| 摘要 |
1384496 Controlling D.C. motors SIEMENS AG 12 June 1973 [13 June 1972] 27975/73 Heading H2J [Also in Division H3] An electric motor drive comprises a series/ parallel switching device 2 having connections for two D.C. sources 3, 4 and feeding a first circuit comprising a first D.C. motor 9, a first D.C. chopper 22 and a controllable rectifier 23 and a second circuit comprising a second D.C. motor 10 and a second chopper 24 and a rectifier element 27 connected between the circuits, the arrangement being such that when the controllable rectifier 23 is non-conductive the choppers 22, 24 can be controlled so that the motors 9 and 10 are in series and when the controllable rectifier 23 is conductive the choppers 22, 24 can be controlled so that the motors 9, 10 are in parallel. As described, the motors 9, 10 drive a single propeller of a water craft and may be controlled in three speed ranges by operation of series/parallel switches 13, 14, 15, thyristor 23 and thyristor choppers 22, 24. Each thyristor chopper (Fig. 7, not shown), comprises four parallel thyristors having a pair of commutation circuits, respectively operable at different loads, each comprising a bridge of four commutating thyristors and a capacitor. The choppers 22, 24 are preferably operated alternately. Further speed control is achieved by variation of the current in field windings 11, 12. Free-wheeling rectifiers 28, 29 are included. Fig. 10 shows an arrangement in which the free-wheeling diodes 58, 60 are returned to auxiliary terminals of the series/parallel switching device 2. Separate smoothing circuits 49, 65; 50, 66 are also included. |
