Conference Agenda

In general, the magnetic characteristics of magnetic materials can be expressed by the relationship between the magnetic flux density vector and the magnetic field strength vector. The magnetic flux density vector and the magnetic field strength vector are rarely parallel but mostly have a spatial phase difference angle between them. Therefore, modeling of magnetic hysteresis characteristics for magnetic characteristic analysis needs to represent this relationship. For that purpose, the magnetic properties obtained by the conventional magnetic property measurement method are insufficient, and then a vector magnetic property measurement method that can measure vector behavior is necessary. three components. Vector magnetic characteristics complete the duality between the electrical properties (voltage, current, power factor angle) and the magnetic properties (magnetic flux density, magnetic field strength, spatial phase difference angle) of electrical devices. This paper presents a vector hysteresis loop that replaces the conventional hysteresis characteristic (scalar hysteresis loop).

The parameter identification of energy-based hysteresis models is extremely important regarding the accuracy of simulation results of e.g. electrical machines and transformers. This paper aims to propose an extended version to existing parameter identification techniques in order to correctly depict rotational losses which vanish for high saturation levels. On the basis of measurements obtained by a rotational single sheet tester (RSST), the measured magnetic field strength is split into its reversible and irreversible part. Using this information the parameters of an adapted vector hysteresis model are identified by means of a least squares minimization. The model results are compared to the measurements and show a good agreement concerning the vanishing rotational losses and the behaviour of the magnetic flux density.

The effect of mechanical stress on hysteresis losses of electrical steel sheets is investigated in this paper. Experimental data obtained from a dedicated bench is used on a curve fitting procedure to analyze the parameters behavior for a hysteresis losses model over a range of mechanical compressive and tensile stresses. By applying the concept of equivalent stress, a finite element model is simulated and the hysteresis losses are a posteriori calculated considering an equivalent stress distribution over a single-phase induction motor stator.

In a previous work, a model based on the use of Gaussians and allowing to account for both the non-linear and anisotropic behavior of non oriented and grain oriented electrical steel along any magnetization direction was proposed.

One of its relevant advantages lies in the very limited number of experimental data that are required for it to be fully defined.

However, a balance between the number of experimental data and the accuracy has to be found.

This communication deals with a sensitivity analysis of the parameters defining the model, with an emphasis on the kind of experimental data that has to be chosen in order to lead to the most accurate results.

The paper "Prediction of Core Loss in Transformer Laminated Core under DC Bias Based on Generalized Preisach Model" was moved to PO2.

Real-time magnetic core condition monitoring is a promising technique for rapid fault detection. In this domain, significant progress is forecasted by achieving precise local measurements. In this study, an innovative solution is proposed to measure local magnetic properties, which is adapted to real-time monitoring and magnetic circuit evaluation. The sensor capability was validated both experimentally and through simulation. Besides the innovative sensor, this study provides a local validation of the most advanced high-fidelity simulation method. It can be used to predict the responses of magnetic cores and electromagnetic converters to defects of various natures, as well as geometrical and property changes.

This paper performs numerical and experimental studies on laminated magnetic cores with GO electrical steels, subjected to inter- laminar short circuit faults. Accurate time-domain finite element (FE) models allow visualizing inter-laminar eddy currents caused by inter-laminar core faults (ILFs), estimating the effect on the dynamic hysteresis loops, and computing the additional eddy current power loss. To support the FE modelling, experimental works were also performed on stacks of four Epstein size laminations under controlled sinusoidal magnetisation at power frequency of 50 Hz and peak flux densities of 1.0 to 1.7 T. The original contribution of this work is the characterisation of lamination stacks with ILFs by both highly accurate 3D FE simulations and experimental results. The local and global results of the former corroborate the measurements, aiming at magnetic core structural healthy monitoring.

This paper presents the study on the vibration characteristics of the iron core transformer due to the magnetostrictive effect. Firstly, to make the simulation model of the transformer core reflects the real state of the transformer core entity with high fidelity, a microdomain-based macroscopic thermodynamics method is used to modify the magnetostrictive intrinsic model for the grain-oriented silicon steel sheet in power transformers. The results indicate that the modified model can increase the accuracy of magnetostrictive values by 33% compared with the existing model. Finally, a 3D vibration model of the transformer core is established based on the modified model and elasticity theory. The magnetic field distribution, magnetostrictive force, and vibration amplitude of the core are calculated.

In high-frequency electromagnetic field analysis using the 3-D finite element method, the simultaneous equations may not be solved if the material with high magnetic permeability is in the analyzed region. Numerical experiments are carried out on the magnetic permeability of the material in the high-frequency electromagnetic field. In this paper, the relationship between the permeability and the field frequency is clarified.

This paper presents analysis of eddy-current power loss in heat pipes (HPs) for integrated thermal management of electrical machines. Here, a close integration of HPs with winding body is considered. Such an arrangement is particularly attractive, as it targets the main heat source within the machine assembly. However, there are several challenges associated with the subsystem compatibility, which include electromagnetic, thermal, and mechanical design aspects. The HP’s power loss, which is generated as a results of the time varying stator and/or rotor slot magnetic flux leakage, requires careful considerations. Although, the HP-enabled thermal management of electrical machines (electrical windings) has been previously investigated, the additional HP generated power loss has had a very little attention. In this work, the author explores alternative techniques for accurate predictions of HP generated power loss accounting for the HP’s wick structure. Two alternative HP constructions Copper-Water and Titanium-Water with sintered and mesh wicks have been investigated in this analysis. Both theoretical finite element (FE) electromagnetic and experimental methods are discussed in detail. The results suggest that the experiment informed FE model of HP with an equivalent electrical resistivity wick region provides an accurate HP representation useful in design of electrical machines.

This work presents a novel method to obtain a B-spline surface based Everett map, for application in the Preisach model of hysteresis, to predict static hysteresis behavior in NO27-1450H motor steel. The novelty of the method stems from its ability to directly capture the Everett map as a closed-form B-spline surface expression, while simultaneously eliminating model artifacts that plague Everett map based Preisach models. Contrary to other works, that applied numerical descriptions for the Everett map, the presented approach is of completely analytic nature. In this work the B-spline surface fitting procedure and the necessary constraints are explained. Furthermore, the B-spline based Everett map was validated by ensuring that any physically meaningless artifacts were properly eliminated. Additionally, the model output was comparing to a measured arbitrary benchmark excitation, which it was able to reproduce with high accuracy.

The industry promotes nondestructive testing methods based on magnetization mechanisms. Amongst multiple signatures, magnetic incremental permeability shows promising results. In this domain, main industrial developments came from experimental observations, which limit understanding and further exploitation. In this study, we combined the Jiles-Atherton and the Dodd & Deeds models to simulate the magnetic incremental permeability. Good comparison simulations/measurements validated the approach. The resulting simulation method provides theoretical frame and gives access to predictive behaviors.