Stray capacitance modeling of inductors by using the finite element method

Stray capacitance modeling of an inductor is essential for its accurate equivalent circuit modeling. The stray capacitance determines the inductor's performance and upper frequency limit. In this paper, a method is proposed for modeling the distributed stray capacitance of inductors by the finite element method and a node-to-node lumped capacitance network. The effects of the wire insulation layer, ferrite core, the number of segments used to model the circumference of the wire cross section, the pitch and coil-to-core distances, and the capacitance between non-adjacent turns, etc., on the inductors' self-capacitance and calculation accuracy, have all been considered. The calculated equivalent lumped stray capacitance for a rod inductor with ferrite core is compared to that estimated from measurement. Good agreement between them has been observed.