1kW, 400V/12V high step-down DC/DC converter: Comparison between phase-shifted full-bridge and LLC resonant converters

Phase-shifted full bridge (PSFB) and LLC resonant converters with center-tapped rectifier are two popular solutions for auxiliary power module (APM) in the electrical system of electric vehicles (EVs). The high output current and the requirement for a wide gain range due to the high-voltage battery variable voltage bring unique challenges in the design of APMs. This paper provides a comprehensive analysis of the operational principle of these two topologies. Two 1kW prototypes are designed and developed to provide a realistic comparison. The manuscript provides basic guidelines about the topology selection between these two converters for high step-down ratio and high output current applications.