An Incorporated Control Strategy of Commutation and Conduction Torque Ripples Mitigation for BLDCM Drives in Household Appliances

In this paper, an incorporated control strategy of both commutation and conduction torque ripples mitigation for brushless DC machine (BLDCM) with the sinusoidal back electromotive force(EMF) is proposed to reduce the vibration and noise of household appliances for higher comfortable capability. Based on the combined torque ripple analysis with respect to the stator flux linkage trajectory, a three-phase voltage vector injection (TVVI) method is designed and implemented in the commutation interval to compensate the sharp dips of the stator flux trajectory for the mitigation of the commutation torque ripple, and duty cycle of the injected voltage vector could be regulated automatically. Then, a simple direct power control (DPC) method with TVVI in the PWM modulation is employed as inner-loop for BLDCM to obtain the desired waveforms of currents with the specific dc-link current sampling method, and the reduction of both conduction and commutation torque ripples is achieved. The proposed incorporated control strategy is validated through simulation experiment results, and the effect on the torque ripples are compared with the traditional approaches.