Dynamics of Electrostatic Systems for Energy Conversion Applications

Abstract

The work presented here describes the electrostatic force, it’s nature, and it’s use in electromechanical systems. Energy transfer from both electrical-to-mechanical and mechanical-to-electrical are described. The electrostatic force is investigated in detail.Patterning of electrostatic rotary capacitive plates provides a novel strategy for up-converting low frequency mechanical excitation sources. The rotating plates allow for output waveform signal conditioning in both control of frequency and waveform shaping. An experimental set-up consisting of a 5.08 cm (2”) diameter rotary electrostatic capacitor harvester was designed and tested at mechanical rotation frequencies ranging from 1–35 Hz. Quarter plates were used to double the rate of change in area. Plates were spaced 3 mm apart with an applied voltage of 6.55 kV maintained by a 8.3 nF capacitor bank. Resistive loads between 10kΩ−10M Ω were used to verify current flow from the rotary capacitor. Simulation was carried out using a current source GTABLE model in PSPICE. Electrostatic theory demonstrates similar current magnitudes and the same upward trend with frequency. Further experimental analysis of a translating spring-mass system with a constant electrostatic force in the presence of viscous damping is presented and compared with simulation. A model for the linear translating electrostatic system not under the influence of viscous damping is first considered. An analytical equation is derived which provides a theoretical model for the behavior of the system and simulation in carried out and compared with the solution and theoretical model. Next, an approximate analytical solution to the electrostatic oscillator system in the presence of viscous damping is completed and a recursive relationship for the piecewise solution is presented. Conclusions and future work suggest several avenues for further investigation where the electrostatic force in electromechanical systems could be advanced including application areas.