Soft Switching Realization of LCCL-LC Resonant Converter for Wireless Power Transfer Application

The LCCL-LC resonant converter is a promising topology for wireless power transfer (WPT) systems and soft switching is essential to reduce the switching related loss and electromagnetic interference (EMI) noise for a high frequency system. In this paper, an analytical model considering the dead-time period to realize zero voltage switching (ZVS) in the LCCL-LC circuit is proposed. With the analytical model, the ZVS condition is derived for one-transmitter one-receiver case and then is extended to multiple-transmitter one-receiver case. A detailed comparative study of the existing current control methods in a multiple transmitter system is conducted in terms of ZVS. Finally, a 6.78MHz wireless charging system is built and the proposed ZVS model is validated by the experimental results. The peak system efficiency is 85% at 5W output level.