Development of ultra lightweight static inverter for electrical multiple unit

One of the major trends in power electronics is increasing the switching frequencies. The advances in the frequency elevation have made it possible to reduce the total size and weight of the passive components such as capacitors, inductors and transformers in the static inverter and hence to increase the power density. The system consists of hard switched boost chopper, soft switched high frequency inverter, high frequency transformer and rectifier. This system features a boost chopper to control the input current and to set up a controlled DC link. And a soft switched half bridge inverter powers a high frequency transformer from this DC link. Therefore the 150DC link voltages are inverted into 8kHz high frequency ac voltage, which is isolated by high frequency transformer, and then the output voltage of the transformer is rectified by single phase rectifiers. The dynamic performance is also improved. This document describes several aspects relating to the design of resonant DC/DC converter operating at high frequency(8KHz) and the converter topologies and the control method, which result in soft switching, are discussed.