Wireless power transfer via magnetic resonant coupling is an advanced technique to realize high transmitting efficiency with several meters of transmitting displacement. Therefore, this technique is quite suitable for wireless charging of electric vehicles. However, if there is any foreign metal presented between the transmitting and receiving coils, it is difficult to maintain high transmitting efficiency. This main reason is the foreign metal cause mismatching of resonant frequency of the transmission coils. The most important, the foreign metal will be heated by eddy currents induced by the transmission coils so that not only the transmitting efficiency is lowered but also the temperature of the foreign metal will get very high rapidly and perhaps cause involuntarily dangerous.
- IA-04-0020 (220K)