Design and test of a Bennet's doubler device with mechanical switches for vibrational energy harvesting

Abstract

In this work, we demonstrate that the use of self-synchronized mechanical switches in replacement of diodes into electrostatic vibration energy harvesters (e-VEH) can lead to better power generation. Indeed, mechanical switches have the advantage of no leakage current and no threshold voltage. As a proof of concept, we use the Bennet's doubler electrostatic generator. The proposed e-VEH is composed of two variable capacitors triggered by a central electrode taken as an inertial mass. Ambient vibrations induce inertial forces on the central electrode, as a result a voltage doubling is obtained at each operating cycle. The mechanical switches are directly fixed to the moving electrode. In addition, no dedicated pre-charge is required: the system starts with ambient electrical charges. The device is fabricated and tested under harmonic motion. A comparison between the proposed design and those using diodes under the same operating conditions shows an experimental direct increase of the harvested electrical power of around 28%.