Novel three-level T-type isolated bidirectional DC-DC converter

Abstract

This study presents a novel three-level T-type isolated bidirectional DC-DC converter (3LTT-IBDC) for bidirectional DC power transfer. Owing to of the T-type structure of the proposed converter it has less number of switches and thus, lower cost and higher efficiency, as well as easy control are the advantages of the proposed converter compared to three-level counterparts. Additionally, 3LTT-IBDC is more reliable than three-level converters since unequal voltage blocking does not occur in T-type structure. Moreover, the symmetrical operation of the isolation transformer due to three-level symmetrical voltage waveform, lower voltage stress of switches and thus, higher efficiency are other advantages of 3LTT-IBDC compared to two-level counterparts. Here, the DC voltage gain and power transfer characteristic of the proposed converter for steady-state operation and the expressions of the leakage inductance are derived. The proposed converter is simulated using PSIM. A 2-kW prototype is built to verify the theoretical analysis of the converter. Theoretical and experimental results show a good agreement and validate the competency of the presented converter design. The efficiency of the proposed converter and switching transitions of the switches are analysed. The full load and maximum efficiency of the converter are measured as 96.27% and 96.81%, respectively.