Power Of Piezoelectric Energy Harvester Research Articles

Design and evaluation of a piezoelectric-electromagnetic energy harvester with a lever structure

This paper proposes a piezoelectric-electromagnetic energy harvester with a lever structure. The prototype combines electro-magnetic energy harvester (EMH) and piezoelectric energy harvester (PEH) organically, which improves the efficiency of energy harvesting. Combining Faraday’s law of electromagnetism with a spring-mass damped system, a physical model is developed and dynamic curves are predicted at different speeds. The output voltage and power of PEH and EMH are compared theoretically and experimentally, EMH performs better at lower loads and PEH is more dominant when the load resistance is high. Experiments have demonstrated that the coupling effect of EMH and PEH is relatively weak. Consequently, it is advisable to utilise the respective advantages of these two concepts by separating them. When the number of rotor contacts is 3, and the magnet diameter and number are 20 mm and 8 respectively, the prototype output is optimal. When the external load is 2KΩ, EMH reaches a maximum power of 5.06mW, whereas PEH output reaches a maximum of 1.04mW when the external load is 10KΩ. A series of experimental tests demonstrate that the prototype is capable of simultaneously providing power to two devices.

Ultrahigh Performance Piezoelectric Energy Harvester Using Lead-Free Piezoceramics with Large Electromechanical Coupling Factor

The output power of piezoelectric energy harvester (PEH) at the resonance frequency is dependent on the electromechanical coupling factor ( k p ) of the piezoceramic, which is proportional to d 33 / ε T 33 1 / 2 , where d 33 and ε T 33 are the piezoelectric change and dielectric constants, respectively. Therefore, the piezoceramic for the PEH should have a large d 33 and a small ε T 33 . [001]-texturing can be used for developing piezoceramics for PEH because it generally increases d 33 without increasing ε T 33 . The 0.96(K0.5Na0.5)(N1-zSz)O3-0.03(Bi0.5Ag0.5)ZrO3-0.01SrZrO3 [KN(N1-zSz)-BAZ-SZ] piezoceramics were textured along the [001] orientation, and the piezoceramic ( z = 0.01 ) showed a large k p of 0.77, which is the largest k p for KNN-related piezoceramics reported in the literature. The cantilever-type PEH manufactured using the KN(N0.99S0.01)-BAZ-SZ piezoceramic exhibited a large output power density of 7.86 mW/cm3 at resonance frequency because of its large k p . To date, this is the largest power density for PEHs manufactured utilizing lead-free piezoceramics. Hence, the [001]-textured KN(N0.99S0.01)-BAZ-SZ piezoceramic is an excellent candidate for PEH, and [001]-texturing is a very efficient method for developing piezoceramics for PEH.

Physical properties of crystalline NaNbO3 thin film grown on Sr2Nb3O10 nanosheets at low temperatures for piezoelectric energy harvesters

A Sr2Nb3O10 (SN) monolayer deposited on Pt/SiO2/Si (PSS) was employed as the template for the growth of crystalline NaNbO3 (NNO) thin films at low temperatures. The [001]-oriented crystalline NNO film was effectively grown on SN/PSS at 250 °C. This NNO film showed a small εr of 115, along with good insulating properties with a low leakage-current density (4.5 × 10–6 A/cm2 at 0.3 MV/cm). This NNO film displayed a large d33 of 123 pC/N, which is the largest d33 value for NNO films to date. Moreover, it shows a very large d33 × g33 (14.8 × 10–12 m2/N), which is the figure of merit for the power of piezoelectric energy harvesters (PEHs). The NNO film grown on SN/Ni at 250 °C for the fabrication of PEH also demonstrated dielectric and piezoelectric characteristics. The NNO PEH exhibited a high power density (2.1 μW/mm3), indicating that the [001]-oriented NNO film grown on the SN seed layer is a good candidate for PEH. Moreover, this NNO film can be deposited on a polymer substrate and utilized as a future flexible device owing to its very low growth temperature and good physical properties.

Modeling and analysis of energy harvester based on galloping considering the non-homogeneous beam

ABSTRACT This paper proposes a piezoelectric energy harvester based on non-homogeneous beam, which is employed to capture wind energy by galloping. A distributed parameter model of piezoelectric energy harvester with the nonuniformity of cantilever beam is developed. The quasi steady state approximation is used to simulate the fluid force. The model is verified by the experimental results reported previously. The influences of load resistance, the position of piezoelectric patch, and the size of beam on the output power are studied. Finally, a set of optimization parameters are generated to study the performance of the energy harvester. The results show that compared with rectangular beam, the output power of piezoelectric energy harvester with non-homogeneous beam can be increased by 32%.

Piezoelectric energy harvesting from roadway deformation under various traffic flow conditions

Many laboratory tests and in situ measurements have been conducted to study piezoelectric energy harvesting from roadway deformation. However, the performance of piezoelectric energy harvesters under real traffic flow conditions is still unknown. In this study, an electromechanical model of piezoelectric energy harvesters with detailed parameters (including the geometric parameters, material parameters, and circuits) is established, and the influences of traffic flow conditions (i.e. traffic speed and traffic density) on the output power of piezoelectric energy harvesters are analyzed by employing a scaling law method and traffic flow theory. The results indicate that remarkable differences exist in the load patterns and the frequencies between the laboratory tests (or in situ measurements) and real traffic flow conditions. Because of these differences, the results (especially the output electric power and optimization design methods) of previous studies may be inapplicable for piezoelectric energy harvesters embedded in roadways. Considering the distinguishing features of the traffic load pattern, the optimization criteria to determine the geometric parameters and the intrinsic system parameter of piezoelectric energy harvesters are obtained, and the corresponding optimal output power densities of the piezoelectric energy harvesters are also quantitatively calibrated. These theoretical results may serve as guidelines for optimizing the design of piezoelectric energy harvesters embedded in roadways under different traffic flow conditions.

