High frequency simulation of multi-layer air core solenoids using FEM analysis

Air core solenoids are used widely as low-pass or band-pass filters in high volt-age applications. To design a suitable solenoid with the desired Frequency Response (FR), a valid simulation model is required. The models typically used for this purpose are valid up to 1 MHz; however, in some cases, the behavior of such filters may be required in higher frequency ranges. This paper presents a detailed model for the multi-layer solenoid wind-ings which is valid up to 5 MHz. To increase the model accuracy in the High Frequency (HF) ranges, the circuit elements of the model are calculated using the Finite Element Method (FEM). Additionally, the influence of the electromagnetic phenomena at high fre-quencies is investigated in FEM analysis. Moreover, in the case of multi-layer solenoids, the influence of the winding direction of different layers on the FR are investigated. To validate the simulation methodology, some solenoid windings are manufactured and sub-jected to Frequency Response Analysis (FRA) tests. Subsequently, the simulated and meas-ured frequency responses of the windings are compared.