Induction motor winding commutation with direct field oriented control for wide constant power range operation

This paper deals with a direct vector control induction motor drive, that, in order to get wide constant power range, employs an induction motor with winding commutation. The stator windings are series connected at low speed and parallel connected at high speed, thus a constant power region of 1:n is reached from the point of view of the whole drive, while 1:(n/2) constant power region is reached from the point of view of the motor. The motor characteristics, both with series and parallel connected windings, are analyzed and experimentally verified. The winding changeover procedure, with direct field oriented control, is presented with experimental results