Performance of Feed Forward Current Regulators for Field Oriented Induction Machine Controllers

In order to achieve instantaneous control of induction motor torque using field orientation techniques, it is necessary that the phase currents be controlled to maintain precise instantaneous relationships. Failure to do so results in a noticeable degradation in torque response. Most of the currently used approaches to achieve this control employ classical control strategies which are only correct for steady state conditions. This paper develops a modern control theory approach which circumvents these limitations. The approach uses a state variable feedback control model of the field oriented induction machine. This state variable controller is shown to be intrinsically more robust than PI regulators. The paper includes experimental verification of the performance of this state variable control strategy in achieving current loop performance and torque control at high operating speeds.