A wireless power transfer system based on impedance matching network

In this paper, we design a wireless power transfer (WPT) system based on the impedance matching network to achieve highly efficient wireless power transmission from a power source of 220 V/50 Hz to a 50 kHz transmission power to a 25 kHz alternating current (AC) output power. The proposed WPT system is composed of primary rectifier-filter module, DC-DC buck module, primary inverter module, primary impedance matching module, WPT module, secondary impedance matching module, secondary rectifier-filter module, and secondary inverter module. With the used of the secondary impedance matching module, the WPT module with the optimal transfer efficiency can be achieved. By introducing the primary matching module, the efficiencies of the primary inverter module and the DC-DC buck module are improved and meanwhile the equivalent input impedance of the WPT module is increased to suppress the excessive primary-side current caused by the removal of the receiving coil. The proposed prototype system has been fabricated, and the measurement results demonstrate that the system efficiency of 57% can be obtained with a distance of 30 mm at the 42 W input power.