In effect, the simple rectification technique draws power from the mains supply when the instantaneous line voltage exceeds the bulk capacitor voltage. In practice this occurs for a short period near the line's peak voltage and results in high-charge current spikes. These spikes add to each other and, consequently, the distribution network faces huge peak currents, Neutral currents that are too high for the system may flow in three-phase distribution networks, The harmonic current may produce such severe voltage distortions in a distribution branch that appliances it supplies may not work properly, At any given power, the resulting rms current is almost double it would be with a unity power factor, and the available power that can be drawn is nearly halved. At the same time the power distribution network has to be built oversized to compensate. Generally speaking low power factors degrade the quality and the power capability of the distribution network.
Active solutions are the most popular means to meet the regulations.
A PFC pre-regulator can be inserted between the input bridge and the bulk capacitor. Corrected Power Factor Circuit PFC boost preconverters typically require a transformer, a diode and a power switch, and they also need a power factor correction controller that is a circuit specially designed to drive PFC pre-regulators. ON Semiconductor has developed such drivers to facilitate PFC implementation. The MC33260 offers a synchronization facility for EMI reduction. The MC33260 offers a high robustness to PFC solutions.