Anthony Marin

Multi-mechanism vibration harvester combining inductive and piezoelectric mechanisms

With increasing demand for wireless sensor nodes in automobile, aircraft and rail applications, the need for energy harvesters has been growing. In these applications, energy harvesters provide a more robust and inexpensive power solution than batteries. In order to enhance the power density of existing energy harvesters, a variety of multimodal energy harvesting techniques have been proposed. Multi-modal energy harvesters can be categorized as: (i) Multi-Source Energy Harvester (MSEH), (ii) Multi-Mechanism Energy Harvester (MMEH), and (iii) Single Source Multi-Mode Energy Harvester (S2M2EH). In this study, we focus on developing MMEH which combines the inductive and piezoelectric mechanisms. The multi-mechanism harvester was modeled using FEM techniques and theoretically analyzed to optimize the performance and reduce the overall shape and size similar to that of AA battery. The theoretical model combining analytical and FEM modeling techniques provides the system dynamics and output power for specific generator and cymbal geometry at various source conditions. In the proposed design, a cylindrical tube contains a magnetic levitation cavity where a center magnet oscillates through a copper coil. Piezoelectric cymbal transducers were mounted on the top and bottom sections of the cylindrical shell. In response to the external vibrations, electrical energy was harvested from the relative motion between magnet and coil through Faradays effect and from the piezoelectric material through the direct piezoelectric effect. Experimental results validate the predictions from theoretical model and show the promise of multimodal harvester for powering wireless sensor nodes in automobile, aircraft, and rail applications.

Enhanced Vibration Energy Harvesting Through Multilayer Textured Pb(Mg1/3Nb2/3)O3–PbZrO3–PbTiO3 Piezoelectric Ceramics

Abstract High-performance low-cost multilayer textured Pb(Mg1/3Nb2/3)O3–PbZrO3–PbTiO3 (PMN–PZT) piezoelectric ceramic benders were fabricated by combining templated grain growth (TGG) and low-temperature co-firing ceramics (LTCC) process. The d×g values of textured samples were 700–800% higher than that of the random counterpart, which results in 500–600% increase in the output power from vibration energy harvesting. The output power and power density of tri-layer textured sample at the acceleration of 0.43 g were measured to be 903 µW and 15.5 mW/cm3, respectively. The results demonstrate that the multilayer structure results in an increase in output current and a decrease in the matching resistive load.

Multi-Mechanism Non-Linear Vibration Harvester Combining Inductive and Magnetostrictive Mechanisms

In this study, we focus on developing a multi-mechanism energy harvester (MMEH) which combines magnetostrictive and inductive mechanisms with overall shape and size similar to AA battery. The multi-mechanism harvester was theoretically modeled, fabricated and experimentally characterized. The theoretical model combining analytical and FEM modeling techniques provides the system dynamics and output power for specific generator and magnetostrictive geometry at various source conditions. The prototype consisted of a cylindrical tube containing a magnetic levitation cavity where a center magnet oscillated through a copper coil. Magnetostrictive rods were mounted on the bottom and top cap of the cylindrical tube. In response to external vibrations, electrical energy was harvested from the relative motion between magnet and coil through Faradays effect and from the magnetostrictive material through the Villari effect. The experimental results were compared to theoretical predictions for both mechanisms which showed reasonable agreement. The difference between model predictions and experiments are discussed in detail. The inductive mechanism generated 5.3 mW, 2.57 mW, 0.27 mW at 0.9 G, 0.7 G and 0.4 G respectively.

Improved pen harvester for powering a pulse rate sensor

With the continued advancement in electronics the power requirement for micro-sensors has been decreasing opening the possibility for incorporating on-board energy harvesting devices to create self-powered sensors. The requirement for the energy harvesters are small size, light weight and the possibility of a low-budget mass production. In this study, we focus on developing an energy harvester for powering a pulse rate sensor. We propose to integrate an inductive energy harvester within a commonly available pen to harvest vibration energy from normal human motions like jogging and jumping. An existing prototype was reviewed which consists of a magnet wedged between two mechanical springs housed within a cylindrical shell. A single copper coil surrounds the cylindrical shell which harvests energy through Faradays effect during magnet oscillation. This study reports a design change to the previous prototype providing a significant reduction in the device foot print without causing major losses in power generation. By breaking the single coil in the previous prototype into three separate coils an increase in power density was achieved. Several pulse rate sensors were evaluated to determine a target power requirement of 0.3 mW. To evaluate the prototype as a potential solution, the harvester was excited at various frequencies and accelerations typically produced through jogging and jumping motion. The improved prototype generated 0.043 mW at 0.56 grms and 3 Hz; and 0.13 mW at 1.14 grms at 5 Hz. The design change allowed reduction in total volume from 8.59 cm3 to 1.31 cm3 without significant losses in power generation.

