scholarly journals Modeling and Simulation of Linear and Nonlinear MEMS Scale Electromagnetic Energy Harvesters for Random Vibration Environments

2014 ◽  
Vol 2014 ◽  
pp. 1-15 ◽  
Author(s):  
Farid Khan ◽  
Boris Stoeber ◽  
Farrokh Sassani
Keyword(s):  
Resonant Frequency ◽  
Spectral Density ◽  
Output Voltage ◽  
Random Vibration ◽  
Nonlinear Damping ◽  
Electromagnetic Energy ◽  
Mean Square ◽  
Load Voltage ◽  
Energy Harvesters ◽  
Transformation Factor

The simulation results for electromagnetic energy harvesters (EMEHs) under broad band stationary Gaussian random excitations indicate the importance of both a high transformation factor and a high mechanical quality factor to achieve favourable mean power, mean square load voltage, and output spectral density. The optimum load is different for random vibrations and for sinusoidal vibration. Reducing the total damping ratio under band-limited random excitation yields a higher mean square load voltage. Reduced bandwidth resulting from decreased mechanical damping can be compensated by increasing the electrical damping (transformation factor) leading to a higher mean square load voltage and power. Nonlinear EMEHs with a Duffing spring and with linear plus cubic damping are modeled using the method of statistical linearization. These nonlinear EMEHs exhibit approximately linear behaviour under low levels of broadband stationary Gaussian random vibration; however, at higher levels of such excitation the central (resonant) frequency of the spectral density of the output voltage shifts due to the increased nonlinear stiffness and the bandwidth broadens slightly. Nonlinear EMEHs exhibit lower maximum output voltage and central frequency of the spectral density with nonlinear damping compared to linear damping. Stronger nonlinear damping yields broader bandwidths at stable resonant frequency.

scholarly journals Adaptive Electromagnetic Energy Harvester for Mobile Devices

2020 ◽  
Author(s):  
Haziq Kamal ◽  
Peyman Moghadam
Keyword(s):  
Resonant Frequency ◽  
Mobile Devices ◽  
Energy Harvester ◽  
Excitation Frequency ◽  
Electromagnetic Energy ◽  
Major Drawback ◽  
Energy Harvesters ◽  
Limited Effectiveness ◽  
Energy Harvesting Devices ◽  
Ambient Excitation

<div>Advances in design and development of light-weight and low power wearable and mobile devices open up the possibility of lifetime extension of these devices from ambient sources through energy harvesting devices as opposed to periodically recharge the batteries. The most commonly available ambient energy source for mobile devices is Kinetic energy harvesters (KEH). The major drawback of the energy harvesters is limited effectiveness of harvesting mechanism near a fixed resonant frequency. It is difficult to harvest a reliable amount of energy from every forms of device motions with different excitation frequencies. To overcome this drawback, in this paper we propose an adaptive electromagnetic energy harvester which utilises spring characteristics to adapt its resonant frequency to match the ambient excitation frequency. This paper presents a prototype design and analysis of an adaptive electromagnetic energy harvester both in simulation and real. The harvester has tested using a specially designed experimental setup and compared with numerical simulations. The proposed solution generates 3.5 times higher maximum power over the default power output and 2.4 times higher maximum frequency compared to a fixed resonant frequency electromagnetic energy harvester.</div>

scholarly journals Adaptive Electromagnetic Energy Harvester for Mobile Devices

2020 ◽  
Author(s):  
Haziq Kamal ◽  
Peyman Moghadam
Keyword(s):  
Resonant Frequency ◽  
Mobile Devices ◽  
Energy Harvester ◽  
Excitation Frequency ◽  
Electromagnetic Energy ◽  
Major Drawback ◽  
Energy Harvesters ◽  
Limited Effectiveness ◽  
Energy Harvesting Devices ◽  
Ambient Excitation

<div>Advances in design and development of light-weight and low power wearable and mobile devices open up the possibility of lifetime extension of these devices from ambient sources through energy harvesting devices as opposed to periodically recharge the batteries. The most commonly available ambient energy source for mobile devices is Kinetic energy harvesters (KEH). The major drawback of the energy harvesters is limited effectiveness of harvesting mechanism near a fixed resonant frequency. It is difficult to harvest a reliable amount of energy from every forms of device motions with different excitation frequencies. To overcome this drawback, in this paper we propose an adaptive electromagnetic energy harvester which utilises spring characteristics to adapt its resonant frequency to match the ambient excitation frequency. This paper presents a prototype design and analysis of an adaptive electromagnetic energy harvester both in simulation and real. The harvester has tested using a specially designed experimental setup and compared with numerical simulations. The proposed solution generates 3.5 times higher maximum power over the default power output and 2.4 times higher maximum frequency compared to a fixed resonant frequency electromagnetic energy harvester.</div>

