Electrostatic vibrational energy converter with two variable capacitors

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The electrostatic two-capacitor vibration-to-electrical energy converter based on the Bennet doubler circuit with a power source in a variable capacitor branch is studied both theoretically and experimentally. The variations of the capacitances both in opposite phase and in-phase with different modulation depths are considered. Analytical expressions evaluating the energy converter main characteristics and enabling to significantly simplify the optimization process during the converter design are derived. It is shown that the theoretical results are in a good agreement with the obtained experimental data, making it possible to use them for the optimal converter parameters choice when developing electromechanical microgenerators or energy harvesters, active vibration and acceleration sensors, as well as threshold devices. The advantage of the investigated interfacing circuit of the two-capacitor vibration-to-electrical energy converter in comparison with the basic Bennet doubler circuit is the versatility and the ability of the converter to operate under the action of small mechanical vibrations (excitations) causing the capacitance modulation depth less than 2. It is also possible to vary the critical capacitance modulation depth within a rather wide range getting the autostabilization mode even for the capacitance modulation depth greater than 2. As a result, it becomes possible to expand both the range of used amplitudes of external mechanical vibrations and the necessary parameters of the used variable capacitors.