Power transfer efficiency (PTE) enhancement and electromagnetic interference (EMI) reduction method using a frequency selective repeater coil for loosely-coupled wireless power transfer system

Abstract

With the advent of the fourth industrial revolution, wireless power transfer technology is becoming increasingly important. However, one of the biggest limitations of current wireless power transfer technology is that it can not transmit power with high efficiency from long distance. Currently, the wireless charging system has enabled the market for wireless charging pads for short-range charging of low-power electronic devices such as smart phones. However, in the case of high-power electronic devices or electronic devices requiring long-range wireless charging, there is a limit. Also, when a wireless power transfer system is applied, electromagnetic interference problems arise. Electromagnetic interference causes malfunction of sensors. Various solutions have been studied and proposed over the years to overcome these problems. In this paper, we propose a repeater coil that can enhance high efficiency and reduce electromagnetic interference. Analytical equations were derived to analyze the power transfer efficiency and electromagnetic interference reduction rate at a specific resonant frequency of the repeater, and by simulation and measurement to verify this. Through the design and analysis equations presented in this study, it is expected that a repeater coil with a long - distance wireless power transfer system can be designed.