A High-Efficiency Integrated LCC/S WPT System With Constant Current Output

In some practical applications such as battery charging and LED driving, it is desirable for the wireless power transfer (WPT) systems to have load-independent constant current output (CCO) characteristic. However, the existing WPT systems with CCO function suffer from low efficiency, limited output current by the loosely coupled transformer (LCT) parameters, low space utilization, and high cost. In order to solve the above issues, this article proposes a new integrated LCC/S WPT system with CCO function, in which the transmitter-side compensation inductor and the transmitter-side coil are coaxially and symmetrically stacked on the same plane to save space occupied when they are placed separately in the traditional structure. A detailed mathematical derivation of the proposed integrated LCC/S WPT system with both load-independent CCO characteristic and zero phase angle (ZPA) operation is carried out, and the explicit corresponding parameter design method is provided. It is worth emphasizing that the output current of the proposed integrated LCC/S WPT system is not limited by the LCT parameters due to sufficient design freedom. Then, a comprehensive theoretical analysis on the realization of zero voltage switching (ZVS) operation for higher overall efficiency and the impact on the CCO characteristic by slightly adjusting the parameters of the compensation capacitors is performed. Furthermore, a detailed and thorough efficiency comparison between the proposed integrated LCC/S WPT system and the SS WPT system is performed under alignment, long-distance, and misalignment conditions to reflect the efficiency advantage of the proposed system. Finally, a demonstrative experimental prototype with 60-V dc input voltage and 4.9-A CCO is fabricated to validate the correctness and rationality of the proposed integrated LCC/S WPT system and the corresponding theoretical analysis.