The Asymmetrical Equivalent Circuit Model for Segment-Powered Linear Induction Motor Based on Static End Effect
Ji Xiang1, Xu Jin2, Han Zhengqing2, Li Mingke2
1. 91216 Troops Huludao 125100 China; 2. National Key Laboratory for Vessel Integrated Power System Technology Naval University of Engineering Wuhan 430033 China
Abstract：With the linear motor theory and the maturity of high power density electric energy conversion technology, the linear motor has been widely used in rail transit, mine elevators, linear elevators, logistics transmission, punching machines, and other fields. The linear induction motor used in the field of high-speed propulsion needs to accelerate the load to a predetermined speed within a short distance, generally adopting a long stator structure. At the same time, the motor stator adopts a segmented power supply method to improve the efficiency and power factors and reduce the capacity requirements. Due to the unenergized stator core at both ends of the stator, there is a large stray magnetic field at both ends, much stronger than the stray magnetic field at the end of the ordinary single-segment linear motor. Hence, the static end effect becomes the main factor affecting the performance of the motor. The static end effect is manifested as the asymmetric three-phase impedance of the motor, which can affect the motor’s electromagnetic characteristics, operation efficiency, and dynamics control. This paper proposes an equivalent circuit model using the symmetric component method. Based on the expression of the pulse air gap magnetic field in the positive-, negative-and zero-sequence current of the piecewise fed linear induction motor, the lumped parameter complex inductance is derived, and the asymmetric T-type equivalent circuit model of the motor is established. The port voltage equation of the motor at any supply current can be obtained. A parameter identification method of the asymmetric equivalent circuit model is proposed because it is inconvenient to carry out the no-load test. According to the stall test, the port voltage and current under different frequencies in the operating frequency range are obtained, and the key parameters are identified using the least square method. The proposed asymmetric equivalent circuit model is verified by comparing the current waveform calculated by the equivalent circuit model and identification parameters with the test current. The experimental results show that the current amplitude and phase considering static end effects are in good agreement with the experimental current, better reflecting the asymmetric characteristics of the motor. However, the current deviates from the actual value without considering static end effects. The thrust calculated considering static edge effects can better reflect the changes in electromagnetic force in the low-frequency range. As the frequency increases, the influence of harmonic current and lateral edge effects increases, and the actual value is biased to the calculated value.
冀相, 许金, 韩正清, 李明珂. 基于静态边端效应的分段供电双边直线感应电机不对称等效电路模型[J]. 电工技术学报, 2025, 40(18): 5845-5853.
Ji Xiang, Xu Jin, Han Zhengqing, Li Mingke. The Asymmetrical Equivalent Circuit Model for Segment-Powered Linear Induction Motor Based on Static End Effect. Transactions of China Electrotechnical Society, 2025, 40(18): 5845-5853.
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2025, Vol. 40 
