MODELLING OF ENERGY STORAGE FOR INDOOR/OUTDOOR LIGHT ENERGY HARVESTING

With IoT, billions of physical sensors/actuators nodes will be connected to the internet. Due to their massive quantity, the only sustainable way to power them is through environmental energy harvesting (EH). The major subsystems of an indoor/outdoor lighting EH system are the PV cell to harvest light energy, and energy storage device to store the harvested energy.
In this project, the energy storage and wireless sensor node were worked on primarily. Energy storage devices that were used to power up the wireless sensor node include NiMH cells. The wireless sensor node consisted of a temperature and humidity sensor which then transmitted data via radio modules.
To obtain the battery characteristics in the energy harvesting system, some parameters had to be acquired. These included the series resistance, parallel resistance, and parallel capacitance. This was done by pulse charging a battery at 1C for 1 minute. Then, the parameters were obtained using several formulas.
The data obtained from the discharge experiment was also input into a simulation model. From there, comparisons between experimental and simulated data were made to verify whether the modelling of the battery is within the boundaries or not.