Optimum resistive loads for vibration-based electromagnetic energy harvesters with a stiffening nonlinearity

Cammarano, Andrea; Neild, Simon A; Burrow, Steve G; Wagg, DJ; Inman, Daniel J.

doi:10.1177/1045389x14523854

Cited by 38 publications

(39 citation statements)

References 28 publications

(39 reference statements)

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“…The analysis of the energy harvester often involves determining the power transferred to the electrical load and the optimal load condition. Due to the complexity of nonlinear behaviours, the analysis can be achieved with the following simplifications [36,37]:…”

Section: Magnetically Levitated Harvestermentioning

confidence: 99%

Temperature dependence of a magnetically levitated electromagnetic vibration energy harvester

Pancharoen

Zhu

Beeby

2017

Sensors and Actuators A: Physical

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This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Abstract Electromagnetic vibration energy harvesters including magnetically levitated devices where opposing magnets are used to form the spring have been well documented. The strength of the magnets naturally has a large influence on the dynamic characteristics and output power of such harvesters. However, it can be affected by ambient temperatures which vary from applications to applications. This paper presents investigation into the performance of a magnetically levitated electromagnetic energy harvester under various ambient temperatures. Parameters investigated include magnetic flux density, resonant frequency, damping ratio, open circuit output voltage, velocity of the relative motion and the load resistance. Both simulation and experimental results show that these properties vary with ambient temperatures. The magnetic flux density reduces as the temperature increases which results in lower resonant frequency, lower relative velocity, lower open circuit output voltage and higher damping ratio. Varying resonant frequencies with temperature can lead to harvesters being de-tuned from the target vibration frequency. Decreasing magnetic field strength and increased damping ratios will also reduce output power even if the harvester's resonant frequency still matches the environmental vibration frequency. The power transferred to the electrical load will be reduced due to the variation in the optimal load resistance with temperature. This means the harvester is no longer matched to achieve the maximum harvested power. The specified maximum operating temperature of the magnets was found to lead to partial demagnetisation. When cycling from room to the maximum specified temperature, the magnetic field was initially found to fall but remained constant thereafter. Harvesters were found to operate beyond the specified maximum operating temperature of the magnet, but suffer from a reduced magnetic strength.

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Section: Magnetically Levitated Harvestermentioning

confidence: 99%

Temperature dependence of a magnetically levitated electromagnetic vibration energy harvester

Pancharoen

Zhu

Beeby

2017

Sensors and Actuators A: Physical

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“…The work presented here builds on the findings of [19]. In [19] it has been demonstrated that under optimal conditions a nonlinear energy harvester can deliver as much power as a linear harvester to a purely resistive load.…”

Section: Introductionmentioning

confidence: 98%

“…In [19] it has been demonstrated that under optimal conditions a nonlinear energy harvester can deliver as much power as a linear harvester to a purely resistive load. For this to be achieved both the resistive load and the underlying linear frequency ω n must be selected carefully.…”

Section: Introductionmentioning

confidence: 99%

“…Cammarano et al [19] addressed the problem of how these compare with linear devices and how to optimize the electrical load and the mechanical characteristics.…”

Section: Introductionmentioning

confidence: 99%

“…Answering this question, using the optimization technique developed in [19], allows us to assess when the use of a nonlinear harvester is potentially more beneficial than a linear one. In section 2 the definition of linear and nonlinear bandwidth is provided and the effect of the mechanical parameter of the harvester on the bandwidth is shown.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

The bandwidth of optimized nonlinear vibration-based energy harvesters

Cammarano

Neild

Burrow

et al. 2014

Smart Mater. Struct.

Self Cite

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In an attempt to improve the performance of vibration-based energy harvesters, many authors suggest that nonlinearities can be exploited to increase the bandwidths of linear devices. Nevertheless, the complex dependence of the response upon the input excitation has made a realistic comparison of linear harvesters with nonlinear energy harvesters challenging. In a previous work it has been demonstrated that for a given frequency of excitation, it is possible to achieve the same maximum power for a nonlinear harvester as that for a linear harvester, provided that the resistance and the linear stiffness of both are optimized. This work focuses on the bandwidths of linear and nonlinear harvesters and shows which device is more suitable for harvesting energy from vibrations. The work considers different levels of excitation as well as different frequencies of excitation. In addition, the effect of the mechanical damping of the oscillator on the power bandwidth is shown for both the linear and nonlinear cases.

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Relating Backbone Curves to the Forced Responses of Nonlinear Systems

Hill

Cammarano

Neild

et al. 2016

Nonlinear Dynamics, Volume 1

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Backbone curves describe the steady-state responses of unforced, undamped systems, therefore they do not directly relate to any specific forcing and damping configuration. Nevertheless, they can be used to understand the underlying dynamics of nonlinear systems subjected to forcing and damping. Building on this concept, in this paper we describe an analytical technique used to predict the onset of internally-resonant modal interactions in an example system. In conjunction with backbone curve analysis, which can be used to predict the possibility of internally-resonant behaviour, this approach provides an analytical tool for understanding and quantifying internally-resonant regions in the forced responses.

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Optimum resistive loads for vibration-based electromagnetic energy harvesters with a stiffening nonlinearity

Cited by 38 publications

References 28 publications

Temperature dependence of a magnetically levitated electromagnetic vibration energy harvester

Temperature dependence of a magnetically levitated electromagnetic vibration energy harvester

The bandwidth of optimized nonlinear vibration-based energy harvesters

Relating Backbone Curves to the Forced Responses of Nonlinear Systems

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