A Novel Cascaded Linear–Nonlinear Active Disturbance Rejection Controller Strategy for Sensorless Permanent Magnet Synchronous Motor

To enhance the permanent magnet synchronous motor (PMSM) performance in terms of disturbance rejection and speed tracking under load variations, parameter perturbations, and other uncertainties, this paper proposes a sensorless speed control method based on a cascaded linear-nonlinear active disturbance rejection controller (CL-NLADRC). Firstly, a third-order cascaded linear-nonlinear extended state observer (ESO) is employed to estimate the rotor speed, phase, and total disturbances. While the front-stage linear ESO ensures system stability in the face of large disturbances, the back-stage nonlinear ESO the residual disturbance from the linear ESO, improving tracking accuracy and disturbance rejection through nonlinear mechanisms. Second, to enhance the system’s dynamic properties, a speed controller built on the linear state error feedback control rate (LSEFCR) is designed. The Routh-Hurwitz criterion is used to assess the stability of the controller, and the frequency domain performance of the system is investigated in terms of noise suppression and disturbance rejection. Finally, experimental comparisons using conventional PLL, linear active disturbance rejection control (LADRC), cascaded linear active disturbance rejection control (CLADRC), and CL-NLADRC are conducted on the PMSM system to verify the superiority of the proposed technique.