Sensor less field oriented control of an induction motor using an instantaneous slip frequency estimation method

A speed-sensor-less torque-control scheme for an induction motor using a current-source inverter is proposed. The method is based on field-oriented control; the instantaneous slip frequency is estimated from terminal voltages and currents of the motor. An improved instantaneous-slip-frequency estimation method and a rotor-speed estimation method are described. The incremental system transfer function around operating points is used to determine the optimum values of the estimator gains and the torque controller gains, which are needed in the analysis. Experimental and simulation results that confirm the validity of the approach are given.<>