Solar Car Electrical System Overview

1. Solar Car Electrical System Overview

2. Basic System Diagram CAN Bus 1 Solar Array Maximum PowerPoint Trackers Vehicle Control and Data Acquisition Computer HV Bus Telemetry Radio Battery Management System Battery Driver Display Motor Controller CAN Bus 2 Motor LV Bus Lights Rear View Camera DC/DC Converter

3. 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

4. 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

5. 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

6. Battery • LiFePO4 chemistry • Limited by World Solar Challenge regulations to 40kgs • Capacity of over 4kWhr • 125V nominal • Custom BMS with CAN interface module

7. 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

8. 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