Wireless Power Transfer System based on Unity-Gain Frequency Tracking

Wireless power transfer has been widely used in consumer electronic devices, mainly for battery charging. However, frequent charging and discharging of batteries cause power losses and shorten the battery lifetime. Also, certain applications prefer not to have any batteries at all. To remove the battery and optimize the load transient response without battery, a wireless power transfer based on unity-gain frequency tracking is proposed. At unity-gain frequency, the deviation of rectified voltage due to load transients on receiver side is minimized. During distance variation, the proposed method keeps tracking the unity-gain frequency online.