Modular Platform for Efficient Wireless Power Transfer to Low-Power Devices

To tackle the economic and ecological challenges introduced by batteries, and avoid their massive deployment in low-power IoT devices, a modular platform is developed to transfer power wirelessly to these devices. The modules in the proposed system are based on a phase-locked loop (PLL) frequency synthesizer and are judiciously controlled by an on-board microcontroller in a scalable way. These features enable the combined system to implement beam-forming or function as a frequency-diverse array (FDA) to increase the wireless power transfer (WPT) efficiency by generating a high peak-to-average power (PAPR) ratio. Each of the fabricated prototypes can be digitally configured to output a power from 17.5 dBm up to a maximum of 24.5 dBm at 2.45 GHz. Measurement results show that the efficiency of an existing rectifier can be improved by 23% at -20 dBm when increasing the PAPR by 3 dB. Finally, the system is put to the test in a practical WPT scenario, herein achieving a better WPT efficiency at low power levels when configured as an FDA.