-4 F T IJ T:, \11 4) 'A J TT-I R C j
3 u rc 15
)-go ii 5. f T, E T T. , 50 1,111 p XI F S, XF SU LL L'( 11'
FFT-Y'N I —fl-L F-l", AN 00WN. (I ALL F D EX IT IN AEPS v ***v 3E 15. 5)
S U (3 KPJ T I '\' E N 0C. C J R1,,i w /A/ A 9 Ah I S L:, !I V, c r.), DT r F C ( 2 0 , 15 0) r FS E, J FL AGt MHP9 P,
^TA' A X S U I P, F S Ul f- r t S U MF F R t VA i V N , VT
2 SU I k,--oJ'lFFl l ,FfJ ,lFFN, PICF, i-)Llb,PFYtPbtliPD,F.'),EHD,DELF,6,.tPBAR
' UA D, VC , T OT E , X MPGl/1 \ 1 9 1 X e" -,r-4 T S , R A ^ 1, ESi
C, \4 K, ;, t S Vi Y , W T :-: S T Plk 0 P 9 W 4 X ► W M 0 T , W T C B M , W T C G M , W B t W V W F,W GE- t J I K A -3 V'";S 4 CJ RB, T ES I- ^4, 41, S , itnl' I WC BM, WC G4
:C11 O4`! /'I/ C ! )A , R: IGA, PAD I US , U , C 1 , C2 , RAT 10 1 T AXL, A0, A 1 9 A2, RPR V SP EED IS P Ll v *r ,-, u^bm , v mio%k EFF DM Rl 2, H YSTI , E0I r BF I , WNDI tFREQv
PC b 1, V `';-1 I N, V rCti-kik"J , CL31CJH , C3NiF J J r CBM0, :3 Ml, : BI 2, PCGM . VC GMIN , V: GMOT
EFFB,XFSM,RU14D,GRPR,4GSFl 0l, tGE0I,GBRI,GWNDl
G I - RF'),T.X-lRl T^ M14.21'rXM;;)3ITXAOtT)(A!,TXA2,TXBAR,TXMTQr , m,., /L:nST01 ,'. OSTAX C QSTB COSTF i COS T CB, COS T CGi COST G, COSTX`4
CP'44:01 /F/ SA( 1390), VFL^^, , 1 X3 1 FAMP( 1390) 1 VLG ir VSG VliG
1 ) 1 f"IF N ; I ON IX1(16)vIX2(16),IX3(16),VI(1390),BAMP(1390.)r THIS CALCULATFS THE CURRENT AND POWER FOR AN 'INOUCTION MOTOR
C SET IVI If 1°,L VALUES D , I F,,. r-F U I T 4\11 10TOR C3NSTANTS
DIMENSION GRA(4 I
E ^ L 10, 11 , 1 1. 1 4
RE AL 10X, I OY t IOX I , I OyI+E A L 12X,12Yil4Y,I1Yvl1X,13XF-L UF ( X) _ ( 5. 7*( TANHl. 3,82264, X) + , 1033 * X + 95
AX I ( x v Y)=( S ^aRT ( ( X *4 . 3m6./Y )+.38. 44) 6 * 2 ) *Y / 1. 2396
AX2(X,Y) (SQRT((X*l?.*5oB5309/Y)+.25) -.5)*Yf13*7062AX-7 ( X, Y , Z X / 3 b 1) 0.)*(t Y Z 6
AX i X , Y i Z X *'Y J / f 3 60 0 . JQ 2
I F VA. L Q. 0. LJ F 0 1J00
212
-7
NN P ow(IT IN 16v134) I X!
poohdLUIJ^16^20 I X 2
1 3, 4 FCF M Ar (11-11-tlyjljA5)W4 11'. (i0tl4t))TFST)AgWlltkA,TIO;TXMRIYTX*MR2tTXMR3i^Pk
- 14 0 pf,,j o Ar U ?.X 9 2 31 11V kfi K* L17 TEST WE I S I T jF8.2t7il POUND1 1 x i ". I I W, -T 1 C Ly----v ULi!' I -t F8 .2p 7H POUN DS2 1 X v "',I It XI-_ '^A T 10 •F8.43/1 X FITRAq S ilIGH GF^ R F 8. 44 /1 X-1 2 3 4 k A TI VJ' SIC. GEAR 9 F8.49 X ___ ----Li - Vi GEAk tF8#4
ROTE) PNERPUT WPlJC- RUJTiN.I.-111: 14' Ft',, k CANDIDATES
vb^ ll*^( 1.6 7 130)l'.-5 F(,K ,AAr CANDIDAT6 '43. 3 PDLYPHASF INDUCTION MOTOR 3 PH*
1151A T-(l S SU l5P%f , lJTlNF DATEO MAR. 28 91979. FCYX = 6o
ACCJP P 3) (.0@/(2@03*14159*RAi ) IUS/12s)1 4 3RA ( 3) * 4 4 T 19
GRA CR 6 P, A i --- * T X'A R 2.,PA 1) F A (3 T X M R?G V A 3 G k 4 (3) , T X I i IGk A ('T 1^ .F L/ 44643F-G2F-I.JX F L. X 0-LOF ( XF-LX0 FLUX
SET SHIFT PrDINTC SHIFT P;'J^)JS 417AD IN AS )ATA.cc VLG = 19.CC VSO = 35oC PER LF,, Cd k'.k 1-: \, T.S ::;N,) L3SSFS F'-)(( THREE PHASE INDUCTION MOTOR—.-- .6c V'I*=II V* ( .5 **0 5 )":49)33
El = 4" VTS L .1 p = C j T04
SPFF ,,); SPEI-Dl / (I. - SLIPURRI = APR A SPFEDiXLL).y S = RP4*('-))./FFF)ll - 1.)'.' Uk ;l f, l = (RPR+Xt.(jSS)/RVT4- X : UR ),MFib AC. XAMAX = OLLIAD*F(" I 130./(3.)**o54 lj )J. = XL3Sf,4. lqN)l /1.00.,HYS1 = Xi. ns ,,- *HYSTI/1.00.ED!= XLC ) ;)S4 ,
.'F- 01 /100.
