Auto-Tuning of Speed Controller for PMSM Using Nonlinear Dynamic Inversion Control

In this paper, a feedback control technique using nonlinear dynamic inversion control (NDIC) for the speed control of surface permanent magnet synchronous motors (PMSM) will be introduced. The speed control law using NDIC ensures the stability of the closed-loop control system of PMSMs once the motor parameters are measured properly, and the location of the closed-loop poles can be designed by any linear control method. After that, the linear quadratic regulator (LQR), which is widely used for optimal control design, is employed to determine the closed-loop poles of the control system. Combining the NDIC speed control law with the LQR pole placement method, the new method “NDICLQR” is developed for the speed control law of PMSMs. Since there will be only one parameter to be tuned in the NDICLQR method and a given cost function is minimized, the control system can be auto-tuned, which means that the user does not have to tune the independent control gains manually, as in the conventional field-oriented control (FOC).