An LLC DCX Converter Parameter Design Method Considering Junction Capacitances and Current Phase Angle of Dead-Time High-Frequency Resonance

Abstract

This article proposes a resonant parameter design method for a high-frequency power LLC DCX converter, aiming to achieve zero-voltage switching (ZVS) under high-power conditions and improve the overall performance of the converter. First, a detailed derivation process of the electrical parameters’ design is presented, and an LLC converter dead-time state model is established. The analytical formulation encompassing dead time and resonant parameters combines the influence of junction capacitances and high-frequency resonance during dead time. Through manipulation of the phase angle of the high-frequency resonant current within the dead time, a comprehensive assessment of the ZVS is conducted. This assessment takes into account variations in power level and phase angles. This analysis realizes the matched phase angles and electrical parameters to achieve ZVS. Moreover, this study focuses on resonant capacitors incorporating withstand voltage and voltage gain, and resonant inductors addressing matched parameters and stability. Thus, the method proposed improves accuracy and safety, assisting the design of parameters. Finally, a 30-kHz $2\times 50$ -kW prototype is constructed and validated through experiments to confirm the suggested methodology, where the efficiency of the prototype at full load is 99.06%.