In order to achieve voltage regulation of wireless power transfer(WPT)system based on AC envelope modulation

according to the impulse theorem and the energy conservation principle

energy injection mode combined with free oscillation mode were used. The energy scale of primary part is adjusted to adapt for the changes of load

therefore

the output voltage regulation is realized. Simulation and experimental results illustrate that the output voltage of system keeps constantly in a dynamic load switch period. This work is supported by National High Technology Research and Development Program of China(863 program)(No. 2015AA016201)and National Natural Science Foundation of China(No. 51377183).