A Practical Z-parameter Two-Port Modeling Method to Evaluate Long-Distance and High-Efficiency Wireless Power-Relay Systems

In Wireless Power Transfer (WPT) system, applying power-relay coils is an effective method to achieve both long-distance and high-efficiency. However, the Wireless Power-Relay System (WPRS) has many variables, which will perplex the system design. An evaluation method based on black-box Z-parameter two-port model is introduced for the WPRS. This method can easily obtain the theoretical optimal efficiency and corresponding load from black-box measurement instead of acquiring all the parameters of the resonant coils. This feature can be used to compare potential performance of different WPRS. WPRS based on PCB coils are built to verify the black-box Z-parameter two-port modeling. Experiments are also carried on WPRS AC resonant tanks and WPRS DC/DC converters.