Quantization Error Decoupling in Vector-tracking Observer for High-speed Control of Permanent Magnet Synchronous Motors with Low-resolution Encoders

This paper addresses the challenge of using low-resolution encoders (LREs) for high-speed control of the permanent magnet synchronous motor (PMSM), while high-resolution encoders raise cost and reliability concerns. Although previous studies have reported the quantization error caused by LREs, their behavior at high speeds has not been fully explored. This research analyzes the critical frequency bands in which LREs affect the control performance in the discrete domain. Based on this analysis, we propose a novel position observer that decouples the quantization errors, significantly enhancing the observation accuracy from LREs, and thus reducing the torque ripple. Simulation and experimental results confirm the effectiveness of the proposed method.