A Three-Port Three-Phase DC-DC Converter for Hybrid Low Voltage Fuel Cell and Ultracapacitor

A novel three-port three-phase DC-DC converter is proposed in this paper to interface with low voltage fuel cell and ultracapacitor (UC). Major features of the converter include: 1) provide an integrated energy conversion solution with combined power flow from fuel cell and UC; 2) draws and injects smooth current from the fuel cell and UC; 3) increase input current rating by interleaving three phases, not by paralleling components; 4) reduce core number and current ripple with improved efficiency by integrating three input inductors into a single core with coupling; 5) achieve zero-voltage-switching (ZVS) over a wide range by hybrid pulse-width-modulation (PWM) and phase-shift-modulation (PSM) control. This converter has a great potential application in fuel cell vehicle and distributed power generation. The operation principle, steady state analysis and integrated magnetic design are presented in the paper. Circuit simulation results are provided to verify the theoretical analysis