Piezoelectric Ceramic Transformer Research Articles

Comparison of BSPT and PZT Piezoelectric Ceramic Transformers for High‐Temperature Power Supplies

High‐temperature power electronics is an advancing area of research, especially given the widespread availability of wide bandgap semiconductors. Herein, a suitability analysis of (1−x)BiScO3−xPbTiO3 (BSPT) as a material for high‐temperature piezoelectric transformers (PTs) is presented and compared to state‐of‐the‐art Pb(Zr1−xTix)O3 (PZT). Initially, both materials are compared using a variety of metrics to prove the suitability of BSPT as a material for constructing PTs specifically for high‐temperature applications. PTs based on the two materials are designed and fabricated, and then subsequently characterized using impedance measurements. Finally, half‐bridge resonant inverters are constructed using both PTs and the performance of each inverter measured over a range of ambient temperatures. The result of these experiments confirms the suitability of BSPT for PT applications and shows the excellent performance of BSPT PTs at temperatures in excess of that possible with PZT‐based PTs.

Piezoelectric Transformers: An Historical Review

Piezoelectric transformers (PTs) are solid-state devices that transform electrical energy into electrical energy by means of a mechanical vibration. These devices are manufactured using piezoelectric materials that are driven at resonance. With appropriate design and circuitry, it is possible to step up and step down the voltages between the input and output sections of the piezoelectric transformer, without making use of magnetic materials and obtaining excellent conversion efficiencies. The initial concept of a piezoelectric ceramic transformer was proposed by Charles A. Rosen in 1954. Since then, the evolution of piezoelectric transformers through history has been linked to the relevant work of some excellent researchers as well as to the evolution in materials, manufacturing processes, and driving circuit techniques. This paper summarizes the historical evolution of the technology.

Optimization Design and Load Characteristics of the Ring-Type Piezoelectric Ceramic Transformer

A new type of ring-type piezoelectric ceramic transformer consisting of two concentric piezoelectric ceramic rings polarized axially and radially is analyzed. When the electric load impedance is considered, the electromechanical characteristics of the piezoelectric transformer are studied. The dependency of the voltage gain, the efficiency (the ratio of the output over the input power) and the effective electromechanical coupling coefficient of the piezoelectric transformer on the geometrical dimensions are analyzed. Meanwhile, the load dependency of the electromechanical parameters of the transformer is also investigated. It is concluded that the electromechanical characteristics of the piezoelectric transformer are closely related with the geometrical dimensions and the load electrical impedance. The conclusions can be used for the optimization design of the ring-type piezoelectric ceramic transformers in the engineering applications.

Enhancement of Plasma-Driven System With Piezoelectric Transformer-Based Feedback Control Approaches and a Contactless Power Source

This paper proposes a plasma-driven system with piezoelectric transformer-based feedback control approaches along with a contactless power source. The research is motivated because many plasma-driven circuits employed the bulky components as resonant circuit and current feedback sensors. Hence, this study proposes to utilize one piezoelectric ceramic transformer to serve for both resonance tank and feedback devices in order to achieve low cost and design simplification. Moreover, since the plasma discharge often suffers the problem of high humidity and particle-polluted environment, a contactless power transfer circuit integrated with a high-frequency coil is developed as the power source, by which the electrode damage can be better prevented. To reach a better discharge quality and own a higher flexibility of regulating power, the study also completes a constant-power control mechanism and a phase-locked loop control. Both software simulations and hardware realization have been accomplished. Analysis results and experimental outcome help validate the practicality of the proposed approach.

Parameters and design optimization of the ring piezoelectric ceramic transformer

Main aim of the presented paper is the theoretical analysis and experimental verification of the transformation parameters for the new type of nonhomogeneously poled ring transformer. The input part is poled in the thickness direction and output part in the radial direction. Two transformer geometries are studied — the input part is at inner ring segment, or it is at the outer ring segment. The optimum electrode size aspect ratios have been found experimentally as [Formula: see text] for the ring with aspect ratio [Formula: see text]. The fundamental as well as higher overtone resonances were studied for the transformation ratio, the optimum resistive load, efficiency and no-load transformation ratio. Higher overtones have better transformation parameters compared to the fundamental resonance. The new type ring transformer exhibits very high transformation ratios up to 200 under no-load and up to 13.4 under a high efficiency of 97% at the optimum load conditions of 10 [Formula: see text]. Strong electric field gradient at the output circuit is applicable for the electrical discharge generation.

