•Reproduction of vector magnetization processes in Fe-Si laminations via VPM and EBM.•Experimental measurements of scalar, rotational and elliptic loops via SDT apparatus.•Models identification using ...a minimal set of experimental hysteresis loops.•Models validation and comparison by the simulation of the 2-D experimental data.•Estimation of the energy losses and verification of the rotational loss property.
The paper presents the state of the art and the problems already open in modelling the hysteresis phenomenon in 2-D for laminated soft ferromagnetic materials. Firstly, a thorough experimental investigation has been carried out at a very low frequency by a single disk tester (SDT) for a specimen of innovative NGO electrical steel sheet. Scalar, rotational and elliptic magnetization processes have been experimentally measured under controlled waveforms of the magnetic induction vector thanks to an effective digital feedback algorithm. Two numerical model of hysteresis have been taken into account to reproduce the measured magnetization processes: the vector Preisach model (VPM) and the Energy Based Model (EBM). The main advantages and limitations in the use of the two hysteresis models are comprehensively analysed and discussed, taking into consideration both the problem of identification and the simulation results. In particular, the effective capability of the models to reproduce the vector field trajectories and to predict the hysteresis power losses has been shown. Conclusive considerations involve the memory usage and the computational time for the low level of abstraction implementation of the two hysteresis models.
This paper presents a novel numerical approach to simulate lightning strike damage to equipotential bonding interfaces of wind turbine blades, and model validation based on high-current testing. ...Modern rotor blades are equipped with metal receptors to intercept the lightning leader and metal down conductors to conduct the lightning current, preventing the direct attachment to the CFRP spars. In such conditions, damage in the form of resin thermal degradation and sparks develop inside the blade at the equipotential bonding interfaces. Excellent correlation was found between the numerical predictions and test results in terms of current and temperature distributions. High temperatures were predicted at the sparking areas observed in the tests, which suggested that the damage is thermally activated. Thermogravimetric analysis data indicated that the epoxy pyrolysis process evolves in stages, and that sparking events are often initiated by release of gases and formation of small voids at temperatures lower than expected.
Spin-Hall oscillators (SHO) are promising sources of spin-wave signals for magnonics applications, and can serve as building blocks for magnonic logic in ultralow power computation devices. Thin ...magnetic layers used as "free" layers in SHO are in contact with heavy metals having large spin-orbital interaction, and, therefore, could be subject to the spin-Hall effect (SHE) and the interfacial Dzyaloshinskii-Moriya interaction (i-DMI), which may lead to the nonreciprocity of the excited spin waves and other unusual effects. Here, we analytically and micromagnetically study magnetization dynamics excited in an SHO with oblique magnetization when the SHE and i-DMI act simultaneously. Our key results are: (i) excitation of nonreciprocal spin-waves propagating perpendicularly to the in-plane projection of the static magnetization; (ii) skyrmions generation by pure spin-current; (iii) excitation of a new spin-wave mode with a spiral spatial profile originating from a gyrotropic rotation of a dynamical skyrmion. These results demonstrate that SHOs can be used as generators of magnetic skyrmions and different types of propagating spin-waves for magnetic data storage and signal processing applications.
The single hysteron model is identified to reconstruct the magnetization processes of a grain-oriented electrical steel and it is implemented in a finite-element scheme. The model involves the Zeeman ...energy and the anisotropy energy of the material and an interaction field to take into account others terms, such as the magnetoelastic energy, the exchange energy, inclusions, and crystallographic discontinuities. The interaction field is evaluated experimentally using a round rotational single sheet tester, where a disk sample of the material is excited for several rotational magnetization processes. Details about the finite-element scheme, the computational time, and the memory allocations involved in the simulations are presented and discussed.
This article aims to investigate the accuracy in modeling and characterization of the dynamic energy loss of modern laminated electrical steels in use for power electronics applications. Measurements ...by an Epstein Frame are performed in case of sinusoidal and non-sinusoidal waveform of the magnetic induction, at different frequencies and peak values. The Steinmetz and the time domain statistical loss theory, either in frequency domain are used, and the related parameters are fitted experimentally. The dynamic energy loss is also modeled and estimated by means of a finite element method (FEM) formulation in time domain, coupled with a vector Preisach model to represent the constitutive law of the magnetic material. The series of the results reported indicates effectiveness and limitations of the modeling approaches considered. Some considerations about the excess loss are also given.
In this paper, a technique based on contactless magnetic measurements is described to evaluate the orientation of the crystal grains in grain-oriented ferromagnetic materials. It is shown that both ...the orientation of the major easy axis, with respect to the rolling direction, and the angle of the out-of-plane axes with respect to the lamination plane, could be evaluated from non-invasive magnetic measurements by the analysis of the lag angle plots. The measured data have to be compared with the simulations of the single grain to estimate its orientation from the measured effects of the local in-plane magnetic anisotropy.
In this paper we propose a computational procedure to simulate the magnetic behavior of inductive blocking devices for the mitigation of the induced voltage and current pulses on the aircrafts ...circuits during a lightning shock. The non linear and hysteretic phenomenon are simulated using a model based on the Preisach theory and implemented in a finite difference scheme in time domain. Using this procedure the performances of the blocking devices can be computed and optimized according to the standard requirements for avionic applications. A dedicated pulse generator is designed and realized for the experimental tests in order to compare numerical results and measurements.
•Fast and accurate algorithm for computing the six parameters required by CEC database.•Reducedform utilized to characterize the onediode circuital model of PV cells.•Formulation computationally more ...efficient than the current model.•Validation on all PV modules currently available at the CEC database.•Comparison with System Advisor Model (US NREL) simulations.
This paper proposes a fast and accurate algorithm for the computation of the six parameters required by the California Energy Commission (CEC) six parameter photovoltaic (PV) module model (CEC6PPVMM). An up-to-date database of module characteristics is very important in both the field of scientific research and industry applications. Currently, adding new PV modules to the CEC database requires the computation of the six parameters at Standard Reference Codition by using few data available in manufacturers’ datasheet. This is usually done by solving complex nonlinear systems using general purpose equation solvers or suitable heuristic methods that, however, are sometimes unable to achieve high levels of accuracy or may feature a strong computational cost. The algorithm proposed herein is based on a reduced-form of the nonlinear system of equations utilized to characterize the one-diode circuital model of PV cells. Important theoretical insights about the solution’s uniqueness and feasible domain are discussed throughout the paper. The algorithm has been verified by identifying the CEC parameters of all PV modules currently available at the CEC database.
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