• Journal of the Korean Society for Precision Engineering
• /
• v.31 no.10
• /
• pp.935-945
• /
• 2014

This paper presents a new road generative system that employs a pad of preventive overspeed or tollgate. The system consists of pad, shaft, torsional damper, oneway-clutch, gear system, and electricity generator components. When the car driven through the road generation system, it occurred to surplus energy in the DC power. In order to maximize the power of electricity energy harvester, the simulation software is developed. It is used to determine parametric dimension for optimal design with the theoretically calculated results from the simulation software. The transient responses at the conditions of low and high vehicle speed are compared with the calculated results as torque, impact force, power, out energy etc. Consequently, before design a road generation system, the analysis of simulation results shows that the proposed concept and system has efficiency and confidence.

• ETRI Journal
• /
• v.44 no.5
• /
• pp.759-768
• /
• 2022

A novel energy harvesting technique that uses conducted electromagnetic interference as an energy source is presented. Conducted EMI generated from fluorescent light using a switched-mode power supply was measured and modeled as an equivalent voltage source. Two types of rectifier circuits-a bridge rectifier and a voltage doubler-were used as the harvesting devices for conducted EMI source. The matching networks were designed based on the equivalent model, and the harvested power was improved. The implemented energy harvester produces a regulated power over 68.9 mW and current over 15.1 mA while a regulated voltage can be selected between 3.3 V and 5 V. The proposed system shows the highest harvesting power indoor environment and can provide enough power for the Internet of Things devices.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.25 no.10
• /
• pp.766-772
• /
• 2012

Spring supported piezoelectric cantilever structures (SPCS) were fabricated for vibration-based energy harvester application. We selected four elastic springs (A, B, C, and D type) as cantilever's supporter, each elastic spring has a different spring constant (S). The C type of SPCS ($S_C$: 4,649 N/m) showed a extremely low resonance frequency of 81 Hz along with the highest power output of 38.5 mW while the A type of SPCS ($S_A$: 40,629 N/m) didn't show a resonance frequency while. Therefore, it is considered that the lower spring constant lead to a lower resonance frequency of the SPCS. In addition, a tip mass (18 g) at one end of the SPCS could further reduce the resonance frequency without heavy degradation of power output.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.25 no.6
• /
• pp.406-413
• /
• 2015

The piezoelectric coupling in piezoelectric vibration energy harvesters with load resistance induces electrical damping as well as increase in the system stiffness. Starting from analytically deriving the explicit relations through governing equations in the frequency domain, this work identifies the characteristics of the electrically induced damping mechanism and shows that the electrically induced damping serves as a structural hysteretic damping on condition that a piezoelectric vibration energy harvester is excited at its short-circuit resonant frequency and its load resistor is optimally impedance- matched at the same time. Finally, it is analytically verified that the equivalence of a mechanical and an electrically induced damping ratio is required for the maximum power generation at a load resistor, which was claimed in some literature.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2014.10a
• /
• pp.539-543
• /
• 2014

This work investigated the electromechanical performance of a cantilevered vibration energy harvester incorporating the single crystal PMN-PZT, manufactured with the most recent technology of solid-state single crystal growth. Single crystal PMN-PZTs with two different crystallographic axes such as [011] and [001] were considered. For the [011] orientation, because material properties such as the stiffness, piezoelectric strain coefficients are not the same in the directions normal to the crystallographic axis, the effects of the transversely anisotropy on the magnitude and frequency bandwidth of output power were also analyzed.

• Advances in Computational Design
• /
• v.1 no.2
• /
• pp.155-173
• /
• 2016

This paper presents a method of design for the energy harvesting of a piezoelectric cantilever beam. Vibration modes have strain nodes where the strain distribution changes in the direction of the beam length. Covering the strain nodes of the vibration modes with continuous electrodes effects a cancellation of the voltages outputs. The use of segmented electrodes avoids cancellations of the voltage for multi-mode vibration. The resistive load affects the voltage and generated power. The optimum resistive load is considered for segmented and continuous electrodes, and then the power output is verified. One of the effective parameters on energy harvesting performance is the existence of concentrated mass. This topic is studied in this paper. Resonance and off-resonance cases are considered for the harvester. In this paper, both theoretical and experimental methods are used for satisfactory results.

