Finite element modeling of an electrically variable inductor

A new type of electrically variable inductor has been investigated. This uses an AC excitation field with an orthogonal DC bias field to control the properties of the device. Measurements showed that the effective inductance can be decreased by increasing the orthogonal DC bias field. With an appropriate current in the orthogonal bias coils, an inductance plateau can be reached in which the inductance remains stable over a range of excitation currents. The inductance value can be adjusted by controlling the orthogonal current. Based on an existing anhysteretic magnetization model, nonlinear 3D finite element modeling was successfully used to model the distribution of flux density and to identify the region of saturation which is believed to result in the decrease in effective inductance of the inductor. The effective inductance of the device was also modeled using numerical finite element calculations. The modeled inductance showed broad agreement with experimental results and predicted the observed trend in inductance.