Operation features of electrostatic vibrational energy harvester based on contact potential difference

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The paper presents a theoretical study of the electrostatic vibrational energy harvester (e-VEH) operation features based on the work function difference between the variable capacitor electrodes. The analysis was carried out for two types of the conditioning circuits: half-wave rectifier and Bennet doubler circuits both with ideal switches and diodes. Both circuits are able to accumulate electrical energy even for low contact potential differences Vbi. Bennet doubler demonstrates higher efficiency than the half-wave rectifier. However, when the variable capacitance modulation depth η ⩾ 2 it is necessary to introduce special means to limit the voltages growth process and avoid an electrical breakdown for the Bennet doubler circuit. For both circuits with diodes the capacitor voltages become lower than those for the circuits with switches and depend now not purely on the built-in voltage Vbi and η, but also on the used diode parameters. When the values of Vbi increase the capacitor voltages for circuits with diodes tend to the corresponding voltages for the circuits with switches. There is also a strong dependence of the capacitor saturation voltage VC1,max on inverse current of the diodes IS. The optimal inverse current of the diodes when the highest saturation voltages are reached is found to be in the range from 50 pA to 100 pA.