Solar Car Electrical System Overview

Basic System Diagram

Solar Array

Battery

Motor

Maximum PowerPoint

Trackers

Battery Management

System

Motor Controller

DC/DC Converter

Driver Display

Lights

Telemetry Radio

Rear View Camera

Vehicle Control and Data Acquisition

Computer

CAN Bus 1

CAN Bus 2

HV Bus

LV Bus

Solar Array

• 6m2 SunPower B30 monocrystalline silicon cells

• Split into 4 sub-arrays• Specialist encapsulation, increasing efficiency

by ~4%• 22% efficient overall• 1.3kW measured max power output• Value: £22,500

Maximum PowerPoint Trackers

• Also known as MPPTs• Built to custom specification by

Drivetek• Essentially a DC/DC converter,

converting array voltage to HV bus voltage

• 98% efficient• 4 MPPTs, one to interface with each of

the sub-arrays of solar cells

Motor & Motor Controller

• 1.8kW CSIRO 3-phase brushless DC hub motor

• 98% efficient• 4kW peak power• Custom designed hub, machined by

Cambridge Precision• Value: £18,000• Motor Controller: Tritium

Wavesculptor• Value: £5,500

Battery

• LiFePO4 chemistry• Limited by World Solar Challenge regulations

to 40kgs• Capacity of over 4kWhr• 125V nominal• Custom BMS with CAN interface module

Control and Data Acquisition

• Entire solution provided by National Instruments CompactRIO

• Interfaces with CAN busses• Driver inputs and vehicle

instrumentation connected directly to modules

• Telemetry radio connected to serial output port

Control and Data Acquisition

• High-speed control loop run in FPGA, providing fast, reliable response to driver inputs

• Background loop run in Real-Time Controller• Sets maximum allowable currents• Determines preferred speed for cruise control• Logs all data• Selects data to be transmitted over telemetry, to

minimise power consumption