| 摘要 |
974,226. Synchronous motors. NATIONAL RESEARCH DEVELOPMENT CORPORATION. May 16, 1961 [June 8, 1960], No. 20083/60. Heading H2A. The negative-sequence impedance in a singlephase synchronous motor is compensated by an auxiliary rotating magnetic field produced by an additional three-phase rotor winding 1, 2, 3 energized at double frequency from an exciter 20 to produce a rotating field in opposition to that produced by the negative-sequence current of the single-phase supply. In the salient-pole type shown, the rotor field windings 21, 22, 23, 24 are fed in the usual way from a self-exciting D.C. exciter 30 on the same shaft. The negative-sequence windings 1, 2, 3 are pole-face windings which may be shorted by switch 11 for induction starting prior to connection to the double-frequency exciter 20 for normal running. A separate stator winding 39 is provided for starting. A cylindrical-rotor embodiment is described in which a single three-phase winding is used for the D.C. and reverse-sequence excitations. The double-frequency exciter may be on the same shaft or separately driven. |
