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Modelos de previsão do tempo de vida de dispositivos de armazenamento de energia
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Abstract(s)
Os ensaios acelerados de vida são um método que visa simular as condições de uso e desgaste ao longo do tempo num curto período. Permitem que os fabricantes identifiquem potenciais problemas de desempenho, falhas ou degradação precoce no processo de desenvolvimento, o que leva a melhorias na qualidade e fiabilidade do produto. A presente dissertação tem como principal objetivo a definição do tempo de vida de dispositivos de armazenamento de energia, recorrendo ao envelhecimento acelerado de protótipos de supercondensadores, através de ensaios acelerados de vida. É feita uma introdução completa ao tema dos ensaios acelerados de vida e como estes se apresentam na área da fiabilidade e da estatística, e também a um tema cada vez mais emergente no panorama atual português e mundial, que são as energias renováveis e as tecnologias de armazenamento de energia. Para verificar e implementar os conceitos apresentados, no caso de estudo foram realizados ensaios a protótipos de supercondensadores onde foram expostos a várias tensões superiores à de uso normal, visando acelerar a degradação dos mesmos, até se alcançar a falha. O objetivo da realização destes ensaios passou por prever o tempo de vida destes dispositivos em condições normais de utilização, através da extrapolação de dados a um nível de envelhecimento acelerado. Os dados relativos aos ensaios do caso de estudo foram obtidos através da realização de ensaios acelerados designados como floating tests e depois ajustados a um modelo de degradação adequado. De seguida foram analisados e tratados recorrendo a um software que permitiu obter dados acerca da vida destes componentes, prevendo assim o seu tempo de vida útil a um nível de utilização normal e validando assim a vertente teórica demonstrada no Capítulo 4. Com base nos ensaios realizados e da análise feita aos dados, concluiu-se que existe uma redução gradual do tempo até à falha dos dispositivos, à medida que é imposta uma tensão crescente. Notou-se também que existe um intervalo de valores de tensão onde a degradação dos dispositivos evolui exponencialmente até alcançar a falha, indiciando assim um possível fenómeno de degaste acelerado nessa gama de valores.
Abstract Accelerated life tests are a method that simulates user conditions and wear during time, in a short period of time. They allow manufacturers to identify potential performance issues, failures or early degradation in the development process, which lead to improvements in product quality and reliability. The main objective of this dissertation is to define the lifetime of energy storing devices by accelerating the aging of supercapacitor prototypes, through accelerated life testing. A complete introduction is made regarding accelerated life tests and how they present themselves in reliability and statistics, and to an increasingly emerging topic in the current national and global panorama, which are renewable energies and energy storage technologies. To validate and implement the presented concepts, tests were conducted on supercapacitor prototypes. These prototypes were subjected to various voltages, exceeding normal operating levels, to accelerate their degradation and induce failure. The purpose of these tests was to predict the lifespan of the devices under normal operating conditions by extrapolating data obtained during the accelerated ageing. The experimental data collected in the case study was obtained by carrying out tests called floating test and then they were fitted to an appropriate degradation model and analysed using specialized software. This analysis yielded critical information about the lifespan of these devices, enabling the prediction of their useful life under normal operating conditions and validating the theoretical concepts presented in Chapter 4. Based on the tests and on the data analysis, it was concluded that there is a gradual reduction in the time until failure of the devices, as increasing voltage is imposed. It was also noted that there is a range of voltage values where the degradation of the devices evolves exponentially until failure is reached, thus indicating a possible phenomenon of accelerated wear in that range of values.
Abstract Accelerated life tests are a method that simulates user conditions and wear during time, in a short period of time. They allow manufacturers to identify potential performance issues, failures or early degradation in the development process, which lead to improvements in product quality and reliability. The main objective of this dissertation is to define the lifetime of energy storing devices by accelerating the aging of supercapacitor prototypes, through accelerated life testing. A complete introduction is made regarding accelerated life tests and how they present themselves in reliability and statistics, and to an increasingly emerging topic in the current national and global panorama, which are renewable energies and energy storage technologies. To validate and implement the presented concepts, tests were conducted on supercapacitor prototypes. These prototypes were subjected to various voltages, exceeding normal operating levels, to accelerate their degradation and induce failure. The purpose of these tests was to predict the lifespan of the devices under normal operating conditions by extrapolating data obtained during the accelerated ageing. The experimental data collected in the case study was obtained by carrying out tests called floating test and then they were fitted to an appropriate degradation model and analysed using specialized software. This analysis yielded critical information about the lifespan of these devices, enabling the prediction of their useful life under normal operating conditions and validating the theoretical concepts presented in Chapter 4. Based on the tests and on the data analysis, it was concluded that there is a gradual reduction in the time until failure of the devices, as increasing voltage is imposed. It was also noted that there is a range of voltage values where the degradation of the devices evolves exponentially until failure is reached, thus indicating a possible phenomenon of accelerated wear in that range of values.
Description
Dissertação para obtenção do grau de Mestre em Engenharia Mecânica, na Área de Especialização de Manutenção e Produção
Keywords
Transição energética Produção e armazenamento de energia Envelhecimento acelerado Fiabilidade Tempo médio de vida Energy transition Energy production and storage Accelerated aging Reliability Prototype Mean useful life
Citation
ROQUE, Rodrigo Valente – Modelos de previsão do tempo de vida de dispositivos de armazenamento de energia. Lisboa: Instituto Superior de Engenharia de Lisboa. 2024. Dissertação de Mestrado.