Power transfer limits and optimal operation frequency in induction power transfer systems incorporating high-frequency effects

Wireless power transfer systems based on magnetic induction are usually modeled using the magneto-quasi-static approximation, and by neglecting skin effects and radiation losses. These assumptions imply that the extracted power can grow unlimitedly by increasing frequency or coil size. To bridge these gaps, this work proposes general expressions for the actual received power. In this work, we analyze an induction power transfer system, comprised of serially-compensated transmitter and receiver coils. The output power and efficiency as a function of the input power are derived. A primary result is that the receiver's output power and the system efficiency are inherently limited by radiation losses at high frequencies and impaired by skin and proximity effects at medium frequencies. Our proposed approach provides a design tool for estimating the maximal power that can be delivered through a given system, and the corresponding optimal operation frequency.