Low-Speed Sensorless Control Based on Improved Finite Position Set-Observer for Interior Permanent Magnet Synchronous Motors

This article proposes a finite position set observer based on a mathematical model considering cross-coupling factors for sensorless control of interior permanent magnet synchronous motors at low speeds. The objective is to address the limitations of conventional high-frequency (HF) signal injection methods, which suffer from reduced accuracy and practical implementation challenges in rotor position estimation. To enhance accuracy, the proposed method incorporates cross-coupling factors of inductances into the motor modeling and state equation derivation processes. This inclusion improves the precision of the obtained rotor position information. Furthermore, the cost function and iteration method of the position observer are redesigned to achieve faster convergence toward the optimal rotor position while minimizing computational complexity. To validate the effectiveness of the proposed approach, an experimental comparison is made with the conventional HF signal injection sensorless control method, demonstrating its superiority in terms of accuracy and feasibility.