Design and Comparison of Two Front-end Dc/Dc Converters: LLC Resonant Converter and Soft-switched Phase-shifted Full-bridge Converter with Primary-side Energy Storage Inductor

This paper presents detailed design and comparison of two front-end Dc/Dc converters which are suitable especially for the medium-power level applications with low output voltage and high output current both. Where, the LLC resonant converter drawn more and more attention recently shows its essential advantages in high conversion efficiency and high power density. However, due to the variable-frequency control strategy, its slow response especially in burst-mode with light-load or null-load makes the design more difficult. On the oppose side, the soft-switched Phase-Shift (PS) Full-bridge (FB) converter with primary-side energy storage inductor proposed in the foregoing work can be operated in CCM, BCM and DCM respectively according to the different designs. Where, the optimum design consideration indicates that the BCM and DCM operation modes can help to obtain high conversion efficiency. Additionally, thanks to the conventional phase-shift control strategy, it can obtain fast response during the burst-mode with light/null load. Finally, two lab-made prototypes of these two Dc/Dc converters (300 Watts, 100 kHz) are built up to verify the theoretical analysis and comparison.