Inverse system decoupling control of electric spindle system supported by AC AMB

A dynamic decoupling control approach based on inverse system theory is developed for the electric spindle system supported by 5 degree-of-freedom (DOF) AC active magnetic bearings(AMB), which is multi-variable, nonlinear and strong coupling system. The state equations of the 5-DOF AC AMB are set up based on the configuration of 5-DOF AC AMB being introduced and mathematical models of axial and radial suspension forces being given. The reversibility of the system of 5-DOF AC AMB is analyzed, the state feedback algorithm based on a-th order inverse system method is deduced, and the original nonlinear coupled system is decoupled into pseudo-linear system. The linear quadranic optimum control theory is applied to synthesize the pseudo-linear system, and the system of simulation was set up based on MATLAB. The simulation experiments have shown that this decoupling control strategy can realize dynamic decoupling control among 5 degrees of freedom of the electric spindle system, the rotor can be suspended steadily and the system has good dynamic and static performance.