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Measuring the Parameters of Piezo Energy Harvesters
Kunz, Jan ; Novák,, Martin (referee) ; Hadaš, Zdeněk (referee) ; Beneš, Petr (advisor)
This dissertation deals with the measurement of piezoenergy harvester parameters, in particular the measurement of their efficiency. The first part of the thesis summarizes important metrics for their comparison and reviews existing measurement systems for measuring harvester performance parameters. The measurement of harvester efficiency is simplified due to the complexity of power measurement and harvester efficiency is calculated from its parameters. However, this method is not accurate because it neglects mechanical losses and has a large measurement uncertainty. For this reason, the main objective of this work is to find a way to directly measure the harvester power input and thus measure its efficiency by definition, i.e. including mechanical losses. By analyzing the power flow in the harvester power chain, a way to achieve this goal has been found. Then, I have created an automated measurement system that allows to measure the harvester power parameters and also its efficiency including the determination of measurement uncertainties. In the last section, the performance, parameters and especially the two types of efficiency for commercially available harvesters are compared. As expected, the efficiency evaluated according to the definition come out smaller than in the case of its simplified version. However, this ratio varies widely for different harvester types, with the new efficiency being approximately one-third for PZT harvesters but only one-hundredth for PVDF harvesters. This significant difference shows that the different types of harvesters have large differences in mechanical losses, this difference could not be measured until now and thus remained neglected.
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Measuring the Parameters of Piezo Energy Harvesters
Kunz, Jan ; Novák,, Martin (referee) ; Hadaš, Zdeněk (referee) ; Beneš, Petr (advisor)
This dissertation deals with the measurement of piezoenergy harvester parameters, in particular the measurement of their efficiency. The first part of the thesis summarizes important metrics for their comparison and reviews existing measurement systems for measuring harvester performance parameters. The measurement of harvester efficiency is simplified due to the complexity of power measurement and harvester efficiency is calculated from its parameters. However, this method is not accurate because it neglects mechanical losses and has a large measurement uncertainty. For this reason, the main objective of this work is to find a way to directly measure the harvester power input and thus measure its efficiency by definition, i.e. including mechanical losses. By analyzing the power flow in the harvester power chain, a way to achieve this goal has been found. Then, I have created an automated measurement system that allows to measure the harvester power parameters and also its efficiency including the determination of measurement uncertainties. In the last section, the performance, parameters and especially the two types of efficiency for commercially available harvesters are compared. As expected, the efficiency evaluated according to the definition come out smaller than in the case of its simplified version. However, this ratio varies widely for different harvester types, with the new efficiency being approximately one-third for PZT harvesters but only one-hundredth for PVDF harvesters. This significant difference shows that the different types of harvesters have large differences in mechanical losses, this difference could not be measured until now and thus remained neglected.
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