Main functional specifications for motor drive MCU
Time:2023-04-10
Views:1006
Power on/off management:
After the MCU completes the initialization self check, it is determined whether the input voltage of the MCU has reached 95% or more of the bus voltage, and whether the high voltage has been successfully applied. After the high voltage is successfully applied, the MCU enters the working mode, receives the gear signal sent by the gear controller and the torque request signal sent by the VCU, and executes torque output. When the VCU sends a power down command, the BMS feedback relay is disconnected, and the MCU enters the active discharge mode to control the voltage to drop below the safe voltage, completing the power down.
Torque control:
When the VCU sends a target torque signal, the MCU controls the IGBT operation through the PWM signal sent by the main control board. The IGBT converts direct current into three-phase alternating current to control the motor operation. When there are faults in the electric drive system such as overvoltage, overheating, overcurrent, rotation, interlocking, insulation, collision, etc., the torque control output will be 0;
Forward and reverse rotation of the motor:
The MCU receives the execution gear sent by the VCU, and changes the conduction order of the IGBT to achieve the forward and reverse rotation of the motor, enabling the vehicle to reverse and move forward.
Active discharge function:
When the VCU sends a power down command, the MCU responds to the active discharge command sent by the VCU, reducing the high-voltage circuit voltage below the safe voltage.
Crawling control:
When the vehicle is in driving mode and the driver has not pressed the accelerator and brake pedals, the MCU controls the output torque based on the motor speed to control the vehicle‘s speed.
Park Slope - Zero Speed Control:
Based on the vehicle‘s gear, operating status, vehicle speed, battery status, motor status, requested torque, slope, and other information, it is determined whether to enter the parking mode. When the parking mode is activated, the MCU enters zero speed mode, which is the parking mode.
Anti shaking:
Tip in Tip out, a sudden change in torque output, causes vehicle speed jitter, especially on low adhesion road surfaces. Therefore, when the torque change rate is too high, the MCU should identify the amount of vehicle speed jitter based on the vehicle speed, and then use certain torque compensation to eliminate the jitter.
Energy recovery:
When the vehicle is in driving mode, consider the vehicle‘s speed, SOC, battery status, and other control states of the vehicle to determine whether to enter energy recovery mode. When the driver releases the pedal, as the motor speed decreases, the rotation of the wheels will drive the motor to rotate, turning it into a generator. At the same time, the MCU, based on the torque emitted by the VCU, combined with the torque control and power limit of BMS and other controllers, real-time controls the large and small changes in current, and also controls the deceleration of the vehicle.
Thermal management function:
When the temperature of the motor and electronic control is greater than a certain temperature threshold, turn on the fan and water pump at a specific temperature threshold.
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