A Comparative Study of Switched-Capacitor and Inductor-Based Boost Converters for Indoor Light Energy Harvesting

With the development of sustainable and energy-efficient smart buildings and cities, scavenging indoor light energy to power the Internet of Things (IoT) has become an increasingly attractive solution. This solution helps to extend the lifespan of devices by reducing the frequency of battery replacement whilst resulting in less battery waste. However, the energy that can be harvested from an indoor light environment is limited compared to natural, outdoor sunlight, emphasizing the importance of efficiency of the entire energy harvesting system rather than that of individual harvesters. Power management circuitry plays a crucial role here but there has not been a system-level study for different power management schemes when connected to both harvesters and batteries whilst working under real lighting conditions. In this talk, performances of both a Switched-Capacitor (SC) and an Inductor-based (IN) boost converter will be evaluated with reference to their charging efficiencies when connected to photovoltaic cells and Li-ion batteries under indoor office light. Results suggest that, although the IN converter tends to be cumbersome, it provides unbeatably high and stable battery charging efficiency across a broad range of light intensities compared to the SC converter even though the latter is specifically designed for low-power applications competing with the IN counterpart.