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Difference between motor driver with and without position sensor


The starting and driving methods of motor can be roughly divided into two types: driving with position sensor and driving without position sensor.

motor driver
  1. Motor driving with position sensor: a motor driving method that requires sensors to detect the rotational speed and rotational position of the motor.

The advantages of driving with sensors are that the position and rotation of the motor can be accurately detected when starting and driving, and the motor drive and rotation control can be smoothly realized from low speed to high speed through the motor driver with built-in hardwired logic controller.

Disadvantages: Sensors such as Hall element/Hall IC must be installed in the motor, so it is necessary to consider the installation position accuracy of the sensor and the wiring connecting the sensor and the motor driver.

  1. Sensorless motor driving: a motor driving mode that does not require the above sensors.

Advantages of sensorless motor drive: It can be used to drive motors that cannot be physically equipped with sensors and motors exposed to adverse environments such as high temperature, water and oil.

Disadvantages: Because of the poor performance at low speed due to the use of speed electromotive force, and the rotation position is estimated through the calculation of MCU, the overall response performance is poor. In addition, the estimation using motor current, voltage and motor parameters (R and L of motor winding) instead of position and rotation detection sensors will be affected by individual differences of motors.

For sensorless driving, another method is to use the hard-wired logic special controller other than MCU to start with the external forced commutation signal, and then use the speed electromotive force as the position signal.