Bearingless Five-Axis Rotor Levitation with Two Pole Pair Separated Conical Motors (original) (raw)
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2011 IEEE Energy Conversion Congress and Exposition, 2011
In standard motor applications, rotor suspension with traditional mechanical bearings represents the most economical solution. However, in certain high performance applications, rotor suspension without contacting bearings is either required or highly beneficial. Examples include applications requiring very high speed or extreme environment operation, or with limited access for maintenance. This paper expands upon a novel bearingless motor concept, in which two motors with opposing conical air-gaps are used to achieve full five-axis levitation and rotation of the rotor. Force in this motor is created by deliberately leaving the motor's pole-pairs unconnected, which allows the creation of different d-axis flux in each pole pair. This flux imbalance is used to create lateral force. This approach is different than previous bearingless motor designs, which require separate windings for levitation and rotation. This paper examines the predicted and achieved suspension performance of a fully levitated prototype bearingless system. I.
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IEEE/ASME Transactions on Mechatronics, 2012
In this paper, the principles of motor torque and suspension force generation in bearingless brushless motors with high pole numbers are explained, graphically illustrated, and analyzed in detail. The necessary harmonic components of the flux density distribution in the air gap are calculated and it is visualized how these can be generated by superposition of harmonics depending on a specific rotor pole/stator slot ratio. Especially, for bearingless motors with a fractional pole/slot ratio, it is shown how superior and precise suspension performance and high rotational speeds can be achieved. A basic analytical model is introduced and the considerations are exemplified for a 26-pole/24-slot bearingless brushless single-layer motor with concentrated windings compared to alternative feasible configurations. Adequate performance criteria for the motor as well as the bearing comparison are defined.
In this paper the principles of motor torque and suspension force generation in bearingless brushless motors with high pole numbers are explained, graphically illustrated and analyzed in detail. The necessary harmonic components of the flux density in the air-gap are calculated and it is visualized how these can be generated by superposition of harmonics depending on a specific rotor pole / stator slot ratio. Especially, for bearingless motors with a fractional pole / slot ratio, it is shown how superior suspension performance and high rotational speeds can be achieved. The considerations are exemplified for a 26-pole / 24-slots bearingless brushless motor.
Magnetically Levitated Homopolar Hollow-Shaft Motor
IEEE/ASME Transactions on Mechatronics, 2000
This paper describes a novel and compact topology for contactless levitation and rotation of a wide annular rotor through the walls of a sealed process chamber. In the proposed setup, a homopolar magnetic bearing biased by permanent magnets is combined with a high-pole-number segment motor. The paper discusses the functional principle of the motor, and gives design and optimization guidelines for the bearing and the drive unit, respectively. An experimental system is presented along with a set of measurement results verifying the theoretical considerations.
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IEEE Transactions on Industrial Electronics, 2014
Active magnetic bearings enable contactless operation and can therefore be used for supporting rotors spinning at high speeds. However, the rotational speed in conventional reluctance-force-based magnetic bearing topologies is limited, which is mainly due to high rotor losses and limited force control bandwidths. In this paper, a prototype of a self-bearing motor is presented, which overcomes several limitations of state-of-the-art high-speed magnetically levitated electric drive systems. Due to the employed magnetic bearing, the motor can be operated in high-purity or vacuum environments. An analytical mechanical and electrical bearing model is introduced and verified by measurements. Furthermore, a bearing inverter system is designed, and its controller performance is shown. Measurements of spinning levitated rotors up to speeds of 505 000 r/min verify the functionality of the overall system. To the authors' knowledge, this is the highest speed achieved by magnetically levitated electrical drive systems so far.
Design and Development of a 26-Pole and 24-Slot Bearingless Motor
IEEE Transactions on Magnetics, 2000
Several processes in chemical, pharmaceutical, biotechnology and semiconductor industry require contactless levitation and rotation through a hermetically closed process chamber. A highly interesting topology for these applications is the "bearingless slice motor" concept, where already some research has been done in the past. This paper presents the design, optimization and development of a 26-pole and 24-slot bearingless motor, which promises high acceleration and bearing performance and an ultra-compact setup. A prototype with a large rotor diameter and a large air-gap has been built to verify the simulation results by experiments.
Permanent magnet bearingless motors: Modelling, design and drive
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In this paper, the authors give a general description of bearingless machines and the origin of the ripples of the levitation force. Magnetic model using spectral analysis of the air-gap flux density is developed to identify the forces ripples and their origins. The authors propose two ways to suppress the force ripples. The first one can be performed during the design process of the machine while the second one can be applied with the supply via a control loop and an active harmonic suppression.
Analysis and design of an ultra-high-speed slotless self-bearing permanent-magnet motor
Iecon 2012 38th Annual Conference on Ieee Industrial Electronics Society, 2012
Active magnetic bearings (AMB) enable contactless operation and can therefore be used for supporting rotors spinning at high speeds. However, the rotational speed in conventional reluctance-force-based AMB topologies is limited which is mainly due to high rotor losses and achievable force control bandwidths. In this paper, a prototype of a self-bearing motor designed for rotational speeds of up to 500 000 revolutions per minute (rpm) is presented. Due to the employed AMB, the motor can be operated in high-purity or vacuum environments. An analytical mechanical and electrical bearing model is introduced and verified by measurements. Furthermore, a bearing inverter system is designed and its controller performance is shown. Closed-loop system measurements of a spinning levitated rotor at 400 000 rpm verify the functionality of the overall system. To the authors knowledge, this is the world record speed for magnetically-levitated electrical drive systems.