Power factor correction control circuit for reducing EMI (electro magnetic interference)

Abstract

The invention discloses a power factor correction control circuit for reducing EMI (electro magnetic interference), which comprises an inductive current threshold value, wherein when an inductive current is less than the inductive current threshold value, a peak value of the inductive current is controlled to be changed along with an input voltage; and when the inductive current reaches the inductive current threshold value, the inductive current is limited to be the inductive current threshold value. In such a way, the maximum peak of the inductive current is reduced, so that an inductive ripple current is reduced; the power factor is ensured, and the EMI of the circuit is reduced simultaneously, so that circuit filtering can be carried out simply and easily; and the power factor correction control circuit is extremely suitable for occasions with middle or low power. In addition, the peak current stress of the circuit is low, so that a switch tube and other components have small loss, and the utilization ratio of a power supply is further improved. The power factor correction control circuit for reducing the EMI disclosed by the invention meets the requirements of high-power factor and IEC61000-3-2 on the harmonic of the power supply, and has low cost and a small size.

Description

technical field [0001] The invention relates to the field of power supplies, and more specifically relates to a power factor correction control circuit for reducing EMI. Background technique [0002] In the application of AC / DC power supply, in order to achieve high power factor, a power factor correction (Power Factor Correction, PFC for short) function is usually designed in the circuit. Currently, a critical conduction mode power factor correction circuit is more commonly used. From the perspective of implementation, there are two solutions for the existing critical conduction mode: one is the peak current mode, and the other is the voltage mode. The former scheme uses the peak value of the modulated inductor current to follow the change of the input voltage signal to realize the sinusoidalization of the input current and achieve the purpose of being in phase with the input voltage; the latter scheme uses to keep the conduction time constant throughout the line cycle , t...

AI Technical Summary

Problems solved by technology

from figure 1 It can be seen that the disadvantage is that the peak value of the inductor current is high, which will make the inductor ripple current larger, resulting in the need to strengthen the electromagnetic interference (EMI) filter in the circuit, increasing the input EMI Complexity of Filter Circuits

Moreover, the higher peak current will make the conduction loss of the semiconductor device larger

Therefore, in low-to-medium power applications, if you want to get the best performance, it will inevitably result in high cost and large volume, which is not easy to popularize and use.

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