New variable gain super-twisting sliding mode observer for sensorless vector control of nonsinusoidal back-EMF PMSM

•A new discrete-time super-twisting SM observer with variable gains is proposed.•Variable gains can mitigate adequately the residual chattering.•The discrete-time stability analysis demonstrates that the observer is stable.•The method is implemented in an experimental platform with a fixed point DSP.•Experimental results verify the effectiveness of the proposed observer.

This paper presents a new discrete-time super-twisting sliding mode observer with variable gains for sensorless nonsinusoidal vector control of permanent magnet synchronous motors. This observer is adopted to estimate the back electromotive forces (back-EMF) that are required for the rotor speed estimation and for the nonsinusoidal vector control. In addition, their gains are time-varying to minimize the chattering. So, they are adjusted based on internal states of the super-twisting algorithm. The stability analysis is investigated from the Lyapunov theory for discrete-time systems. Finally, simulation and experimental results are presented to demonstrate the good performance and the effectiveness of the proposed observer.