Wireless power transfer integrated board for low power IoT applications

摘要

IoT edge devices are of interest to sustainability research because of their support for low energy applications. This work focuses on a wireless power transfer (WPT) system at GHz frequency based on near field coupling (NFC) with a class E rectifier and DC-DC converter with power inductor, designed for loads in the mW range. The design is completed on an integrated board, allowing for integration of the WPT coils and power inductor on the circuit board with designed electrical characteristics. The WPT coils and class E rectifier are designed for maximum efficiency, minimizing the losses associated with high frequency, low power operation. A commercial off the shelf (COTS) buck converter is integrated into the architecture to fix the output voltage. The power inductor is fabricated with a Nickel Zinc ferrite epoxy composite screen printed on the top and bottom layer of the integrated board. The complete circuit design is fabricated and measured, with the total measured system efficiency peaking at 22.7% power efficiency at a WPT transmission distance of 2 mm.