Measurement equipment and optimal approach for power line filter design for automotive

Electromagnetic compatibility (EMC) standards set limits on the maximum conducted emissions (CE) interferences that can be generated [1 –3]. The most common solution to reduce the interferences is to use a power line filter (PLF) [4–11]. Most of the EMC engineers, in lack of the correct equipment to measure the modal emissions, design power line filters (PLF) by using commercial PLFs that provide acceptable results when used with legacy products or by using a new filter after a long trial-and-error process. This, since commercial EMI receivers cannot separate the common mode (CM) and differential mode (DM). This paper presents an overview and comparison of the existing receivers available in the market and a process that should be followed to design an optimal PLF, both in terms of size and cost. Real measurements on two different equipment under tests (EUTs) are presented to show the advantages of the proposed approach. The method presented in the paper can be applied to automotive vehicle testing and extended to three phase system. Moreover, it will result suitable for both CE measurements of internal electronic circuitry of EVs and for the CE reduction generated by the charging stations (CSs).