Fast search controllers for efficiency maximization of induction motor drives based on DC link power measurement

This paper presents three new techniques for the efficiency optimization of vector controlled induction motor drives. The flux producing current is controlled till the power at the DC link is minimum. Of the three techniques, the first method is based on the power-flux gradient and the second method reduces the flux producing current in a smooth manner till the DC link power shows an upward trend. The third technique combines loss model and search approaches in a unique manner to propose a hybrid method, where the first estimate is from loss model approach and the subsequent adjustment of the flux is through the search technique. All three methods are faster than the available methods. Also smooth control of the flux offers excellent dynamic performance. A comparative assessment shows that the hybrid method is the best, even if only a rough estimation of the induction motor parameters are available. The close agreement between the simulation and the experimental results confirms the validity and usefulness of the proposed techniques.