Electromagnetic Compatibility (EMC) debugging of power electronics systems depends heavily on the experience of specialists due to the complex mechanisms of electromagnetic noise. In this paper, the time domain approach is used instead of the conventional frequency domain method to identify noise propagation path. The proposed test mode switches the upper or lower transistors of the converter legs simultaneously on and off at a 50% fixed duty ratio. It is called common mode test mode. Because there is no significant functional current flowing, the differential mode noise is minimized and the remaining common mode noise and mixed mode noise are maximized. Therefore, the common mode noise in this test method gives its upper boundary of Electromagnetic Interference (EMI) level when the system is normal operated. A motor drive system is measured to show how this test mode works.@en

Filters used in electromagnetic interference suppression are often described in literature on drive systems and have become a standard solution in industry. The effect of the commercial off-the-shelf filter depends significantly on how it is installed. A model that includes the installation parameters is made first and then the parameters of the model are extracted by transfer ratio measurements. One possibility is to include the filter on the dc-bus inside the converter. The differential mode DC-bus filter is well known, but the common-mode DC-bus filter has received little attention. Our model is used to show that the common-mode DC-bus filter can achieve the same or even better suppression of common-mode noise by careful design. The transfer ratio is used to evaluate the performance of filter design.@en

In this paper, a novel method for EMI (electromagnetic interference) level prediction is proposed. The method is based on the hierarchical structure of the generation of EMI. That is, the determination of EMI level can be divided into three levels, namely the functional level, the transient level and propagation level. The lower level provides parameter values for the higher level. That makes the analysis to be a single direction chain. In functional level, the working points are obtained. Through transient level analysis, the exact noise sources are determined. In propagation level, the high frequency characteristics in the propagation path are expressed including the variation of parasitic parameters. Frequency analysis can be used to get the EMI level measured in the receiver side rapidly. Because this approach is a straight forward method, the impact of any components can be evaluated immediately instead of doing the simulation from begin to end.@en

Optimization aspects of common mode chokes are presented. These are based on a behavioural model for common mode chokes and its sensitivity study. Results are used to show the influence of the designable parameters on the final performance of the choke placed in a circuit.@en

Abstract¿A galvanically isolated three-phase AC/AC converter with a high-frequency AC-link has been analyzed from an EMC point of view. This is a special configuration because of a large number of switches, a high frequency transformer, and a fourwire output. The essential coupling paths are identified. Corresponding suppression remedies are given. The results, before and after measures, have been presented to demonstrate the improvement in EMC. Keywords: AC/AC converter; electromagnetic interference; galvanically isolated@en