Design and Analysis of a Magnetically Coupled Multi-Frequency Hybrid Energy Harvester.

The approach to improve the output power of piezoelectric energy harvester is one of the current research hotspots. In the case where some sources have two or more discrete vibration frequencies, this paper proposed three types of magnetically coupled multi-frequency hybrid energy harvesters (MHEHs) to capture vibration energy composed of two discrete frequencies. Electromechanical coupling models were established to analyze the magnetic forces, and to evaluate the power generation characteristics, which were verified by the experimental test. The optimal structure was selected through the comparison. With 2 m/s2 excitation acceleration, the optimal peak output power was 2.96 mW at 23.6 Hz and 4.76 mW at 32.8 Hz, respectively. The superiority of hybrid energy harvesting mechanism was demonstrated. The influences of initial center-to-center distances between two magnets and length of cantilever beam on output power were also studied. At last, the frequency sweep test was conducted. Both theoretical and experimental analyses indicated that the proposed MHEH produced more electric power over a larger operating bandwidth.

A Passive Design Scheme to Increase the Rectified Power of Piezoelectric Energy Harvesters

Piezoelectric vibration energy harvesting is becoming a promising solution to power wireless sensors and portable electronics. While miniaturizing energy harvesting systems, rectified power efficiencies from miniaturized piezoelectric transducers (PTs) are usually decreased due to insufficient voltage levels generated by the PTs. In this paper, a monolithic PT is split into several regions connected in series. The raw electrical output power is kept constant for different connection configurations, as theoretically predicted. However, the rectified power following a full-bridge rectifier (FBR), or a synchronized switch harvesting on an inductor (SSHI) rectifier, is significantly increased due to the higher voltage/current ratio of series connections. This is an entirely passive design scheme without introducing any additional quiescent power consumption, and it is compatible with most of the state-of-the-art interface circuits. Detailed theoretical derivations are provided to support the theory, and the results are experimentally evaluated using a custom microelectromechanical system PT and a complementary metal–oxide–semiconductor rectification circuit. The results show that, while a PT is split into eight regions connected in series, the performance while using an FBR and an SSHI circuit is increased by 2.3 $\times$ and 5.8 $\times$ , respectively, providing an entirely passive approach to improving energy conversion efficiency.

The effects of width reduction on the damping of a cantilever beam and its application in increasing the harvesting power of piezoelectric energy harvester

Previous work shows that when a cantilever piezoelectric energy harvester with a given width is split into several pieces and then electrically connected in parallel, the output power increases substantially compared with when it acts in a single piece with a similar total width. It was hypothesized that this increase is due to the reduction in the damping of the width-reduced beam. As a result, the beam with the smaller width vibrates with higher amplitudes and therefore has higher energy harvesting capability. In this paper, this hypothesis is examined by measuring the damping of the cantilever beam as its width is reduced. It is shown that as the width decreases, the damping is reduced, which contributes to the increase in the harvested power. It is then shown that the harvested energy from an array of cantilever piezobeams with a certain total width is higher than that from a single-piece harvester of similar width.

Increasing the power of piezoelectric energy harvesters by magnetic stiffening

A piezoelectric cantilever beam with a tip mass at its free end is a common energy harvester configuration. This article introduces a new principle of designing such a harvester that increases the generated power without changing the resonance frequency of the harvester: the attraction force between two permanent magnets is used to add stiffness to the system. This magnetic stiffening counters the effect of the tip mass on the efficient operation frequency. Five set-ups incorporating piezoelectric bimorph cantilevers of the same type in different mechanical configurations are compared theoretically and experimentally to investigate the feasibility of this principle: theoretical and experimental results show that magnetically stiffened harvesters have important advantages over conventional set-ups with and without tip mass. They generate more power while only slightly increasing the deflection in the piezoelectric harvester and they can be tuned across a wide range of excitation frequencies.

Fabrication and analytical modeling of transverse mode piezoelectric energy harvesters

ABSTRACTA transverse (d33) mode piezoelectric cantilever was fabricated for energy harvesting. Various dimensions of interdigital electrodes (IDE) were deposited on a piezoelectric layer to examine the effects of electrode design on the performance of energy harvesters. Modeling was performed to calculate the output power of the devices. The estimation was based on Roundy’s analytical modeling derived for a d31 mode piezoelectric energy harvester (PEH). In order to apply the Roundy’s model to d33 mode PEH, the IDE configuration was converted to the area of top and bottom electrodes (TBE). The power conversion in d33 mode PEH was commonly estimated by the product of piezoelectric layer’s thickness and finger electrode’s length. In addition, the spacing between fingers was regarded as gap between top and bottom electrodes. However, the output power in a transverse mode PEH increases continuously with the increase of finger spacing, which does not correspond to experimental results. In this research, the dimension of IDE was converted to that of TBE using conformal mapping, and variation of power of PEH was remodeled. The modified model suggests that the maximum power in a transverse mode PEH is obtained when the finger spacing is identical with effective finger spacing. The output power then decreases when finger spacing is larger than effective finger spacing. The decrease of efficiency may result from insufficient degree of poling and increased charged defect with increasing finger spacing.