A Novel Symmetrical Phase Dual CLLC Resonant DC-DC Converter for the Hybrid AC-DC Microgrid

This paper proposes a symmetrical dual phase CLLC resonant DC-DC converter with hybrid pulse frequency modulation and phase-shift control scheme for the hybrid DC-AC microgrid. The presented converter consists of two six-switch full bridges and dual phase CLLC (DPCLLC) resonant tanks. This dual phase converter can achieve softswitching on the both sides. The topology, average model, operating principle and power transmission characteristics are analyzed in detail. The control scheme of the proposed dual phase converter is to regulate the switching frequency of MOSFETs gate signal and the duty cycle of the resonant tank input voltage. In order to reduce the overshoot of the DPCLLC converter, a soft-start strategy is adopted, which increases the switching frequency and reduces duty cycle during the start-up state. The simulation results in PLECS can verify the feasibility of the dual phase CLLC converter and the control method.