A Novel Flux Estimator Using α-β Orthogonality Drift Elimination for High Performance Full-Speed-Range Sensorless Control

With no need for position sensors, sensorless control makes permanent magnet synchronous motor (PMSM) more compact, more economical, and easier to manufacture. Due to the advantages of no model limitation and low noise level, flux estimator is a promising method of sensorless control, while the drift caused by pure integrator limits its performance so hitherto it is not used in precision motor control. In this paper, a new flux estimator with drift elimination capability is designed to achieve high-accuracy flux estimation. The proposed drift eliminator using the orthogonality of α- and β-axis can estimate the drift in variable situations with high dynamic performance. Theoretical interpretation is given while comparative simulations and experiments consistently show that the proposed estimator can eliminate the flux drift phenomenon efficiently. Sensorless control experiments are also conducted on a permanent magnet linear synchronous motor (PMLSM), where the position estimation error (PEE) can be lower than 50 µm. The results certify that the proposed estimator can be used in high-precision sensorless control, both for constant speed and variable speed trajectories.