Decoupling control of 5 degrees of freedom AC hybrid magnetic bearings based on inverse system method

A decoupling control approach based on inverse system method is developed for an electro-spindle system suspended by 5 degrees of freedom AC hybrid magnetic bearings (HMBs), which is a multivariable, nonlinear, strong coupled system. Based on the introduction of AC HMB´s configuration, principle operation, and setting up mathematical equations of radial and axial suspension forces, the state equations of AC HMBs are set up. The analytical inverse system of the HMBs is obtained by analyzing the reversibility of the mathematical model. Then the inverse system compensates original system to pseudo linear system of linear transmission relationship. Finally, linear system theory is applied to these linearization subsystems to synthesize, and simulation is carried out. The theory research and simulation experiments show that the proposed control strategy can realize dynamic decoupling control among the 5 degrees of freedom of AC HMB electro-spindle, and the whole control system has good dynamic and static performance.