Recently, the bi-directional dc-dc converter has been focused on because of the huge demand for diversification of power supply network including battery. The dual active bridge (DAB) dc-dc converter is one of the most popular circuits for bi-directional applications because of its simple structure. However, power efficiency at light load is the intrinsic problem of a bi-directional DAB DC-DC converter. In this paper, the simple solution with digital operation for the problem is proposed and experiments are performed with 1kW system. This method can reduce a switching surge without other circuits such as snubber and improve power efficiency at light load. Therefore it can reduce loss of switching surge and, improve power efficiency. From the results, 37% maximum power efficiency improvement at light load is confirmed. Furthermore, this method is capable of control in the conventional method in the heavy load range. Consequently, it is possible to reduce the switching surge and realize high power efficiency in a wide load range.

Abstract-Recently, the bi-directional dc-dc converter has been focused on because of the huge demand for diversification of power supply network including battery. The dual active bridge (DAB) dc-dc converter is one of the most popular circuits for bi-directional applications because of its simple structure. However, power efficiency at light load is the intrinsic problem of a bi-directional DAB DC-DC converter. In this paper, the simple solution with digital operation for the problem is proposed and experiments are performed with 1kW system. This method can reduce a switching surge without other circuits such as snubber and improve power efficiency at light load. Therefore it can reduce loss of switching surge and, improve power efficiency. From the results, 37% maximum power efficiency improvement at light load is confirmed. Furthermore, this method is capable of control in the conventional method in the heavy load range. Consequently, it is possible to reduce the switching surge and realize high power efficiency in a wide load range.

Recently, increased attention is being paid to power supply networks using energy storage devices such as batteries. Network topologies using bi-directional isolated DC-DC converters of low or medium capacity are required for the diversification of power supply networks. The dual active bridge (DAB) DC-DC converter is one of the most effective bi-directional isolated DC-DC converters. However, the circuit has some inherent problems such as degradation of power efficiency and the occurrence of surges during light-load operation. In this paper, we propose a control technique to solve these problems. From the experimental results, it is confirmed that the maximum power efficiency improvement was 16% for a light load. Applying two operation modes, the proposed operation in light load and the conventional operation in heavy load, the circuit can be operated across a full range of road. To switch between the two modes seamlessly, the precise boundary point of the two modes is needed for feedback control. Therefore, a precise static characteristic analysis with loss was carried out. From the results, the loss included simple equivalent circuit model was obtained. The root mean square error between the proposed analysis and the experimental results is within 4%.

Abstract-Recently, the power supply network with energy storage devices such as battery has been focused. This network topology uses bi-directional isolated DC-DC converter of low or medium capacity is required for the diversification of power supply network. The dual active bridge (DAB) DC-DC converter is one of the effective bi-directional isolated DC-DC converters. However, the circuit has some instinct problems such as degradation of power efficiency and the occurrence of the surge in light-load operation. In this paper, we have been done a static characteristic analysis and highly power-efficient technique for DAB DC-DC Converter at light load. Also the analysis results and the proposed technique are verified with some experimental results.

Recently, the bi-directional dc-dc converter has been focused on because of the huge demand for diversification of power supply network including battery. The dual active bridge (DAB) dc-dc converter is one of the most popular circuits for bi-directional applications because of its simple structure. However, power efficiency at light load is the intrinsic problem of a bi-directional DAB DC-DC converter. In this paper, the simple solution with digital operation for the problem is proposed and experiments are performed with 1kW system. This method can reduce a switching surge without other circuits such as snubber and improve power efficiency at light load. Therefore it can reduce loss of switching surge, and improve power efficiency. From the results, 37% maximum power efficiency improvement at light load is confirmed. Furthermore, this method is capable for control in the conventional method in the heavy load range. Consequently, it is possible to reduce the switching surge and realize high power efficiency in a wide load range.