Voltage Multiplier Rectifier with Second Harmonic Resonance for Wireless Power Transfer System

A coupling coefficient k decreases as the size of the receiver coil decreases, when RF power is transmitted to small size devices such as implantable medical devices by magnetic resonant method. In this case, the rectifier efficiency using conventional voltage multiplier (CVM) is very low. The turn-on time of rectifying diode becomes unstable, when a low input voltage is applied to CVM, and power conversion efficiency (PCE) is reduced. In order to overcome this problem, we present novel voltage multiplier with second harmonic resonance (SRVM). Using the resonance of the second harmonic of operation frequency, the proposed SRVM overcomes the threshold voltage of diode with the induced voltage of the LC tank and achieves high PCE in the case of low coupling coefficient. When k is 0.01~0.05, the maximum PCE of SRVM is 77.5%, which is more than 51 % higher than CVM.