Inverter-driven synchronous motors for constant power

Inverter-driven synchronous motors are widely used in high-performance variable-speed drive systems. In this article, the effects of machine parameters and the operating characteristics with respect to several types of synchronous motors-which include synchronous reluctance motors, surface permanent magnet synchronous motors, and interior permanent magnet synchronous motors-are examined. The optimum current vector producing the maximum output power at any speed is derived considering both current and voltage constraints.