EV-EMCUEV-EMCUElectric Vehicle - Economy Electric Vehicle - Economy

Mode Control UnitMode Control Unit

Shauntice DiazChris Chadman

Vanessa Baltacioglu

Group 4

Goals & Objectives

•Extend range by implementing economy-mode•Minimize power usage by attenuating

acceleration to an optimum value•Use several microcontrollers to allow data

recording, vehicle safety, and to calculate optimum power usage

•Take in user’s inputs such as current, State of charge, RPMs, MPH, temperature, and acceleration

•USB storage or SD card •Intelligent driving system •DOT Approved

Specifications & Requirements

•To increase range by 5-10%•12V auxiliary power supply•144V vehicle power supply •7 electrical sensors •5v power supply for microcontrollers•Data recording for 90 minutes •C language

Overall Block Diagram

Physics • Relate Electric Power to Mechanical Power• Find Minimum Acceleration for Economy Mode• Minimize Electric Power Loss through Heat by Limiting Current /

Acceleration• Find Power Needed for Acceleration

Pin = VIin = 220.46v + 0.87v3 + vma + vmg*SIN(θ)

Pr Pa

• Current as a Function of Acceleration and VelocityI = [220.46v + 34.32v2 + 13,789v*sinθ + 1406va] / V

• Max Current ~ 350 A; Attenuate Potentiometer as % of I• Test Values

Physics

Physics•Peukert’s Law:

t = Time of DischargeH = Rated discharge Time (hrs)C = Rated Capacity @

Discharge Time tI = Discharge CurrentK = Peukert’s Constant

K

IH

CHt

*

Peukert's Law

0.00

1.00

2.00

3.00

4.00

5.00

6.00

7.00

8.00

9.00

10.00

0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 260 270

Amps

Ho

urs

Physics

•Internal Battery Resistance▫EV12A- AGM; Ri = 3.2mΩ

▫Full Power VI = 144V*350A = 50.4 kW

▫Power Loss @ 350A = 4.7 kW; 9.5%

▫Temperature Effects

Sensors • Speed

▫0 to 70 miles per hour

▫Pulse Width Modulation

• RPM▫0 to 5000

Revolutions Per Minute

▫Pulse Width Modulation

• Current▫ -500 to 500 Amps▫Analog

• State Of Charge▫10.5volts – 13. 2

Volts ( 0 to 100%)▫Analog

• Battery Temperature▫ -40 NC to 60 NC▫ Analog

• Potentiometer▫0-12Volts▫Analog

• Accelerometer▫± 2g’s (horizontal)▫Analog

Speed Sensor

•’94 Transmission, ’04 Vehicle•Electrical Sensor added PWM•Measured from Transmission or Rear Diff (ABS)

RPM sensor

•Measured from motor using Hall Effect•Recommend by NetGain •Operates under 12V(DC) power supply•2.2K integrated resistor •Pulse width modulated output 5.5 mA

Current sensor

•Hall Effect current sensor •From EV source recommended by NetGain •Series connection to 144V system•Measures the range of ±500 Amps•Output signal of 1.5 to 4.5 Volts•Linearly related

State of Charge

•PakTrakr 600EV •Measures current, SOC, and battery Temp•RS-232 output •Expensive

Accelerometer •Dimensions

Engineering • Had specs that met

the requirements•Simple design •±2g to the velocity

plane of the vehicle•Internal 3.3v

voltage regulator •Output in volts

[XOUT – (VCC / 2)] / sensitivity = acceleration in the x direction

Potentiometer

•0-12v controlled by user

•Step down to 0-5v•Previously installed •Controls the motor

controller •Will adjust output of

potbox according to power microcontroller

Microcontroller•PIC16F886 Microchip Technologies•28 Pin DIP•14 10 bit A/D Converters•2 8 bit Timers•2 Analog Comparators•2 Output 10bit PWM•Designed for Intelligent

