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
