Self-Adaptive Intermediate Resonator in a 3-Coil Inductive Link for Power and Data Transmission

This brief presents an innovative approach that dynamically adapts the intermediate resonator to enable efficient transmission of power and data over the same inductive link. The proposed intermediate resonator presents a tuned and high-Q response during power transmission, promoting high efficiency in the link. However, when the data transmission begins, it automatically adjusts its response to enable proper communication. Two different approaches for modifying the resonator response during data transmission are tested: 1) dynamically reducing the quality factor, and 2) dynamically detuning the resonator. The proposed resonator is designed, implemented, and applied to an actual commercial system to demonstrate its effectiveness. The selected proof-of-concept system is a low-frequency RFID link, widely used for cattle identification. Detuning the resonator, instead of reducing its quality factor, during data transmission was demonstrated to achieve greater reading distances. Measurements results show that the proposed resonator increases the RFID reading distance by up to $\approx 300$ % (from 16 cm to 65 cm) compared to not using a resonator, and up to $\approx 50$ % (from 43 cm to 65 cm) compared to using a regular resonator without the proposed dynamic adaptation. Hence, this brief validates the concept of employing batteryless self-adaptive resonators in inductive power links.