3f : 1 =X-ISS'-^Fl /100.WtN)DX = (Xl.C)5S*oqNDl/100. SPEEDI/3600. )**2)3F = t XLr-)SS*Iifl /I 00o SPEEDI/3600.li YS X = ( X- :) S S* H Y S T I / 100 . ) /A. X 3 ( S P EE D 13 i F L UX 9 F LX D)E L) X = X L CIS S -"'F D I / 10 0 o AX 4 S P E E D B FL U X F L XDPF = T:DTES 14 = ( I.- PF**2 )**. 511 = RPR El E FF04 100 F*3.SNI i 11 SN
C PEk LFG _3SSESXL6SS RPR* (1J)./ EFFDM - 1 /3143 ^ T HYSTI + E) I ) *XLOSS 103o*Fl IBUT 1 2 100 *XLCSS E 1DIRT = ( ( RPR 3 +((HINDI + BF I ) /'100 * )*,XL3SS) ElD H4 1. SLI P/( 1. SLI P) ) *0ERT /BDkTIF ( P114 L- E.) G3 T3 690
213
fc—F TP14 ItUrl!
Dk T = iA 0 4 T L C . TCS 12 = fk ORT + 0 F 12 TSNI 2 = C Sl 2 (2-5 (2.5**2 -1.)**.5)S N 10 = S 1 1 SNi 2RI = irRT * F*l / 11 2
k3 = F 1 / Ab P TC. --JF.Y ITf=R AT IVE SCIAEV+ F:)Ik_L.:e.tiOtR29lk3tXl t X2 f X3 t AND E2
PHI = —.04
P12 = 904
2 = ( S M 1 2 CS 12 **2 5-1 1. T-12S
__..._L '-1 (C'9T + '-)ERT)/ 12 -^^*
X 3 = E1/I SN 1 0*( 1 HlK! = Plil X3X2 = u-12 X34 = )
P F! (lf
C S 10 4 3 R TY.11 =9--1 1 *), FXll I I ,, S N
Ylo -,SIOX 1) SMIJ
10 = C, S I Dt 4, + SN10**2)**.5t2 = S1 2 + SNI 2**2)**. 543 El /SnlloXI "A
IA I
X2 ' -1 2 X3S A=S 12 12SA _C S I 2 /12
610 :DATIl0---X 2 <1E 2 1 21 X2(t 4, P 2 S* *2 5
c. 2" : 2 BI T*E 1.14 U/ R3
. 1- 3 ( 1 0 0: - 1 4-** 2 )*+. 5X 3 F2 / 13SNB = X?/((ik2S**2 + X2**2)"*.5)C S ri = ( 3.-SNB**2)**-,5S A C = SJA*CSB - SU * , SACG (SA * CS F, + S NA *S NBF, Z
FA =-( ( E I E LZ' S G '-_412 + (E2tSNG)**2)'V'*.5X I = i--'2E!**2 11 *^ I **f"I F X1 . ^T . 0 . X 1 = ( K -1 *'- * 5 1 11_.,I F( Xl LT. 0. 1 = , 5-11 AB S( X 1)Nj + II F l N. ; T . 2 J) GC., TO 622lF4A ,3S(X2-Xl).GT.1.E-Ub) SO T(--, 610G:) T3 620
qei = cpmuk r ( /2 5 H CIRCLE. DIAGRAM VECTGRS * f
I 8Xt2Al1t12Xv3lI0 t13)(921il2i13X92HE2913X934AB 911X93HBC •2 1 1 x I C D 9 11 X 9 3 HD ,I---
6^0 WRI TF( 15 1 92)) SLIP
920 F D R 4 A 1' ( 1. 5 A SL I P E XC S S I V E tG15o5
CALL FK IT622 WRI TE (1 E v 986 ) N986 F524 T (IX915)52) CONTINJF
10 = (YI Ovz 4( 2 + X.1 01 2 5
PF = 0 F112 = R2S * SLIP
ABRT = Yl 0
I
214
--I
q
RC KT = Y 1 *X 11 0K10 - A 7 -RTT = R2 * 12 **? /F-I
)ttr T = ORTWk I 1* '-'
-
1 1:x, 934) 11, 10.12, =2, A 11 1 T 6 C R T , C 0 R T 1 3 E R T
E X
I 1 2 9 1 Q v ELj-L2- t P FI T^733 FiTi-^f -(-/ -4371-i C1KCJ!1 C.P`JSTA")Ts, ]HMS PER LEG.
1 X Lf^Ll 1 , .! -LJ X_t_3 H RZ 10 X , 5 HR3 -2-10 X. 5 HA 1 Alk&L-i 5HX2 0 X f '5A X Mv6315.6428H LI:G C,J RLCNI T S AN 0 VfIL TAGF,r I ) X v 5 H 11 , 10X 9 5H 1 2 9 10X9 5HIO3 10 X t 5 H E 1. 1OX95-A 2 —^-U.—tIOX01PE /lX96315.6 I
•cP R I NT M IT '^HAP AC TrK I ST 1C S
4R ITE( 16 t 980),dkIT E(I!^ t 992 1
9FU = CR II 1T(///23H MCT3k CHARACTERISTICS. 124H CANDIDATE NO. 3 THREE19 22-11MIASE M)JCTIDN 431 . 3R / )
982 FrK'A AT( ,3X 9 15H 0 Al )'D PO4 ER 917H VOLTAGE 915H LEG :URRE14T_- ,].7j ^CJMR SPEED RPM t15H LEG RESIST2 9 15[4 h'.:31 DR RESIST 15H IFA- TANCE X-'-
A C. V T
:IFI' IR E S 4 13' SS s p -,: Lr: J I
RFS ^2AFI TE I 5 P '*,3't ) RPR i AVT r,.CU R i kr-C t- BASS 9 RES At RES F ? X341 1 TF 169989)
9 3 9 F4" RM I! " 'Fi-P F-AK I N G FKIC T M 916H EDDY CURRENT11 !-1 A Y S Tl R F S I S 911H vvINOAGE 9 19H LEA(AGE REAcrANCE2 1 51 _POWER F'IACT(*)K t 1 3- 1(11 SLIP i
HYC,-!,W\JDI,Xl,PFpSI-IPc 84 FrRMAI'(!X i 8u' l5o(..
C A00 TO SJ 14 C AIQIUTI !^ PDRT1311 T r-I C6L'w'ULATE POWER AND TORQUE AND EFF.C AT VARI -)JS A.1 CiJ NT S 'IF Si- IP AT RATED FREQUENCY.
