High Efficiency Voltage Balancing Dual Active Bridge Converter for the Bipolar DC Distribution System

In this paper, a novel voltage balancing dual active bridge (VB-DAB) converter, which integrates the DAB converter with voltage balancer (VB), is proposed for the bipolar DC distribution system. The proposed converter is configured to connect two loads to the transformer secondary center-tab of the DAB converter, and any additional components are not added. The proposed converter operates on the same principle as the DAB converter, and it keeps the two output voltages on the secondary side the same. Besides, an imbalance current offset between the two loads is bypassed only on the secondary side of the transformer. Hence, it does not adversely affect the converter except for the secondary RMS current since this offset current. Consequently, the proposed VB-DAB converter integrates VB without any additional components, and there is no additional loss in the corresponding components. Thus, it is suitable to achieve high efficiency and high power density. The feasibility of the proposed converter has been verified with 3 kW prototypes under 380 V input and 190 / 190 V output conditions.