Constant current (CC) and constant voltage (CV) combined charging is considered as the most popular and efficient method for charging batteries. There are a lot of works done to achieve CC/CV characteristics by utilizing reconfigurable circuits for easy control but without the consideration of efficiency optimization in the CV mode. In this paper, the optimization of mutual-inductance proportion between transmitter/receiver mutual inductance and transmitter/intermediate mutual inductance of the three-coil circuit is investigated to maximize the time-weighted average efficiency (TWAE). With two switches, a section of receiver coil of the series-series (SS) circuit, which corresponds to the optimized mutualinductance proportion, can be converted into an intermediate coil of the three-coil circuit. Therefore, the system can be transferred from the CC mode to CV mode, and with the optimized mutual-inductance proportion, the efficiency in the CV mode can be improved. An experimental prototype is built to validate the feasibility of the proposed approach. In the CC (CV) mode, the impedance range is 30-108 (108-500), and the maximum fluctuation for current (voltage) is 3.37% (4.55%). Besides, the TWAE is 94.5% (maximum 95.3% and minimum 94.49%) for the three-coil circuit, while that of SS circuit with control is 91.54% (maximum 95.20% and minimum 85.31%). INDEX TERMS Inductive power transfer (IPT), wireless power transfer (WPT), reconfigurable topology, constant current/constant voltage (CC/CV), zero-voltage switching (ZVS).

No abstract

No abstract

Decoupling of same‐sided coils is a critical issue for multi‐input and/or multi‐output inductive power transfer (IPT) systems. The mutual inductance between the same‐sided coils may lead to the system detuning and the decrease of power transfer capacity and efficiency. In this study, a tetra polar ring coils (TPR‐coils) and its decoupling method are proposed for IPT systems applied to rotary mechanism. Firstly, an analytical expression, which illustrates the relationship between the mutual inductance and geometric parameters of coaxial cylindrical helical coils, is given. Then the equivalent circuit model of TPR‐coils is established, and the mutual inductance constraints for the decoupling of TPR‐coils are proposed. Combined with the expression of mutual inductance, a geometric parameter solution of decoupled TPR‐coils is derived. The correctness of theoretical analysis is verified by finite element method simulations and experiments. The experimental results show that the mutual inductance between the same‐sided coils can be reduced to 0.6 μH, and the effectiveness of TPR‐coils is also verified on an IPT prototype with 231 W power and over 86% efficiency.

No abstract