TW".)PI = 2331 135SX = 112/ 1** 2 + ( X1 + X21 ) **2 yv * * 5
E L SX / 10*SLI PX . 0 10001 DFLS — OELS* ?- SX,4K ITF( 107`10)
3 1 l ri R;";%T (/ 3Xp 4 HSL IPq 129 t 3fiNPI 9 q X, (-IITrII QUEv 1OXt 50DWE I i 8Xv 7HVOLTAGE 91 8X91 71ir.JR.R ENTq 4X 9 12HPDWER FA -.TOR 1211 EFFICIENCY
0 1' ,- ^ 5U J = ' 1 t24SL I P X = S L P X + ] E. L S'k 2 S = %"IL SL I P XL (. --= +1 2 E 1 Z:^IL?.' = 12 X2 Z212Y = 12 Re'S Z2I =- 2 X3
I e+ Y = E2 R 3
11 Y = 12Y + I (+ Y11 X = I 2X + 13 X11 IIY**2 + I !X ,**2 5
S P9, B 11 X I IC S :3 11Y 11
El. Y 2 + IIY RI + TIX * XILE 1 N II X Rl IIY X!
F IV l E 1 Y 2 + E 1X**2) 1111 * * 5SMG ElX ElN
3U._+_W»
^12 = 12 * P41 , .
-_-__--~~13 13 F AC
11 11.E2 = FZ FAG
*
t' 0-- _- --^, ( 1 . -S L I FI X 3 * /SL IPX- v * (R--l3^UO°
TU8 t'r F< y kTv;0P K /6 EFF (3p«FI*Pf:l * ll 0
_^^2 _=_l 660 ^]NTy^JE12S_ 16ArA_l^2 ^[kMAl lX"5UH4GLUN° VENYCLE GE AR AbAD MOTOR MUTOk MOTOR 43TJR
1 9 62H 4
l& 60^n^3T S P^WEK POWER SPEED AC^__.'
4v6JU^^ LJ4^ ^J5S LJS^ LD3S LUS S POWER CURR EFFXC EF
1, X, & O^ Al Ll S T/SF',' WATTS WATTS RPM VOLTS AMPS TOR WAT'---'---
T ' 6UH^ N4TT5 W^TT9 WATTS W AT S WATTS WATT8. A4PS PERClr PFB]---_
-^
N= lI.`,*°,.°...;" a0 1 10
------
` T ^^'_--_---- - IJ /^=3
^O 73 }O ^
' `.'-'.A.'^.---'-. ._ - .
NX=N^
AXPk T3 ^4c 2. 3 l y
PMX RPM
DFXM = PUu
44DX l4 = PDX - HFX4
HV8=(^iV Ml 5**. 5) -- -_216
'|
F ^ I V I. i I f-AIT
I ^il -)f I L C T *i-",- f CA-C-74-C-1 7 TUF 0 IKON
ITEP4TIVI: S"IriFfIF. r f I,R MOPIPI. cuRp,,rNT PER LEG AND FOR PO4ER FAMRS3vX 3v^PPL PDI 3.
TF4,, CI DI 1 PS L I S I P T D P. T D RR T
X X= 0
•S X 11,111Y OF THE
IS PZ30R
S X 2 = SI F ( 1) P 1. L 1 0 S X = -S KIF( ") X,LT.-*45) SX=-.'r5
XI+X2) *RP4/SPEEDB)**21*( 19+29*SX)
IF(PPL.-T.J.)SX -=42+',)
If' WIIS (SX)).31*o0.!) SX=.I4rSPEE013/RPM
IF(AiiS(a' X-SX2).Lr.'-,E-,)7) 1;iJ TO 630648 C 3 V T I5- 3 CL I NT IAJ E
N N I- If f A ll S( S L I P X) T. SX) SLI 1) X=( Iv -o 1* 4, 110 SI GNI SX PPL)RP A. = RP 'It ( I . S L 113 X0'P F-I=r^', PA / S D E FON
1 F R P A. I . S PE E D3 ) B VX = B V3 1 1 0--- XR PM#- 03)El IVX —I!'(N.E(-)*i) E2 = ElR2S R21 / SL I P XL? ( R2 5 . "2 + (X ? *K RPM * ,"2 **e 51 2 F. 2 N12X = 12 X 2 OR PI )/Zl 212 Y = 12 R2 / 12I 3X = E2/( X3--', XP tIA)
14Y E2 3
11 Y 12Y + 14Y1 1X 12X'+- 1 3 X11 1 !Y**';- + 11X**2)**.5S N B T1 Ii
C S 3 I 1 11'E1X 11 X rF 31 1 lY *( X I *XRIJH
El y F? + 11 y R! + fix *(XI*XRPM)
E I NI ( :: I Y-u,,,1 —2 + C ! X** 2) 4L *. 5SVG E, X / ElN
SG = El Y / El NC S4 = -,S3 A S S N IB r M;PF1 CSAF A 1; F-1 /CIN12 1 2 * FA(:13 13X FAG14 14Y FAC11 11 * FACE2 F2 * FAG10 1 3* &1 2 + .14**2)**.5KAI' (12*4-2)*R2/PPLRAT2 RAr*(!.-SLIPX)/SLIPXf- -(PAT2.'j T.1.)G0 TO 632IF('4 XX.GT.0) G3 T3 634SLIPX=(10-.5**(N+1))*SIG4(SX93PL)
217
G:) T)
Z 11K X = 1
14 1 !"X= S t. I PX / PAT?Q \1 T I \1 JJEI r ( A A S ( ,t^, T 2 L *T 1 E — U G-1 T3 640
I = l a:i S(';;, A T Z — F ATX).LT. 1 . F-38 G (J T O 6 42TT=
I F ` ,J,G ll' 25 ) GO T f ) L42I Ai\ 3 SL I PX LT 1 E- Of; GO TO 644
—__44
4 1 2
11 10
[PiNIX 2 J, PPL-a 14 DX?-', -f3f-K ki
R 1 TE i I& 9i)1 "DI AtJ)MMX
D I FJ K 4 A T ( 1 1^ 5 H* ye C X; F SSI VE POWER REQUIRED-.-; Kv23HRF'.lJIRE) '10TOR P0vFK = ? Fl2o2t2lH 4VAl-A3Ll.-- POWER
`)F 12o l)
640 Clj\,T*1,4JfF2 13*X3,.XP,1-1APf- X pr I
FLUX = f*?*iPEF')O*FLXI)/(r;l) A-O FXI
XL L)X = 3 F: L UX)x (
I T.., -A -tj -X
