Fast efficiency optimization techniques for the indirect vector-controlled induction motor drives

This paper presents two simple and very useful techniques for the efficiency optimization of the indirect vector-controlled induction motor drives. In the synchronously rotating reference frame the flux-producing current is controlled until the power at the DC link is minimum. Of the two techniques, the first method controls the flux-producing current in a regular and smooth manner. The second technique combines loss model and search approaches in a unique way to propose a hybrid method, where the first estimate is from the loss model approach and the subsequent adjustment of the flux is through the search technique. Both the algorithms are simple, easily realizable, and offer fast convergence. Also, smooth control of the flux offers excellent dynamic performance. A comparative assessment shows that the hybrid method is the best, even if an approximate equivalent circuit for the induction motor is used for the analysis and optimization of the losses. The close agreement between the simulation and the experimental results confirms the validity and usefulness of the proposed techniques.