VSC-fed inside-out permanent magnet DC machines for wind generators

This paper estimates the performance of a conventional dc machine that is turned inside-out with the commutator replaced by switch-type semiconductors on the stator. The rotor is a permanent magnet design with trapezoidal radial flux density. Stator windings are full-pole pitch. The torque density for the inside-out dc machine is higher than other types of machines for the same equivalent cooling techniques. A Voltage Source Converter (VSC) method with shaft angle reference is used to coordinate the semiconductor switches. Interaction is shown between the design of the inside-out machine and operation of the ac-dc slot converters.