scholarly journals A Theory for Energy-Optimized Operation of Self-Adaptive Vibration Energy Harvesting Systems with Passive Frequency Adjustment

Micromachines ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 44 ◽  
Author(s):  
Mario Mösch ◽  
Gerhard Fischerauer

Self-adaptive vibration energy harvesting systems vary their resonance frequency automatically to better exploit changing environmental conditions. The energy required for the adjustment is taken from the energy storage of the harvester module. The energy gained by an adjustment step has to exceed the energy expended on it to justify the adjustment. A smart self-adaptive system takes this into account and operates in a manner that maximizes the energy output. This paper presents a theory for the optimal operation of a vibration energy harvester with a passive resonance-frequency adjustment mechanism (one that only requires energy for the adjustment steps proper, but not during the hold phases between the steps). Several vibration scenarios are considered to derive a general guideline. It is shown that there exist conditions under which a narrowing of the adjustment bandwidth improves the system characteristics. The theory is applied to a self-adaptive energy harvesting system based on electromagnetic transduction with narrowband resonators. It is demonstrated that the novel optimum mode of operation increases the energy output by a factor of 3.6.

2020 ◽  
Vol 142 (10) ◽  
Author(s):  
Shan Gao ◽  
Hongrui Ao ◽  
Hongyuan Jiang

Abstract Piezoelectric vibration energy harvesting technology has attracted significant attention for its applications in integrated circuits, microelectronic devices, and wireless sensors due to high power density, easy integration, simple configuration, and other outstanding features. Among piezoelectric vibration energy harvesting structures, the cantilevered beam is one of the simplest and most commonly used structures. In this work, a vertically staggered rectangle-through-holes (VS-RTH) cantilevered model is proposed, which focuses on the multi-directional vibration collection. To verify the output performance of the device, this paper employs basic materials and fabrication methods with mathematical modeling. The simulations are conducted through finite element methods to discuss the properties of VS-RTH energy harvester on resonant frequency and output characteristics. Besides, an energy storage circuit is adopted as a collection system. It can achieve a maximum voltage of 4.5 V which is responded to the harmonic vibrating input of 1 N force and 1 m/s2 in a single vibrating direction. Moreover, the power density is 2.596 W/cm3 with a 100 kΩ resistor. It is almost four times better than the output of unidirectional cantilever beam with similar resonant frequency and volume. According to the more functionality in the applications, VS-RTH energy harvester can be used in general vibration acquisition of machines and vehicles. Except for electricity storage, the harvester can potentially employ as a sensor to monitor the diversified physical signals for smooth operation and emergence reports. Looking forward, the VS-RTH harvester renders an effective approach toward decomposing the vibration directions in the environment for further complicating vibration applications.


Electronics ◽  
2019 ◽  
Vol 8 (12) ◽  
pp. 1446 ◽  
Author(s):  
Hyun Jun Jung ◽  
Saman Nezami ◽  
Soobum Lee

Energy harvesters generate power only when ambient energy is available, and power loss is significant when the harvester does not produce energy and its power management circuit is still turned on. This paper proposes a new high-efficiency power management circuit for intermittent vibration energy harvesting. The proposed circuit is unique in terms of autonomous power supply switch between harvester and storage device (battery), as well as self-start and control of the operation mode (between active and sleep modes). The self-start controller saves power during an inactive period and the impedance matching concept enables maximum power transfer to the storage device. The proposed circuit is prototyped and tested with an intermittent vibration energy harvester. Test results found that the daily energy consumption of the proposed circuit is smaller than that of the resistive matching circuit: 0.75 J less in sleep mode and 0.04 J less in active mode with self-start.


Author(s):  
Shan Gao ◽  
Hongrui Ao ◽  
Hongyuan Jiang

Abstract Piezoelectric vibration energy harvesting technology has attracted significant attention for its applications in integrated circuits, microelectronic devices and wireless sensors due to high power density, easy integration, simple configuration and other outstanding features. Among piezoelectric vibration energy harvesting structures, cantilevered beam is one of the simplest and most commonly used structures. In this work, a vertically staggered rectangle-through-holes (VS-RTH) cantilevered model of mesoscale piezoelectric energy harvester is proposed, which focuses on the multi-directional vibration collection and low resonant frequency. To verify the output performances of the device, this paper employs basic materials and fabrication methods with mathematical modeling. The simulations are conducted through finite element methods to discuss the properties of VS-RTH energy harvester on resonant frequency and output characteristics. Besides, an energy storage circuit with high power collection rate is adopted as collection system. This harvester is beneficial to the further application of devices working with continuous vibrations and low power requirements.


