Detailed explanation of automobile motor controller
The motor control unit (MCU) is the core electronic module of electric vehicles. It is located between the battery pack and the motor and is responsible for controlling the speed and acceleration of the vehicle according to the driver's throttle input. The core function of the MCU is to convert the DC power provided by the battery into AC power to drive the motor through the voltage source inverter (VSI) and pulse width modulation (PWM) technology.
In this process, the MCU uses feedback from the position sensor to generate PWM pulses to control the motor speed and torque by adjusting the on time/duty cycle. In order to achieve efficient and precise motor control, the MCU uses a vector control method/field-oriented control (FOC), which allows independent control of torque and flux, thereby achieving fast and efficient motor drive.
The basic functions of MCU (motor control unit) mainly include:
1. Voltage conversion: MCU converts the DC power of the battery into three-phase AC power to drive the AC motor. This process is achieved through an internal inverter, using semiconductor switching devices such as transistors or IGBTs to control the frequency and amplitude of the current.
2. Speed and torque control: MCU adjusts the motor speed and torque according to driving conditions to adapt to different driving needs.
3. System protection: MCU has a variety of protection mechanisms, such as battery input protection, fault detection, motor controller body fault protection, overload protection, etc., to ensure the safety and stable operation of the system.
4. Diagnosis and feedback: MCU can monitor the system status in real time and provide feedback to other control systems of the vehicle, such as battery status, motor temperature, controller temperature, etc.
5. Communication interface: MCU has the ability to communicate with other systems (such as battery management system BMS, in-vehicle infotainment system, etc.) to achieve data sharing and system collaboration.
6. Thermal management: MCU contains temperature sensors and cooling systems to ensure that the appropriate operating temperature is maintained under high load conditions.
7. Electromagnetic compatibility: The MCU design takes into account electromagnetic compatibility (EMC) to reduce the impact on other electronic systems of the vehicle.
8. Modular design: The MCU may adopt a modular design to facilitate maintenance and upgrades.
9. Start/stop motor: The MCU is able to control the start and stop of the motor, gradually increasing the current when starting and gradually reducing the current when stopping.
10. Change the direction of motor rotation: The MCU can change the direction of current, thereby changing the direction of motor rotation.
11. Regenerative braking: The MCU controls the motor to operate as a generator during braking, converting kinetic energy back into electrical energy and storing it in the battery.
