Piezoelectric Transformer Research Articles

Comparison between piezoelectric transformer and electromagnetic transformer used in electronic circuits

This paper presents study, modeling and simulation of the piezoelectric material works as transformer (piezoelectric transformer (PT)) in power electronic circuits, comparisons are made with the regular transformer (iron core) works in the same circuit, the tested circuit is the full bridge converter which used in the simulation as dc power supply circuit. As a result, a detailed simulation for both the piezoelectric transformer and traditional transformer are achieved, as well as the output voltage from the dc power supply is tested by varying the load resistance. The dc power supply circuit has been simulated using PSIM (V9.1) power electronic circuit simulation software.

Low-Voltage Plasma Jet With Piezoelectric Generator: Preliminary Evaluation of Decontamination Capabilities

This article deals with the proof of concept and the preliminary evaluation of decontamination performances obtained with a plasma jet generated by a piezoelectric transformer (PT). This low-voltage supply solution (<; 10 V) is investigated as a plasma jet device, compact and safe solution for the decontamination of medical thermo-sensitive devices. The principle of the piezoelectric generator is presented, followed by the optical s-protocol conditions for the bactericidal effect observations, and finally the reduction rates obtained on Pseudomonas aeruginosa and Staphylococcus aureus bacteria strains with an argon plasma jet at atmospheric pressure about 2.5-W electrical input power.

Using of direct piezo-discharge in generation of plasma-activated liquid media

This article shows the possibility of plasma-activated liquid media generation using the least energy-consuming source of low-temperature plasma, based on the use of a piezoelectric transformer. The experiments determined the possibility of producing reactive oxygen and nitrogen species in deionized water and culture media. The concentrations of H2O2 and NOx were estimated depending on the energy deposition.

Finite element simulations of step-down PZT-based piezoelectric transformer with modifying vibration and frequency characteristics

The finite element method (FEM) is widely used in engineering, and the ANSYS program is accepted by researchers. In this paper, a step-down PZT-based (PZT-85) piezoelectric transformer is designed to explore the vibration and frequency characteristics of a piezoelectric transformer. The simulation results are in good agreement with the experimental measurements, despite small differences due to human and equipment errors. The results indicate that the combination of FEM simulations and experiment is effective for designing piezoelectric devices.

Time-resolved characterization of a free plasma jet formed off the surface of a piezoelectric crystal

When a piezoelectric transformer (PT) is actuated by a low input voltage (∼10 V), electromechanical coupling leads to a very high (∼103 V) surface potential at the distal end that can ionize the surrounding gas and lead to a plasma jet emanating from the surface. PTs are attractive for non-equilibrium plasma generation because of their simple operation, low required input voltage, and low power consumption. In this work, the time-resolved characteristics of the free surface plasma jet generated by a PT operating in open air have been investigated. The temporal evolution of the PT-driven plasma was visualized by using an intensified CCD camera and plasma formation was correlated with the current behavior of the plasma jet. Notably, the plasma formation is a discrete process, appearing at a relatively fixed phase of the sinusoidal input, and the strongest plasma jet appears at the end of the positive half-cycle. Simultaneous measurements of the current show that the discharge current response is consistent with the chaotic mode for a plasma jet and appears statistically about a 1 μs earlier than plasma jet light emission, which indicates that there is a strong afterglow. With a low input voltage required for operation, these types of PT-driven plasma jets could have wide utility in emerging plasma applications beyond the laboratory, such as in healthcare and water treatment.

Equivalent circuit parameter extraction of low‐capacitance high‐damping PTs

Existing equivalent circuit extraction techniques are inaccurate for piezoelectric transformers (PTs) with low-input capacitance or high damping. A new method is presented, offering improved accuracy in both damping resistance and resonant frequency extraction compared with state-of-the-art methods. Effectiveness is evaluated on two sample PTs, with the proposed method achieving up to 84% decrease in error compared with previous methods.

Study of Characteristics of the Cold Atmospheric Plasma Source Based on a Piezo Transformer

In this paper, we study a compact source of low-temperature cold atmospheric plasma based on a piezoelectric transformer used as a high-voltage source. This device can produce a direct piezo-discharge in the atmosphere, a classical dielectric barrier discharge, and a discharge in a noble gas flow. We have estimated the rotational and vibrational temperatures of the N2 ions and the electron temperature in the discharge from the emission spectra for different modes of source operation. When the source operated with loads of two types (metal and liquid loads), the electric field strength distribution near the discharge gap was measured with a probe operating on the basis of the Pockels effect. The possibility of application of this device for electromagnetic field impact on biological objects and plasma-activated media is discussed.

