An Improved Sliding Mode Observer for Position Sensorless Synchronous Reluctance Motor Drives

To improve the position estimation for synchronous reluctance motor (SynRM) drives, an new full-order sliding mode observer (SMO) designed by using sinusoidal saturation function is presented. Firstly, the full-order SMO taking the extended electromotive force (EEMF) and the stator current as the state variables is built. Then, we would use a quadrature phase-locked loop (PLL) which can track the rotor position based on EEMF estimates. In view of reducing chattering phenomenon in traditional SMO, the sinusoidal saturation function is utilized to stand in for the switching function. Finally, according to experiments on a 3-kW SynRM drive, the proposed method is verified.