• Title, Summary, Keyword: Rotor eccentricity

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Electromechanical Characteristics of a Squirrel Cage Induction Motor due to Broken Rotor Bars and Rotor Eccentricity (회전자 바 개방과 회전자 편심에 의한 단삼 유도 전동기의 전기 및 기계적 특성 해석)

  • Park, Sang-Jin;Jang, Jeong-Hwan;Jang, Geon-Hui;Lee, Yong-Bok;Kim, Chang-Ho
    • The Transactions of the Korean Institute of Electrical Engineers B
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    • v.51 no.8
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    • pp.425-433
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    • 2002
  • This research investigates the electromechanical characteristics of a sing1e-phase squirrel cage induction motor due to broken rotor bars and rotor eccentricity. Numerical analysis is performed by solving the nonlinear time-stepping finite element equation coupled with the magnetic field equation, circuit equation and mechanical equation of motion. It shows that the asymmetry of magnetic flux due to the broken rotor bars and rotor eccentricity introduce a change in the stator current, torque, speed, magnetic force and vibration of a rotor at the same time. However, even in the existence of rotor eccentricity, 3 broken rotor bar introduces a dominant change in the magnetic force and rotor displacement, i.e., beating phenomenon in time domain and sideband frequencies in frequency spectra, respectively.

Dynamic Analysis of Rotor Eccentricity in Switched Reluctance Motor with Parallel Winding

  • Li, Jian;Choi, Da-Woon;Cho, Yun-Hyun
    • Proceedings of the KIPE Conference
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    • pp.85-87
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    • 2008
  • This paper presents dynamic characteristics in Switched Reluctance Motor (SRM) with rotor eccentricity and proposes the reduction method of rotor eccentricity effects by the different winding connections. These characteristics investigations are computed by 2D transient magnetic FEM analysis coupled with external circuits. The radial and unbalance magnetic force in the stator, which is the main exciting force of the vibration, is calculated using Maxwell stress method and compared with the performance characteristics according to the serial and parallel connections of windings. The influence of winding method counteracting unbalance forces on the rotor vibration behavior is estimated by the current waveforms of the paralleled paths under rotor eccentricity.

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Analytical Performance Modelling of Slotted Surface-Mounted Permanent Magnet Machines with Rotor Eccentricity

  • Yan, Bo;Wang, Xiuhe;Yang, Yubo
    • Journal of Electrical Engineering and Technology
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    • v.12 no.2
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    • pp.778-789
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    • 2017
  • This paper presents an improved subdomain method to predict the magnet field distributions and electromagnetic performance of the surface-mounted permanent magnet (SPM) machines with static or dynamic eccentricity. Conventional subdomain models are either based on the scalar magnet potential to predict the rotor eccentricity effect or dependent on the magnetic vector potential without considering the eccentric rotor. In this paper, both the magnetic vector potential and the perturbation theory are introduced in order to accurately calculate the effect of rotor eccentricity on the open-circuit and armature reaction performance. The calculation results are presented and validated by the corresponding finite-element method (FEM) results.

Influence of Thermal Expansion on Eccentricity and Critical Speed in Dry Submersible Induction Motors

  • Lv, Qiang;Bao, Xiaohua;He, Yigang
    • Journal of Electrical Engineering and Technology
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    • v.9 no.1
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    • pp.106-113
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    • 2014
  • Rotor eccentricity is one of the major factors that directly influence the security of horizontal electrical machines, and the critical speed of the shaft has a close relationship with vibration. This paper deals with the influence of thermal expansion on the rotor eccentricity and critical speed in large dry submersible motors. The dynamic eccentricity (where the rotor is still turning around the stator bore centre but not its own centre) and critical speed of a three-phase squirrel-cage submersible induction motor are calculated via hybrid analytical/finite element method. Then the influence of thermal expansion is investigated by simulation. It is predicted from the study that the thermal expansion of the rotor and stator gives rise to a significant air-gap length decrement and an inconspicuous slower critical speed. The results show that the thermal expansion should be considered as an impact factor when designing the air gap length.

Analysis of the Eccentric Characteristics of the Brushless Motor by the Rotor Structure (회전자 구조에 따른 브러시리스 모터 편심 특성 분석)

  • Son, Byoung-Ook;Lee, Ju
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.24 no.12
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    • pp.156-163
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    • 2010
  • The brushless motor is getting widely applied to the automotive component with the advantage of the high efficiency, high reliability and etc.. Most of the motor applications require the low vibration and acoustic noise. The cogging torque is the one of the main cause of the noise and vibration. The step-skewed rotor is used to reduce the cogging torque. We analyze the characteristics of the step-skewed rotor and non skewed rotor with the same stator by using 2-dimensional FEM. And then we analyze the characteristics variation according to the rotor eccentricity. The prototype is made and tested. As the results, the step-skewed rotor structure reduce the cogging torque and local radial force but it is more sensitive to rotor eccentricity.

