Abdelkader Benabou

Comparison of Preisach and Jiles–Atherton models to take into account hysteresis phenomenon for finite element analysis

Abstract In electrical engineering, study and design of electromagnetic systems require more and more accurate models. To improve the accuracy of field calculation code, hysteresis phenomenon has to be taken into account to model ferromagnetic material. This material model has to be accurate and fast. In that context, two macroscopic models are often used: the Preisach and the Jiles–Atherton (J–A) models. In this paper, both models are presented. Field calculation requires a model giving the magnetization M versus either the magnetic field H or the magnetic flux density B . Consequently, from the classical Preisach and J–A, two sub-models M ( H ) and M ( B ) are deduced. Then, we aim at comparing these models in terms of identification procedure facilities, accuracy, numerical implementation and computational effort. This study is carried out for three kinds of materials, which have different magnetic features: ferrites, FeSi sheets and a soft magnetic composite material. Then, the implementation of these models in a finite element code is presented. As example of application, a high-frequency transformer supplied by a rectangular voltage is studied.

Stochastic Modeling of Soft Magnetic Properties of Electrical Steels: Application to Stators of Electrical Machines

To take account of the uncertainties introduced on the soft magnetic materials properties (magnetic behavior law, iron losses) during the manufacturing process, the present work deals with the stochastic modeling of the magnetic behavior law B-H and iron losses of claw pole stator generator. Twenty-eight samples of slinky stator (SS) coming from the same production chain have been investigated. The used approaches are similar to those used in mechanics. The accuracy of existing anhysteretic models has been tested first using cross validation techniques. The well known iron loss separation model has been implemented to take into account the variability of the losses. Then, the multivariate Gaussian distribution is chosen to model the variability and dependencies between identified parameters, for both behavior law and iron loss models. The developed stochastic models allow predicting a 98% confidence interval for the considered samples.

Finite Element Three-Phase Transformer Modeling Taking Into Account a Vector Hysteresis Model

In this work an approach for modeling a transformer core taking into account magnetic hysteresis is presented. For this purpose, the inverse vector Jiles-Atherton hysteresis model is incorporated in a 2D finite element code. This model allows writing naturally the differential reluctivity tensor which can be directly used in the magnetic field equations. A three-phase transformer is modeled. The excitation characteristics of the transformer, as well as hysteresis loops at specific points, are presented. The proposed model was verified with obtained experimental data.

Three-Phase Transformer Modeling Using a Vector Hysteresis Model and Including the Eddy Current and the Anomalous Losses

This paper presents a 2-D finite-element model to analyze the iron losses in a three-phase transformer. In this model, the effects of nonlinear core behavior are taken into account by means of a vector hysteresis model incorporated in the finite-element formulation by using a magnetic differential reluctivity tensor. The reluctivity tensor emerges naturally from the vectorized Jiles-Atherton model. The complete model includes eddy current losses and the anomalous losses. The magnetization currents are calculated and compared with the measured ones. Calculations of hysteresis loops at spotted points of the transformer are also performed. The comparisons between the iron losses measured and calculated with vectorial hysteresis, including the eddy current and the anomalous losses, are presented.

Adaptive Method for Non-Intrusive Spectral Projection—Application on a Stochastic Eddy Current NDT Problem

The Non-Intrusive Spectral Projection (NISP) method is widely used for uncertainty quantification in stochastic models. The determination of the expansion of the solution on the polynomial chaos requires the computation of multidimensional integrals. An automatic adaptive algorithm based on nested sparse grids has been developed to evaluate those integrals. The adapted algorithm takes into account the weight of each random variable with respect to the output of the model. To achieve that it constructs anisotropic sparse grid of the mean, leading to a reduction of the number of numerical simulations. Furthermore, the spectral form of the solution is explicitly identified from the constructed quadrature scheme. Numerical results obtained on an industrial application in NDT demonstrate the efficiency of the proposed method.

Experimental Characterization of the Iron Losses Variability in Stators of Electrical Machines

Manufacturing processes may introduce a significant variability on the magnetic properties of claw pole generator stators. The present work deals with the analysis of two groups of stator samples. The first group is composed of 28 slinky stators (SS) and the second group is composed of 5 stators, manufactured using laser cut stacked laminations (SL). Both groups are made from the same lamination grade and with the same geometrical dimensions. Characterization was carried out for several levels of excitation field at 50 Hz. A noticeable variability has been observed on the iron losses for SS samples, whereas it appears to be not significant for SL samples. The loss separation technique has then been investigated for the SS samples. Results show that the variability of static losses is more important than the one of dynamic losses.

Transformer Inrush Currents Taking Into Account Vector Hysteresis

Inrush currents have undesired effects on transformers when these ones are, for example, switched into service. Theses effects have to be taken into account when designing a transformer, what leads to a constraint on its magnetic core and size definition. This paper investigates the modeling of inrush currents in a three phase transformer under sinusoidal voltage operation conditions. The transformer core is modeled taking into account the magnetic hysteresis including the anisotropy. Therefore, a Jiles-Atherton vectorized model is used for the nonlinear core modeling. The key advantage of this vector model is its reluctivity tensor which is appropriated for the Finite Element calculations in vector potential formulation. A time-domain simulation was carried out and the results were compared with experimental data for the procedure validation.

Accurate minor loops calculation with a modified Jiles‐Atherton hysteresis model

Purpose – Although the original Jiles‐Atherton (J‐A) hysteresis model is able to represent a wide range of major hysteresis loops, in particular those of soft magnetic materials, it can produces non‐physical minor loops with its classical equations. The purpose of this paper is to show a modification in the J‐A hysteresis model in order to improve the minor and inner loops representation. The proposed technique allows the J‐A model representing non‐centred minor loops with accuracy as well as improving the symmetric inner loops representation.Design/methodology/approach – Only the irreversible magnetization component is slightly modified keeping unchanged the other model equations and the model simplicity. The high‐variation rate of the irreversible magnetization, which causes the non‐physical behaviour of minor loops, is limited by introducing a new physical parameter linked to the losses. Contrarily to other modifications of the original model found in the literature, the previously knowledge of the mag...

Implementation of an Anisotropic Vector Hysteresis Model in a 3-D Finite-Element Code

The implementation of a vector hysteresis model in 3-D finite-element magnetic field calculation is performed. The vector model is derived from the original scalar Jiles-Atherton one. The hysteresis model has been implemented in a 3-D vector potential formulation. The nonlinear equation system is solved using the Newton-Raphson method. A comparison between measured and calculated results is performed.

Calculation of Iron Losses in Solid Rotor Induction Machine Using FEM

This paper presents a study on iron loss estimation for a solid rotor induction motor fed by pulsewidth modulated supply. The iron losses are often determined using an a posteriori method that can lead to more or less important deviations, compared with measurements, depending on the used models and implementation techniques. The methodology proposed here consists of computing the iron losses with an analytical method implemented in a post-processing of a 2-D finite-element analysis. Different implementation techniques are used to investigate the impact of the model on the iron loss.