Spring Final Design Report.doc - NeoOffice Writer

8/8/2019 Spring Final Design Report.doc - NeoOffice Writer

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EML4930: Senior Design 1

Electric Motorcycle Design

Date Due: April 15th 2010Date Submitted: April 15th 2010

Group Members:

Mike FranckMichael Grgas

Ryan Thor


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Table of Contents

Executive Summary.................................................................................4Introduction..............................................................................................5

Problem Definition.............................................................................5

Background........................................................................................5Electric Vehicle Components...................................................................6

Electric Motors...................................................................................6Battery Types.....................................................................................8Charger...............................................................................................9Motor Controller................................................................................9

Concept Generation and Selection...........................................................10Concept Development........................................................................10Concept A..........................................................................................11Concept B...........................................................................................12Concept C...........................................................................................14

Concept D..........................................................................................15Early Concept Cost Breakdown.........................................................17Decision Matrix.................................................................................17

2-D Modeling and Analysis.....................................................................183-D Modeling and Analysis.....................................................................20Component Selection...............................................................................23Electric Drive Wiring...............................................................................25Concept Selection and Final Design........................................................26

Prototype............................................................................................29Cost Analysis...........................................................................................30Environmental Concerns..........................................................................31

Conclusion...............................................................................................33Future Plans.............................................................................................33Works Cited..............................................................................................36

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Table of Figures

Electric Motor Diagram...........................................................................8Concept A, Lead-acid Battery Configuration 1.......................................11Concept B: Lead-acid Battery Configuration 2.......................................13Concept C: Lead-acid Battery Configuration 3.......................................14Concept D: Lithium Polymer battery configuration, larger frame...........162-D Vehicle Analysis...............................................................................18Compound Gear Train.............................................................................20Vehicle Frame..........................................................................................20Forward frame subassembly....................................................................21Motor mount and belt assembly mount...................................................22Rear frame subassembly..........................................................................22Etek-R Brushed Permanent Magnet Motor..............................................23Alltrax motor Controller..........................................................................23Soneil Continuous Amperage Battery Charger 6A, 48 V........................24Marathon Deep Cycle Sealed Lead Acid Battery 12 V, 35 A-hr.............25

48 V Battery Wiring Diagram..................................................................25Electric Drive Wiring Diagram................................................................26Final Design.............................................................................................27Charger/Controller Diagram....................................................................27Motor mount and belt assembly mount...................................................28Rear Battery Mount..................................................................................28Prototype Final Design............................................................................29

Appendices

Appendix A: Mechanical Drawings.........................................................36Appendix B: Calculations........................................................................56Appendix C: Sponsorship Packet.............................................................61

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Executive Summary

The Electric Motorcycle Design projects goal is to produce a low budget, efficient means

of two wheeled transportation. With the help of technical sponsor Bruce Thigpen of

Eminent Technology, all design goals were met. At the onset of the project, the team had

in their possession a small Yamaha petrol dirt bike with which to convert to electric drive,

but was in search of a larger chassis to better accommodate the large battery pack. A

larger Honda chassis was located at the end of the semester.

Various forms of analysis were performed the team took into account theories from

Dynamic System's II when calculating the necessary power the vehicle would need. Gear

design theory was implemented from Mechanical Systems II. From The Finite Element

Method, ProEngineer Mechanicas modeling software was utilized to quantify the loads

placed on the chassis. The program was very helpful in determining if any strengthening

of the frame would be necessary; it also reduced the time that would have been spent on

numerical analysis.

The team chose a 48 volt battery system powering a brushed DC motor capable of

delivering up to 15 horsepower. For motor control, a popular unit was chosen based on its

numerous power control capabilities and familiar software. Charging is handled by a 48

volt, continuous amperage charger. Theoretical calculations have yielded an ideal range

of 39 miles, a max speed of 44 miles per hour as well as recharge time of 5.8 hours.

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Introduction

In the United States alone, nearly twenty tons of carbon dioxide from motor vehicles is

emitted per capita every year. These numbers are growing, sweeping changes must be

made to curb harmful greenhouse gas emission and mans dependence on fossil fuels.

Though in existence for over a century, electric vehicles have lately risen in popularity

due to the rising cost of gasoline. They offer a drastic reduction in overall energy

consumption as opposed to traditional internal combustion engine propulsion. This

project deals with the design and construction of one such EV, an electric motorcycle.

Electric motorcycles are a viable alternative to ICE motorcycles. They offer comparable

overall weight, and with a sufficient power supply, performance as well. The following

will present the teams overall analysis for the project.

Problem Definition

The team must design and fabricate an electric motorcycle within a specified budget.

Project goals include a minimum range for the vehicle of at least five miles, a top speed

of 25 miles per hour and a recharge time for the batteries of less than eight hours. A

budget of 1500 dollars was allotted to the build. Secondary objectives include

weatherproofing the motorcycle as well as providing adequate lighting and

instrumentation.

Background

In recent years, the reduction of human induced environmental impact has been at the

forefront of new innovation. Carbon emissions have come under great scrutiny as a major

contributing factor of climate change. Internal combustion vehicles account for roughly

28% of green house gasses emitting twenty tons of carbon dioxide per capita each year in

the United States alone.1 A new approach to transportation is needed to offset these

troubling numbers and foster a new attitude for the advancement of our culture within the

restraints of our environment and level of comfort.

