Reduction of Unbalanced Magnetic Pull in Synchronous Machines due to Parallel Circuits

Wallin, Mattias; Ranlöf, Martin; Lundin, Urban

doi:10.1109/tmag.2011.2160727

Cited by 27 publications

(13 citation statements)

References 15 publications

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“…The study found that parallel stator windings can reduce the UMF more effectively than damping windings. Wallin et al [168] used parallel circuit method to reduce UMF of a synchronous motor. The research shows that the reduction of UMF strongly depends on the relative unbalanced direction of the stator current isolation line.…”

Section: Measures To Reduce Electromagnetic Vibrationmentioning

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: Measures To Reduce Electromagnetic Vibrationmentioning

confidence: 99%

Review of Electromagnetic Vibration in Electrical Machines

Han

Chu

2018

Energies

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“…For most of the machines, the windings/coils normally have two connection methods, series connection and parallel connection. DeBortoli et al [19] Dorrell and Smith [20], and Wallin et al [ 21] indicate that the parallel connection of windings can reduce the UNF on the induction and synchronous machines. Li [22] and Liu [23] point out the UNF on the rotary SRM can be decreased with coils in parallel to weaken the noise and vibration.…”

Section: Influence Of Winding Connectionsmentioning

confidence: 99%

Influence of mover yoke and winding connections on unbalanced normal force for double‐sided linear switched reluctance machine

Wang

Chen

Tao

et al. 2016

IET Electric Power Applications

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Due to the manufacturing inaccuracies or wear, the mover eccentricity of the double-sided linear switched reluctance machine (DLSRM) is practically inevitable, which gives rise to undesirable unbalanced normal force (UNF). This study investigates the UNF reduction methods in the eccentric DLSRM. According to the finite element analysis and magnetic circuit analysis, the flux distributions and the UNF of the healthy and eccentric DLSRM are compared, and it is proved that removing the mover yoke can alleviate the UNF in the eccentric situation. Furthermore, the effects of the stator winding connections on UNF are analysed via a transient two-dimensional finite element model. It shows that the UNF can also be reduced by connecting the coils of the windings in parallel. For verifying the two proposed methods, a prototype experimental platform is established, and the experimental results validate the analyses.

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“…5 have been proposed mainly concerning some modifications in windings structure. The substantial effect of parallel stator winding in induction and synchronous machines was discussed in [8][9][10].…”

Section: Introductionmentioning

confidence: 99%