A 500 kHz, 3 kW power factor correction circuit with low loss auxiliary ZVT circuit

The paper presents a low-loss auxiliary circuit in a power factor correction (PFC) circuit to achieve zero voltage transition and hence improving the efficiency and operating frequency. The high dynamic energy generated in the switching node during turn-on is diverted by providing a parallel path through an auxiliary inductor and a transistor placed across the main inductor. The auxiliary devices operate at zero current switching and this addition has no effect on the control of the main PFC circuit. The paper discusses the operating principles, design and merits of the proposed scheme with hardware validation on a 3 kW/ 500 kHz PFC prototype.