The Design and Effect of Power Electronics on Vibration-Based Energy Harvesting Methods

Recent advancements in low-power sensor nodes have led to data acquisition systems for applications such as heart monitoring, and building environmental controls. Often these systems
are in locations characterized by limited access to electrical power, yet are in the presence of ambient mechanical vibrations. Therefore, energy harvesting from mechanical vibrations is proposed as a solution for powering these wireless sensor nodes. This dissertation focuses on the power electronic interface between vibration energy harvesting devices and electrical energy storage elements for piezoelectric and variable-capacitance energy harvesting systems.
The DAEH method has been proposed as a way to widen the bandwidth of resonant piezoelectric energy harvesters; however, an autonomous system has not been demonstrated. A new energy harvesting system is proposed that includes a resonant inverter topology, in conjunction with new low-power analog control circuitry, in order to produce the first wideband autonomous DAEH system. Experimental results demonstrate an 86% improvement in energy harvesting bandwidth over the current state-of-the-art. These results include previously ignored loss mechanisms; making this system the first autonomous energy harvesting system of its kind.
Including power electronic efficiency as a parameter in the analysis of variable-capacitance energy harvesting, new fundamental properties of these devices are derived: a threshold efficiency necessary for energy harvesting, analytical solutions for optimal harvesting conditions, a comparison of energy harvesting methods at practical power electronic efficiencies, and a comparison of energy harvesting capabilities of various device architectures.