As the switching power supply in the AC / DC converter circuit on the input rectifier components and filter capacitor, sinusoidal voltage input, single-phase rectifier power supply of electronic equipment, power side (AC input) power factor of only 0.6 to 0.65. The PFC (Power Factor Correction) converter is adopted in the power supply so that the network side power factor can be increased to more than 90 percent and the input current THD is less than 10 percent. Harness the harmonic pollution of the power grid, while improving the overall efficiency.
Switching power supply generally high-power AC / DC, mostly PFC converter composed of two topologies, for small AC / DC switching power supply generally use two-stage topology so that the overall efficiency of the power supply low and high cost.
If the input power factor requirements are not particularly high, the switching power supply of the PFC converter and the latter DC / DC converter combination into a topology, constitute a single-stage high power factor AC / DC switching power supply, if only a main switch Tube power supply, the power factor can be corrected to more than eight percent, while making the output DC voltage adjustable.