SIMPLE AND AFFORDABLE POWERING CIRCUIT FOR IoT SENSOR NODES WITH ENERGY HARVESTING

Abstract

The paper presents a circuit structure that can be used for powering an IoT (Internet of Things) sensor node and that can use just the energy from its surroundings. The main advantage of the presented solution is its very low cost that allows mass applicability e.g. in the IoT smart grids and ubiquitous sensors. It is intended for energy sources that can provide enough voltage but that can provide only low currents such as piezoelectric transducers or small photovoltaic panels (PV) under indoor light conditions. The circuit is able to accumulate energy into the capacitor until a certain level and then to pass it to the load. The presented circuit exhibits similar functionality to a commercially available energy harvester (EH) EH300. The paper compares electrical properties of the presented circuit and the EH300 device, their form factors and costs. The EH circuit’s performance is tested together with buck-boost DC/DC converter LTC3531 which can provide constant voltage for the following electronics. The paper provides guidelines for selecting an optimal value of the storage capacitor. The solution presented’s functionality is demonstrated on a sensor node that periodically transmits measured data to the base station using just the power from the PV panel or the piezoelectric generator. Presented harvester and powering circuit are compact part of the sensor node’s electronics but it can be also realized as an external powering module to be added to existing solutions.