A New Inductive Power Transfer Topology Using Direct AC-AC Converter With Active Source Current Waveshaping

Generally, in wireless inductive power transfer (IPT) system, the power is processed through multiple power transfer stages and this leads to lower efficiency and higher cost of the system. Recent research shows that the use of a direct ac-ac converter in an IPT system compensates these limitations significantly. However, one of the major challenges of the IPT circuit with direct ac-ac converter is to achieve multiple control goals through a single converter. These include load power requirement, maintaining high-quality source current and achieving soft switching of inverter switches, etc. In the existing literatures, the research is more focused on meeting load power requirement and soft switching of inverter switches. The major focus of this paper is to propose, analyze, and control a new IPT power converter topology using current-fed direct ac-ac converter. Compare with existing buck derived, i.e., voltage source ac-ac converter topologies, the proposed topology is boost derived; therefore, active source current waveshaping is easily obtained. The complete control is carried out through two loops, where the outer output current loop ensures load requirements and inner loop maintains the high-quality grid current. The detail of steady-state and dynamic analysis and design procedure of the converter is presented. Experimental results obtained from a 1.2-kW lab-build prototype are included to verify the analysis and proposed control.