The sensorless control of IPMSM based on improved sliding-mode observer

The fundamental excitation methods are widely used to implement the sensorless control of the interior permanent-magnet synchronous motors (IPMSM) in the medium to high speed regions. This paper utilizes the sliding-mode observer (SMO) to extract the extended back electromotive force (EMF) components of the IPMSM which contains the position related information. The stability of the SMO is verified by the Lyapunov function. A sigmoid function substituting the signum function is used to reduce the chattering, consequently both low-pass filter and phase compensator in conventional SMO schemes are eliminated. To remove the noisy parts from the estimated extended EMF components further, the adaptive line enhancer (ALE) is utilized to filter the signal without introducing any phase delay. The phase-locked loop (PLL) type estimator is proposed instead of the inverse tangent method, providing better performance of mitigating the oscillations caused by the disturbances. Effectiveness of the proposed sensorless control scheme is verified via simulation results.