Power converter sizing considerations for a doubly-fed machine propulsion drive

Doubly-fed machines (DFM) can be used to make variable speed drives (VSD) that not only provide full shaft speed control but also avoid the need for a dc electrical bus capable of providing full mechanical shaft power. This makes the DFM attractive for any VSD application where the primary power source is ac. This paper explores the design and control requirements for the DFM rotor power electronics in full-speedrange VSD applications, including propulsion drives. Trade-offs are examined for power electronics sizing versus transient settling characteristics.