Power factor correction control circuit capable of reducing EMI

Abstract

The invention discloses a power factor correction control circuit capable of reducing EMI. The control circuit comprises an inductive current threshold value, the peak value of the inductive current is controlled to change along with the input voltage when the inductive current is smaller than the inductive current threshold value, and the inductive current is restrained to the inductive current threshold value when the inductive current reaches the inductive current threshold value. Therefore, the maximum peak of the inductive current is reduced in the above manner, and the inductive ripple current is reduced. The power factor is guaranteed, at the same time, the EMI of the circuit is reduced, the circuit filter task is conducted simply and easily, and the power factor correction control circuit is suitable for sites of medium power and small power. The peak current stress of the circuit is low, a switch tube and other elements wear little, and the power utilization rate is improved further. The power factor correction control circuit capable of reducing the EMI meets the requirements on power supply harmonics of high-efficient factors and IEC61000-3-2, and is low in cost and small in size.

Description

[0001] This application is a divisional application with the application number 201110289647.7, the application date is September 14, 2011, and the invention title is "A Power Factor Correction Control Circuit for EMI Reduction". technical field [0002] 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 [0003] 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...

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.

Images