Control of Active Magnetic Bearings in Turbomolecular Pumps for Rotors with Low Resonance Frequencies of the Blade Wheel

Hutterer, Markus; Schrödl, Manfred

doi:10.3390/lubricants5030026

Cited by 12 publications

(9 citation statements)

References 17 publications

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“…The test setup with two homopolar radial magnetic bearings was controlled by independent three-phase inverters. Basically, a decoupled control of the rotor gives many degrees of freedom for advanced control [23]. However, simple decentralized PIDT1 position controllers provided sufficient performance for the following considerations.…”

Section: Measurementsmentioning

confidence: 99%

Space Vector Modulation Strategies for Self-Sensing Three-Phase Radial Active Magnetic Bearings

et al. 2019

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The focus of this study lies on the investigation of the space vector modulation of a self-sensing three-phase radial active magnetic bearing. The determination of the rotor position information is performed by a current slope-based inductance measurement of the actuator coils. Therefore, a special pulse width modulation sequence is applied to the actuator coils by a conventional three-phase inverter. The choice of the modulation type is not unique and provides degrees of freedom for different modulation patterns, which are described in this work. For a self-sensing operation of the bearing, certain constraints of the space vector modulation must be considered. The approach of a variable space vector modulation is investigated to ensure sufficient dynamic in the current control as well as the suitability for a self-sensing operation with an accurate rotor position acquisition. Therefore, different space vector modulation strategies are considered in theory as well as proven in experiments on a radial magnetic bearing prototype. Finally, the performance of the self-sensing space vector modulation method is verified by an external position measurement system.

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Section: Measurementsmentioning

confidence: 99%

Space Vector Modulation Strategies for Self-Sensing Three-Phase Radial Active Magnetic Bearings

et al. 2019

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“…However, elastic or strongly gyroscopic rotors often require coupling of the controllers of multiple AMB and more sophisticated controller structures. The gyroscopic change of the rotor behavior with its rotational speed can be tackled by partially compensating the gyroscopic coupling [1,14,15,33] or by adjusting the controller parameters with the rotational speed [5,25]. However, these controllers require a reliable measurement of the rotational speed and are often difficult to implement for highly elastic rotors.…”

Section: Introductionmentioning

confidence: 99%

Adapting the control of the magnetic bearings of a highly flexible and gyroscopic rotor to the excitations by the motor

Franz,

Schüßler,

Rinderknecht

2023

ACM

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A test rig was built to perform fatigue tests on thick-walled cylinders made of fibre reinforced plastic (FRP). During the fatigue test, the rotational speed of an FRP cylinder is periodically varied until it fails. The FRP cylinder is connected to a drive spindle that accelerates and decelerates it using a permanent magnet synchronous machine (PMSM). To avoid excessive wear, the rotor is supported by active magnetic bearings (AMB). After the fatigue test was finished with the first cylinder, a new cylinder was attached to the test stand. With this new specimen, previously uncritical radial vibrations became more severe. For high accelerations, these vibrations led to instability of the rotor. However, high accelerations are desirable to perform the fatigue tests in the shortest possible time. Hence, the AMB control should be made insensitive to these vibrations. Since the vibrations depend on the acceleration of the rotor, it is reasonable to assume that they are induced by the PMSM. To reduce the vibrations, these excitations from the PMSM are included in the model-based controller parametrization process for the radial AMB, in which the parameters are adjusted via optimization. With the adjusted control, the amplitude of the vibration was significantly reduced and higher accelerations were possible. The described parameter tuning process can easily be adapted to different AMB systems with disturbances and changes in the system.

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“…In the literature, different approaches are given for tackling the challenge. In some publications, the gyroscopic behavior is dealt with explicitly [17][18][19][20][21][22][23]; in others, it is treated as an uncertainty [12,24]. The segmentation of the sensor target leads to tangential air gaps which increase with the enlargement of the rotor (see Figure 1).…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Control Strategies for Highly Gyroscopic Outer Rotors with Diametral Enlargement in Active Magnetic Bearings

Hopf

Richter²,

Schüßler

et al. 2022

Actuators

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Flywheels are used for peak shaving or load smoothing to generate a higher efficiency and a more stable power supply. Therefore, this paper investigates highly integrated outer rotor flywheels levitated by active magnetic bearings (AMB). Due to the highly gyroscopic behavior and the diametrical enlargement under rotation, the system behavior changes with the speed, leading to a significant decrease in the maximum force and maximum force slew rate of the AMB. Thus, the speed range in which a decentralized feedback control stabilizes the system is reduced. In the literature, there are numerous approaches for coping with gyroscopic behavior. However, there are far fewer investigations for explicit consideration of the change in the air gap in the control structure. Therefore, the goal of this work is to find a control strategy to reduce the effect of the gyroscopic behavior as well as the change of the air gap. The authors propose a control strategy combining a cross feedback control with a decentralized variable feedback control. With this combination, the drawbacks of the previously described effects are compensated, leading to a higher operating range of the system and a reduced utilization of the amplifier without overcompensation at lower rotational speeds.

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Control of Active Magnetic Bearings in Turbomolecular Pumps for Rotors with Low Resonance Frequencies of the Blade Wheel

Cited by 12 publications

References 17 publications

Space Vector Modulation Strategies for Self-Sensing Three-Phase Radial Active Magnetic Bearings

Space Vector Modulation Strategies for Self-Sensing Three-Phase Radial Active Magnetic Bearings

Adapting the control of the magnetic bearings of a highly flexible and gyroscopic rotor to the excitations by the motor

Control Strategies for Highly Gyroscopic Outer Rotors with Diametral Enlargement in Active Magnetic Bearings

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