Rotor resistance adaptation for vector controlled induction motors considering deviations of the main inductance caused by the quadrature current

The vector control scheme for induction motors using the rotor flux reference frame is well known. To provide proper torque production, knowledge of the rotor time constant is essential. Many adaptation schemes have been presented using different paradigms. In this paper a scheme for rotor time constant adaptation is applied, which uses the difference between the measured and the calculated reactive power to calculate a correcting factor for the rotor time constant. Measurements have shown that the main inductance which is crucial to the calculation of the reactive power depends both on the magnetizing current and on the quadrature current. The adaptation scheme is therefore modified to consider this effect, improving the accuracy of torque production.