Diode-Clamped Three-Level Interleaved LLC Resonant Converter for Reducing Input Current Ripple and Switch Voltage Stress

This paper proposes a novel diode-clamped three-level interleaved double LLC resonant converter for reducing input current ripple and switch voltage stress in high-voltage DC applications. The proposed converter utilizes a three-level structure with a diode-capacitor clamping circuit, restricting the voltage stress on each main switch to exactly half of the input voltage, which enables the use of low-voltage-rated power switches. Additionally, 180-degree phase-shifted interleaved control is applied to the double LLC resonant tanks, theoretically canceling the input current ripple to zero without adding a large input filter. Furthermore, by implementing dual-function capacitors, vulnerable electrolytic capacitors are completely eliminated and replaced by long-lifespan film capacitors, significantly enhancing power density and system reliability. Experimental and simulation results are presented to comprehensively verify the performance and feasibility of the proposed converter.