Protection wiring on the LC input filter of a power circuit for networks having voltage which returns suddenly

摘要

The invention relates to protection wiring on the LC input filter of a power circuit for networks having voltage which returns suddenly, having a controllable freewheeling circuit which is connected in parallel with the inductor and, when the network voltage returns and the capacitor is discharged or partially discharged, limits the rise in the voltage on the capacitor to a value which is increased above the rated voltage by a permissible voltage fluctuation, virtually short-circuits the inductor and converts its energy content into heat, especially for supplying railway converters. In order to create protection wiring which even withstands multiple, periodically occurring power interruptions without any reaction, and furthermore manages with a simple and small construction with cheap components and increases the operational readiness of the converter, it is proposed according to the invention that the series circuit of a thyristor (5) and of an uncontrolled valve (6) be used as the freewheeling circuit and that the thyristor (5) be driven as a function of the voltage reversal on the inductor (1) during self-induction, after completion of the charging process on the capacitor (2). <IMAGE>