An efficiency-optimization controller for induction motor drives

When working close to their nominal operating point, induction motors are high-efficiency machines. However, at low load, efficiency is greatly reduced when magnetization flux is maintained at nominal value. Therefore, it is necessary to adjust the flux level according to the load, so as to decrease iron and copper losses. This paper deals with a field-oriented scheme for induction motor drives leading to efficiency optimization. It is based on optimal power factor tracking by adjusting magnetization current component with to respect the torque current component. Simulation results are presented to highlight the feasibility and validity of the proposed method