Sun Jinji

Stiffness Measurement of Permanent Magnet Biased Radial Magnetic Bearing in MSFW

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.

Research on Configuration of Stator Core Stacks in Magnetic Bearing

The performance of magnetic bearing is determined the characteristics of magnetic materials, which is affected on the configuration of stator core stacks because of different stress under manufacturing process. The experimental results are shown that stator core stacks with reeling condition will lead to large current ripple in magnetic bearings coils, and then the power loss will be increased dramatically. The improved stator core stacks configuration is designed, that is to say, the stator core stacks is manufacturing with lamination condition. It can effectively reduce current ripple in magnetic bearings coils and the power loss of magnetic bearings because of its little stress. Then, the magnetic characteristics of two types of stator core stacks in magnetic bearing have been measured using magnetic materials measurement equipment to verify the correctness of the design.