Transmission Distance Improvement of a Two-Coil Magnetic Resonance Wireless Power Transmission System Using Transformers

In this paper, a two-coil magnetic resonance wireless transmission system is studied to improve the transmission distance using transformers. A conventional two-coil and four-coil wireless power transmission (WPT) system as well as a two-coil WPT system with transformers are analyzed comparatively via circuit simulations and experiments. Circuit analysis was used to predict the transmission distance with the highest efficiency. To verify the improvement in the transmission distance of the proposed system, transformers with inductance values of 80, 100, and 140 μH were fabricated and analyzed through experiments and simulations. A maximum S21 parameter of 0.76 was noted when the inductance was 80 μH and the transmitting distance was 4 cm. The experimental results almost matched the simulation results. From the experiments, it was shown that the transmitting distance of a WPT system can be adjusted by using transformers. Additionally, it was found that the transmitting distance is inversely proportional to the transformer inductance, and the efficiency of the WPT system decreases with the transmitting distance.