Electromagnetic Modeling of EMI Input Filters

The paper summarizes a new modeling procedure for 3D virtual design of EMI filter circuits. The proposed method, based on the coupling of the Partial Element Equivalent Circuit (PEEC) and Boundary Integral Method (BIM) methods, extends the standard PEEC approach for modeling in the presence of magnetic materials, hence allowing the PEEC-based modeling of toroidal EMI filter inductors. The PEEC-BIM coupled method is implemented into a 3D CAD PEEC-based virtual prototyping platform (GeckoEMC). The developed EM simulation tool can give a comprehensive understanding of EM behaviour of EMI filter inductors and capacitors, taking their geometrical and material properties into account. Furthermore, it enables the modeling of optimal EMI filter structures including both parasitics and the effects originating from the mutual coupling and the interconnection of filter elements. The approach is verified by impedance and transfer function measurements of different single phase single-/two-stage EMI filter structures. Good agreement between the measurement and the PEEC-based simulation results was achieved for the frequency range from DC up to 30 MHz.