Abstract: The active power factor correction (PFC) circuits are required for AC-DC converters to reduce the harmonics of the grid-side current. Traditional Boost PFC circuits cannot achieve a wide range of output voltage changes due to its inherent Boost characteristics. In this paper, a Buck/Boost bridgeless PFC converter is proposed to achieve a wider range of output voltage by alternating the boost path and buck path. In order to further reduce the grid-side current harmonics, this paper adopts a variable-carrier modulation method which adjusts the distribution ratio of the boost carrier and the buck carrier, so that the carrier varies with the output voltage and the total harmonic distortion is further reduced compared with the fixed carrier modulation method. Since the input side of the traditional single-phase PFC circuit produces double-frequency power, a large electrolytic capacitor is needed to be connected in parallel at the output side, this paper uses the bidirectional Buck-Boost circuit for power decoupling to achieve absorbing the double-frequency power. This paper introduces in detail the working principle and control strategy of the used buck/boost bridgeless PFC converter, and verifies the correctness and effectiveness of the buck/boost bridgeless PFC converter and its control method through experiments.