High frequency capacitive coupling wireless power transfer using glass dielectric layers

Wireless power transfer (WPT) technologies are magnetic and capacitive coupling methods, typically. The capacitive coupling WPT has many advantages such as simple structure, low electromagnetic interference and transferring with metal barrier. However, it is hard to reduce the impedance of coupling capacitor for sufficient received output voltage in the capacitive coupling WPT. Therefore, in this paper, 6.78MHz high frequency operation and glass dielectric layers can make an impedance of the coupling capacitance small and it is possible to transfer power easily. In addition, less switching loss can be obtained for high efficiency and low electromagnetic interference (EMI) noise with the LLC resonant tank. It results in high efficiency and sufficient output power. Features of the proposed converter are verified with a 4.2W prototype for charging a mobile device.