Magnetic Coupled Resonant Wireless Power Transfer With Metamaterials

Magnetic coupling resonant wireless power transmission technology has received an extensive attention on these days, which is expected to be the most promising technology for applications of power transmission field in the future. However, to improve the transmission efficiency of the system is still the key point of the research. Metamaterials are artificial materials which can achieve the secondary focusing of electromagnetic waves due to the negative coefficient of refraction. In this article, metamaterials were applied in the MCR-WPT systems. The improvement of the transmission efficiency was realized by binding the divergence magnetic induction lines between the resonance inductor owing to the negative coefficient of refractionThe working principle and system constitution of the magnetic coupling resonant wireless power transmission system as well as the electromagnetic characteristics theory of metamaterials were introduced firstly.Secondly, the model of the magnetic coupling resonant wireless power transmission system based on coupled mode theory and equivalent circuit theory was studied, then the equivalence of the two theories were discussed. Next, the expressions of output power and transmission efficiency of the four different topologies were derived by using the equivalent circuit theory, and the transmission characteristics of the series-series topology typed magnetic coupling resonant wireless power transmission system were studied. Furthermore, according to the derived output power and transmission efficiency expressions, the six impacts of transmission distance, resonant frequency, load, input voltage, coupling coefficient and quality factor on the output power and transmission efficiency were discussed.Finally, the model of magnetic coupling resonant wireless power transmission system was designed by HFSS, and the six variables of the system model were analyzed separately to get the optimal system parameters. Then a metamaterial structure which has an equivalent permeability ? =-1 at the frequency 9.599 MHz was presented and the effect of seven variables of metamaterial structure on the tuning characteristics are discussed. When the transmission distance is 400 mm, a 4?4 metamaterial plate was placed in the midpoint of the two resonant coil, and the transmission efficiency was raised to 30.83% from 18.96%, but the operation frequency was shifted. After optimization, the system with metamaterial plate obtained its maximum transmission efficiency of 34.16% at 9.56 MHz. Additionally, metamaterial plate and magnetic coupling resonant wireless power transmission system has been fabricated. The luminance of the bulb was compared under the condition that whether there is the metamaterial plate or not. The results shown that the bulb is brighter when the metamaterial plate was applied in the system.In conclusion, the transmission efficiency can be improved by using the metamaterial plate in the Magnetic coupling resonant wireless power transmission system.