High Frequency Resistance in Litz-Wire Planar Rectangular Solenoid Coils for Wireless Power Transfer
Deng Qijun1 Liu Jiangtao2 Chen Cheng1 Jiang Yan1 Zhou Hong1
1.Department of Automation Wuhan University Wuhan 430072 China; 2.School of Physics and Electrical Engineering Hubei University of Education Wuhan 430205 China
Abstract：The high frequency current is un-uniform in the wire due to external magnetic field. As a result, the conductive area of the wire is far smaller than its cross-section, and the excess resistance, namely the frequency-dependent resistance, is induced. The high frequency resistance is proportional to the square of the magnetic field the wire exposed to. The paper employees the Biot-Savart law to analyze the magnetic field distribution of the planar rectangular solenoid coils for evaluating the frequency-dependent resistance. The maximum quality factor of the coil and the corresponding optimal operation frequency are derivate based on the analyses of the field and resistance. A few coils are manufactured and their high frequency resistances are measured. The measurements show that the proposed method predicts the resistance under various frequencies and the optimal operation frequency precisely. Two coils, whose outer and inner dimensions are 460 mm×208 mm and 312 mm×64 mm, are employed to build a wireless power transfer system. Under the frequency slightly lower than the predicted optimal one, the system obtains the maximum DC-DC efficiency of 58.7% and receives 50 watts power at the distance of 500 mm.
邓其军,刘姜涛,陈诚,蒋燕,周洪. 应用于无线电能传输的Litz线平面矩形螺旋线圈高频电阻计算[J]. 电工技术学报, 2016, 31(11): 176-185.
Deng Qijun Liu Jiangtao Chen Cheng Jiang Yan Zhou Hong. High Frequency Resistance in Litz-Wire Planar Rectangular Solenoid Coils for Wireless Power Transfer. Transactions of China Electrotechnical Society, 2016, 31(11): 176-185.
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2016, Vol. 31 
