A systematic comparison of hard- and soft-switching topologies for inductive power transfer systems

This paper provides a comparison of four series-series compensated inductive power transfer systems for contact-less vehicle charging. A systematic comparison between hard-and soft-switching topologies, as well as different operating frequencies, is performed and the impacts on system efficiency and complexity are assessed in detail. In a holistic design process each system is individually optimized for a charging power of 3kW and a variable air gap from 100mm to 170mm at a coil diameter of 500mm. It is shown that the hard-switching topologies are highly attractive in the considered power range even with state of the art semiconductors. By introducing a dual-side controlled topology a superior system efficiency is demonstrated at an operating frequency of 35 kHz.