Optimization Method to Maximize Efficiency Map of a Drive Motor with Electrical Winding Changeover Technique for Hybrid EV

The electrical winding changeover technique (EWCT) in hybrid electric vehicles will become key to improving the efficiency maps over the whole operating range in the future. This technique can enhance a flux weakening control and reduce a back electromotive force at high speed operation by changing the effective winding turn number. It can increase the efficiency at high speed by a reduction of winding resistance. In this paper, the motor is operated with two step modes, where the winding turn number of the first step mode is twice that of the second step mode. Each step mode is addressed in terms of torque production, back-EMF, voltage and efficiency. Finally, an optimal design of the interior permanent magnet synchronous motor with EWCT is implemented for maximizing the efficiency map based on finite element analysis.