System for Motor Control in a Solar Powered Electric Race Car

System for Motor Control in a Solar Powered Electric Race Car

Jay OattsDuncan Thompson

Pavel RybakovAlex Jenkins

Ed Kfir

Monday November 1, 2010

Solar Jackets – Motor Controller Group ECE 4007L01 – ws3

Project Overview

• Design motor controlling system for solar-powered race car to participate in 2011 World Solar Challenge in Australia

• Modular design for efficient portability to solar racer and integration with full electronics system

• Expected cost of replication for Solar Jackets is approximately $550


Technical Objectives

• Design test bench and implement safety mechanisms

• Test functionality of motor controller and motor (donated items)

• Operate motor controller via single-board computer program and discrete controls

• Output vital data from motor controller to driver via LCD screen


Current Status• Test bench construction complete• Motor controller and motor functional (only

one of each)• Operation in discrete (human interface) and

serial (computer interface) confirmed• Safety systems installed• Semi-full systems test passed (SBC and LCD

excluded)


Latest Test Run


Modular Design


Modular Design

• Power Source


Modular Design

• Power Source• Motor Controller


Modular Design

• Power Source• Motor Controller• Motor


Modular Design

• Power Source• Motor Controller• Motor• Discrete Controls


Modular Design

• Power Source• Motor Controller• Motor• Discrete Controls• SBC


Modular Design

• Power Source• Motor Controller• Motor• Discrete Controls• SBC• Driver Display


Power Source - Batteries

• 8 x 12V series connection

• 96V effective• Wiring – AWG-4


Power Source - Fuse

• 250V / 150A rated fuse and holder


Power Source – Main Power Cutoff

• 48V/96V blowout• 1000A• Keyed access


Power Source – Power Relay

• Contactor– 900V / 500A

(cont.) / 2000A (cutoff)

• Power Resistor– 100Ω/200W


Motor Controller - Connections

• Battery Terminals



• Battery Terminals• Motor 3-Phase Power



• Battery Terminals• Motor 3-Phase Power• Motor Sense (15 pin)



• Battery Terminals• Motor 3-Phase Power• Motor Sense (15 pin)• Discrete/Serial

Controls (25 pin)




Controls (25 pin)• Fan Power




Controls (25 pin)• Fan Power• Fans (2 x 24V)


Motor Controller - Communication• Split from 25 pin controls cable • Serial-USB for computer • Hyperterminal program• Serial syntax

– Commands (same as discrete + program/operate mode + hard reset)

• XX!

– Queries• XX? (RAM)• XX> (EEPROM)

– Assignments• XX=# (RAM)• XX<# (EEPROM)

– (*Must be in programming mode)


Note: XX implies register hexadecimal number for RAM/EEPROM or command number. # implies decimal value to be assigned to the register

Motor• 3 phase cables connect to

attract rotating permanent magnet in sequence

• Controller sends power to phases relative to desired speed/torque (commutator)

• Motor sense cable sends information back to controller (Hall effect sensors, temp sensor, connection sense)

• Mount for support/stability


Discrete Controls - Switches• Enable

– Master controller enable (must be on to operate)




• Throttle Enable– Phase current enable

(drops to zero when disabled, but regen still operational)




• Throttle Enable– Phase current enable

(drops to zero when disabled, but regen still operational)

• Direction Switch– Forward or Reverse


Discrete Controls – Output Signals• Brake (Regen) Light

– Activates anytime the controller is regenerating power back to batteries (Phase current negative)




• Reverse Light– Activates when reverse

switch set (as long as motor is currently rotating forward)




• Reverse Light– Activates when reverse

switch set (as long as motor is currently rotating forward)

• Speed Pulse– State change every two

consecutive commutations


Discrete Controls – Pedals• Throttle

– Analog input (potentiometer for now) to scale throttle from 0-5V




• Regenerative Braking– Same as throttle, but

scales amount of regeneration to batteries from motor




• Regenerative Braking– Same as throttle, but

scales amount of regeneration to batteries from motor

• Air Gap – Mentioned in manual, but

ultimately unused


Single Board Computer (SBC)

