Basic Analysis of Two-Coils Structure Based on Magnetically-Coupled Resonant Technology for SWIPT Application ∗

The Magnetically-coupled resonant (MCR) technology is exploited in this paper to realize Synchronous wireless information and power transfer (SWIPT) func- tion, which means that the power carriers also transmit information. The circuit structure of SWIPT system is ana- lyzed and the existence of two optimal frequencies in power efficiency under small resistance circumstance is proved. The physical parameters having influences on the two op- timal frequencies are discussed, such as the distance be- tween coils, impedance characteristics of coils and loads. These results provide a way to increase the bandwidth of MCR technology, while maintaining high power efficiency to realize SWIPT function. Simulations and experimental results are presented to verify the feasibility of the pro- posed system and obtained theoretical expressions.