Improvements in and relating to self-compensating brushless alternators.

摘要

Disclosed is a self-excited alternator of the brushless type, having a rotating field which is excited by an alternating current exciter whose rotating armature is mounted to rotate with the rotating field winding of the alternator and is permanently connected to the field winding of the alternator via field rectifier means also mounted to rotate with the field winding. The exciter has an exciter stator primary winding (FX) and a rotary exciter secondary winding (U) connected via rotary field rectifier (D1) means to the rotary main field winding (FM) of the alternator. The primary excitation direct current for the exciter is derived, via magnetic coupling, from a rotary auxiliary magnetic field produced by a feedback winding (FF) connected in series with the main field winding and mounted to rotate herewith. A common magnetic circuit is used for coupling the rotary feedback winding with a auxiliary stator secondary winding and for coupling the exciter primary and secondary windings. The common magnetic circuit comprises a common stator core on which the exciter primary winding (FX) and the auxiliary secondary winding (V) are provided and a common rotor core on which the exciter secondary winding (U) and the feedback winding (FF) are provided. The rotor core is so shaped and the feedback winding is so provided thereon that in operation a pole group having either K or NK feedback pole pairs is formed with poles uniformly disposed around the rotor core. The stator core is so shaped and the exciter winding or windings are so provided thereon that in operation a pole group having either NK or K exciter pole pairs are formed with poles uniformly disposed around the stator core, the ratio of feedback pole pairs to exciter pole pairs being either K to NK or NK to K, where K is any number and N is an even number. Either the feed back winding or the exciter primary winding, as the case may be, for forming the pole group having K pole pairs comprise one or more first winding portions wound for generating the poles of that group whereby, with rotation of the rotor core relative to the stator core, the nett change of magnetic flux linking with each first winding portion and due to the pole group having NK pole pairs is substantially zero.