Attaining the high-energy orbit of nonlinear energy harvesters by load perturbation

2019 ◽  
Vol 192 ◽  
pp. 30-36 ◽  
Author(s):  
Jiahua Wang ◽  
Wei-Hsin Liao
2015 ◽  
Vol 106 (9) ◽  
pp. 093901 ◽  
Author(s):  
Shengxi Zhou ◽  
Junyi Cao ◽  
Daniel J. Inman ◽  
Shengsheng Liu ◽  
Wei Wang ◽  
...  

AIP Advances ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 085315
Author(s):  
P. V. Malaji ◽  
M. I. Friswell ◽  
S. Adhikari ◽  
G. Litak

Author(s):  
Jiahua Wang ◽  
Bao Zhao ◽  
Junrui Liang ◽  
Wei-Hsin Liao

Abstract Nonlinear energy harvesters have been widely studied in the last decade. Their broad bandwidth and relatively high power output contribute to energy harvesting applications. However, the coexisting multiple orbits brought by the nonlinearity weaken the performance of nonlinear energy harvesters. This paper proposes to achieve orbit jumps of monostable energy harvesters by a bidirectional energy conversion circuit. Changing the switch control sequence in the bidirectional energy conversion circuit facilitates it with both the energy harvesting and vibration exciting functions. Thus, a nonlinear energy harvester in connection with the circuit can harness ambient energy as well as excite itself, through energy harvesting and vibration exciting modes separately. Based on the concept of vibration exciting, the energy saved in the storage is used to stimulate the piezoelectric transducer for a larger vibration amplitude, which enables orbit jumps. The working mechanism of the circuit is introduced. Experimental setup of a monostable energy harvester has been developed to validate the proposed method. The monostable system can be stimulated to high-energy orbit from a small vibration amplitude by the vibration exciting mode of the circuit. It is also revealed that the method can achieve orbit jumps in a wide frequency range within the hysteresis area. Evaluations on energy consumption and energy gain show that the sacrificed energy can be quickly recovered. A novel approach for orbit jumps of monostable energy harvesters is performed so as to open new opportunities for monostable energy harvesters.


Author(s):  
Jiahua Wang ◽  
Wei-Hsin Liao ◽  
Junyi Cao

Energy harvesting has been regarded as a potential solution for power problems in wireless sensor network applications over batteries. Nonlinear configurations, as one of the most promising methods for broadening bandwidth, still make the system suffer from the coexistence of high-energy orbit and low-energy orbit, which significantly reduces output power. This paper proposes the electromagnetic kick method to enhance the output power of a monostable energy harvester through orbit jumps. The so-called electromagnetic kick is introduced by a solenoid consisting of a coil from the electromagnetic energy harvester and a three-volt button battery. The modeling and analysis demonstrate the excitation capability of the electromagnetic kick for orbit jumps. Inspired by a swing, two strategies are derived as the single kick and cycled kick. Based on an experimental setup, parameters for two strategies are first determined. The single kick and the cycled kick are then respectively employed to realize orbit jumps for the energy harvester under varying excitation and loading conditions. For each scenario, twenty trials are repeated to investigate the probability and capability. The system power output can be boosted from null to over 360 µW after orbit jumps, and the consumed energy can be resumed within 20 s. In addition, to evaluate different orbit jumping approaches in the literature, a figure of merit is developed, and the comprehensive advantages of the electromagnetic kick approach are demonstrated. The proposed effortless and efficient orbit jumping strategy expands the possibilities of realistic applications of nonlinear energy harvesters. The defined figure of merit not only makes it possible to compare different orbit jumping methods but also opens the door to new strategy development.


Author(s):  
Sumin Seong ◽  
Christopher Mullen ◽  
Soobum Lee

This paper presents reliability-based design optimization (RBDO) and experimental validation of the purely mechanical nonlinear vibration energy harvester we recently proposed. A bi-stable characteristic was embodied with a pre-stressed curved cantilever substrate on which piezoelectric patches were laminated. The curved cantilever can be simply manufactured by clamping multiple beams with different lengths or by connecting two ends of the cantilever using a coil spring. When vibrating, the inertia of the tip mass activates the curved cantilever to cause snap-through buckling and makes the nature of vibration switch between two equilibrium positions. The reliability-based design optimization study for maximization of power density and broadband energy harvesting performance is performed. The benefit of the proposed design in terms of excellent reliability, design compactness, and ease of implementation is discussed. The prototype is fabricated based on the optimal design result and energy harvesting performance between the linear and nonlinear energy harvesters is compared. The excellent broadband characteristic of the purely mechanical harvester will be validated.


Author(s):  
Hanxiao Wu ◽  
Zhi Tao ◽  
Haiwang Li ◽  
Tiantong Xu ◽  
Wenbin Wang ◽  
...  

Abstract In this paper, we present a systematic theoretical and numerical study of the output performance of nonlinear energy harvesters. The general analytical expression of output power for systems with different combinations of nonlinear stiffness and nonlinear damping, as well as symmetrical and asymmetrical systems, have been derived based on harmonic balance method, observing compliance with numerical results. We theoretically prove that there is a limit power for all nonlinear systems which is determined exclusively by the vibrator mass, excitation acceleration, and mechanical damping. The results also indicate that for symmetrical stiffness systems, the asymmetrical damping components have no effect on the output performance. Additionally, we derived semi-analytical solutions of the matching loads and numerically investigated the influence of nonlinear coefficients on the output power with matched load. When the load matches device parameters and is much larger than the internal resistance, the equivalent time-average damping is equal to the mechanical damping. Although the matching load and output power vary with the nonlinear coefficients, the normalized power and matching resistance ratio follow a power function, named matching power line, which is independent of the structural parameters. With the improvement of the equivalent time-average short-circuit damping in the vibration range, the normalized power moves to the right end of the matching power line, and the output power approach to the limit power. These conclusions provide general characteristics of nonlinear energy harvesters, which can be used to guide the design and optimization of energy harvesters.


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