Low Voltage Wireless Power Transfer (WPT) Using Resonant Inductive Coupling Charging for Short-Range Operation

An inductive coupling technique was used to transfer an electrical energy wirelessly from transmitter to receiver circuits, which used same resonance frequency to obtain maximum power transfer. As the coil inductor of 7 mu H and the resonating capacitor of 1 mu F are specified for air-core coils to produce resonant frequency, the simulation of wireless power transfer (WPT) system was done using Multisim software. The experiment showed that electric power is transferred at a frequency of approximately 60 kHz with an efficiency of 94% with resonant coupling. Whereas, the maximum output voltage at both transmitter and receiver circuits were 16.5 V and 15.5 V, respectively. The maximum air gap distance was 8 cm to charge a lower power device. Furthermore, resonant coupling repeater enables to extend the distance with approximately 4 cm as well as acts as a guide path which proved the efficiency of the WPT can be further improved via resonance coupling and frequency repeater. Thus, this WPT system is suitable to charge low power electronics such as implantable biomedical devices, remote sensing and portable electronics.