A Novel Pole-changing Method with a Multiple Three-phase Inverter

This paper presents a new pole-changing method with a multiple three-phase inverter. Since the number of controllable current phases is much larger than that of conventional methods, a higher winding factor can be obtained in both high and low pole driving modes. To evaluate the magnetic characteristics of the present method, magnetomotive force analysis is conducted based on Fourier series expansion and finite element method (FEM). Moreover, mutual inductance is compared between high and low pole driving using FEM. To validate the effectiveness, an efficiency map is evaluated by using a prototype induction motor.