Dual active bridge DC-DC converter using both full and half bridge topologies to achieve high efficiency for wide load

This papar proposes which the Dual Active Bridge (DAB) converter changes between Full Bridge (FB) converter´s operation and Half Bridge (HB) converter´s operation on the secondary side of the high frequency transformer depending on the output power. With the HB converter operation´s, the iron loss of the transformer becomes small because the secondary voltage of the transformer becomes half compared to the FB converter´s operation. In addition, Zero Voltage Switching (ZVS) is achieved at the light load. Therefore, the proposed circuit can obtain the high efficiency for the wide load by the changing the HB and the FB converter´s operation depending on the output power. In this paper, the changing point between the HB and the FB converter is derived using the loss calculation. The validity of the proposed circuit is verified by 800-W prototype. From the experimental results, it is confirmed that the proposed circuit has the two local maximum efficiencies which are 92.9% and 93.4% at the light load and the heavy load using the proposed circuit.