How MCU(Motor Control Unit) Works in Electric Vehicle? Diagram

The Motor Control Unit or MCU is a very important part of an electrical vehicle. It controls the speed and torque of the electric motor. It also takes care of other important factors such as overcurrent faults, safety, the direction of rotation, etc. There are two types of MCUs available in the market. One of them is used to control the DC motor while another one is used to control the AC Motor. In small vehicles, such as Electric Bicycles and electric Scooters, generally, a DC motor is used. And here, a basic motor controller is used means there is no vehicle control unit(VCU), it is directly operated by the user. 

On the other hand in large vehicles such as electric buses, four wheelers, an AC motor(induction motor) is used. Here, the vehicle control unit is also available. The MCU is connected to the VCU with CAN or LIN, or UART communication channels. Here, the VCU gives commands to the MCU to operate. 

The DC motor controlling unit has a DC-DC converter and it just converts the voltage and current provided to the motor. But the AC motor controlling unit has a DC-AC converter that converts the DC power supply into a three-phase AC power supply before providing it to the Motor. It is built with high-power IGBTs. Here, voltage, current, and frequency all are controlled according to the command from the motor control unit. The Pulse Width Modulation(PWM) technique is used to operate the power converter. So there is the only difference between a DC controller and an AC controller, that the type of power converter they use, other all the functions are the same in both types of converters. Also, remember that the MCU during the vehicle braking the motor generates reverse power that is used to recharge the battery.

Motor Control Unit(MCU) Block Diagram

Here, you can see the block diagram of the Motor Controller Unit

You can see in the above block diagram, the MCU is built with a Microcontroller or Microprocessor and some additional devices. Basically, it takes inputs from different sources and after processing them it generates a control signal that is provided to the power converter, so the motor will rotate as the users want.

For example, when we push the forward or reverse switch, the microcontroller can understand and it generates a control signal that will rotate the motor in a forward or reverse direction.

Similarly, when the throttle is operated the microcontroller will control the speed of the motor.

The microcontroller also takes inputs from the protection sensors to sense the overcurrent, voltage, or overheating fault. And according to it, it activates the alarm or stops the motor.

As I told you, in large vehicles, the MCU is connected to the Vehicle Control Unit. So, it shares the important data with the VCU and operates as per the command from the VCU.

So, the power converter and microcontroller are the main two parts of the MCU. And the rest circuits and components help to provide input to the microcontroller.

Read Also: 

• What is Plugging in Electrical Motor and Braking System?
• What is Universal Motor Controller(UMC)? Features, Applications
• Different types of Drives and Motors Used in Robotics
• Under Voltage and Over Voltage Effect on Motor Explained
• Actual Difference between Servo Motor and Stepper Motor

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