I- D f) Y=,- )X VX R P A 9K LJK v F LK 1)
I F ( A 11 Gy T. ( A 1 4 X / 2. 11 11 AM AX/1 2 A B S 11 1 I
I F ( A "I C•J; ,,, -3 T o ik N AX ) B C J R BCJ R * AM A X A B S B CURZ D N T I 'q J,I F I ( 1`03 T ).a`4 P D . L T 1. 0) B C UR 0
_—__-
X1 2 1' _ = 11 41 2 Rl + ( I :2 ,f!2 *3
IF (,'i-',J K-L L-.A;IAX ) GD TD 530I Tr V,,9301' CUR AMAX
f, Lk 4 al KX 1 2 1 2R.- 9'( 11 2 - ( Au A X /?:!) *R.1
P3 :1)11 + X1 2R EDDY + HYST + WNDX\,l + IIFXMP13A PB
I
SET PGr& LOSS Fflk CONTROLLER
--PLX=J J\IL*r, IJI L3 SS t -)BA SE=34 SL JUN'. I'l ON
LOSS, PSWT=SWITCHING LOSS(Ci3'-ii4--ACJR)+( (ZF)l2*A'CUR*,.2)/9)
PIAS(.«-r.J?.",,(ACL)^^/90) )'AGUR/5
P SWT c, ,i N, *L,) v *J. . 5/ 1 ajo.P BA = (P3X Pl A F +PS,4T ) *1 1 911 il = i)'l P F3 X
PBMAX 1, . ,'-0LUAL)-kPR EFF:)MI F 4,-3 S( P I ) e 3 T. PBMA X) PB = PlA# PBMAX I ARS t JPB)IF AFIS ( BCUR GT 1 A X) 3 ^-Ul = 13C UR*AMA X/AB S( BCUR)P B Ah; P f3 Li 1131 F PiA F R 1. E-08I F ( !? 1) . EJ o.) 1. E- 08
I AC.JR.:;T. AMAK) viRITE(16, 930) ACUR, t AMAX
9 -'0 FDRM'aT( lXt 45H*4-*l:**4,*§: EXCESSIVE CURRENT REQUIRED •
1' k ,, 23 H R EQ.J I R ED CJ RR ENT =VF11.3t2lH AVAIL. CURRENT •2 F 1 1.3)
SJA 3 = SUA I +VA *) T/ 5280.PDIH = 1..1:-08
IF(Pq A.EQ.0.) PBA = 1.F-08VIEFF =
218
-A,
----~ ~----^7`-F
------- ----' - ' ' ~-~ - '
-___ -_'--------P-KP1)i'1°;-T°0°) X1FFF=I00°*P8AyPD1M
*
' ---- -'-- - - -^P1Yt(l^,l40 )TF B4p
I STwv^,RATl]/TXMR 1*TXMR2 TXwQ3vRPQ '^^^'^zo1^J(^^
A 24J 7]VT[`IUE
nuI [[ (l^,l]8) S( JPD^VA,N%, n D,PDJNv RPM ,0VXt4CURvPF3'
Z, *'U n lrUf : X'4^PBK ' PU,P[UK,X'A EFF'XO[FFiACCUM
F TJ RAlo0<) qCUP=J"
K P4 0.
-~---
-------- ---------'-----------L39 y 0.
—1-1 1Y S T 0.^l = J+
----- --^^Dx1 = J°B
/
THIS-
['----
-^,
lP "'AK PD1 k-P i
)I kIF 1,151 D\1 IXI(16),IX2(16)iIX3(15)YV1(1390),BAMP(139D.)G) TD 100
151F,,ACCE-EIATIDN AqD B^AKING, FLYWHEEL RECHARGE 0C 1.URS WHEN A=0. J
pf 3.14159265
KEC'M4X = GRPRO °37219
_7
C . SET F~ ~. ^' - ` ~- ' E ~ FL v 'l -hlC- l- L '''`'"''.- nE^°''.°
~~----
—_ ° 7U =3M4LL 'AJ p FA[ = °70*Nv,^Tl*746°/t50°/32°2XIF3 7 c: *X S
_ I*"-'(!) = -)/{ T|il^
.5 H PPOG^
f IS^FS AlXY( 5) = T1 3AD41,
= 5HOJTY^lK^(7) = 5 H TC
=5 ^-- ^---_ %XBI 9) = 51 T1E
^-- -----
`-- ---__- ^. I K 3 (13 ) = 5H Pr-4E
-__
' --- I X3 0-------`-----------------100 --l\lTlUF
)
VA BJf,FACQ] TD 138 ^' --2--------^-- ----^---'--------'-- '--------'---------- — '
-_--_.- .
-T 7
R EC H^
P.
GE E
RPM XFS/XRC
4R8TE{Y61260) FE'RPM.22O
C.; NN P = Iis POOR
)i HP A q P f f PoUl I PFLYtTREFF5 ;.7 H IF F, 5t59. H P DJF .G15.5.
1 9 .1 P L Y 1 5 f 9 -1 T R k F F v615.5 Ill
2 s k( !J, B
rl 17*F IlF LY A or FEP*('?JNJ/ 100 . ) 4, DT/3630. )*( FE/FER)*jl 2
r -s—) W R I T F ( 16 2 (- 0 ) IF E I R P4L 1' I F Yb,, I E r 1, r. N r- f. G Y Q15-p-5115h1 FLY41IFEL RPM =*6I5.51
AFSR t T J IE ("D
— F : J %JCT I J4 ('Vl FF( Sq RA TI U, TI.)RQk)E I T0Rf%ATq SPI NT ,CREEP, VI SC, SPEEQ)
TH IS IF j i•,, cr i rim GA v ( i T HE FFF K IFV CY 3 F l C 0\1TINOUSL Y VARI ABLET PN A N S'^ I '.; S I QN.
C RPS IS SPFt') '-'F f q l) ,.JT 1V Rt;,-'IANIS PER SELOND.-; IN--j (^-Aj F [ _S— ICI
T(IR,)JE.C, SPIJ 1" 3011 Tj,t„ i K ['4 f l c_:Cr_P,'T JF RATFL) TORQUE.F, L P P I PF ,ZCFNT ( V l: F P AT TOME.
f; PlWPf'QSIL-NAL T( AS PFRCFNT OF RATED TORQUE AT MAXC S P EFOC S P F F IL) 1 3 ^ A TF 1) S Pf-.- 1: ) IN RA 01 A N P E=R S ELON D
x i-Do— IS 2 * P I TZ ') Tr; I ? kjU I':..