One proposed solution comes with the development of fully electric vehicles. EVs are

propelled by an electric motor that draws its power from chemical energy storage via a

battery pack. The utilization of electric vehicles yields both advantages and

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disadvantages. Advantages include: increased energy efficiency, and decreased pollution

in the form of both emissions and noise. Whereas the advantages of an electric vehicle

can be categorized by attributes pertaining to energy consumption, its disadvantages can

be attributed to performance and cost. The main hurdle that EV's face is the task of

efficiently storing the energy required to meet the average drivers performance needs,

i.e. battery size/storage capacity. There exists a delicate balance between an efficient EV

and one that is not. Vehicle weight is that dominant limiting factor. An efficient

aerodynamic vehicle profile and a low coefficient of rolling resistance can be achieved

with relative ease. A battery pack that marries a long vehicle range and relative light

weight is much more difficult to achieve. Though advances have been made in the

production of smaller, light weight batteries (lithium-ion, lithium polymer), their high

cost limits their use in many applications. Often, cheaper lead-acid batteries are

implemented, but their greater weight will drastically reduce driving range.

The effects of a heavy battery stack can be countered by a reduction in vehicle size. By

reducing the size of the vehicle, energy requirements drop dramatically. A low

aerodynamic profile, lightweight chassis and low rolling resistance from thin tires will

result in improved performance. These trade-offs render a motorcycle a prime candidate

for an EV application.

Electric Vehicle Components

Electric motors

Electric motors are machines that convert electrical power into mechanical power. They

use magnets and a set of conductors to convert this electrical power input into rotational

motion. Electric motors can be classified in one of two categories based on the type of

power supplies, namely alternating current (AC) or direct current (DC) motors. They all

however have some basic characteristics in common. Theyre made up of very few parts

including a stator or frame, a rotor or the rotating shaft, and some kind of auxiliary

equipment like a brush/commuter for a DC motor and a starting circuit for an AC motor.

AC Motors

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There are two basic type of AC motors, induction and synchronous. Induction motors are

simple in design, allowing for easy construction. They are relatively inexpensive and

require little maintenance and compared to DC brushed-motors, have a longer life

expectancy. The synchronous motor runs at a fixed speed independent of the applied

load. All AC motors fall within two classifications, single or three phase. Single phase

motors have a limited power range, usually up to a few horsepower and in the induction

type only. Three phase motors offer higher power output and are usually only available as

synchronous machines. Other variations of AC motors exist; the most notable is the ac-

commutator motor or the universal motor which can be found in many home applications

like vacuum cleaners.

DC Motors

DC motors are used in applications where precise speed control is desired. They are

classified based on the method by which the armature is connected to the field windings

or current carrying coils around a field magnet. The armature is the rotating part of a

brush type (DC) motor. They can be classified as series, shunt, compound or permanent

magnet motors. The following terms are necessary when discussing DC motor

characteristics; load, torque, speed, counter-electromotive force (CEMF), and armature

current. A motors operational characteristics depend greatly on the mechanical load

applied to the shaft. It should be noted that a motors speed tends to decrease as the

applied load is increased. As the shaft speed decreases, the voltage (due to CEMF) within

the conductors decreases. The voltage or CEMF depends on the number of rotating

conductors and the speed of rotation, hence the lower the speed the lower the necessary

voltage. Since the CEMF is in opposition to the supplied voltage, the actual working

voltage will increase as CEMF increases. This increase in working voltage means that

more current will flow through the armature windings. This increase in armature current

will increase the torque produced by the motor. In contrast, if shaft speed is increased,

CEMF will increase. Therefore, working voltage will decrease along with current through

the windings. This will lead to less torque being produced by the motor. Speed control is

the most attractive characteristic of DC motors. The speed can be controlled, simply by

varying the voltage supplied to the motor.

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Each type of DC motor will display unique characteristics. Permanent magnet motors are

used for low torque applications. Compared to other DC motors permanent magnet

motors have low operational cost. The direction of rotation can be reversed by switching

the positive and negative power leads. Series wound motors are used in high torque

applications where heavy loads must be moved and speed regulation isnt important, they

are widely used as automotive starters. Shunt motors are used in applications above 5

horsepower. They run at virtually constant speed regardless of the applied load. They can

be found in machine shop lathes. The compound motor takes advantage of the desirable

characteristics of shunt and series motors. They boast the high torque capabilities of

series motors and the constant and controllable speed characteristics of shunt motors.

They can be found in air compressors, conveyors, and elevators.

Figure 1: Electric Motor Diagram

Battery Types

The heart of the electric vehicle is the battery system and is probably the most expensive

component. Our battery selection will play a major role in whether we are able to

optimize the motorcycle to the customers specifications under budget. Our battery

options are: lead acid, nickel cadmium, nickel metal hydride, lithium ion. Below we will

discuss some of the advantages and disadvantages of each battery type.

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A lead-acid battery (SLA) is versatile, easy to charge, and cheap but it has low energy

density and is heavy. Generally they can only store 25 watt-hours per kilogram compared

to a lithium-ion battery which can store about 150 watt-hours per 1 kilogram.

