• The Transactions of the Korean Institute of Electrical Engineers B
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• v.55 no.8
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• pp.408-415
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• 2006

This paper deal with control and design of 50,000rpm class Active Magnetic Bearing(AMB) system for high speed precision motor. In the design of AMB system, the design parameters adopted high robust rotor shaft, Active Magnetic Bearing, sensor and control system. In the design of Magnetic Bearing, 2-D Finite Element Method(FEM) is used and transfer matrix method is using for rotor dynamics. The control accuracy of high speed AMB system is demonstrated by experimentations.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2004.10a
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• pp.457-462
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• 2004

Active magnetic bearings (AMB's) have become practical in many industrial fields and numbers of studies for magnetic bearing systems have been reported. However, AMB systems are open-loop unstable and thus require feedback control for robust stabilization and performance. In this paper, first, a rotation of the rotor around the inertial axis is considered and a rigorous modeling of a magnetic bearing system in which the rotation of the rotor is on its axis of inertia is developed. Next, to stabilize the AMB system a PID controller is used and experimentally analyze its rotational response.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.12 s.243
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• pp.1567-1573
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• 2005

This paper introduces a new active magnetic bearing(AMB) that can provide both radial and axial control functions in one bearing unit without axial disk. It has a structure of double four-pole AMB or a four-pole AMB where each core is split into two axially. The cores have two kinds of coil winding; they independently generate fluxes on the planes perpendicular or parallel to the shaft. For the radial control action, it works just like a conventional four-pole AMB. Meanwhile, for the axial control, it uses the Lorentz force generated by the interaction of the bias flux for radial control and the axial control flux. In this paper, the proposed structure, principle, and design process based on magnetic flux analysis are introduced, and its feasibility is experimentally verified by using a simple PD control algorithm with a feedforward loop to compensate the coupled flux effect.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.79-83
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• 2001

A cone-shaped active magnetic bearing spindle system for high speed internal grinding is designed and tested. The cone-shaped AMB system consists of only 4 couples of magnet, it can be smaller and lighter than conventional radial-axial-type AMB system. In this paper, the cone-shaped electromagnets are designed by magnetic circuit theory, and de-coupled direct feedback PID controller is applied to control the coupled magnetic bearings. The designed cone-shaped AMB spindle system is built and constructed with a digital control system, and tested its stbility and dynamic performances. As the results of the tests, this spindle runs up to 40,000 rpm with about 5 ${\mu}{\textrm}{m}$ of runout, and the AMB system provides high damping ratio eliminating overshoot and resonance speed.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.15 no.3 s.96
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• pp.364-370
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• 2005

The active magnetic bearing (AMB) systems mounted in moving vehicles are exposed to the disturbances due to the base motion, often leading to malfunction or damage as well as inaccurate positioning of the systems. Thus, in the controller design of such AMB systems, robustness to base disturbances becomes an essential requirement. In this study, effective control schemes are proposed for the homo-polar AMB system, which uses permanent magnets for generation of bias magnetic flux, when it is subject to base motion, and its control performance is experimentally evaluated. The base motion of AMB system is modeled as the dynamic disturbances in the gravity and base excitation forces. To effectively compensate for the disturbances, the angle feed-forward controller based on the inverse dynamic model and the acceleration feed-forward controller based on the normalized filtered-X LMS algorithm are proposed. The performance test of the prototype AMB system is carried out, when the system is mounted on rate table. The experimental results show that the performance of the proposed controllers for the AMB system is satisfactory in compensating for the disturbances due to the base motion.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.11a
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• pp.486-489
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• 2004

The active magnetic bearing (AMB) systems mounted in moving vehicles are exposed to the disturbances due to the base motion, often leading to malfunction or damage as well as inaccurate positioning of the systems. Thus, in the controller design of such AMB systems, robustness to base disturbances becomes an essential requirement. In this study, effective control schemes are proposed for the homo-polar AMB system, which uses permanent magnets for generation of bias magnetic flux, when it is subject to base motion, and its control performance is experimentally evaluated. The base motion of AMB system is modeled as the dynamic disturbances in the gravity and base excitation forces. To effectively compensate for the disturbances, the angle feed-forward controller based on the inverse dynamic model and the acceleration feed-forward controller based on the normalized filtered-X LMS algorithm are proposed. The performance test of the prototype AMB system is carried out, when the system is mounted on rate table. The experimental results show that the performance of the proposed controllers for the AMB system is satisfactory in compensating for the disturbances due to the base motion.

