Performance of IGBTs Series Connection Technologies for Auxiliary Power Supply System

This paper presents a novel auxiliary power supply (APS) system for the commuter trains with 1.5kVdc employing series-connected 1.2-kV general purpose IGBTs as a switching device, substituted for high-voltage IGBTs over 3kV. The carrier frequency of 5kHz in the APS is realized due to considerable low switching loss of the IGBTs. Voltage balance across the series connected IGBTs are achieved by magnetically coupling all the gate lines using a simple two-winding transformer without snubber circuits. To ensure that such the high carrier frequency is effective on APS performance, sound level from filter and output voltage stability with a sudden changed load are evaluated using a single-phase inverter, and then compared with that of a conventional carrier frequency. On the basis of the series connection technique with the 1.2kV IGBTs, a prototype of the APS system is designed and built for the actual uses, and then its performance is evaluated at its rating specifications. From the results, it is confirmed that the APS system features smaller volume and lower sound level rather than conventional ones with the high-voltage IGBTs.