High power density NaNbO3-LiTaO3 lead-free piezoelectric transformer in radial vibration modes

In the present work, the sintering temperature was able to substantially influence the microstructure and electrical properties of the lead-free ceramic 0.88NaNbO3–0.12LiTaO3. This composition without any acceptor doping presents a high mechanical quality factor, Qm, value of 1469 and a high Curie temperature of 305 °C by optimizing the sintering temperature at 1330 °C. We applied this material to make a device of disk-shaped piezoelectric transformers with a ring–dot structure and further focused on investigating the characteristics of the piezoelectric transformers. With matching load, a maximum efficiency of 92% occurs in the fundamental mode, and the maximum voltage gains are 5.5 and 3.7 for the fundamental and third radial vibration modes, respectively. The experimental results show a maximum output power of 10.5 W with a temperature rise of 27 °C. It is noteworthy that a high output power density (as high as 32.8 W cm−3) was obtained under a maximum input voltage of 180 V, which is comparable to the performance of PZT in a piezoelectric ceramic transformer device.

Analysis on the Ring-type Piezoelectric Ceramic Transformer in Radial Vibration

A new type of ring-type piezoelectric ceramic transformer in radial vibration is studied. It is composed of two concentric piezoelectric ceramic thin rings polarized axially and radially. Based on the electromechanical equivalent circuit, when the dielectric loss of the piezoelectric ceramic materials and the mechanical contacting loss between the input and the output piezoelectric rings are taken into account, the electromechanical characteristics of the piezoelectric transformer are studied. The dependence of the voltage gain, the power gain, or the efficiency (the ratio of the output power over the input power) and the effective electromechanical coupling coefficient on the geometrical dimensions are analyzed. Meanwhile, the load dependence of the electromechanical parameters of the transformer is also investigated. Some prototypes of the piezoelectric transformers are designed and made. The resonance/antiresonance frequency and the voltage gain are measured. It is shown that the measured electromechanical parameters are in good agreement with the theoretical results. The conclusions can be used for the optimization design of the ring-type piezoelectric ceramic transformers in the engineering applications.

Application of Piezoelectric-Transformer-Based Resonant Circuits for AC LED Lighting-Driven Systems With Frequency-Tracking Techniques

This paper proposes an application of piezoelectric transformer (PT) based inverters for alternating current (ac) light-emitting diode (LED) lighting-driven systems with a new resonant topology and frequency-tracking technique. This proposed architecture comprises a full-bridge phase-shift inverter with a PT-based C-L-C series resonant circuit, piezoelectric ceramic transformers, and a microwinding resonant transformer to extend the range of operation frequency, hence achieving a two-terminal alternating voltage to drive ac LED arrays while stabilizing the resonant characteristics. In this system design, a frequency-tracking mechanism is also integrated into the field-programmable gate array controller to improve operation efficiency. Since only the secondary current of the resonant transformer is required for the controller, the circuit implementation is simple and additional sensor devices can be largely saved. Moreover, by considering that the frequency-gain characteristics of PTs may be affected due to temperature changes; the controller is designed to adjust the operation frequency swiftly in order to restrict the temperature effect. This proposed method has been verified on modular ac LED lighting systems. Test results confirm the feasibility of the method for lighting system applications.

The Research of Atmospheric Pressure Cold Plasma Jet Generated by Auto-Excited-Pulsed DC Discharge

In order to obtain stable cold plasma jet under atmospheric pressure condition, we designed a high-voltage DC power supply based on the principle of multilayer piezoelectric ceramic transformer (MPT). At the same time, we developed a cold plasma jet device that its shape is similar to the gun structure. The total weight of device, including the power supply and the generator, is less than 500 g. In the experiments of argon plasma under atmospheric pressure, current–voltage measurements show that the discharge actually appears periodically pulsed with a frequency of about 30 kHz. The discharge current has a pulse-width that is about 100 ns, while its peak value reaches about 32 mA. The maximum length of the plasma is about 3 cm. The further study showed that the discharge current pulse frequency is determined by the ion drift mechanism.

