Solar Car Electrical System Overview

Basic System Diagram Solar Array Telemetry Radio Battery 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

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