Resonance and EMI in vertical multi-coupled coils for wireless power transfer (WPT) system

Wireless power transfer (WPT) using magnetic resonance could provide much convenience and so there has been much commercial interests on WPT recently. In the near future, WPT technology is expected to be applied to various electronic devices with transceiver coils for WPT. The coils in different electronic devices for WPT, then, could cause interference on each other. These environments could make a resonance peak for maximum power to divide into several peaks, and have an effect on transferred power and electromagnetic interference (EMI). Therefore, it is needed to measure and analyze various cases for different number of coils in WPT systems. In this paper, we have measured a resonance in vertical multi-coupled coils in the case of tight magnetic coupling. And we have analyzed the transferred power with respect to resonances of vertical multi-coupled coils. We also have measured EMI in vertical multi-coupled coils and analyzed EMI in frequency domain with respect to resonances of vertical multi-coupled coils for WPT systems.