Characteristics of an integrated motor controlled independently by multi-inverters to achieve high efficiency and a wide speed range

For electric vehicles, motor operation is achieved by using a highly efficient variable-speed drive. In this paper, we describe the characteristics of a novel motor capable of pole and phase changes; it is a high-performance motor because it has multiple windings combined with multi-inverters. The pole changes will allow the motor to operate with a large torque at a low speed by using a small number of poles; the motor can operate at high efficiency at high speeds by using a large number of poles. The motor had three groups of three-phase windings consisting of 18 coils. One group of the three-phase windings was consisted of 6 coils. Three three-phase inverters that connected the three groups of three-phase windings directly controlled the current phase of each winding, which helped change the number of poles and phases. The results of our analyses confirmed that the motor produced a large torque at a low speed of 3000 rpm for the eight-pole mode, and operated with a high efficiency of approximately 96% at a high speed of 6000 rpm for the four-pole mode.