A Novel Commutation Torque Ripple Suppression Method for Position Sensorless Brushless DC Motor Based on SEPIC Converter and Phase Error Compensation

Commutation torque ripple of a brushless dc motor (BLDC) in the full speed range is one of the main problems which needs to be resolved. A new approach of minimizing commutation torque ripple for position sensorless brushless DC Motor Based on a SEPIC converter and phase error compensation was proposed. During the commutation period, the dc-link bus voltage is controlled by a new voltage switching circuit based on the SEPIC converter, so that the rate of a phase current decrement and the rate of another phase current increment are equal, which will dramatically reduce the non-commutated phase current ripple of the motor. Furthermore, a low-pass filter and a closed-loop correction method based on current integration are applied to make the position sensorless BLDC motor commutate accurately which will reduce the commutation torque ripple at the same time. The experimental results show that the method can effectively suppress the commutation torque ripple for the position sensorless BLDC motor.