Speed Controller Design for Electric Drives Based on Decoupling Two-Degree-of-Freedom Control Structure

In the speed control of electrical machine servo systems, the two-degree-of-freedom (2DOF) control has attracted considerable attention due to its ability to optimize both the system's reference tracking performance and disturbance suppression performance. However, the existing 2DOF control structures have the shortcoming that the coupling relationship of the reference tracking performance regulation and disturbance suppression performance regulation results in cumbersome controller design and parameter tuning. To address the shortcoming, this article proposes a new decoupling 2DOF control structure consisting of the control law and the observer. First, to demonstrate the advantages of the proposed control structure in reducing the complexity of controller design and parameter tuning, the design process and performance comparison of the speed controllers based on conventional control structures and the proposed control structure are presented in detail. Furthermore, to illustrate the advantages of the proposed structure in increasing the flexibility of controller design, four decoupling 2DOF speed controllers are designed for four typical speed servo conditions. Subsequently, the system stability is proved by analyzing the distribution of the characteristic roots, and parameter tuning guidelines for the four decoupling 2DOF speed controllers are provided. Finally, The experimental results verify the effectiveness of the proposed method.