scholarly journals Resonance frequency tuning in vibration-based energy harvesting systems

2018 ◽  
Author(s):  
Hadi Madinei
Keyword(s):  
Energy Harvesting ◽  
Resonance Frequency ◽  
Frequency Tuning ◽  
Harvesting Systems

scholarly journals A Theory for Energy-Optimized Operation of Self-Adaptive Vibration Energy Harvesting Systems with Passive Frequency Adjustment

Micromachines ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 44 ◽  
Author(s):  
Mario Mösch ◽  
Gerhard Fischerauer
Keyword(s):  
Energy Harvesting ◽  
Resonance Frequency ◽  
Optimal Operation ◽  
Energy Output ◽  
Vibration Energy ◽  
Vibration Energy Harvesting ◽  
Vibration Energy Harvester ◽  
Frequency Adjustment ◽  
Harvesting Systems ◽  
Self Adaptive

Self-adaptive vibration energy harvesting systems vary their resonance frequency automatically to better exploit changing environmental conditions. The energy required for the adjustment is taken from the energy storage of the harvester module. The energy gained by an adjustment step has to exceed the energy expended on it to justify the adjustment. A smart self-adaptive system takes this into account and operates in a manner that maximizes the energy output. This paper presents a theory for the optimal operation of a vibration energy harvester with a passive resonance-frequency adjustment mechanism (one that only requires energy for the adjustment steps proper, but not during the hold phases between the steps). Several vibration scenarios are considered to derive a general guideline. It is shown that there exist conditions under which a narrowing of the adjustment bandwidth improves the system characteristics. The theory is applied to a self-adaptive energy harvesting system based on electromagnetic transduction with narrowband resonators. It is demonstrated that the novel optimum mode of operation increases the energy output by a factor of 3.6.

scholarly journals Recent Advances in Energy Harvesting Technologies for Structural Health Monitoring Applications

2014 ◽  
Vol 2014 ◽  
pp. 1-14 ◽  
Author(s):  
Joseph Davidson ◽  
Changki Mo
Keyword(s):  
Structural Health Monitoring ◽  
Energy Harvesting ◽  
Health Monitoring ◽  
Frequency Tuning ◽  
Piezoelectric Materials ◽  
Local Environment ◽  
Wind Pressure ◽  
Structural Health ◽  
Monitoring Applications ◽  
Harvesting Systems

This paper reviews recent developments in energy harvesting technologies for structural health monitoring applications. Many industries have a great deal of interest in obtaining technology that can be used to monitor the health of machinery and structures. In particular, the need for autonomous monitoring of structures has been ever-increasing in recent years. Autonomous SHM systems typically include embedded sensors, data acquisition, wireless communication, and energy harvesting systems. Among all of these components, this paper focuses on the energy harvesting technologies. Since low-power sensors and wireless communications are used in newer SHM systems, a number of researchers have recently investigated techniques to extract energy from the local environment to power these stand-alone systems. Ambient energy sources include vibration, thermal gradients, solar, wind, pressure, etc. If the structure has a rich enough loading, then it may be possible to extract the needed power directly from the structure itself. Harvesting energy using piezoelectric materials by converting applied stress to electricity is most common. Other methods to harvest energy such as electromagnetic, magnetostrictive, or thermoelectric generator are also reviewed. Lastly, an energy harvester with frequency tuning capability is demonstrated.

Towards a Self-Tunable, Wide Frequency Bandwidth Vibration Energy Harvesting Device

2009 ◽  
Author(s):  
Vinod R. Challa ◽  
M. G. Prasad ◽  
Frank T. Fisher
Keyword(s):  
Energy Harvesting ◽  
Resonance Frequency ◽  
Power Output ◽  
Frequency Tuning ◽  
Cutoff Frequency ◽  
Peak Power Output ◽  
Vibration Energy ◽  
Frequency Bandwidth ◽  
Vibration Energy Harvesting ◽  
Ultra Low Power

Vibration energy harvesting is increasing in popularity due to potential applications such as powering wireless sensors and ultra low power devices. For efficient energy harvesting, matching the device frequency to the source frequency is a major design requirement. Since mechanical vibrations differ in characteristics (frequency and acceleration amplitude), it is difficult to design an individual energy harvesting device for every source. Recently, several groups have pursued techniques to tune the resonance frequency of the vibrating structure through active and passive methods. In this paper, work has been done to attain a self-tunable energy harvesting device, which utilizes a magnetic force resonance frequency tuning technique to tune the device. The device is successfully tuned with in a bandwidth of ± 27% of its untuned resonance frequency, considering root mean square of the peak power output as the cutoff for frequency bandwidth. Since the technique is semi-active, energy is only consumed to tune the resonance frequency and is not required to remain at that specific frequency. The device consists of a piezoelectric cantilever beam array which is displaced to the desired distance to induce magnetic stiffness and to match the source frequency using a DC motor. The device has a power output of approximately 0.7 mW to 1 mW in the designed cutoff frequency range. The amount of energy consumed by the actuator to displace the beam is approximately 3.5 W to 4.5 W, which requires approximately 150 minutes to reclaim the expended energy.

