Car Architecture
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Mechanical
Our vehicle is a single motor + differential car. Many other teams have more sophisticated drivetrains, including setups with hub motors, which allow you to eliminate all spinning shafts inboard of the wheels.
We have stuck with the traditional single motor + differential setup for simplicity.
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Electrical
Overview
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Shutdown Circuit
The shutdown circuit (Described in EV.7.2) is a safety mechanism which serves to disconnect the Tractive System either automatically or manually. This is done through a series of switches and interlocks which can break power supply to the IR'S thus isolating the Tractive System from the outside world to protect us from the high voltage. For specifics on the wiring, see the drawing below.
CAN (Controller Area Network)
CAN is a rugged information bus protocol that allows many devices to communicate with one another over a limited number of wires (two per bus). This means that devices can only communicate with other devices on the same bus (unless they use another device which is on both busses as an intermediary).
On NFR25 we originally designed to have two separate CAN busses but have modified our designs to use a single bus instead.
Our two CAN busses are called DATA and DRIVE CAN. DATA is (as the name suggests) intended for purely data acquisition purposes and is not drive critical. DRIVE contains information directly related to controlling the driving of the car and is drive critical. There are two buses to reduce the bus load of any one bus which is intended to make the car's communication network more robust.
The drawing below denotes which devices are connected to which CAN busses, arranged as to approximate location within the car.
Battery Structure
Accumulator
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The Accumulator is the high voltage battery which supplies the power that drives our motor. It is important to exercise caution when handling the Accumulator
Full Pack Electrical Structure
| Cells | Configuration | Max Voltage | Nominal Voltage | Capacity | Fused Current |
|---|---|---|---|---|---|
| Molicel p45b | 5 Series Segments see table below | 588 V | 504 V | 13.5 Ah | 80 A Fuse Datasheet |
Single Segment Electrical Structure
| Cells | Configuration | Max Voltage | Nominal Voltage | Capacity | Fused Current |
|---|---|---|---|---|---|
| Molicel p45b | 28s3p | 117.6 V | 100.8 V | 13.5 Ah | 80 A |
Low Voltage (LV) Battery
The LV Battery powers everything other than the Tractive System. It's located in the #LV Box. The mechanical structure is designed by the Accumulator Subteam and the electrical structure is designed by the Power Distribution Subteam.
Electrical Structure
| Cells | Configuration | Max Voltage | Nominal Voltage | Capacity | Fused Current |
|---|---|---|---|---|---|
| Molicel p42a | 6s3p | 25.2 V | 21.6 V | 12.6 Ah | 40 A Fuse |
Power Distribution
All GLV power is supplied by the LV Battery. It runs throughout the car at an unregulated voltage straight from the battery (20-25V generally). It is then regulated down on a per-board basis as needed. Some projects like the Wheel Brokers have regulated voltage being fed to them from a parent board over a short distance.
Enclosures
Dashbox
Contains ECU and Front DAQ boards as well as housing the Dashboard and mounting the Cockpit Shutdown button and Inertia Switch.
LV Box
Contains the Power Distribution Module and Low Voltage Battery Management System (LV BMS) as well as the LV Battery.
Accumulator
Contains the HV Battery as well as the HV BMS Daughterboards for pack monitoring.
Penthouse
Contains all of the HV related electronics. This includes the High Voltage Battery Management System (HV BMS), HV Board and IMD, Contactors, Energy Meter, Voltage Indicator Board (VIB), and Precharge Resistor.
Inverter
Contains the Motor Controller / Inverter, Manual Service Disconnect, and the DC Link Capacitor.
Backbox
Contains the Telemetry Board and the Dynamics Board.