An Improved Frequency-domain Method for the Fractional Order PI λ D µ Controller Optimal Design

Abstract An improved frequency-domain design method is proposed to design the fractional order PI λ D µ controller. Using this improved method, the parameters of the fractional order PI λ D µ controllers can be obtained immediately according to the model characteristics and design specifications. A proportional relation between the integral gain and derivative gain is built, while the derivative order is set to be equal to the integral order. The proportional coefficient between integral gain and derivative gain is studied and modeled based on priori knowledge and data fitting, and then the estimation model for the optimal proportional coefficient is built. The proposed tuning method is applied to design a fractional order PI λ D µ controller for a permanent magnet synchronous motor servo system. Motor speed control simulations are performed to verify the proposed method. Simulation results show that the obtained control system can achieve robustness and the optimized step response performance.