Research on sensorless control technology for UAV electric propulsion PMSM in zero/low-speed range using improved Luenberger observer

In sensorless control of permanent magnet synchronous motors (PMSMs) for unmanned aerial vehicle (UAV) electric propulsion, conventional high-frequency voltage injection methods based on phase-locked loops (PLLs) are susceptible to strong electromagnetic interference and noise, which significantly reduce the accuracy of rotor position estimation under high-noise operating conditions. To address this limitation, this paper proposes a rotor position estimation method based on an improved Luenberger observer (LO). The method builds upon high-frequency square-wave voltage injection and incorporates direct observation of position errors, enabling high-precision rotor position tracking in the zero- and low-speed regions. Simulation results demonstrate that, under both noise-free and noise-disturbed conditions, the proposed method significantly reduces rotor position estimation errors and enhances system dynamic response compared with the conventional PLL method. The proposed approach provides an effective solution for achieving high-precision control at low speeds in UAV electric propulsion systems.