Comparison between models for eddy-current loss calculations in rotor surface-mounted permanent magnets

Alexandrova, J.; Jussila, H.; Nerg, Janne; Pyrhönen, Juha

doi:10.1109/icelmach.2010.5608247

Cited by 17 publications

(6 citation statements)

References 8 publications

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“…In this paper, it uses ANSYS software to conduct 3D dynamic finite element modeling for adjustable permanent magnetic coupler with slotted structure and it analyzes the relevant magnetic field amount. [12][13][14][15] the permanent magnet selects NdFeB with specification of N38H; copper disc uses brass with model number at H62 and steel disc uses No.45 steel. As to structure dimension, in addition to using 2D simulation parameters, the other relevant parameters are as follows: copper disc internal radius -90mm, external radium 140 mm; steel disc internal radius -90mm, external radium 140 mm; amount of permanent magnet -18; number of ladder-shaped slots -72; motor output rotation speed --1455r/min; 3D dynamic simulation model for slotted structure and plain structure is as illustrated in Figure 4: Figure 5 (a) describes eddy current distribution of slotted copper disc.…”

Section: Modelingmentioning

confidence: 99%

Characteristic Analysis of Adjustable Permanent Magnetic Coupler with Slotted Conductor Disk

Gao¹,

Wang²,

Lin³

2015

IJSH

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It is essential to optimize the conductor surface vortex path because the efficiency of Permanent magnet governor depends on the excitation level of the induced current. In order to further improve efficiency, this article focuses on a permanent magnet governor with slotted conductor disk. The 2D and 3D dynamic simulation model are established and the characteristics of slotted and plain structure are analyzed. The results are shown that the vortex path of the permanent magnet governor with slotted structure is optimized, the magnetic flux leakage is reduced, and the thermal capacity is higher. The transmission torque mathematical model with temperature parameters is established considering the transmission torque. The transmission torque is affected by conductivity changing with the conductor disk heating. The effects of temperature changing and relative speed on torque transmission are analyzed. Finally, the torque characteristics of slotted and plain structure were compared by the experimental test under different conditions. It is proved that the slotted structure can improve the transmission efficiency and reduce the vortex field impact due to the temperature of conductor disk rising. And it is verified that the mathematical model is valid.

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Section: Modelingmentioning

confidence: 99%

Characteristic Analysis of Adjustable Permanent Magnetic Coupler with Slotted Conductor Disk

Gao¹,

Wang²,

Lin³

2015

IJSH

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“…Therefore, several empirical calculation methods are developed and compared in [28] and [29]. However, we implemented the numerical method of Ede [9], which couples a 2D FEM and a 3D FEM: from the static 2D FEM of the complete machine, which is run for several rotor positions, the magnetic flux density vector is recorded in a grid of points in the magnet, as a function of time (or rotor position).…”

Section: E Magnet Loss Caused By Space Harmonicsmentioning

confidence: 99%

Influence of the Amount of Permanent-Magnet Material in Fractional-Slot Permanent-Magnet Synchronous Machines

Sergeant

Bossche

2014

IEEE Trans. Ind. Electron.

