Improved design and analysis of a radial magnetic bearing with paired‐pole or alternating‐pole configurations

There are some problems in the permanent magnetic circuit of the current permanent magnet biased magnetic bearings, such as small magnetic force, low magnetic flux density and lack of self-stabilization. To solve this problem, a new hybrid radial magnetic bearing structure has been proposed. The nonlinear model and linearization equation of the new hybrid radial magnetic bearing capacity has been established by current molecular method and virtual displacement theorem. It is found that the permanent magnetic bearing can achieve self-stabilization in the radial degrees of freedom and can reduce the total displacement of negative stiffness. The results show that the air gap flux density is greatly improved by the new hybrid magnetic bearing with Halbach array structure. Current stiffness and displacement rigidity is closely related to initial current and initial gap of the equilibrium position. Near the equilibrium position, current stiffness and displacement rigidity are linear relationship. With the increase of air gap, it remains a good linearity. While with the decrease of air gap, it presents nonlinear characteristics..

Download Full-text

Stiffness Measurement of Permanent Magnet Biased Radial Magnetic Bearing in MSFW

Journal of Dynamic Systems Measurement and Control ◽

10.1115/1.4030721 ◽

2015 ◽

Vol 137 (9) ◽

Cited By ~ 3

Author(s):

Sun Jinji ◽

Bai Guochang ◽

Yang Lei

Keyword(s):

Permanent Magnet ◽

Measurement Method ◽

Magnetic Circuit ◽

Magnetic Bearing ◽

Stiffness Measurement ◽

Stiffness Characteristics ◽

Radial Magnetic Bearing ◽

The Relationship ◽

Magnetic Center

To measure current stiffness and displacement stiffness of permanent magnet biased radial magnetic bearing, a new stiffness measurement method is proposed for magnetically suspended flywheel (MSFW). The detailed stiffness measurement method is proposed in this paper. At first, the suspension force and stiffness characteristics of the permanent magnet biased radial magnetic bearing are studied using magnetic circuit method and finite element method (FEM). Second, the detailed stiffness measurement method of permanent magnet biased radial magnetic bearing is proposed. It has two procedures, one is the determination of the magnetic center in radial magnetic bearing when the gravity of rotor is in the +x(+y) direction and −x(−y) direction, respectively, then the current stiffness can be obtained, and the other is the calculation of the displacement stiffness according to the relationship between rotor displacement and current. A prototyped MSFW with angular moments of 50 Nms is manufactured, and the proposed stiffness measurement method of permanent magnet biased radial magnetic bearing is verified by prototyped experiments.

Download Full-text