Control of Inverse System of Rotor Radial Magnetic Suspension of Bearingless Flux-Switching Permanent Magnet Machines Based on Decoupling of Least Squares Support Vector Machines
Lin Jialong, Zhou Yangzhong, Chen Dongyuan, Liang Tongwei
Key Laboratory of Energy Digitalization Fuzhou University Fuzhou 350108 China
Abstract：The unique stator structure of bearingless flux-switching permanent magnet motors (BFSPMM) generates the suspension force of the rotor influenced by the coupling effects of self-inductance of the suspension winding, mutual inductance between the suspension winding and the torque winding, and rotor angle. However, previous suspension force modeling schemes have not fully considered the influence of the coupled electromagnetic force, resulting in low accuracy of the suspension force model. The inverse system decoupling control method relies on a high-precision mathematical model. Therefore, establishing a more accurate suspension force model is the key to achieving high-performance decoupling control of the motor suspension. This paper proposes an inverse system control strategy based on least squares support vector machine (LSSVM). The model accuracy is improved to fit and compensate for the coupled electromagnetic force, and the performance of the suspension inverse system control is enhanced. Based on the rotor motion equation, the coupling effect of the gyroscopic effect force and the coupled electromagnetic force in the suspension force on the rotor radial displacement of BFSPMM is analyzed. Random current excitations within a limited range are applied to the finite element model of BFSPMM to obtain the operating data set under different rotor position angles and radial displacements. The operating data set trains LSSVM to obtain the LSSVM prediction model of the coupled electromagnetic force. During the motor operation, the operating data is sent to the LSSVM prediction model to obtain the real-time predicted value of the coupled electromagnetic force. It is compensated to the original system through the force-current relationship to decouple initially. Finally, the inverse system method decouples the nonlinearity of the gyroscopic effect coupling part of the suspension system, achieving complete decoupling of the BFSPMM rotor suspension system. The simulation results show that the predicted value of the coupled electromagnetic force by LSSVM is close to that of the finite element simulation, with high prediction accuracy. Suppose the rated operating condition of the motor with a speed of 1 500 r/min and a torque of 4 N·m. The results show that during the start-up of suspension, the rotor radial displacement overshoot of the proposed control strategy is smaller and the system stability is better than that of the PID control. Similarly, when a sudden change occurs in the suspended load, the rotor under the PID control strategy generates a large amplitude fluctuation in the radial displacement, with a maximum value of 0.023 mm. In contrast, the rotor displacement of the proposed control strategy is almost unaffected. The experimental results show that the radial displacement of the proposed control strategy under the rated condition is controlled within 0.054 mm, only 45.0% of that of the PID control. Under different speed and torque conditions, the rotor radial displacement can also be controlled within 0.076 mm. Additionally, when a sudden disturbance is applied to the x-axis, the radial displacement in the x-axis direction generates a disturbance of 0.15 mm, while the y-axis is almost unaffected. Likewise, when a sudden disturbance is applied to the y-axis, the radial displacement in the y-axis direction generates a disturbance of 0.13 mm, while the x-axis is almost unaffected. The proposed control strategy achieves decoupling control of the suspension system. The conclusions are as follows. (1) LSSVM can approximate the coupled electromagnetic force in the suspension force, improve the accuracy of the model, and enhance the decoupling control effect of the suspension inverse system. (2) The proposed control strategy significantly improves the rotor radial displacement ripple and has good dynamic decoupling performance.
林佳泷, 周扬忠, 陈东远, 梁彤伟. 基于最小二乘支持向量机解耦的无轴承磁通切换电机转子径向磁悬浮逆系统控制[J]. 电工技术学报, 2025, 40(14): 4534-4546.
Lin Jialong, Zhou Yangzhong, Chen Dongyuan, Liang Tongwei. Control of Inverse System of Rotor Radial Magnetic Suspension of Bearingless Flux-Switching Permanent Magnet Machines Based on Decoupling of Least Squares Support Vector Machines. Transactions of China Electrotechnical Society, 2025, 40(14): 4534-4546.
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2025, Vol. 40 
