High-Performance Piezoelectric Vibration Energy Harvesting for Railway Applications
Shan, G
Date: 10 June 2024
Thesis or dissertation
Publisher
University of Exeter
Degree Title
PhD in Engineering
Abstract
To effectively monitor rail infrastructures in real time using wireless sensor networks, an affordable and reliable power supply is in need. While piezoelectric energy harvesting techniques emerge as promising solutions, the current piezoelectric generators designed for railway applications exhibit shortcomings such as low power output, ...
To effectively monitor rail infrastructures in real time using wireless sensor networks, an affordable and reliable power supply is in need. While piezoelectric energy harvesting techniques emerge as promising solutions, the current piezoelectric generators designed for railway applications exhibit shortcomings such as low power output, as well as inadequate durability and robustness. To tackle these challenges, novel piezoelectric vibration energy harvesters have been developed for railway applications in this work, featuring high-performance advancements such as increased power output, dual-frequency capability, and enhanced durability.
Through critical analyses of existing vibration energy harvesters, this research has identified key areas where current piezoelectric technologies require improvements for railway applications. A pioneering energy harvesting mechanism has been conceptualised by combining the frequency up-conversion and piezo stack transducer technologies to augment power generation. Expanding on this, the harvesters have been developed to exhibit dual adjacent vibration modes, achieved through harnessing both longitudinal and torsional oscillations of the designed plate springs within the inertial mass system. This design yields a dual-peak frequency response and a broadened frequency bandwidth. Furthermore, the investigation delves into optimising harvester designs and implementing measures such as pre-stressed technique to increase their durability and robustness. These efforts result in high power output, showcasing a maximum power output of 511 mW and an average power of 24.5 mW under a harmonic excitation of 21 Hz and 0.7 RMS (Root Mean Square) g. Under measured railway vibration signals, the harvester generates a maximum power of 568 mW and an average power of 7.3 mW. The research findings demonstrate that the proposed harvester is capable of generating tens of milliwatts of power, a significant improvement over the hundreds of microwatts produced by existing piezoelectric harvesters in the literature for railway applications.
To protect the energy harvesters from potential overload damage due to the varying and unexpected acceleration levels from railway vibrations, mechanical overload protection strategies for the proposed harvesters are developed in this work. These include innovative stopper designs and impact protection component designs. Following this approach, harvesters incorporating these strategies are further developed for railway applications. The results demonstrate that the harvesters with proposed protection components effectively reduce the acceleration and stress growth rate beyond the excitation threshold. This underscores the effectiveness of these components in shielding the harvesters from unforeseen overload conditions caused by railway vibrations, thereby improving the reliability and durability of the harvesters.
In conclusion, this study advances piezoelectric vibration energy harvesting for railway applications through the design, simulation, fabrication, and testing of novel energy harvesters, which provides practical solutions for enhancing their usability.
Doctoral Theses
Doctoral College
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