Phase-Shift Fixed-Frequency LCLC Resonant Converter: Analysis of Operational Modes and Mitigation of Parallel Capacitance of Output Diodes

LCLC resonant topology is fascinating in highvoltage applications due to its capability of absorbing all parasitic parameters of step-up transformers and its soft-switching property. Another important advantage of this topology is that the diodes of the output rectifier are softly turned-OFF, so there is low reverse recovery loss in these diodes. Because of mentioned fact, the output rectifier can be made of some series low-voltage diodes instead of one high-voltage and expensive diode. This fact allows for producing low-cost highvoltage converters with minimum switching and rectifying losses. This paper introduces the operational modes of the phase-shift fixed-frequency LCLC resonant converter and analyzes them to investigate the intrinsic characteristics of this topology. Then, using simulations the critical circumstances of the diodes of the output rectifier is illustrated. Theoretical analysis and simulation results are compared with the experimental results using a prototype converter.