Low cost power factor correction (PFC) converter using delay control

A low cost universal input voltage (90/spl sim/264 V) power factor correction (PFC) converter for a 200 W power supply in a personal computer (PC) is proposed. It consists of the PFC part followed by a DC-DC power converter as in a conventional two-stage scheme. However a single PWM controller is used as in a single-stage, single-switch PFC scheme. The switch in the PFC part is synchronized with the switch in the DC-DC power converter and it has a fixed frequency. Employing a simple delay scheme using the pulse and feedback signal of the DC-DC power converter, the PFC switch is controlled to limit the capacitor voltage within a range for the optimum efficiency and cost. A tradeoff study shows that it indeed offers better efficiency and cost reduction compared to single switch approaches for this power level. The design procedure and experimental results are presented.