Portable battery charging circuits for enhanced magnetic resonance Wireless Power Transfer (WPT) system

In recent years there has been significant development in the field of consumer electronics and biomedical applications based on wireless power transfer technology. In this paper, we propose efficiency improvement method for magnetic resonance Wireless Power Transfer (WPT) at a particular frequency within ISM band, applying controlled Impedance Matching technique. The impedance matching network guides the system to maintain the resonance condition when distance between Transmitter (Tx) and Receiver (Rx) is varied, which results in high power transfer efficiency. Measured results with proposed scheme showed an average of 7.21% improvement in power efficiency for distance between 10cm to 100cm. In addition an on-chip high efficient power recovery scheme is designed and fabricated in Dongbu HiTek´s (DBHs) 0.35μm BCD technology based on LOCOS 0.35μm CMOS process for portable battery recharging applications. A maximum overall efficiency be 70.2% was determined for the entire system. This work shows the potential of automatic adjustments of parameters, such as impedance, in order to maintain resonance frequency to attain the maximum power efficiency and also to make the device portable.