GB1340860A - Linear induction motor stator - Google Patents

Abstract

1340860 Linear motors TRACKED HOVERCRAFT Ltd 19 April 1971 [27 Feb 1970] 9730/70 Heading H2A In a linear induction motor particularly for a tracked gas-cushion vehicle wherein the primary member comprises a magnetic core having teeth spaced longitudinally of the motor and carrying a polyphase winding, the winding comprises for each phase and pole pair, a plurality of coil groups arranged in at least two layers, each group consisting of at least two concentric coils, the coils being planar and those in each layer lying in a common plane. Figs. 1 and 2 show a motor in which the primary member has a longitudinally-laminated, toothed core 15 embraced by a transversely laminated U-shaped core 10, the winding being on core 15 and comprising two layers 16, 17, each coil group consisting of a pair of concentric coils 5, 6. Consecutive coil groups in each layer belong to different phases in rotation and the groups in the two layers belonging to a given phase are offset by six teeth 4 with respect to each other. Coil groups of each phase are interconnected either in series, series-parallel or parallel and the three windings so formed connected in star or delta. In an alternative winding arrangement the coil groups in the layers are off-set by a further tooth from the relationship shown in Fig. 2. Fig. 5 shows a further winding consisting of four layers, the first two layers 16, 17 being arranged as in Fig. 2, the third layer 18 being offset by a further tooth and the fourth layer 19 being off-set by one tooth with respect to layer 16. Each coil group in a two-layer winding may consist of three coils, Fig. 6 (not shown), and in the arrangement shown in Fig. 2, the outer coils in each group may have half the number of turns of the inner coils and share slots with the outer coils of adjacent groups, Fig. 8 (not shown). In a still further winding arrangement, Figs. 9 and 10 (not shown), each layer of a three-layer winding consists of coil groups of the same phase, one layer for each phase. The primary member shown in Fig. 1 may be modified by the omission of the core 10 or, as shown in Fig. 11, the coils 5, 6 may embrace the central limbs of stacks 22 of transverse E- shaped laminations 21, the stacks being spaced longitudinally of the motor. The further core construction shown in Fig. 13 comprises two longitudinally-laminated, toothed cores 15, each constructed and wound similarly to the core 15 in Fig. 1, and bridged at intervals by stacks 27 of transverse laminations 26. In all the embodiments described means may be provided for changing the connections between the coil groups so as to vary the number of poles.