Solar Car Electrical
System Overview

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

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