Enhanced Position Estimation Accuracy Based on Improved Super-Twisting Observer and Position Compensation PLL for PMSM Sensorless Control

In order to enhance the position estimation accuracy of sensorless control of permanent magnet synchronous motor (PMSM), this brief proposes an improved super-twisting observer (STO) combined with a novel position compensation phase-locked loop (PLL) scheme. In this sensorless technology, the improved STO is designed using linear and nonlinear correction terms to achieve precise reconstruction of back electrimotive force (EMF) and finite-time convergence. With the back-EMF accurately estimated, the position compensation PLL is presented to alleviate the position error introduced by the speed acceleration and deceleration ramps when extracting position and speed information. Ultimately, the experimental comparisons on a 0.75-kW PMSM drive reveal that the proposed sensorless scheme has superior position estimation accuracy in both speed dynamics and steady state compared with the conventional schemes.