scholarly journals Prediction of Eddy Current Losses in Cooling Tubes of Direct Cooled Windings in Electric Machines

Mathematics ◽  
2019 ◽  
Vol 7 (11) ◽  
pp. 1096 ◽  
Author(s):  
Mohamed Nabil Fathy Ibrahim ◽  
Peter Sergeant
Keyword(s):  
Magnetic Field ◽  
Finite Element ◽  
Eddy Current ◽  
Electric Machines ◽  
Iron Core ◽  
Commercial Software ◽  
Eddy Current Losses ◽  
Switched Reluctance ◽  
Element Simulation ◽  
Core Losses

The direct coil cooling method is one of the existing cooling techniques for electric machines with concentrated windings, in which cooling tubes of conductive material are inserted between the windings. In such cases, eddy current losses are induced in those cooling tubes because of the time variant magnetic field. To compute the cooling tubes losses, either a transient finite element simulation (mostly based on commercial software), or a full analytical method, which is more complex to be constructed, is required. Instead, this paper proposes a simple and an accurate combined semi-analytical-finite element method to calculate the losses of electric machines having cooling tubes. The 2D magnetostatic solution of the magnetic field is obtained e.g., using the free package “FEMM”. Then, the eddy current losses in the tubes are computed using simple analytical equations. In addition, the iron core losses could be obtained. In order to validate the proposed method, two cases are investigated. In Case 1, a six-toothed stator of a switched reluctance machine (SRM), without rotor, is employed in which six cooling tubes are used while in Case 2 a complete rotating SRM is studied. The proposed method is validated by a 2D transient simulation in the commercial software “ANSYS Maxwell” and also by experimental measurements. Evidently, the proposed method is simple and fast to be constructed and it is almost free of cost.

An Analytical Method to Calculate the Eddy Current Losses of Transformer Shielding Coil

2012 ◽  
Vol 229-231 ◽  
pp. 884-887
Author(s):  
Bao Dong Bai ◽  
Ying Ying Gao ◽  
Jia Yin Wang
Keyword(s):  
Magnetic Field ◽  
Finite Element Method ◽  
Finite Element ◽  
Eddy Current ◽  
Analytical Method ◽  
Analytical Formula ◽  
The Finite Element Method ◽  
Eddy Current Losses ◽  
Leakage Magnetic Field ◽  
Current Equation

This paper mainly researches the eddy current losses of transformer shielding coil by adopting for analytical method. This method calculates the conductor’s boundary conditions directly by using the analytical solution of the leakage magnetic field, which is generated into the conductor eddy current equation for the analytical formula, then compared the analytical method with the finite element method to fix the analytical formula, the relevant theories are applied to analyze the results of using two different shielding to reduce the losses and find the effectively measures.

scholarly journals Finite Element Solutions for Magnetic Field Problems in Terfenol-D Transducers

Sensors ◽  
2020 ◽  
Vol 20 (10) ◽  
pp. 2808
Author(s):  
Duo Teng ◽  
Yatian Li
Keyword(s):  
Magnetic Field ◽  
Finite Element ◽  
Eddy Current ◽  
Permanent Magnets ◽  
Eddy Currents ◽  
Iron Alloy ◽  
Current Response ◽  
Bias Magnetic Field ◽  
Field Range ◽  
Eddy Current Losses

An appropriate magnetic design helps ensure that the Terfenol-D (Terbium- Dysprosium-Iron alloy) rods in giant magnetostrictive transducers have the perfect magnetostriction ability. To determine the optimum Terfenol-D rod state, a segmented stack configuration comprised by the Terfenol-D rods and NdFeB (neodymium-iron-boron) permanent magnets is presented. The bias magnetic field distributions simulated through the finite element method indicate that the segmented stack configuration is one effective way to produce the desired bias magnetic field. Particularly for long stacks, establishing a majority of domain to satisfy the desired bias magnetic field range is feasible. On the other hand, the eddy current losses of Terfenol-D rods are also the crucial to their magnetostriction ability. To reduce eddy current losses, the configuration with digital slots in the Terfenol-D rods is presented. The induced eddy currents and the losses are estimated. The simulations reveal that the digital slots configuration decreases the eddy current losses by 78.5% compared to the same size Terfenol-D rod with only a hole. A Terfenol-D transducer prototype has been manufactured using a Terfenol-D rod with a mechanical prestress of about 10 MPa and a bias magnetic field of about 42 kA/m. Its maximum transmitting current response of 185.4 dB at 3.75 kHz indicates its practicability for application as an underwater projector.

