Lightweight

miniaturization

and high-frequency operation are among the main development trends in power supply technology. In 6.78 MHz wireless power transfer (WPT) systems

the complex impedance characteristics of converters at all levels make it difficult to clearly plan impedance trajectories when the system is applied to dual loads. It is challenging to achieve soft-switching characteristics of power amplifiers (PA) and functional output of load branches. To address this

this paper proposes a hierarchical structure design theory for impedance trajectories. By constructing an equivalent voltage source

the problem is decomposed into two stages for solution. While maintaining zero-voltage switching of the power amplifier

combined with a resonant/choke rectifier combination

different functional outputs of constant current/constant power are achieved. A physical prototype of a dual-load relay system was built to test the system's operational performance under different load conditions. When the total output power of the dual loads reaches 75.74 W

the system efficiency achieves 86.22%.