An Improved DPCC Based on a Cascade Extended State Observer With Notch Filter for PMSM Current Disturbance Suppression

The Permanent Magnet Synchronous Motor (PMSM) is subjected to various disturbances during operation. Traditional deadbeat predictive current control (DPCC) based on extended state observer (ESO) with resonant controllers tends to amplify disturbances near resonant frequencies, particularly introducing high-frequency noise under high-order harmonics, which degrades the control accuracy. To address this issue, a cascade ESO with notch filters (NFESO) is proposed in this paper. The proposed method employs a two-step disturbance estimation strategy: in the first step, the direct current (DC) disturbance ESO is designed to achieve accurate observation of DC disturbance; in the second step, the harmonic ESO with notch filter is designed to estimate periodic disturbances at specific frequencies. By integrating the notch filter, NFESO enables the precise estimation of both DC and harmonic disturbances while avoiding the disturbance amplification issue. Moreover, the cascade structure utilizes the total disturbance estimate from the previous ESO as the input for the next cascade ESO, effectively avoiding the degradation of disturbance estimation performance typically seen in the traditional cascade structure. At the same time, it decouples the interactions between different disturbance estimations, making stability analysis more intuitive and reducing the complexity of parameter tuning. Experimental results demonstrate the effectiveness of the proposed method.