Deign And Simulation Of Fractional Order Controllers For Fractional Order System

With the development of the fractional order calculus theory, many research scholars have attempted to apply the fractional order calculus theory to the actual system model and the actual system control, that is to say, the fractional order system model and the fractional order controller design are presented for the actual controlled model. In this dissertation, the fractional control strategy is presented for the fractional order plant in order to improve the dynamic performance of the fractional order control system.From the fractional calculus theory, main researches focus on factional order systems stability, fractional order controller design and fractional order operator discrete approximation method. Firstly, stability of fractional order systems is analyzed using nyquist criterion of fractional order system and logarithm frequency criterion of fractional order system. Secondly, the method of phase margin and gain margin is adopted for fractional order controller parameters tuning, and the fractional order proportional integral controller and the fractional order [proportional integral] controller are designed in the same index. Thirdly, Al-Alaoui+CFE approximation method and improved Oustaloup approximation method are used for discrete approximation of the two fractional order control systems, and comparison results show that the control systems based on improved Oustaloup approximation method offers a better dynamic performance. Finally, comparative simulation experiment of the two control systems are implemented by improved Oustaloup approximation method, and simulation results show that in the case of interference, FO[PI] controller which can significantly improve dynamic performance of the system will get better control effect, and validate that the proposed fractional control strategy for fractional order plant is effective.