Introduction to Vehicle Controller VCU for New Energy Vehicles

01 Composition

The vehicle controller is mainly composed of hardware and software. The hardware includes the shell and hardware circuit, and the software is divided into application software and underlying software.

The shell is mainly used for the protection and sealing of hardware circuits. It must meet cleanliness requirements such as waterproof and dustproof, as well as mechanical requirements such as avoiding falling and vibration.

The hardware circuit is mainly composed of the main control chip (32-bit processing chip) and peripheral clock circuits, reset circuits, and power modules. It is generally also equipped with digital signal/analog signal processing circuits, frequency signal processing circuits, and communication interface circuits.

Application software and underlying software are generally written in C language. Application software is mainly the upper-level control strategy, which is mainly responsible for real-time control of energy flow and distribution ratio according to vehicle status and driver intention. The underlying software is mainly responsible for the initialization of the microcontroller, real-time transmission and reception of CAN bus signals and input, and real-time processing and diagnosis of output signals.

02 Function

Drive system control

According to the driver's operating intentions such as the position of the accelerator pedal, gear position, brake pedal force, etc., the parameters such as the torque required by the electric motor are calculated, and the movement of various power components is coordinated to ensure the normal driving of the electric vehicle.

Vehicle Energy Management and Optimization

According to the actual working conditions, the whole vehicle is managed, the charging of electric vehicles and the recovery of braking energy are monitored, and other electrical equipment on the vehicle is controlled to achieve efficient energy distribution, improve the economy of the whole vehicle, and extend the service life of the whole vehicle.

Vehicle communication and network management

In addition to the vehicle controller, electric vehicles also have various sub-control systems such as the motor controller and battery management system. These controllers need to communicate with each other. The vehicle controller connects the various sub-control systems together through the CAN communication network and coordinates the management of the entire communication network.

Troubleshooting and diagnosis

Monitor the operating status of each device in real time, diagnose, prompt and actively repair any abnormal situations to ensure the safe operation of electric vehicles.

Car status display

The vehicle status information is collected and processed, and important status and fault information is sent to the instrument for display, such as vehicle speed, motor speed, remaining battery power, motor or battery fault information, etc.

03 Working Mode

Self-Test Mode

When the key door signal is in the ON position, the self-test mode is started, and the vehicle controller is powered on for self-test. If the self-test passes, it waits for the start mode. If the self-test fails, it enters the fault mode.

Startup Mode

When the key door signal is in the START position and the self-test mode is passed, the vehicle controller will wake up other nodes on the vehicle's CAN communication network (motor, converter, air conditioning system, etc.) to start working and power on high voltage. When all equipment is started normally, the vehicle enters the READY state, and the READY light on the instrument is on, indicating that the driver can perform normal driving operations and complete the startup mode.

Start Mode

When the driver starts the vehicle without stepping on the accelerator pedal, the vehicle controller will coordinate the motor torque to reach the starting target value, the vehicle speed will gradually increase, and it will be controlled within a reasonable speed range to achieve a smooth start.

Driving Mode

During the driving process of the car, the vehicle controller collects information such as the driver's accelerator pedal position and opening change rate in real time, and controls the torque of the motor and the output power of the power battery in real time according to the current driving status of the vehicle (vehicle speed, battery current, voltage, temperature, etc.), thereby controlling the operation of the car according to the driver's intention, realizing forward, reverse, cruising, acceleration, etc.

Braking mode

When the driver steps on the brake pedal and the car is in braking or decelerating state, the vehicle controller calculates the required braking torque according to the current vehicle driving state, controls the electric motor to switch to engine mode, and charges the power battery.

Parking Mode

When the driver turns off the key, the vehicle controller controls the subsystem power, and the equipment is turned off to complete parking.

Failure Mode

When the vehicle controller detects a vehicle fault, it will activate self-diagnosis and active repair functions, limit system power output, put the vehicle into speed limit or emergency stop state, and display fault information to the driver.

Charging Mode

When the charging gun is plugged in, the charging motor starts working, the vehicle controller will coordinate with the battery management system to start charging, and continuously monitor the status of the battery management system and the charging motor, and display the charging information to the driver; when a fault occurs during the charging process, the vehicle controller will promptly cut off the battery management system relay to interrupt the charging process.