Field-oriented control of an induction motor with robust on-line tuning of its parameters

This paper proposes new torque control of an induction motor, which is robust against the variation of the primary resistance and adaptable to the leakage inductance, the mutual inductance and the secondary time constant. The control is based on a flux simulator. The simulator employs a rotor current model so as not to be affected by the variation of the primary resistance, but uses the mutual inductance and the secondary time constant values to estimate the flux. Their parameter mismatches make transient phenomena in flux and torque responses worse. In order to compensate for degradation of the responses, an identifier of them is introduced into the system. The identifier is perfectly robust against the variation of the primary resistance because it is based on the instantaneous reactive power of the induction motor. In addition to that, the leakage inductance identifier is also introduced to achieve perfect compensation which is robust against other parameters. To verify the feasibility of this technique, some digital simulations and experimental tests were conducted on the basis of theoretical consideration. The results prove excellent characteristics, which confirm the validity of the proposed scheme