Combinatory piezoelectric and inductive vibration energy harvesters

This paper provides an overview of vibration energy harvesting techniques using combinatory piezoelectric and inductive vibration energy harvesters. We provide detailed analysis of both mechanisms by comparing and contrasting the design, operating principle, and performance of each harvester. After introducing the two types of mechanisms, we discuss the methods to increase the power density through optimization of electromechanical coupling factor. The electromechanical coupling factor directly couples the input mechanical energy to the output electrical energy. The paper concludes with review of state-of-the-art for combinatory vibration energy harvesters citing their volume and bandwidth.

Micro Wind Turbine for Powering Wireless Sensor Nodes

Abstract The goal of this study was to design a micro wind turbine having dimensions on the order of 1–10 cm3 for powering wireless sensor nodes. Using the parametric study based upon a computational model, the coupling factor between the blade and generator section was significantly enhanced. Building upon the formulation for the coupling factor, we derived efficiency metric for the rotational generators. A prototype was designed based upon the analytical study conducted through the combination of blade element momentum theory and ANSYS magnetics to match the performance of the generator to that of the blades. The blade diameter and depth was 72 mm and 9 mm, respectively. The generator diameter was 26 mm with total volume of 18.1 cm3. It was found that the micro wind turbine generated DC output power of 12.39 mW, 49.03 mW and 102.61 mW at 3.7 m/s, 6 m/s and 8 m/s wind speeds, respectively. The power density was computed to be 0.304, 1.204, and 2.52 mW/cm2, respectively, which are higher than all the other results reported in the literature.

High Efficiency Vibration Energy Harvesting Through Combined Isolator and Absorber Approach

Abstract Relative motion is required for vibration energy harvesting, such as magnet moving past the coil in inductive approach and tip-mass motion in piezoelectric approach. Typically, relative motion is created by amplifying the source displacement and storage of mechanical energy in an auxiliary vibrating mass. In this study, we propose a novel technique to create the relative motion without amplification of the original source displacement. The technique relies on cancelling the vibration at one location and transferring the source vibration directly to another location through combination of a vibration isolator with a vibration absorber. In this multi-degree of freedom configuration, the power is harvested from the displacement of the vibrating source rather than the displacement of an auxiliary mass. This configuration eliminates the need to capture relative motion with respect to an externally fixed component. A prototype was designed and fabricated based on this concept which was found to harvest 45 mW at 0.9 G base acceleration and weighed 462 g. Through analytical modeling it was determined that the prototype could generate 87 mW @ 1 G base acceleration, while weighing only 243 g. Also, an optimal balance between the bandwidth and the maximum power harvested was identified through parametric analysis.

Efficient Direct-Drive Small-Scale Low-Speed Wind Turbine

Abstract There is growing need for the green, reliable, and cost-effective power solution for the expanding wireless microelectronic devices. In many scenarios, these needs can be met through a small-scale wind energy portable turbine (SWEPT) that operates near ground level where wind speed is of the order of few meters per second. SWEPT is a three-bladed, 40 cm rotor diameter, direct-drive, horizontal-axis wind turbine that has very low cut-in wind speed of 1.7 m/s. It operates in a wide range of wind speeds between 1.7 m/s and 10 m/s and produces rated power output of 1 W at wind speed of 4.0 m/s. The wind turbine is capable of producing electrical power up to 9.8 W at wind speed of 10 m/s. The maximum efficiency of SWEPT was found to be around 21% which makes it one of the most efficient wind turbines reported at the small scale and low wind speed. These advancements open many new opportunities for embedding and utilizing wireless and portable devices.