Reverse Transmission Technology of Power and Signal in SPWM Controlled Wireless Power Transfer System Based on Harmonic Application

Aiming at the pressing need for not only forward power transmission but also reverse signal transmission for condition monitoring and closed-loop control in Inductively Coupled Power Transfer (ICPT) systems applied in special fields such as robot joints, bioengineering, and underwater detection, this paper proposes a simultaneous wireless power and reverse signal transmission ICPT system based on SPWM composite modulated wave control. Applying high-frequency harmonics as the reverse communication medium, the system superimposes power modulation waves and signal modulation waves of different frequencies. By driving the high-frequency inverter circuit through an SPWM controller, it achieves efficient forward power transmission without the need for additional physical communication coils. Meanwhile, by controlling the switching of the parallel modulation resistor on the secondary side, amplitude variation is constructed in the high-frequency harmonic component of the primary current based on the reflection impedance principle. 2ASK (Binary Amplitude Shift Keying) and non-coherent demodulation techniques are then employed to accurately extract the reverse signal. Simulation results demonstrate that the system can stably achieve synchronous bidirectional interaction of power and signal at a data rate of 10 kbit/s. Furthermore, the harmonic injection has minimal impact on power quality, and bidirectional crosstalk is well-controlled within a reasonable range.