New bi-directional DC/DC converter for supercapacitor interfacing in high-power applications

This paper presents a new bi-directional DC/DC converter for supercapacitor interfacing in high-power applications. The converter acts as a VSI-based step-down DC/DC converter during the supercapacitor charging mode and as a qZSI-based step-up DC/DC converter during the energy recovery mode. To provide voltage matching and galvanic isolation the medium frequency transformer was implemented. To ensure higher voltage boost of the SC voltage during the discharge the qZSI with a two-stage quasi-Z-source (qZS) network was introduced. The paper analyzes and discusses the operation of the new converter mostly concentrating on the energy recovery (boost) mode. The operation of the two-stage qZS-network is analyzed in detail. Guidelines are presented for the new converter design. Finally, theoretical background was verified by the simulations.