Control of Permanent Magnet Synchronous Motor System Using MIMO Nonlinear Observer‐Based Controller

Abstract: In this paper, the control of permanent magnet synchronous motors has been conducted. The models of these motors are nonlinear and have two voltage inputs in the d – q coordinates, as well as two outputs: speed and current along the d ‐axis. Additionally, the load torque can be assumed as an undesired disturbance input. Therefore, in this paper, a nonlinear MIMO combined method based on an observer has been utilized for controlling permanent magnet synchronous motors. For this purpose, employing an extended state observer, the load torque, assumed as uncertainty, is estimated, and then, a nonlinear MIMO controller is employed to design the control input vector. To further enhance performance, a sliding mode–based observer is developed that not only estimates the load torque but also its derivative, enabling more accurate disturbance compensation. Moreover, a smooth sliding mode control law is adopted to completely eliminate chattering, which is a major drawback of conventional sliding mode control. In addition, employing a nonlinear MIMO sliding mode control structure provides better coordination between multiple inputs and outputs, resulting in improved robustness and control accuracy compared to conventional single‐input designs. In this configuration, the stability of the closed‐loop system composed of the MIMO controller, observer, and motor dynamics has been proven using the Lyapunov method. The proposed combined method offers the advantages of nonlinearity, resistance against uncertainties, and smooth control design. These features have been demonstrated analytically as well as through computer simulations.