Novel method for electrically tuning the resonant frequency of Piezoelectric Vibration Energy Harvester (PVEH) by using low power actuation
Date
2024-01-10
Authors
Raghavan, Sreekumari
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
Advancements in electronics and MEMS (Micro Electro Mechanical Systems) technology have enabled the deployment of a large number of sensors and signal transmitters on structures at critical locations to extract vital data and avoid catastrophic failures. This approach leads to condition- based maintenance of structures. In this scenario, the critical requirement is an autonomous power source that can power the system. In most cases, wired connections to a central power unit are not feasible, resulting in the use of batteries to power the sensors and transmitters. In recent years a great deal of research has been focused on harvesting from solar, thermal, kinetic, and RF (Radio Frequency) energy available in the environment. Of all these ambient conditions, kinetic energy in the form of vibrations is more prevalent in many structures and machinery. This has resulted in an increased focus on effectively converting vibration energy to electrical energy. Among many methods adopted, the application of piezoelectric materials has led to promising results. A piezoelectric energy harvester in a cantilever design can generate high power output, only at its resonant frequency and much research has been focused on methods of tuning the harvester to match the ambient frequency of vibrations.
This dissertation details an active tuning methodology and design of a device, which has resulted in achieving a net power gain. The concept is to utilize a low power actuation mechanism integrated with the harvester to enable active tuning of the resonant frequency of the device. The approach was to make use of Ionic Polymer Metal Composites (IPMC) for the required actuation. IPMC is a smart material, whose actuation can be altered by varying the input voltage to the device.
The IPMC used here is perfluorinated Nafion films with noble metal coated on both sides as electrodes. When subjected to an applied voltage, the free cations in the membrane, tagged to the water molecules, move to the negative electrode. This phenomenon creates bending of the film. This is the actuation process associated with IPMC.
The actuator unit of two strips of IPMC, attached at the tips was powered by a very low voltage ranging from 1 to 4 V. The various levels of actuation generate corresponding block forces and functions as equivalent to tunable stiffness stoppers. This dissertation provides details of experiments carried out, theoretical analyses, and the applications of this novel device.
Description
Keywords
Piezoelectric Vibration Energy Harvesting, Resonant frequency tuning, Ionic Polymer Metal Composite, Actuation, Macro Fiber Composite, Micro Electro Mechanical Systems