| 摘要 |
719,813. Control of motors. GENERAL ELECTRIC CO., Ltd., and FRIEDLANDER, E. S. April 9, 1953 [April 9, 1952], No. 9092/52. Class 38(3) [Also in Group XXXV] In a traction system, a transformer 13 is connected to a single-phase source and supplies a phase converter machine 15 having star-connected primary windings adapted to produce a threephase output. A direct-current generator 16 is driven by the machine 15 and supplies a motor 20 which, in turn, drives a frequency converter 21 having its stator windings connected to the output circuit of the phase converter. The output of the machine 21, the frequency of which is dependent upon the speed and direction of the motor 20, is supplied to traction motors 25 of the polyphase induction type. The field excitation of the generator 16 is controlled by a double potentiometer 31, 32, so that the generator can be varied from full excitation in one sense through zero to full excitation in the opposite sense by movement of an arm 34. The machine 15 is started from the single-phase supply by connecting a resistor 36 between a secondary winding terminal of the trans-, former 13 and one of the stator terminals of the phase converter, whilst another of the stator terminals is connected through two of the stator windings of the machine 21 to the same terminal of the secondary winding, and the third stator terminal is joined directly to the other end of the secondary winding. The machine 15 is thus started as a split-phase induction motor. As shown, when the phase converter has run up to speed as an induction motor, it is brought into synchronism by the application of direct current to its rotor winding by closing switch 37, a switch 38 being operated to short-circuit the resistor 36 and to interconnect the three phase terminals of the machine 15 and 21. The machine 15 may be of the asynchronous type, however. |
