Optimization of the energy harvesting control for dielectric elastomer generators

Energy harvesting using dielectric elastomers is an upcoming possibility to convert ambient energy into electric energy. Published results for energy harvesting cycles deal with charging and discharging of the polymer during a constant stretch state. However, real applications feature a continuously changing stretch and thus the time frames of the charging-and discharging-intervals have a considerable influence on the amount of harvested energy. This paper presents the calculation of the optimal charging-and discharging-intervals to maximize the energy gain. For this purpose the authors investigate the physical model of a lossy generator to derive the converted energy as a function of the timing of the charging-and discharging-interval. The subsequent optimization results in an energy-optimal harvesting cycle that combines the fundamental harvesting cycles with constant electric field and constant charge. Finally, we present the achievable energy gain of this optimized harvesting cycle as well as control laws to realize the optimized harvesting cycle.