Cogging Torque and Unbalanced Magnetic Pull Due to Simultaneous Existence of Dynamic and Static Eccentricities and Uneven Magnetization in Permanent Magnet Motors

Song, Jeong Hwan; Kang, Ki-Weon; Kang, Chiho; Jang, Gunhee

doi:10.1109/tmag.2016.2628098

Cited by 18 publications

(9 citation statements)

References 14 publications

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“…Therefore, the amplitude L  on the workpiece surface is affected by the spindle tilt angle and the turning position. In addition, the slope k of the workpiece surface caused by the inclination of the spindle axis can be expressed as equation (12).…”

Section: Umf Under Mrementioning

confidence: 99%

Theoretical prediction and experimental verification of the unbalanced magnetic force in air bearing motor spindles

Sun

Chen

et al. 2019

Proceedings of the Institution of Mechanical Engineers, Part B:

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Dynamic vibrations of air bearing motor spindles have significant influence on the surface quality in ultra-precision machining. In this article, the influence of the vibration caused by the unbalanced magnetic force on the diamond turning is investigated on the basis of the theoretical and experimental method. A permanent magnet motor model (10 poles and 12 slots) is built and then simulated to gain a periodic unbalanced magnetic force. The effects of unbalanced magnetic force on the inclination of the spindle shaft is analyzed, which would affect the surface quality of the workpiece, and the surface topography of the workpiece is predicted during an unbalanced magnetic force acting on air bearing motor spindle. The theoretical analysis and experimental turning results validate that the angle between the direction of unbalanced magnetic force and the feed direction has a certain relationship with the profile of the machined surface. Also, under different turning speeds and directions, the surface topography of the machined workpiece shows a 10-cycle-per-revolution pattern, which has good agreement with the simulations of periodic unbalanced magnetic force. This research work provides a theoretical foundation for the fault diagnosis of air bearing motor spindle caused by motor rotor eccentricity and its effect on surface generation in turning.

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Section: Umf Under Mrementioning

confidence: 99%

Theoretical prediction and experimental verification of the unbalanced magnetic force in air bearing motor spindles

Sun

Chen

et al. 2019

Proceedings of the Institution of Mechanical Engineers, Part B:

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show abstract

“…For this reason, several studies that take manufacturing errors into consideration have emerged [13][14][15][16][17][18][19]. In [13][14][15][16], analytical solutions of cogging torque are studied by considering the magnet imperfections, rotor eccentricity, geometrical variation, and magnetizing fixture.…”

Section: Introductionmentioning

confidence: 99%

“…In [13][14][15][16], analytical solutions of cogging torque are studied by considering the magnet imperfections, rotor eccentricity, geometrical variation, and magnetizing fixture. In addition, [17] mathematically investigated the cogging torque caused by the simultaneous existence of eccentricities and the uneven magnetization. Those studies have focused on analysis methods of cogging torque by considering manufacturing errors, and they reported that those errors generate additional harmonic components.…”

Section: Introductionmentioning

confidence: 99%

Mitigation Method of Slot Harmonic Cogging Torque Considering Unevenly Magnetized Permanent Magnets in PMSM

2019

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This paper presents a mitigation method of slot harmonic cogging torque considering unevenly magnetized magnets in a permanent magnet synchronous motor. In previous studies, it has been confirmed that non-uniformly magnetized permanent magnets cause an unexpected increase of cogging torque because of additional slot harmonic components. However, these studies did not offer a countermeasure against it. First, in this study, the relationship between the residual magnetic flux density of the permanent magnet and the cogging torque is derived from the basic form of the Maxwell stress tensor equation. Second, the principle of the slot harmonic cogging torque generation is explained qualitatively, and the mitigation method of the slot harmonic component is proposed. Finally, the proposed method is verified with the finite element analysis and experimental results.

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“…In the model based on the 2D analytical model output parameters of motor calculated. In [22] an analytical model introduced for cogging torque and unbalanced magnetic pull of PM motor, in the case of the simultaneous existence of dynamic and static eccentricities and uneven magnetisation. It is shown that the pole multiple ± n harmonics of the cogging torque and the unbalanced magnetic pull are generated due to the dynamic and static eccentricities.…”

Section: Introductionmentioning

confidence: 99%

Analytical modelling of the effect of pole offset on the output parameters of BLDC motor

Jafarboland

Sargazi

2018

IET Electric Power Applications

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In this study, a new analytical model is provided to calculate the effect of the pole offset on the output parameters of brushless DC (BLDC) motor. The proposed model is based on the two-dimensional analysis model and the direct solution of Laplace and Cauchy-Poisson equations for the magnetic field in the air gap and the magnets area. In this model, radial and tangential components of the magnetisation vector are calculated. Effect of pole offset on the radial and tangential components of magnetisation vector is derived. It is shown that in the case of a motor with pole offset although the length of the magnet decreases at the edges of the pole, the effective air-gap length remains constant. This study proposed two coefficients to model the reduced thickness of the magnets at the edges of the poles. Therefore, the flux density is calculated in the air gap and motor magnets. Based on the proposed model, effect of pole offset on the cogging torque ripple and back-electromotive force is achieved. These results are compared with the results of finite element and experimental tests and accuracy of the model is presented.

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Cogging Torque and Unbalanced Magnetic Pull Due to Simultaneous Existence of Dynamic and Static Eccentricities and Uneven Magnetization in Permanent Magnet Motors

Cited by 18 publications

References 14 publications

Theoretical prediction and experimental verification of the unbalanced magnetic force in air bearing motor spindles

Theoretical prediction and experimental verification of the unbalanced magnetic force in air bearing motor spindles

Mitigation Method of Slot Harmonic Cogging Torque Considering Unevenly Magnetized Permanent Magnets in PMSM

Analytical modelling of the effect of pole offset on the output parameters of BLDC motor

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