Maximum torque control of an induction machine in the field weakening region

In this paper, a new approach to the induction machine control that ensures the production of maximum torque per ampere over the entire field weakening region is presented. Considering the limitations of voltage and current, the optimal current condition for yielding the maximum torque is obtained. Also, since the onset of the field weakening operation is automatically adjusted according to the flux level, the current limit and the voltage limit, smooth and precise transition can be obtained. The proposed scheme is verified through simulation and experiment with a 5-hp laboratory induction motor drive system