Load-Independent Duality of Current and Voltage Outputs of a Series- or Parallel-Compensated Inductive Power Transfer Converter With Optimized Efficiency

Inductive power transfer (IPT) systems are resonant converters whose output characteristics are mostly load dependent. Conditions for load-independent voltage-transfer ratios of IPT systems have been studied. However, load-independent current output can be more desirable for applications such as battery charging and LED driving. Theoretical operating frequencies for maximal efficiency of operation and load-independent voltage output of the IPT system have been explored in our previous paper. Using the duality concept, the system should exhibit similar characteristics as an IPT current output converter. Thus, in this paper, operating frequencies for maximal efficiency of operation and load-independent current output of the IPT system are explored, the aim being to identify some practical power-conversion efficient and load-independent operating frequencies. Analysis for the series- and parallel-compensation techniques is performed in order to facilitate the design of output current converter with an efficient power conversion and a load-independent frequency of operation. The analysis is supported with experimental results.