Design of Magnetic Components for EMI Protection

This paper presents the design of a ferrite EMI suppressor consisting of commercially available ferrite toroids wound with the appropriate number of turns. Measurements of the electrical characteristics of the EMI suppressors (inductance, resistance, and impedance) were performed using an impedance analyzer HP4194A in the range from 100 Hz to 40 MHz, as well as the losses introduced by the magnetic component in the circuit, i.e. <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$S_{21}$</tex> parameter using the spectrum analyzer Siglent SVA1032X. A magnetic component model comprising linear R, <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$L$</tex>, and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$C$</tex> elements is proposed. The impedance values measured and obtained using the proposed model were compared, and a good match was found in the frequency range of interest, up to 40 MHz.