Two-Coil Resonant Wireless Power Transfer System for Smart Recycling Containers

The increasing use of internet of things (IoT) devices in Smart Cities demands a reliable, low-maintenance power supply. Energy harvesting from solar sources is common, but not always feasible for devices with higher power needs or in areas with limited sunlight. Smart Recycling Containers with compaction systems exemplify this challenge, as they are often placed in locations with minimal sunlight and experience irregular movements, making wired power supply difficult. In this context, wireless power transfer (WPT) presents a promising alternative. This paper introduces a cost-effective two-coil resonant WPT system designed for smart containers, developed and validated through the ECO-IoT R&D project. The system achieves wireless power transmission up to 35 W over distances ranging from 5 cm to 1 m with a peak efficiency of 78 % at 15 cm. By operating at relatively low resonant frequencies and ensuring sufficient separation between coil windings, the system minimizes losses due to the proximity effect. It also allows the use of common stranded wire instead of Litz wire without significantly sacrificing efficiency. The proposed system provides a simplified energy supply solution for Smart Containers and other devices benefiting from cost-effective wireless charging. Experimental results validate the system’s feasibility and effectiveness, making it suitable for real-world deployment in urban settings.