Sensorless Control of Seven-Phase PMSM Drives Using NSV-SVPWM with Minimum Current Distortion

Abstract

This paper introduces three different algorithms to track the saliency in the seven-phase PMSM to obtain sensorless speed control. These algorithms are based on measuring the amount of change of the stator currents when different active vectors are implemented using the Near Six Vectors-Space Vector Pulse Width Modulation (NSV-SVPWM). Then, a comparison between these algorithms in terms of the Total Harmonics Distortion (THD) associated with implementing each algorithm is presented. The increase in the current distortion in these algorithms is related to the fact that narrow active vectors in these algorithms should be extended to tmin (8 us) for proper measurement in the current dynamics due to the oscillation in the currents. However, since the time duration of these active vectors in NSV-SVPWM will be 2.52 times longer than others, it is found that using these long active vectors will result in minimum current distortion. Simulation results are provided to investigate the effect of using the dynamic response of different active vectors on the THD of the current. Moreover, the results demonstrate the effectiveness of the proposed control technique to maintain the performance of the seven-phase PMSM motor drive post the failure in the speed sensor.