Abstract:
Dielectric elastomer (DE) generators are variable capacitors made from rubbery materials
and use the principle of electrostatic generation to harvest kinetic energy. Due to their
soft rubbery nature, they are uniquely suited to harvest energy from renewable kinetic
energy sources as they couple well to non standard mechanical impedances and complex
geometries. The generation cycle of electrostatic harvesters is non trivial and requires
charging and discharging of the DE in synchronization with its changing capacitance.
This thesis presents modelling and optimization of two circuits which achieve this synchronized
charge transfer automatically, while also providing voltage boosting. First a
review of existing generator technologies is performed followed by the fundamentals of
electrostatic generation. Next, areas where improvement is needed are identified and the
the self priming circuit is introduced. Following this a comprehensive model is developed
and optimization of voltage and energy gain is discussed. The second circuit, the integrate
self priming circuit is then modelled in a similar fashion and found to have significantly
higher voltage boosting. This thesis finishes with a comparison of the two circuits and the
theoretical maximum energy which an electrostatic harvester could achieve. It was found
that with practical consideration of cost and efficiency that the two circuits presented
are well suited for low to medium power harvesting scenarios.