Papers by Keyword: Piezoelectric Transformer

Abstract: This paper presents the results of experimental work on thin piezoelectric polyvinylidene fluoride (PVDF) film, used as active layer in piezoelectric transformer. PVDF film was deposited by spray deposition technique on flexible polyethylene terephthalate (PET) substrate and its thickness was measured to be 2 μm. Aluminum (Al) bottom and top contacts were deposited by vacuum thermal evaporation. The transfer function of the transformer was measured at different frequencies in the range 50 Hz – 4 MHz. It was observed that at input frequency of 1 MHz, the transfer function started to decrease, which supposed low-frequency AC/AC transformer. Dielectric losses, which characterize piezoelectric devices’ quality, were less that 0.09 in the whole frequency range. This is proof for the efficient energy conversion and stable operation of the microstructure. The work shows that the PVDF transformer performance is comparable to the existing piezoceramic based transformers, which however suffer of high dielectric losses, signal distortions and relatively low boundary frequency.

Abstract: PZT ceramic system with presence of La contents, have been proposed and prepared using sol gel sintering method for practical application of photostriction, which is the superposition of photovoltaic and piezoelectric effects. Such a ceramics produced by conventional mixing oxide method does not exhibit photostrictive properties due to the defects and inhomogeneous distribution of grains and pores. In this study, an investigated lanthanium(III) doped PZT ceramics were obtained by sol-gel technique from the organometallic precursors. It was found that fabricated material were effective in the enhancement of photovoltaic and photostrictive properties. Consequently, lanthanium influence deviation of piezoelectric parameters were studied as a function UV light illumination. For the determination lighting dependancy of the transformation parameters the resonant and antiresonant method was implemented. The improved Piezoelectric Transformer structure successfully changed gain characteristics proportionally to light intensity. The authors invention of a light driven output gain adjustment in Piezoelectric Transformers (PT) yields a novel “smart” multifunctional wireless device. This new created application area can be utilized in self-adopting shutters in photo cameras due to improved sensitivity to surrounding illumination conditions.

Abstract: For the growing interest in developing of more attractive multiferroic and magnetoelectric ceramics an alternative is a double-doped Pb(Zr1-_xTi_x)O₃- material with trivalent lanthanum and iron ions. Such material has a structure based on ABO₃ perovskite and properties depending on the chemical and structural composition. In the present work the results of the preparation and characterization of Fe³⁺- modified 9/65/35 PLZT ceramics have been reported. Two samples of Pb_0,91(La_1-zFe_z)_0,09(Zr_0,65Ti_0,35)_0,9775O₃ ceramics, for different Fe ions concentration (z = 0,0 and 0,5 at.%), were prepared from the MOM derived powders and sintered by the hot uniaxial pressing methods. To analyze the obtained ceramics properties the XRD, SEM and also application oriented dielectric and magnetic measurements were performed. The Fe³⁺ substitution at the La-site of PLZT has shown many interesting and unusual dielectric, piezoelectric and magnetic properties. The obtained material was proposed to implement into Piezoelectric Transformer structure to change gain characteristics proportionally to magnetic field intensity.

Abstract: Safety, environmental protection and energy saving are three main measures of development level of modern automotive technology, where safety is in the first place. With people's living standards improvement, more and more users will choose the higher configuration, safer cars. These promote a high-performance automobile airbag system development. Ignition system is a key component of the airbag. Because of reliability, accuracy and other limitations, the existing airbag ignition system doesn’t work well. In this paper, a high-voltage piezoelectric converter used in car airbag ignition systems is discussed. It is the combination of safety and environmental protection, and improves the reliability and accuracy. The solution includes conversion circuit model of piezoelectric ignition system, frequency characteristics of piezoelectric transducer, quantum-based control technology for optimal efficiency of transformation and a starting control design of automobile airbag ignition system on piezoelectric transformer. The experiment results verify the correctness of design.

