Reduction Method of Electromagnetic Interference in Tightly-Coupled Resonant Magnetic Field Automotive Charger with Input Impedance Design

In this paper, we propose electromagnetic interference (EMI) reduction method in tightly-coupled resonant magnetic field automotive charger. The main technique for reducing EMI is input impedance design based on theoretical analysis of tightly coupled wireless power transfer (WPT) circuit. In order to design input impedance of the tightly coupled WPT circuit, the characteristics of the magnitude of the input impedance curve with the frequency splitting phenomena should be analyzed. From these theoretical analyses, the circuit parameters for increasing the magnitude of the input impedance at harmonic frequencies are designed. To verify the method, we compare total harmonic distortion (THD) between the proposed WPT system and the typical tightly coupled WPT system with series-series resonant topology using the ANSYS Simplorer. The simulation results of the proposed WPT system show that THD of Transmitter(Tx) and Rx currents flowing through Transmitter and receiver coil are reduced by 53.85% and 39.52% respectively.