Improved Adjusting Capacitor Method for Piezoelectric Frequency Tuning and Maximum Energy Harvesting

2014 ◽  
Author(s):  
Murtadha A. AL Maliki ◽  
Karla M. Mossi
Keyword(s):  
Energy Harvesting ◽  
Resonance Frequency ◽  
Frequency Tuning ◽  
Electrical Energy ◽  
Load Resistance ◽  
Maximum Power ◽  
Ambient Vibration ◽  
Passive Element ◽  
Power Extraction ◽  
Shunt Capacitor

Energy harvesting refers to conversion of ambient energy into electrical energy. A typical way to accomplish this conversion is through the use of a piezoelectric harvester. This device produces a maximum power when its natural resonance frequency matches that of the ambient vibration. This property is the main limitation to developing many application. To address this restriction, it has been proposed by several investigators that a capacitor be connected in parallel to a piezoelectric cantilever as a method of electrical tuning. When such passive element is connected, the power decreases from its original value. In this paper an improvement to this approach is proposed. Once the tuning capacitor is connected, an inductor value is chosen such that conjugate impedance matching becomes reasonable and plugging this component can give an improvement for both the voltage and power generated. Capacitors of 0.2 μF to 1.5μF values were connected in parallel to a piezoelectric unimorph Type TH-7R with an inherent capacitance of 166 nF and a 208 Hz resonance frequency to develop a tuning range of four Hz. The harvested power during the tuning was proved to be correlated inversely to the shunt capacitor value. By connecting a 700 mH and 2 H inductors in parallel to the system, a significant improvement in power was obtained. In addition, a correlation between the resonance frequency and optimal load resistance with the shunt capacitor value has been studied. The results show that this innovative method is an efficient method for frequency tuning and maximum power extraction.

A Vibration Energy Harvesting Structure, Tunable Over a Wide Frequency Range Using Minimal Actuation

2013 ◽  
Author(s):  
John Heit ◽  
David Christensen ◽  
Shad Roundy
Keyword(s):  
Energy Harvesting ◽  
Resonance Frequency ◽  
Frequency Tuning ◽  
Wide Frequency Range ◽  
Design Parameters ◽  
Vibration Energy ◽  
Test Results ◽  
Vibration Energy Harvesting ◽  
Frequency Tunability ◽  
Added Benefit

This paper introduces a novel vibration energy harvesting structure with a resonance frequency that is tunable over a large range using a simple compact mechanical adjustment that alters the structural stiffness. The frequency tuning requires minimal actuation that can be “turned off” while maintaining the new resonance frequency. Testing shows that the natural frequency can be adjusted from 32 Hz to 85 Hz. The structure is coupled with an electromagnetic transducer to generate power. Test results at varying excitation frequencies and amplitudes demonstrate tunable power generation over a very wide bandwidth. In addition to frequency tunability, the structure is a nonlinear softening spring, which provides the added benefit of a passively wider bandwidth for specific ranges of the design parameters.

Analysis of magneto rheological elastomers for energy harvesting systems

2020 ◽  
Vol 64 (1-4) ◽  
pp. 439-446
Author(s):  
Gildas Diguet ◽  
Gael Sebald ◽  
Masami Nakano ◽  
Mickaël Lallart ◽  
Jean-Yves Cavaillé
Keyword(s):  
Magnetic Field ◽  
Energy Harvesting ◽  
Shear Strain ◽  
Magnetic Induction ◽  
Magnetic Particles ◽  
Homogeneous Magnetic Field ◽  
Electrical Signal ◽  
Harvesting Systems ◽  
Dc Bias ◽  
Magneto Rheological

Magneto Rheological Elastomers (MREs) are composite materials based on an elastomer filled by magnetic particles. Anisotropic MRE can be easily manufactured by curing the material under homogeneous magnetic field which creates column of particles. The magnetic and elastic properties are actually coupled making these MREs suitable for energy conversion. From these remarkable properties, an energy harvesting device is considered through the application of a DC bias magnetic induction on two MREs as a metal piece is applying an AC shear strain on them. Such strain therefore changes the permeabilities of the elastomers, hence generating an AC magnetic induction which can be converted into AC electrical signal with the help of a coil. The device is simulated with a Finite Element Method software to examine the effect of the MRE parameters, the DC bias magnetic induction and applied shear strain (amplitude and frequency) on the resulting electrical signal.

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