PFC (power factor correction) control method with high input power factor and control circuit thereof

Abstract

The invention provides a PFC (power factor correction) control method with high input power factor and a control circuit thereof. The method comprises the steps of controlling a switching tube to be switched on and switched off according to the principle of leading impulse area to be equivalent, and leading input inductive current and sinusoidal half-wave current to have the equivalent impulse area in each switching period, thereby realizing the high power factor (PF); furthermore, the higher the switching frequency, the closer to 1 the PF value is. In the control circuit, a circuit topological structure of a Boost converter and a control circuit for realizing a variable duty ratio sequence jointly constitute a PFC stage of a commonly used LED (light-emitting diode) driving power supply, the front stage of the PFC stage is connected with the output end of a non-controllable rectifier bridge of a single-phase diode via an input filter capacitor, the back stage of the PFC stage is connected with a DC / DC (direct current / direct current) stage of the commonly used LED driving power supply via an output filter inductor and an output filter capacitor. By adopting the PFC control method, not only the very high input power factor can be realized, but also output voltage ripple can be reduced; furthermore, the control circuit is simple and easy to realize an analog circuit, thereby being conductive to large-scale integration.

Description

technical field [0001] The invention relates to a single-phase power factor correction circuit in the field of switching power supplies, in particular to a PFC control method with high input power factor and a control circuit thereof. Background technique [0002] When the traditional AC-DC conversion circuit is running, the power factor of the grid side is generally around 0.6~0.7, and a large amount of harmonic current will be generated, which will cause serious harm to the grid. In order to meet the requirements of high power factor and suppression of harmonic generation, a PFC stage with power factor correction function is usually added. The PFC stage is a DC / DC switching converter added between the rectifier and the load. The voltage and current feedback technology is applied to make the waveform of the input current close to a sine wave to improve the power factor. According to the different requirements of different loads on the voltage, it is usually necessary to ad...

AI Technical Summary

Problems solved by technology

[0006] The purpose of the present invention is to provide a high input power factor PFC control method, using the principle of equal impulse area to obtain a variable duty cycle control sequence that can achieve high power factor, and solve the traditional PFC control method. The problem of complexity and low precision , while improving the power factor, it also obtains smaller output voltage ripple and higher efficiency

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