Abstract：Electromagnetic couplers are the core components of wireless power transfer (WPT), and their operating temperature determines the stability and service life of the system operation. Therefore, accurately estimating the coil winding and magnetic core losses of high-frequency electromagnetic couplers and studying the temperature rise distribution of electromagnetic couplers under normal modes are crucial for the heat dissipation design of underwater autonomous vehicles and improving the reliability of WPT systems. To address these issues, this article takes the rotary electromagnetic coupler with strong resistance to radial offset as the research object and establishes a three-dimensional electromagnetic thermal field simulation model that considers the influence of insulation induced turn spacing and temperature on material properties, achieving accurate calculation of hot spot temperature. Firstly, theoretical analysis is conducted on the temperature rise of the electromagnetic coupler, which involves calculating the loss of the electromagnetic coupler, and then loading the loss as a heat source into the heat flow field to obtain the temperature distribution of the electromagnetic coupler; Secondly, based on the temperature rise principle of electromagnetic couplers and strictly following the temperature rise calculation process, the finite element Ansys Maxwell simulation software is used to solve the electromagnetic loss and hot spot distribution. In the simulation software, the first step is to calculate coil losses and magnetic core losses.Then, using the transient electromagnetic field heat flow field bidirectional indirect coupling method, a three-dimensional electromagnetic field simulation model is established. Finally, the electromagnetic loss calculation results are coupled as loads into the heat flux field and corresponding relationships are established to obtain the hot spot distribution of the rotating electromagnetic coupler. The simulation results show that the magnetic field distribution of the electromagnetic coupler is basically symmetrical from top to bottom, and the magnetic field intensity gradually decreases along the center position of the magnetic core towards the end. The maximum magnetic density is located on the surface of the magnetic core close to the geometric center of the secondary coil. The average loss density distribution of the electromagnetic coupler has the same characteristics as the magnetic induction intensity distribution. At 20 ℃, the average loss errors of the primary and secondary coils within one cycle were obtained through theoretical analysis and finite element simulation, which were 2.9% and 3.4%. The experimental results show that the deviation between the parameters measured by the LCRand the numerical values in simulation is less than 10%. The thermocouple multi-channel thermometer records the temperature of the system when it reaches steady state at 20 ℃. The high-temperature area is located at the top of the secondary coil, and the deviation between the simulated temperature of the hot spot and the measured value is less than 6%, verifying the rationality of the modeling method. The following conclusions can be drawn through experimental analysis:(1) The average loss density of the magnetic core of the rotating electromagnetic coupler is positively correlated with the distribution of magnetic induction intensity; (2) The relative position of the coil, flow velocity, and convective heat transfer coefficient all have an impact on the operating temperature of the system. At the same time, due to the influence of the nested structure, local overheating will occur under the high temperature conduction of the coil, resulting in the severe temperature rise area of the rotating electromagnetic coupling concentrated in the middle of the LCT; (3) In order to simulate the temperature rise distribution of rotary electromagnetic couplers more accurately, in addition to considering the turn spacing caused by insulation, the temperature effect of material properties should also be considered.
程志远, 宋晓逸, 吴晓婷, 贵子航, 李东东. 无线充电系统旋转式电磁耦合器损耗计算及热点温度研究[J]. 电工技术学报, 2024, 39(7): 1932-1942.
Cheng Zhiyuan, Song Xiaoyi, WuXiaoting, Gui Zihang, Li Dongdong. Loss Calculation and Hot Spot Temperature Research of Rotary Electromagnetic Coupler in Wireless Charging System. Transactions of China Electrotechnical Society, 2024, 39(7): 1932-1942.