Nickel-Cadmium (NiCad) battery is long lasting in terms of a charge/discharge cycle. It

boosts a better power to weight ratio than (SLA). However, they are more expensive than

(SLA).

Nickel-Metal Hydride (NiMH) batteries are a compromise between NiCad and the

Lithium-Ion (Li-Ion) batteries. Though they have a longer single charge life than NiCad

they have a shorter total lifespan.

Lithium-Ion batteries offer a very high energy density as compared to the other options. A

typical lithium-ion battery can store 150 watt-hours of electricity in 1 kilogram of battery.

Heat causes the battery to degrade at a faster rate than they normally would. An on-board

battery management system must be installed to ensure a long and healthy battery life.

Initially, they are quite expensive but their 2000 charge lifespan means they will last

approximately five times longer than comparable SLA batteries.

Charger

The team will use a simple light battery charger capable of outputting 48 volts at six

continuous amps to the battery pack. The pack should recharge in 5.83 hours.

Motor Controller

Operating a motor under perfect and economical control at a desired speed will require

the implementation of some type of variable speed drive system. Variable speed drive

applications are dominated by DC drives or controllers because of their low cost,

reliability and simple controls. During startup, DC motors are limited by a safe maximum

current to prevent the commutators from sparking. If the motor is started with a full

supply voltage, a very high current will flow which may damage the motor. A controller

can be use to control the voltage and current supplied to the system. In addition to

damage control, controllers can be used to manage other aspects of the system. For

example, regenerative braking, and dynamic braking control. Induction motor controllers

are cheap, rugged and can be operated in extreme environments. They can be run at high

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speeds, voltage, and power ratings. Unfortunately, the cost of an induction motor is much

higher than that of a DC motor.

DC drives utilize a solid-state adjustable frequency inverter to adjust the frequency and

voltage in order to vary the speed of an otherwise, conventional fixed speed AC motor.

This is achieved through Pulse-Width Modulation (PWM) of the drive output to the

motors. In order to maintain a constant torque, the voltage and frequency are maintained

at a constant relationship at any motor speed. This is known as the volts per hertz ratio.

AC drives utilize a converter to transform AC current into DC current. DC motors are

designed for adjustable speed operation. Therefore, controller simply regulates the

voltage fed to motor to change the speed.

Concept Generation and Selection

Concept Development

The design process for any product begins with concept development. It is important for

a design team to bounce around as many ideas as possible in order to arrive at the

optimum design. There are a number of key parameters that must be taken into

consideration when developing concepts for a motorcycle build. With a budget of $1500,

design feasibility is of upmost importance. Without the cushion of supplementary

funding, designs are limited to retrofitting components onto the small motorcycle frame

currently owned by the team, as well as the use of lead acid batteries as the source of

energy storage. However, because the team has been eagerly seeking sponsorship,

concepts have been developed that incorporate lithium iron phosphate (LiFePo4) batteries

and a larger frame. The use of a bigger frame will increase the riders comfort, while

LiFePo4 batteries will increase performance through reduction in weight and vastly

increase the batteries overall life. Motor placement should also be carefully considered.

When designing a direct, chain drive motorcycle, the motor should be placed as close to

the pivot point of the rear suspension as possible so as to reduce variations in chain

tension as the suspension is compressed. Other factors that influenced design concepts

include rider comfort, overall center of gravity, and heat generation from the various

components. Components to be mounted to the motorcycles frame are as follows: Motor,

Motor Mount and Drive Train, Motor Controller, Batteries, and Battery Charger.

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Concept A

Ideally, the motorcycle frame would be large enough to easily accommodate the

peripherals and components necessary to have a functioning electric motorcycle. Concept

A, reflects one possible configuration with a larger frame. The motor is affixed to a

motor-mount on the center brace of the cage. Four 48 volt, 35 amp-hour lead acid

batteries are secured to the front beam, and remain open to the air to allow forced

convective cooling. In order to maintain a low center of gravity, the batteries are

positioned close to the motor without causing interference. The motor controller and the

charger are bolted to the center divide on either side of the frame

Figure 2: Concept A, Lead-acid Battery Configuration 1

Analysis

Cost:

A larger, replacement frame and chassis will raise the cost of the build and will add

weight to the motorcycle. Though heavier and more expensive, a larger frame will

conveniently accommodate the components required to achieve our design specifications.

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Performance:

This concept will meet the requirements of the customer. The power supply and motor

will combine to reach the desired top speed and range. When comparing this concepts

performance to a concept that utilized the smaller frame, added weight from the larger

frame will cause the performance of the bike to suffer. However, due to the larger amount

of space available, components can be mounted closer to the center line of the bike

therefore slightly reducing its frontal area. Limiting the frontal area will result in a

reduction of wind resistance and an increase in performance. In comparison, the

increased weight reduces performance more than the reduction in frontal area increases

performance. The result is a net performance decrease.

Comfort:

Fabrication becomes easier with a bigger frame and rider comfort would arguably be

better. A larger frame affords more flexibility in positioning and rearranging certain

components to suit the rider, thus improving the comfort of the ride.

Safety:

Rider safety is increased with the incorporation of a larger frame. Components can be

placed so as to lower the bikes center of gravity thereby improving its handling. A bigger

frame also makes it easier to facilitate the many features required to make the bike street

legal.

