Abstract：The synchronous reluctance motor (SynRM) exhibits significant saturation and coupling phenomena, leading to noticeable position observation errors in sensorless control. To achieve high-precision sensorless control of SynRM at zero and low speeds, it is crucial to fully consider the motor's saturation and coupling characteristics, which are primarily reflected in nonlinear inductance changes and the coupling terms in the inductance matrix. Online inductance identification can acquire the motor's saturation and coupling characteristics, which are essential for optimizing sensorless control. This paper proposes a position observation method for synchronous reluctance motor at zero and low speeds, considering saturation and coupling characteristics. First, the influence of motor saturation and coupling characteristics on the high-frequency effective flux linkage observer in zero and low-speed sensorless control is analyzed. Then, a virtual axis equivalent impedance model is constructed to simplify the SynRM model by decoupling the axes. An online identification method for the decoupled axis model parameters is proposed to describe the saturation and coupling characteristics of the SynRM, thereby eliminating position observation errors. Finally, combined with the results of online identification, motor saturation and coupling error compensation are implemented in the sensorless control of the SynRM at zero and low speeds. A 3 kW SynRM test platform was set up. The experimental results demonstrate that the proposed method enables high-precision sensorless control of SynRM at zero and low speeds. Full-load acceleration tests were conducted to verify the effectiveness of the high-frequency effective flux observer in the SynRM, where the speed variation remained stable and the steady-state error was close to zero. Additionally, zero and low speeds at 150 r/min were selected. Under constant speed conditions, load step change tests were conducted to verify the accuracy of the high-frequency effective flux observer. Experimental results show that correcting and compensating the high-frequency effective flux observer with the identified motor saturation and coupling characteristics can significantly improve the sensorless observation accuracy of the SynRM at zero and low speeds. The steady-state position observation error at zero speed was reduced by 85.7%, 76.7%, and 80.8% under no-load, half-load, and full-load conditions. At low speeds, the steady-state position observation error was reduced by 98.2%, 73.4%, and 80.4% under no-load, half-load, and full-load conditions. The conclusions can be drawn. (1) SynRMs exhibit significant variations in saturation and coupling characteristics, which cannot be ignored in the design of sensorless control at zero and low speeds. (2) The proposed method simplifies the high-frequency effective flux observer, ensuring stable speed and position output without using a low-pass filter. (3) The proposed method reduces the steady-state error of the observed angle and improves the observation accuracy for sensorless control of the SynRM at zero and low speeds.
王奇维, 赖芷璇, 李斌兴, 王高林, 徐殿国. 考虑饱和及耦合特性的同步磁阻电机零低速运行位置观测方法[J]. 电工技术学报, 2025, 40(24): 7958-7968.
Wang Qiwei, Lai Zhixuan, Li Binxing, Wang Gaolin, Xu Dianguo. Position Observation Method for Synchronous Reluctance Motor at Zero and Low Speeds Considering Saturation and Coupling Characteristics. Transactions of China Electrotechnical Society, 2025, 40(24): 7958-7968.
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