A Wireless Power Transfer System with Multiple Constant Current and Constant Voltage Outputs

This paper proposes a novel multi-load wireless power transfer (WPT) system with both constant current (CC) and constant voltage (CV) outputs. Repeater coils are used and every two repeater coils form a repeater unit. The bipolar coils are adopted in the proposed WPT system and the two coils in the same repeater unit are placed perpendicularly to realize magnetic decoupling. A ferrite plate is inserted between the two coils in the same repeater unit to not only enhance the magnetic coupling between two adjacent units but also suppress the undesirable magnetic coupling between any other coils. The series compensation topology is adopted for each coil. In the odd repeater unit the load is connected in series with the two repeater coils while in the even repeater unit the load is connected in parallel with the two coils. It can be derived that the CC and CV outputs can be obtained in the odd and even units respectively when neglecting the coil's parasitic resistance. The influence of the coil's parasitic resistance is also analyzed, which shows that with an enough coupling coefficient k and quality factor Q of the coil, the current and voltage drop due to the parasitic resistance is small and within an acceptable range. An experimental setup with 10 loads has been constructed and the results validate the effectiveness of the proposed WPT system.