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The paper explores the use of the magnetic control strategy for the output power regulation of an LCC‐S compensated inductive wireless power transfer system. The magnetic control is implemented through a controlled variable inductor whose magnetization state is actively regulated by an auxiliary DC–DC converter. The principles for the design and regulation of the system are discussed, and the experimental setup for the validation of the regulation method is implemented. Several measurement results highlight the effectiveness and potential improvements of the magnetic control strategy for inductive wireless power transfer systems. [ABSTRACT FROM AUTHOR]

CoO-doping is known to stabilize the temperature dependence of initial permeability and magnetic losses in Mn-Zn ferrites, besides providing, with appropriate dopant contents, good soft magnetic response at and around room temperature. These effects, thought to derive from the mechanism of anisotropy compensation, are, however, poorly assessed from a quantitative viewpoint. In this work, we overcome such limitations by providing, besides extensive experimental investigation vs frequency (DC–1 GHz), CoO content (0 ≤ CoO ≤ 6000 ppm), and temperature (−20 °C ≤ T ≤ 130 °C) of permeability and losses of sintered Mn-Zn ferrites, a comprehensive theoretical framework. This relies on the separate identification of domain wall motion and moment rotations and on a generalized approach to magnetic loss decomposition. The average effective anisotropy constant ⟨Keff⟩ is obtained and found to monotonically decrease with temperature, depending on the CoO content. The quasistatic energy loss Wh is then predicted to pass through a deep minimum for CoO = 3000–4000 ppm at and below the room temperature, while becoming weakly dependent on CoO under increasing T. The rotational loss Wrot(f) is calculated via the complex permeability, as obtained from the Landau-Lifshitz equation for distributed values of the local effective anisotropy field Hk,eff (i.e., ferromagnetic resonance frequency). Finally, the excess loss Wexc(f) is derived and found to comply with suitable analytical formulation. It is concluded that, by achieving, via the rotational permeability, value and behavior of the magnetic anisotropy constant, we can predict the ensuing properties of hysteresis, excess, and rotational losses. [ABSTRACT FROM AUTHOR]

We have studied ways of predicting power losses in soft magnetic laminations for generic time dependence of the periodic magnetic polarization J(t). We found that, whatever the frequency and the induction waveform, the loss behavior can be quantitatively assessed within the theoretical framework of the statistical loss model. The prediction requires a limited set of preemptive experimental data, depending on whether or not the arbitrary J(t) waveform is endowed with local slope inversions (i.e., minor hysteresis loops) in its periodic time behavior. In the absence of minor loops, such data reduce, for any peak polarization value [J.sub.p], to the loss figures obtained under sinusoidal J(t) at two different frequency values. In the presence of minor loops of semiamplitude [J.sub.m], the two-frequency loss experiment should be carried out for both peak polarization values [J.sub.p] and [J.sub.m]. Additional knowledge of the quasi-static major loop, to be used for modeling hysteresis loss, does improve the accuracy of the prediction method. A more general approach to loss in soft magnetic laminations is obtained in this way, the only limitation apparently being the onset of skin effect at high frequencies. Index Terms--Eddy currents, magnetic losses, Preisach models of magnetic hysteresis, soft magnetic materials.

This paper presents the implementation of an isotropic vector hysteresis model within a two dimensional time periodic Finite Element procedure, formulated in terms of magnetic vector potential. The standard Vector Preisach Model is employed and an identification procedure based on the scalar Preisach distribution function is used. Nonlinearity is handled by means of the Fixed Point technique following the H-convergence scheme. The convergence of the procedure is assessed and the results obtained are discussed. Index Terms - Vector hysteresis, Material modelling, Finite element field computation.

A thermometric-fieldmetric method is developed by which Fe-Si laminations are characterized under either alternating or rotational excitation up to peak induction. The power losses at high inductions are determined by measuring the rate of rise of the specimen temperature and the imperfect adiabatic behavior of the material is accounted for by the physical modeling of the thermal diffusion process.

In this paper, a novel numerical time-stepping scheme for the solution of the dynamic Landau- Lifshitz equation of micromagnetics is introduced. The equation is a non-linear problem, and is traditionally solved using semi-discretization techniques. However, these techniques corrupt some intrinsic properties of the Landau-Lifshitz (LL) dynamics such as the conservation of magnetization magnitude in time. The proposed approach uses a mixed mid-point Runge-Kutta like algorithm which satisfies LL dynamic properties for time-steps up to 1.25 ps. The accuracy of the proposed scheme has been tested and verified using lmag Standard Problem 4 against popular micromagnetic simulation software for different time-steps and cell sizes. [ABSTRACT FROM AUTHOR]