Experimental Study of Efficiency with Inductance Load and Relay Coil for Magnetic Field Coupling WPT

In magnetic field coupling wireless power transmission, the effects of inserting a parasitic coil between the transmitter and receiver coils and inductance loading on the wireless power transmission efficiency were investigated through measurements using a vector network analyzer. We achieved the significant improvement in wireless power transmission efficiency from 8 % to 44 % at the design frequency of 2 MHz by inserting the parasitic coil for relay between transmission coil and received coil on all of which were impedance loaded, while the improvement in efficiency was only a few per cent when either inductances were loaded or only relay coils were inserted. The measured and analyzed results of both efficiency and maximum efficiency were very similar variation for frequency, although the levels of efficiency of experimental results are less than analyzed one.