Circuit arrangement and control method for a power inverter having impressed intermediate-circuit voltage

摘要

There are known power inverters which have two branch pairs connected in series between the poles (P, N) of an intermediate circuit, the branch pairs each consisting of a triggerable and resettable semiconductor switch (G1, G2) and an antiparallel-arranged reverse-power diode (D1, D2). In order to reduce the harmonic currents, it is proposed to connect the common connection point of the two branch pairs, which point forms the AC voltage terminal (A), via a branch pair consisting of two antiparallel-arranged thyristors (T1, T2), to the mid-point (M) of the intermediate circuit, which produces a 3-point arrangement. For using the power inverter in a three-phase rail vehicle, the mains-protection thyristors of a four-quadrant controller are connected to the mid-point of the intermediate circuit. The releasing of the thyristors is carried out, observing their hold-off intervals, by triggering and resetting the triggerable and resettable semiconductor switches. <IMAGE>