Research Of The Bi-directional DC-DC Converters Based On Current-Fed Half-Bridge Topology

A 28V/270V soft-switching bi-directional DC-DC converter for the aircraft 270V high voltage direct current electric power generating system is researched in this paper. The summarizing on the research work about the bi-directional DC-DC converter at home and aboard shows that, the specification of the bi-directional DC-DC converter for the aircraft 270V high voltage direct current is not satisfied in these published techniques. Looking for the new topology, soft switching technique and control strategy is necessary.The bi-directional DC-DC converter based on current-fed half bridge was studied firstly. The inductor is appropriately designed to satisfy the ZVS for all power devices. A control scheme adopting one port voltage regulated and another port current regulated is proposed to realize the energy transfer freely in bi-directional.By introducing an active resonant branch to the secondary of the transformer, the zero-current-switching (ZCS) and pulse-width modulation (PWM) are obtained. By adopting asymmetrical control strategy, the ZCS and PWM are also achieved. The using of insulated gate bipolar transistor with reverse blocking (RH-IGBT) is a new attempt. By using RH-IGBT the voltage spike and the spike of resonant current are eliminated.By introducing an active clamping branch to the primary of the transformer, the zero-voltage-switching (ZVS) of all power switches is achieved and the voltage spike on them is clamped. The path for the inductor current when the duty cycle is less than 0.5 is also provided.Finally, a novel bi-directional DC-DC converter is proposed. The main circuit topology is combined by a current-fed half bridge and a voltage-fed half bridge. A novel phase-shift plus PWM strategy is adopted to realize ZVS for the switches and reduce the circulating conduction losses. Decoupling the phase-shift angleφand the duty cycle d control, a simply control circuit is proposed. A prototype converter rated at 1.5kW, 28V/270V and 100kHz is studied, the efficiency of the converter exceed 89.5% at full load and the highest efficiency is 96.9%. The dynamic and steady state performance of the new converter are satisfied.