Abstract: Aiming at a series of problems caused by the cascaded H-bridge double-line frequency voltage ripple and power mismatch at the present stage,a modular three-phase photovoltaic inverter topology based on a four-port LLC is proposed to solve the inter-phase power mismatch problem fundamentally. Meanwhile,this topology is able to suppress the double-line frequency voltage ripple in the output power of the system. The essential reasons for the formation of the in-phase power mismatch problem is summarized and analyzed and an adaptive boosting distributed control strategy is proposed to improve the ability of the system to cope with the in-phase power mismatch and expand the stable operation range of the cascade system in the paper. The distributed control architecture reduces the information interaction between individual modules and reduces the complexity of the control system. Simulations and experiments verify the effectiveness of the proposed topology and control strategy.