Adaptive Harmonic Tracking Based Speed Ripple Reduction Method for Permanent Magnet Synchronous Motor Drives

In permanent magnet synchronous motor (PMSM) drive systems, nonideal factors induce periodic speed ripples. Conventional harmonic injection–based speed ripple reduction methods exhibit significant sensitivity to speed-loop bandwidth limitations and speed sensor sampling delays. According to the phase delay modeling in velocimetry and the equivalent cutoff frequency of the drive system, theoretical boundaries for the unstable operating region of harmonic injection–based methods are established. In this article, a novel speed ripple reduction method based on adaptive harmonic tracking is proposed for PMSM drives. The proposed method utilizes the saturation characteristics of spectral analysis theory under unstable states to adaptively correct the injected harmonic modes. The injected compensation current realizes adaptive tracking of speed ripple even in the presence of unmodeled disturbances. The effectiveness of the proposed method is verified by experiments on a 2.2-kW PMSM drive platform.