Improvements in or relating to alternators having insulated stator and rotor windings and to transmission systems using such alternators

摘要

1,030,493. Alternators; control of several A.C. motors. NATIONAL RESEARCH DEVELOPMENT CORPORATION. May 18, 1962 [May 25, 1961], No. 18900/61. Headings H2A and H2J. In an alternator having a wound stator and rotor, the rotor winding comprising a plurality of coil sets #... 6# so arranged as to generate a travelling magnetic field if polyphase energized yet which are energized through slip-rings by direct currents which are appropriate to the particular values of polyphase currents at a particular instant of time so that the field generated is stationary with respect to the rotor, the pole number of the rotor winding is adjustable under the control of switching arrangements SW which differently interconnect the sets of coils all of which are continuously energized, and the values of the direct currents are so chosen that that in certain sets is the same for each pole number whereby such sets are fed in parallel and the number of slip-rings S1 . . . S10 necessary is reduced. As shown, ten slip-rings are required by connecting in parallel the sets 20 and 60, and 30 and 5#, but where a 3-wire supply is available, Fig. 5, not shown, the number may be further reduced to seven. Fig. 4 shows the switching arrangement of the Fig. 3 embodiment, and the stator winding may have the same configuration as the rotor winding and further switching arrangements whereby the pole numbers of the two windings are adjusted in sympathy to vary the output frequency. The stator winding alternatively may comprise coil groups feeding via several outlets an adjustable frequency supply to a plurality of pole changing traction induction motors of the type disclosed in Specification 978,211. In Figs. 7 and 8 two alternators supply phase-displaced adjustablefrequency currents to such motors.