| 摘要 |
<p>A device for overvoltage protection of a rectifier bridge feeding a d.c. motor and implemented using fully gate-controlled solid-state switches without zero diodes, and for control of the d.c. motor during emergency braking is disclosed. To protect at least the switches of the rectifier bridge against overvoltages and to control the d.c. motor during emergency braking, the device incorporates a capacitor connected via diodes both to the d.c. circuit and the a.c. circuit and, connected in parallel with said capacitor, a series cirucit of a fully gate-controlled solid-state switch and a resistor, said solid-state switch being controlled by a control unit in such manner that, when the voltage between at least two connections in the a.c. or d.c. circuit rises above the voltage across the capacitor, the solid-state switch turns on when said voltage between the connection rises above the excitation value and turns off when it falls below the turn-off value, and that during emergency braking the solid-state switch is turned on.</p> |
