Investigation of magnetic field by the Hall sensors embedded into magnetic bearing poles

A typical eight poles heteropolar active radial magnetic bearing configuration, consisting of Hall sensors embedded in the poles, is a research target. The active magnetic bearing operates without a safety bearing, and therefore identification was carried out in the maximum range of rotor displacement. The magnetic field was investigated experimentally using digital twin simulations developed in COMSOL Multiphysics software. The conducted research showed nonlinear dependencies of the magnetic flux density measured in the pole pieces as a function of the current, position, and orientation of the rotor. Typically used formulas that describe the relationships between force, magnetic flux density, current, and distance have been shown so that they are not to be used for arbitrary bearing configurations, rotor positions, and orientations due to simplifying assumptions.