Active Power Factor Correction for Switching Power Supplies

The harmonic-free utility/dc interface provides to the computer industry a means to extract more power from the wall outlet than the normal rectifier, with its heavily distorted input current, will allow. Due in part to the very high switch stresses in this interface, however, the cost appears to be too high to justify its use at this time. An alternate approach is proposed that focuses on power factor correction rather than harmonic reduction. Compared to the harmonic-free interface, the switch stress of this new approach is approximately a factor of two smaller.