New Model of Radial Force Determination in Bearingless Motor

Abstract

This paper proposes to determine the radial forces in bearingless permanent magnet motor topology. We consider normal and tangential components of the magnetic field in the air gap. Their harmonic components and their evolution versus current and rotor position are considered. This allows establishing the semianalytical expressions of the radial forces considering different field sources. Their precision has been verified using a full finite element model and statistic analysis. The advantage of this semianalytical model lies in the swiftness of the different force components evaluation and consequently the reduction of CPU time.Index Terms-Bearingless permanent magnet (PM) motor, CPU time reduction, normal and tangential components of the magnetic field, radial force, semianalytical method, spectral analysis.

Radial force control for triple three-phase sectored SPM machines. Part II: Open winding fault tolerant control

“…Instead, to control the space vectors 2 and 4, and so the radial force, it is needed to analyze (14) and (16), which also depend on the 1 st , 5 th and 7 th space vectors. By (7) it is possible to evaluate all the current space vectors by M i and N i .…”

“…Furthermore, the radial force can be still controlled to a reference value, allowing the possibility to release the bearings from the rotor weight or other sources of force. The radial force control is based on the multi space vector approach, as in [9], rather than an equivalent magnetic circuit or a semi-analytical FE deduction, as in [5] and [10]- [14]. This paper is the second part of a work on the radial force control for triple three-phase sectored SPM machines.…”

Permanent magnet bearingless motors: Modelling, design and drive

“…In the case of the studied machine, takes three values: = 1 ∶ 2-pole source or winding ( = 1) on the stator = 2 ∶ 4-pole source or winding ( = 2) on the stator = 3 ∶ 2-pole magnets ( = 1) on the rotor The use of the definition of levitating forces (1) and this representation of normal and tangential flux density components allows us to express the force components and along the axes and in the form (a sum of different elementary forces generated by the interactions of successive ranks flux density harmonics a sum of different contributions of many harmonic interactions of successive ranks [14].…”

Experimental verification of an angle-sensorless control scheme for bearingless permanent magnet machines

“…The torque and bearing force calculation is based on the analysis of the magnetic flux density in the airgap, similar to the analysis presented by Laptre et al (2015). A FEM program was used to obtain the magnetic flux density around the rotor.…”