Improvement in the design calculations of multi-ring permanent magnet thrust bearing

This article presents the design and optimization of multi-ring permanent magnet thrust bearing (PMTB) with an axial air gap between successive axial stacks. Larger air gap due to the inclusion of conductive materials needs to be critically analysed in permanent magnet bearings with eddy current damper. High conductivity materials can be filled in an axial air gap instead of a radial air gap to increase the required amount of damping. Three-dimensional (3D) mathematical model for load-carrying capacity for the said configuration is presented using the Coulombain model. The significance of an axial air gap between successive ring pairs in the configuration concerning maximization in the bearing characteristics is presented. Variables such as the number of axial stacks, an axial air gap between the successive rings, an inside radius of rotor ring magnets, and an inside radius of stator ring magnets are optimized at different air gap values for maximizing the load-carrying capacity and stiffness. A significant increase in the values of bearing characteristics is observed in the optimized configuration as compared to bearing with a single permanent magnet ring pair. Optimized PMTB with comparable load carrying capacity and stiffness values can be used to replace conventional bearings used in high-speed applications to improve system efficiency.