Enhanced Analysis and Design Method of Dual-Band Coil Module for Near-Field Wireless Power Transfer Systems

A multi-band wireless power transfer (WPT) will be one of the important WPT research trends in the future. This work presents a single-coil dual-band WPT coil module as an example in the multi-band WPT applications. It can transfer more power than a single-band WPT can do within the electromagnetic field constraints. Moreover, one of its channels can be used to provide a higher data communication rate than that of a single-band WPT. Different from a multi-coil multi-band WPT, no unwanted cross coupling exists in this dual-band coil module because it uses only one coil for power coupling. An analytical process of the dual-band coil design guideline is presented. We can improve coil power transfer efficiency in the weakly coupling region and avoid frequency splitting in the strongly coupling region by selecting appropriate coil parameters as presented. The experimental results are in good agreement with the coil module analysis. Therefore, a flexible dual-band WPT coil module is obtained in this work.