Power Boosting of Strongly Coupled Wireless Power Transfer Systems by Aligning 1^st/3^rd Harmonic Frequencies With Splitting Frequencies

This letter proposes a novel power-boosting strategy for strongly coupled wireless power transfer system by aligning the first and third harmonic frequencies of the inverter switching node voltage with the lower and upper splitting frequencies, respectively. Within the parity-time symmetric region, the output power at splitting frequencies significantly exceeds that at the natural resonant frequency. Additionally, when the coupling coefficient k is larger than 0.8, the output power can be further enhanced by superimposing the first and third harmonic voltages of the inverter, all while maintaining high efficiency. Finally, experimental results demonstrate that the proposed strategy achieves an output power of 609.2 W, 124.32 times greater than that of 4.9 W at the natural resonant frequency. And the efficiency by using the proposed strategy is 87.04%, which is comparable to the efficiency of 89.91% by operating at the natural resonant frequency.