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Aiming at the fully coupled problem of steady state and dynamic performance of a PI controller with one degree of freedom, two kinds of two DOF PI controllers were designed based on the setpoint filter structure and the setpoint feed-forward structure, and the design method of compensation link was introduced.On this basis, a variable structure two-degree-of-freedom PI controller was designed with reference to the idea of variable gain PI controller.Finally, the simulation results show that the controller can not only simplify the process of setting control parameters, but also take into account the steady-state performance, dynamic performance and anti-jamming performance of the system, and realize the function of output fast, no overshoot, no error tracking input signal changes.

Aiming at the poor performance of IP control system in tracking continuously varying input signals, a variable structure PI controller was proposed, which can eliminate overshoot of step response and track continuously varying input signals without error. The controller performs as an IP controller for step input signals and a PI controller for continuously changing input signals. Firstly, the control performance defects of traditional IP controller were analyzed, and then the structure of variable structure PI controller was built. Finally, the simulation results show that the VSPI and IP control systems have the same control effect when the step signal is input. Compared with PI control system, the VSPI and IP control systems not only have no overshoot but also have better response stability. When the input is a continuous sinusoidal signal, VSPI and PI can track the input signal almost without error, and the control effect is obviously better than IP control. The anti-jamming performance of the system is inversely proportional to the bandwidth value, but has nothing to do with the control mode.