Magnetic Frequency Tuning of a Shape Memory Alloy Thermoelectric Vibration Energy Harvester

Ivo Yotov, Georgi Todorov, Todor Gavrilov and Todor Todorov ()
Additional contact information
Ivo Yotov: Department of Theory of Mechanisms and Machines, Faculty of Industrial Technology, Technical University of Sofia, 1797 Sofia, Bulgaria
Georgi Todorov: Department of Manufacturing Technology and Systems, Faculty of Industrial Technology, Technical University of Sofia, 1797 Sofia, Bulgaria
Todor Gavrilov: Department of Manufacturing Technology and Systems, Faculty of Industrial Technology, Technical University of Sofia, 1797 Sofia, Bulgaria
Todor Todorov: Department of Theory of Mechanisms and Machines, Faculty of Industrial Technology, Technical University of Sofia, 1797 Sofia, Bulgaria

Energies, 2025, vol. 18, issue 13, 1-19

Abstract: This study examines how the frequency of an innovative energy harvester is tuned and how it behaves. This harvester transforms thermal energy into mechanical oscillations of two polyvinylidene fluoride (PVDF) piezoelectric beams, which produce electrical energy via a shape memory alloy (SMA) thread. The oscillation frequency is modified by two magnetic weights that are positioned symmetrically on the SMA thread and interact with stationary NdFeB permanent magnets. The SMA thread shifts laterally due to longitudinal thermal contraction and expansion induced by a constant-temperature heater. Temperature gradients above the heater trigger cyclical variations in the length of the SMA thread, leading to autonomous vibrations of the masses in both the vertical and horizontal planes. An experimental apparatus was constructed to analyze the harvester by tracking the motions of the masses and the voltages produced by the piezoelectric beams. Information was gathered regarding the correlation between output voltage and power with the consumer’s load resistance. These outcomes were confirmed using a multiphysics dynamic simulation that incorporated the interconnections among mechanical, thermal, magnetic, and electrical systems. The findings indicate that the use of permanent magnets increases the bending vibration frequency from 8.3 Hz to 9.2 Hz. For a heater maintained at 70 °C, this boosts the output power from 1.9 µW to 8.18 µW. A notable property of the considered energy harvester configuration is its ability to operate at cryogenic temperatures.

Keywords: frequency tuning; permanent magnet; thermal energy harvesting; vibrations; shape memory alloys; polyvinylidene fluoride (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2025
References: Add references at CitEc
Citations:

Downloads: (external link)
https://www.mdpi.com/1996-1073/18/13/3341/pdf (application/pdf)
https://www.mdpi.com/1996-1073/18/13/3341/ (text/html)

Related works:
This item may be available elsewhere in EconPapers: Search for items with the same title.

Export reference: BibTeX RIS (EndNote, ProCite, RefMan) HTML/Text

Persistent link: https://EconPapers.repec.org/RePEc:gam:jeners:v:18:y:2025:i:13:p:3341-:d:1687418

Access Statistics for this article

Energies is currently edited by Ms. Agatha Cao

More articles in Energies from MDPI
Bibliographic data for series maintained by MDPI Indexing Manager ().