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.

Analysis of Magnetic Forces in Two-Dimensional Space With Applications for the Tuning of Vibration Energy Harvesting Devices

2015 ◽  
Author(s):  
Lin Dong ◽  
Frank T. Fisher
Keyword(s):  
Energy Harvesting ◽  
Frequency Tuning ◽  
Dimensional Space ◽  
Electrical Energy ◽  
Ambient Vibration ◽  
Two Dimensional ◽  
Vibration Energy Harvesting ◽  
Resonant Frequencies ◽  
Magnetic Forces ◽  
Energy Harvesting Devices

Vibration-based energy harvesting is a process by which ambient vibrations are converted to electrical energy, and is of interest for supplementing or replacing the batteries of individual nodes comprising wireless sensor networks among other applications. Generally, it is desired to match the resonant frequencies of the device with the primary ambient vibration frequencies for optimal energy harvesting performance. While previous work has demonstrated the use of magnetic forces to tune the resonant frequencies of vibrating energy harvesting structures, such efforts have been limited to one-dimensional analyzes. Here frequency tuning is realized by applying magnetic forces to the device in two-dimensional space, such that the resulting magnetic force has both horizontal and vertical components. In the case of a cantilever beam, the transverse force contributes to the transverse stiffness of the system while the axial force contributes to a change in the geometric stiffness of the beam. The effective resonant frequency of the device is then a function of the contributions of the original stiffness of the beam and the two additional stiffness components introduced by the presence of the magnet in 2D space. The simulation results from a COMSOL magnetostatics 3D model agree well with an analytical model describing the magnetic forces between the magnets as a function of location. Such 2D magnetic stiffness tuning approaches may be useful in applications where space constraints impact the available design space of the energy harvester.

scholarly journals Practical Maximum-Power Extraction in Single Microbial Fuel Cell by Effective Delivery through Power Management System

Energies ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 2312
Author(s):  
Jeongjin Yeo ◽  
Taeyoung Kim ◽  
Jae Jang ◽  
Yoonseok Yang
Keyword(s):  
Fuel Cell ◽  
Microbial Fuel Cell ◽  
Power Management ◽  
Operation Time ◽  
Electrical Energy ◽  
Maximum Power ◽  
Extraction Technology ◽  
Power Extraction ◽  
Point Tracking ◽  
Power Point

Power management systems (PMSs) are essential for the practical use of microbial fuel cell (MFC) technology, as they replace the unstable stacking of MFCs with step-up voltage conversion. Maximum-power extraction technology could improve the power output of MFCs; however, owing to the power consumption of the PMS operation, the maximum-power extraction point cannot deliver maximum power to the application load. This study proposes a practical power extraction for single MFCs, which reserves more electrical energy for an application load than conventional maximum power-point tracking (MPPT). When experimentally validated on a real MFC, the proposed method delivered higher output power during a longer PMS operation time than MPPT. The maximum power delivery enables more effective power conditioning of various micro-energy harvesting systems.

Analytical Electromechanical Model of Cantilevered Bi-Stable Composites for Broadband Energy Harvesting

2013 ◽  
Author(s):  
Andres F. Arrieta ◽  
Tommaso Delpero ◽  
Paolo Ermanni
Keyword(s):  
Energy Harvesting ◽  
Large Amplitude ◽  
Wide Band ◽  
Electrical Energy ◽  
Ambient Vibration ◽  
Mode Shapes ◽  
Rapid Reduction ◽  
Electromechanical Model ◽  
Response Characteristics ◽  
Good Agreement

Vibration based energy harvesting has received extensive attention in the engineering community for the past decade thanks to its potential for autonomous powering small electronic devices. For this purpose, linear electromechanical devices converting mechanical to useful electrical energy have been extensively investigated. Such systems operate optimally when excited close to or at resonance, however, for these lightly damped structures small variations in the ambient vibration frequency results in a rapid reduction of performance. The idea to use nonlinearity to obtain large amplitude response in a wider frequency range, has shown the potential for achieving so called broadband energy harvesting. An interesting type of nonlinear structures exhibiting the desired broadband response characteristics are bi-stable composites. The bi-stable nature of these composites allows for designing several ranges of wide band large amplitude oscillations, from which high power can be harvested. In this paper, an analytical electromechanical model of cantilevered piezoelectric bi-stable composites for broadband harvesting is presented. The model allows to calculate the modal characteristics, such as natural frequencies and mode shapes, providing a tool for the design of bi-stable composites as harvesting devices. The generalised coupling coefficient is used to select the positioning of piezoelectric elements on the composites for maximising the conversion energy. The modal response of a test specimen is obtained and compared to theoretical results showing good agreement, thus validating the model.

