1. Solar Car Electrical System Overview

2. 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

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