Improvement in Torque Density by Ferrofluid Injection into Magnet Tolerance of Interior Permanent Magnet Synchronous Motor

Yang, In-Jun; Song, Si-Woo; Kim, Dongho; Kim, Kwangsoo; Kim, Won‐Ho

doi:10.3390/en14061736

Cited by 4 publications

(4 citation statements)

References 29 publications

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“…In addition, since the motor to which ferrofluid is applied has been sufficiently verified, the reliability of the simulation data in this paper is high enough [28]. Consequently, the torque of the model increased by 3.9% and the eddy current loss decreased by 40%.…”

Section: Discussionmentioning

confidence: 91%

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A study on reducing eddy current loss of sleeve and improving torque density using ferrofluid of a surface permanent magnet synchronous motor

Song¹,

Jeong

Kim

et al. 2021

IET Electric Power Appl

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It has advantages such as high power density and miniaturisation when the motor operates at high speed. However, as a side effect, the loss density is much higher than that of a constant speed motor. In addition, a retaining sleeve is inserted in the high‐speed motors to prevent the rotor from scattering. This insertion deteriorates the performance due to the increase of airgap, and eddy current loss occurs in the sleeve. In order to improve these shortcomings, the sleeve is redesigned in this paper. A groove was dug into the retaining sleeve and ferrofluid was injected. Ferrofluid refers to water or oil mixed with ultra‐fine powder. Since the permeability of ferrofluid is greater than that of airgap, it is possible to have high output and high efficiency. Since the material of the sleeve is non‐permeable, the performance is reduced with the same effect as increasing the airgap. However, if a ferrofluid is inserted by digging a groove in the retaining sleeve, the magnetic flux from the magnet flows into the stator through the ferrofluid, which has the same effect as reducing the airgap. Therefore, the torque density increases. Also, the eddy current loss is reduced through the retained sleeve groove. Moreover, a sleeve skew structure was used to further reduce the eddy current loss. In this paper, the mechanical rigidity at the rated speed was also taken into consideration. As a result, eddy current loss was reduced and torque density was improved. This is verified through the final finite element analysis.

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Section: Discussionmentioning

confidence: 91%

“…The magnetic fluid image observed with transmission electron microscopy (TEM) is shown in Figure 1a. Ferrofluid does not have magnetism when there is no magnetic field, but it becomes magnetised when an external magnetic field is applied with a magnet [23][24][25][26]. Materials with this property are called supermagnetic.…”

mentioning

confidence: 99%

A study on reducing eddy current loss of sleeve and improving torque density using ferrofluid of a surface permanent magnet synchronous motor

Song¹,

Jeong

Kim

et al. 2021

IET Electric Power Appl

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“…In the application of electrical machines, ferrofluids are used for air-gap elimination, reluctance reduction [28][29][30] and eddy current elimination [31] to achieve better performance. In addition, ferrofluids can be simultaneously used for cooling applications in electric machines.…”

Section: Introductionmentioning

confidence: 99%

Ferrofluid‐based electrical machines: Conceptualization and experimental evaluation

Darabi,

Pourmirzaei Deylami,

Sheikhian

et al. 2024

The Journal of Engineering

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This article intends to propose a new concept of electric machines that works based on a category of magnetic fluids called “ferrofluids”. For this purpose, a disc‐shaped rotor filled with ferrofluid material is employed instead of a common rotor of an axial‐flux machine, and the conceptual design of the new machine named here “axial‐flux ferrofluid electric machine (FFEM)” is presented. The operation principle of the FFEM is described and a dynamic‐transient model built on the d–q axes equivalent circuits is presented. Simulations are carried out by applying the given model in MATLAB and the results are investigated in different operating conditions. In order to identify the basic parameters and validate the simulation results, a prototype of the FFEM has been designed and manufactured, and some preliminary functional tests have been performed on the prototype. All simulation and experimental results indicate some distinguished excellent performances of the new machine. In the end, it can be stated briefly with some confidence that ferrofluid electric machines can have a high potential for future research and applications in various industries due to the simplicity of the structure, self‐starting capability, ability to work at a wide range of speeds and a flat torque profile.

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“…If the magnetic fluid is filled in an appropriate space, the magnetic field is more concentrated there. Several researchers are using this phenomenon to improve the efficiency and torque of various rotating machines, for example, induction machines [11,12], a linear motor [13], and an interior permanent magnet synchronous motor [14].…”

Section: Introductionmentioning

confidence: 99%

Torque Analysis for Rotational Devices with Nonmagnetic Rotor Driven by Magnetic Fluid Filled in Air Gap

Kim¹,

Choi²

2021

Energies

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In magnetomechanical applications, it is necessary to calculate the magnetic force or torque of specific objects. If the magnetic fluid is involved, the force and torque also include the effect of pressure caused by the fluid. The standard method is to solve the Navier–Stokes equation. However, obtaining magnetic body force density is still under controversy. To resolve this problem, this paper shows that the calculation of the torque of these applications should not only use the magnetic force calculation method, but also consider the mechanical pressure using an indirect approach, such as the virtual work principle. To illustrate this, we use an experimental motor made of a nonmagnetic rotor immersed in a magnetic fluid. Then, we show that the virtual work principle in appropriate approach can calculate the output torque of the nonmagnetic rotor due to pressure of the magnetic fluid. Numerical analysis and experimental results show the validity of this approach. In addition, we also explain how the magnetic fluid transmits its magnetic force to the stator and rotor, respectively.

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Improvement in Torque Density by Ferrofluid Injection into Magnet Tolerance of Interior Permanent Magnet Synchronous Motor

Cited by 4 publications

References 29 publications

A study on reducing eddy current loss of sleeve and improving torque density using ferrofluid of a surface permanent magnet synchronous motor

A study on reducing eddy current loss of sleeve and improving torque density using ferrofluid of a surface permanent magnet synchronous motor

Ferrofluid‐based electrical machines: Conceptualization and experimental evaluation

Torque Analysis for Rotational Devices with Nonmagnetic Rotor Driven by Magnetic Fluid Filled in Air Gap

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