Sliding-Mode Control for Speed Sensorless Induction Machine Drive Using an Adaptive Nonlinear Rotor Flux Observer

This paper presents a new adaptive rotor flux observer for speed sensorless induction motor (IM) drives which provides the rotor speed, stator and rotor resistances estimations simultaneously. The rotor speed and rotor flux controllers are designed based on combination of input-output feedback linearizing, sliding-mode (SM) control and linear quadratic (LQ) feedback control. It is shown that the composite rotor speed and rotor flux controllers in combination with adaptive flux observer guarantee the system stability and robustness against the parameter variations and external load disturbance under system persistency of excitation (PE) condition. The PE condition is satisfied if a low frequency AC signal is superimposed to the rotor reference flux under motor loading operating. The validity of the proposed method is supported by simulation and experimental results