Torque Ripple Reduction Method for Interior Permanent Magnet Synchronous Machine Drives with Minimal Loss

Torque ripple reduction for interior permanent magnet synchronous machine (IPMSM) drives has been widely discussed for high-performance applications, since the performance of torque and speed will be degraded by torque ripples. Torque ripples can be dramatically reduced by injecting harmonic currents with properly designed magnitude and phase, which can generate extra torque ripples to compensate for the original ripples. However, the injected harmonic currents will generate extra machine loss, including both conduction copper loss and iron loss. In order to further reduce the machine loss when reducing torque ripples by injecting harmonic currents, it is meaningful to take into account both conduction copper loss and iron loss by the injected harmonic currents. The main contribution of this paper is to present a torque ripple reduction method for IPMSM drives with minimal machine loss, based on the torque ripple model and the extended harmonic iron loss model of IPMSM. And harmonic currents are optimized to minimize both torque ripples and the machine loss by harmonic currents. Experimental results demonstrate the effectiveness of the proposed method in torque ripple reduction. Also, compared with the existing methods, as iron loss by the injected harmonic currents is considered in harmonic current optimization, the proposed method can further reduce machine loss.