A new approach to induction machine flux and speed observer with on-line rotor time constant estimation

This paper presents flux and speed estimation with on-line rotor time constant estimation for an indirect field oriented induction motor drive system using sliding mode technique. A closed loop flux observer based on the current estimation error is constructed. A unique feature of the proposed observer is that, the proposed current observer includes a sliding mode function, which is derivative of the flux. Therefore, when the estimated current converges to the measured one, the sliding mode function is integrated to calculate the flux. The speed and rotor time constant can then be calculated from the sliding mode function and the estimated flux. Simulation and experimental results for the flux and speed estimation of the machine are presented to validate the proposed algorithm