Anti-Windup Control of Active Magnetic Bearings Subject to Voltage Saturation

Active magnetic bearings (AMBs) have been widely applied in industrial rotating machinery. Power amplifier as an essential actuator of the AMB faces the limitation of DC bus voltage. A simple approach is to increase the voltage to a high value, but it has to deal with large current ripples and a low resolution. Other than the ordinary method, this paper addresses to the anti-windup control of AMB that aims to eliminate the adverse effect of the voltage saturation. The antiwindup algorithm is an addition to the nominal linear controller. And only when the saturation occurs is it activated. The stability is guaranteed by the procedure of calculating the linear matrix inequality (LMI) form of the regional Lyapunov stability. Simulation test is done to verify the proposed controller. Finally in the motor drive experiment, the axial AMB equipped in the prototype supports the thrust force. With the load changes, the performance of the anti-windup controller is demonstrated.