Unbalanced Magnetic Force Analysis in Eccentric Surface Permanent-Magnet Motors Using an Improved Conformal Mapping Method

Rezaee‐Alam, Farhad; Rezaeealam, Behrooz; Faiz, Jawad

doi:10.1109/tec.2016.2623566

Cited by 46 publications

(19 citation statements)

References 26 publications

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“…Hanic et al [95] proposed a novel method for magnetic field analysis based on the CMM and MEC. Alam et al [121,122] took the slotting effect, winding distribution, armature reaction and saturation effect into account. They presented an improved CMM for magnetic field analysis in surface-mounted permanent magnet motors considering eccentricities.…”

Section: Conformal Mapping Methodsmentioning

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: Conformal Mapping Methodsmentioning

confidence: 99%

Review of Electromagnetic Vibration in Electrical Machines

Han

Chu

2018

Energies

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“…Factors, such as the non-uniform magnetization of a permanent magnet (PM) and the eccentricity were considered. Farhad Rezaee-Alam has calculated and analyzed the UMF in eccentric surface-mounted permanent-magnet motors under various eccentricity conditions (Rezaee-Alam et al, 2016). In this paper, the UMF is utilized as an excitation force in order to measure the dynamic characteristics of a turbomachine.…”

Section: Introductionmentioning

confidence: 99%

Frequency response function measurement of a rotor system utilizing electromagnetic excitation by a built-in motor

Ren

Tsunoda

Han

et al. 2020

JAMDSM

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In this paper, we propose a practical method for evaluating the robustness and stability of rotating machines. This entails using electromagnetic excitation and measuring the frequency response functions (FRFs) of the rotor system during rotation. The difficulty of applying excitation can be solved by utilizing a built-in motor with static eccentricity and adding a sinusoidal sweep d-axis current to the motor. A test rig with a bearingless motor (BELM) was used to verify the validity of the proposed method. A consequent-pole-type BELM is a combination of a consequent-pole-type motor and a radial magnetic bearing, in which both the motor and the suspension windings are arranged in one stator core of the BELM. The center of the motor is defined by the zero-power controller and the static eccentricity is determined by the suspension control system. The FRFs measured utilizing the electromagnetic excitation generated by the motor windings was compared with reference FRFs measured utilizing the suspension windings. The natural frequencies and damping ratios were determined from the two different FRFs. The difference between the identified natural frequencies and the difference between the damping ratios for the two different FRFs were calculated. The effectiveness of measuring the dynamic characteristics of the rotor system under various rotational conditions, such as the rotational speed and eccentricity, was clarified and the differences between the measurements obtained from the two different FRFs were generally less than 7.7%.

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“…On the other hand, LPMCM is often used to analyze the nonlinear iron core. From the LPMCM solution, the airgap length and slot opening are modified to represent the magnetic potential drops of the stator [14]- [16]. Then the complex permeance based on the modified airgap and slot opening was introduced to account for both saturation effect and slotting effect.…”

Section: Introduction Ermanent-magnetmentioning

confidence: 99%

“…Then the complex permeance based on the modified airgap and slot opening was introduced to account for both saturation effect and slotting effect. Nevertheless, these models in [14]- [16] are time-consuming due to the calculation of the saturated complex permeance using SC transformation at every rotor position.…”

Section: Introduction Ermanent-magnetmentioning

confidence: 99%