Abstract: Piezoelectric transformers are electronic devices made from piezoelectric materials. The piezoelectric transformers as the name implied are used for changing voltage signals from one level to another. Electrical energy carried with signals is transferred by means of mechanical vibration. Characterizing in both electrical and mechanical properties leads to extensively use and efficiency enhancement of piezoelectric transformers in various applications. In this paper, study and analysis of electrical and mechanical properties in forms of potential and displacement distribution throughout the volume, respectively, are discussed and especially focused on around its natural frequency. This paper proposes a set of quasi-static mathematical model of electro-mechanical coupling for piezoelectric transformer by using a set of partial differential equations. Computer-based simulation utilizing the three-dimensional finite element method (3-D FEM) is exploited as a tool for calculation in two purposes. The first use is developed the 3-D FEM for identifying its natural frequencies while the second use is for visualizing potentials and displacements distribution within the piezoelectric transformer. The computer simulation based on the use of the FEM has been developed in MATLAB programming environment. In addition, which satisfactory results of natural frequencies are compared with those obtained from the experiment and the accuracy of 3-D FEM model is confirmed.

Abstract: The multi-point initiation control technology of electronic security systems uses high-performance and high-pressure transformer, which gains efficient multiple high-pressure slapper ignition energy. Because of its small size, light weight, good high frequency performance characteristics of electronic security systems for the high-voltage transformation circuit, piezoelectric transformer provides a new solution. Firstly, the structure and working principle of electronic security systems based on piezoelectric pressure converter is discussed in this paper. By analyzing the high-voltage converter output circuit of the equivalent load of converter, the frequency characteristics of the charging process for the piezoelectric-driven frequency high-voltage converter is designed in theory. To improve the efficiency of its high-voltage charge, control circuits such as quantum-based control mode design is presented. At last, high-voltage converter of piezoelectric multi-point initiation of electronic security systems technology is given here.

Abstract: The PZT-PMN ceramics system was derived from Pb(Zr0.5Ti0.5)O3 and Pb(Mg2/3Nb1/3)O3 based compositions those obtained via the columbite method. The effect of MnO2 addition on microstructure, physical properties and piezoelectric properties were investigated. In this study, the composition with PZT/PMN ratio of 1:1 was selected. To observe the effect of MnO2 adding, its concentration was varied in range 0-10 mol%. Green pellets were sintered at temperature 1250oC for 4 hours. For piezoelectric investigation, the ceramics pellets were subjected to a poling process. The XRD results show that there is no phase transformation observed for all sintered PZT-PMN samples with presence of MnO2. The SEM micrographs reveal that MnO2 can enhance sinterability as evidenced by lowering of porosity and increasing of grain size with increasing of MnO2 content. Increasing of linear shrinkage and apparent densities also confirmed such effect. Improvement of d33 from 28 to 114 pC/N could only found for MnO2 in range 0 to 4 mol%. For higher MnO2 content, there is only slightly increased. However, increasing of kp with increasing of MnO2 is clearly observed. While dielectric constant measured at room temperature and at frequency 1 kHz is higher for ceramics without MnO2 doping and it decreases with increasing MnO2 concentration. The temperature dependence of relative dielectric constant go to peak of value about 6000 at temperature around 180oC and shifting of these peaks with frequency can only be observed for samples with higher MnO2 content. This indicates a normal ferroelectric behavior for sample with lower MnO2 and there are converted to relaxor after MnO2 increased.

Abstract: Piezoelectric transformer (PT) is a combination of piezoelectric actuator and transducer, which serve as the primary side and the secondary side respectively. In the present study the disk – shaped (of 20 mm in diameter and 0.6 mm in thickness), unipoled radial mode piezoelectric transformer based on modified PZT-type solid solution was custom designed and fabricated. Different input and output area ratios of the PT were studied, namely: 21, 4, 1. The electrical properties like voltage step-up ratio, output power and temperature rise were measured for PT operating at the first resonance frequency. With the driving voltage of 20 VRMS, the 3 W output power, 165 VRMS output voltage an temperature rise of 20 0C was obtained for PT with the input/output area ratio of 1. The voltage step-up ratio of 12.5 was obtained for PT with input/output area ratio of 21.