Author(s):  
Mingyi Liu ◽  
Wei-Che Tai ◽  
Lei Zuo

In rotational electromagnetic generator based vibration energy-harvesting systems, the generator rotor is an inerter. From analysis, it is found that the inerter decreases system frequency bandwidth in single-degree-of-freedom (SDOF) energy-harvesting systems. The maximum electric power output of a SDOF system is limited by mechanical damping and maximum stroke that allowed. Two-degree-of-freedom (2DOF) energy-harvesting systems was proposed in recent years and has been shown to have the potential to have better power, power/stroke ratio, and frequency bandwidth performance compared with SDOF systems. However, extra mass has to be added in most of the case. In this paper, a new design of inerter-based-2DOF energy-harvesting system was proposed by adding a spring in series with the inerter in SDOF system. No extra mass is added compared with its counterpart SDOF system. Optimal specific power at limited stroke were obtained by tuning system parameters, which includes resonance frequency ratio, spring ratio, mass ratio, and damping ratio. The contribution of each parameter to system performance was analyzed. The results show that the proposed inerter-based-2DOF system has better performance compared with the SDOF system. The inerter-based-2DOF can have larger specific power and larger power/stroke ratio over a wider frequency bandwidth. Simulation also show that improved performance not only obtained with sinusoidal excitation with constant displacement amplitude, but also with sinusoidal excitation with constant force amplitude.


Crystals ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 907
Author(s):  
Xiaodong Yan ◽  
Mupeng Zheng ◽  
Mankang Zhu ◽  
Yudong Hou

The question as to which piezoelectric composition is favorable for energy harvesting has been addressed in the past few years. However, discussion on this topic continues. In this work, an answer is provided through a feasible method which can be used in selecting piezoelectric material. The energy harvesting behavior of hard (P4 and P8) and soft (P5 and P5H) lead zirconate titanate (PZT) ceramics was investigated. The results show that the maximum piezoelectric voltage coefficient g33 and transduction coefficient d33 × g33 were obtained in P5 ceramic. Meanwhile, the power generation characteristics at low frequencies were compared by the vibration energy harvester with a cantilever beam structure. The results indicate that the energy harvester fabricated by the P5 ceramic with the maximum d33 × g33 values also demonstrated the best power generation characteristics. The results unambiguously demonstrate that the power density and energy conversion efficiency of the energy harvesting devices are dominated by the d33 × g33 value of the piezoelectric materials.


2011 ◽  
Vol 483 ◽  
pp. 626-630 ◽  
Author(s):  
Hua An Ma ◽  
Jing Quan Liu ◽  
Gang Tang ◽  
Chun Sheng Yang ◽  
Yi Gui Li ◽  
...  

As the low-power wireless sensor components and the development of micro electromechanical systems, long-term supply of components is a major obstacle of their development. One of solutions to this problem is based on the environmental energy collection of piezoelectric vibration energy harvesting. Currently, frequency band of piezoelectric vibration energy harvester is narrow and the frequency is high, which is not fit for the vibration energy acquisition in the natural environment. A piezoelectric vibration energy harvester with lower working frequency and broader band is designed and a test system to analyze the harvester is presented in this paper. The traditional mass is replaced by a permanent magnet in this paper, While other two permanent magnets are also placed on the upper and above of the piezoelectric cantilever. Experiments showed, under the 0.5g acceleration, compared with the traditional non-magnetic piezoelectric vibration energy harvesting, a piezoelectric cantilever (length 40mm, width 8mm, thickness 0.8mm) has a peak-peak voltage of 32.4V, effectively enlarges working frequency band from 67HZ-105HZ to 63HZ-108HZ.


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