Second Order Generalized Integrator Filtering For Enhanced Sliding Mode Observer with Fuzzy Logic Switching Function

Traditional Sliding Mode Observers (SMO) in sensorless control of Permanent Magnet Synchronous Motors (PMSM) encounter issues such as chattering and phase delay, resulting in significant discrepancies between the estimated and actual rotor speed and position. Therefore, this paper proposes an improved SMO based on a Fuzzy Logic Controller (FLC) and an Open-Loop Frequency Estimation-based Second-Order Generalized Integrator Frequency Adaptive Filter (OLFE-SOGI) structure. The FLC implements an SMO with a selfadjusting shape factor for the sigmoid function. This strategy accelerates the convergence speed of the SMO while reducing chattering caused by the boundary layer thickness. Additionally, to mitigate the adverse effects brought by lowpass filters (LPF), the OLFE-SOGI is employed to accurately extract the back electromotive force (back-EMF) without phase delay and effectively eliminate high-order harmonic components. Simulation results verify the effectiveness and accuracy of the proposed strategy.