Comparing Random Vibration Inputs: Power Spectral Density (PSD) Versus Root Mean-Square Acceleration (Grms)

2003 ◽  
Author(s):  
Ivan Straznicky
Keyword(s):  
Spectral Density ◽  
Root Mean Square ◽  
Power Spectral Density ◽  
Fatigue Damage ◽  
Random Vibration ◽  
Mean Square ◽  
Vibration Effect ◽  
Operating Environments ◽  
Power Spectral ◽  
Magnitude Difference

Many defense programs have vibration requirements for electronics which are often specified as random vibration input. Often, this input is based on measurements taken at the locations of interest for the spectrum of vehicle operating environments. The resulting specification is typically several power spectral density, or PSD, curves with associated durations. The root mean square acceleration, or Grms, can be readily calculated for each PSD curve. Grms values are sometimes used to compare different PSD curves for severity. However, this can be misleading. The impacts of two different random vibration inputs, with the same Grms value, can be very different. By calculating fatigue damage values for various components on a circuit card assembly subjected to these inputs, it can be shown that equal Grms values do not result in equal damage. In fact, there can be two orders of magnitude difference in component damage values. This means that Grms values are very poor indicators of random vibration effect, and should not be used for comparison purposes.

scholarly journals Analysis and Implementation of a Frequency Control DC–DC Converter for Light Electric Vehicle Applications

Electronics ◽  
2021 ◽  
Vol 10 (14) ◽  
pp. 1623
Author(s):  
Bor-Ren Lin
Keyword(s):  
Electric Vehicles ◽  
Output Voltage ◽  
Frequency Control ◽  
Input Voltage ◽  
Pulse Frequency ◽  
Switching Frequency ◽  
Battery Charger ◽  
Dc Microgrid ◽  
Load Voltage ◽  
Transportation Vehicle

In order to realize emission-free solutions and clean transportation alternatives, this paper presents a new DC converter with pulse frequency control for a battery charger in electric vehicles (EVs) or light electric vehicles (LEVs). The circuit configuration includes a resonant tank on the high-voltage side and two variable winding sets on the output side to achieve wide output voltage operation for a universal LEV battery charger. The input terminal of the presented converter is a from DC microgrid with voltage levels of 380, 760, or 1500 V for house, industry plant, or DC transportation vehicle demands, respectively. To reduce voltage stresses on active devices, a cascade circuit structure with less voltage rating on power semiconductors is used on the primary side. Two resonant capacitors were selected on the resonant tank, not only to achieve the two input voltage balance problem but also to realize the resonant operation to control load voltage. By using the variable switching frequency approach to regulate load voltage, active switches are turned on with soft switching operation to improve converter efficiency. In order to achieve wide output voltage capability for universal battery charger demands such as scooters, electric motorbikes, Li-ion e-trikes, golf carts, luxury golf cars, and quad applications, two variable winding sets were selected to have a wide voltage output (50~160 V). Finally, experiments with a 1 kW rated prototype were demonstrated to validate the performance and benefits of presented converter.

A Study and Review of Human Response to Prolonged Random Vibration

1966 ◽  
Vol 8 (6) ◽  
pp. 481-492 ◽  
Author(s):  
Richard J. Hornick ◽  
Norman M. Lefritz
Keyword(s):  
Spectral Density ◽  
High Speed ◽  
Random Vibration ◽  
Human Performance ◽  
Vibration Characteristic ◽  
Human Response ◽  
Human Capabilities ◽  
Power Spectral ◽  
Long Duration ◽  
Low Altitude

This article describes a study conducted to determine the effects of long duration, random vibration—characteristic of low-altitude high-speed (LAHS) flight aircraft—on human performance, physiological, biodynamic, and tolerance responses. Ten subjects experienced 0.10, 0.15, and 0.20 RMS g with a shaped power spectral density from 1 to 12 cps while engaging in LAHS control tasks. Simulation runs were of 5 hours duration, with the centermost 4 hours under dynamic conditions. Results of this experiment are related to those of other studies which had the same general objectives in order to provide a brief review and summary about what is known regarding human capabilities for LAHS flight.

On Modeling of Springless Electromagnetic Energy Harvesters

2020 ◽  
pp. 151-159
Author(s):  
Ramy A. Mohamed ◽  
Ayman El-Badawy ◽  
Ahmed Moustafa ◽  
Andrew Kirolos ◽  
Mostafa Soliman ◽  
...  
Keyword(s):  
Electromagnetic Energy ◽  
Energy Harvesters
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