A Self-Adaptive and Self-Sufficient Energy Harvesting System

Abstract

Self-adaptive vibration energy harvesters convert the kinetic energy from vibration sources into electrical energy and continuously adapt their resonance frequency to the vibration frequency. Only when the two frequencies match can the system harvest energy efficiently. The harvesting of vibration sources with a time-variant frequency therefore requires self-adaptive vibration harvesting systems without human intervention. This work presents a self-adaptive energy harvesting system that works completely self-sufficiently. Using magnetic forces, the axial load on a bending beam is changed and thus the resonance frequency is set. The system achieves a relative tuning range of 23% at a center frequency of 36.4 Hz. Within this range, the resonance frequency of the harvester can be set continuously and precisely. With a novel optimized method for frequency measurement and with customized electronics, the system only needs 22 µW to monitor the external vibration frequency and is therefore also suitable for environments with low vibration amplitudes. The system was verified on a vibrational test bench and can easily be tailored to a specific vibration source.

Analysis and Characterization of Optimized Dual-Frequency Vibration Energy Harvesters for Low-Power Industrial Applications

“…The same approach was further investigated by Hoffmann et al in [ 35 ], with a smart and power-efficient self-adaptive energy harvesting system which was able to adapt its eigenfrequency to the ambient operating conditions of power units. Furthermore, numerous autonomous self-adaptive and power-efficient energy harvesting systems were introduced in [ 36 , 37 , 38 , 39 ]. Fu et al [ 40 , 41 ] presented and analyzed a broadband rotational energy harvester which uses bistability and frequency up-conversion.…”

Piezoelectric Energy Harvesting Solutions: A Review

“…One of the main characteristics in piezoelectric energy harvesting is the frequency response, since the energy harvesters perform best when their resonance frequency matches their input frequency [ 63 , 126 ]. Currently, most piezoelectric energy harvesters are resonance-based devices; this means that the harvester’s resonant frequency matches the source’s frequency in order to achieve high efficiency [ 127 ].…”

Autonomous Resonance‐Tuning Mechanism for Environmental Adaptive Energy Harvesting

“…To address the resonance tuning problem, researchers have proposed a number of techniques, such as resonance bandwidth broadening and active resonance frequency tuning of the energy harvester. [ 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 ] The easiest way to achieve a wideband resonance frequency is by arraying energy harvesters with graded natural frequencies. [ 17 , 18 , 19 ] However, the energy harvester array exhibits a very low power density because only one energy harvester in the array can operate in the resonance mode at a given frequency.…”

“…[ 24 ] There have also been many studies on electrical active resonance‐tuning technology, in which a sensor detects resonance and a controller adjusts the natural frequency through modulating beam stiffness as applying force by a motor. [ 25 ] It is obvious that all electrical active tuning methods consume additional energy, reducing the net power output. Sometimes, the power required for frequency tuning could be greater than the harvested power.…”