A new improved method for computation of radial stiffness of permanent magnet bearings

The new method for the computation of the radial stiffness is based on the perturbative treatment of the deviation from the cylindrical symmetry of the magnetic field due to the small displacements of the rotor. It turns out that the partial differential equations of the vector potential are 2D and can be easily solved by means of appropriately adapted FEM programs. The present method is more general than the exact Coulomb integral method which can be applied only for force calculation in bearings without iron parts and is more exact and needs less computation effort than the method based on Cartesian development of the system.<>