Discrete time sliding mode observers for sensorless vector control of PMSM

This paper proposes a new discrete-time sensor-less algorithm for current vector control of permanent magnet synchronous machines (PMSM). A discrete-time sliding mode current observer is proposed as well as the sliding and convergence conditions of the sliding mode are established. Then, an electric speed identification is proposed by using Lyapunov´s direct method via a electromotive force (EMF) observer in the discrete-time domain. In addition, the stability of the proposed discrete-time observers is presented, and from them, the conditions to ensure convergence are derived. Therefore, the rotor position is identified directly of the observed EMF. Finally, experimental results are given to support the theoretical analysis as well as to demonstrate the good performance of the proposed discrete-time sensorless algorithm.