Design of Low-Voltage Power Supply Drive Circuit Based on the Piezoelectric Ceramic Transformer

The piezoelectric ceramic transformer has the advantages of high conversion efficiency, high pressure, electromagnetic compatibility,etc.It overcomes the shortcomings of large electromagnetic interference, low conversion efficiency , a large volume, etc. Using IR2184,the paper designs piezoelectric ceramic transformer full-bridge driver circuit. It greatly improves the conversion efficiency of the power system and power.

Disc piezoelectric ceramic transformers.

In this contribution, we present our study on disc-shaped and homogeneously poled piezoelectric ceramic transformers working in planar-extensional vibration modes. Transformers are designed with electrodes divided into wedge, axisymmetrical ring-dot, moonie, smile, or yin-yang segments. Transformation ratio, efficiency, and input and output impedances were measured for low-power signals. Transformer efficiency and transformation ratio were measured as a function of frequency and impedance load in the secondary circuit. Optimum impedance for the maximum efficiency has been found. Maximum efficiency and no-load transformation ratio can reach almost 100% and 52 for the fundamental resonance of ring-dot transformers and 98% and 67 for the second resonance of 2-segment wedge transformers. Maximum efficiency was reached at optimum impedance, which is in the range from 500 Ω to 10 kΩ, depending on the electrode pattern and size. Fundamental vibration mode and its overtones were further studied using frequency-modulated digital holographic interferometry and by the finite element method. Complementary information has been obtained by the infrared camera visualization of surface temperature profiles at higher driving power.

Bar piezoelectric ceramic transformers.

Bar-shaped piezoelectric ceramic transformers (PTs) working in the longitudinal vibration mode (k31 mode) were studied. Two types of the transformer were designed--one with the electrode divided into two segments of different length, and one with the electrodes divided into three symmetrical segments. Parameters of studied transformers such as efficiency, transformation ratio, and input and output impedances were measured. An analytical model was developed for PT parameter calculation for both two- and three-segment PTs. Neither type of bar PT exhibited very high efficiency (maximum 72% for three-segment PT design) at a relatively high transformation ratio (it is 4 for two-segment PT and 2 for three-segment PT at the fundamental resonance mode). The optimum resistive loads were 20 and 10 kΩ for two- and three-segment PT designs for the fundamental resonance, respectively, and about one order of magnitude smaller for the higher overtone (i.e., 2 kΩ and 500 Ω, respectively). The no-load transformation ratio was less than 27 (maximum for two-segment electrode PT design). The optimum input electrode aspect ratios (0.48 for three-segment PT and 0.63 for two-segment PT) were calculated numerically under no-load conditions.

Concurrent operational modes and enhanced current sensitivity in heterostructure of magnetoelectric ring and piezoelectric transformer

A heterostructure possessing two concurrent operational modes: current sensing (CS) mode and current transduction (CT) mode and an enhanced current sensitivity associated with the CT mode is proposed by combining a magnetoelectric ring (MER) with a piezoelectric transformer (PET). The MER is a ring-shaped magnetoelectric laminate having an axially polarized Pb(Zr, Ti)O3 (PZT) piezoelectric ceramic ring sandwiched between two circumferentially magnetized, inter-magnetically biased Tb0.3Dy0.7Fe1.92 (Terfenol-D) short-fiber/NdFeB magnet/epoxy three-phase magnetostrictive composite rings, while the PET is a Rosen-type PZT piezoelectric ceramic transformer. The current sensitivity (SI) and magnetoelectric voltage coefficient (αV) of the heterostructure in the two operational modes are evaluated theoretically and experimentally. The CS mode provides a large SI of ∼10 mV/A over a flat frequency range of 10 Hz−40 kHz with a high resonance SI of 157 mV/A at 62 kHz. The CT mode gives a 6.4-times enhancement in resonance SI, reaching 1000 mV/A at 62 kHz, as a result of the amplified vortex magnetoelectric effect caused by the vortex magnetoelectric effect in the MER, the matching of the resonance frequencies between the MER and the PET, and the resonance voltage step-up effect in the PET.

