Abstract Electrically excited synchronous machines (EESM) has the advantages of low dependence on rare earth permanent magnet materials, controllable excitation field and wide speed regulation range, and has a good application prospect in electric vehicles. However, the traditional EESM's brush-slip ring structure caused friction loss, increased maintenance costs, and reduced reliability. Therefore, brushless excitation has become an urgent requirement and a critical issue to be solved for EESM applications. Inductively coupled brushless excitation technology can effectively reduce friction losses and maintenance costs. Currently, mainstream brushless excitation methods include exciter type, harmonic excitation type, and wireless power transfer type. Wireless power transfer excitation can be divided into inductive coupling and capacitive coupling types. Inductive coupling excitation has a simple structure and high transmission efficiency, making it promising for applications. However, the usage of brushless excitation technology will bring a new challenges. The excitation winding of brushless excitation system rotates with the rotor, and there is no direct electrical connection between the transmitting circuit and the receiving circuit, resulting in the acquisition of excitation current value facing technical challenges. To estimate the field current in similar scenarios has been the scope of some previous studies. The existing current estimation methods can achieve good results in their respective application fields, but there are some limitations and shortcomings, which need to be further developed. In view of this, an indirect excitation current estimation method based on reduced order dynamic phasor model is proposed for series-series compensation inductively coupled brushless excitation system, which has the characteristics of simple calculation, strong load adaptability and low hardware cost. The topology structure of excitation energy transmission circuit is designed. The equivalent circuit model of excitation system is established. In order to avoid the influence of load parameter disturbance, an indirect current estimation method is proposed by using the inductive coupling relation and the secondary side reflection voltage as the intermediate variable. A reduced order dynamic phasor estimation model is established to further improve the estimation accuracy of the indirect estimation method. Considering the harmonic effect of subside current, an improved method of variable waveform coefficient is proposed. Finally, the validity of the current estimation method is verified by simulation and experiment. The experimental results show that indirect estimation method has high robustness, the maximum relative estimation error is 4.7% under load variation. Compared with the steady-state estimation model, the reduced order dynamic phasor estimation model can maintain higher estimation accuracy when the load condition changes. Using approximately fitted variable waveform coefficientkαto modify the estimation model can effectively reduce the estimation error caused by secondary current harmonics. The proposed excitation current estimation method has a good effect in series-series inductively coupled excitation system. And only one current sensor is required, resulting in low hardware cost. However, the detailed analysis and accurate acquisition of waveform coefficients in the rectification model need further research. In addition, the indirect estimation idea and the dynamic phasor model can be used to estimate the current of more inductively coupled excitation systems with non-series-series topology with high accuracy and high robustness, and broaden the application range of the proposed current estimation method.
Fu Xinghe,Xia Hongwei,Xiong Jiaxin. Indirect Field Current Estimation Algorithm for Inductively Coupled Excitation Systems Based on Reduced-Order Dynamic Phasor Model[J]. Transactions of China Electrotechnical Society, 2023, 38(19): 5152-5163.
[1] Fallows D, Nuzzo S, Galea M.Exciterless wound-field medium-power synchronous machines: their history and future[J]. IEEE Industrial Electronics Magazine, 2022, 16(4): 44-51. [2] 寇佳宝, 高强, 滕咏哮, 等. 负载换流逆变器驱动电励磁同步电机无速度传感器模型预测控制方法[J]. 电工技术学报, 2021, 36(1): 68-76. Kou Jiabao, Gao Qiang, Teng Yongxiao, et al.Speed sensorless model predictive control for load commutated inverter-fed electrically excited synchronous motor[J]. Transactions of China Electrotechnical Society, 2021, 36(1): 68-76. [3] 付兴贺, 江政龙, 吕鸿飞, 等. 电励磁同步电机无刷励磁与转矩密度提升技术发展综述[J]. 电工技术学报, 2022, 37(7): 1689-1702. Fu Xinghe, Jiang Zhenglong, Lü Hongfei, et al.Review of the blushless excitation and torque density improvement in wound field synchronous motors[J]. Transactions of China Electrotechnical Society, 2022, 37(7): 1689-1702. [4] 卿晓东, 苏玉刚. 电场耦合无线电能传输技术综述[J]. 