Variable current stiffness mathematical modeling method for six-pole radial-axial hybrid magnetic bearing

The invention discloses a variable current stiffness mathematical modeling method of a six-pole radial-axial hybrid magnetic bearing, which is applied to the field of accurate modeling of nonlinearity of suspension force of a magnetic suspension bearing. The method solves the problem that the force-current rigidity of the magnetic suspension bearing in a suspension force mathematical model under rotor eccentricity is influenced by rotor eccentricity displacement, so that the magnetic bearing mathematical model is difficult to accurately express the nonlinearity. On the basis of establishing a six-pole-radial-axial hybrid magnetic bearing suspension force linearization mathematical model by using an equivalent magnetic circuit method, a summary analysis method for a suspension force-current stiffness change rule during rotor displacement change is designed; a proper fitting function is selected to fit the relation between the suspension force-current stiffness and rotor eccentricity, the obtained fitting funct