GaN transistor based Bi-directional DC-DC converter for stationary energy storage device for 400V DC microgrid

This paper presents a novel GaN transistor based bidirectional isolated DC-DC converter for stationary energy storage device (SESD) for 400V DC microgrid. The improvements achieved in the application includes: first, benefitting from the internal ultra-fast free-wheeling diode, the converter´s operation range can be expended to light load conditions (switches operate in hard switching). The light load efficiency can be greatly increased. Second, because of its low switching loss and on state resistance, the heavy load efficiency is increased. Third, the snubber inductor which is indispensable in Si device based converter can now be omitted in the GaN version. The power stage design as well as a loss analysis of GaN is based on a steady state analysis and PSpice simulation. Experimental results are presented for a 500 W bidirectional dc-dc converter prototype.