Concept B

The following concept utilizes the existing frame and chassis. Four sealed lead acid

batteries will be placed in battery trays mounted to the frame. Two will be placed over the

rear tire similar to saddle bags on a cruiser type motorcycle. The other two will be placed

behind the fork in front of the riders knees and mounted on the down pipe of the frame.

The motor mount is placed so as to position the motor shaft close to the rear suspensions

pivot point. Charger and motor controller are to be mounted in a box inside of the

motorcycles seat. The charger is to be placed furthest back facing the rear so as to

maximize accessibility.

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Figure 3: Concept B: Lead-acid Battery Configuration 2

Analysis

Cost:

This configuration is to be used as an option if supplementary funding is not received for

the purchase of a bigger frame and a more efficient battery stack. The existing frame is

utilized as well as the least expensive battery option. As a result, Concept B is the most

cost effective.

Performance:

Concept B also meets the needs of the customer. Concepts A, B and C each contain the

identical components. However, Concept A weighs more due to the use of a larger frame.

Concepts B and C are equal in weight and both out perform A. The frontal area is slightly

increased with this design, but to reiterate, the reduction in weight has a bigger impact in

the overall performance.

Comfort:

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The battery charger and motor controller are placed beneath the riders seat. This will

raise the rider by approximately 4 inches and as a result, decrease the riders comfort. The

small frame is also not very comfortable for a full grown adult to ride for an extended

period of time.

Safety:

Due to lack of available space within the frame, components must be placed based on

where they fit rather than where they would effectively lower the center of gravity.

Because of this, handling, as well as safety is decreased. This reduction in available space

also produces difficulties in making the design street legal.

Concept C

Concept C is exactly the same as Concept B with the exception of where the two front

lead acid batteries are mounted. Instead of being mounted to the frames down pipe, the

batteries are mounted to the support member that runs parallel to the ground, and hang

from either side of it. Figure 3 illustrates this variation in the front battery mount location.

All other components and mounting locations resemble Concept B.

Figure 4: Concept C: Lead-acid Battery Configuration 3

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Analysis

Cost:

Cost is equal to that of Concept B. Without the additional cost of purchasing a new frame

or more expensive batteries, Concept B and C rank as least expensive and fall within our

current budget.

Performance:

This configuration will meet the customers needs. Its weight is equal to that of Concept

B. Due to the front batteries being mounted higher on the frame, the bikes center of

gravity is raised and consequently, its handling will suffer.

Comfort:

As in Concept B, the battery charger and motor controller is located under the seat. The

riders sitting position will therefore be elevated resulting in a reduction of comfort. Thealternate location for the front two batteries may render it difficult for the rider to situate

his or her legs comfortably. This concept proves least comfortable for the rider.

Safety:

The overall safety of this designs configuration also ranks last. Along with the difficulty

of adding the required components necessary to make the bike legal on such a small

frame, the higher center of gravity makes it top heavy and reduces its ease of handling.

Concept D

This design concept design is similar to the pervious concepts with the exception of a few

minor modifications to the components of the bike. The larger motorcycle frame will be

used to house the components. The battery chargers location is changed from under the

operators seat to the underside of the frames top support member. Also, the lead acid

batteries previously selected to power the bike will be removed and lithium polymer

batteries will take their place. Motor, motor controller, and battery charger are the same

as in concepts A, B, and C.

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Figure 5: Lithium Polymer battery configuration, larger frame

Analysis

Cost:

Due to a few modifications to the pervious concepts, the total cost of the bike will

increase. The lithium polymer batteries used for this concepts are 3.2 volts each and cost

$3.50 per Amp. Under ideal conditions a 35Amp/hr battery set up would make a very

powerful electric vehicle. The price per battery will be roughly $122.50. Also the bike

requires 48 volts to the power the motor, therefore 15 batteries will be required to attain

48 volts. The total price of the battery pack will be approximately $1837.50. Another

design suggestion for the batteries to reduce the price is to lower the amperage from

35Amp/hr to 20Amp/hr. This will decrease the price from $122.50 to $70.00 per battery

and the total cost of the battery pack will decrease from $1837.50 to 1050.50. The larger

frame will have to be bought and will therefore also increase cost. All other components

are the same as in concepts A, B and C

Performance:

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It was estimated that the larger frame will add an extra 20-40 lbs over the smaller frame.

However, the lithium polymer batteries are much smaller that the SLA packs. The total

weight addition from batteries will decrease from 104 lbs to 49.5 lbs. The lighter and

lower placed lithium polymer batteries will increase performance and aid in handling.

Comfort:

With the addition of a larger frame and given that all the major components of the bike

will be tucked away between the riders legs, ride comfort will be maximized if this

design is utilized.

Safety:

As with Concept A, the larger frame allows for the components to be placed lower on the

frame increasing handling. Along with improvements in handling, a larger frame eases

the process of making the motorcycle street legal.

Early Concept Cost Breakdown

Concept Motor Controller Batteries Charger Frame Total

A 450.00 325.00 295.80 159.00 200.00 $1,429.80

B&C 450.00 325.00 295.80 159.00 Free $1,229.80

D 450.00 325.00 1,837.50 159.00 200.00 $2,971.50

Decision Matrix

The decision matrix below supports the groups intuition that Concept D is the more

desirable design. It will exceed all the customers needs and performance requirements.