Topology Optimization of Piezoelectric Energy Harvesting Devices Subjected to Stochastic Excitation

2010 ◽  
Author(s):  
Zheqi Lin ◽  
Hae Chang Gea ◽  
Shutian Liu
Keyword(s):  
Topology Optimization ◽  
Energy Harvesting ◽  
Electrical Energy ◽  
Ambient Vibration ◽  
Piezoelectric Energy Harvesting ◽  
The Past ◽  
Piezoelectric Energy ◽  
Random Responses ◽  
Pseudo Excitation ◽  
Energy Harvesting Devices

Converting ambient vibration energy into electrical energy using piezoelectric energy harvester has attracted much interest in the past decades. In this paper, topology optimization is applied to design the optimal layout of the piezoelectric energy harvesting devices. The objective function is defined as to maximize the energy harvesting performance over a range of ambient vibration frequencies. Pseudo excitation method (PEM) is applied to analyze structural stationary random responses. Sensitivity analysis is derived by the adjoint method. Numerical examples are presented to demonstrate the validity of the proposed approach.

Resonant Frequency Tuning Strategies for Vibration-Based Energy Harvesters

2017 ◽  
Author(s):  
Lin Dong ◽  
Frank T. Fisher
Keyword(s):  
Energy Harvesting ◽  
Resonant Frequency ◽  
Energy Harvester ◽  
Frequency Tuning ◽  
Electrical Energy ◽  
Mechanical Stretch ◽  
Applied Bias Voltage ◽  
Energy Harvesters ◽  
Frequency Matching ◽  
Low Levels

Vibration-based energy harvesting has been widely investigated to as a means to generate low levels of electrical energy for applications such as wireless sensor networks. However, due to the fact that vibration from the environment is typically random and varies with different magnitudes and frequencies, it is a challenge to implement frequency matching in order to maximize the power output of the energy harvester with a wider frequency bandwidth for applications where there is a time-dependent, varying source frequency. Possible solutions of frequency matching include widening the bandwidth of the energy harvesters themselves in order to implement frequency matching and to perform resonance-based tuning approach, the latter of which shows the most promise to implement a frequency matching design. Here three tuning strategies are discussed. First a two-dimensional resonant frequency tuning technique for the cantilever-geometry energy harvesting device which extended previous 1D tuning approaches was developed. This 2D approach could be used in applications where space constraints impact the available design space of the energy harvester. In addition, two novel resonant frequency tuning approaches (tuning via mechanical stretch and tuning via applied bias voltage, respectively) for electroactive polymer (EAP) membrane-based geometry energy harvesters was proposed, such that the resulting changes in membrane tension were used to tune the device for applications targeting variable ambient frequency environments.

Comparative Study of Two Different Converters with its Controller for Grid Connected WECS with PMSG

2019 ◽  
Vol 8 (2) ◽  
pp. 1-24
Author(s):  
Sasmita Behera ◽  
Matruprasad Jyotiranjan
Keyword(s):  
Power Quality ◽  
Pulse Width Modulation ◽  
Harmonic Distortion ◽  
Synchronous Generator ◽  
Electrical Energy ◽  
Maximum Power ◽  
Multilevel Inverter ◽  
Resistive Load ◽  
Power Extraction ◽  
Point Tracking

Wind is a source for generating clean and economical electrical energy with a proper harnessing mechanism. For a wind energy conversion system (WECS), maximum power extraction with optimum power quality is required. In this article, the grid power quality is enhanced, using a multilevel inverter which provides smoother and pure sinusoidal waves as compared to two-level inverter by decreasing total harmonic distortion (THD) in WECS with a permanent magnet synchronous generator (PMSG). Also, a maximum power point tracking (MPPT) algorithm is based on an optimal torque controller, employed to extract more power. In this study, a WECS with a PMSG connected to the local linear resistive load and grid is considered for simulation. A multilevel inverter grid interface is controlled by in phase disposition pulse width modulation (IPD – PWM). The multilevel inverter with MPPT has been acknowledged as superior to a normal two-level inverter without MPPT Controller. Simulation results as observed for fixed and variable wind speed including MPPT demonstrate benefits of the proposed method.

