An Improved Subdomain Model for Predicting Magnetic Field of Surface-Mounted Permanent Magnet Machines Accounting for Tooth-Tips

Wu, Lijian; Zhu, Z. Q.; Staton, D.A.; Popescu, Mircea; Hawkins, D.

doi:10.1109/tmag.2011.2116031

Cited by 203 publications

(117 citation statements)

References 36 publications

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“…1, [15] with simplified slots and uniform distribution of current in them is presented assuming infinitely permeable iron materials and replicates the flux density variations in the magnet quiet accurately. Since circumferential component of flux density is relatively small, its effect on eddy current loss is negligible [20].…”

Section: Sub Domain Model and Calculation Of Magnet Flux Density mentioning

confidence: 99%

“…The eddy current loss due to radial component of magnetic field is considered in this paper. The radial component of the flux density at a radius 'r' along the magnet [15], which contributes to the magnet loss can be represented as,In the rotor reference Substituting (2) and (3) into (1), and rearranging, the radial component of the flux density at a radius 'r' along the magnet which contributes to the magnet loss can be expressed in the rotor reference as The coefficients which accounts for the slotting effect, namely, where =1, 3, 5,…and l M is the magnet axial length. This expression ensures that the z-component of the eddy current density is zero at both axial ends of the magnet.…”

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confidence: 99%

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Analytical Prediction of 3-D Magnet Eddy Current Losses in Surface Mounted PM Machines Accounting Slotting Effect

Nair

Wang

Chin

et al. 2017

IEEE Trans. Energy Convers.

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Abstract-This paper presents a novel analytical technique for predicting 3-dimensional (3D) magnet eddy current losses accounting the slotting effect of any pole-slot combinations for a surface mounted permanent magnet machine under any conditions of load. The slotting effect is incorporated from a subdomain model and the 3D boundary conditions are imposed with the current vector potential to represent the 3D eddy currents circulating in the magnets. The proposed model in polar coordinate system is demonstrated on a fractional slot rare-earth permanent magnet machine by analyzing its magnet losses as functions of axial and circumferential segmentations. The results have shown an excellent match with 3D numerical calculations. The analytical prediction has also been validated by experimental tests. The interaction of the armature reaction field with the slotting harmonics is analyzed and their effect on eddy current loss in rotor magnets is established. The proposed technique is employed to evaluate the effect of slotting on magnet loss with increase in field weakening angle.Index Terms-Current vector potential, eddy currents, finite element, subdomain model, permanent magnet, 3D analytical. I. INTRODUCTIONhe rotor magnets of permanent magnet (PM) machines used in high speed and power density applications are exposed in increased rate of alternating magnetic field and incur eddy current loss. Eddy currents are more pronounced in magnets especially at higher speeds for such machines with modular or concentrated winding configurations [1,2], as their stator magneto-motive force (mmf) contains a large number of space harmonics which rotate at different speeds along the rotor. Accurate prediction of magnet losses at the design stage, not only gives better efficiency evaluation, but also may prevent its excessive temperature rise and hence reduce the risk of partial demagnetization.In order to evaluate the eddy current losses in permanent magnets, variety of methods have been reported in a large number in literatures. In general, evaluation of rotor eddy current losses requires simultaneous solutions for the governing equations of the magnetic and eddy current fields.The computationally efficient 2D numerical methods such as transient finite element analysis (FEA) to calculate the eddy current losses [3], [4] can yield good results but lacks any physical insight on the mechanism of eddy current loss. Hence a few 2D analytical methods are developed to predict the magnet eddy current loss with varying degree of accuracy [5][6][7][8][9]. These methods often neglect the slotting effect and approximate winding currents by an equivalent current sheet distributed over the stator bore radius.Unless the slotting harmonics are considered in the loss evaluation, the no load magnetic loss and also its interaction with the armature filed harmonics at diverse load conditions cannot be quantified. As the eddy current density inside the magnets is dependent on the time derivative of the magnetic vector potential within it, a sufficie...

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Section: Sub Domain Model and Calculation Of Magnet Flux Density mentioning

confidence: 99%

mentioning

confidence: 99%

Analytical Prediction of 3-D Magnet Eddy Current Losses in Surface Mounted PM Machines Accounting Slotting Effect

Nair

Wang

Chin

et al. 2017

IEEE Trans. Energy Convers.

View full text Add to dashboard Cite

show abstract

“…Thus, in the world scientific and technical literature, much attention has been paid to the development of theoretical and metho do lo gi cal approaches to solving the problems arising when de veloping mathematical models of elec tric objects. In these approaches, efforts are made to take the construction of objects into account to as great an extent as possible and apply real physical laws of electromagnetic phe nomena occurring in the device media [1][2][3][4][5][6][7][8][9][10][11][12]. One of the more advanced strategies for successfully tackling this problem is to develop mathematical models of electric objects exclusively based on the theory of electromagnetic fields.…”

Section: Introductionmentioning

confidence: 99%

An analysis of electromagnetic processes in a turbogenerator with a real rotor and a stator tooth structure in the no-load mode

Kovivchak

2017

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An analysis of electromagnetic processes in a turbogenerator with a real rotor and a stator tooth structure in the no-load mode Analiza procesów electromagnetychnych w turbogeneratorze ze structurami realnymi rotora i statora na biegu jałowym AbstractThe results of the research presented in this article are 2-D mathematical field models of a turbogenerator in the no-load mode with real tooth structures on the rotor and stator in the rotor coordinate system and in the physical systems of reference. The results of the computer simulation of the electromagnetic field in the cross-sectional zones of the device in the no-load mode transition process are pre¬sented.

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“…Some mistakes were clarified at the same time. Wu [15] developed an improved analytical subdomain model for calculating the open-circuit magnetic field in surface-mounted permanent magnet machines accounting for the tooth-tips in the slots based on 2-D polar coordinate.…”

Section: Introductionmentioning

confidence: 99%

Improved Method for Calculating Magnetic Field of Surface-Mounted Permanent Magnet Machines Accounting for Slots and Eccentric Magnet Pole

Zhou¹,

Li²,

Wang³

et al. 2015

Journal of Electrical Engineering and Technology

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-This paper presented an improved analytical method for calculating the open-circuit magnetic field in the surface-mounted permanent magnet machines accounting for slots and eccentric magnet pole. Magnetic field produced by radial and parallel permanent magnet is equivalent to that produced by surface current according to equivalent surface-current method of permanent magnet. The model is divided into two types of subdomains. The field solution of each subdomain is obtained by applying the interface and boundary conditions. The magnet field produced by equivalent surface current is superposed according to superposition principle of vector potential. The investigation shows harmonic contents of radial flux density can be reduced a lot by changing eccentric distance of eccentric magnet poles compared with conventional surface-mounted permanent-magnet machines with concentric magnet poles. The FE(finite element) results confirm the validity of the analytical results with the proposed model.

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An Improved Subdomain Model for Predicting Magnetic Field of Surface-Mounted Permanent Magnet Machines Accounting for Tooth-Tips

Cited by 203 publications

References 36 publications

Analytical Prediction of 3-D Magnet Eddy Current Losses in Surface Mounted PM Machines Accounting Slotting Effect

Analytical Prediction of 3-D Magnet Eddy Current Losses in Surface Mounted PM Machines Accounting Slotting Effect

An analysis of electromagnetic processes in a turbogenerator with a real rotor and a stator tooth structure in the no-load mode

Improved Method for Calculating Magnetic Field of Surface-Mounted Permanent Magnet Machines Accounting for Slots and Eccentric Magnet Pole

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