A Soft-Switched CCM Bridgeless PFC Rectifier for 240-W USB-PD EPR Wall Adapter

State-of-the-art bridgeless power factor correction (PFC) rectifiers commonly face challenges, such as hard-switching losses in continuous conduction mode (CCM) and high conduction and magnetic losses in critical conduction mode (CRM) or other soft-switched modes. These limitations restrict the efficiency and power density of these rectifiers in use for USB-PD applications. This article presents a novel two-stage converter that achieves soft-switching for a CCM front-end bridgeless PFC rectifier while maintaining the advantageous features of the second-stage DC-DC converter. Consequently, the system performance is significantly improved. The simultaneous realization of soft-switching and CCM is accomplished by transferring a small portion of current from the transformer of the DC-DC converter to the boost inductor current of the front-end bridgeless PFC rectifier, creating a ZVS condition for the switches in the front-end bridgeless PFC rectifier. A 240-W prototype is used to validate the proposed concept.