A Case Study in Control Methods for Active Magnetic Bearings

Pesch, Alexander H.; Hanawalt, Stephen P.; Sawicki, Jerzy T.

doi:10.1115/dscc2014-6257

Cited by 6 publications

(5 citation statements)

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“…The experimental results show that the μ-synthesis control can effectively suppress the aerodynamic load disturbance of the rotor and ensure the stability and stability margin of the system. Alexander et al [198] and others respectively designed PID, LQG and μ-synthesis controllers and applied them on the maglev rotor experimental platform. Through experimental comparison, it was found that the control effect of μ-synthesis controller was better than that of PID control and LQG control, and μsynthesis control The ability to suppress the vibration of the flexible mode of the rotor is better.…”

Section: Robust Controlmentioning

confidence: 99%

Magnetic Bearing: Structure, Model and Control strategy

Huang,

Li,

Zhou

et al. 2023

Preprint

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Bearings are crucial transmission components that offer support to mechanical rotating bodies. Nevertheless, traditional bearing failure due to friction and wear more easily. In scenarios involving ultra-high speeds and extreme applications, minimizing bearing losses and enhancing performance becomes especially vital. Magnetic bearings, characterized by zero friction, no need for lubrication, and high-speed capabilities, offer a viable solution to the issue of bearing failure attributed to friction. However, there is currently a shortage of comprehensive review literature that delves into the structural attributes, modeling mechanisms, and control strategies of magnetic bearings. This article will perform a comprehensive literature review on magnetic bearings, addressing the aforementioned aspects and discussing their core technologies. Firstly, from the perspective of classification and magnetic circuit structure analysis, the properties and characteristics of various magnetic bearings are discussed. Secondly, the working principle and performance of mathematical models of magnetic bearings with different structures are described, and the modeling steps and optimization schemes are summarized. Furthermore, the influence of control strategy of magnetic bearing on the control performance of magnetic bearing is summarized. Compared to PID control, modern control theory has achieved a performance improvement of nearly 50% in terms of improved position accuracy and adjustment time. Finally, the current research progress on magnetic bearings is summarized, and the current bottleneck issues are anticipated. This review contributes to a deeper understanding of the action mechanism and control method of magnetic levitation bearing, thus promoting the progress of magnetic levitation bearing technology.

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Section: Robust Controlmentioning

confidence: 99%

Magnetic Bearing: Structure, Model and Control strategy

Huang,

Li,

Zhou

et al. 2023

Preprint

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“…Control techniques have also been applied to rotating machines over the years for vibration mitigation purposes, as presented by Karakaya and Karakas (2014), Pesch et al (2014), Jung and DeSmidt (2018), Camino and Santos (2019), and Carvalho et al (2021). In general, vibration control of rotating machines can be performed based on passive, semi-active, and active strategies.…”

Section: Introductionmentioning

confidence: 99%

Active crack control approach applied to a horizontal rotating machine

Leão

Pereira

Carvalho

et al. 2022

Journal of Vibration and Control

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The present contribution proposes an active vibration control technique devoted to shafts with cracks aiming to minimize their propagation. The existence of a crack in rotating shafts can be characterized by 2 X and 3 X super-harmonic amplitudes in the vibration responses of the rotor, which can increase as the crack propagates along the shaft’s cross-section. A proportional-integral-derivative control technique is applied to suppress the 2 X and 3 X vibration amplitudes of a cracked shaft, which is performed by using a bandpass filter applied to the vibration responses of the rotor. Numerical and experimental results are obtained through both a representative finite element model of a horizontal rotor and its corresponding test-rig. In this case, electromagnetic actuators are used to apply the control effort to the rotor. The Mayes model is applied for simulating the breathing behavior of the transverse crack. The linear fracture mechanics theory is considered to correlate the crack depth with the corresponding additional rotor flexibility. Both numerical and experimental results demonstrate the possibility of reducing the effects of a transverse crack through active control on the dynamic behavior of a rotating machine. Moreover, it is shown that the proposed control law is capable of controlling the crack effects with the rotor operating in different rotation speeds.

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“…Excitation of these modes by the AMB controller is avoided by controller roll-off, which is achieved through performance weighting, as detailed in Section 2.4. More detail on the mathematical modeling and system identification of the AMB test rig can be found in the earlier study [19]. The open-loop AMB system, including the bias current, which effects the position and current stiffnesses, is inherently unstable.…”

Section: Experimental Test Rigmentioning

confidence: 99%

“…Rotor weight and an unbalance force at 2000 RPM are applied. A static unbalance is assumed to be distributed to the AMB force centers, the magnitude of which was originally tuned to rotor orbits in [19]. Initially, the TD bearing is modeled as a linear stiffness and damping on the FE rotor at the TD bearing nodes with a discontinuity to reflect if the rotor is in contact.…”

Section: Contact Force Estimation and Performance Weightmentioning

confidence: 99%

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Active Magnetic Bearing Online Levitation Recovery through μ-Synthesis Robust Control

Pesch

Sawicki

2017

Actuators

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A rotor supported on active magnetic bearings (AMBs) is levitated inside an air gap by electromagnets controlled in feedback. In the event of momentary loss of levitation due to an acute exogenous disturbance or external fault, reestablishing levitation may be prevented by unbalanced forces, contact forces, and the rotor's dynamics. A novel robust control strategy is proposed for ensuring levitation recovery. The proposed strategy utilizes model-based µ-synthesis to find the requisite AMB control law with unique provisions to account for the contact forces and to prevent control effort saturation at the large deflections that occur during levitation failure. The proposed strategy is demonstrated experimentally with an AMB test rig. First, rotor drop tests are performed to tune a simple touchdown-bearing model. That model is then used to identify a performance weight, which bounds the contact forces during controller synthesis. Then, levitation recovery trials are conducted at 1000 and 2000 RPM, in which current to the AMB coils is momentarily stopped, representing an external fault. The motor is allowed to drive the rotor on the touchdown bearings until coil current is restored. For both cases, the proposed control strategy shows a marked improvement in relevitation transients.

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A Case Study in Control Methods for Active Magnetic Bearings

Cited by 6 publications

References 0 publications

Magnetic Bearing: Structure, Model and Control strategy

Magnetic Bearing: Structure, Model and Control strategy

Active crack control approach applied to a horizontal rotating machine

Active Magnetic Bearing Online Levitation Recovery through μ-Synthesis Robust Control

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