Multi-Frequency Multi-Amplitude Superposition Modulation Method With Phase Shift Optimization for Single Inverter of Wireless Power Transfer System

In wireless charging devices, different wireless charging standards have caused charging incompatibility, and the utilization rate of the DC voltage at the transmitter is not high, which brings challenges to the application of wireless charging. To solve these two problems, this paper proposes a multi-frequency multi-amplitude (MFMA) superimposition modulation method. This method superimposes multiple frequency signals, and then compares the synthesized signal with a high-frequency triangular carrier to output a square wave voltage signal containing information such as the frequency and amplitude of the pre-output signal. Furthermore, a phase-shifting optimization algorithm is proposed, i.e., based on the proposed MFMA superimposition modulation method, the utilization rate of the DC voltage of the system is improved by reasonably adjusting the initial phase of each frequency. Simulation and experimental results show that the proposed method can output at least four frequencies simultaneously by using a single inverter, effectively reducing the volume of the transmitter, and being compatible with the frequency range of several charging standards. The proposed phase-shifting optimization has a significant effect on improving the utilization of DC voltage with an increase of 44.88%.