Levitation performance of two opposed permanent magnet pole-pair separated conical bearingless motors (original) (raw)
Related papers
Bearingless Five-Axis Rotor Levitation with Two Pole Pair Separated Conical Motors
2009 IEEE Industry Applications Society Annual Meeting, 2009
In some high performance applications, such as high speed rotating machinery, systems where access for maintenance is limited, or operating environments with extreme temperatures and pressures, motors without mechanical bearings would be preferred. This paper presents the theory, simulation, and lab results of a new type of fully magnetically levitated bearingless motor. The motors are wound without internally connecting the pole pairs, and force is controlled by varying rotor reference frame d-axis current to each pole pair. This in turn raises or lowers the flux caused by the permanent magnets, creating a flux imbalance on the periphery of the rotor [1], which in turn creates a net force on the rotor. The conical shape of the motor allows forces to be created in both radial and axial directions, allowing these motors full 5-axis levitation.
Motor Torque and Magnetic Levitation Force Generation in Bearingless Brushless Multipole Motors
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.
Basic characteristics of a consequent-pole-type bearingless motor
IEEE Transactions on Magnetics, 2005
In this paper, the basic characteristics of a consequent-pole bearingless motor are described. The consequent-pole type rotor has buried permanent magnets polarized in the same radial direction. An analysis is carried out to find the optimum pole number for the machine to produce stable magnetic suspension. The results indicate that there is decoupling of the radial suspension forces from the drive torque when eight or more poles are used. A comparison is given for the torque and suspension force generation with respect to a conventional surface-mount PM rotor. It is shown that the suspension force is several times higher for the consequent-pole rotor; however the torque decreases by 12%. A test machine was built and the torque and suspension characteristics were confirmed. Comparison is also made with other conventional bearingless motors.
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
2017 IEEE Workshop on Electrical Machines Design, Control and Diagnosis (WEMDCD), 2017
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.
A Wide Air Gap Flux Switching Bearingless Motor With Odd and Even Pole Pair Numbers
IEEE Open Journal of Industry Applications
This paper introduces a bearingless motor topology with a magnet-free rotor that provides a higher rotor torque density and wider magnetic air gap compared to previously published topologies. The stray flux is minimized by using a stator with only eight teeth in temple configuration that contain permanent magnets. The motor performance is analyzed based on experimental prototypes, that were designed using 3D FEM simulations, for even and odd rotor pole pair numbers of six and nine, respectively. Control schemes that compensate parasitic radial forces to achieve stable magnetic levitation of the rotors are presented. The implemented prototypes reached a rotational speed of 2000 rpm and a maximum torque of 8 Nm. INDEX TERMS Flux switching, high torque, magnetic levitation, reluctance rotor, temple motor, wide air gap machine.
Several processes in chemical, pharmaceutical, biotechnology and semiconductor industry require contactless levitation and rotation through a hermetically closed chamber wall. This paper presents a novel concept that combines crucial advantages such as high acceleration capability, large air gap and a compact motor setup. The basic idea is to separate a homopolar bearing unit axially from a multipolar drive unit on two different height levels. Hence, the proposed concept is denominated as "bearingless 2-level motor". In this paper, the bearing and drive functionalities are explained in detail and design guidelines are given based on analytic equations and electromagnetic 3D simulations. Furthermore, the influence of non-idealities such as saturation and coupling effects are evaluated and included in the design. Finally, measurements on an experimental prototype exemplify the design considerations and prove the excellent performance of the new concept.