The effect of power factor correction technology on switching power supply

The power factor correction (PFC) technology can reduce the harmonic pollution of switching power supply and improve the power factor of AC-DC switching power supply.

Since the pre-circuit of the switching power supply is usually a rectifier circuit composed of diodes and a filter circuit composed of capacitors, it is the combined effect of the nonlinearity and capacitance of the rectifier diode that distorts the input current - no longer a sine wave, but contains a large number of harmonics, which inevitably leads to a low power factor of the power supply. What is more serious is that when a large number of switching power supply loads are connected to the public power grid, it will produce quite serious harmonic pollution to the power grid.

Therefore, in order to promote "green power supply", power factor correction technology was introduced in the 1990s, that is, the PFC circuit was added between the rectifier circuit and the filter capacitor, so that the input current can track the input voltage, and the sine wave of the input current is not distorted, so that the power factor of the power supply is increased to 99%. In this way, not only the harmonic pollution of the power grid is controlled, but also the overall efficiency of the switching power supply is improved.