| 摘要 |
<p>PURPOSE:To prevent abrupt starting of an electric motor vehicle by eliminating the closure of a contactor for running the vehicle when a shorting circuit is formed in a thyristor chopper circuit. CONSTITUTION:When the main thyristor SM and a capacitor C1 of a thyristor chopper circuit CH are shorted or a chopper shorting contactor's contact MS is fused, the terminals A and B are shorted. When a key switch KS, and running switches FDS, RDS are closed to drive an electric motor vehicle, an electric current is flown in a closed loop or a DC power supply E-key switch S- running swtich FDS or RDS-diode D1 or D2-resistor R3-diode D7-diode D9-chopper circuit CH- connecting point B-DC power supply E. Since the potential of the connecting point A is, however, low, the terminal voltage of the capacitor C2 does not exceed the zener voltage VZ1 of the zener diode Z1. Accordingly, the thyristor SCR1 is not fired. Thus, the excitation coil MF or MR of the running contactor is not energized.</p> |
