AN INDUCTIVE POWER TRANSFER SYSTEM WITH A HIGH-Q RESONANT TANK FOR PORTABLE DEVICE CHARGING

Abstract

Since the soaring market size for portable electronic and communication devices, inductive power transfer (IPT) as one of the wireless charging methods has received great interest by researchers and industries due to many advantages. The power transfer efficiency of an IPT system is highly dependent on the quality factor (Q) of the resonant tank. In the thesis, a novel structure of the resonant coil, which consists of alternately stacked C-shaped conductor layers and toroid-shaped dielectric layers instead of traditional litz wire, is designed and fabricated to achieve a significantly high Q. An IPT system for portable device charging is designed and constructed to deliver energy from a DC power supply at the primary side to a constant load at the secondary side through an air gap. A frequency tracking unit is implemented to maintain the resonant status by catering the change of the resonant frequency and a standby unit is implemented to reduce the power consumption when the secondary coil is absent. The experimental results show that by using the specially designed resonant coil with a Q of 1200, the proposed IPT system allows power to be effectively transferred at a maximum air-gap distance to coil diameter ratio of 1.46 for a highest overall efficiency of 87% at the resonant frequency of 106 kHz.