GB889518A - Constant frequency electric generator - Google Patents

Abstract

889,518. A.C. generators; adjustable cores. HAMBURGER FLUGZEUGBAU G.m.b.H. June 10, 1960 [June 12, 1959], No. 20408/60. Class 35. An electrical generator unit for producing an output of constant frequency when driven at a variable speed comprises a rotor with two axially-spaced field windings 2a, 2b producing magnetic fields which are phose-displaced by 90 degrees in relation to one another and supplied with current at frequency <SP>#</SP>trans from an exciter E. The stator of main generetor H is provided with two armature windings 7a, 7b also relatively displaced through 90 degrees. The exciter rotor is rigidly attached to the main driving-shaft and so rotates at the variable speed # rot while its field is rotated at the required output frequency <SP>#</SP>const. The rotating field may be produced by a permanent magnet " stator " 4 driven by a constant-speed drive HA, the exciter having a conical air-gap to permit regulation, or by an electromagnetic system fed by an auxiliary generator (Fig. 5, not shown) and producing a rotating field. In the latter case the exciter has two windings angularly displaced through 90 degrees, and the field windings of the main generator are not then phase displaced. The phase of the main output may be varied by rotating the exciter stator slightly. In either case the frequency of the excitation current supplied to the main generator field windings is <SP>#</SP>rot - <SP>#</SP>const. As the generator rotor rotates at frequency <SP>#</SP>rot the output frequency is therefore <SP>#</SP>const. A voltage regulator may be connected in the output circuit, feeding back to exciter E. A method of connecting two generator units together is also described (Fig. 6, not shown) employing a relay for interconnecting the output circuits when <SP>#</SP>rot exceeds a certain minimum, and a phase meter for equalizing the phases of the outputs. Specification 700,036 is referred to.