The field of power harvesting has experienced significant growth over the past few years due to the ever-increasing desire to produce portable and wireless electronics with extended lifespans. Current portable and wireless devices must be designed to include electrochemical batteries as the power source. The use of batteries can be troublesome due to their limited lifespan, thus necessitating their periodic replacement. In the case of wireless sensors that are to be placed in remote locations, the sensor must be easily accessible or of a disposable nature to allow the device to function over extended periods of time. Energy scavenging devices are designed to capture the ambient energy surrounding the electronics and convert it into usable electrical energy. The concept of power harvesting works towards developing self-powered devices that do not require replaceable power supplies. A number of sources of harvestable ambient energy exist, including waste heat, vibration, electromagnetic waves, wind, flowing water, and solar energy. While each of these sources of energy can be effectively used to power remote sensors, the structural and biological communities have placed an emphasis on scavenging vibrational energy with piezoelectric materials. This article will review recent literature in the field of power harvesting and present the current state of power harvesting in its drive to create completely self-powered devices.

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A review of power harvesting using piezoelectric materials (2003–2006)

A review of vibration-based MEMS piezoelectric energy harvesters

This paper provides an analysis for the performance evaluation of a piezoelectric energy harvesting system using the synchronized switch harvesting on inductor (SSHI) electronic interface. In contrast with estimates based on a variety of approximations in the literature, an analytic expression of harvested power is derived explicitly and validated numerically for the SSHI system. It is shown that the electrical response using an ideal SSHI interface is similar to that using the standard interface in a strongly coupled electromechanical system operated at short circuit resonance. On the other hand, if the SSHI circuit is not ideal, the performance degradation is evaluated and classified according to the relative strength of coupling. It is found that the best use of the SSHI harvesting circuit is for systems in the mid-range of electromechanical coupling. The degradation in harvested power due to the non-perfect voltage inversion is not pronounced in this case, and a new finding shows that the reduction in power is much less sensitive to frequency deviations than that using the standard technique.

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An improved analysis of the SSHI interface in piezoelectric energy harvesting

On the optimal energy harvesting from a vibration source

Nowadays, harvesting energy from vibration is one of the most promising technologies. However, the majority of current researches obtain 10 µW to 100 mW power, which has only limited applications in self-powered wireless sensors and low-power electronics. In fact, the vibrations in some situations can be very large, for example, the vibrations of tall buildings, long bridges, vehicle systems, railroads, ocean waves, and even human motions. With the global concern on energy and environmental issues, energy harvesting from large-scale vibrations is more attractive and becomes a research frontier. This article is to provide a timely and comprehensive review of the state-of-the-art on the large-scale vibration energy harvesting, ranging from 1 W to 100 kW or more. Subtopics include energy assessment from large vibrations, piezoelectric materials and electromagnetic transducers, motion transmission and magnification mechanisms, power electronics, and vibration control. The relevant applications discussed in th...

Large-scale vibration energy harvesting

In this paper, a design methodology for an energy harvesting device will be investigated and results will be presented to 
validate the design. The energy harvesting device in the study is 31- unimorph piezoelectric cantilever beam which was 
used to convert small amplitude mechanical vibration from a specific machine application into an electrical energy 
source that could be used for electronic devices with low power requirements. The primary purpose of the design 
methodology is to illustrate a method to design a cantilever beam that is optimized for a particular application. The 
methodology will show how the vibration data (frequency and amplitude) from the machine was analyzed and then how 
this information was incorporated into the final design of the beam. From the given vibration data a range of frequencies 
where the energy harvesting device will generate the greatest amount of energy is determined. The device is then 
designed specifically targeting that frequency range. This approach is presented as part of a more general approach to 
designing energy harvesters for any application. Also, it will be shown how the thickness and type of materials used for 
each layer of cantilever beam were chosen, completely independent of the vibration data, without effecting the over all 
optimization process.

Energy harvesting from mechanical vibrations using piezoelectric cantilever beams

Over the past several years, there has been increasing interest in harvesting energy from ambient vibrations in the environment by converting mechanical energy into electrical energy. A popular method is to use a piezoelectric cantilever beam. In order to harvest the most energy with the device, the beam's fundamental mode must be excited. However, this is not always possible due to manufacturing of the device or fluctuations in the vibration source. By being able to change the frequencies of the beam, the device can be more effective in harvesting energy. In this paper, a model for a three layered piezoelectric cantilever beam utilizing a shunt tuning circuit will be presented. The fundamental frequency of a cantilever beam is dependent on the stiffness and mass of the beam. Either adding a tip mass to the end of the beam or increasing the dimensions of the beam can alter the mass. The stiffness of the beam is a function of the geometry, mechanical properties, and the electromechanical coupling of the piezoelectric element. In this paper we prepare the use of a piezoelectric layer with an attached shunt circuit for tuning its stiffness, and thus the beam frequency. The piezoelectric coefficients of this layer and its shunt circuit determine the amount of electromechanical coupling. By varying the shunt circuit, the beam can be tuned to a certain frequency. This paper presents a study of the effects additional harvesting and tuning layers have on the amount of tuning and generated power in the beam. These additional layers will add more piezoelectric material as well as mass to the beam and therefore there will be a balance between the amount of harvested energy and the tunable frequency range. By quantifying the effects of these parameters, it will be easier to design a harvester to be used in a particular frequency range as well as to produce a certain level of power.© 2006 ASME

Tunable Piezoelectric Cantilever Beams for Energy Harvesting

이 논문에서는 최근 다시 주목을 끌고 있는 압전소자를 이용한 에너지 획득에 대한 개념을 한 진동원에 응용하여 그 에너지의 이용가능성을 분석해 보고자 한다 에너지 획득기로는 가장 일반적으로 사용되고 있는 유니모프 압전 캔틸레버 벤더를 사용한다 먼저 압전 에너지 획득기에 대해 base excitation에서의 거동을 이론적으로 분석하고 실험실내에서 수행할 수 있는 압전 에너지 획득기를 제작하여 가진기 상에서 발생하는 전력을 측정한다 시뮬레이션과 실험결과를 통해 진동에너지로부터 획득한 전기에너지가 각종 센서는 물론 기계부품들의 진단시스템에 필요한 전원을 공급할 수 있음을 알 수 있다

David Charnegie

Papers

Energy harvesting from mechanical vibrations using piezoelectric cantilever beams

Tunable Piezoelectric Cantilever Beams for Energy Harvesting

Energy Harvesting from a Vibrating Piezoelectric Unimorph Bender