Efficiency Improvement of SIMO WPT Using Capacity Control in addition to Load Control

When providing simultaneous wireless power transfer from one supply source to multiple receivers, i.e., single-input multiple-output (SIMO), there are many more control requirements than when there is one power supply going to one receiver, i.e., single-input single-output (SISO). Therefore, in this study, we focus on the minimal configuration of the SIMO WPT, i.e., a two receiver WPT, and propose a power receiving circuit where not only the load resistance but the series-connected capacitor can be controlled. The theoretical and conditional formulas for meeting the specified power ratio are derived , and the method for searching the device parameters to achieve the maximum efficiency are discussed. In addition, from the simulations, we compared the proposed method with a conventional method using only the load resistance control, and demonstrated the potential of achieving higher efficiency in respect with the combination of the coupling coefficients.