Modeling and Evaluation of DC Superimposition Characteristics of Molded Inductors

The dc superimposition characteristic is a crucial consideration when employing inductors. Taking a molded inductor with dimensions of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$6.6\times 6.6\times 2.88$ </tex-math></inline-formula> (mm) as an example in this study, we utilize equivalent magnetic circuit theory and finite element analysis software and establish the relationship between the dc superimposition characteristic of inductor and the B–H characteristic of its core material. This relationship significantly simplifies the assessment of the direct current superimposition characteristic in the design and development of inductors. Our results indicate that using effective magnetic circuit volume and electromagnetic energy formulas enables the calculation of the equivalent magnetic field intensity in the inductor, thus establishing the correspondence between the inductance (L)–bias current (I) curve of molded inductor and the B–H curve of core material. Through the analysis of the inductor presented in this letter, we determine that each ampere direct current offset can generate an equivalent magnetic field intensity of approximately 1658 A/m within the inductor, and the result is validated through the experimental characterization on our inductor samples.