Unfortunately, this design is only possible at a high cost premium. The cost of the

lithium-ion battery pack alone exceeds the groups current budget. With this in mind the

second best option, Concept B will achieve the projects goals. It will meet the 25mph

minimum top speed, the 5 mile minimum range and still be under budget.

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Concepts

A B C D

SpecificationsSpecificatio

n Weight

Ratin

g(1-5)

Weighted score

Rating

Weightedscore

Rating

Weightedscore

Rating

Weightedscore

Configurability 22% 4.0 0.9 1.0 0.2 1.0 0.2 4.0 0.9

Weight 33% 1.0 0.3 2.0 0.7 2.0 0.7 4.0 1.3

Cost 11% 2.0 0.2 4.0 0.4 4.0 0.4 1.0 0.1

Comfort 22% 4.0 0.9 3.0 0.7 2.0 0.4 4.0 0.9

Availability 11% 1.0 0.1 5.0 0.6 5.0 0.6 1.0 0.1

Score 2.44 2.56 2.33 3.33

selection No Yes No Yes*

2-D Modeling and Analysis

Figure 6: 2-D Vehicle Analysis

Upon receiving the customers needs, it was necessary to understand the physics of the

problem in order to deliver the proper engineering specifications. A simple free body

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diagram, displayed above, was used to illustrate the forces that act on the vehicle. Some

assumptions were necessary in order to solve the problem. These assumptions can be

found along with the relating calculations in Appendix B. Using the defining equations

the average power needed to cruise at an average speed was calculated.* Next, the

amount of torque needed to accelerate the vehicle from rest to the specified speed was

determined.* The results were reviewed by the Mr. Bruce Thigpen and Dr. Patrick Hollis.

Armed with theses results, it was then necessary to research motor options that met these

minimum requirements.

*Appendix B

Drive Train

The task of a motorcycles drive train is to convert torque and angular velocity from the

motor into vehicle motion. The drive train should be configured as to maximize the

vehicles efficiency, and be able to overcome hills. When comparing the drive train of an

internal combustion vehicle to an electric vehicle, the differences are vast. This is due to

their inherently different characteristics. A motorcycle that is powered by an internal

combustion engine requires a clutch, transmission, and torque convertor in order to

accelerate from standstill. This is due to the fact that an IC engine produces nearly

negative torque until some speed is reached. On the contrary, an electric motor produces

high torque at zero speed and therefore eliminates the need for any extra mechanical

components. Consequently, an electric motor can be attached directly to a motorcycles

drive wheel. Many electric motorcycles currently in production use a direct chain drive

design. Although this method efficiently delivers power to the rear drive wheel, this

generates a substantial radial load on the motor shaft, therefore creating a torque on the

motor. As a result, an extremely robust motor mount would be required so as to prevent

the motor from twisting within the frame. A small modification in this design was made

in order to alleviate some of the torque. The use of a proprietary belt drive connected to a

direct chain drive has reduced the torque on the motor by 40%. A belt drive was chosen

for the proprietary drive in order to minimize noise. A chain is used for the second drive

in order to make use of the existing sprocket, currently attached to the rear wheel.

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Figure 7: Compound Gear Train

3-D Modeling and Analysis

Below is a model of the vehicle frame. ProEngineers Mechanica was used to analyze the

various loads on the frame. This was carried out due to concerns over excess weight from

the battery pack that may have endangered the frames structural rigidity. The team

analyzed loading from the forward and rear battery packs, as well as those from the rider.

Figure 8: Vehicle Frame

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The frame is a welded chro-moly steel unit with a wall thickness of 0.125 inches, the

chro-moly has a max yield stress of 52 kpsi. The frame was dissected into three major

components so as to simplify analysis Mechanicas analysis. The following analyzes the

forward battery box section of the frame. A distributed load of 52 pounds was placed on

the frame down pipe, while the part was constrained at the front fork and accompanying

frame connections. Max component yielding was 1.56 kpsi, well below the materials

limit.

Figure 9: Forward frame subassembly

Below is a cutaway of the motor mount that the team has designed, the protruding pin is

the main mounting point for the belt-gear drive assembly. A 79 pound radial load was

analyzed on the pin, Mechanica found it to be 2.288 kpsi. This value is also well below

the materials limit.

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Component Selection

A motor capable of propelling the vehicle to the desired speeds was necessary and was

found in the Etek-R brushed DC motor. Capable of producing eight continuous

horsepower as well as fifteen for short periods of time, the motor is ideal for this

application. Only eight inches in diameter and six inches deep, its small size is ideal for

the small frame. Lastly, weighing only 26 pounds, it weighs much less than the internal

combustion unit it is replacing.

Figure 12: Etek-R Brushed Permanent Magnet Motor

The motor controller below is a popular unit amongst EV builders, it is capable of

achieving a motor speed of 3700 rpm at 48 Volts. The unit is capable of controlling max

current, max speed, hi and lo voltage cut off, acceleration and deceleration rates as well

as custom throttle settings. Lastly, its user friendly free open software allows the team toeasily modify the controllers settings without needing a wealth of programming

knowledge.

