Abstract:Wireless power transfer (WPT) has been a research focus in recent decades. Based on magnetically-coupled resonant WPT (MCR-WPT), this paper made a comparison of two basic structures in MCR-WPT: the two-coil structure and the four-coil structure. Their equivalent circuits were built. To illuminate the difference between these two structures, the input impedance, the transfer efficiency, and the load matching were studied and tested by experimental results. The conclusion is drawn that without reducing the transfer efficiency, the addition of the source coil and the load coil in the four-coil structure makes it easier to match the source and the load than the two-coil structure.
[1] Kurs A, Karalis A, Moffatt R, et al. Wireless power transfer via strongly coupled magnetic resonances[J]. Science, 2007, 317(5834): 83-86. [2] Sample A, Meyer D, Smith J. Analysis, experimental results, and range adaptation of magnetically coupled resonators for wireless power transfer[J]. IEEE Transactions on Industrial Electronics, 2011, 58(2): 544-554. [3] Duong T, Lee J. Experimental results of high- efficiency resonant coupling wireless power transfer using a variable coupling method[J]. IEEE Microwave and Wireless Components Letters, 2011, 21(8): 442-444. [4] Lee W, Son W, Oh K, et al. Contactless energy transfer systems using antiparallel resonant loops[J]. IEEE Transactions on Industrial Electronics, 2013, 60(1): 350-359. [5] Kusaka K, Itoh J. Experimental verification of rectifiers with SiC/GaN for wireless power transfer using a magnetic resonance coupling[C]. Proc. Power Electronics and Drive Systems, 2011: 1094-1099. [6] Lee S, Lorenz R. Development and validation of model for 95%-efficiency 220W wireless power transfer over a 30-cm air gap[J]. IEEE Transactions on Industry Applications, 2011, 47(6): 2495-2504.