Effective magnetization and forces due to eddy currents

Rabinovici, R.; Kaplan, B.Z.

doi:10.1109/20.141296

Cited by 17 publications

(5 citation statements)

References 7 publications

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“…The foundations of any high-fidelity model in the frequency-domain were laid down by Stoll [11], further refined by Feeley [12] to establish the so-called "eddy-inductance", which we used for our flux density estimator. Cylindrical actuators and magnetic bearings were first considered by [13] and [14], respectively, leading to the almost complete model by Zhu et al [4]. In our previous work [1] we presented a full historical review of eddy current models, a study on their physical impact as well as final model refinements.…”

Section: Ementioning

confidence: 99%

Consideration of Hysteresis, Saturation, Fringing and Leakage Fluxes in the Frequency-Dependent Analytical Model of Nonlaminated Cylindrical Actuators

Seifert¹,

Porstmann²,

Hofmann³

2021

Preprint

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Previous works have demonstrated that analytical high-fidelity models of nonlaminated actuators and magnetic thrust bearings cannot just describe the magnetic skin effect inside the solid core, but also be applied directly within the control circuit. By an appropriate rational approximation a digital implementation on a microcontroller becomes possible. However, these approximated models neither considered hysteresis and saturation nor frequency-dependent fringing and leakage fluxes. This article elaborates whether or not these nonlinearities can and should be included in real-time control systems. We present an improved process to map an analytical hysteresis model to a limited measured dataset and discuss the impact of the nonlinear magnetization curve. It leads to a novel fractional-order all-pass filter, modeling the frequency-dependent hysteresis angle for a single load point. Its rational filter form is suitable for implementation in Matlab/Simulink as well as real-time applications. Leakage and fringing fluxes, on the other hand, can be considered with relatively low effort within the original analytical models. The underlying reluctance network is determined by a FE-analysis as well as analytically and reduced to a highly simplified form. Depending on whether the total flux or the force-dependent flux is of interest, the model order may increase significantly and constant correction factors are preferable. <br>

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Section: Ementioning

confidence: 99%

Consideration of Hysteresis, Saturation, Fringing and Leakage Fluxes in the Frequency-Dependent Analytical Model of Nonlaminated Cylindrical Actuators

Seifert¹,

Porstmann²,

Hofmann³

2021

Preprint

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“…By integration one can obtain the magnetic flux Φ and the so-called effective reluctance R meff (Tab. 1 -Zhu, 2005; respectively effective permeability µ reff introduced by Seifert and Hofmann, Mechanical Engineering Journal, Vol.4, No.5 (2017) [DOI: 10.1299/mej.16-00696] Rabinovici et al, 1992). The air gap field represents a special case: even though there are no eddy currents, it is not homogeneous as its width is usually too small (Fig.…”

Section: Advanced Magnetic Circuit Modelmentioning

confidence: 99%

Completion of analytical model of active magnetic thrust bearings including asymmetric air gap field between mixed materials

Seifert

Hofmann

2017

Mechanical Engineering Journal

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The electrodynamics of magnetic thrust bearings are characterized by an above-average dependency on the bearing materials. Axially directed fields render laminated stators and rotors ineffective. High induced voltages inside the magnetic core evoke eddy currents and opposing fields, which are compensated by an additional magnetizing current causing a significant delay between the measurable coil current and the force-related magnetic flux. The control dynamics are hampered and even though this effect can be reduced by the use of Soft Magnetic Composites (SMC) for non-rotating parts, the thrust disk is usually made out of steel due to its superior tensile strength and saturation flux density. The analytical modeling of mixed-material magnetic thrust bearings reveals new challenges arising from asymmetries and low permeable magnetic core sections, both of which are addressed in this article. In case the air gap is bounded by core sections made of different materials the established analytical models are not applicable and require the presented asymmetrical air gap wave propagation constant. Furthermore the consideration of the stator corner reluctances for SMC cores compensates the stationary error of 6 % of the total effective reluctance present in previous works. DisclosureThe following article is an extended version of the conference paper Analytical Asymmetric Air Gap Model for Active Magnetic Thrust Bearings of Mixed Materials Including Eddy Currents by Seifert et al. presented at the 15th International Symposium on Magnet Bearings, 2016. The conference contribution focused on the asymmetric air gap reluctance model, which is required for magnetic bearings consisting of multiple core materials. The low permeability of the deployed soft magnetic composites additionally requires the consideration of the corner elements of the magnetic circuit (Fig. 1b), which have been neglected to date. These considerations are addressed in detail in this article to complete the analytical modeling of active magnetic thrust bearings. However, local saturation effects and frequency dependent leakage fluxes are not considered yet and still subject of further investigations.

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“…Moreover, for dynamically analyzing the aircraft wings with the EIDI system and avoiding the complex calculations of the deicing excitation, Labeas et al depended on simplifying the load distribution which was assumed to be constant at the coil area and decreased linearly to zero at a distance 150% of the radius of the coil [6]. Furthermore, researchers in the eddy current fields mainly take interest in the total magnetic forces acting on the targets [7].…”

Section: Introductionmentioning

confidence: 99%

Deicing Excitation Simulation and Structural Dynamic Analysis of the Electro-Impulse Deicing System

Bai

Zhu

2011

AMM

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A two-dimensional electromagnetic eddy current field analysis model of the experimental electro-impulse deicing system (EIDI) is developed. Additionally, a numerical post-processing method is proposed to calculate the deicing excitation exerting on the testing skin. Moreover, a three-dimensional dynamic analysis finite element model of the testing skin loaded the excitation is built for evaluating the response accelerations. Then, the calculated accelerations are compared with the experimental measured data to validate the correctness of the proposed methods. It is obtained that the results agree well, which indicates that it is feasible to use the method of post-processing pressure distribution for solving the deicing excitation and the method of structural dynamic finite element analyzing the testing skin for simulating dynamic response. The presented methods pave a way for ice failure analysis of the EIDI system.

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Effective magnetization and forces due to eddy currents

Cited by 17 publications

References 7 publications

Consideration of Hysteresis, Saturation, Fringing and Leakage Fluxes in the Frequency-Dependent Analytical Model of Nonlaminated Cylindrical Actuators

Consideration of Hysteresis, Saturation, Fringing and Leakage Fluxes in the Frequency-Dependent Analytical Model of Nonlaminated Cylindrical Actuators

Completion of analytical model of active magnetic thrust bearings including asymmetric air gap field between mixed materials

Deicing Excitation Simulation and Structural Dynamic Analysis of the Electro-Impulse Deicing System

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