Characterization and Experimental Verification of the Axial Unbalanced Magnetic Force in Brushless DC Motors

Kim, J. Y.; Sung, S. J.; Jang, Gunhee

doi:10.1109/tmag.2012.2203113

Cited by 25 publications

(7 citation statements)

References 6 publications

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“…Zarko et al [132] carried out the measurement and analysis of bearing and shaft vibrations with no-load and loaded conditions. Kim et al [175] developed an experimental device to measure the axial UMF and verify the simulated results in brushless DC motors. The experimental setup is illustrated in Figure 13 as follows: The direct experiment method was studied by Lee et al [176].…”

Section: Experimental Studymentioning

confidence: 99%

Review of Electromagnetic Vibration in Electrical Machines

Han

Chu

2018

Energies

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Electrical machines are important devices that convert electric energy into mechanical work and are widely used in industry and people's life. Undesired vibrations are harmful to their safe operation. Reviews from the viewpoint of fault diagnosis have been conducted, while summaries from the perspective of dynamics is rare. This review provides systematic research outlines of this field, which can help a majority of scholars grasp the ongoing progress and conduct further investigations. This review mainly generalizes publications in the past decades about the dynamics and vibration of electrical machines. First the sources of electromagnetic vibration in electrical machines are presented, which include mechanical and electromagnetic factors. Different types of air gap eccentricity are introduced and modeled. The analytical methods and numerical methods for calculating the electromagnetic force are summarized and explained in detail. The exact subdomain analysis, magnetic equivalent circuit, Maxwell stress tensor, winding function approach, conformal mapping method, virtual work principle and finite element analysis are presented. The effects of magnetic saturation, slot and pole combination and load are discussed. Then typical characteristics of electromagnetic vibration are illustrated. Finally, the experimental studies are summarized and the authors give their thoughts about the research trends.Energies 2018, 11, 1779 2 of 33 vibration mechanism can be helpful for the design of electrical machines. Therefore, the study of the electromagnetic vibration of electrical machines has practical significance.Electromagnetic vibrations are usually generated by the distorted air-gap field of an eccentric rotor in electrical machines. The uneven air-gap is directly related to the eccentricity, which is common in rotating electrical machines. Eccentricity can be caused by several reasons, such as relative misalignment of the rotor and stator in the fixing stage, misalignment of the load axis and rotor shaft, elliptical stator inner cross section, wrong placement or rubbing of ball bearings, mechanical resonance, and unbalanced loads [1,2]. Eccentricities can be further subdivided into two categories: circumferential unequal air gaps and axial unequal air gaps. The former can be grouped into static eccentricity and dynamic eccentricity. In the case of static eccentricity, the rotor rotates around its own geometric axis, which is not the geometric axis of the stator. In the case of dynamic eccentricity, the rotor is not concentric and rotates around the geometric axis of the stator. In reality, both static eccentricity and dynamic eccentricity tend to coexist. An inherent static eccentricity exists, even in newly manufactured machines, due to the build-up of tolerances during the manufacturing and assembly procedure, as has been reported in [3]. Unequal air gaps cause unbalanced magnetic forces (UMFs) [4] on the rotor, which lead to mechanical stress on some part of the shaft and bearing. After prolonged operation, these fac...

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Section: Experimental Studymentioning

confidence: 99%

Review of Electromagnetic Vibration in Electrical Machines

Han

Chu

2018

Energies

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“…In this paper, the change of the torque and axial magnetic force of the rotor during axial movement is qualitatively analyzed by the virtual displacement method [20,21], and the exact calculation is solved by numerical method. Ignoring the magnetic saturation, it is believed that the magnetic energy stored in the permanent magnet is unchanged before and after the rotor displacement, the magnetic energy in the air gap can be expressed as follows:…”

Section: B Analysis Of the Axial Magnetic Force And Torque Charactermentioning

confidence: 99%

Magnetic field and operating performance analysis of conical-rotor permanent magnet synchronous motor

Wang

Huang

Feng

2018

Trans. Electr. Mach. Syst.

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In order to accurately analyze the magnetic field of conical-rotor permanent magnet synchronous motor (CR-PMSM), the effectiveness of two methods was studied on handling of problems concerned with non-uniform distribution of magnetic field along axial direction in CR-PMSM, which were sectional calculation (SC) method and three-dimensional finite element (3-D FE) method. On this basis, the influence of the axial displacement and dq-axis currents on the operating characteristics of axial magnetic force and torque is analyzed by using the 3-D FE model. Analysis results show that the axial magnetic force and torque decrease with the increase of axial displacement of the rotor, and the amplitude regularity of the axial magnetic force is affected by the d-axis current. A prototype machine is fabricated and tested, in order to validate the design theory. Index Terms-Magnetic field of conical-rotor permanent magnet synchronous motor, operating characteristics, non-uniform of magnetic field, 3-D FE method.

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“…In this paper, for the sake of convenience, the ventilating ducts are not taken into account due to their small effect. Changing the units into SI system, (5) can be transformed to The development of expressions for / for the ends and the contribution of the ends to 0 / can be calculated by (7) and finally displayed as Figure 4:…”

Section: Ump Analysis Via Conducting Paper Modelmentioning

confidence: 99%

“…By far, the air-gap eccentricity is primarily focused on the radial one [1][2][3][4][5], while actually there is also axial airgap eccentricity (AAGE) existing. AAGE can be caused, for example, by the axial displacement of the rotor, frequently occurring in the hydrogenerators [6][7][8] and also happening in the turbogenerators from time to time.…”

Section: Introductionmentioning

confidence: 99%

Analysis and Simulation on UMP and EMT Characters of Turbogenerator under Axial Air-Gap Eccentricity

He¹,

Deng²,

Tang³

2015

International Journal of Rotating Machinery

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The purpose of this paper is to investigate the effect of the axial air-gap eccentricity (AAGE) on the electromagnetic characters such as the axial unbalanced magnetic pull (UMP) and the electromagnetic torque (EMT). Firstly, the theoretical model of AAGE is set up, and the formulas of the axial UMP and EMT are deduced. Then the simulation study of a SDF-9 nonsalient pole synchronous generator is taken with Ansoft Maxwell to calculate the detailed axial UMPs and EMTs under normal condition and five AAGE conditions, respectively, with 2 mm to 10 mm rotor displacements. It is shown that an apparent axial UMP will be produced due to AAGE, while EMT and the phase current will be decreased. In addition, the magnetic flux density (MFD) on the stator end and the rotor end, which are more far from the center position of the stator core in the axial direction, will be decreased, while the MFD on the other ends will be generally kept stable. As AAGE develops, the axial UMP will be increased, while EMT and the phase current will be decreased. The proposed work offers a reference for the fault diagnosis and monitoring on AAGE.

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Characterization and Experimental Verification of the Axial Unbalanced Magnetic Force in Brushless DC Motors

Cited by 25 publications

References 6 publications

Review of Electromagnetic Vibration in Electrical Machines

Review of Electromagnetic Vibration in Electrical Machines

Magnetic field and operating performance analysis of conical-rotor permanent magnet synchronous motor

Analysis and Simulation on UMP and EMT Characters of Turbogenerator under Axial Air-Gap Eccentricity

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