| 摘要 |
1,219,393. Control of D.C. motors. WESTINGHOUSE ELECTRIC CORP. 7 March, 1969, No. 12208/69. Heading H2J. [Also in Division G3] In a system for limiting the rate of change of acceleration of a vehicle, a control signal is developed across a resistor 34 in the collector circuit of a transistor 35 with emitter current supplied from a constant D.C. source through an adjustable resistor 36. The collector circuit includes a capacitor 37 associated with rectifier 38, the voltage across the capacitor providing a modified signal which follows the control signal on line 33 but which is limited to a desired rate of change. The control signal is further modified by a load weight circuit 42 and is then applied to circuit 32 to be compared with the actual motor current which is represented by a signal derived through transductor 43. A chopper 14, which comprises main thyristor 15 with a commutating capacitor 16 and turn-off thyristor 17, is turned on and off to maintain the desired average current fed to traction motors M1-M4. The chopper is started by firing the thyristor 17 to charge capacitor 16, after which the thyristors 15, 18 are fired to energize the motors and to complete an oscillatory circuit through reactor 19 and thyristor 18 to capacitor 16. The chopper is turned off by firing thyristor 17 which applies the reverse voltage of capacitor 16 across thyristor 15. For dynamic braking, the motors are connected in two loop circuits having resistors 26, 27 in common, with the chopper 14 connected across the resistor 26. In another arrangement, the circuit for limiting the rate of change of acceleration comprises two transistors with their bases interconnected, resistors for independently adjusting the emitter currents, and a common collector circuit including the control signal source, the capacitor being connected in series across the collectors, Fig. 1 (not shown). In this circuit, different maximum rates of change are obtained for increase and decrease in the control signal. |
