No abstract

This study proposed a hybrid inductive and capacitive wireless power transfer system to achieve high-power transfer by combining inductive power transfer (IPT) and capacitive power transfer (CPT). A traditional IPT system imposes a high voltage on the transmitter because of resonance. Meanwhile, high voltages are required to establish an electric field to deliver power to the CPT system. Therefore, they can be combined to a hybrid system to achieve high-power transfer by utilising two power transfer paths. A general model of the hybrid IPT and CPT coupler is analysed in detail. With a series-series compensation topology, 1.1 kW hybrid system with equal power transferred by two paths is simulated and set up to evaluate the performance of the proposed method. An experimental prototype is built under various conditions, and the result shows that the hybrid system achieved 1.1 kW output power through both of magnetic path and of electric path successfully with 91.9% DC-DC efficiency.

No abstract

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).

Wireless power transfer (WPT) for charging electric bicycles (EBs) can save people from tiresome plugging actions and avoid electrical shock hazards, especially in adverse weather. This study proposed a two-/three-coil hybrid topology to achieve constant current (CC) and constant voltage (CV) for charging EBs, simplifying control schemes. The system realises CC output with two-coil topology and operates in CV mode with three-coil topology by turning on a switch. Besides, an inductor array is used to compensate reactive power in CV mode when massive EBs are charged by one high-frequency inverter (HFI). The secondary side of the proposed topology is compact, and the number of components and HFI can be reduced. A coil design process based on doubleD type for the three-coil system is given, with the constraint of mutual inductances among three coils and limited size. To demonstrate the validity of the proposed methods, an experimental setup is built, and the performance of the two-/three-coil hybrid system indicates that the fluctuations of charging current and voltage are <0.64 and 2.12% in the whole charging profile. Moreover, the performance of two WPT chargers connected with one HFI hints that massive EBs can be charged with only one HFI.