Towards fault-tolerant active control of rotor–magnetic bearing systems

Cole, Matthew O. T.; Keogh, Patrick; Şahinkaya, M. Necip; Burrows, C. R.

doi:10.1016/s0967-0661(03)00173-4

Cited by 42 publications

(28 citation statements)

References 7 publications

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“…It is also anticipated that the recovery controller will yield low bearing static stiffness and therefore poor steady-state support. Therefore, a switching scheme is utilized for implementation of the recovery controller [4]. In AMB systems, for safety reasons, it is common to set a deflection limit at which power is removed from the AMBs and motor, in order to prevent the loss of stability.…”

Section: Results Of Controller Implementationmentioning

confidence: 99%

“…The situation is exacerbated by the coincidence of unbalance forces. Second, shaft contact with the touchdown (TD) bearings while rotating will impart other forces on the rotor and may result in a so-called contact mode of vibration [4]. TD bearings are usually traditional bearings that are oversized for the shaft and do not touch the shaft during levitation but rather catch the shaft in the event of levitation failure.…”

Section: Introductionmentioning

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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Section: Results Of Controller Implementationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

Pesch

Sawicki

2017

Actuators

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“…A comprehensive study of fault scenarios for AMBs is provided in [5] where faults are categorized by type, effect and feasibility of fault tolerance. From the study of these scenarios three fault categories emerge that are not related to the rotor and are not dependent on physical redundancy for fault tolerant behaviour: actuator faults & failures; sensor faults & failures; software errors.…”

Section: Introductionmentioning

confidence: 99%

“…Much attention have been devoted to sensor faults, see e.g. [4], [5], [12], [13], [16]. To ensure fault tolerance with respect to the AMBs both sensor and actuator faults must be mitigated.…”

Section: Introductionmentioning

confidence: 99%

Fault diagnosis of active magnetic bearings based on Gaussian GLRT detector

Nagel

Galeazzi

Voigt

et al. 2016

2016 3rd Conference on Control and Fault-Tolerant Systems (SysTol)

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Abstract-Active magnetic bearings are progressively replacing conventional bearings in many industrial applications, particularly in the energy sector. Magnetic bearings have many advantages such as contactless support and clean operation; however their use poses also some challenges connected to their inherent open loop instability. Occurrence of faults in one or more components of an active magnetic bearing may lead to loss of control of the rotor. Timely detection and isolation of faults in an active magnetic bearing could prevent hazardous system's behaviours by enabling proper reconfiguration of the control system. A structural model of the bearing-rotor system is presented and used to perform a detectability and isolability analysis of faults in the magnetic actuator. Structural detectability and group-wise isolability is concluded for single and multiple faults in the actuator. A Gaussian generalized likelihood ratio test is proposed for detecting faults striking the electromagnet. The detector is capable to detect and isolate the occurrence of faults in e.g. the windings of bearing by tracking changes in the mean value of a Gaussian distribution. The statistical distribution of the residuals in non faulty condition is characterized by experimental data of a full-scale bearingrotor system. Verification of the detection performance is done through simulated data of a nonlinear model of the magnetic bearing calibrated against the real system.

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“…Many research activities have concentrated on developing adaptive magnetic bearing controllers to prevent the rotor contact with auxiliary bearings under transient loading, or if the contact does occur, to minimize the impact damage and to recover the rotor position as quickly as possible without the necessity to shut down the system [2,3]. Fault detection and tolerance systems mainly concentrate on identifying faults in sensors or magnetic bearing coils, and are usually based on a stochastic approach [4][5][6]. Sahinkaya [7] investigated fault detection at rotor systems with active magnetic bearings.…”

Section: Introductionmentioning

confidence: 99%

On the optimization problem of model-based monitoring

Ginzinger

Şahinkaya

Heckmann

et al. 2011

Sci. China Technol. Sci.

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Today there is a big interest in reducing the maintenance costs and in increasing the reliability of machines in continuous operation. Therefore, maintenance on condition is used. State-of-the-art is a trend analysis and a fault prediction made only based on sensor signals and stochastic methods. The identification possibilities of this technique are limited. A new concept for model-based monitoring has been developed for more detailed fault identification. The developed concept determines the condition of a machine after the occurrence of a fault. The concept is based on a simulation including various faults and an optimization tool. The development of a cost function and the optimization is one of the challenges of such a concept. Using an AMB rotor system with an auxiliary bearing, the new concept of model-based monitoring is investigated using experiments and the optimization is discussed in this paper. model-based monitoring, rotordynamics, optimizationCitation: Ginzinger L, Sahinkaya M N, Heckmann B, et al. On the optimization problem of model-based monitoring.

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Towards fault-tolerant active control of rotor–magnetic bearing systems

Cited by 42 publications

References 7 publications

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

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

Fault diagnosis of active magnetic bearings based on Gaussian GLRT detector

On the optimization problem of model-based monitoring

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