Triple-Phase-Shift Modulation Strategy for Diode-Clamped Full-Bridge Three-Level Isolated DC/DC Converter

Abstract

A triple-phase-shift (TPS) modulation strategy with reduced transformer's voltage stress is proposed in this paper for the diode-clamped full-bridge (FB) three-level isolated DC/DC converter. The proposed strategy can keep the transformer's maximum voltage changes ( $\Delta \text{V}$ ) at only half of the input voltage ( $V_{in}$ /2) by employing three phase-shift delays. Consequently, comparing with the conventional strategies, the merits of the proposed strategy include: 1) reducing the voltage change rate (dv/dt) on the transformer and 2) improving the transformer's voltage harmonics due to the merit of the multi-level voltage. Additionally, the proposed strategy has two operating modes with zero-voltage switching (ZVS) for fulfilling the wide input voltage range. Finally, the proposed strategy is verified by both simulation and experimental results.