Three-phase capacitor circuit for damping commutation overvoltages of a self-commutated invertor having a constant intermediate-circuit current

摘要

Three-phase capacitor circuit for damping commutation overvoltages of a self-commutated invertor having a constant intermediate-circuit current for supplying three-phase networks or three-phase machines which are intended to be supplied in frequency-decoupled manner via a self-commutated link converter having GTO thyristors. For this purpose, the current is fed back by capacitors (C1, C2, C3) connected via output leads, through current transformers (T1, T2, T3) and a six-pulse diode rectifier. A resistor (R4) is used for discharging the capacitor (C4) into the DC intermediate-circuit (2), through which the discharge current of the capacitor (C4) flows back into the three-phase mains or into the three-phase machine via an intermediate-circuit inductor (L11) and the GTO thyristors (V11 to V16) of the invertor. <IMAGE>