Patent ID: 6051953
Filing Date: 2000-04-18
Classification: H02K

Abstract:
A three phase AC motor which rotates at the synchronous speed corresponding to the frequency of the AC input to its main stator winding and the number of poles of this winding, by using an internal excitation system for providing an adjustable DC field current without the need for brushes and separate exciter machine: said excitation system comprising: (1) an auxiliary winding on the stator, this auxiliary winding being wound for a different number of poles from the main winding; (2) another auxiliary winding on the rotor wound for the same number of poles as the auxiliary winding on the stator, in which AC voltages are induced according to the input to the stator auxiliary winding and the speed of rotation; (3) a diode rectifier which converts the AC from the rotor auxiliary winding into DC; and (4) a main DC field winding on the rotor, wound for the same number of poles as the main stator winding, which receives the DC excitation from the said diode rectifier: wherein the number of poles of the main and auxiliary circuits of the stator and rotor arc chosen in such way as to eliminate magnetic coupling between the main and auxiliary windings.