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A Novel Commutation Torque Ripple Suppression Method for Position Sensorless Brushless DC Motor Based on a SEPIC Converter

Commutation torque ripple for a brushless dc motor (BLDC) is a key problem to be researched widely. A novel commutation torque ripple suppression method for the position sensorless BLDC motor based on a SEPIC converter was proposed. In the commutation interval, the dc-link bus voltage is controlled through a new switching circuit based on the SEPIC converter. It gives rise to the equal rates of current decrement and increment between commutated phases, which dramatically reduces the current ripple of the noncommutated phase. Furthermore, a new automatic correction method of phase error with an analog filter was proposed to make the position sensorless BLDC motor commutate precisely and reduce the commutation torque ripple at the same time. The experimental results showed that the new proposed method effectively suppressed the commutation torque ripple for position sensorless BLDC motor.