Extension modes have proven to provide sufficient ice-interface shear stresses, exceeding the adhesion strength of ice to the substrate and ensuring instantaneous ice delamination. A proposed proof of concept involves the utilization of lightweight piezoelectric actuators for deicing the leading edges of aircraft with minimal power requirements. This deicing method induces vibrations into the structure by activating its inherent extension resonant frequencies, thereby creating sufficient stress levels to fracture the ice and delaminate it from the surface. The deicing mechanism depends strongly on the chosen excitation mode, which depends on the actuator placement. Hard and soft piezoelectric actuators were used to excite extensional modes to generate shear stresses at the interface leading edge/ice great enough to delaminate the ice. Deicing was demonstrated with a power input density of 0.074 W/cm2 for a surface ratio of 0.07 hard piezoelectric actuators per cm2.
This contribution discusses a design rule for the piezoelectric actuators positioning for the excitation of extensional modes supported with experimentations.
The ability of a piezoelectric actuator in energy conversion is rapidly expanding in several applications. Some of these applications for which an ultrasound piezoelectric actuator can be used are surface cleaning, metal cutting and welding, and biomedical applications such as needleless drug delivery. A new application of piezoelectric actuators is the Avionic Deicing System. The working frequency of actuator is between 100 kHz and 150 kHz, depending on temperature and ice thickness, and output power levels at several hundreds of Watts. The power supply of piezoelectric actuators has to provide an output voltage of up to 200 VAC at the resonance frequency with low consumption. This article discusses and analyzes a low-consumption electromechanical deicing solution based on piezoelectric actuators, its operating principle, and its driving power supply development supported by experimentations on the setup representative of a part of the Nacelle.
Wind energy has been seen as a most potential renewable energy. However, in shore environments, the wind turbine usually suffers constant impact of sand and strong wind speed, which causes the surface to deteriorate: cracks may appear. To reduce the wind turbine operations and maintenance (O and M) cost, assembling a self-powered surface condition monitoring system (SCMS) becomes the most important measures. In this paper, a meso-scale piezoelectric energy harvester (PEH) was fabricated, based on a tapered cantilever beam to scavenge the rotational energy to power SCMS. The advantages are to increase its output power density and its lifetime comparing to the traditional rectangular cantilever beam. A frequency up-conversion method was adopted to accommodate PEH to working under variety of rotational speed by using two opposing magnets. With different distances between two magnets, the output voltage and the daily output energy of the PEH were investigated under 5 rpm – 30 rpm rotational speed. The maximum output voltage is 2.7 V, 9.1 V and 13.6 V when the magnets spacing is 3 mm, 2 mm and 1 mm, respectively. For the magnet spacing of 1 mm, the daily output energy of the PEH was estimated to be 5.26 J under periodic magnetic plucking at 30 rpm, much higher than the 0.2 J of SCMS’s daily energy consumption, making this harvester an excellent solution for the abovementioned needs.
Traveling wave piezoelectric transformers are a new type of multi-electrodes piezoelectric transformer allowing to obtain a multiphase system of voltages at the output. The behavior of multi-electrodes piezoelectric transformers is well characterized by an admittance matrix (Y) representing all the couplings between electrodes. The Y parameters can be determined by analytical modelling or as presented in this paper by experimental measurements. In this paper we focus on a cylinder-type multi-electrodes piezoelectric transformer on which we measure the Y parameters with a vector network analyzer. By extrapolation of Laplace expression of the admittances, we represent the Y-parameters as equivalent RLC circuits in order to have a complete circuit model available for simulation with classic electrical simulation software. The results of the simulation are compared to experimental results to validate the modelling approach.
This paper proposes a compact electromechanical modeling of multi-electrode piezoelectric transformer. This modeling can be applied to the study of standing or traveling flexural wave in piezoelectric systems and especially for ring type piezoelectric transformers. This modelling is based on the Euler-Bernoulli beam theory and from this theory and piezoelectric equations, transfer matrixes linking stresses, velocities and voltages for a beam are determined. In piezoelectric systems with no mechanical boundary in the propagation direction of the wave, for example a ring, an admittance matrix is obtained from the modeling linking all the currents and voltages. This modelling allows moreover the representation and electrical simulation of a piezoelectric element subjected to a traveling wave.
