Why is the vehicle control unit VCU of new energy
vehicles so important?
1. What is the vehicle control unit
The vehicle control unit VCU (Vehicle Control Unit) is a vehicle control unit, which belongs to the electronic control system of new energy vehicles and is the core control component of the entire vehicle. Its main functions include:
Receive information from various components, comprehensively judge the status of the vehicle, and realize coordinated control of multiple systems.
Control the high-voltage relay to close or disconnect, and complete the connection or disconnection of the high-voltage system.
Calculate the target torque of the vehicle based on the accelerator pedal, brake pedal, gear information and vehicle speed signal, and send the torque demand instruction to the power control unit PCU through CAN communication.
Control the power battery status and brake pedal position signal according to the status of ABS, calculate the energy recovery torque, and send instructions to the motor controller MCU to start energy recovery.
Send PWM signals to control the speed of the electronic cooling water pump according to the temperature of the motor, PCU, controller, coolant and vehicle speed signal.
When the vehicle collides or has serious faults, such as insulation fault, power battery overtemperature or overvoltage, power motor overtemperature or overcurrent, VCU will cut off the relay on the high-voltage circuit to ensure personnel safety.
2. Development of vehicle controller
The vehicle controller originated from traditional cars and landed in new energy vehicles. Traditional cars include engine controllers, transmission controllers, body controllers, chassis controllers, etc. Each controller is customized to solve the functions and performance indicators of its own components.
Due to the late start of domestic electronic control technology, until the rapid development of new energy vehicles, hybrid power urgently needs to solve the effective coordination between fuel power system and battery power system, and pure electric vehicles need to solve the power management of the whole vehicle. Therefore, the concept and function definition of the whole vehicle controller are clarified, laying the foundation for the rapid development of VCU.
3. Function of vehicle controller
The vehicle controller collects accelerator pedal signals, brake pedal signals and other component signals, and controls the actions of the lower-level component controllers after making corresponding judgments, driving the vehicle controller to collect driver driving signals and vehicle status, manage, dispatch, analyze and calculate network information through the CAN bus, and perform corresponding energy management for different configurations of vehicle models.
The main functions of the vehicle controller of pure electric vehicles include: vehicle control mode judgment and drive control, vehicle energy optimization management, vehicle communication network management, brake energy feedback control, fault diagnosis and processing, vehicle status monitoring and display, etc.
The vehicle controller collects the driver's driving signals and vehicle status, and issues instructions through the CAN bus to control the operation of each subsystem to keep the vehicle running normally.
Driver intention analysis
According to the driver's intention, the VCU issues instructions to the motor controller and then to the motor to output the appropriate torque and speed.
Vehicle mode management
Realize vehicle mode management and control, and ensure that the vehicle runs in a certain safe state through reasonable and clear mode transfer paths and conditions.
Braking energy recovery
The VCU analyzes the battery status and issues a braking instruction to the motor controller to recover some energy when the braking energy recovery conditions are met.
Monitoring vehicle status
The vehicle controller effectively identifies and manages the fault status of components and vehicle fault status by comprehensively analyzing the real-time information of each component.
