Bidirectional Isolated Dual Full-bridge dc-dc Converter with Active Clamp for EDLC

A high-power bidirectional isolated dual full-bridge dc-dc converter with an active clamp for a electric double layer capacitor (EDLC), which is installed into a dc distribution system, is investigated. This dc-dc converter consists of two full-bridge converters on both low and high voltage sides, a high-frequency transformer, an active clamp switch and a capacitor. Phase-shift control is employed to regulate charge and discharge power, and soft-switching technique is also applied to reduce switching losses. In addition, a new control scheme to suppress current flowing into the active clamp is introduced. A 1-kW proto-type dc-dc converter using an EDLC is made and experiments are carried out to verify the proposed control scheme. Soft-switching operations of switches are achieved under both of the charge and discharge modes. Efficiency of the 1-kW converter is measured and detailed loss analysis is conducted. Moreover, a 1-MW dc-dc converter is designed and its efficiency is estimated.