Harmonic Current Control for Wide ZVS Operation of Single-Stage WPT Resonant Converters

Wireless power transfer (WPT) is becoming increasingly popular in consumer electronics. To realize compact WPT systems, low to high-frequency single-stage converters have been widely studied, but without maintaining zero-voltage switching (ZVS) over a wide load range and input voltage to improve efficiency and electromagnetic interference. This article, therefore, proposes an asymmetric modulation method that extends the ZVS range by altering the amplitudes of the second and third harmonic currents of the converter. Experimental results of a 192-W prototype are presented to demonstrate how the ZVS can be achieved over 48–192 W power output and 80–110 V input voltage, with maximum efficiency reaching 90.9%.