电工技术学报, 2021, 36(17): 3649-3663. Qing Xiaodong, Su Yugang.An overview of electric-filed coupling wireless power transfer technology[J]. Transactions of China Electrotechnical Society, 2021, 36(17): 3649-3663. [5] Dajaku G, Gerling D.Self-excited synchronous machine with high torque capability at zero speed[C]//2018 International Symposium on Power Electronics, Electrical Drives, Automation and Motion (SPEEDAM), Amalfi, Italy, 2018: 1165-1171. [6] Di Gioia A, Brown I P, Nie Yue, et al.Design and demonstration of a wound field synchronous machine for electric vehicle traction with brushless capacitive field excitation[J]. IEEE Transactions on Industry Applications, 2018, 54(2): 1390-1403. [7] Maier M, Parspour N.Operation of an electrical excited synchronous machine by contactless energy transfer to the rotor[J]. IEEE Transactions on Industry Applications, 2018, 54(4): 3217-3225. [8] Song Kai, Li Zhenjie, Jiang Jinhai, et al.Constant Current/voltage charging operation for series-series and series-parallel compensated wireless power transfer systems employing primary-side controller[J]. IEEE Transactions on Power Electronics, 2018, 33(9): 8065-8080. [9] Zaghrini C, Khoury G, Fadel M, et al.Minimum copper losses per torque optimization on electrically excited synchronous motors for electric vehicles applications[C]//2022 IEEE 20th International Power Electronics and Motion Control Conference (PEMC), Brasov, Romania, 2022: 661-666. [10] Stancu C, Ward T, Rahman K M, et al.Separately excited synchronous motor with rotary transformer for hybrid vehicle application[J]. IEEE Transactions on Industry Applications, 2018, 54(1): 223-232. [11] Jiao Ningfei, Liu Weiguo, Zhang Zan, et al.Field Current estimation for wound-rotor synchronous starter-generator with asynchronous brushless exciters[J]. IEEE Transactions on Energy Conversion, 2017, 32(4): 1554-1561. [12] Yao Fei, An Quntao, Sun Lizhi, et al.Optimization design of stator harmonic windings in brushless synchronous machine excited with double-harmonic-windings[C]//2017 International Energy and Sustainability Conference (IESC), Farmingdale, NY, USA, 2017: 1-6. [13] Hagen S, Dai Jiejian, Brown I P, et al.Low-cost, printed circuit board construction, capacitively coupled excitation system for wound field synchronous machines[C]//2019 IEEE Energy Conversion Congress and Exposition (ECCE), Baltimore, MD, USA, 2019: 5358-5364. [14] Zhong Wenxing, Ron Hui S Y. Charging time control of wireless power transfer systems without using mutual coupling information and wireless communication system[J]. IEEE Transactions on Industrial Electronics, 2017, 64(1): 228-235. [15] Tang Junfei, Jiang Bowen, Boscaglia L, et al.Observations of field current and field winding temperature in electrically excited synchronous machines with brushless excitation[C]//2022 International Conference on Electrical Machines (ICEM), Valencia, Spain, 2022: 841-847. [16] Berweiler B, Ponick B.Current and average temperature calculation for electrically excited synchronous machines in case of contactless energy supply[C]//2020 International Conference on Electrical Machines (ICEM), Gothenburg, Sweden, 2020: 1730-1735. [17] Chen Fengwei, Garnier H, Deng Qijun, et al.Control-oriented modeling of wireless power transfer systems with phase-shift control[J]. IEEE Transactions on Power Electronics, 2020, 35(2): 2119-2134. [18] Li Hongchang, Fang Jingyang, Tang Yi.Dynamic phasor-based reduced-order models of wireless power transfer systems[J]. IEEE Transactions on Power Electronics, 2019, 34(11): 11361-11370. [19] Tang Junfei, Liu Yujing, Lundberg S.Estimation algorithm for current and temperature of field winding in electrically excited synchronous machines with high-frequency brushless exciters[J]. IEEE Transactions on Power Electronics, 2021, 36(3): 3512-3523. [20] Kang Jinsong, Liu Yusong, Sun Liangrong.A primary-side control method of wireless power transfer for motor electric excitation[C]//2019 14th IEEE Conference on Industrial Electronics and Applications (ICIEA), Xi'an, China, 2019: 2423-2428. [21] 郑广策, 赵凯, 王浩宇, 等. 基于LCC-S补偿网络的无线充电系统小信号模型[J]. 电工技术学报, 2022, 37(21): 5369-5376. Zheng Guangce, Zhao Kai, Wang Haoyu, et al.Small-signal model for inductive power transfer systems using LCC-S compensation[J]. Transactions of China Electrotechnical Society, 2022, 37(21): 5369-5376. [22] Kang Jinsong, Liu Yusong, Sun Liangrong, et al.A reduced-order model for wirelessly excited machine based on linear approximation[J]. IEEE Transactions on Power Electronics, 2021, 36(11): 12389-12399. [23] Cao Pengju, Tang Yunyu, Zhu Fan, et al.An IPT system with constant current and constant voltage output features for EV charging[C]//IECON 2018-44th Annual Conference of the IEEE Industrial Electronics Society, Washington, DC, USA, 2018: 4775-4780. [24] 赵进国, 赵晋斌, 张俊伟, 等. 无线电能传输系统中有源阻抗匹配网络断续电流模式最大效率跟踪研究[J]. 电工技术学报, 2022, 37(1): 24-35. Zhao Jinguo, Zhao Jinbin, Zhang Junwei, et al.Maximum efficiency tracking study of active impedance matching network discontinous current mode in wireless power transfer system[J]. Transactions of China Electrotechnical Society, 2022, 37(1): 24-35.
2023, Vol. 38 
