Analytical Evaluation of S-S and LCL-S Compensated Wireless EV Chargers with Partial Power Conversion

A wireless charging using wireless power transfer (WPT) technique is the future of electric vehicles (EVs). With the implementation of wireless charging, efforts on modifying the plug-in EV charging infrastructure compatibility could be reduced. WPT system basically works on the principle of electromagnetic induction. WPT has basic two types, inductive power transfer (IPT) and magnetic resonance coupling (MRC) power transfer. For a conventional IPT, two-stage structure is one of the most common topologies, of which the efficiency will be dramatically decreased by a cascaded dc-dc converter. To overcome the issue, in this paper, various partial power processing (PPP) converter (PPPC) architectures for wireless chargers are shown and a detailed analytical evaluation of S-S and LCL-S compensated topologies is given. With PPP based architectures, the system efficiency is improved, and the converter size is reduced. The WPT receiver is divided into the main receiver and the auxiliary receiver, i.e. dual receiver. Most of the power is transferred to the load through the main receiver, whereas the auxiliary receiver is used to regulate the output voltage. As a result, the switching loss and device stress of the dc-dc cascaded at receiver can be significantly reduced.