scholarly journals Performance Analysis of High-Speed Electric Machines Supplied by PWM Inverters Based on the Harmonic Modeling Method

Energies ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2606
Author(s):  
Marko Merdžan
Keyword(s):  
Finite Element ◽  
Performance Analysis ◽  
Permanent Magnet ◽  
Eddy Current ◽  
Pulse Width ◽  
High Speed ◽  
Electric Machines ◽  
Switching Frequency ◽  
Eddy Current Losses ◽  
Pulse Width Modulated

This paper presents a method for the performance analysis of high-speed electric machines supplied with pulse-width modulated voltage source inverters by utilizing a fast analytical model. By applying a strict mathematical procedure, effective expressions for the calculation of rotor eddy current losses and electromagnetic torque are derived. Results obtained by the approach suggested in this study are verified by the finite element model, and it is shown that the proposed method is superior in comparison to the finite element method in terms of computation time. The proposed method enables fast parameter variation analysis, which is demonstrated by changing the inverter switching frequency and electric conductivity of the rotor and analyzing the effects of these changes on rotor eddy current losses. The presented work separately models effects of the permanent magnet and pulse-width modulated stator currents, making it suitable for the analysis of both high-speed permanent magnet machines and high-speed induction machines.

Modeling of eddy current losses in the iron core of electrical machines by a finite element homogenization method

2018 ◽  
Vol 12 (133) ◽  
pp. 24
Author(s):  
Vương Đặng Quốc
Keyword(s):  
Finite Element ◽  
Eddy Current ◽  
Eddy Currents ◽  
Source Region ◽  
Homogenization Method ◽  
Magnetic Flux Density ◽  
Iron Core ◽  
Eddy Current Losses ◽  
Density Distributions ◽  
High Frequency Effects

A finite element homogenization method is proposed for the magetodynamic h-conform finite element forumulation to compute eddy current losses in electrical steel laminations. The lamination stack is served as a source region carrying predefined current density and magnetic flux density distributions presenting the eddy current losses and skin effects in each lamination. In order to solve this problem, the stacked laminations are converted into continuums with which terms are associated for considering the eddy current loops produced by both parallel and perpendicular fluxes. An accurate model of accuracy is developed via an accurate analytical expression of the eddy currents and makes the method adapted to both low and high frequency effects to capture skin depths of fields along thicknesses of the laminations.

scholarly journals Direct Consideration of Eddy Current Losses in Laminated Magnetic Cores in Finite Element Method (FEM) Calculations Using the Laplace Transform

Energies ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1174
Author(s):  
Marek Gołębiowski ◽  
Lesław Gołębiowski ◽  
Andrzej Smoleń ◽  
Damian Mazur
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Laplace Transform ◽  
Eddy Current ◽  
Electric Machines ◽  
The Finite Element Method ◽  
Eddy Current Losses ◽  
Simulation Process ◽  
The Laplace Transform ◽  
Element Method

The following article presents a computation procedure that enables us to simulate the dynamic states of electric machines with a laminated magnetic core, with direct consideration of the eddy current losses. The presented approach enables a significant reduction of the simulation process computational complexity. The verification of the obtained data correctness is based on a detailed balance of energy and power in the investigated system. The correctness of the obtained results was also confirmed by comparing them with the results included in norms that describe the losses in laminated sheets. The presented approach is based on expressing the equivalent permeability of transformer metal sheets by using RC or RL circuits. The impedances of these circuits are treated as the transmittance of Infinite Impulse Response filters (IIR) of the Laplace s variable. In this form they are implemented in direct calculations of the dynamics of electric machines based on field-circuital models, using the Finite Element Method (FEM). In this way, we present the method of including eddy current losses in laminated metal circuits of chokes or transformers, during calculations using the finite element method, with the IIR filter in the domain of the variable s of the Laplace transform. Eddy current losses are directly included in the calculation process. Therefore, they have a direct impact on the transient state waveforms. However, the use of the Laplace variable s caused an excessive increase in the number of state variables, and the overall computational efficiency of the presented method is sufficiently low so as to be used in the simulation process of electrical machine dynamic states with a relatively large number of elements in the FE Model.

