An Anti-windup Design Method for Internal Model Control Based on H∞ Optimization

Performance and stability of internal model control can deeply deteriorate when plant control input is subject to saturation. Study is made on the reason why two-degree-of-freedom internal model control has anti-windup characteristics. From this consideration, a new modified three-degree-of-freedom internal model control scheme is proposed. This method can realize the decoupling of anti-windup, reference tracing and disturbance rejection. Anti-windup controller synthesis based on H_infin optimization theory. Small gain theorem guarantees the global stability. Simulation results show the method has better ability of anti-windup and disturbance rejection