Torque Ripple Minimization in Brushless DC Motor with Optimal Current Vector Control Technique

Brushless DC Motor (BLDCM) inevitably suffers from commutation torque ripple due to stator inductance and the finite dc-link voltage, which may degrade the torque performance. This paper analyzes the commutation torque ripple under traditional two phase on operation in vector coordinate system. Based on the analysis, this paper presents a novel drive method of BLDCM with vector control to minimize commutation torque ripple. In this method, the optimal current vector can be obtained by calculating constraint equation of both torque ripple minimization and maximum torque per ampere characteristic (MTPA), which avoids control method switch between normal conduction period and commutation period and improves system reliability. Simulation and experimental results for a 3.7kW BLDCM are presented to validate the proposed method.