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Finite element method based electromagnetic modeling of three-phase EMI filters

Finite element method (FEM) based electromagnetic simulation is commonly used for low frequency problems such as motor and transformer design. But it is rarely used for electromagnetic interference (EMI) filters design and analysis. FEM based EMI filters simulation has a number of clear advantages in comparison with conventional approaches. It takes into account mutual couplings and self-parasitics, frequency dependency of permeability can be easy included, values of components can be quickly optimized. In this article a design procedure of a three-phase EMI filter based on FEM simulation supplemented with analytical calculation is proposed. Frequency dependency of permeability, impact of parasitics on insertion losses and mutual coupling between components are taken into account. Differential and common mode insertion losses are represented in accordance with CISPR 17. A complete process of the three-phase EMI filter design and analyses is presented. Use of an optimization tool for further insertion losses improvement is demonstrated.