2-D Modeling of Rosen-Type Piezoelectric Transformer by Means of a Polynomial Approach.

A 2-D semianalytical model using the Legendre polynomial approach was applied for modeling the piezoelectric transformer (PT). In the model, the mechanical displacements and the electric potential were expanded in a double series of orthonormal polynomials with an appropriate analytical form. Series and parallel resonance frequencies, input electrical admittance, and voltage gain were obtained for the PT. The results are in excellent agreement with both the numerical results calculated with a 3-D finite-element analysis and experimental ones. The approach is able to predict the behavior of a wide and a long PT.

Reducing the resonant frequency difference of piezoelectric transformers parallel system with mechanical coupling

The resonant frequency difference of piezoelectric transformers (PTs) with a classical parallel connection could worsen system performance, then the mechanical coupling of PTs was proposed to avoid the disadvantage. Experimental results showed that when the difference was relatively small, the performance of the classical parallel system and proposed mechanical coupling system was similar. However, when the difference increased, the maximum output power of a classical parallel system at a temperature rise of 20 °C reduced by 32.6% and that of mechanical coupling system reduced by 7.7%. This indicated mechanical coupling was better than classical parallel connection in improving the output power of PTs.

Design of High Efficiency Controller for Wide Input Range DC-DC Piezoelectric Transformer Converter

Owing to the increasing demand for low-power electronic devices, the need for miniaturized, light-weight power supplies with a high power density is growing. A piezoelectric transformer, which is a mechanical resonance-based power transformer, can meet these requirements. However, piezoelectric transformers are based on mechanical resonance, and the resonance characteristics depend on the output current, temperature, and other parameters. Thus, their efficiency may rapidly reduce with changes in the resonance characteristics under specific load and temperature conditions. Therefore, this study proposes a technique that estimating the optimal frequency by using the measurements of the input voltage and current phase difference of the piezoelectric transformer and regulating the output voltage using the duty cycle. Modeling and control system analyses are performed to address the control interference problem caused by the plurality of control variables and control outputs. To demonstrate the proposed technique, a 40 W prototype hardware device is developed. The efficiency improvement is confirmed, and the analysis is validated.

Tunable High-Power Multilayer Piezoelectric Transformer

Piezoelectric transformers (PTs) have been conventionally used in step-up high-voltage low-power applications such as liquid crystal display (LCD) backlighting for portable electronic devices. PTs have also been considered for step-down applications such as battery chargers for portable devices. In these applications, adapting the output impedance of the PT to meet the requirements of lower output voltages and higher output currents implies the design of PTs with larger number of output layers. Furthermore, these step-down applications require efficient operation of PT under a variety of output load conditions to meet the conditions of battery charging. Thus, strategies to adapt the PT to the variation of the output load are being pursued. In this article, a novel tunable piezoelectric transformer (TPT) for ac–dc and dc–dc high-power converters is presented. This TPT is designed to operate in the radial mode and is fabricated using cofired multilayer process. By introducing control layers into the design, the TPT is shown to provide desired features that include adjustable frequency response and flexible transfer ratio. Fabricated TPT exhibits high efficiency over 96% with an output power capability of 40 W when operating under its nominal load conditions.

ПОБУДОВА МАТЕМАТИЧНОЇ МОДЕЛІ БІМОРФНОГО П'ЄЗОЕЛЕКТРИЧНОГО ТРАНСФОРМАТОРА

Introduction. Piezoceramic transformers are most widely used in high-voltage sources of secondary power supply and in devices where a large voltage conversion ratio is needed, in particular, in medical technology. Purpose is to solve the problem of the excitation of transverse bending oscillations in bimorph piezoelectric transformer. The ultimate goal of mathematical modelling of physical state of oscillating piezoceramic elements consists in qualitative and quantitative description of characteristics and parameters of electric and elastic fields existing in them. Methodology. Mathematical model of piezoelectric transformers operation using transverse bending vibrations in a bimorph piezoelectric element is constructed with a minimal number of assumptions simplifying the real situation. This allows to state that the proposed construction scheme delivers mathematical models that are sufficiently adequate to real objects and physical processes that exist in them. Results. Construction and features of mathematical description of bimorph piezoelectric element, the principle of which is based on the use of axisymmetric transverse bending oscillations, are considered. The solution of the problem of transverse bending oscillations excitation in bimorph piezoelectric element by the difference of electric potentials is obtained. Originality. Mathematical model of disk bimorph piezoelectric transformer with symmetrical electrical loads in secondary electrical circuit taking into account a complete set of geometrical, phys-ical, mechanical and electrical parameters is built. Practical value. As a result of research of real device’s mathematical model a set of geometrical, physical, mechanical and electrical parameters of a real object can be determined which provides the realization of technical parameters of piezoelectric functional element specified in technical specifications. The cost of the saved resources is the commercial price of mathematical model.

