A High Precision Observer Using a Full-Range Harmonics Suppression Scheme for High-Speed Permanent Magnet Synchronous Motor

The sensorless control of permanent magnet synchronous motors (PMSMs) using a sliding mode observer (SMO) to extract the back electromotive force(BEMF) is susceptible to various disturbances such as modulation algorithms, inverter switching characteristics, and current sampling errors. These factors contribute to the presence of significant low and high frequency harmonics component in the stator current, which in turn deteriorates the accuracy of the speed and position estimation. These harmonics not only affect the performance of the SMO but also hinder the overall control system’s dynamic response. To address these challenges, this paper presents a high-precision harmonics suppression scheme based on a full-frequency domain approach. The proposed solution involves a series of adaptive comb filters (SACF) to effectively suppress low-frequency harmonics, thereby eliminating phase delays and improving BEMF estimation. Additionally, an LC filter combined with a frequency adaptive notch filter (FANF) is employed to mitigate high-frequency harmonics, which are particularly problematic due to their interaction with the sampling process. Experimental results validate the practicality and effectiveness of this proposed strategy. The proposed method significantly reduces harmonic components in the motor, leading to notable improvements in the dynamic performance of the control system and enhanced accuracy of speed and position estimation.