A Primary-Sided CLC Compensated Wireless Power Transfer System Based on the Class D Amplifier

In order to reduce the complexity of the high-frequency AC power supply of the wireless power transfer (WPT) system in small and medium power applications, the class D amplifier is adopted in this paper. The class D amplifier, which has fewer components than traditional full-bridge and half-bridge inverter, simplifies the structure of the WPT system and can realize the zero-voltage turn-on of MOSFETs. Meantime, a primary-sided CLC compensation network is proposed to achieve load-independent constant voltage output of the WPT system. The analysis and design procedure for the WPT system are provided and a prototype is built. Simulation results validate the load-independent voltage output characteristic of the circuit topology. Experiment is executed at a transfer distance of 10cm and the results show that when the load resistor changes by 233 % from 15Ω to 50Ω, the output voltage only fluctuates by 2.6V from 33.2V to 35.8V. The fluctuation rate is only 7.8%, which indicates that the output voltage of the WPT system is robust to the load variation. With a load resistor of 25Ω, the experimental prototype reaches a dc-dc efficiency of 87.57% at 48.16-W output power.