Circuital Modeling of a Droplet Electrical Generator

A droplet electrical generator (DG) is an energy harvester able to scavenge energy from water droplets sliding on its surface. A compact electrical model of a droplet generator is here presented together with a black-box identification procedure. Even if previous research works have shown the great potential of the droplet generator in terms of extracted power and have investigated the optimization of the device, a simple equivalent electrical circuit is not available, which is fundamental for predicting its behavior and for designing its electronic interface, devoted to maximizing the power extraction under varying source and load conditions. A detailed identification procedure for the model parameters is also presented, in order to overcome the issues due to the high voltage, low current, high bandwidth, and unknown time-waveform of the time-varying capacitances. It is also shown how the proposed model allows the designer to predict analytically and numerically the energy that can be extracted by the generator. Finally, experimental tests are presented to show that the proposed model and the outlined procedure are able to effectively predict with good accuracy the system behavior under different operating conditions.