Rotor Eddy Current Losses Analysis on BPMSM Using FEM

2012 ◽  
Vol 150 ◽  
pp. 85-89
Author(s):  
Tao Zhang ◽  
Huang Qiu Zhu
Keyword(s):  
Magnetic Field ◽  
Finite Element Method ◽  
Finite Element ◽  
Permanent Magnet ◽  
Relative Motion ◽  
Eddy Current ◽  
High Speed ◽  
Necessary Conditions ◽  
Eddy Current Losses ◽  
Research Results

It is important to clarify the rotor eddy current losses in bearingless permanent magnet synchronous (BPMSM) for temperature rising to induce irreversible demagnetization. In this paper, the torque and radial suspension force producing mechanisms of BPMSM are introduced. The relative motion relationships among radial suspension force, rotor magnetic field and suspension winding magnetic field are analyzed. The necessary conditions of producing stable controllable radial suspension force in single direction are concluded. The rotor eddy current losses in BPMSM with PB=PM+1 and PB=PM-1 are calculated and compared using 2D time-steeping finite element method. The research results have shown that the BPMSM with PB=PM+1 is the most suitable for high speed operation with the minimum eddy current losses in rotor.

Determination of eddy current losses and hysteresis losses in magnetic circuits of electrical machines

2020 ◽  
pp. 54-58
Author(s):  
S. M. Plotnikov
Keyword(s):  
Eddy Current ◽  
Magnetization Reversal ◽  
Eddy Currents ◽  
Technical Problem ◽  
Electrical Machines ◽  
Eddy Current Losses ◽  
Hysteresis Losses ◽  
Magnetic Circuits ◽  
Core Losses ◽  
Reversal Frequency

The division of the total core losses in the electrical steel of the magnetic circuit into two components – losses dueto hysteresis and eddy currents – is a serious technical problem, the solution of which will effectively design and construct electrical machines with magnetic circuits having low magnetic losses. In this regard, an important parameter is the exponent α, with which the frequency of magnetization reversal is included in the total losses in steel. Theoretically, this indicator can take values from 1 to 2. Most authors take α equal to 1.3, which corresponds to the special case when the eddy current losses are three times higher than the hysteresis losses. In fact, for modern electrical steels, the opposite is true. To refine the index α, an attempt was made to separate the total core losses on the basis that the hysteresis component is proportional to the first degree of the magnetization reversal frequency, and the eddy current component is proportional to the second degree. In the article, the calculation formulas of these components are obtained, containing the values of the total losses measured in idling experiments at two different frequencies, and the ratio of these frequencies. It is shown that the rational frequency ratio is within 1.2. Presented the graphs and expressions to determine the exponent α depending on the measured no-load losses and the frequency of magnetization reversal.

Simulation research on low frequency sound absorption of monostable metamaterials

2021 ◽  
Vol 263 (6) ◽  
pp. 648-652
Author(s):  
Tuo Xing ◽  
Xianhui Li ◽  
Xiaoling Gai ◽  
Zenong Cai ◽  
Xiwen Guan
Keyword(s):  
Magnetic Field ◽  
Finite Element ◽  
Theoretical Model ◽  
Finite Element Simulation ◽  
Sound Absorption ◽  
Magnetic Force ◽  
Low Frequency ◽  
Low Frequencies ◽  
Element Simulation ◽  
Simulation Results

The monostable acoustic metamaterial is realized by placing a flexible panel with a magnetic proof mass in a symmetric magnetic field. The theoretical model of monostable metamaterials has been proposed. The method of finite element simulation is used to verify the theoretical model. The magnetic force of the symmetrical magnetic field is simplified as the relationship between force and displacement, acting on the mass. The simulation results show that as the external magnetic force increases, the peak sound absorption shifts to low frequencies. The theoretical and finite element simulation results are in good agreement.

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