A Wideband Low-Pass Filter for Differential Mode Distortion

Abstract

This paper deals with the solution for a wideband low-pass filter that can be used for filtering the input currents of switching converters, which are distorted by the switching frequency of PWM. Initially, the filter was proposed for the special type of AC converter, which is described in the paper. However, these solutions can also be used in the inputs of active PFC converters and in the outputs of PWM converters, where there are similar problems with switching frequency.The frequency band of the filter is given by the switching frequency of the filtered device and by the demands of EMC standards. This makes the filter able to work in the frequency band from 10 kHz to 30 MHz. To ensure such a frequency band, the filter should be proposed with two sections, each for a specific part of the band.