The synthesis of a high gain observer for the on-line estimation of the rotor fluxes, the motor speed and the load torque of the induction motor from the current and voltage measurements is presented. The synthesis of the observer is preceded by an observability analysis of the induction motor leading thereby to a sufficient condition. The obtained condition is discussed and it is shown that it is generally satisfied in practice when considering the usual operating conditions of the motor. Of particular interest, an implementation procedure is proposed to deal with the observation singularities. The proposed observer has been validated in simulation using the reference trajectories of a realistic proposed benchmark where the induction motor model remains in an unobservable region and not just go across.

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