Analysis and Design Trade-Offs of a Multi-Winding High-Frequency Transformer for a Battery Charger

This paper addresses the design of a multi-winding high-frequency transformer for a multiport unified battery charging converter. The transformer design specifications are derived from the steady-state analysis of the converter and the cross-regulation challenges that exist in multiport converters. A loss model is developed, and a design procedure is outlined for the multi-winding transformer. The high-frequency transformer is designed and implemented, and core losses under various excitation conditions are measured using a core loss tester circuit. A 1.2 kW hardware prototype of the multiport converter is developed in the laboratory. Hardware results at rated operating conditions and core and winding temperature data are provided to validate the operation of the transformer and the multiport converter.