A new method for rotor time constant tuning in indirect field oriented control

The authors investigate and implement a novel model reference adaptive controller for correction of the rotor time constant used in the calculation of the slip frequency in indirect field oriented control of induction machines. The implementation of the controller is based on the machine air gap flux which is measured by detecting the third harmonic component of the stator pulse voltages. The proposed adaptive controller depends only on a single, easily measurable machine parameter estimate, i.e., the magnetizing inductance. A correction strategy to compensate for changes of the magnetizing inductance when changes in the air gap flux level occur is also proposed. This strategy is based on a function that relates the value of this inductance to the amplitude of the third harmonic stator voltage component. Verification of the validity and feasibility of the proposed technique is obtained from simulation and experimental results