Triple-Phase-Shift Control Strategy for Full-Bridge Three-Level (FBTL) DC/DC Converter

This paper proposes a triple-phase-shift (TPS) control strategy for the full-bridge three-level (FBTL) DC/DC converter to reduce the voltage stress and harmonics on the transformer. The proposed control strategy is composed of three phase-shift delays to keep the maximum voltage changes $(\mathbf{\Delta} \mathbf{V})$ on the transformer's primary side at only half of the input voltage $(\boldsymbol{V}_{in}/2)$, which is different from the conventional control strategies causing the higher voltage changes with value of ${V}_{{i}\boldsymbol{n}}$. Therefore, the proposed control strategy can effectively reduce the voltage change rate $(\boldsymbol{d}\boldsymbol{v}/\boldsymbol{d}\boldsymbol{t})$ and voltage harmonics on the transformer due to the benefits of multi-level voltage produced by the three phase-shift delays. Additionally, the proposed TPS control strategy has two working modes, which can thus have wide voltage gain. Finally, the experimental results are presented to verify the proposed control strategy.