Simple expressions for optimal current waveforms for permanent-magnet synchronous machine drives

Current waveform shaping, which can be used to mitigate torque ripple and reduce rms current in permanent-magnet synchronous drives, is revisited. Previous work involved limiting assumptions and relatively complex formulations for the optimal current waveforms. In this work, the assumptions are removed, and simultaneously, far simpler expressions are set forth. The formulas developed are verified with simulation by experimentation. An interesting result is that failure to account for asymmetry and imbalance can lead to torque ripple that is on the order of the cogging torque in some machines. This work overcomes this problem with no extra effort.