Abstract
The torque-speed characteristics of an interior magnet brushless motor are compared with particular reference to the flux-weakening performance for EV/HEV applications, when it is operated in brushless AC (BLAC) mode, with 3-phase, sinusoidal current waveforms, and in brushless DC (BLDC) mode with both 2-phase, 120° conduction and 3-phase, 180° conduction rectangular current waveforms. It is shown that while 2-phase, 120° BLDC operation results in the highest torque capability for the same peak current and BLAC operation results in the highest specific torque per rms current when operating below the base-speed, 3-phase, 180° BLDC operation generally results in the best performance in the flux-weakening region.
