GB565934A - Improvements in and relating to dynamo-electric machine - Google Patents

Abstract

565,934. Dynamo-electric machines. BRITISH THOMSON-HOUSTON CO., Ltd. May 12, 1943, No. 7537. Convention date, May 13, 1942. [Class 35] To improve the amplification of a cross-field machine and its speed of response to changes in the control field excitation, the machine is so constructed that the magnetic circuit of the control field does not carry fluxes due to either primary or secondary armature reaction. For this purpose the armature core is formed in two portions 10, 11, magnetically insulated by a spacer 12 and each portion has a corresponding magnetically separate stator core. As shown in Fig. 1, the stator cores 22, 25 are supported by a frame 26 of non - magnetic material or of magnetic material of small cross-section. The control field exciting winding 20, Figs. 1 and 2, is arranged on the poles of the stator core 22 and primary armature reaction 24 in this core is compensated by polar windings 23 connected across the primary brushes 16, 17. Secondary armature reaction fluxes 27 are suppressed by polar windings 28 which also embrace the core 25 and carry the load current of the machine. In the modified construction shown in Figs. 4 and 5, the two polar sections of each stator core, as well as the two cores 35, 36 themselves, are magnetically insulated by non-magnetic shims 38, 39 and the sections of one core are displaced circumferentially 90 electrical degrees from the sections of the other core. By this means primary armature reaction flux 41, whilst having paths 42 in the sections of the stator core 36 is suppressed in the stator core 35 carrying the control field winding 33 by the non-magnetic shims 38. Secondary armature reaction 43 is suppressed in both stator cores in the core 36 by the non-magnetic shims 39, and in the core 35 by compensating windings 44 carrying the load current.