Piezoelectric transformers were adopted in recent year due to their many inherent advantages such as safety, no EMI problem, low housing profile, and high power density, etc. The characteristics of the piezoelectric transformers are well known when the load impedance is a pure resistor. However, when piezoelectric transformers are used in AC/DC or DC/DC converters, there are non-linear electronic circuits connected before and after the transformer. Consequently, the output load is variable and due to the output capacitance of the transformer the optimal working point change. This paper starts from modeling a piezoelectric transformer connected to a full wave rectifier in order to discuss the design constraints and configuration of the transformer. The optimization method adopted here use the MOPSO algorithm (Multiple Objective Particle Swarm Optimization). We start with the formulation of the objective function and constraints; then the results give different sizes of the transformer and the characteristics. In other word, this method is looking for a best size of the transformer for optimal efficiency condition that is suitable for variable load. Furthermore, the size and the efficiency are found to be a trade-off. This paper proposes the completed design procedure to find the minimum size of PT in need. The completed design procedure is discussed by a given specification. The PT derived from the proposed design procedure can guarantee both good efficiency and enough range for load variation.
Today research on supplying of low power consumption device is highly focused on piezoelectric energy harvesting from ambient vibration. The most popular structure is a cantilever beam with piezoelectric patch to convert mechanical energy into electric energy. In the past researches, the theoretical analysis and interfacing circuit design of single cantilever beam structure is highly developed. In this study, the electrical interfacing circuit of two (or more) piezoelectric generators connected to only one load is proposed and discussed. The nonlinear synchronized switching technique SSHI (Synchronized Switching Harvesting in Inductor) is examined to increase the power efficiency effectively of each piezoelectric generator. In the multiple cantilever beam or flag structure application, the structure may be composed of many piezoelectric patches and the interfacing circuit becomes more complicated and important. From the theoretical analysis and the governing equation, the equivalent circuit of two cantilever beam will be proposed and simulated with the optimized synchronous electric charge extraction (OSECE) nonlinear technique to optimize the interfacing circuit and increase the power efficiency by using the Matlab and PSIM software. The experiments will also show the good agreement with the theoretical analysis. The interfacing circuit design concept in the two cantilever beams structure can be further used in the multi-piezoelectric patches energy harvesting system such as piezoelectric flag to optimize the circuit and increase the power efficiency.
It is well known that power density of piezoelectric transformers is limited by mechanical stress. The power density of
piezoelectric transformers calculated by the stress boundary can reach 330 W/cm3. However, no piezoelectric
transformer has ever reached such a high power density in practice. The power density of the piezoelectric transformer is
limited to 33 W/cm3 typically. This fact implies that there is another physical limitation in piezoelectric transformer. In
fact, it is also known that piezoelectric material is constrained by vibration velocity. Once the vibration velocity is too
large, the piezoelectric transformer generates heat until it cracks. To explain the instability of piezoelectric transformer,
we will first model the relationship between vibration velocity and resulting heat by a physical feedback loop. It will be
shown that the vibration velocity as well as the heat generation determines the loop gain. A large vibration velocity and
heat may cause the feedback loop to enter into an unstable state. Therefore, to enhance the power capacity of
piezoelectric transformer, the heat needs to be dissipated. In this paper, we used commercial thermal pads on the surface
of the piezoelectric transformer to dissipate the heat. The mechanical current of piezoelectric transformers can move
from 0.382A/2W to 0.972A/9W at a temperature of 55°C experimentally. It implies that the power capacity possibly
increases 3 times in the piezoelectric material. Moreover, piezoelectric transformers that are well suited in applications of
high voltage/low current becomes also well suited for low voltage/high current power supplies that are widely spread.
This technique not only increases the power capacity of the piezoelectric transformer but also allows it to be used in
enlarged practical applications. In this paper, the theoretical modeling will be detailed and verified by experiments.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.