Improved Resonant ESO-Based Sampling Delay Error Suppression Method for PMSM Drives Using a Single DC-Link Current Sensor

In single DC-link current sensor control for permanent magnet synchronous motor drives, a sampling delay error (SDE) inherently exists due to the discrepancy between the sampling instants of the reconstructed phase currents and the ideal phase currents, which degrades current accuracy. The method of suppressing the SDE by calculating the online current slopes not only requires intensive computation but also depends on the accuracy of system parameters and the durations of voltage vectors. This article analytically demonstrates that the SDE exhibits a periodic disturbance correlated with the stator electrical frequency. Accordingly, an SDE suppression method based on a resonant extended state observer (RESO) is proposed without the need to calculate the current slopes. To address the resonance phenomenon in the conventional quasi-RESO (QRESO) caused by the coupling between disturbance attenuation capability and observer bandwidth, an improved RESO is proposed by redesigning QRESO while considering the quality factor that characterizes the frequency selection capability. Experimental results verify the feasibility and effectiveness of the proposed method.