Levitation and torque control of internal permanent magnet type bearingless motor

The interaction between the current space vector producing torque and the one producing radial forces in a multiphase bearingless Surface-Mounted Permanent Magnet Synchronous Motors (SPMSM) is investigate. In fact, due to the spatial harmonic content of the stator mmf and the rotor magnets, it is necessary to consider not only the mutual effect between the magnetic field related to a single stator current space vector and the rotor magnetic field produced by the magnets, but also to take into account the coupling between the different stator current space vectors, that give non predictable effects on the radial forces distribution. The purpose of this work is to create a model allowing to predict amplitude and direction of the force produced in "bearingless" motors. This will give a powerful tool for the design of the levitation control system. An analytical model to calculate the radial forces is presented, based on the Fourier series harmonic distribution, considering all the interactions between the magnetic fields given by every stator current space vector and by rotor magnets. The accuracy of calculations is then verified by comparing the obtained results with FE analysis.

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“…One of them can be used to control the torque, as in [5]. The additional degrees of freedom can be used to produce levitation forces [6], [7].…”

Section: K Cmentioning

confidence: 99%

Analytical model of radial forces considering mutual effects between torque and levitation current space vectors in 5-phase PM bearingless motors

Serri

Tani

Serra

2013

IECON 2013 - 39th Annual Conference of the IEEE Industrial Electronics Society

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“…The total levitation force in the 0 = 0 direction is calculated by the y component of attractive force as follows: (4) where L is the length of rotor, r is the radius of rotor, and p, o is the permeability of free space. …”

Section: Radial Type Levitated Motormentioning

confidence: 99%

Magnetically Levitated Motor for Rotary Blood Pumps

et al. 1997

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The noncontact rotary pumps under development for use as artificial heart pumps are highly efficient and can prevent thrombus formation. In these pumps magnetic bearings have been widely used to support the rotors to avoid any physical contact. The use of magnetic bearings, however, has led to requirements for the control of a large degree of freedom and for a separate driving motor. This paper introduces 2 types of levitated motors, each of which uses a combination of a rotary motor and a magnetic bearing. These motors are suitable for use in artificial blood pumps because they are small in size and can replace contact components. The radial type levitated motor has the merit of being small in size and capable of controlling the 2 degrees of freedom in the x and y directions. The axial type motor controls only one degree of freedom in the z direction. This paper also introduces the theoretical background of the functions of the motor and magnetic bearing. Experimental results of tests of the proposed motor show a great potential for its application in rotary blood pumps.

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“…Reference [8] reports on a novel internal PM-type of SBM which demonstrates very good bearing capacity relative to surface-mounted PM SBMs.…”

Section: Introductionmentioning

confidence: 99%

“…Okada et al [7], [8] provided a general theory for self-bearing operation and radial position control in PM synchronous and induction-type motors based on the so-called principle, i.e., designs where the stator pole number is , being the rotor pole number. Reference [8] reports on a novel internal PM-type of SBM which demonstrates very good bearing capacity relative to surface-mounted PM SBMs.…”

Section: Introductionmentioning

confidence: 99%

Nonlinear Bearing Force and Torque Model for a Toothless Self-Bearing Servomotor

2008

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We report developments in the modeling of bearing force and torque for a toothless self-bearing servomotor (TSBS), a permanentmagnet synchronous machine that utilizes the Lorentz force for levitation and torque simultaneously. The contactless nature and toothless construction of the device results in smooth torque production, making the TSBS ideal for precision pointing and slewing applications. We present, for the first time, nonlinear analytical expressions for force and torque based on first principle modeling. The parameters are identified from system data using linear least squares. The resulting nonlinear model aligns very well with finite-element analysis predictions. This approach has advantages over previous modeling efforts, which were purely analytical and always yielded linearized force and torque expressions.

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Levitation and torque control of internal permanent magnet type bearingless motor

Cited by 73 publications

References 3 publications

Analytical model of radial forces considering mutual effects between torque and levitation current space vectors in 5-phase PM bearingless motors

Analytical model of radial forces considering mutual effects between torque and levitation current space vectors in 5-phase PM bearingless motors

Magnetically Levitated Motor for Rotary Blood Pumps

Nonlinear Bearing Force and Torque Model for a Toothless Self-Bearing Servomotor

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