Synchronous rectified Soft-Switched Phase-Shift Full-Bridge converter with primary energy storage inductor

This paper presents a synchronous rectified Soft-switched Phase-Shift (PS) Full-bridge (FB) converter with primary-side energy storage inductor, which can be utilized in low output voltage and high output current applications. This converter can be operated in CCM, BCM and DCM respectively based on different designs. However, optimum design consideration indicates that the BCM and DCM operation modes are much more suitable for this converter. Primary-side energy storage inductor can help leading leg switches achieve ZVS condition easily. DCM and BCM operation modes can make primary-side lagging leg switches and secondary-side synchronous rectifiers (SR) achieve ZCS condition. Slow di/dt of triangular current at secondary-side also lead to little reverse recovery loss of SRs' body diodes. The voltage stress across SRs can be clamped by output voltage and the low break-down voltage SRs are utilized to reduce conduction loss. Finally, a high efficiency 300 Watts 100 kHz prototype is built up to verify the theoretical analysis and design.