Torque ripples and noise reduction in permanent magnet synchronous motor

This work investigates the minimization of torque ripples and harmonic noises in PMSM generated due to inverter switching system. To study how different voltage modulation schemes and control algorithms can influence the level of ripples and harmonics, MatLab models for FOC, HDTC and SVMDTC have been constructed to hold the study under the same operating conditions. It is evidence from the result that changing the control algorithm can affects the ripple level significantly when the applied number of vectors per sampling period is increased. To reduce torque ripples and harmonic noises in PMSM, three different methods have been proposed. In the first method a new passive filter topology for FOC and HDTC algorithms have been proposed. The filter topology consists of compound dissipative filter cascaded by RLC low pass filter. The compound filter has two tuning frequency points, one at inverter switching frequency and the other at some average selected frequency. The simulation results show that the proposed topology is effectively reduces torque ripples as well as current THD and EMI noise level. In the second method an active filter topology have been proposed. The topology consist of IGBT active filter and two RLC EMI noise filters. The active filter is characterized by detecting the harmonics in the motor phase voltages by comparing the measured phase values with reference voltages generated as function of the motor parameters and control setting values under field oriented control. The simulation results of this method show considerable torque ripples reduction in steady state range and adequate dynamic torque performance as well as considerable harmonic level reduction. The third method describes a new direct torque control algorithm for IPMSM to improve the performance of HDTC. The algorithm uses the output of two hysteresis controllers used in the traditional HDTC to determine two adjacent active vectors. The algorithm also uses the magnitude of the torque error and stator flux linkage position to select the switching time required for the two selected vectors. The selection of the switching time utilizes suggested table structure. The simulation results of the proposed algorithm show adequate dynamic torque performance and considerable torque ripples reduction as well as lower harmonic level as compared to HDTC. The simulation results of this part is supported by experimental work Index Terms: Active filter, direct torque control, electromagnetic Interference, field oriented control, harmonics passive filter, permanent magnet synchronous motor, torque ripples.