ДОСЛІДЖЕННЯ ХАРАКТЕРИСТИК БІМОРФНИХ П’ЄЗОЕЛЕКТРИЧНИХ ПЕРЕТВОРЮВАЧІВ

Bimorph piezoceramic elements, in which elastic oscillations of transverse bending are excited, are used to solve a wide range of scientific and technical problems. The relevance of the use of various functional elements of piezoelectronics in power and informational systems is explained, first of all, by their high reliability, as well as small dimensions and weight, which greatly facilitates the solution of the problem of miniaturization of such systems. The technologies and devices that use the direct and / or reverse piezoelectric effect in the principles of their work are promising. The purpose of this article is to study the characteristics of a bimorph piezoelectric element. The main result of this article can be fixed as follows: the paper considers the technology of additional elements, which does not require any refinement of the piezoelement, and the change in the characteristics of the transducer is carried out due to the external circuits for the piezoelement. The influence of additional inductance and capacitance on the amplitude-frequency characteristics of the piezoelectric transducer is studied. The influence of additional resistance connected to piezoelectric transducer’s input on its amplitude-frequency characteristics is investigated. Manipulating the additional elements, you can have a significant effect on the energy of oscillatory motion of material particles of piezoelectric disk volume. The construction and mathematical model of a bimorph disk piezoelectric transformer with a symmetric electric load in a secondary electric circuit, constructed with a minimal number of assumptions, which simplify the real situation, are considered. In addition, using a mathematical model, the sensitivity of the characteristics of piezoelectric transformer to variations in the parameters of its design elements is easily determined. Having these dependencies, it is possible to make a rational choice of the technology for manufacturing a product. Thus, a qualitative mathematical model can significantly reduce the time and cost of developing new models of piezoelectric transformers.

AT-Cut Quartz Piezoelectric Transformers for Passive Voltage Gain in an RF Front-End

The purpose of this work is to assess the performance of an AT-cut quartz device as a two-port resonant transformer for near-zero power-consuming wake-up receiver applications. The device consists of two, coupled thickness-shear mode trapped-energy ~50 MHz resonators on a single quartz substrate. Passive voltage gain up to 84 V/V (referenced to $50\Omega $ ) is observed when the device is driven by a low-power signal (≤ −30 dBm) at resonance. This transformer offers high voltage gain suitable for use in the front-end of a near-zero-power wake-up receiver. Additionally, this work shows that connecting two coupled-resonator quartz devices in a parallel-input, series-output (PISOT) configuration provides improvements in voltage gain. A 17% increase in gain is demonstrated for PISOT over that of a single coupled resonant transformer for various load impedances. This work is the first use of quartz piezoelectric transformers (PTs) for passive voltage gain, and the highest open-circuit gain demonstrated in a two-port micromechanical PT.

Study of two-spring piezoelectric harvesters

The paper considers two piezoelectric harvesters, consisting of two springs, attached to a piezoelectric transformer, and having a common concentrated mass. Modeling has been done by means of ANSYS, whereas the horizontal deviation of the mechanical system has been obtained, and the charge, accumulated on the electrodes of the piezo plate has been calculated. An equivalent circuit has been drawn and experimental studies have been conducted in order to validate the developed model.

Piezoelectric Energy Harvesting From Roadways Based on Pavement Compatible Package

Scavenging mechanical energy from the deformation of roadways using piezoelectric energy transformers has been intensively explored and exhibits a promising potential for engineering applications. We propose here a new packaging method that exploits MC nylon and epoxy resin as the main protective materials for the piezoelectric energy harvesting (PEH) device. Wheel tracking tests are performed, and an electromechanical model is developed to double evaluate the efficiency of the PEH device. Results indicate that reducing the embedded depth of the piezoelectric chips may enhance the output power of the PEH device. A simple scaling law is established to show that the normalized output power of the energy harvesting system relies on two combined parameters, i.e., the normalized electrical resistive load and normalized embedded depth. It suggests that the output power of the system may be maximized by properly selecting the geometrical, material, and circuit parameters in a combined manner. This strategy might also provide a useful guideline for optimization of piezoelectric energy harvesting system in practical roadway applications.

