Design and characterization of a power transfer inductive link for wireless sensor network nodes

This paper describes a design of a power transfer inductive link for charging batteries of wireless sensor network nodes. The application physical constraints imposes a maximum size for the coils and demands a design methodology to maximize output power delivered to the load and energy transmission efficiency. This paper presents a complete methodology for designing the coils of wireless power transfer systems applied to rechargeable batteries of wireless sensor network nodes. The design of an inductive link is presented as a case study, in which two planar coils are built in order to validate the proposed method. Moreover, a complete wireless power transfer system is developed for the proposal, including coils, primary power source, capacitor network compensation, and secondary power management, with rectification, filtering, regulation, and battery charge control. The experimental results for working distances between the coils from 1 mm to 10 mm are reported as well as the frequency response of the entire system.