Modeling and Mechanism Analysis for Sensorless Control of Permanent Magnet Synchronous Motor Drive System with the Effects of Demagnetization Faults
Wang Huimin1,2, Guo Gaoli1, Zuo Yun1, Wan Sibo3, Ge Xinglai1
1. Key Laboratory of Magnetic Suspension Technology and Maglev Vehicle Ministry of Education Southwest Jiaotong University Chengdu 610031 China; 2. State Key Laboratory of Heavy-Duty and Express High-Power Electric Locomotive Zhuzhou 410075 China; 3. Tangshan Institute of Southwest Jiaotong University Tangshan 063000 China
Abstract：Due to the mismatch between high-power operation and the limited capacity for heat dissipation, as well as the long-term effects of uneven operating conditions, the issue of demagnetization faults is regarded as one of the main challenges for the reliable operation of sensorless-controlled permanent magnet synchronous motor (PMSM) drive systems. Many models fail to elaborate on the effects of different demagnetization faults on the performance of sensorless-controlled PMSM drives. This paper proposes a model that considers the impact of demagnetization faults. Firstly, a finite element model (FEM) of PMSM under healthy conditions is established. When the PMSM is operating under healthy conditions, the magnetic induction lines and flux density distributions of the PMSM are symmetric. Moreover, the no-load air-gap flux density is also symmetric in this case. With the fast Fourier transform (FFT) analysis results, there are several main harmonic components (e.g., 5th-and 7th-order harmonic components) in the no-load air-gap flux density. Then, the FEM of PMSM with demagnetization faults is further established. Regarding the uniform demagnetization fault, all permanent magnets exhibit the same degree of demagnetization. The uniform demagnetization fault is simulated by adjusting the residual magnetization curve of every permanent magnet. Then, the PMSM with uniform demagnetization faults still shows the symmetric magnetic induction lines and flux density distributions. Moreover, the no-load air-gap flux density in this case exhibits the same behavior when the PMSM is operating under healthy conditions. The situation changes completely when the PMSM is operating under non-uniform demagnetization faults. Different types of non-uniform demagnetization faults, such as single permanent-magnet, two adjacent permanent-magnet, two alternating permanent-magnet, and two relative permanent-magnet pole demagnetization faults, are carefully analyzed. When the PMSM experiences non-uniform demagnetization faults, the asymmetric magnetic induction lines and flux density distributions are observed. The no-load air-gap flux density undergoes obvious distortions. That is, with the single permanent-magnet and two adjacent permanent-magnet pole demagnetization faults, in addition to the integer-order harmonic components (e.g., 5th-and 7th-order harmonic components), the non-integer-order harmonic components (e.g., 1/4-, 2/4-, 3/4-, 5/4-, 6/4-, and 7/4-th order harmonic components) appear in the no-load air-gap flux density. The no-load air-gap flux density suffers from the odd non-integer-order harmonic components (e.g., 1/4-, 3/4-, 5/4-, and 7/4-th order harmonic components) under a two alternating permanent-magnet poles demagnetization fault. At the same time, the even non-integer-order harmonic components (e.g., 2/4-and 6/4-th order harmonic components) appear in the no-load air-gap flux density under a two relative permanent-magnet poles demagnetization fault. Based on the mathematical model of the PMSM under healthy conditions, the permanent magnet flux is described under uniform and non-uniform demagnetization faults. Moreover, by combining the position estimation scheme based on the sliding mode observer (SMO) and phase-locked loop (PLL) with a vector-controlled PMSM drive system, an analytical model of sensorless-controlled PMSM drives with demagnetization faults is obtained. The effects of demagnetization faults on the performance of sensorless-controlled PMSM drives are elaborated. Finally, hardware-in-the-loop (HIL) tests are carried out. When the uniform demagnetization faults occur, sensorless-controlled PMSM drives still operate symmetrically. Moreover, within an acceptable range of demagnetization degree, the uniform demagnetization fault shows a minor impact on the performance of sensorless-controlled PMSM drives. The speed and position estimations are negligibly affected, and the phase current increases to maintain the motor's torque performance. In contrast, the sensorless-controlled PMSM drives face issues of obvious current distortions and large torque ripples under non-uniform demagnetization faults. Consequently, the degraded speed and position estimations are observed. Additionally, with the increase of demagnetization degree, the effects of demagnetization fault on the performance of the sensorless-controlled PMSM drives expand. Under different demagnetization faults, sensorless-controlled PMSM drives exhibit varying behaviors.
王惠民, 郭高利, 左运, 万斯波, 葛兴来. 永磁同步电机无位置传感器控制系统退磁故障建模及影响机理分析[J]. 电工技术学报, 2025, 40(18): 5877-5891.
Wang Huimin, Guo Gaoli, Zuo Yun, Wan Sibo, Ge Xinglai. Modeling and Mechanism Analysis for Sensorless Control of Permanent Magnet Synchronous Motor Drive System with the Effects of Demagnetization Faults. Transactions of China Electrotechnical Society, 2025, 40(18): 5877-5891.
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