IF ^J !:, E^ IjL T'^ 100
T Vl SC"TGKl'AT/lJD*/SPEF)
= ?,IRQTTG) /( ?.-SPiNT/1)().)FCP"^.j
I" = AIIS ( T[ ' It JJE
rGP ' i;1--=(TLJPi)U4 )ET*RPS - iPINT*l'QRRAT/100.)*f3T-DRil TDRQUA NF TI I F F.0 T('KIJA .25*T:)R[) 1,
SPIFFF I.-CkF.E-PAVTEF='f%tN' ,EF 0: SPEFt:
R F T,' .Jk'4CVTEF = 1.R 'T 0 L^l INE DS J BRUJ T I NEJG ( 3('^J R:UNl 4d\I I .Al AvAFi'3SFqBV?:) i I),TYFC(29ti'J)rFSEYJFLAGPMHPtpt
2 SJM*),": tS IJ'^1FL-1),.,iU'I FE^-NYPICL,-?013YPf--Yi PBvHPDsFQVE-ii),DFLFC,P BARI V 'ITS t PAN,;E ?S.JMD,Vr.' iTOTEtX4PG
0,"'IIJ. /C/4rxM, lv(;RnS, ,4CUR5qT E^,T N t olPS I ROT IrliC6M, 'WCG\4
'.1 \4 11-'J 4 /)/ Z- DA t'--l0A,K,5D I US t C9 I Cl iC2 7 kAT WIT AXL i A0 9 A 1, A2 RPRPSP EEO Ilt .;P El-L ) ,A, "j- -l A00VT,CJRD^1 I d3 A R,EFFOM i R I 2 t HYSTI Y EDI ,BFI # WND I I F RE Qv2PCB'Ip\i(,I3Mli,I,Vr,13t4LITgCBf"ICJ!,,Ct3MFRQtCBM0iCBMIY CB42,PCGMtVCGMINYV6',GMOT3 t 'Z Cp I - Jk,-.3 lF RQ I C.;flo CGMl,CGM2 EBAIRM, PBARMi EFFBtXFS4 RUN D,GR PRY(is p0l, G3Lt),GRVT,GCJ2 GB4R EFr-nG 3R I 20HYSTI GED1 tGBRI GWND I
5,GFr, F : ,) I T VAR1 1 TXMR2 TXMP3,T' XAOtTXA1,TXA2YTX BAR YTXMTQCOSTL) 'I,CGSTAX,COSTf3,COSTF?COSTCBgCOSTCGCOSTG,COS TXM
(- C4'1 F/ PSA( 1.J-90 ), NF LA.3 I I X3, FAMP ( 1390 ) I VL(;, VSG VHGI Vilf NS I ON IXI(15),IX2(IL,),IX3(16)?Vl(1390),B AMP ( 1390J
Til f S R:J LITT \4-= C A LC ULA TES THE CURRC-,NT A14FJ POWER FOR A SHUNT WOUNDC SFPARATtLY E:KCITED DC '40T3k*
sur INITIAL VALUCS OF CIRCUIT AND MOTOR CDNSTA\I'T50VAL-l`I')IJN 3RA(4)FLJF(X) = 15.7*(rANH(.18226*X))+ .1033*X + .5)
221
_..A( tY) 1^033416.%_Y)+38,44)_-6.21*Y/1.2396
., h^l Yf - 15 tf1(icx'^+.*c^-.is5?f)^/Y/Y + 25 5 *Y 3 7062AX31X,Y,Z) idol*IIY/ZI**1.61
.._.^......... A X w ( .Y t e 7- = . _t t XLtLI 2 6^7_)) * * 2IF(VS.f`:..).1 ,,D r7 1000 -IF(SJ''+)."•1F..;;.1 Gtr 10 41
( NUT trl<It I , IJT I NIE Fit-lf- FOR (.AV MATES
1!^IT4:f ^^,: ,J )TI':iI r,i )16 tAA I'l arTX'iR1,TXMR2 TXM12rRPR
4o"C13'^I'a`Ct/1K,23AVI:.l_lf LF-- ICsl HI GHT ^jFE3.2 1 7H POJVU_/1X, ?.i rIi..,ITE'= KY A i :I iii r _ _ PF8.2,7l POUNDS
P. x f ?? tl L0 GFA^ F8941'q
51'f:! RATLJ_Puwl:R. --_ ^ f80 i —
+^I -k I T is ( _.._.__.
13(. Ft)R'g ATI:: " +'^'I C,A,jjOIDATL_- NC, 2 SFPAI?ATF.LY EXCITED r)c MOTOk.1271+ .V,, i t V LIF J
AIN. ,Y.et, 1 079. ,3HFCY_ 1 —
X = ..) .
;2n( 3) - (.') . /( 2.' 14159ARADIUS/12.)
GP AQ ;i,A(3) TKM11 2
GRA(a 1 = uKA 1 TXHK1
ESFL= 7.1' 1ki
XI. CS S_ = Rin i: ;: (1);)./ Gf FOM - 1.I- C
__ SCT FIFLJ
—j^^15T9^lc;I. Ta GIVE FIELD I**2*R LOSSES OF .15 OF TOTAL I2R.
k E S ( X L (ii`i r P-1 —?1-f U O .) _--^FIB = X<rZ cS /2VT
kE S 1 X3 )*R E X 21
6 V X = V-!, ES*AC X-(:f 1111F! X = ► dX / (SP Ef:DI-:,FLUF(X11__ ---F 1.JX -FLX f • LUf• (K)FL X!) = FI- J ...
......_..._ fLX22^_ •=_ X '*;i4 ;tT(l.25^02^.^FQ;
TLRESFL =_0T / F I2_l•iYSX = (x1-01SS*iiYST I110J. I/AX3(SPEEDI, FLUX,FLXD)r;VJX =_ ( Y,L^^S^ ir;nl)I /? 00. 1 /( (SPL" Ei)I /3600. 1**2 )
-_---- FDX = ( <-ASS *EDI/ 100.)/^ V 4, SPEE)l r;:LUX,FLXU1( XLLiSS*13 FI/ lUl. )/ (SPtiEDI/3600. )
- F1 R X - =- 1.8*f' I ,R----
FGRZ_ = ' *FIR_- F 1 NJ SA I r 1' PCI NT
r_ C-- NRIFi • ",IOTOKCHAKACT^RIST ICS
. —^-^ - -J
--
41ITE( 16, 98J)—..
