Common variable frequency motor include : three-phase asynchronous motors, brushless DC motors, brushless motors and switched reluctance motors. Here we explain the principles of inverter motor control what ?
Inverter motor control principle
Inverter motor control strategies usually are: the base speed constant torque control , constant power control above base speed , ultra- high speed range weakening control .
Base rate: As the motor would run counter electromotive force is generated , and the counter- electromotive force size is usually proportional to the speed . Therefore, when the motor is running to a certain speed , due to the size of the counter electromotive force applied voltage of the same size , then called the base rate of speed .
Constant torque control : motor at the base speed , the constant torque control . At this speed is proportional to motor back EMF E and the motor. And motor output power and motor torque and speed proportional to the product , so this time is proportional to motor power and speed .
Constant Power Control: When the motor speed exceeds the base by adjusting the excitation current to the motor so that the motor 's back-EMF remained constant , in order to improve the speed of the motor . At this time , the motor output power remains substantially constant , but inversely proportional to the motor torque and speed decrease .
Weakening control : When the motor speed exceeds a certain value , the magnetizing current is quite small , basically can not be adjusted, this time into the field weakening control phase .