Impact of Resonant Tank Structures on Transformer Size for a High Power Density Isolated Resonant Converter

Resonant converters are popular for high power density applications because of their advantages over pulse-width modulation (PWM) converters. For a given resonant converter, the resonant tank has different structures when the transformer position is changed in the resonant tank. Without any changes in resonant tank design or influencing system performance, the difference in transformer positions significantly affects the voltage and current stress on the transformer, and thus the transformer volume. The voltage and current stresses on the transformer as well as the influence on the resonant components are summarized, and three possible basic resonant converters are compared for use; the series resonant converter (SRC), the parallel resonant converter (PRC) and the series parallel resonant converter (SPRC). Suitable structures for high power density applications are discussed, and a PRC with two different resonant structures is implemented for experimental verification.