Analysis and Mitigation of Coupling-Dependent Data Flipping in Wireless Power and Data Transfer System.

Load shift keying (LSK) has been widely used in a wireless power and data transfer (WPDT) system, owing to its low cost and power consumption. It was discovered that the demodulated data can flip when the coupling coefficient ($k$) between the transmitter (TX) and receiver (RX) coils becomes less than a critical value ($k_{\mathrm {DF}}$) in a system with four basic compensation topologies (series–series, series–parallel, parallel–series, and parallel–parallel). This problem is called coupling-dependent data flipping (CDDF). Even more seriously, the transferred data cannot be recovered when $k$ equals $k_{\mathrm {DF}}$. On the basis of a comprehensive circuit analysis of CDDF, a universal method applicable to all four compensation topologies was proposed. By monitoring the current through the TX coil rather than its voltage for data demodulation, CDDF can be avoided. Furthermore, a WPDT system was implemented in which the voltage information of the load resistance ($R_{\mathrm {Load}}$) was transferred to the TX side to control the source voltage for load power ($P_{\mathrm {Load}}$) regulation. Using the conventional method, CDDF along with its corresponding $k_{\mathrm {DF}}$ (0.35) was verified. On the other hand, using the proposed method, the data was successfully transferred even when $k$ is less than or equal to $k_{\mathrm {DF}}$. By a correct data transfer, $P_{\mathrm {Load}}$ has been successfully regulated at around 1.1 W with a high system efficiency of up to 60% under the variation in $k$ from 0.09 to 0.45. [ABSTRACT FROM AUTHOR]