A dual-dc-port ac–dc converter-based structure is proposed to suppress the second-order ripple power in a single-phase ac–dc power system. By constructing a direct power conversion path from the input to the decoupling capacitor, the number of power conversion stages of the second-order ripple power can be effectively reduced, which is beneficial to improve the efficiency of the system. New families of dual-dc-port ac–dc converter-based second-order ripple power suppression circuits are proposed to implement the power decoupling scheme. One of the circuits is taken as an example to verify the effectiveness of the decoupling structure. The operation modes, power conversion characteristics, and control strategies of the converter are analyzed in detail. A 1-kW prototype is built and tested to verify the feasibility and advantages of the proposed solution.