Modelling and Comparing Converter Architectures and Energy Harvesting ICs for Battery-Free Systems

Battery-free energy-harvesting devices are a new class of embedded systems that operate from ambient energy stored in environmentally-friendly capacitors and promise long-lasting, maintenance-free operation. Due to tight energy constraints, these devices often employ voltage converters and dedicated integrated circuits (ICs) to maximize the power transfer between energy harvester, storage capacitor, and load. As we show in this paper, the selection and configuration of such converter circuits are important, but non-trivial, as their performance is highly dependent on the energy harvesting conditions. We thus provide models of five off-the-shelf energy harvesting ICs and integrate them into an open-source simulator for battery-free systems: this allows practitioners and researchers to conveniently explore the design trade-offs and anticipate the achievable performance. Furthermore, we use these models to perform a systematic comparison of different converter architectures and derive concrete recommendations.