WR IT E ( 16 t y 82,f_80 !MOTOR CHARACTERISTICS. 117H CANDIDATE NO. 2 /)
4132 F7RAAT( 3X, 1.5H WED POWFR ,17H VOLTAGE ,15H ARM. CURRE
222
NT t 17 11 ^ 1 r KR! 115H P ARM. REST
2, 151 P IEL) KE.S.I.ST , 15H FLUX FACTOR _ I _ _-r,VT=k!V —KCUI = FQ
AFC. - FIR iL1I'i^+^` tic"'^TF.I"^`Y UP TIIE
POOR;ASS SPEED I
RK -^K_ WRITF1115,984) f`PkvI '.VT,f' r:JRA RFLLE1f >zs.^E:SA,RESEj
14^ ITF( 16081)y 39 F7,,R 1AT(// 19 ti IEAARINIS FRICT13\1 ,16w1 EPDY CURRENT L-
1151 1YSTFRf'SI 9111-1 OINOAGE ,1911 FLJX C31STANTW'V) 1 =XL0 SS , WNJI /100.
~ t HYS-'=XL i )SS *HYST 1/100.C11= ^(LCSS'LI1I/IUU.3F1 = x_C)S5*'3ri /100. -','RI T E(159 1)84)RF1,FI)1+HYSI, d K!D1 'LX a
X84 = CENMAT(1X,8f 15.(: )W k I T E (-16 # ? 2 6) 1 X?
~ 1.25 FUIPIAT (/1X, 16A )«nvPl TF ( 169 132 )
13-2 Flik"IAT ( / /1X, 5m-IAcC UM. VFII^'LE ;EAP kCAD MOTOR MOTOR MOTOR1 , 5 ;) 1-1 AA M T 11 '1CTQ1• EDDY HYST_ 41NIDAGE FkICT CNTR., BATTERY BATT MO
3 9 1 6-1 T D R,^ ^VFi1L Y ACCJN1 /31Xo 601-101ST SPEED ROWER POWEF SPEED VOLTAGE CURR , I*I4 9 601 , 1 4 CUKR LOSS LISS LLSS LCSS K) V1 CURR EFFI: EF59 111E I /6i X, G011 A I_L.S F1'/SFC w^ TTS WA TTS RPM VOLTS AMPS WAT6, 1 HT7,EU4S WATT —S 'WATTS tNATTS WATTS INATTS^ WATTS AMPS PERC;T PER39,9FICT 1J *HR S l__ -
40 CONTINUEV= ^
IF (V A. (;T • V HG) GD lit 10[F VA.5T.'VSi,I GO FU 2)
GD T. ) 3 )10 N3=3
53 T i 3 02) NG = 2
LIPS-IIFT IF ACCI.i.F:F,ATIUN IS ENAL TO ZEKO.IF(A.F').U.)
V; =3
CMIT INJES T 1 1%Pi , 1 AN) Dc<I VF- LINE ' t4[-CI10, IC4L LOSS C;S __._r
NX=V3RP,'A=VA*GRA(3)/1X11R',.PA = PI)UTDK = A0 + (RPM ,^AI. 1 + l t o g St PD) )*6(7.0/( 1.'15-8."v2,*3.14159*RPM)*A21AK Ph= (Ol f)F^*ilI'M^ 2. 3.14159/E-0.) *1.356 xPDT = PA + AXPf'RP rIX = Ra3RP,4=VA,,cGRA(NG)TAP{=TXAO*(RPt44^TXI%I) * (ABS(PDI )*60./ (1.356 *2.' 2- .1 4159*RPM'S*TX4211TAPk T 1PN #(1.+1:PM/RP+fX) *. `;TMI> R=(TMPR*RPM 4-2.*3 .14159/60.)*1.356
`M+ ' P!1 i=^ 3 I+T1f'R-XMPSNU i'1 = PDfPDX=13FX*RPM/3500.3 FXM = P)X
--_P DK =P DX + (4 NUX * ( (KP'I / F,00.) **2)
_._..wN)X M = PDX - BFKM — —.223
1119
PYf_^ j I + A jx'AVx =IV - Cti'Al
t , ^P.14. L T. BVX 1 al *BVX*RPM/S PEEDI* o'k
IF OW l * Lr.Sl l FF0lJ 1 ,1 1 14K 2ol*RPM/SPIE')I*R;)RI PL) I o ; To PM M X) ek I TE ( 16 9 901 PD I I PMM9
C Pi'MI) ELECTRICA_ K3T)K ZURiENT 610 IRON LOSSESIF(fJ DIeLTe)e ) GO T) 21J
f-i-fAL VaL^X 1 ) ;: FI F L) 'kUKKENT AND ITERATION FOR ARMATJRE CURRENT271) F_JX
M=12c-0 Kl FC(MFL0XPFfRvFLX) _-
If- FC GT * F C, R Z H. I , 0 0 1 *F : R Z
I F VCR o G T. C R Z F Lu K f LK 41 (FL u F (6 FCR F IRXL JA = 'C B S( F LJX)HV S T = HY ti X *AX 3 ( Z 1Y. i X L U X I F L X)rio = FoX o tNX + fj pM t X LJX I I- LX 1)
1) X P)l + HYST +- FIDY4- 1
IF(N93T * 3)) (;D TO 'n5
IF ( FL J X.STo Oe ) X;. JK = PL)X/ (1*'PM *FLUX )I F (X CJ it', GT * A M AX ) X C.1 IN' = 1 9 0 14,,14 A X3VA -:7: BVX-(PFS+[A,-, ES)*(XCU•)IF(B0,._Ev0, ) HVA .9**!lJ)*3VXX F LJX = Q A/ PP 4 = I-L.UX-,\F Lux_FR
I F ( A 3 =_ . ) , L 1, F - (K', ) 3 L, TO 240XF1JX
TG () 02 5 C D4 T I \1 IC
I F ( P D I . Gr . i 5 p i i x ) G3 TD 90.)I F ('^- 3 To 3^_) CALL FXI Tc J N f 14 1 E-I F F ( ' i' ^ * L T . f C RX a I T O 2 8
4x \IX -1
GD T3 290RPM = VA*GRA(NX)B V X = 3 V "!•'1
