Input impedance matched AC-DC converter in wireless power transfer for EV charger

This paper provides experimental verifications of the AC-DC converter for an electrical vehicle (EV) battery charger which an input impedance is matched to a characteristic impedance of a transmission line. In a high-frequency wireless power transfer system such as a magnetic resonant coupling (MRC), the input impedance of the AC-DC converter in the receiving side of the wireless power transfer should be matched to the characteristic impedance of the transmission line in order to suppress the reflected power. This paper presents the fundamental characteristics of the AC-DC converter. The experimental result shows that the AC-DC converter enables a conversion from 13.56 MHz AC to DC with input impedance of 29.6+j0.51 Ω. Thus, the reflection coefficient is suppressed by 17.8 points compared with that of the conventional capacitor input-type diode bridge rectifier with 25 Ω of a load resistance. The suppressed reflection coefficient can reduce the reflection loss of the wireless power transfer system.