Synchronous power and signal transmission method for inductive wireless power transmission system by modifying compensation capacitance

Abstract

To synchronize the power forward transmission and signal reverse transmission of inductive wireless power transmission (IWPT) system, a signal reverse transmission method by modifying the compensation capacitance is proposed. Firstly, an equivalent circuit of signal reverse transmission circuit was established for the four basic compensation topologies of IWPT system, the relationship between the secondary-side compensation capacitance and the primary-side input impedance was analyzed. The analysis results indicate that the variable-capacitance method is more suitable for topology structures where the secondary coil and compensation capacitor are connected in series. Then, a variable-capacitance modulation method by detecting the phase angle of the input impedance of the primary side for series-series (SS) systems was proposed, and its impact on power transmission was analyzed. To improve the readability of the data at the receiving side, a data frame structure was designed. This structure is easy to identify the starting bit of the data, making it unnecessary for the signal demodulation at the receiving side to start working before the signal modulation at the sending side. Finally, the effectiveness of the method was verified by simulation and experiment. The results show that this method can successfully modulate and demodulate signals when the load and mutual inductance change. The data readability is improved, and the method has little impact on power transmission.