Power conversion apparatus for DC/DC conversion using dual active bridges

DETAILED DESCRIPTION The power conversion apparatus of the present invention provides soft-switching DC/DC conversion suitable for high power applications.
The soft switching makes possible a reduction in device switching losses and an increase in switching frequency.
The conversion apparatus of the invention can be implemented in a single phase system having dual active bridges with the power transferred between them through a single phase transformer.
A three-phase dual bridge converter in accordance with the invention 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 the output filter capacitors.
This advantage is in addition to the smaller filter element values which can be utilized due to the higher frequency content of the input and output waveforms.
The three phase system has the further advantage that a three phase symmetrical transformer allows better utilization of the available apparent power of the transformer (as a consequence of the controlled output inverter), significantly increasing the power density obtainable.
Further objects, features, and advantages of the invention will be apparent from the following detailed description when taken in conjunction with the accompanying drawings.