Synchronization Method for Wireless Power Transfer System by Detecting Voltage Transient on a Sensor Inductor

Active rectifier can achieve higher efficiency than an uncontrolled rectifier for the wireless power transfer (WPT) system. However, synchronization is a challenge for both sides' safe and reliable operation of converters. This article proposes a novel synchronization method for the WPT system. Its most significant advantage is that it is not affected by system detuning and can be implemented at any operating frequency. An equivalent sensor inductor (magnetic ring with multiple turns of wire) is connected in series to the resonant tank at the receiving end. The sudden change of the inverter output voltage will cause the voltage transient in the sensor inductor. By detecting and tracking the voltage transient, the frequency and phase synchronization of both sides can be achieved. Experimental results applied to triple-phase shift control also demonstrate that this method can be widely used in multiphase shift control on both sides.