Driving System

Development Board•28 Pin LIN Demo

Board, Microchip Technologies

•For Use with Most 28 Pin DIP PIC MCU’s

•Programmed with PICkit 2 Micorcontroller Programmer

Sensor Microcontroller

• 5 analog inputs (current, accelerometer, potentiometer, Temperature, and state of Charge )• Two PWM (speed,

rpm) • Reset • Heartbeat• 7 outputs to power and

data microcontrollers

Power Controller •7 inputs from sensor

microcontroller•Heartbeat •Computes optimum

acceleration▫Test Data ▫Peukert’s Law ▫Battery Resistance

•Outputs to safety microcontroller

Safety Microcontroller • 3 Inputs: Potentiometer,

Power MCU, and Reset• 3 Outputs: Motor

controller, WDT, and Data

• Acts like typical a comparator

• Prevents runaway acceleration

Data Microcontroller •7 inputs from sensor

controller•1 from Power, 1 from

safety•1 Reset,1 heartbeat •1 Output from

USBwiz to microcontroller▫3 ways

UART I2C SPI

Data Microcontroller:USBWiz

• Fully assembled and tested• 2 USB and SD connectors• Single 3.3 V regulator• Ready for 32 Khz crystal• Complete ‘C’ source code

library • Support fat file system• Easy connection with PIC and

AVR• 40 to 50 mA, power

consumption• 5v tolerant I/O pins• -40 °C to + 85°C temperature

operation range• Lead free.

WatchDog Timer • Used to monitor and

minimize errors• Timeout period and reset

period• Two types

▫Hardware (external)▫Software (internal)

Internal Watchdog Timer • Positives

▫Cost is essentially zero

▫Can save debugging information

▫Convenient▫Can modify timeout▫Can vary less with

temperature

• Negatives ▫Almost all can be

disabled by software

External Watchdog Timer• Positives

▫Cant be disable accidentally

▫Separate clock source▫Min/Max timeout

period▫Reset can connect to

other system▫Timeout period is

adjustable

• Negatives ▫Cost▫Timeout period varies▫One I/O line▫Timeout must be

calculated (both high and low speed)

Our decision • External • Capacitor adjustable

▫ Voltage monitoring▫ 1.565v to 5v

▫ Watchdog timeout▫ 700ms to 70s

(100pF to 100nF capacitor)

▫ Reset timeout▫ Preset, or 0.5 ms

to 5s by capacitor

Original Goals & Specifications

•Solar assisted EV conversion •Range of 60+ miles •User friendly display (touch screen) •DOT approved•Wireless applications•Regenerative braking •Power steering

Changes From Original Design• Batteries

▫12 12v swap for 24 6v (cost $2400)▫Battery weight from 1074 to 1488 pounds (38.5% increase)▫Not much engineering design required▫Main benefit would be longer battery life

• Touch Screen Display▫Lost computer engineering student in our group who was

working on this part• Solar Panels

▫Tecta America (who installs solar roof panels) advised us against using solar panels

▫Not enough surface area to produce enough energy to be worthwhile

Budget• Electric truck from Tecta America - FREE

Eagle PCB - $50• Microcontrollers – QTY 10 @ $2 each = $20• Development board – $40 • Op-amps – QTY 20 @ $0.38 = $8.00 • USBWIZ - $50• Speed Sensor – $49• RPM sensor – $99 • Hall Effect current sensor – $49• PakTrakr 600 EV sensor (Battery Temp and S.O.C.) – $150• Extra PakTrakr remote - $70• Accelerometer – $23• WatchDog Timer – QTY 15 @ $1.56 = $24• Soldering Iron with station (Amazon) – $50• Breadboard Kit (Amazon) – $25• Waterproof box – TBA (with final dimensions)

Miscellaneous (wiring, bolts, tax, shipping, etc) - $100Total Estimate: $807

• Old total : $3500 (with batteries and touch screen display)

Progress