Title :
Analysis and Tracking of Optimal Load in Wireless Power Transfer Systems
Author :
Minfan Fu ; He Yin ; Xinen Zhu ; Chengbin Ma
Author_Institution :
Univ. of Michigan-Shanghai Jiao Tong Univ. Joint Inst., Shanghai Jiao Tong Univ., Shanghai, China
Abstract :
All the wireless power transfer (WPT) systems share a similar configuration including a power source, a coupling system, a rectifying circuit, a power regulating, and charging management circuit and a load. For such a system, both a circuit- and a system-level analyses are important to derive requirements for a high overall system efficiency. Besides, unavoidable uncertainties in a real WPT system require a feedback mechanism to improve the robustness of the performance. Based on the above basic considerations, this paper first provides a detailed analysis on the efficiency of a WPT system at both circuit and system levels. Under a specific mutual inductance between the emitting and receiving coils, an optimal load resistance is shown to exist for a maximum overall system efficiency. Then, a perturbation-and-observation-based tracking system is developed through additional hardware such as a cascaded boost-buck dc-dc converter, an efficiency sensing system, and a controller. Finally, a 13.56-MHz WPT system is demonstrated experimentally to validate the efficiency analysis and the tracking of the optimal load resistances. At a power level of 40 W, the overall efficiency from the power source to the final load is maintained about 70% under various load resistances and relative positions of coils.
Keywords :
DC-DC power convertors; inductive power transmission; radiofrequency power transmission; WPT systems; cascaded boost-buck DC-DC converter; charging management circuit; circuit-level analysis; coupling system; efficiency sensing system; emitting coils; feedback mechanism; frequency 13.56 MHz; mutual inductance; optimal load analysis; optimal load resistance; optimal load tracking; perturbation-and-observation-based tracking system; power 40 W; power regulation; power source; receiving coils; rectifying circuit; system-level analysis; wireless power transfer systems; Coils; Couplings; DC-DC power converters; Impedance; Integrated circuit modeling; Resistance; Resonant frequency; Efficiency analysis; inductive resonance coupling; tracking of optimum load resistance; wireless power transfer;
Journal_Title :
Power Electronics, IEEE Transactions on
DOI :
10.1109/TPEL.2014.2347071