Phoenix Solar Racing
The electrical approach of the Phoenix SE Vehicle is different than the original Phoenix Vehicle.
Motors and Controllers
This updated vehicle incorporates two motors and two motor controllers, two Mitsuba M1096-III motor and controller sets. The two controllers are configured to work in conjunction with each other, and are operated from the same set of hardwired driver controls. They produce a combined 2KW nominal output and 5KW maximum.
The battery is a carry over from the original Phoenix. The battery pack is made up of 60 LiFePo4 pouch cells made by A123 (AMP20M1HD-A). The 60 3.2Vnom Cells are placed in a 30s2p resulting in a 96V nominal and 108V maximum pack voltage. The whole string has a datasheet specification of 40Ah, which from the 96V nominal voltage gives the battery pack 3840Wh of theoretical energy storage.
Battery Management System
The original battery management system that was made by A123 has been replaced with a Tritium IQ Battery Management System. This BMS satisfies all requirements for safety EXCEPT for electronic over-current automatic shutoff. The BMS will open Isolation contactors in overvoltage and undervoltage conditions at the cell level. The BMS will also open contactors if overtemperature is detected in either of the two battery modules. The Tritium BMS will also handle cell balancing. A separate device will monitor the main current measuring shunt, and disconnect the battery pack in an overcurrent situation. The battery pack has a 200A main fuse, and fuses are used whenever possible on signal wires inside the battery box.
The solar array has a usable solar area of 6m^2 and is composed of 391, Mono Crystalline Silicon Solar Cells. Produced by SunPower, model C60 “Bin J” solar cells are 22.5% efficient under maximum normal operating conditions. Seven series strings power seven different Maximum Power Point Trackers. These trackers are themselves in series with the other trackers, and collectively create the high voltage needed to charge the battery pack. This is so shaded parts of the array and tilted parts of the array do not impede the flow of power. This topology can be thought of as miniMPPTs in the place of Bypass Diodes. When a cell string is shaded, the MPPTs output a lower amount of power instead of being bypassed completely.
Low Voltage systems
The Phoenix SE is upgraded with an extensive diagnostics system for investigations into efficiency and to provide information for troubleshooting. Using a common data communication standard called CANbus, the system collects data from the motor controllers, MPPTs, BMS, and various custom sensors throughout the vehicle. The CANbus data system is also used to operate Vehicle Lights and Horn. Data is displayed using a tablet computer including, most importantly, vehicle speed and rear view camera. The drive electronics do not require the low voltage system to run, and the low voltage system does not require the tablet computer in order to run. Care is taken to make sure the low voltage system does not power the any part of the vehicle drive train including BMS, Motor Controllers ,or MPPTS.
The Low Voltage system uses a set of NiMH batteries with a total of 30,000mAh and 12.5V nominal. If and when they become depleted, a backup DC-to-DC 110V-12V converter will supply the LVS from the HVS battery. Power supplied to the LVS goes through a seamless transition between Aux batteries to DCDC converter. This is so the most necessary functions like Horn and Indicator lights continue to function.
Vehicle Design Report
PSR's Official submission: OSU_ASC2016VDR.pdf
This document only contains exactly when the ASC Regulations ask for, nothing more.
The Vehicle Design Report is a document that the event organizers of the American Solar Challenge want made so that they my look over aspects of your design long before the vehicle is raced. They want to verify that your vehicle is safe, mechanically and electrically. They also want to make sure you vehicle obeys rules of the competition, like car size and the array maximum total solar area.
The vehicle will go under rigorous inspections and testing at the event track in Pittsburgh, before it is allowed to race. They don't want you showing up with a car that is unable to pass the inspection!
Electrical System Block Diagrams
High Voltage Diagram
The High Voltage diagram was made for the Vehicle Design Report for review by the ASC officials.
I use to explain this system diagram to help explain to new members how the vehicle works.
It also helps me keep track of how the car works because even I sometimes forget peices.