A New PFC Front End With Constant DC-Link Voltage, Reduced Buffer Capacitance, and Soft Switching

Critical conduction mode (CRM) boost power factor correction (PFC) front end is one of the most popular solutions to universal ac–dc applications below 300 W for its simplicity and high efficiency. However, its power density is largely limited by the need for a relatively bulky inductor and a buffer capacitor. This article introduces a new PFC front end that enables simultaneous size reduction of both the inductor and the buffer capacitor by achieving zero-voltage-switching of all switches and active power buffering. A 100-W universal input prototype is built, measuring a 96.7% peak efficiency and 50.8-W/in$^{3}$ power density. Compared to a typical CRM boost PFC front end, the prototype achieves a 47% size reduction of the magnetics, a 21% size reduction of the buffer capacitor, and an almost constant dc-link voltage, while maintaining comparable efficiency performance.