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The conventional sliding mode observer (SMO)-based sensorless control methods for permanent magnet synchronous motors (PMSMs) exhibit critical problems of sensitivity to DC offset interference caused by zero-drift in sampling circuits and limited dynamic response of quadrature phase-locked loops (QPLLs). To address these issues, a DC offset rejection sensorless control method for PMSMs based on improved SMO and multi-interval double-cost-function finite-position-set phase-locked loop (MDCF-FPS-PLL) is proposed. Firstly, an improved SMO is designed by adding the second-order extended-state model of estimated back-electromotive forces (BEMFs), which effectively eliminates steady-state rotor position estimation errors and enhances the capability of suppressing DC offset interference. Secondly, a Newton iteration method-based FPS-PLL with double-cost-function is introduced to replace QPLL. The rotor position estimation error during dynamic transients can be effectively reduced and the parameter tuning can be avoided. Moreover, the MDCF-FPS-PLL significantly reduces computational burden without compromising theoretical phase-locking accuracy. Compared with conventional SMO based sensorless control methods, the proposed method demonstrates superior performance in decreasing rotor position estimation errors for both transient and steady-state operations. Finally, the effectiveness and superiority of this method are validated through experiments.
Wu et al. (Tue,) studied this question.