A Simultaneous Wireless Information and Power Transfer System With Independent Channel for Information Transfer

Reliable communication between the primary and the secondary side is a challenge for simultaneous wireless information and power transfer (SWIPT) system. Considering many factors, such as cost, device size, and transmission efficiency, the SWIPT system transferring multiple frequencies with a single inductive link is an effective scheme to integrate reverse data communication. However, those SWIPT systems change power transfer frequency or power carrier amplitude while transferring information, then information cannot be transmitted when the inverter does not work, which reduces the reliability of communication. To solve this problem, this paper proposes an idea of establishing an independent information transfer channel, the power and information transmits at different frequencies. The information transmitted in the reverse direction no longer flows through the primary side inverter. It is guided to an independent channel after being transmitted to the primary side through the common inductive link. Its equivalent circuit model is provided to analyze the transfer gain, power transfer performance, and the relationship between the information coupling circuit and information transfer characteristics. Finally, a SWIPT prototype is built to validate the proposed SWIPT system.