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Magnetoelectric voltage tunable inductors (VTIs) offer a new paradigm for power electronics circuit design. Here, air-gapped VTIs are demonstrated exhibiting a large inductance tunability of 220% with applied fields under 20 kVcm−1 and operational stability up to 5 MHz that covers the full frequency range of the state-of-the-art power electronics. The design of air-gapped VTI comprises of two C-shaped ferrite cores, one permeability-variable magnetic flux valve (MFV) in between C-shaped cores, and slotted air gap between cores and MFV. The tunability of VTIs is achieved through the electric field modulation of permeability in the MFV based on the magnetoelectric effect. There is a tradeoff between the tunability and saturation current. The introduction of air gap significantly reduces the tunability but provides methodology toward increasing the saturation current and power handling capability due to the increased reluctance. The inductance and tunability reduces by 50% with increase in the air-gap width from 0.07 mm to infinity (condition with no C-shaped cores). Phase field simulations demonstrate that the air gap affects the magnetization, permeability, and tunability of VTIs by tailoring the demagnetization field that further influences the magnetic domain rotation process. VTIs with increased frequency range and saturation current will strengthen the continued development of tunable power electronics. [ABSTRACT FROM AUTHOR]

Abstract Control of magnetic permeability through voltage in magnetoelectric materials promises to create novel voltage tunable inductors. Domain-level phase field modeling and computer simulation are employed to study magnetoelectric composites of Co-modified NiCuZn ferrite and PZT, where ferrite outperforms metallic magnetostrictive materials at high frequencies important for inductor applications. The simulations focus on the interplay between magnetocrystalline anisotropy and stress-induced anisotropy and reveal different regimes of permeability and tunability behaviors. It is shown that the permeability and its tunability can be significantly increased by reducing the intrinsic magnetocrystalline anisotropy through doping NiCuZn-ferrite with Co2+ to form solid solution (1- x)(Ni 0.6 Cu 0.2 Zn 0.2)Fe 2 O 4 - x CoFe 2 O 4 , and the optimal performance is achieved at vanishing magnetocrystalline anisotropy constant K 1 = 0 corresponding to composition x ∼0.02. The findings are confirmed by complementary experiments with good agreements. The effect of internal bias stress is further investigated, which is shown to shift the permeability regimes and thus provides an effective engineering technique to optimize the voltage tunable inductor performance. A tunability as high as ∼500% is obtained under the optimal condition, which is much higher than that obtained in conventional high-frequency voltage tunable inductors. Graphical abstract Image 1 [ABSTRACT FROM AUTHOR]