Study on frequency-tracking wireless power transfer system by resonant coupling

Detuning is the application barrier of resonant coupling wireless power transfer. This paper analyzes the effects about inductance variations of launch coil and receiving coil to wireless transmission efficiency from its transmission mechanism and model, and also analyzes detuning mechanism. And thus, it reveals that transmission efficiency has a great affection with inductance of launch coil changing. In order to make sure that wireless power transfer by resonant coupling operates without detuning, a new method of frequency tracking control is came up with, which is, making frequency of transmitting power source tracking with the nature frequency of launch resonant circuit automatically. Hence, it avoids detuning and improves transmission efficiency greatly. Finally, a prototype of 1 MHz wireless power transfer system by resonant coupling was made. Experimental results prove this method very well.