Design of Soft Ferrite filters for EMI reduction in Power Conversion Systems

The use of a discrete passive filter is the most attractive solution for EMI reduction in power conversion systems. This is due to its simplicity of concept and efficiency in the frequency range up to tens of megahertz and over. The common mode and differential mode sections of the EMI filter contain capacitors and soft magnetic chokes and, when they are used in the transportation context, their design has to satisfy further constraints in terms of low weight, low volume, low losses and low cost in adjoint to filtering efficiency. In this framework the authors, by using an EMI filter design procedure already setup by themselves, investigate, also with an experimental setup, the possibility of evaluating the performance of the soft ferrite components, from the losses point of view.