Dynamics of a Flexible Rotor With Circumferentially Non-Uniform Magnetization Supported by a Superconducting Magnetic Bearing

Amano, Ryosuke; Kamada, Soichiro; Sugiura, Toshihiko

doi:10.1109/tasc.2013.2241377

Cited by 8 publications

(5 citation statements)

References 5 publications

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“…We theoretically predicted that there might be some difference between the resonant frequencies in two orthogonal horizontal directions at which respectful horizontal stiffnesses differ, and that there may be also some regions of the rotational frequency at which the whirl amplitude can be unstable, and that the system could show the softspring nonlinearity so that the resonant peak might bend to lower frequencies in the frequency response curve and thus a phenomenon of jump in vibration to higher amplitudes may happen near the resonance. However, from our previous numerical calculations [3], we also confirmed that an unstable region does not exist and the amplitudes in the x and y directions take their peaks simultaneously.…”

Section: Theorysupporting

confidence: 78%

“…∆ 11 , ∆ 12 , ∆ 21 and ∆ 22 are nondimensional coefficients of parametric exicitation terms and ∆ xyy , ∆ xxx , ∆ yxx and ∆ yyy are nondimensional coefficients of nonlinear terms. In our previous study [3], we discussed the force terms in the equations of motion and theoretically pointed out following significant characteristics inherent to SMB systems appearing under the condition of magnetic non-uniformity: anisotropy of its horizontal stiffnesses and periodic change of that stiffness at integral multiplication of rotational frequency which may lead to parametric excitation. We theoretically predicted that there might be some difference between the resonant frequencies in two orthogonal horizontal directions at which respectful horizontal stiffnesses differ, and that there may be also some regions of the rotational frequency at which the whirl amplitude can be unstable, and that the system could show the softspring nonlinearity so that the resonant peak might bend to lower frequencies in the frequency response curve and thus a phenomenon of jump in vibration to higher amplitudes may happen near the resonance.…”

Section: Theorymentioning

confidence: 99%

“…For mechanical design of such a rotary system, it would be better to know influence of such magnetic non-uniformity on rotordynamics, because it is conceivable that this magnetic non-uniformity can produce periodic change of electromagnetic force supporting a rotor, which may cause instability of rotor whirling. We previously investigated vibrations of the elastic shaft with and without circumferentially nonuniform magnetization distribution supported by a SMB and theoretically pointed out that anisotropy of its horizontal stiffness and periodic change of that stiffness leading to parametric excitation newly arose from magnetic non-uniformity [3]. We also found that the equations of motion of a rotor with magnetic non-uniformity supported by a SMB are equivalent to those of an asymmetrical shaft supported by a mechanical bearing [4].…”

Section: Introductionmentioning

confidence: 99%

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Influence of magnetic non-uniformity existing in a rigid rotor supported by a superconducting magnetic bearing on its whirling

Kamada¹,

Amano²,

Sugiura³

2014

J. Phys.: Conf. Ser.

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Abstract. Superconducting magnetic bearings (SMBs) have a significant feature over conventional bearings in terms of supporting a shaft without physical contact while attaining its stability without control. In their large-scale rotary applications, magnetization distribution of a rotor in the circumferential direction can be non-uniform and it would be better to know influence of such circumferential magnetic non-uniformity existing in a rotor on its dynamics, especially on its behaviors in the vicinity of the critical speed. In this study, further developing our previous research, we improved our analytical model so that we can adjust several different degrees of magnetic non-uniformity by arranging multiple magnetization vectors and investigated its influence. First, we simulated dynamical behavior of the system by numerical calculations and their results show that, with increasing the degree of magnetic non-uniformity, the whirling amplitude of the system, together with the difference of the amplitudes in the orthogonal directions in the whirling plane, get larger. Further, the rotational frequency at which the whirling amplitude takes its peak gets lower, which is caused by nonlinearity of the electromagnetic force. We carried out experiments and verified our numerical predicions.

