A High-Efficiency Wireless Power Transfer System Using Quasi-Z-Source Inverter and Current-Double Synchronous Rectifier for Low-Voltage and High-Current Applications

In low-voltage and high-current wireless power transfer systems (LVHC WPTSs), the loss of power loop is usually large due to the high current. More critically, the equivalent load resistance (ELR) is usually much lower than the optimal load resistance, which leads to serious heating and low system efficiency. This article proposes a new technology, which employs the current-double synchronous rectifier (CDSR) to replace the traditional diode rectifier and dc/dc converter on the secondary side, and thus, the ELR can be adjusted in a large range by regulating the duty cycle of CDSR and the system can always work at the maximum efficiency point. In addition, the traditional dc/dc converter and inverter are replaced by the quasi-Z source inverter (q-ZSI) on the primary side, which can boost the dc-link voltage of inverter and reduce the current of power loop, so as to reduce the heating and improve the system efficiency further. Furthermore, the cooperative working mechanism of q-ZSI and CDSR for high-efficiency and constant power (CP) charging is analyzed thoroughly. Finally, the viability of the proposed topology is verified in a 1-kW prototype with 48-V input and 24–33.6-V output voltage, and the maximum efficiency of the prototype achieves 87.4%.