Torque Ripple Reduction in a Traction IPMSM With Resistance Asymmetry Using an Adaptive PIR Current Controller

Abstract

Unbalanced three-phase currents are drawn using the conventional current controllers in the electric drive system of a permanent magnet synchronous machine (PMSM) with asymmetric phases. Consequently, the negative sequence current appears, which causes the torque ripple in the PMSM. The torque ripple yields the noise and mechanical vibrations in the PMSM drive, reducing the reliability, efficiency, and life span of the machine. The conventional proportional-integral (PI) current controller in a PMSM drive is unable to mitigate the torque ripple for the PMSM with asymmetric phases due to its incapability in dealing with the unbalanced sinusoidal input stator currents. To address this limitation, this manuscript presents an adaptive PI resonant (PIR) current controller, which comprises of a PI controller in conjunction with the resonant controller and harmonic compensation terms in the inner current control loop of an interior PMSM (IPMSM) drive with resistance asymmetry. The harmonic-based resonant controller part of the PIR controller takes care of the harmonic compensation. The saturation of the IPMSM and time harmonics are considered during the simulation studies to mimic the actual behavior of a motor drive system. A significant reduction in torque ripple using the proposed PIR current controller compared to a conventional PI current controller is demonstrated for a 100 kW traction IPMSM with phase asymmetry.