Three Phase Current-Fed Semi Dual Active Bridge DC–DC Converter With Hybrid Operating Mode Control

Abstract

A high-frequency isolated unidirectional three phase (3p) current-fed (CF) semi-dual active bridge (SDAB) dc–dc converter is proposed for unidirectional power-flow applications suitable for wide input and load variations with small input current ripple, such as for fuel stacks and photovoltaic (PV) array. A hybrid operating mode control was proposed to handle the operating stability throughout full load range especially the light load conditions by which, dual-pulsewidth modulation (PWM) and phase shifted control with fixed clamping voltage was implemented over certain kind of load while varying clamping voltage using only dual-PWM (D-PWM) control was used under light-load conditions. The ideal power transferred expressions are derived based on the analysis of power transmission characteristics. The ideal rms expressions of the leakage inductor current are ideally derived for leakage inductance value optimization or minimizing the loss; and the ideal soft-switching conditions based on charges have been given. A 2-kW 3p-CF-SDAB prototype using SiC mosfet s has been built to verify the validity the proposed control strategy. With the proposed control, the steady-state performance throughout full load of range is pretty well. Seamless transition can be obtained between the two operating modes and the dynamic performance is good. The conversion efficiency is high and the loss distribution is given.