I F( ':PA T . S P E F L) I ) 5 V X 1.1 3 V X R P m PS P E E D IWkIMIS 99?3 ) NX
920 F7) R,'IAT( 200 SHIF r )GWN TO NSGD TD 27J
rivx*.7 j
N X 1(;J TO 280
3 0 TO ? 7 J28U ^^OMT I 'lJJF
IF MiS (K CJ R ) . GT * AMAX)XCUR XCUR *AMA X/AB St XC UR)4^'UR = XCURIF( AF3 13( F rLl2 ) (.J. FC2 X) FCR=F:R. XBCJR = Xt..)k + FCR
BVX/9VX 121 = (X:ul0,,*2)*-< ESi- (FCRt- ,)V)IF((X * Lfo ?5l).AND.(PDX.LT.0 * )) BCJI =003C T6 500
c FIND VALUES FOR REGL-VERATIDN2- COW I NI J E
FLUX = FL.X0l (FL LJF(1 * 6*6 9)RP44 = VA*GIA(l)CEMFM = P.PMM*FLUKXV V/2oIF(CElF4._E * XV) GD T3 292
.-.._. ..^,... --X;. - l MIS( P I)I 1) / (:. F h1 F M 1 / 1 . J +
XV = X V 4• (( k( S+(3RE {i1 *XC) +C(3M1If (Cf ;F Lt.LE.XV ) G',l TO 292Y 'j+'I ;1'Y OF THE'c 1j 27U
21 911 NR IT':( 16, 904) VA vPJ1X34 FUR IAT (4BH INAf)EJJATE C,L)U'JTER EMF TO PRJVIDE REGENERATIVE
12?{ ;fi^ICI N AT VELOCITY = , F7.3 1 12H FT/SEC AND , F1592 9 6A OATTS)K'J2 = 0._--_
53) c c: r.r i v y 1:i = ( ('3CJR, iT, O. ), AN!). (PD.LT.1.5 i) QCUR = Q.Ir- (r•,_ i.. E. 0.) r CUB =—BZU1PR POT + X 12 R + EDDP + HYST + W4DXM + BFXMp '? A = P t3
C S FT PDA cIt L'l5S r:lR CONTROLLER-^ G PPK =J.J!\WT I0N LOSS, PEIASF=F3AS E JUNCTION LOSS, PSWT=SWI TCAI NG LOSS
^<^X=Ci'117+Af3Sf(:f; t ll^i?CUR.1+{ l(6M2'^lit;Uk^^21/4)Pf'ASF = (.:s+.U2*( rj .UR /40)) *BC UR/5PSI; T =3 CJP * !3V• l .f-/ 1. J 30 .PF. X=t P13X4-P' A SE+PSWT141. <'p = 'P + ,R
LICUR = Pli/ fiV^.
r AN = Pf3 / Mi_._.,_ -I1 (I l:..0.) f1 R2 - -Pt38RIf 1 W -EQ.3.) Pia =1. F—UBIF ( PD.1" 1. 0. 1 PO = 1. E— 08 --
-- — —
IF (A(.' f^J-t.GT.A AX l N R.ITH 1C, 901)S'J1:)=5UMD+VA 0TI5280.
[F ( PJ I E. IQ 0.) P;)I M = 1. F:-') 8
XME! 1JJ. * n.)11/P11AX , Ef' r = 10t) !]]/a3IF (P0.LT * 0.1 Xf'IFFF = 100.'P3/PD
^- IF(P)llA.Ll.U.) XlFFF=1J0.*PBA/PDIM_ AL'ZWI = A13Ui1 + P3*DT/3buO.
I F (`"r'i)(NNI', 361 .NE.0) GD T] 248WRI TE: ( 16,1 34) I X1
- -- dKITFl16,1?6) IX2_ WKIT E (lb 1140PTES TW, All, RAT iJ,TXMRItTX^1RZ,TXMR3,RPR_
V,r I T!= ( 16 9 132)_ 248 (:.) N T I V U E
NM P = 1V r! P + 1W2I TF (1u, 13 8) SUM) , V'A i NX, PD, PD I M, RPMi BVX t ALUR, X l2 R, EDDY, HYST,_
14NDXM; 13FX11 PBX, P 3,PCUR,XMEFF,XDEFF ACCIJM1 36 FOR "iAT(1X,1Fb.4,1F 3 .3,I3,1X,3 FF1.0,1 X,2Fi...1,3X , 6F6.0,1F8.O,1F7.1
FU = ACA9t U RE TURN
1000 3CJR,=t).RP 14 - J.
_
AC Uf: =:0.P a I '1 = 0.F3V X = 3.XI 2F' = 0.
_ EDDY = 0.HYST = U.WNDXM = 0.
GU TO '300900 WlI TF( 16,901) P)I ,NMMX,Rf'M901 V-5 RM A,T (1 X, 25HEXLESS IVE PE7wER REQUIRED , 16H PDI AND PM MX = 14E150
15)A = .98 * A
225
V' = V f + A*DTVA = ( v r+ V N)_/Jf'Lt,,► = 1 +
G U_jj.^
JNC T_ I :j 4 U R ( F L d X_1, F I ?-I F i xS F J \11' U1 4 1 G IV 1°5 I HF F I EL 1) Cj..tR EIN T
Ttil S F JNCTI (.N 61 VFS Ifil.-F T r.Ll) CURRENT RCQU IRED FORC A GIVI F-UX
F LK X ( X ) = 3 , 7 *TA'J I I ( .13 2 2 e -*X ) + o 10 33 *X + .5AX1(XTY) = (X-.5)*Y/(15.7*.13226+.1043)*6.J-PI X Z (.X p Y ) = I X- - 2 ) *Y1 (,. 1. 03 3 *6,rL = FLUX/PLXI F l F L. I. To 6 * q ) 3, 1
"i TCJ 10 0
H JK AX2 ( FL t F 1t )GO li! 120
100 f ' UR 4X1(FLPFI,00 F X fCJ4 *6./F Pj
LT 1 -"LXX(FX)E4 FL-=1_T
L I . 5 G T :) I _3 0FX FXf((EF\*FX/ (FLT -*_,z .)))D T:l 140
D FX r FX +((ER*FX/(Fl_T-o5)))1 0 1 F I Aii S( ER) o LTo 1. F-J ) GO T 0 150
1 , n pq)55- 61;i-FX*FIR/(L-.
