Hybrid SOGI-FLL-LUT Sensorless PMSM Drive With Back-EMF Distortion Elimination

There is growing demand for robust sensorless control of Permanent Magnet Synchronous Motors (PMSMs), but conventional methods using Phase Locked Loops (PLLs) are computationally intensive and offer limited back-Electromotive Force (back-EMF) distortion compensation across wide speed ranges. To address this issue, this paper focuses on an optimized second-order general integrator (SOGI) with frequency lock loop (FLL) and look-up table (LUT) to observe back-EMF for sensorless control of PMSMs. The observer is based on a reduced-order back-EMF model that utilizes the voltage equation in <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">α</i>-axis and relies on a single SOGI to estimate the fundamental back-EMF component in both <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">α</i> and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">β</i> axes. This paper further derives the SOGI-FLL observer model to guide parameter design and implementation and evaluates robustness through sensitivity analysis. Harmonic distortion in back-EMF is addressed using a time-domain numerical LUT. The observer is implemented in discrete time on a dSPACE PMSM drive platform. Simulations and experiments under various conditions confirm its effectiveness over two conventional sensorless algorithms.