Energy Storage System Combining a 320-V, 12-F Electric Double Layer Capacitor Bank with a Bidirectional Isolated DC-DC Converter

This paper describes the design, construction, and testing of a 320-V, 12-F EDLC energy storage bank equipped with a bidirectional isolated dc-dc converter. A simple voltage-balancing circuit is proposed, which combines a center-tapped high-frequency transformer and the EDLC bank consisting of two 160-V, 24-F EDLC sub-banks connected in series. Experimental results including charging/discharging and self-starting waveforms are shown to verify the effectiveness of the proposed voltage-balancing circuit. The power loss in the voltage-balancing circuit is verified to be negligibly small during the charging/discharging operation.