• Ceramist
• /
• v.23 no.1
• /
• pp.54-88
• /
• 2020

Global effort has resulted in tremendous progress with energy harvesters that extract mechanical energy from ambient sources, convert it to electrical energy, and use it for systems such as wrist watches, mobile electronic devices, wireless sensor nodes, health monitoring, and biosensors. However, harvesting a single energy source only still pauses a great challenge in driving sustainable and maintenance-free monitoring and sensing devices. Over the last few years, research on high-performance mechanical energy harvesters at the micro and nanoscale has been directed toward the development of hybrid devices that either aim to harvest mechanical energy in addition to other types of energies simultaneously or to exploit multiple mechanisms to more effectively harvest mechanical energy. Herein, we appraise the rational designs for multiple energy harvesting, specifically state-of-the-art hybrid mechanical energy harvesters that employ multiple piezoelectric and triboelectric mechanisms to efficiently harvest mechanical energy. We identify the critical material parameters and device design criteria that lead to high-performance hybrid mechanical energy harvesters. Finally, we address the future perspectives and remaining challenges in the field.

• Ceramist
• /
• v.22 no.2
• /
• pp.122-132
• /
• 2019

Wearable electronic devices with batteries must be lightweight, flexible and highly durable. Most importantly, the battery should be able to self-generate to operate the devices without having to be too frequently charged externally. An eco-friendly energy harvesting technology from various sources, such as solar energy, electromagnetic energy and wind energy, has been developed for a self-charging flexible battery. Although the energy harvesting from such sources are often unstable according to the surrounding environment, the energy harvesting from body movements and vibrations has been less affected by the surrounding environment. In this regard, flexible piezoelectric modules are the most attractive solution for this issue, because they convert mechanical energy to electrical energy and harvest energy from the human body motions. Among the various flexible piezoelectric modules, piezoelectric nanofibers have advantages when used as an energy harvester in wearable devices, due to their simple manufacturing process with good applicability to polymers and ceramics. This review focused on diverse flexible piezoelectric nanofibers and discusses their applications as various energy harvesting systems.

• Proceedings of the KIPE Conference
• /
• 2016.07a
• /
• pp.463-464
• /
• 2016

본 논문은 압전소자 발전기를 이용하여 하베스팅 에너지 발전량을 증대시키기 위한 에너지 하베스팅 방법을 제안하였다. 기존의 풀브리지 정류기만을 이용한 standard DC 방법에 압전소자와 병렬로 공진을 위한 인덕터와 MOSFET를 연결하여 parallel SSHI 회로를 구성하였으며, 또한 변위센서와 비교기를 통해 스위치 시점을 결정한다. 시뮬레이션 분석을 위해 압전발전기를 등가회로로 모델링하였으며, standard DC방법과 parallel SSHI 방법의 성능을 비교하여 parallel SSHI 방법이 standard DC 방법보다 약 13%의 전력이 증대된 것을 확인 하였다.

• Proceedings of the KIEE Conference
• /
• 2015.07a
• /
• pp.1221-1222
• /
• 2015

본 연구에서는 촉각 센서와 에너지 수확소자가 한 소자에 융합되어있는 구조를 제안한다. 이 소자는 압전 스트랩과 유연한 튜브, 폴리머 필름으로 구성되어있으며, 유연하며 잘 늘어나는 직물구조를 갖는다. 완성된 소자에 수평방향의 인장 및 수축 힘이 가해지면 전압이 발생하여 에너지 수확소자로 동작하며, 수직방향의 힘이 가해지면 정전용량이 변화하여 촉각센서로 동작한다. 제작한 소자가 에너지 수확소자로 동작할 때 최대 36.6 V의 출력 전압이 측정되었으며, 소자를 누르는 수직힘이 증가할수록 정전용량이 커지는 것을 확인하였다.