Bidirectional Universal Converter Transformer Design for Electric Vehicle Onboard Charging

This paper highlights the design aspects of the universal converter transformer as part of an effort done to use the universal converter for onboard charging applications for electric vehicles. Today's requirements of onboard charging ask for bidirectional follow capabilities and an ability to interface with various power grid types (single-phase, three-phase three- wires, and three-phase four-wire, etc.). Such requirements increase the difficulty of designing the transformer due to the high input to output voltage gain range of the DC-DC converter. The universal converter uses a dual active bridge that maintains consistent performance across all the operating regions. This paper provides the necessary steps of building the transformer and shows the experimental results to assess the proposed design method.