_P" f- T JR.jEID
ADVANCED FV PRO(I JI-S SYSTEN4 Ao-
___ SINGLE ClOR /)R.AXLE W/TRANS. WF AC118. L}7 6 006 i)0
X300._. .3 0 0. 1.299 X6.0 *30233 1s04
.006 _.U970E-05 9.630E-08 19. 31. 76.• 7 2 5 65 99 2 5 G. 1.50 o1248 o2495E-04 oU066
5. DOE: f 03 72 09 q000. 375. 96. 194, 00050 96.67. 5. 1.J. 9. 90 240. .02 .84j ) 1_. +j 2 1 333 o i8s. 240. 001024
Too .24 00 58 3. 0 040 * DOE+U3 241. 2 ,38.3. 68. 240. 0010311230 3 .75 .))4 250.96. 150 ? 0__. _ 9000 2.5 55,29.18 ?.5. ` L 40316. 4. 500.
0, OOF+J-3 3138. 45 ^ 16, . 200.-F)
241. 196, .0062 93*40o ct) 6 6.6 5.5
'. .000 1o74 '3 0 88 .4158-01 083E-05 * 222E-01 50. 275.,)vAl q Cf- D &V PRL=P, SYST. CrN](.'.Ei'T 02 ONF 110TOP/BUFFER W/CVT 3NE AXLE DR V E D:l
71P.67 e> 00.01 31) () , 1.,299 6.0 00238 1.0411.5 .10 03 1 .09 70E 05 9.630E-08 19. 34. 769
5 .4_444 59. 253. 1.53 *1666 .3333E-04 *0066662 6 . 00E+0° b"+0 ,0. 7800. 200. 96. 237, o0055 90*4 1
57. 5. 80 13. 7. 1 800 4.52 9. OUE f 03 240. 23F. 414. 180. .0012
* 24 .0258 210,4 5 oUJ E4J3 241. r' 38. 425. ISO, o0015150. 3.75 .)06
L96. 150 4100 2.521 9 . I B 55*26 46316. 41. 500.4. F ±03 2 31.5A. 46316. 200. 241. 196. 001208 92.60.0 7. 69 91 30 9^0 +.5100I0 1.74 .3.86 5 5 5 E - oT-. 111E-05 222E-0 1 50.SAE J227 91%[VING CYCLE 45 MPH CRUISE CONOIT ION APPROX. CONSTo P3WER ACCELO
122.3o5 e+ 7 * 08 1•)152 14.16 17.70 21.24 24.78 . 28* 32 31.86 35.4
226
A
37.756 39.973 42.075 44.076 45.990 47.827 49.597 51.305 52.958 540562'5S.119 57.6?4 59.111. 60.551 61.959 63.334 64.681 66.00 65.00 66.00__66v 65. 65. " 66. 66. 66., 66. 669 66. 66.66, 66, 66. 66, 66, 66•. 65 . 66, 660 66jL--65. 66. 66. b6. 66. 66. 66. 66. 550 66.66. 66. 66. E6. 66o 66. 66. 66. 66, 66,_^66.00 66. UO 66. 00 66. 00 6h. 00 66.00 65.00 66.00. 65.104 64.230
63.`362 62.5J5 :61w658 60.822 59.995 59x178 58.371 57.573 51.176 44.77938.382 31.985 25.588 19.191 12.794 6.397
:0. 11 00 06 0. 0. 00 0. 0.00 30 00 00 0. 0. 0• 00 0. 000. 0. _ 0., - --
ACCELERATION FROM 0 TO 55 MPH IN 15 SECONDSo olnT
30. . 53.766 7.533 11.3 15.067 13.833 22.E 25.367 30.133 33.9 37956743.905 43 905 46.712 49.3E-0 51.874 54.271 56.566 589772 609898 62.952~64.942 66.872.__.68.748 70.573 72.354 74.091 -75.789 77.449 79.074 80.667
'221
1, Report No, 2. Government Accession No. 3, Recipient's Catalog No.NASA CR-159650
4, Title and Subtitle 5, Report DateDecember 1979
STUDY OF ADVANCED ELECTRIC PROPULSION SYSTEM CONCEPT USING A6, Performing Organization Code
FLYWHEEL FOR ELECTRIC VEHICLES
1, Author(s) 8, Performing Organization Report No.
Francis C. Younger WMB&A 4500-131-3-R1Heinz Lackner 10, Work Unit No.
9. Performing Organization Name and AddressWilliam M. Brobeck & Associates
11, Contract or Grant No,1235 Tenth StreetBerkeley, California 94710 DEN3-78
13. Type of Report and Period CoveredContractor Report12, Sponsoring Agency Name and Address
U.S. Department of EnergyOffice of Transportation Programs 14. Sponsoring Agency ► 8LX Report No.Washington, D.C. 20545 DOE/NASA/0078-79/1
15, Supplementary NotesFinal Report. Prepared under Interagency Agreement, Number EC-77-A-31-1044.NASA Lewis Research Center, Cleveland, Ohio 44135Richard M. Schuh, Project Manager
16, Abstract
A stud,, for evaluation of advanced electric propulsion system concepts with flywheels forelectric vehicles predicts that advanced systems can provide considerable performance improvementover existing electric propulsion systems with little or no cost penalty. Using componentsspecifically designed for an integrated electric propulsion system avoids the compromisesthat frequeltly leads to a loss of efficiency and to inefficient utilization of space andweight. A propulsion system using a flywheel power energy storage device can provideexcellent acceleration under adverse conditions of battery degradation due either to very lowtemperatures or high degrees of discharge. Both electrical and mechanical means of transfer
of energy to and from the flywheel appear attractive; however, development work is required toestablish the safe limits of speed and energy storage for advanced flywheel designs and toachieve the optimum efficiency of energy transfer. Brushless traction motor designs usingeither electronic commutation schemes or do-to-ac inverters appear to provide a practicalapproach to a mass producible motor, with excellent efficiency and light weight. No comparisonswere made with advanced system concepts ,:hich do not incorporate a flywheel.
17, Key Words (Suggested by Author(s) ) 18. Distribution StatementElectric Vehicles, Flywheels, Powertrain, Unclassified - unlimitedSAE Driving Cycles, Transmissions, Inverters, Star Category 85Electronic-Commutation. DOE Category UC-96
19. Security Classif. (of this report) 20. Security Classif, (of this page) 21, No. of Pages 22, Price'
Unclassified Unclassified 239
' For sale by the National Technical Information Service, Springfield, Virginia 22161
NASA-C-168 (Rev, 10-7S)229
4
![Marginales [notice]](https://img.dokumen.tips/doc/110x75/6332429b4e01430403009661/marginales-notice.jpg)
