Design and optimization of a high performance isolated three phase AC/DC converter

This paper presents the design and optimization of a high performance isolated three-phase AC/DC converter that converts variable frequency 115 V AC voltage into isolated 28 V DC voltage. The main design target is to maximize converter rated power within given loss, size limitations and operation requirements. A two-stage structure, consisting of an active front-end (AFE) converter and an isolated DC/DC converter, is employed. To complete the design and optimization of the multi-converter system, a hierarchical design and optimization approach has been developed to explore the system loss-size Pareto front with considerations of thermal management, EMI performance and power quality. Methods for component optimization and loss calculation are introduced. Based on the design results (system loss-size Pareto front), a Vienna rectifier and an LLC resonant converter were selected for AFE and DC/DC stage respectively. Finally, a 1.2 kW convection cooled prototype was built and experimentally tested. It achieved 97.1% full load efficiency and 22 W/inch
³
power density. Compliance with EMI and power quality standard was experimentally verified.