In recent years, power factor correction
(PFC) for the lagging power factor has been gaining momentum. While the U.S. does not have any existing regulatory requirements, in Europe, the employment of PFC in power supplies is necessary to meet the European EN61000-3-2 regulatory standard. As the U.S. government continues to emphasize energy conservation and efficiency, the domestic need for PFC is on the horizon. While many design considerations exist for a PFC circuit, the design of PFC magnetics hinge upon a few key parameters. Precision Inc. has created a checklist to demystify these parameters and ensure that key design considerations are addressed.
Power factor is the ratio of the real power to apparent power. Power factor can vary between 0 and 1, and can be either inductive (lagging, pointing up) or capacitive (leading, pointing down). In order to reduce a capacitive (or leading) power factor, an inductor is added to make the power factor equal 1. The whole purpose of making the power factor equal to one is to make the circuit look purely resistive (apparent power equal to real power).
If Alternative control power is available, the PFC boost inductor does not require an auxiliary winding.