Balanced Power Device Currents Based Modulation Strategy for Full-Bridge Three-Level DC/DC Converter

This paper proposes a new modulation strategy with balanced power device currents for the full-bridge three-level (FBTL) DC/DC converter. The proposed modulation strategy has two working patterns, which can not only realize zero-voltage switching (ZVS) but also satisfy the wide input voltage range. More significantly, the two working patterns of the proposed strategy can both balance the currents among the power switches and clamping diodes in comparison with the conventional control strategies causing current imbalances among the power switches and clamping diodes. Consequently, the proposed strategy can balance the thermal stresses among the power switches and clamping diodes, which would thus improve the converter’s reliability. Finally, the experimental results, obtained by a built 1.5 kW experimental prototype, verify almost zero current difference and zero thermal stress difference among the inner power switches, outer power switches, and clamping diodes under the proposed strategy.