A Novel Online Parameter Estimation Method for Indirect Field Oriented Induction Motor Drives

This paper presents a novel online parameter estimation method to overcome the negative influence of parameter mismatch on the field orientation and then on the performance of the indirect field oriented induction motor drives. This method allows for parallel estimation of the rotor resistance and the mutual inductance, which tend to deviate from their nominal values resulting from changes in temperature and flux level. In the case of electrical vehicles or wind power generators, the parameter deviation degrades the drive performance in two ways: calculation of the current reference from the torque command issued by the power control unit and calculation of the slip frequency for the indirect field orientation. Moreover, the mutual inductance estimation is more critical in these wide speed range applications than in general industry field. This proposed estimation method is implemented through a model reference adaptive system about the rotor flux. The reference model comes from two sliding-mode observers (SMOs): a terminal SMO and a linear SMO, implemented in series. The adjustable model is undertaken by the current model of rotor flux. The analysis and design presented in this paper are confirmed both through numerical simulation and experiments.