Figure 13: Alltrax motor Controller

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The 48 Volt, 6 A-hr continuous amperage charger pictured in figure 16 will recharge the

battery pack in 5.8 hours. Its low cost, small overall dimensions and lightweight package

made it an obvious choice.

Figure 14: Soneil Continuous Amperage Battery Charger 6A, 48 V

Battery selection is based on a number of factors including (in order of importance)

voltage, current rating, cost, weight, and geometry. From theoretical calculations it was

determined that in order to meet the customers expectations, a battery of at least 48 volts

and 32 amp-hours will be required to provide the proper power and current to the motor.

Due to budget limitations, lead acid batteries are the only realistic option for a power

source. Though heavy and bulky, they are capable of providing the performance

necessary to meet the objectives. Ideally, a smaller, more efficient power source such as

nickel cadmium, nickel metal hydride, or lithium-ion batteries would have been selected,

but the cost of doing so would have put the project well over budget. To reduce charge

time and decrease total weight, a 35 amp-hour rated battery was selected yielding a

charge time of 5.3 hours and weight of 104lbs. The battery configuration chosen

consumes a net volume of 266 cubic inches.

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Figure 15: Marathon Deep Cycle Sealed Lead Acid Battery 12 V, 35 A-hr

Figure 18 illustrates a simple diagram of the wiring scheme the team will use, the four, 12

Volt SLA batteries will be wired in series so as to produce a total of 48 available volts.

Figure 16: 48 V Battery Wiring Diagram

Electric Drive Wiring Diagram

The following illustrates the necessary connections between the drive components.

When charging, the battery charger connects to a standard 120 V wall outlet. From the

battery pack, one fused lead passes through the DC contactor as well as one to the Alltrax

motor controller. The DC Contactor, aka solenoid, is used to connect and disconnect mainbattery buss power. The turning of the ignition on an EV flips this switch to allow power

to ultimately flow to the motor. Due to its ability to cut power quickly and easily in an

emergency situation, a DC contactors inclusion in an EV build is absolutely essential.

From the motor controller, two leads terminate at the DC motor. Motor rotation can be

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easily changed by swapping the leads on the motor. The motor will need to turn counter-

clockwise for this application.

The PWM (Pulse Width Modulation) throttle that will be used differs from a

conventional proportional voltage throttle. The PWM signal allows the motor to receivefull available voltage very quickly but for a short period of time. The slow rise and decay

in motor speed that comes with a proportional voltage throttle is eliminated producing

predictable results. This is very important when the life of the rider is in danger and a

quick reaction in necessary.

Figure 17: Electric Drive Wiring Diagram

Concept Selection and Final Design

Concept B was selected for the project. Throughout the semester, the team redesigned

Concept B adding lighter battery boxes and a more efficient means for mounting the

motor controller and battery charger. A heat sink was added below the charger and

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controller to aid in component cooling. A stronger motor mount was designed to better

fix the motor and gear train to. The final concept is shown below.

Figure 18: Final Design

Figure 19: Charger/Controller Diagram

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The motor mount was strengthened to include the addition of the gear train. Ventilation

was increased so as to aid in passive cooling. A small fan (not pictured) will be installed

on the rear of the motor as a means of active cooling.

Figure 20: Motor Mount and Gear Train

The rear battery mount was designed to accommodate both lightweight and full grown

riders. The box can be lowered two inches for a lighter rider. The lower center of gravity

afforded by the change will make for better handling and increased rider confidence. For

heavier riders, the cages can be raised to allow for full suspension movement.

Figure 21: Rear Battery Mount

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Prototype

Figure 22: Prototype Final Design

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Cost Analysis

A cost analysis is illustrated below, the project is under budget. Due to the build being

nearly over budget, the team decided to craft a sponsorship packet. Attached in Appendix

C, the team hopes it will bring in some additional funding. It is being circulated amongst

the suppliers from whom the team will be purchasing components.

Item Vendor Description QuantityUnit

PriceShipping Subtotal

Chassis N/A 50 cc Pit Bike 1 0.00 0.00 0.00

MotorElectric

MotorsportBrushed DC 1 450.00 34.65 484.65

ControllerElectric

Motorsport

Alltrax PWM 1 325.00 9.52 334.52

Battery

Pack

Battery

Source12 V, 35 Ah 4 75.95 0.00 303.80

ChargerBattery

Source48 V, 6 Ah 1 159.00 0.00 159.00

Rear TireTallahassee

MotorsportsRadial Tire 1 70.95 0.00 70.95

Front TireTallahassee

MotorsportsRadial Tire 1 43.58 0.00 43.58

DC

Converter

Electric

Motorsport

Allows for 12 V

Accessories

1 25.00 4.95 29.95

Aluminum

6061

Eminent

Technology

Aluminum

Stock1 0.00 0.00 0.00

Steel Angle

Iron

Eminent

TechnologySteel Stock 1 0.00 0.00 0.00

Throttle and

Handgrip

Electric

Motorsport

0-5K

Potentiometer1 0.00 0.00 0.00

Pre-charge

Resistor

Eminent

Technology

Regulates current

flow1 0.00 0.00 0.00

Suppression

Diode

Eminent

Technology

Regulates

Voltage

1 0.00 0.00 0.00

TOTAL $1426.45

Environmental Concerns

The nations need for transporting freight and people is steadily growing year in and year

out. As a result, the transportation sector is becoming increasingly linked to

environmental problems. Dr. Jean-Paul Rodrigue and Dr. Claude Comtois, of the Dept. of

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Global Studies and & Geography wrote in an article, It has reached a point where

transportation activities are a dominant factor behind the emission of most pollutants and

thus their impacts on the environment. Several millions of tons of harmful greenhouse

gases are released into the atmosphere each year due to transportation activities. Though

theres ongoing debate regarding the extent the emissions are linked to climate change,

its clear that the burning of hydrocarbons through the use of the internal combustion

engine negatively affects the air quality, and noise levels.

