Abstract：The compound tubular permanent magnet linear actuator (CTPMLA) integrates a passive damping system with a tubular permanent magnet linear synchronous motor. It provides a continuous thrust of 1 076 N and a maximum damping force of 2 754 N, suitable for vehicles' active suspension systems. The primary structure comprises a solid iron core and solid aluminum rings in slot opening, which has induced eddy currents during the movement of the mover and generates additional damping force. However, the increase in eddy current losses leads to significant temperature rises due to the limited heat dissipation capacity of the tubular design. High temperatures can adversely affect the output performance of the CTPMLA, pose risks of permanent magnet demagnetization, and accelerate the aging of the winding insulation. Therefore, it is crucial to investigate the rise in temperature of the CTPMLA. The copper losses in the windings are the predominant loss in the electric state, reaching 164.26 W. The second loss is the eddy current losses of the aluminum rings, reaching 24.42 W, which significantly exceeds the losses in the stator core despite their small volume. For modeling convenience, regard the insulation varnish, air, and slot insulation within the stator model as a uniform insulating material and the copper as a homogeneous entity. The CTPMLA is divided into three sections based on heat flow paths. A thermal network model for individual slots is established to create a multi-node thermal network model for all sections. The Reynolds number is calculated for various surfaces to assess airflow patterns, facilitating the determination of convective heat transfer coefficients and thermal resistances. Then, an electromagnetic-thermal coupling calculation process is developed to explain the impact of temperature on material conductivity and air thermal parameters. The data is exchanged by a couple of inputs and outputs between the electromagnetic and thermal models, and the losses, convective thermal resistances, and gap thermal resistances are iteratively updated until temperature convergence is achieved. The temperature field of the CTPMLA is calculated via varying vehicle speeds and currents under electric and locked rotor states. Results indicate that the maximum value of the average winding temperature reaches 121.9℃ in the electric state, while the maximum value of the average temperature of the permanent magnets is 81.58℃. At locked rotor states, the maximum value of average winding temperature is 108.5℃, while that of permanent magnets is 89.8℃. All temperatures are significantly below the limited temperature of 180℃ of insulating materials and permanent magnets. Finally, the comparison is carried out with a three-dimensional finite element temperature field model. The errors are 4% for the windings and 3.1% for the permanent magnets, which demonstrates the efficiency of the thermal network coupling model. Moreover, its computation time is only 10.9% of the finite element model. Based on the developed prototype, the temperature experiments of the locked rotor are carried out under natural and forced convection conditions. The error margin is less than 4%, verifying the effectiveness of the proposed thermal network coupling model.
冯云南,吴丽泽, 李焱鑫,卢琴芬. 复合圆筒型永磁直线作动器热网络模型与热性能研究[J]. 电工技术学报, 2025, 40(18): 5854-5865.
Feng Yunnan, Wu Lize, Li Yanxin, Lu Qinfen. Research on Thermal Network Model and Thermal Performance of Compound Tubular Permanent Magnet Linear Actuator. Transactions of China Electrotechnical Society, 2025, 40(18): 5854-5865.
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