Frequency converter

摘要

A frequency converter has a rectifier (V1 ... V6) as a supply circuit from the supply network (1, 2, 3), a DC voltage intermediate circuit (L1, C1) and an invertor (V11 ... V16, V21 ... V26) in a circuit which is free of reverse voltage and where the invertor valves are individually turned off. Each branch of the invertor consists of two reverse-conducting main thyristors (V11 ... V16) in series with in each case one inductor (choke) (L11 ... L16) which limits the rate of current rise (di/dt). A turn-off circuit is arranged in parallel with each main thyristor (V11 ... V16). This turn-off circuit consists of the series circuit of a reverse-conducting turn-off thyristor (V21, V26) with a turn-off capacitor (C21, C26) and a ring-around inductor (L21, L26). A three-feed system having a variable voltage and variable frequency is available at three output terminals (R, S, T) (R, Y, B in systems other than in Germany). <IMAGE>