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Article

A New Method to Perform Direct Efficiency Measurement and Power Flow Analysis in Vibration Energy Harvesters

1
Department of Control and Instrumentation, Faculty of Electrical Engineering and Communications, Brno University of Technology, Technicka 3082/12, 616 00 Brno, Czech Republic
2
CEITEC—Central European Institute of Technology, Brno University of Technology, Purkynova 656/123, 612 00 Brno, Czech Republic
*
Author to whom correspondence should be addressed.
Academic Editor: Amir H. Alavi
Sensors 2021, 21(7), 2388; https://doi.org/10.3390/s21072388
Received: 5 March 2021 / Revised: 25 March 2021 / Accepted: 25 March 2021 / Published: 30 March 2021
(This article belongs to the Special Issue Vibration Energy Harvesting for Wireless Sensors)
Measuring the efficiency of piezo energy harvesters (PEHs) according to the definition constitutes a challenging task. The power consumption is often established in a simplified manner, by ignoring the mechanical losses and focusing exclusively on the mechanical power of the PEH. Generally, the input power is calculated from the PEH’s parameters. To improve the procedure, we have designed a method exploiting a measurement system that can directly establish the definition-based efficiency for different vibration amplitudes, frequencies, and resistance loads. Importantly, the parameters of the PEH need not be known. The input power is determined from the vibration source; therefore, the method is suitable for comparing different types of PEHs. The novel system exhibits a combined absolute uncertainty of less than 0.5% and allows quantifying the losses. The approach was tested with two commercially available PEHs, namely, a lead zirconate titanate (PZT) MIDE PPA-1011 and a polyvinylidene fluoride (PVDF) TE LDTM-028K. To facilitate comparison with the proposed efficiency, we calculated and measured the quantity also by using one of the standard options (simplified efficiency). The standard concept yields higher values, especially in PVDFs. The difference arises from the device’s low stiffness, which produces high displacement that is proportional to the losses. Simultaneously, the insufficient stiffness markedly reduces the PEH’s mechanical power. This effect cannot be detected via the standard techniques. We identified the main sources of loss in the damping of the movement by the surrounding air and thermal losses. The latter source is caused by internal and interlayer friction. View Full-Text
Keywords: piezoelectric; piezoelectric ceramic; lead zirconate titanate (PZT); polyvinylidene fluoride (PVDF); energy harvesting; efficiency; efficiency measurement; power conversion; power flow piezoelectric; piezoelectric ceramic; lead zirconate titanate (PZT); polyvinylidene fluoride (PVDF); energy harvesting; efficiency; efficiency measurement; power conversion; power flow
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MDPI and ACS Style

Kunz, J.; Fialka, J.; Pikula, S.; Benes, P.; Krejci, J.; Klusacek, S.; Havranek, Z. A New Method to Perform Direct Efficiency Measurement and Power Flow Analysis in Vibration Energy Harvesters. Sensors 2021, 21, 2388. https://doi.org/10.3390/s21072388

AMA Style

Kunz J, Fialka J, Pikula S, Benes P, Krejci J, Klusacek S, Havranek Z. A New Method to Perform Direct Efficiency Measurement and Power Flow Analysis in Vibration Energy Harvesters. Sensors. 2021; 21(7):2388. https://doi.org/10.3390/s21072388

Chicago/Turabian Style

Kunz, Jan, Jiri Fialka, Stanislav Pikula, Petr Benes, Jakub Krejci, Stanislav Klusacek, and Zdenek Havranek. 2021. "A New Method to Perform Direct Efficiency Measurement and Power Flow Analysis in Vibration Energy Harvesters" Sensors 21, no. 7: 2388. https://doi.org/10.3390/s21072388

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