Towards Optimizing DC Loads for Power Generation From Arbitrarily Excited Nonlinear Vibration Energy Harvesters

Author(s):  
Quanqi Dai ◽  
Ryan L. Harne

In order to effectively take advantage of stiffness nonlinearities in vibration energy harvesters, the harvesters must be appropriately designed to ensure optimum direct current (DC) power generation. Yet, such optimization has only previously been investigated for alternating current (AC) power generation although most electronics demand DC power for their functioning. Moreover, real world excitations contain stochastic contributions combined with periodic components that challenges conventional approaches of investigation that only give attention to the harmonic excitation parts. To fill in the knowledge gap, this research undertakes comprehensive simulations to begin formulating conclusive understanding on the relationships between rectified power generation and nonlinear energy harvester system characteristics when the platforms are subjected to realistic combinations of harmonic and stochastic excitations. According to the simulation results, the rectified power demonstrates clear dependence on the load resistance in the unique limiting cases of complete or no stochastic excitation. When the excitation vibrations include both harmonic and stochastic components, the optimal resistance to maximize DC power exhibits a smoothly correlated but nonlinear change between the limiting case values of the resistance. The results of this investigation provide direct evidence of the intricate relationships among peak DC power, optimal resistive loads, and the nonlinear energy harvester design, and encourage continued study for direct analytical expressions that define such relationships.

2015 ◽  
Vol 645-646 ◽  
pp. 1223-1232
Author(s):  
Yi Ming Lei ◽  
Zhi Yu Wen ◽  
Li Chen

This paper presents two electromagnetic vibration energy harvesters based on micro-electro-mechanical (MEMS) technology. Two prototypes with different vibration structures were designed and fabricated. The energy harvester includes a permanent magnet attached on vibration structure (resonator) made by Si and a fixed wire-wound coil, with the total volume of 0.9 cm3. Two energy harvesters with different resonator are tested and compared. Experiments show that: in the same acceleration and a load resistance, the resonant frequency of prototype B is approximately 95% of prototype A; The peak-peak voltage and the maximum power of prototype B is 1.6 times and 2.7 times of prototype A respectively. The test results was analyzed simply and it indicated that the electromagnetic energy harvesting with the spring B has better performance; also proved that the potential ability of the non-linear spring could extend the frequency bandwidth and improve output voltage.


Author(s):  
Kazuhiko Adachi ◽  
Tohru Tanaka

Rotating machinery is widely used in the industrial plant. In order to ensure safety operation of the rotating machinery, vibration condition monitoring of the machinery can play a crucial role. Authors have proposed a cantilever type of vibration energy harvester for vibration condition monitoring applications of rotating machinery. Proposed energy harvester consisted of Macro-Fiber Composite (MFC). In this study, not only the DC power generation performance but also power loss in full-wave bridge rectifier of the proposed vibration energy harvester is experimentally evaluated. The maximum DC output power through 287.6(kΩ) resistor which includes instruments internal resistances obtained 109.5(μW) when subjected to vibration source input magnitude of 0.71(mm/s rms) at the resonant frequency of the harvester. The impedance matching between MFC actuators and the electrical resistive load was also effective for maximizing the DC power transfer of the vibration energy harvester. The power loss in full-wave bridge rectifier reached 13.7(μW) at the resonant frequency.


2021 ◽  
Vol 13 (5) ◽  
pp. 2865 ◽  
Author(s):  
Sungryong Bae ◽  
Pilkee Kim

In this study, optimization of the external load resistance of a piezoelectric bistable energy harvester was performed for primary harmonic (period-1T) and subharmonic (period-3T) interwell motions. The analytical expression of the optimal load resistance was derived, based on the spectral analyses of the interwell motions, and evaluated. The analytical results are in excellent agreement with the numerical ones. A parametric study shows that the optimal load resistance depended on the forcing frequency, but not the intensity of the ambient vibration. Additionally, it was found that the optimal resistance for the period-3T interwell motion tended to be approximately three times larger than that for the period-1T interwell motion, which means that the optimal resistance was directly affected by the oscillation frequency (or oscillation period) of the motion rather than the forcing frequency. For broadband energy harvesting applications, the subharmonic interwell motion is also useful, in addition to the primary harmonic interwell motion. In designing such piezoelectric bistable energy harvesters, the frequency dependency of the optimal load resistance should be considered properly depending on ambient vibrations.