• Serial interface cable connects to serial port in place of laptop




• 1x 10/100 Ethernet, 2x USB2.0




• 1x 10/100 Ethernet, 2x USB2.0• Boots Linux in about 3 seconds• RS-485 multi-drop network for

communication with solar cell switching power supplies

• Connects and operates LCD driver display


Driver Display• Potential display choice• Connects to SBC on

either SPI or I2C bus• LED backlighting• Many colors available• Affordable for basic

testing• Nothing purchased yet

and open to feedback


F R Cruise Control

Speed: 55 mph @ 1200 RPMRegen: 0% 100%

Power Supply: 96.3V / 20.2AMotor Temp: 30°CController Temp: 25°C

Acceptance Testing• Confirmation of functional motor controller

– Connect to 60V power supply at minimal current, measure input/output pin voltages (+5V for signal lines, +24V for fan)

• Full controls and motor connection– Communication with motor controller, motor rotation, discrete

controls operational, fans connected, 870dHz measured rotation (1740 RPM estimated)

• Battery array connection (full power operation)– Torque vs. speed control testing, safety systems operational,

96.3V measured battery power, 200mA full speed (no-load) current draw


Current Issues - Motor• Motor pole count

– Total number of poles not listed in any manuals– Needed to confirm speed calculation from motor

controller • Torque (phase current) control spiking

– Without load, current spikes at turn on to reach max speed and then levels out to nominal current draw

– Need to load motor to further test current range


Current Issues - Controls• Regenerative braking lights

– Signal every time negative current is recognized by the motor controller (regeneration)

– Not an effective sign of actually braking (light can trigger without regen being applied)

• Throttle/Regen potentiometers (sensitivity)– Current max measured at about half of potentiometer max range– Motor controller registers can modify range and deadband settings

to optimize• LCD screen choice

– Need to decide on LCD screen so information can be viewed continuously from program


Upcoming Milestones• Basic single board computer I/O

– November 5, 2010• Basic functional LCD user interface

– November 12, 2010• System logic programmed

– November 19, 2010• Automatic programmed motor control

– December 1, 2010


Discussion• Regenerative braking lights• Torque control spiking (need to load test)• Throttle/Regen potentiometers (sensitivity)• LCD screen decision• Motor pole count


Brake Lights

Reverse Lights

Motor Controller Interface Cable


Detailed Full System


NGM-EV-C200-092

Motor Controller

Cooling Fans

AMP Series 1 CPC 11-4

SC-M150-008

Axial Flux, Permanent Magnet,

DC Brushless Electric Motor

Phase Leads (AWG 4 Wire)

ABC

Motor Communication

Link

DB-15

8 x 12 V Car Battery Series

Array

96 V Effective

120VAC Charger

Wheel(Load)

Linux On-Board Computer

+ve

Power bus(AWG 4 Wire)

-ve

Vehicle Control Signals(DB-25)

Throttle Pedal

User InterfaceLCD Screen

RS-232

SpeedSupply Voltage

Motor TemperatureBrake Regeneration

RPMsDirection

Control Interface

Cable

Switches-Controller Enable-Throttle Enable

-Forward/Reverse Toggle

Cruise Control Buttons-Set

-Accel-Decel-Coast

RS-232

Brake Pedal

Reverse Lights

Brake Lights

Cost AnalysisPart Approximate Price

Littelfuse Slo-Blo Fuse $35

Fuse Holder $55

Kilovac EV-200 Series Contactor $80

Power Resistor $12

Curtis/Albright Battery Disconnect Switch (with recommended extra contacts for 12V line)

$90 ($120)

24V Brushless Fan (x2) $20

CPC Fan Connection Plug (and 2 connector pins) $5

TS-7250 SBC (with full duplex RS-485) $150 ($165)

AWG-4 Cable (and terminal connectors) $50

TOTAL SUGGESTED COST $542


System for Motor Control in a Solar Powered Electric Race Car

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