Air pollution accumulating from vehicle emissions is damaging to human health. These

toxic pollutants have been linked to respiratory, neurological, cardiovascular diseases,

and even cancer.

Its believed that the rise in the noise levels has an adverse affect on the hearing organ

which may in turn affect ones quality of life. Studies support that noise from the

movement of trains, planes, cars and other types of vehicles can increase ones risk for

cardiovascular disease.

Water quality has also been adversely affected due to transport activities. Fuel, chemical

and other hazardous particulates improperly discarded from cars and trucks will drain

into and contaminating water supplies. According to the EPA, 52 million cars where

newly registered in 2007 alone. An increase in the number of vehicles on the road will

increase the demand of foreign oil. Oil spills from oil cargo vessel accidents are one of

the most serious problems of pollution from maritime transport activities.

The electric vehicle (EV) has the potential to dramatically reduce the environmental

impact of the transportation industry. Though EVs produce no direct air pollution, they

are certainly not zero-emission vehicles. The electricity that is used to charge the batteries

of an EV may still be produced in environmentally unfriendly power plants, like coal

plants which generate over 50 percent of the U.S. power. Its important to point out that it

may be easier to control the emission out of power plants, than that of millions of

vehicles. In addition to reducing emissions, production EVs are arguably less straining

on Earths resources. EV motors are generally more compact, requiring less material than

a comparable internal combustion engine. Until the means to store the necessary energy

catches up to that of fossil fuels, the EV will not become a staple of the roadways.

Though it needs an adverse amount of storage for the battery pack, some argue that the

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sparse total material used in an electric motor is a tradeoff between those necessary for an

internal combustion engine.

The batteries used to power EVs pose some potential environmental and health risks.

Lead is highly toxic and the EPA has imposed several regulations to reduce humans

exposure to the substance. According to the EPA 1.3 million metric tons are consumed in

the US each year and 79 % of which can be found in lead acid batteries. Short-term

exposure to high levels of lead can cause vomiting, diarrhea, convulsions, coma or even

death. Regular exposure to even a very small amount of lead can be harmful, especially

to infants and young children. Lead can also damage the brain and nervous system. Some

other symptoms are: appetite loss, abdominal pain, constipation, fatigue, sleeplessness,

irritability, and headaches.

Lithium-ion batteries offer the benefit of having high energy density. This means that the

battery can store large amounts of energy over a small volume. Made from lithium and

carbon, they are generally much lighter than other types of batteries. Lithium is a highly

reactive, equating to a chance that the battery pack may burst into flames when exposed

to thermal runaway. All packs are mated to a battery management system, making fire

uncommon. According to an article on howstuffworks.com, 3 out of 1 million batteries

have been reported to fail in such a way.

Recyclables / Hazardous Materials

Fortunately, the EPA also reports that more than 97 percent of battery lead is recycle.

They can be broken down and the plastic can be recycled to make new battery cases. The

old acid can be neutralized and released in the sewer system or it can be reclaimed and

reused in new batteries. The acid can also be treated and used as agricultural fertilizer,

lastly it can be converted to gypsum for use in the production of cement.

Finally, in converting the internal combustion motorcycle to an electric motorcycle, its

inevitable that the IC engine, exhaust system along with some other misc parts which will

become unnecessary in the operation of the electric motorcycle, will need to be sold to a

willing proprietor or scrapped. If these parts are not properly disposed, they will end up

in a landfill.

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Conclusion

After taking into account the performance characteristics that need to be reached, the

team performed a quantitative analysis and made an informed decision when selecting its

design concept. That concept was constantly reviewed and redesigned throughout the

semester, and has been described in detail above. The electric motorcycle will be

powered by a 48 volt battery pack, mated to a variable motor controller and powered by a

4.5 kW DC motor. Theoretical top speed is 46 mph with a 170 lb rider.* Theoretical

vehicle range was calculated to be 71.2 miles.* These numbers were calculated at a

cruising speed of 15 mph in an ideal riding environment (flat terrain, zero wind, 25 C

ambient air temperature). Stop and go riding as well as adverse terrain will bring the

numbers down significantly. Real world range and top speed will be analyzed for the

vehicle during shakedown tests in the next semester. Under budget and on time, the

motorcycle is on track for completion by December of 2010.

*Appendix B

Future Plans: Fabrication/Testing

In the closing weeks of the semester, a suitable replacement chassis was donated to the

team by Kevin Malfa. The Honda chassis is ideal for the teams application. It is a small

commuter motorcycle and is lightweight and devoid of superfluous accessories that

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would encumber the build. The team will redesign the motor mount and battery boxes but

will still be using all the selected components. Fabrication will begin in late August;

component purchasing will begin then as well. The team is also researching battery

chargers that can utilize a 240 VAC wall outlet, the increased voltage will decrease

recharge time.