Characteristics Analysis on the Effects of Rotor Eccentricity in Squirrel-cage Induction Motor (회전자 편심을 고려한 농형 유도전동기의 특성해석)

  • Kim, Mi-Jung;Kim, Byong-Kuk;Hwang, Don-Ha;Kang, Dong-Sik;Cho, Yun-Hyun
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.56 no.2
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    • pp.289-294
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    • 2007
  • This paper describes the effects of rotor eccentricity in squirrel cage induction machines. Asymmetric electro-magnetic force caused by the frictional worn bearing, rotor misalignment and unbalanced rotor etc. generates an asymmetrical operation, vibration and electro-magnetic noise. The need for detection of these rotor eccentricities has pushed the development of monitoring methods with increasing sensitivity and noise immunity. In this paper, we focus on investigating the asymmetrical operation considering of unbalanced magnetic pull in squirrel-cage induction motor with 380 [V], 7.5 [kW], 4P, 1,768 [rpm]. The effects of the non-symmetric rotor and magnetic force are simulated by finite element method (FEM) and tested using search coils for measuring the actual air-gap flux.

Comparison of Vibration Characteristics in IPM and SPM BLDC Motors with Rotor Eccentricity : (1) Electro-magnetic Force Due to PM (회전자 편심을 가지는 IPM, SPM 전동기 진동 특성 비교: (1) 영구 자석에 의한 전자기력)

  • 황근배;김경태;황상문
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.11 no.9
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    • pp.454-461
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    • 2001
  • Acoustic noise and vibration of a BLDC motor is a coupled phenomenon between mechanical characteristics and electromagnetic origins through the motor air-gap. When a relative misalignment of rotor in the air-gap center exists on the assemblage, it is considered to influence the motor system characteristics. In this paper, the back electro motive force(BEMF) is analyzed by Finite Element Method(FEM) and verified by experiments for the SPM and IPM type motors. For magnetic field analysis, a FEM is used to account for the magnetic saturation. Using these results, the FEM is made to determine the appropriate electromagnetic field analysis in BLDC motors with rotor eccentricity ratio. A radial magnetic imbalance force of BLDC motor with rotor eccentricity is analyzed. Results demonstrate that the imbalance force is increased according to the degree of misalignment. An IPM motor, mostly chosen to realize high-speed operation, shows a worse effect on magnetic unbalanced forces and dynamic responses compared with SPM motor due to magnetic saturation when the rotor eccentricity exists.

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Inductances Evaluation of a Squirrel-Cage Induction Motor with Curved Dynamic Eccentricity

  • Lv, Qiang;Bao, Xiaohua;He, Yigang;Fang, Yong;Cheng, Xiaowei
    • Journal of Electrical Engineering and Technology
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    • v.9 no.5
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    • pp.1623-1631
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    • 2014
  • Eccentricity faults more or less exist in all rotating electrical machines. This paper establishes a more precise model of dynamic eccentricity (DE) in electrical machines named as curved dynamic eccentricity. It is a kind of axial unequal eccentricity which has not been investigated in detail so far but occurs in large electrical machines. The inductances of a large three-phase squirrel-cage induction machine (SCIM) under different levels of curved DE conditions are evaluated using winding function approach (WFA). These inductances include the stator self and mutual inductances, rotor self and mutual inductances, and mutual inductances between stator phases and rotor loops. A comparison is made between the calculation results under curved DE and the corresponding pure DE conditions. It indicates that the eccentricity condition will be more terrible than the monitored eccentricity based on the conventional pure DE model.

Effect of friction and eccentricity on rebbing phenomenon (회전마멸현상에서의 마찰과 편심의 영향)

  • 최연선;김준모;정호권
    • Journal of KSNVE
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    • v.6 no.6
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    • pp.819-825
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    • 1996
  • Nonlinear dynamic characteristics of rubbing phenomenon in rotor dynamics are investigated experimentally and numerically. Rubbing phenomenon occurs when rotor contacts with stator during whirling and causes the large amplitude of vibration, high whirl frequencies, and possibly catastrophic failure. Rubbing has various types of forward whirl, backward rolling, backward slipping, and partial rub depending on the system parameters of rotating machinery and running speed. Experiments are performed for forward whirl and backward whirl. And numerical analysis are conducted to explain the changes between backward rolling and backward slipping. Experimental and numerical results show that the types of whirling motion depends on the friction coefficient between rotor and stator and the eccentricity of rotor.

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Characteristics Analysis on the Effects of Rotor Eccentricity in Squirrel-cage Induction Motor (회전자 편심을 고려한 농형 유도전동기의 특성해석)

  • Kim, Mi-Jung;Kim, Byong-Kuk;Jo, Won-Young;Cho, Yun-Hyun;Hwang, Don-Ha;Kang, Dong-Sik
    • Proceedings of the KIEE Conference
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    • pp.188-190
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    • 2006
  • This paper describes the effects of air gap eccentricity in induction machines. Asymmetric electro-magnetic force caused by the frictional worn bearing, rotor misalignment and unbalanced rotor etc. generates an asymmetrical operation, vibration and electro-magnetic noise. The need for detection of these rotor eccentricities has pushed the development of monitoring methods with increasing sensitivity and noise immunity. In this paper, we focus on investigating the asymmetrical operation considering of unbalanced magnetic force in squirrel-cage induction motor with 380 [V], 7.5 [kW], 4P, 1,768 [rpm]. The effects of the rotor eccentricity, magnetic force are investigated by finite element method (FEM).

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