• Progress in Superconductivity
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• v.13 no.3
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• pp.195-202
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• 2012

In this paper, we designed Active Magnetic Bearing (AMB) for large scale Superconductor Flywheel Energy Storage System (SFESS) and PD controller for AMB. And we experimentally evaluated SFESS including hybrid type AMB. The radial AMB was designed to provide force slew rate that was sufficient for the unbalance disturbances at the maximum operating speed. The thrust AMB is a hybrid type where a permanent magnet carries the weight of the flywheel and an electromagnetic actuator generates the dynamic control force. We evaluated the design performance of the manufactured AMB through comparison of FEM analysis and the results of experimental force measurement. In order to obtain gains of PD controller and design a notch filter, the system identification was performed through measuring frequency response including dynamics for the AMBs, a power amp and a sensor using a sine swept test method after levitating the flywheel. Through measuring the current input of the AMBs and the orbit of a flywheel according to rotational speed, we verified excellent control performance of the AMBs with small amount current for the large scale SFESS.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.12 s.243
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• pp.1561-1566
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• 2005

In this paper, a new compact active magnetic bearing(AMB) is proposed in which radial and axial bearings are integrated in one bearing unit. It consists of four U-shaped cores circumferentially connected by yokes and two-layer coils for radial and axial controls. For the radial control action, it has the same principle as conventional homopolar AMBs, while for the axial control, it uses the Lorentz force generated by the interaction of the bias flux for radial control and the axial control flux. The proposed structure makes it easy to design a compact AMB because it has no disk for axial control. This paper introduces the proposed structure, principle, and design process based on the magnetic flux analysis. By using a control algorithm with feedforward action to compensate the coupled flux effect, the feasibility of the proposed AMB is experimentally verified.

• Journal of the Korean Institute of Intelligent Systems
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• v.9 no.6
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• pp.598-604
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• 1999

A new fuzzy control algorithm for the control of active magnetic bearing (AMB) systems is proposed in th~sp aper. It combines PDC algorithm based on the LMI design of Joh et al. [4,5] and Mamdani-type control rules using fuzzy singletons to handle the nonlinear characteristics of AMB systems efficiently. They are named fine mode control and coarse mode control, respectively. The coarse mode control yields fast response for large deviation of the rotor and the fine mode control gives desired transient response for small deviation of the rotor. The proposed algorithm is applied to an AMB system to verify the performance of the proposed method. The comparison of the proposed method with a linear controller using a linearized model about the equilibrium point and the PDC algorithm show the superiority of the proposed algorithm.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.4
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• pp.797-802
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• 2010

In this paper, a systematic procedure to design a nonlinear controller for nonlinear active magnetic bearing (AMB) systems is presented. To do this, we effectively convert the AMB system into a polytopic quasi-linear parameter varying (LPV) system, which is a representation of nonlinear state-space models and is described by the convex combination of a set of precisely known vertices. Unlike the existing quasi-LPV systems, the nonlinear weighting functions, which construct the polytopic quasi-LPV model of the AMB system by connecting the vertices, include not only state variables but also the input ones. This allows us to treat the input nonlinearity effectively. By means of the derived polytopic quasi-LPV model and linear matrix inequality (LMI) conditions, nonlinear controller that stabilizes the AMB system is obtained. The effectiveness of the proposed controller design methodology is finally demonstrated through numerical simulations.