GB673691A - Improvements relating to dynamo-electric machines - Google Patents

Abstract

673,691. Winding layouts for dynamoelectric machines. BRITISH THOMSONHOUSTON CO., Ltd., CLARK, L. J., MAGGS, A. H., and CHOUDHURY, S. U. A. July 4, 1950 [Aug. 5, 1949], No. 20379/49. Class 35. The winding of a dynamo-electric machine is given a sinusoidal distribution by making the pitch of the coils two-thirds of the pole-pitch, by making the number of coils per pole-pair per phase equal to (the nearest integer to) two-thirds the number of slots per pole-pair, and making the number of turns in each coil approximately equal to sin (#/3 Œ α), where " a " is the electrical angle between the axes of the coil and its pole-phase group. The single-phase winding shown in Fig. 3 has 24 slots per pole-pair, the pole groups 1 to 8 and 13 to 20 being similarly varied, as regards coil numbers, in accordance with the invention. Thus, the conductors in coils 1-9 and 8-16 which are the first and last coils of one pole group and coils 13-21 and 20-4, which are the first and last coils of the other group, have only a few conductors, i.e. proportional to sin 7.5 degrees. The coils towards the centre of each group have larger numbers of conductors, i.e. proportional to the sines of larger angles up to 52.5 degrees. In polyphase windings, each phase is equally divided into two consecutively wound sections superimposed in the same slots so that the end portions of each section may be symmetrically interwoven by inserting all the left or right hand coil sides into the slots first. Fig. 5 shows one form of three-phase winding in which the coils having numbers of turns increasing with " α " are wound in one direction and those having numbers of turns decreasing with " α " are wound in the other section, the sections being interconnected at points AX, BX, CX. In an alternative arrangement, all the coils of one polarity in each phase are wound in one section and the coils of the other polarity in the other section.