Category Advances in Energy Harvesting Methods

Theoretical Model

Since the magnetic field magnitude varies along the beam length, the total induced voltage across the coil can be calculated by integrating through the solenoid, as shown in Fig. 18.5. According to Faraday’s law the open circuit voltage can be expressed by:

V d<p(t) df До fH[x, y(x) + M[x, y(x, t)]} • A • dN

Vopen = ~JT = dt

df д0М[х, y(x, t) • A • dN

dt

where M is the magnetization in the beam, A is the cross-sectional area of the beam, and dN the number of loops in the infinitesimal unit length of the solenoid dx, shown in Fig. 18.5, and

dN = N dx (18.2)

dw

Nl is the number of coil loop layers in the solenoid and dw is the copper wire diameter of the coil. The dimension of the beam in the experimental setup is

4.6 cm x 0.8 cm x 0...

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Prototype and Testing Platform

A novel vibration energy harvesting model based on the strong magnetostatic coupling between a cantilever beam and a bias magnet pair was set up and experimentally verified. The inhomogeneous bias magnetic field enables the highly permeable beam to experience complete magnetic flux reversal twice in one vibration period, which leads to maximized magnetic flux change rate in the solenoid. At the same time, the magnetic potential energy makes the cantilever vibrate in a wider potential well than in the simple harmonic case, which allows a wide working bandwidth of the harvester. The schematic design of the vibration energy harvester is shown in Fig. 18.1. The key component of this energy harvester is a high-permeability (high-p) single layer beam, with one end fixed and the other end vibrati...

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Nonlinear Vibration Energy Harvesting with High-Permeability Magnetic Materials

Xing Xing and Nian X. Sun

Abstract In this chapter, we introduce the recent demonstrations of high energy density nonlinear vibration energy harvesting with high-permeability magnetic materials, which show great promise for compact and wideband vibration energy harvesting systems. Two generations of nonlinear vibration energy harvesting technology based on high-permeability magnetic material will be discussed in this chapter. The first generation energy harvester design consists of a high-permeability magnetic cantilever beam, in a solenoid, and a hard magnet pair that provides the biasing field. The mutual interaction between the vibrating highly permeable beam and the bias magnetic field of the magnets leads to maximized flux change and therefore a large induced voltage...

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Fabrication and Characterization of MEMS Piezoelectric Energy Harvesters

For applications in microsystems, several studies have focused on developing MEMS-PVEHs using established piezoelectric film processing [25, 29-31]. In macroscale, a number of devices have been successfully developed, tested, and even available commercially (e. g., the test device used in [23] to make a cantilever with a proof mass). While fabrication of MEMS-PVEH devices is an area of active research, not many microscopic prototype devices have yet been documented. In terms of materials, lead zirconium titanate, PZT, receives the most focus and its corresponding multilayer structure is typically deposited on a Si substrate...

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Modeling of Various Electroded Piezoelectric Cantilevers for Energy Harvesting

While models for standard capacitor type electrodes—either approximated or detailed—are not hard to find in the literature, only a few modeling approaches have been attempted on IDTE configurations in PVEH devices. Jeon et al. demonstrated a MEMS-scale, {3-3} mode, piezoelectric micro-power generator with IDTEs in [21] where their calculation of output voltage and power is based only on a very simple approximation. Other prior modeling includes theoretical analysis by Mo et al. where they developed a model for unimorph piezoelectric benders with IDTEs and performed both numerical and parametric studies on energy, charge, and output voltage [27]. Their model encompasses only static considerations, and it does not consider electrode spacing...

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Device Configurations for Piezoelectric Energy Harvesting Systems

A single PVEH device typically consists of piezoelectric layers, structural layers, electrode layers, and a proof mass. The most common geometric configurations are cantilever beams or plates, because they are geometrically compatible with MEMS fabrication processes and have proven to be easy to implement and effective for harvesting energy from ambient vibrations [6]. A cantilever is a compliant structure that can not only be designed to provide low resonant frequencies, particularly by the addition of a mass on the end of the beam/plate, but also they produce high strain, and thus more power generation, in comparison with other structural configurations

[22] . There have been other efforts to enhance power performance of PVEH devices by modifying geometric configurations [4, 6]...

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Materials and Devices for MEMS Piezoelectric Energy Harvesting

Miso Kim, Seung-Hyun Kim, and Seungbum Hong

Abstract Piezoelectric vibration energy harvesters (PVEHs) for microelectrome­chanical systems (MEMS) have received considerable attention as an enabling technology for self-powered wireless sensor networks. MEMS-PVEHs are par­ticularly attractive because of the potential to deliver power required for sensor nodes and their ability to be integrated concurrently with the microfabrication of electronic circuits such as sensor nodes. This chapter consists of four subsections, starting with Sect. 17.1, where various piezoelectric materials commonly used for MEMS-scale PVEHs are reviewed. Typical device configurations of PVEH systems are introduced in Sect. 17.2, followed by analytical modeling of different configurations in Sect. 17...

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Fuel or Heat Sources: Polymer Engine Generator

The authors and colleagues have demonstrated a dielectric elastomer heat engine by making the cylinder itself out of dielectric elastomer [9]. In other words, expanding gases directly drive the expansion of the dielectric elastomer. In addition to minimizing mass and structure, this approach allows for greater efficiency of a small engine because of fewer losses from fuel leakage or friction of sliding seals, less wear, and potentially less heat loss for the same mass, since the polymer is a better thermal insulator. This work demonstrated that a polymer cylinder can indeed sustain the temperature of combustion and can provide 11% fuel-to-mechanical efficiency—a good value for a small (<20 W) engine. Figure 16.8 shows the expansion of a rolled dielectric elastomer actuator due to combust...

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