A Novel Measurement System for the Common-Mode- And Differential-Mode- Conducted Electromagnetic Interference

Abstract

Abstract-Electromagnetic Interference (EMI) test is an important part for the manufacture of power electronic equipment, which helps us not only analyze the noise characteristics of the Equipment Under Test (EUT) but also design EMI filters. The previous separation method for the Common Mode (CM) and Differential Mode (DM) noise was time consuming or costly. In this paper, a novel measurement system for CM and DM conducted EMI is described showing a good performance. The system consists of two parts, part 1: getting CM noise or DM noise through a current probe; part 2: obtaining another mode noise from a software-based method. A 150 w switch mode power supply is measured to verify the proposed measurement system. The noise spectra of CM and DM signal is shown, and the results obtained by software program are compared with those obtained from a current probe measurement showing a good concordance in terms of peak value.