Analysis and Design of Active Disturbance Rejection Current Controller for Sensorless PMSM Drives

This paper proposes a novel control strategy for sensorless Permanent Magnet Synchronous Motor (PMSM) drives that combines a Sliding Mode Current Controller (SMCC) with an Extended State Observer (ESO) that acts as an active disturbance rejection (ADR) technique. The integrated design enhances robustness against electrical parameter variations and inverter nonlinearities, which are particularly critical at low operating speeds. Theoretical contributions include a rigorous Lyapunov-based stability analysis of the closed-loop system that explicitly incorporates the effect of the observer, particularly angle estimation errors, on system dynamics. In addition, a comprehensive sensitivity analysis with respect to operating-speed range and controller bandwidth is conducted, providing a practical methodology for gain and bandwidth tuning under step changes and parameter variations. Experimental validation on a 600 W PMSM test bench demonstrates that the proposed scheme significantly improves current tracking and torque stability compared to conventional PI control and standalone SMCC, especially under low- and medium-speed conditions.