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 twolevel 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.

A Bidirectional LLCL Resonant DC-DC Converter With Reduced Resonant Tank Currents and Reduced Voltage Stress of the Resonant Capacitor

“…2(a) will be analyzed as a comparative topology in this section. Meanwhile, according to (7) and (8), it can be observed that the voltage gain of LLCL is directly affected by the transformer turns-ratio, quality factor, and the resonant inductance ratios, which is similar to the other LLC-type resonant converters. Hence, these variables that reflect the converters' working conditions will be considered in the comparisons.…”

“…By means of (2), (6), Fig. 9, and Kirchhoff's current/voltage laws, the dc voltage gain of LLCL in forward mode (MF) and backward mode (MB) can be deduced as (7) and 8…”

“…According to (7) and 8, when LLCL operates at the main resonant frequency fr1 (i.e., fn=1), it can be found that the ratio between UH and UL is constant at (1+k)n regardless of the direction and amplitude of the transferred power. Hence, to make the voltage gain of LLCL exactly match the rated values of UH and UL when fS=fr1, set:…”

“…Energy utilization rate is therefore improved by the implementation of peakclipping and valley-filling. Thus, the research on BDCs will become one of the most promising directions for developing ESSs [5]- [7].…”

Design and analysis of three‐level hybrid boost converter based on T‐type inverter for solar photovoltaic system

“…The converter was operated under zero voltage switching but it is limited to a unidirectional operation only. For bidirectional operations, another half‐bridge T‐type DC‐DC converter is added to the secondary side of the high‐frequency transformer as proposed in [27]. Further development has seen a full‐bridge T‐type DC‐DC converter topology that was proposed to improve the power handling capability with a wider input voltage range but at the expense of more power switches [28, 29].…”