Observer-Based Unbalance Compensation in LQ-Control of AMBs

In this work, a model-based linear-quadratic controller with an optimal observer-based unbalance force rejection control for variable speed magnetically suspended rotors is presented. The unbalance force rejection control is considered in two variants. In the first one, the unbalance forces are canceled and the system can maintain an accurate reference rotor position. This variant results in low measured vibration amplitudes. In the second one, the magnetic force vibrations are canceled and the rotor spins about its principal axis of inertia within the bearing clearance. The control currents and energy usage are minimal, and the vibrations are slightly decreased. Both cases are designed as a periodic disturbance observer. Simulations for the variable speed and an experimental evaluation at the constant speed are presented.