Optimum Design Methodology for Axially Polarized Multi-Ring Radial and Thrust Permanent Magnet Bearings

This article deals with the generalized procedure of designing and optimizing multi-ring radial and thrust permanent magnet bearings (PMBs) with an axial air gap for maximum force andstiffness per volume of the magnet. Initially, the procedure of determining optimized design variables inboth the configurations is presented using the MATLAB codes written for solving the three dimensional(3D) equations of force and stiffness in PMB having ‘n’ number of rings on the stator and rotor. Themaximized results of the forces in both radial and thrust multi-ring PMBs are validated with the valuesobtained using finite element analysis (FEA). Then, the correlation between the optimized parametersand the air gap is obtained, and curve fit equations for the same are proposed in terms of stator outerdiameter. Further, curve fit equations establishing the relationship between the maximized bearingfeatures, and the aspect ratio (L/D4) of the bearing are expressed for different values of air gap inboth the radial and thrust bearings. Finally, the generalized method of designing and optimizing themulti-ring PMB is demonstrated with a specific application. A designer can use the presented curvefit equations for optimizing design variables and calculating maximized bearing features in multi-ringradial and thrust PMBs easily just by knowing the bearing features for a single ring pair.