EMI filters design for power electronics

EMI filters for equipment, in which power electronic converters are used, often are designed by trial and error. Moreover, the design is carried out taking into account the total noise produced by the equipment. Thanks to the separation of the noise into the differential mode and the common mode components, it is possible to understand which of the two components is dominant and therefore the filters design can be done straightforwardly by directly measuring the necessary common mode and differential mode attenuation. In this way, it is possible to avoid an expensive and useless heavy filter and satisfy the standards limits only by filtering the dominant component using a smaller, cheaper and optimized filter. In this paper, the authors show a five steps design procedure for the design of EMI filters for power electronics equipment. Experimental results for a studied case are given to show the validity of this approach