Analysis of a low loss turn-off network for a GTO chopper for international railway cars operating under different railway supply voltages

A simulation considering the reverse current of the semiconductor devices is presented, for a turn-off network of a GTO (gate turn-off thyristor) chopper used in a railway car supplies. Matrix calculus is used for the calculations. The simulation allows, together with the measurements, an analysis of the parasitic effects in the snubber network and a relatively exact loss estimation. These effects are important for the exact dimensioning of the protective circuit, i.e., of the turn-off network. Selected simulation results of characteristic system quantities of the chopper are compared to measurement results, and good agreement between simulation and measurements is observed