On the performance of a dual-mode non-linear vibration energy harvesting device

2012 ◽  
Vol 23 (13) ◽  
pp. 1423-1432 ◽  
Author(s):  
Roszaidi Ramlan ◽  
Michael J Brennan ◽  
Brian R Mace ◽  
Stephen G Burrow
Keyword(s):  
Energy Harvesting ◽  
Maximum Power ◽  
Ambient Vibration ◽  
Research Trend ◽  
Iron Core ◽  
Dual Mode ◽  
Vibration Energy Harvesting ◽  
Stable Mode ◽  
Linear Generator ◽  
Non Linear

The research trend for harvesting energy from the ambient vibration sources has moved from using a linear resonant generator to a non-linear generator in order to improve on the performance of a linear generator; for example, the relatively small bandwidth, intolerance to mistune and the suitability of the device for low-frequency applications. This article presents experimental results to illustrate the dynamic behaviour of a dual-mode non-linear energy-harvesting device operating in hardening and bi-stable modes under harmonic excitation. The device is able to change from one mode to another by altering the negative magnetic stiffness by adjusting the separation gap between the magnets and the iron core. Results for the device operating in both modes are presented. They show that there is a larger bandwidth for the device operating in the hardening mode compared to the equivalent linear device. However, the maximum power transfer theory is less applicable for the hardening mode due to occurrence of the maximum power at different frequencies, which depends on the non-linearity and the damping in the system. The results for the bi-stable mode show that the device is insensitive to a range of excitation frequencies depending upon the input level, damping and non-linearity.

Energy Harvesting Characteristics of Conical Shells

2011 ◽  
Author(s):  
H. Li ◽  
S. D. Hu ◽  
H. S. Tzou
Keyword(s):  
Energy Harvesting ◽  
Conical Shell ◽  
Energy Harvester ◽  
Electric Energy ◽  
Electrical Energy ◽  
Open Circuit ◽  
Ambient Vibration ◽  
Circular Membrane ◽  
Shell Surface ◽  
Piezoelectric Energy

Piezoelectric energy harvesting has experienced significant growth over the past few years. Various harvesting structures have been proposed to convert ambient vibration energies to electrical energy. However, these harvester’s base structures are mostly beams and some plates. Shells have great potential to harvest more energy. This study aims to evaluate a piezoelectric coupled conical shell based energy harvester system. Piezoelectric patches are laminated on the conical shell surface to convert vibration energy to electric energy. An open-circuit output voltage of the conical energy harvester is derived based on the thin-shell theory and the Donnel-Mushtari-Valsov theory. The open-circuit voltage and its derived energy consists of four components respectively resulting from the meridional and circular membrane strains, as well as the meridional and circular bending strains. Reducing the surface of the harvester to infinite small gives the spatial energy distribution on the shell surface. Then, the distributed modal energy harvesting characteristics of the proposed PVDF/conical shell harvester are evaluated in case studies. The results show that, for each mode with unit modal amplitude, the distribution depends on the mode shape, harvester location, and geometric parameters. The regions with high strain outputs yield higher modal energies. Accordingly, optimal locations for the PVDF harvester can be defined. Also, when modal amplitudes are specified, the overall energy of the conical shell harvester can be calculated.

Piezoelectric wind energy harvester for low-power sensors

2011 ◽  
Vol 22 (18) ◽  
pp. 2215-2228 ◽  
Author(s):  
Jayant Sirohi ◽  
Rohan Mahadik
Keyword(s):  
Energy Harvesting ◽  
Wind Energy ◽  
Mechanical Energy ◽  
Electrical Energy ◽  
Load Resistance ◽  
Operating Conditions ◽  
Sensor Nodes ◽  
Wireless Sensor ◽  
Wireless Sensor Nodes ◽  
Piezoelectric Energy

There has been increasing interest in wireless sensor networks for a variety of outdoor applications including structural health monitoring and environmental monitoring. Replacement of batteries that power the nodes in these networks is maintenance intensive. A wind energy–harvesting device is proposed as an alternate power source for these wireless sensor nodes. The device is based on the galloping of a bar with triangular cross section attached to a cantilever beam. Piezoelectric sheets bonded to the beam convert the mechanical energy into electrical energy. A prototype device of size approximately 160 × 250 mm was fabricated and tested over a range of operating conditions in a wind tunnel, and the power dissipated across a load resistance was measured. A maximum power output of 53 mW was measured at a wind velocity of 11.6 mph. An analytical model incorporating the coupled electromechanical behavior of the piezoelectric sheets and quasi-steady aerodynamics was developed. The model showed good correlation with measurements, and it was concluded that a refined aerodynamic model may need to include apparent mass effects for more accurate predictions. The galloping piezoelectric energy-harvesting device has been shown to be a viable option for powering wireless sensor nodes in outdoor applications.

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