Robust PID Controller Design for Active Magnetic Bearing

This paper presents a robust PID control scheme for a rigid rotor magnetic bearing system with five-axiscontrol system of actual test rig. The robust PID design method based on H¥ closed-loop gain shaping theory is developed and used in the active magnetic bearing. After discussing the design theory of the robust PID control system based on H¥ control theory, we obtained the PID parameter formulae. Next, we designed the robust PID control system. We tried the simulations of control system for the radial bearing and obtained good performances on simulations. We carried out experiments to verify the robustness based on robust control theory for the actual test rig. The start-up suspension displacement curve and the characteristic of disturbance rejection for lower frequency have been measured. We confirmed that the robust PID control scheme has excellent performances for disturbance rejection and robust performance with parameter variations in this test rig.