[1] Zeng Yingqin. Lu Conghui, Liu Renzhe, et al.Liu, Wireless power and data transfer system using multidirectional magnetic coupler for swarm AUVs[J]. IEEE Transactions on Power Electronics, 2023, 38(2): 1440-1444. [2] 闫争超, 胡谦宇, 赵晨旭, 等. 水下航行器感应式无线电能传输技术研究综述[J/OL]. 中国电机工程学报, 2022: 1-16[2023-02-15]. https://kns.cnki.net/kns8/defaultresult/index. Yan Zhengchao, Hu Qianyu, Zhao Chenxu, et al. Summary of research on induction radio energy transmission technology for underwater vehicles[J/OL]. Proceedings of the CSEE, 2022: 1-16[2023-02-15] https://kns.cnki.net/kns8/defaultresult/index [3] Yan Zhengchao, Zhang Yiming, Zhang Kehan, et al.Underwater wireless power transfer system with a curly coil structure for AUVs[J]. IET Power Electronics, 2019, 12(10): 2559-2565. [4] Qiao Kangheng, Sun Pan, Rong Enguo, et al.Anti-misalignment and lightweight magnetic coupler with H‐shaped receiver structure for AUV wireless power transfer[J]. IET Power Electronics, 2022, 15(16): 1843-1857. [5] Gerasimov V A,Komlev A V, Filozhenko A Y. improving the quality of the underwater robot’s contactless battery charging system[C]//Journal of Physics: Conference Series, 2021, 2096(1): 012107-. DOI:10.1088/1742-6596/2096/1/012107. [6] Chae D J, Kim Y S.Analysis for electrical and thermal hazard in kW-class wireless power transmission environment[C]//2018 IEEE PELS Workshop on Emerging Technologies: Wireless Power Transfer (Wow), Montreal, QC, Canada, 2018. DOI:10.1109/WoW.2018.8450930. [7] Hwang K, Chung S, Yoon U, et al.Thermal analysis for temperature robust wireless power transfer systems[C]//2013 IEEE Wireless Power Transfer (WPT), Perugia, Italy, 2013.DOI:10.1109/WPT.2013.6556879. [8] Li Yang, Zhao Jingtai, Yang Qingxin, et al.A novel coil with high misalignment tolerance for wireless power transfer[J]. IEEE Transactions on Magnetics, 2019, 55(6): 1-4. [9] Campi T, Cruciani S, De Santis V, et al.EMF safety and thermal aspects in a pacemaker equipped with a wireless power transfer system working at low frequency[J]. IEEE Transactions on Microwave Theory and Techniques, 2016, 64(2): 375-382. [10] 陈庆彬, 范峰, 汪金帅, 等. 无线电能传输磁耦合系统Litz线圈交流电阻精确评估方法[J]. 电工技术学报, 2022, 37(24): 6294-6305. Chen Qingbin, Fan Feng, Wang Jinshuai, et al.Accurate evaluation method for AC resistance of Litz coil of radio energy transmission magnetic coupling system[J].Transactions of China Electrotechnical Society, 2022, 37(24): 6294-6305. [11] 张献, 韩大稳, 沙琳, 等. 一种共享磁通多耦合模式的无线电能传输系统抗偏移方法[J]. 电工技术学报, 2022, 37(21): 5359-5368. Zhang Xian, Han Dawen, Sha Lin, et al.An anti-offset method for radio energy transmission system with shared magnetic flux multi-coupling mode[J] Transactions of China Electrotechnical Society, 2022, 37(21): 5359-5368. [12] 赵蒙蒙, 李岩松, 丰江波, 等. 轴式松耦合变压器的热行为特性及影响因素[J]. 电测与仪表, 2019, 56(7): 22-29. Zhao Mengmeng, Li Yansong, Feng Jiangbo, et al.Thermal behavior characteristics and influence factors of shaft-type loosely coupled transformer[J]. Electrical Measurement and Instrumentation, 2019, 56(7): 22-29. [13] Wang Shuo, Dorrell David G.Loss analysis of circular wireless EV charging coupler[J]. IEEE Transactions on Magnetics, 2014, 50(11): 1-4. [14] Liang Ce,Yang Guang, Yuan Feng, et al.Modeling and analysis of thermal characteristics of magnetic coupler for wireless electric vehicle charging system[J]. IEEE Access, 2020, 8: 173177-173185. [15] 毛行奎, 陈为. 开关电源高频功率平面变压器热设计研究[J]. 电工电能新技术, 2007, 26(4): 21-25. Mao Xingkui, Chen Wei.Research on thermal design of high frequency power plane transformer for switching power supply[J]. New Electrical Energy Technology, 2007, 26(4): 21-25. [16] Zhu Tianxin, Feng Panshang, Li Xuekun, et al.The study of the effect of magnetic flux concentrator to the induction heating system using coupled electromagnetic-thermal simulation model[C]//International Conference on Mechanical and Automation Engineering, Jiujiang, China,2013: 123-127. [17] Kalra G R, Pearce M G S, Kim S, et al. A power loss measurement technique for inductive power transfer magnetic couplers[J]. IEEE Journal of Emerging and Selected Topics in Industrial Electronics, 2020, 1(2): 113-122. [18] Tiemann M, Saifo M, Clemens M, et al.Magnetic and thermal coupled field analysis of wireless charging systems for electric vehicles[J]. IEEE Transactions on Magnetics, 2019, 55(6): 1-4. [19] Kazimierczuk M.High-frequency magnetic components[M]. 2nd ed. Chichester, UK: John Wiley & Sons, 2014. [20] Liu Jiangtao, Deng Qijun, Czarkowski D, et al.Frequency optimization for inductive power transfer based on AC resistance evaluation in Litz-wire coil[J]. IEEE Transactions on Power Electronics, 2019, 34(3): 2355-2363. [21] 程志远, 陈坤, 李东东, 等. 旋转式无线充电系统偏移特性研究[J]. 电工技术学报, 2021, 36(22): 4648-4657. Cheng Zhiyuan, Chen Kun, Li Dongdong, et al.Research on the offset characteristics of rotary wireless charging system[J]. Transactions of China Electrotechnical Society, 2021, 36(22): 4648-4657. [22] 李永建, 闫鑫笑, 张长庚, 等. 基于磁-热-流耦合模型的变压器损耗计算和热点预测[J]. 电工技术学报, 2020, 35(21): 4483-4491. Li Yongjian, Yan Xinxiao, Zhang Changgeng, et al.Transformer loss calculation and hot spot prediction based on magnetic-thermal-current coupling model[J]. Transactions of China Electrotechnical Society, 2020, 35(21): 4483-4491.
2024, Vol. 39 