Energies ◽  
2019 ◽  
Vol 12 (12) ◽  
pp. 2410 ◽  
Author(s):  
Bei Zhang ◽  
Qichang Zhang ◽  
Wei Wang ◽  
Jianxin Han ◽  
Xiaoli Tang ◽  
...  

A novel bistable electromagnetic vibration energy harvester (BEMH) is constructed and optimized in this study, based on a nonlinear system consisting mainly of a flexible membrane and a magnetic spring. A large-amplitude transverse vibration equation of the system is established with the general nonlinear geometry and magnetic force. Firstly, the mathematical model, considering the higher-order nonlinearities given by nonlinear Galerkin method, is applied to a membrane with a co-axial magnet mass and magnetic spring. Secondly, the steady vibration response of the membrane subjected to a harmonic base motion is obtained, and then the output power considering electromagnetic effect is analytically derived. On this basis, a parametric study in a broad frequency domain has been achieved for the BEMH with different radius ratios and membrane thicknesses. It is demonstrated that model predictions are both in close agreement with results from the finite element simulation and experiment data. Finally, the proposed efficient solution method is used to obtain an optimizing strategy for the design of multi-stable energy harvesters with the similar flexible structure.


2014 ◽  
Vol 953-954 ◽  
pp. 655-658 ◽  
Author(s):  
Guang Qing Shang ◽  
Hong Bing Wang ◽  
Chun Hua Sun

Energy harvesting system has become one of important areas of ​​research and develops rapidly. How to improve the performance of the piezoelectric vibration energy harvester is a key issue in engineering applications. There are many literature on piezoelectric energy harvesting. The paper places focus on summarizing these literature of mathematical modeling of piezoelectric energy harvesting, ranging from the linear to nonlinear, from early a single mechanical degree to piezoaeroelastic problems.


Author(s):  
Mustafa H. Arafa

Vibration-based energy harvesters are usually designed to exhibit natural frequencies that match those of the excitation for maximum power output. This has spurred interest into the design of devices that respond to variable frequency sources. In this work, an electromagnetic energy harvester in the form of a base excited trapezoidal plate is proposed. The plate geometry is designed to achieve two closely spaced vibration modes in order to harvest energy across a broader bandwidth. The ensuing bending and twisting vibrations are utilized in this capacity by placing a magnet on the plate tip that moves past a stationary coil. A dynamic model is presented to predict the system performance and is verified experimentally.


Author(s):  
Zahra Nili Ahmadabadi ◽  
Siamak Esmaeilzadeh Khadem

This paper presents an optimal design for a system comprising multiple nonlinear energy sinks (NESs) and piezoelectric-based vibration energy harvesters attached to a free–free beam under shock excitation. The energy harvesters are used for scavenging vibration energy dissipated by the NESs. Grounded and ungrounded configurations are examined, and the systems parameters are optimized globally to maximize the dissipated energy by the NESs. The performance of the system was optimized using a dynamic optimization approach. Compared to the system with only one NES, using multiple NESs resulted in a more effective realization of nonlinear energy pumping particularly in the ungrounded configuration. Having multiple piezoelectic elements also increased the harvested energy in the grounded configuration relative to the system with only one piezoelectric element.


Author(s):  
M. H. Ansari ◽  
M. Amin Karami

A three dimensional piezoelectric vibration energy harvester is designed to generate electricity from heartbeat vibrations. The device consists of several bimorph piezoelectric beams stacked on top of each other. These horizontal bimorph beams are connected to each other by rigid vertical beams making a fan-folded geometry. One end of the design is clamped and the other end is free. One major problem in micro-scale piezoelectric energy harvesters is their high natural frequency. The same challenge is faced in development of a compact vibration energy harvester for the low frequency heartbeat vibrations. One way to decrease the natural frequency is to increase the length of the bimorph beam. This approach is not usually practical due to size limitations. By utilizing the fan-folded geometry, the natural frequency is decreased while the size constraints are observed. The required size limit of the energy harvester is 1 cm by 1 cm by 1 cm. In this paper, the natural frequencies and mode shapes of fan-folded energy harvesters are analytically derived. The electro-mechanical coupling has been included in the model for the piezoelectric beam. The design criteria for the device are discussed.


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