A three-phase soft-switched high power density DC/DC converter for high power applications

The authors present three DC/DC converter topologies suitable for high-power-density high-power applications. All three circuits operate in a soft-switched manner, making possible a reduction in device switching losses and an increase in switching frequency. The three-phase dual-bridge converter proposed is seen to have the most favorable characteristics. This converter consists of two three-phase inverter stages operating in a high frequency six-step mode. In contrast to existing single-phase AC-link DC/DC converters, low RMS current ratings are obtained for both the input and output filter capacitors. This is in addition to smaller filter element values due to the higher-frequency content of the input and output waveforms. The use of a three-phase symmetrical transformer instead of single-phase transformers and a better utilization of the available apparent power of the transformer (as a consequence of the controlled output inverter) significantly increase the power density attainable.<>