Improving dynamics of repetitive control based current harmonic mitigation in inverter-fed permanent magnet synchronous machines with nonlinear magnetics

Abstract

Inverter nonlinearities and machine spatial harmonics yield unwanted machine current harmonics causing noise, vibration, additional losses and torque ripples. In this paper the dynamics of a repetitive control based mitigation method are analysed. The proposed scheme identifies voltage errors and compensates their effects online for interior permanent magnet synchronous machines with nonlinear magnetics. It requires no additional sensors and only fundamental machine model parameters. Test bench measurements of maximal torque inversion and variable speed operation proof the fast convergence of the developed algorithm. Current harmonic mitigation is reached after several electric periods and in the time range of 100 ms during typical operational conditions. The functional principle is transferable to other machine types or grid applications enabling fast and precise mitigation of current harmonics in a wide field of applications.