| 摘要 |
The voltage supply between live rail and earth is connected across two capacitors (14a)(14b) with a centre-tap connected to the mid-point of two DC chopper circuits. The choppers comprise semiconductor switches (21a)(21b) and series diodes connected across the supply terminals. The output of each chopper control is connected with its associated DC motor (M). The return terminal of each series motor is connected via a diode (45a-b) to the negative or positive supply rail. A control switch (44) is in parallel with the motors. - By closing or opening the control switch the motors are connected together in series or in parallel and, due to the proportional control of the current to each motor by the chopper circuits, a two-stage - 0 to 50%, 50 to 100% - control of the supply to the motors is possible. |
