Modelling of losses due to eddy currents and hysteresis in converter transformer cores during failure

The paper deals with the analysis of eddy-currents and hysteresis losses in the core of three-phase transformer supplying a static converter bridge during failure of a diode in this bridge. The applied simulation methods are described as well as the results of an analysis in the most important case: the breakdown of one diode of the bridge produces an internal short circuit disconnected by the fuse. Then the operation continues without one diode, changing greatly the values of all currents and core losses. The computation of all quantities required the application of coupled circuit and field methods