Modeling and Analysis of Coupling Performance of Dynamic Stiffness Models for a Novel Combined Radial‐Axial Hybrid Magnetic Bearing

Abstract

The combined radial-axial magnetic bearing (CRAMB) with permanent magnet creating bias flux can reduce the size, cost, and mass and save energy of the magnetic bearing. The CRAMB have three-degree-of-freedom control ability, so its structure and magnetic circuits are more complicated compared to those of the axial magnetic bearing (AMB) or radial magnetic bearing (RMB). And the eddy currents have a fundamental impact on the dynamic performance of the CRAMB. The dynamic stiffness model and its cross coupling problems between different degrees of freedom affected for the CRAMB are proposed in this paper. The dynamic current stiffness and the dynamic displacement stiffness models of the CRAMB are deduced by using the method of equivalent magnetic circuit including eddy current effect, but the dynamic current stiffness of the RMB unit is approximately equal to its static current stiffness. The analytical results of an example show that the bandwidth of the dynamic current stiffness of the AMB unit and the dynamic displacement stiffness of the CRAMB is affected by the time-varying control currents or air gap, respectively. And the dynamic current stiffness and the dynamic displacement stiffness between the AMB unit and the RMB unit are decoupled due to few coupling coefficients.

Analysis and design method of a combined radial–axial magnetic bearing based on asymmetric factor

“…Since the CRAMB with a conical rotor was proposed in the 1990s [14], more and more literature focus on the research of the CRAMB [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29], mainly including coupling properties, dynamic modelling, magnetic field analysis, and novel structures. Based on the comparison with that of separated MBs, it was found that the coupling problem of the CRAMB is more serious than that of separated MBs [17].…”

“…Based on the comparison with that of separated MBs, it was found that the coupling problem of the CRAMB is more serious than that of separated MBs [17]. In [18][19][20][21], further studies on the coupling problem of the CRAMB have been conducted. The force coupling of a CRAMB was designed and analysed with a coupling factor [18].…”

“…The force coupling of a CRAMB was designed and analysed with a coupling factor [18]. In [19,20], the coupling effects on stiffness were analysed based on the dynamic stiffness models for a CRAMB. In [21], the decoupling method for CRAMB was proposed.…”

Dynamical Model of an Electromagnet using Cauer Ladder Network Representation of Eddy-current Fields

“…One is analytical modeling by using the equivalent magnetic circuit, which is preferred frequently (2) (3) because of its ease. The other is the identification of the transfer function of the electromagnet by using the FE analyses (4) .…”

Integrated radial/thrust magnetic bearing without thrust disk for a high‐speed driving system

“…In order to reduce the size and power consumption, and increase the axial load capacity simultaneously, the segregated radial laminated rotor core and solid thrust disk are proposed ( Fig. 1b) [22][23][24][25], the permanent magnet forms a cylindrical magnet sandwiched between a radial stator core and thrust stator core. A 3-DOF MB with a cylindrical rotor is designed [26,27], but the bearing tends to be bulky for large axial load.…”