Rotor Position Estimation Method for PMSM Based on Improved Sliding Mode Observer

To address the problems of high-frequency chattering and phase delay in traditional sliding mode observer, an improved sliding mode observer combining sinusoidal switching function with back electromotive force observer is proposed. Firstly, the sinusoidal switching function is employed as a substitute for the conventional sign function, thereby effectively suppressing the chattering problem. Secondly, an adaptive observer is constructed to process the equivalent back electromotive force, which reduces the harmonic content and avoids the phase delay issue that arises from the use of a low-pass filter. Finally, the experimental analysis is carried out with 1kW surface-mounted permanent magnet synchronous motor. Experimental findings indicate the improved sliding mode observer effectively addresses concerns related to high-frequency chattering, phase delay, and harmonic content in the equivalent back electromotive force. This confirms the practicality and credibility of the proposed improved sliding mode observer.