Harmonic analysis of a high speed train with interlaced four quadrant converters

The paper deals with the power quality analysis of interlaced four quadrant (4Q) converters. These are in fact the input stages of the locomotives and high speed trains supplied by 25 kV, 50 Hz and 15 kV, 16,7 Hz lines. Due to the high power needed for the trains circulation, the 4Q converter generates a high amount of harmonic currents, dangerous most of all for the signaling systems and communication devices. The presence of more converters gives the opportunity, using dedicated control logics, to interlace them in order to reduce the harmonic content in the absorbed current. In the paper a suitable model of more 4Q converters is developed. The control logic implemented in the model allows the evaluation of the harmonic contribution of both single converter and the interlaced configuration. Some simulation results will be presented.