Wireless power transfer via resonant magnetic coupling for low power devices

Abstract

Wireless power transfer system can transmit the energy without any physical contact. Wireless power system can be divided into transmitter and receiver. The transmitter receive energy source from the power supply and transfer to the receiver via coupling method. There are three types of coupling methods; that is magnetic coupling, resonant magnetic coupling and capacitive coupling. The resonant magnetic coupling are most suitable for the wireless power transfer in mid-range. This is due to its high oscillating frequency that causes the induced voltage transfer from the transmitter to receiver. This project is to simulate and construct the wireless power transfer system. A DC power supply conduct 12V to the transmitter circuit. The transmitter made up of oscillator circuit and resonator circuit. The DC input voltage can be invert to AC by using the switching process of the MOSFET and the voltage passes through the resonator circuit. The resonator circuit was able to produce the high oscillating frequency to transfer the current to the receiver. The alternating voltage receiver will be rectified by bridge rectifier, filtered by capacitor to remove the ripple, and regulated, then an essential DC voltage transferred to a DC fan. The output voltage is varied by the distance between transmitting coil and receiving coil. Hence, the effectiveness of the proposed wireless power transfer system is evaluated by experimental results of the prototype. Therefore, the relationship between efficiency and distance is studied. The obtained experimental results are found agreed with theoretical and wireless power transfer is achieved.