A Comparison of Resonant Converter Topologies with Three and Four Energy Storage Elements for Automatic Inductive Charging Application

The full-bridge series-resonant, parallel-resonant, series-parallel type SP-LLCC and parallel resonant type PRC-LLCC converters are compared for use in automatic inductive charging applications. Three order and four order models must be considered if, as in the case of this paper, the effect of magnetizing inductance and leakage inductance of the inductive coupler is considered. Analysis and breadboard results show that the series-parallel resonant converter type LLCC with capacitive output filter while maintaining excellent efficiency. A useful analysis technique based on steady-state analysis and first harmonic approach is also introduced. The topology selection criteria are based on the major application goal: minimum size, high switching frequency which is necessary to reduce the values of the reactive components, and high efficiency is needed to avoid thermal constraints.