| 摘要 |
1,048,997. Control of D.C. motors. SEVCON ENGINEERING CO. Sept. 23, 1964 [Oct. 5, 1963], No. 39300/63. Heading H2J. Relates to a control system for a batteryoperated motor as described in Specification 950,734 comprising a controlled rectifier pulse generator including capacitor C, and means for adjusting the pulse frequency and thereby the power applied to the motor, the current flow being maintained during the interpulse periods. A controlled rectifier SCR 3 is provided for stopping the inductive effect of the battery reducing the stored charge in the capacitor and thereby preventing turn-off of the controlled rectifier in the pulse generator. When the main current-carrying rectifier SCR 2 is switched off, capacitor C charges through rectifier SCB 1 to the peak voltage of the battery. When the battery returns to its normal open-circuit voltage, the capacitor is unable to discharge through diode D 1 since rectifier SCR 3 is blocked, the capacitor retaining the increased charge. Firing of rectifier SCR 2 discharges the capacitor C through rectifier SCR 2 , inductor L, and rectifier SCR 3 , the latter being fired by transistor TR 1 at the same instant as the rectifier SCR 2 is fired. Contactor SC short-circuits the pulse generator and connects the motor directly to the battery. Resistor R 5 and diode D 4 are connectible between the battery and the gate of the rectifier SCR 3 to ensure that the rectifier is in a condition for firing when the contactor opens. A connection including diode D 6 is provided between the anode of rectifier SCR 3 and the firing electrode of rectifier SCR 2 to ensure that the latter is not fired prematurely after opening of the contactor SC. |