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Acknowledgements

Bruce Thigpen

Dr. Waryoba

Dr. Shih

Kevin Malfa

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Works Cited

1. Advanced Battery Systems, LLC . 8 February 2010

http://www.advancedbattery.com/

2. BatteryMart.com . 8 February 2010 .

3. Ehsani, Mehrdad, Yimin Gao, Sebastien E. Gay, Ali Emadi. Modern Electric,

Hybrid Electric, and Fuel Cell Vehicles. Boca Raton: CRC Press, 2005

4. Electric motor superstore 8 February 2010 www.emotorstore.com/

5. Electric Motor Handbook, Mcgraw Hill Handbooks, H. Wayne Beaty and James L

Kirtley, Jr. copyright 1998, The McGraw Hill Companies, Inc. New York, NY

10011.

6. Emotors Online.8 February 2010 http://www.e-motorsonline.com

7. Neatorama.com 21 February 2010


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Appendix B: Calculations

The following illustrates the necessary the necessary power from the motor to propel the

motorcycle to 25 mph.

From Product Specification Report:

The equation takes into account the vehicle mass factor, which is estimated at 1.0425 [1].

Mass of the motorcycle alone is approximately 105 kg, and rider weight is 80 kg.

Combined, these make up total motorcycle weight Mv. An acceptable acceleration time

(ta) of 4 seconds was chosen to reach the top speed. Final velocity (V f) is 25 mph (11.17

m/s), while initial velocity (Vb) is 0 mph. For motorcycles with properly inflated road

tires, the coefficient of rolling resistance (fr) is approximately 0.0055. Air density (ra) is

1.2 kg/m3 for standard atmospheric conditions. The drag coefficient (Cd) for the

motorcycle was estimated at 0.95. Frontal area of the motorcycle (Af) was measured. A

61 tall rider, seated upright on the motorcycle displaces a frontal area of 0.46 m^2.

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Later Calculations:

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Mechanical power ( totalP ) required for motor at cruising speed:

32.1 mkg

a Density of air

0055.0rf Coefficient of rolling resistance

95.0dC Coefficient of dragkgM 37.172 Mass

smVc 71.6 Cruising Velocity

246.0 mAf Frontal Area

3

5. cfdadrag VACP

= 79.2 W Watts required to overcome dragMgFVP rcrolling = 62.4 W Watts required to overcome rolling resistance

rollingdragtotalPPP = 141.6 W Total mechanical power required

Total electrical power ( bP ) from batteries at cruising speed:

8.0m Motor efficiency

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rollingdragtotalPPP = 141.6 W Total mechanical power required

totalmb PP = 177 W Total electric power required

Yearly cost analysis:

hrkWC

T

$12.0 Tallahassee price per kilowatt hour

8.0c Charge efficiency

milehrkWE

m

009441.0 Kilowatt hours per mile

mileECC

mTm$0011. Cost per charge

milesMavg 8000 Miles per year in average Americans

commute

avgmy MCC = $9.06 Cost per year for average commuter

Range Analysis:

VV 24 Cruising voltageWPb 177 Total electric power required

AVPI b 38.7/ Cruising Amps

hrIAhrt 75.4/35 Runtime per chargemilestVR c 2.71 Miles per charge

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The below gear train reduces the radial load on the motor and gear shafts by 40%, from

132 lbf to 79 lbf.

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Appendix C: Sponsorship Packet

March 2010

Company Name

Company AddressCity, State Zip

FAMU-FSU College of Engineering Electric Motorcycle Concept for 2010 Senior

Design Team

> can play a vital role in the success of three future engineers byparticipating in our Senior Design Sponsorship Development Program. The team is currentlydeveloping a low cost electric motorcycle. The ultimate goal for the project is to build amotorcycle with comparable performance of a midsize gasoline motorcycle. This program isdesigned to help the team obtain a fuller understanding of the engineering topics and procedures

pertaining to our project, while giving our sponsors name recognition among engineering studentsand the larger university communities.

This program can benefit in many ways. As a sponsor, your company willhave direct advertising to over 2,300 students and 90 faculty members of the FAMU/FSU Collegeof Engineering. Also available to the team is direct advertisement on the FSU main websitewhich is trafficked by over 500,000 viewers monthly. will also be advertisedon our team website, at events, on posters around the school, and on the t-shirts of the teammembers. For your tax-deductible contributions, the students of FAMU/FSU Engineering willproudly display your logo on the motorcycle itself to show your support of Florida StateUniversity and Florida A & M University.

This Development Program will provide monetary funds and resources to the team, allowing usto build the best possible representation of our design work. If you have any questions aboutbecoming a sponsor of our Development Program, please contact me. I would be happy toexplain our project and goals in more detail and to discuss your participation in this yearsevents.Dont miss this opportunity to impact the current students of engineering and yourfuture employees from FSU and FAMU.

Sincerely,

Michael GrgasTeam leader

(954) 655 9197

Documents

Spring Final Design Report.doc - NeoOffice Writer