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Abstract-The efficiency of permanent magnet synchronous machines (PMSM) with outer rotor and concentrated windings is investigated as a function of the mass of magnets used, keeping the power, volume and mechanical air gap thickness constant. In order to be useful for electric vehicle motors and wind turbine generators, the efficiency is computed in a wide speed and torque range, including overload. For a given type and amount of magnets, the geometry of the machine and the efficiency map are computed by analytical models and finite element models, taken into account iron loss, copper loss, magnet loss and pulse width modulation loss. The models are validated by experiments. Furthermore, the demagnetization risk and torque ripple are studied as a function of the mass of magnets in the machine. The effect of the mass of magnets is investigated for several soft magnetic materials, several combinations of number of poles and number of stator slots, and for both rare earth (NdFeB) magnets and ferrite magnets. It is observed that the amount of permanent magnet material can vary in a wide range with a minor influence on the efficiency, torque density, and torque ripple and with a limited demagnetization risk. A lot of papers deal with rotor losses in the considered type of machines, and give methods to compute them. For example [6] gives a general method for several slot/pole configurations. Polinder [7] studies losses in the solid back iron of PMSM with fractional slot windings. Atallah presented an analytical model to compute magnet loss [8], and Ede proposed a computationally efficient 3D numerical method to compute the magnet loss [9]. IndexAn aspect of fractional-slot concentrated-winding PMSM's that is less investigated, is how much the amount of magnets can be reduced, and how this affects the global machine design and performance. As the price of rare earth magnets is high, PMSM's with small amount of magnets become interesting, on condition that their efficiency and torque density remain high. It is known that very powerful and light permanent magnet machines can be made when a lot of PM material can be used: for example the slotless brushless DC PMSM of [10] has two concentric rotors, both of them completely covered with a thick layer of NdFeB magnets in Halbach array. Alternatives are investigated to reduce the required amount of permanent magnets, or even to have motors without magnets [11]. Nevertheless, [12] compared caged induction, reluctance, and PM motor technologies for the more electric aircraft, concluding that three-phase permanent magnet machines may still be the favorite choice.Therefore, we investigate the impact of the amount of magnets and the magnetic material grade in the stator of the PMSM on the efficiency, keeping the machine volume and torque density constant. Here, we consider not only the efficiency at nominal speed N nom and torque T nom , but also the average efficiency in the speed range 0.25-1.50×N nom and torque range 0.25-1.50×T nom . A number of effects of reducing the amount ...

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“…The difference between many techniques was investigated in this review article [4]. In this review paper, the eddy losses were subdivided into two main sources.…”

Section: Introductionmentioning

confidence: 99%

“…[7] introduced simple mathematical formulations for eddy-current loss calculations due to the time harmonics in the stator current which neglected the spatial distribution of this field on the surface of the PM and also neglected the slotting and skin effect. The comparison in [4] showed that the computation of the eddy-current loss due to slotting introduced in [8] should be more investigated for more precise results.…”

Section: Introductionmentioning

confidence: 99%

Comparison of Methods for Permanent Magnet Eddy-Current Loss Computations With and Without Reaction Field Considerations in Axial Flux PMSM

2015

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This paper presents an analytical solution of the eddy currents in the permanent magnets (PMs) in the Axial Flux Permanent Magnet Synchronous Machine (AFPMSM) using a coupled solution of Maxwell's equations and electric circuit network. This is based on calculating the axial field in an accurate way on the surface of the PM. This method is able to take into account the effect of armature field and slots. The eddy currents are obtained by imposing this solution on the PM which is modeled by a simple electric network. This network is composed of simple resistances and inductances. The inductances are used to model the reaction field effect of the eddy currents flowing through the PM and also the skin effect. To show this effect, the machine is excited with different sources at different speeds. Also, a variant of the model is made that neglects the inductances, in order to show in which conditions this "low-frequency approximation" is acceptable. It is concluded from this paper that inclusion of the reaction field is necessary when the machine is excited by a pulse width modulated (PWM) current, while for a sinusoidal excitation, the reaction field effect has minor contributions to the total eddy losses. In addition, the reaction field has major influence at higher speeds rather than lower speeds for PWM injection. In conclusions, for a preliminary design, the resistance model without the reaction field computation would be enough for the calculation of the PM losses. The circuit model is also capable of obtaining the solution with PM segmentation. In this paper different PM segments were studied from the circuit model and FE model point of view. Compared to the Finite Element (FE) Model, the circuit model has the advantage of flexibility in geometrical machine parameters, less CPU time, and accurate results for the PM losses up to 10%.

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Comparison between models for eddy-current loss calculations in rotor surface-mounted permanent magnets

Cited by 17 publications

References 8 publications

Characteristic Analysis of Adjustable Permanent Magnetic Coupler with Slotted Conductor Disk

Characteristic Analysis of Adjustable Permanent Magnetic Coupler with Slotted Conductor Disk

Influence of the Amount of Permanent-Magnet Material in Fractional-Slot Permanent-Magnet Synchronous Machines

Comparison of Methods for Permanent Magnet Eddy-Current Loss Computations With and Without Reaction Field Considerations in Axial Flux PMSM

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