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Section: Theorysupporting

confidence: 78%

Section: Theorymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Influence of magnetic non-uniformity existing in a rigid rotor supported by a superconducting magnetic bearing on its whirling

Kamada¹,

Amano²,

Sugiura³

2014

J. Phys.: Conf. Ser.

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“…At this point, higher requirements of smaller and of higher speed are put forward for the rotor-bearing system. 1,2 The flexible rotor-magnetic bearing system can effectively reduce the equipment weight, and wind friction loss for the magnetic bearings (MB) have several advantages, such as no friction at all operation speeds including startup and shutdown, less maintenance costs, direct control of rotor dynamics, and long life. 3,4 For the transmission dynamic systems such as the bevel gear coupled rotor system, 5 the magnetic thrust bearing (MTB) is employed to support axial load in rotating machinery to restrict the axial displacement on the occasion of the direction change for the movement.…”

Section: Introductionmentioning

confidence: 99%

Optimization and dynamic characteristics of a new type of permanent magnet bias bearing

Xiao

Xiwu

Cheng

et al. 2020

Proceedings of the Institution of Mechanical Engineers, Part C:

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Unlike traditional magnetic thrust bearings, a new type of permanent magnet biased bearing structure made of soft magnetic composites in the bevel gear coupled rotor system was proposed that requires both lower eddy currents and greater thrust force. This paper presents the optimization of structure parameters, analysis of magnetic field and dynamic stiffness for two kinds of permanent magnet biased bearing. Firstly, the structural parameters for the bearing were optimized based on the adaptive particle swarm optimization. Secondly, the dynamic magnetic flux distribution for the permanent magnet biased bearing made of carbon steel at 1000 Hz was obtained by finite element method. Then, the equivalent reluctance models for the new type of permanent magnet biased bearing considering the effect of eddy currents are derived. Finally, based on the equivalent reluctance models, the dynamic force–current factor and force–displacement factor are given. The results show that the permanent magnet biased bearing made of soft magnetic composites can provide more stable electromagnetic force and larger bandwidth in the frequency range of 1000 Hz, and have greater electromagnetic force at the same frequency comparing with that made of carbon steel.

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“…Compared with rigid rotor MB system, flexible rotor MB system allows rotor to be more slender, higher speed, which can effectively reduce the equipment weight and wind friction loss, therefore the power density and energy efficiency are greatly improved. This makes flexible rotor system supported by MB an important trend of the high-speed rotating equipment [8][9][10].…”

Section: Introductionmentioning

confidence: 99%

Design and Optimization of a Radial Magnetic Bearing for High-Speed Motor With Flexible Rotor

Fang

Wang

2015

IEEE Trans. Magn.

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The industry application of magnetic bearing (MB) has recently extended from rigid rotor system to flexible rotor system; therefore the design method of MB for flexible rotor is required. In order to reduce the inductance of the control coils and improve the dynamic performance, a radial MB with novel coils arrangements and connections is proposed in this paper. An optimal design method of the proposed MB is presented, which includes the simultaneous consideration of the MB itself, rotor-dynamics and the characteristics of the controller and power amplifier. The equivalent magnetic circuit which takes eddy current effects into considerations is used as analytical model; the damping coefficient at resonant frequency is used as the objective function. The influence of the bias flux density on the objective function is analyzed, the results show that increase the bias flux density can reduce the burden on the AMP. Practical restrictions are also imposed such as flux density constraint, maximum supply voltage of AMP, winding space constraint, pole width constraint, and copper wire capacity constraint on the design. By the optimization method of genetic algorithm and branch and bound algorithm, the optimal structure parameters of the proposed MB have been obtained. Finally, a design example is given and a prototype is manufactured. The experimental results demonstrate that the proposed MB and the optimization method are feasible and valid in the application to high speed flexible rotor.

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Dynamics of a Flexible Rotor With Circumferentially Non-Uniform Magnetization Supported by a Superconducting Magnetic Bearing

Cited by 8 publications

References 5 publications

Influence of magnetic non-uniformity existing in a rigid rotor supported by a superconducting magnetic bearing on its whirling

Influence of magnetic non-uniformity existing in a rigid rotor supported by a superconducting magnetic bearing on its whirling

Optimization and dynamic characteristics of a new type of permanent magnet bias bearing

Design and Optimization of a Radial Magnetic Bearing for High-Speed Motor With Flexible Rotor

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