Our Electrical System
Authors: Jonn Dillon, Zoe Goodward
QEV2 features a completely custom electrical system. Every board and system is built from the ground up to satisfy the specific needs of our electric vehicle.
The Chassis Controller is the main brain of the system. Its primary purpose is to take in the various driver inputs (pedals, steering angle, etc.), and use various software algorithms and control schemes to output the appropriate torque to each of the systems inverters/motors. Its secondary purpose is to provide a data level/transport layer of security for the car's systems. This means that if another board fails and locks up, or some system trips an error, then it can perform the appropriate operations to either correct the issues (rare), or shutdown the car safely. It's other functions include data aggregation (through sensors, and deciding what to do with that data), data distribution (sending saved data out though the Radio Pod), and state management (i.e. the cooling loop, electrical switches, RTD siren, etc.)
Chassis Controller V2 - Top Side
Chassis Controller V2 - Bottom Side
Chassis Controller V1
Power Distribution Module
The Power Distribution Module (PDM) controls the distribution of power throughout the Grounded Low Voltage (GLV) system. It allows power to the Chassis Controller, the Battery Management System (BMS), inverters, radio pod, steering wheel display modules, dashboard, brake light, RTD siren, and the cooling loop (fans and water pumps). It's primary role is to monitor the current draw from the various systems and to act as a fuse box in the event of system error or failure. The PDM follows a very basic system of operation: when the GLV system is turned on, the PDM will allow power to flow through to the other systems/boards. It then waits until it receives a message from the Chassis Controller over CANBUS. These packets of data will instruct the PDM on whether to turn on or off the RTD siren, brake light, fans and pumps or to shutdown any boards or systems.
PDM - Top Side
PDM - Bottom Side
The High Voltage (HV) board is responsible for performing current sensing across the entire HV loop in the car. As per rule requirements, the use of an Insulation Measurement Device (IMD) is required to achieve this. This device will trigger if a HV loop is detected within the shield point of the car (chassis and GLV). Additionally, the HV board contains the logic circuitry for the TSAL (see below).
Steering Wheel - Top Side
Steering Wheel - Bottom Side
Tractive System Active Light (TSAL)
The TSAL acts as a visible indicator of the state of the tractive system within the car. It is to warn those around the car that HV is active and the car may be dangerous to interact with. In this state the LEDs flash red. When HV is off, the green LEDs are on to signify that the car is in a safe state. This logic is controlled by the HV board.
The Shutdown board is center of the shutdown loop and all it's associated functionality. The shutdown loop runs through the Brake System Plausibility Device (BSPD), accumulator, pre-charge / discharge overload circuitry, and the AIRs (contactors). The board can detect the individual shutdown segments so in the event something fails the support team monitoring, the car can know what it was. The Shutdown board can also shutdown various systems through software.
Shutdown Board - Top Side
Shutdown Board - Bottom Side
Steering Wheel Display Module
The car's steering wheel has an inbuilt OLED display that acts as the drivers interface with the car. When in a ready to drive state, the display will show the car's torque output, a lap timer, acceleration, brake levels, speed, regen efficiency, percentage of battery remaining, etc. Crucially, the screen displays any error states or warnings to the driver that the Chassis Controller has detected. When the tractive system is disabled, the driver has the ability to customise the settings of the car and choose what kind of event the car will be participating in to optimise performance.
Steering Wheel - Top Side
Steering Wheel - Bottom Side
Sensor Node / Development Board
The sensor board was developed with two primary focuses: firstly, to create a small board sensor node that could enable CAN communication with any kind of sensor placed throughout the car, and secondly to act as development board flashed with the Arduino environment to provide a simpler, more user-friendly environment to teach younger members of the team the basics of embedded systems programming, whilst providing solid programmable platform enabled with CANBUS, an SD Card etc for more experienced members.
The radio pod allows for wireless communication between the car and Support Team. This allows live tracking of crucial car data including, but not limited to, battery voltage and temperature, power output, as well as the status of all systems within the car. Ideally all messages on the CAN Broadcast bus will be transmitted to the team monitoring the car. This will allow any issues to be detected early and resolved before they become problems. Additionally, the radio pod acts as a secondary form of communication with the driver. The Support Team can also send messages back to the radio pod to either request a specific piece of data or remotely control and change the car's various systems while the tractive system is disabled.
The brake light is a simple array of red LEDs used to signal that the car is breaking. This is achieved by the Chassis Controller sending a message over CAN to the PDM when it detects the brake pedal being activated.
Systems In Development
We have a number of systems in development for the long term continuation of the project:
Pit Computer / Software
Using Electron and React running on a Raspberry Pi or team members computer, storing and performing real time calculations on the live data from the car, via the radio / telemetry system
Motec compatible Lap counter / timer system, using 38kHz signalling
New Radio Pod
Testing everything in the car via single cable
Customised real time CANBUS display