Piezoelectric Disc Transformer Modeling Utilizing Extended Hamilton's Principle

Piezoelectric transformers (PTs) are resonant electromechanical voltage conversion devices used in a variety of applications including voltage boosting and galvanic isolation. They offer advantages over electromagnetic voltage transformers, including high energy density as well as the potential for monolithic fabrication, making them well suited to small-scale microelectromechanical applications. Among various PT topologies, circular discs lend themselves to microfabrication, and are considered here. In order to gain fundamental understanding of disc PT dynamics, this work applies the extended Hamilton's principle of variational calculus to the piezoelectric electric enthalpy, using cylindrical coordinates, in order to derive electromechanical constitutive equations for bulk disc transformers. The use of the Hamilton approach in this work supports the integration of mechanical tethers that physically support the disc, allowing the model to be applied to device designs that are compatible with monolithic microfabrication from sheets of bulk piezoelectric material. Using the integrated model, voltage gain (output voltage/input voltage) is predicted as a function of multiple variables including electrode area ratio, device size, tether stiffness, internal material damping, and output load impedance, and is compared against finite element numerical and experimental prototype results for verification. Prototype 4-mm diameter tethered disc PTs on the order of 0.002 cm3, two orders smaller than the bulk PT literature, were fabricated to validate the proposed model, and had peak voltage gains over 2.

A transverse traveling wave piezoelectric transformer

Piezoelectric transformers can be a promising candidate in isolated power converters to replace magnetic ones as they present high quality factor, high voltage gain and low electromagnetic compatibility issues. Herein a new topology of traveling wave piezoelectric transformer (TWPT) is proposed. Unlike conventional piezoelectric transformers, the proposed transformer uses progressive waves to carry out the electromechanical conversion. The main asset of the structure is the obtaining of a polyphase system of voltage at the output. Thus, associated with an appropriate converter circuit topology, it enables any kind of AC-DC or AC-AC power conversion. The proposed piezoelectric transformer consists in a multi-electrode ring architecture and uses transverse wave, i.e. the deformation is orthogonal to the propagation direction, to perform the electro-mechanical coupling. Furthermore an analytical modelling is exposed to describe the electro-mechanical behaviour of the transformer. The technique allows to obtain an admittance matrix that completely characterizes the coupling between all the electrodes and that can be used to simulate the transformer in electronic circuit software. With this model it is possible to predict numerically the voltages, currents, displacements and stresses in the piezoelectric transformer over time as a function of the geometrical and physical parameters of the materials in early design stage and it allows a co-design between the piezoelectric transformer and its power electronics circuitry. Finally, a prototype of the TWPT with four phase output voltage is presented to experimentally validate this new concept.

PLL controller for achieving zero‐voltage switching (ZVS) in inductorless half‐bridge drive piezoelectric transformer resonant power supplies

Inductorless half-bridge, piezoelectric transformer (PT) resonant power supplies require careful control if zero voltage switching of the MOSFETs is to be achieved. Here we describe how a phase-locked loop may be used to achieve this by ensuring adequate deadtime exists between the two MOSFETs to allow the PT input voltage to fully charge to the DC link. Experimental results demonstrate the operation of the system.

МАТЕМАТИЧНИЙ ОПИС БІМОРФНОГО П'ЄЗОЕЛЕКТРИЧНОГО ЕЛЕМЕНТА

The relevance of the use of various functional elements of piezoelectronics in power and informational systems is explained, first of all, by their high reliability, as well as small dimensions and weight, which greatly facilitates the solution of the problem of miniaturization of such systems. The technologies and devices that use the direct and / or reverse piezoelectric effect in the principles of their work are promising. The purpose of this article is to solve the problem of the excitation of transverse bending oscillations in bimorph piezoelectric element. With the help of a personal computer, it is possible to work out several combinations of geometrical, physical and mechanical parameters of a specific design of piezoelectric transformer within a few hours, and to find a combination of them that ensures the implementation of the specified parameters of the device. Manipulating geometrical parameters of electrodes and their location relative to each other, one can have a significant effect on the energy of oscillatory motion particular type of material particles of piezoelectric disk volume. This allows to reduce the number of experiments that are inevitably performed in the process of developing new devices. In addition, using a mathematical model, the sensitivity of piezoelectric transformer characteristics to variations in the parameters of its design elements is easily determined. Having these dependencies, it is possible to make a rational choice of the technology for manufacturing a product, that is, to choose from a number of technologies the least expensive one. Thus, a qualitative mathematical model can significantly reduce the time and cost of developing new models of piezoelectric transformers. The main result of this article can be fixed as follows: the construction and features of mathematical description of bimorph piezoelectric element, the operating principle of which is based on the use of axisymmetric transverse bending oscillations, are considered. The solution of the problem of transverse bending oscillations excitation in bimorph piezoelectric element by the difference of electric potentials is obtained.