Soft-Switching Technology of Bidirectional DC-DC Converter for High-Power Flywheel Energy Storage System

High-power flywheel energy storage system (FESS) is widely considered as a potentially major energy storage system in the future. In order to improve the practicality and reduce high-power loss brought by high-power FESS in charging and discharging operation modes, a quasi-resonant zero voltage switching (QRZVS) bidirectional DC-DC converter for high-power FESS is proposed in this chapter. Energy transfers in two directions with switches works alternately, and the QRZVS circuit with only \( {L_\mathrm{{r}}}-{C_\mathrm{{r}}} \) passive components suppresses the turn-on and turn-off loss during wide range of duty-cycle of IGBT. This DC-DC converter with two-quadrant operation has the characteristics of simple structure and low switching loss, realizing the ability of quick charge and discharge and reducing the electromagnetic interference level of the system. Testing results verified the advantages of the converter.