A 98.8% efficient bidirectional full-bridge isolated dc-dc GaN converter

The paper presents the design and development of an ultra-high efficiency bidirectional isolated full bridge dc-dc converter using Gallium Nitride (GaN) devices. To achieve ultrahigh efficiency, GaN devices, synchronous rectification and high efficiency magnetics are used. The proposed bidirectional converter allows a power flow in both directions using the same power components; this increases power density and reduce the cost. The performance of a 1.7 kW bidirectional converter is experimentally validated in both forward direction (buck mode) and backward direction (boost mode). The converter operates at a switching frequency of 50 kHz with a voltage of 130V at one side and 52V at the other side of the converter. The fast switching speed of the GaN devices are utilized to achieve extremely high conversion efficiency thus reducing the total volume of the converter. The high power GaN converter has attained an extremely high efficiency of 98.8% in both the directions. This paper demonstrates the highest achievable conversion efficiency with the present technology.