GB873898A - Constant frequency generator - Google Patents

Abstract

873,898. Induction generators; transformers. JACK & HEINTZ Inc. March 29, 1960 [April 6, 1959], No. 11027/60. Classes 35 and 38 (2). In an induction generator like that described in Specification 868,400 in which an induction generator is caused to produce a constant frequency at variable speed by supplying its rotor with slip frequency current, the static frequency changer and its controlling pulse-generator (identical with that shown in Fig. 7 of the previous case) are mounted within a hollow rotor shaft to avoid the use of slip-rings. The rotor winding 12 of the main generator 11 is fed through frequency changer 17 with current from the rotor winding 21 of a synchronous exciter generator 18 whose stator winding 20 may be energized at starting from a permanent magnet generator 22 through a rectifier and regulator 23. The pulse-generator 25 which controls the frequency changer is connected to the exciter winding 21 and also to a source 29 of reference frequency which is transmitted to the pulse generator through a rotating transformer 26. This transformer has fixed and rotating coil-sets 27, 28 which are arranged concentrically so that the frequency is not influenced by the rotation. If the regulator 23 requires it, an additional induction machine 33 may be provided which generates a signal current proportional to the exciter voltage. The rotor windings 34 of this machine are connected in reverse phase rotation to the exciter winding 21, and the stator winding 35 is connected across a choke in the regulator 23 to provide the desired current. The hollow rotor comprises concentric tubes 83, 95 between which are located the components 1-6 and 40, 42 of the frequency changer. Cooling oil is circulated through this space and also through stator passages 78. A synchronous condenser 15 may be connected to the machine output winding 14.