Sensorless Brushless DC Motor Commutation Method Based on Angular Acceleration

In variable-speed conditions, brushless direct current (BLDC) motors undergo changes in rotor speed, which affect the waveform of the motor's back electromotive force (EMF). In such scenarios, the conventional method of detecting commutation points for sensorless BLDC motors, which involves delaying the electrical angle by 30 degrees after the zero-crossing of the back EMF, cannot accurately determine the commutation points. This, in turn, leads to an increase in torque ripple. To address these issues, this paper proposes a sensorless BLDC motor variable-speed commutation estimation method based on angular acceleration. This method involves real-time calculation of the delay time after the zero-crossing of the back EMF to accurately estimate the commutation points. Experimental results validate that the control method proposed in the paper can accurately determine commutation points under variable-speed conditions, ensuring the smooth operation of the motor.