Cascaded Extended State Observer-Based Speed Controller Design of PMSM Considering Variable Control Gain and Uncertain Disturbance

Aiming at the problems of control gain mismatch and disturbance rejection in permanent magnet synchronous motor control system, this article proposes a variable control gain linear active disturbance rejection controller (VG-LADRC) with strong disturbance rejection ability and control gain adaptive function. This controller adopts a cascaded extended state observer. ESO1 is used to jointly estimate the system control gain and external disturbance, and ESO2 further compensates the residual disturbance on this basis, thus realizing hierarchical processing and coordinated suppression of disturbance observation. To enhance the adaptability of the controller to the change of control gain, this article designs a control gain adaptive law based on error feedback and integrates the motor dynamic information to construct an adaptive factor. Thus, the controller can improve the control gain convergence speed through multidimensional state perception and enhance its robustness under complex working conditions. Theoretical analysis shows that the VG-LADRC has excellent disturbance suppression performance in the range of low-frequency to medium–high frequency and exhibits strong robustness to control gain mismatch. Finally, dynamic tests are carried out to verify the control performance and engineering applicability of the proposed method.