High-Bandwidth Harmonics-Suppressed Dynamic Phase-Synchronized Adaptive Notch Observer for High-Frequency Injection Based Sensorless Drive

In high-frequency (HF) injection based saliency tracking, harmonic errors arise from non-idealities in interior permanent magnet synchronous motor (IPMSM) and inverter. Conventionally, achieving both high-bandwidth observation and reduced low-order harmonics presents an inherent trade-off. Adaptive notch filter (ANF), featuring harmonic suppression characteristic without affecting the target signal, is gaining increasing attention. In this paper, the saliency tracking bandwidth-constrained divergence phenomenon in conventional ANF based harmonic suppression is firstly revealed. Due to the inherent closed-loop nature in saliency tracking, there is inevitable phase misalignment between detection and compensation, which could lead to high risk of divergence in harmonic suppression, especially in low-speed and high bandwidth observation. Subsequently, a novel dynamic phase-synchronized adaptive notch observer (DPS-ANO) is proposed, which has the unique ability to counteract the closed-loop effect. The convergence boundary is expanded and full-order harmonics can be suppressed under high-bandwidth observation at low-speed. The convergence boundary is analytically proven and the enhancements of the proposed harmonic suppression method are verified with experiments.