Electromechanical characteristics of piezoelectric ceramic transformers in radial vibration composed of concentric piezoelectric ceramic disk and ring

A new type of piezoelectric ceramic transformer in radial vibration is presented. The piezoelectric transformer consists of a pairing of a concentric piezoelectric ceramic circular disk and ring. The inner piezoelectric ceramic disk is axially polarized and the outer piezoelectric ring is radially polarized. Based on the plane stress theory, the exact analytical theory for the piezoelectric transformer is developed and its electromechanical equivalent circuit is introduced. The resonance/anti-resonance frequency equations of the transformer are obtained and the relationship between the resonance/anti-resonance frequency, the effective electromechanical coupling coefficient and the geometrical dimensions of the piezoelectric transformer is analyzed. The dependency of the voltage transformation ratio on the frequency is obtained. To verify the analytical theory, a numerical method is used to simulate the electromechanical characteristics of the piezoelectric transformer. It is shown that the analytical resonance/anti-resonance frequencies are in good agreement with the numerical results.

Bulk piezoelectric ceramic transformers

In this contribution, we present a review on the various bulk piezoelectric ceramic transformers based on planar vibration modes. The studied transformer shapes include rectangular bar, rings and discs (e.g. disc ring dot) homogeneously poled in the thickness direction. Electrical parameters like transformation ratio, efficiency and input and output power are measured and modelled as a function of frequency and resistive load in the secondary circuit. Analytical modelling has been performed for the ‘Rosen type’ and ‘ring dot’ disc or ring transformers as well as for the bar transformers and several other geometries. Finite element analysis modelling has been performed for the set of other more complicated disc transformer geometries. An overview of the results on the studied transformers is presented, including data on transformation ratio, efficiency and optimum load.

Domain Engineered Piezoelectric Ceramic Transformers

Piezoelectric transformers (PT's) based on thin ceramics disc with the double “ring-dot” electrode design are studied on the domain engineered ceramics disc. Various possibilities of the domain volume distributions are experimentally prepared and the problems of non-homogeneous poling are discussed. Parameters of PT's such as transformation ratio and efficiency are measured as a function of frequency, resistive load and electrode geometry. The best transformation ratio and efficiency parameters were found for the homogeneously poled PT samples. Domain engineered poling direction distribution with alternating oppositely poled segments are the best among the non-homogeneously poled PT's, although the parameters are not better than for the homogeneously poled PT's.

압전 세라믹 변압기 특성에 관한 연구

In this paper, it is reviewed is to acquaint a circuit design with features of piezoelectric ceramic transformers(PT) and to show the general approach to the design of inverters utilizing PT as a circuit element. The description of the piezoelectric effect is not present here and can be easily found in numerous publications as well as complex equations and formulae. What is the most important to understand is that they are different -one cannot just change an electromagnetic transformer (EMT) for a piezoelectric one. Several examples of PT-based circuitry will help to start and use PT`s advantages most effectively.

AC–DC Converter Based on Parallel Drive of Two Piezoelectric Transformers

An AC–DC converter based on a parallel drive of two piezoelectric ceramic transformers was investigated. The transformers operate in a fundamental contour extensional vibration mode which has a large electromechanical coupling factor notwithstanding the use of a piezoelectric transversal effect. The converter includes Al electrolytic capacitors for smoothing circuits and metal oxide semiconductor field effect transistors (MOSFETs) for the switching and rectifying circuits. Maximum converter efficiency of 90% was obtained. The prospect of a low profile, highly efficient and high power (more than 50 W) AC–DC converter with piezoelectric transformers has been obtained through these experimental results.

A Piezoelectric Elements and Their Electronics Driving with Help of FPGA Circuits

The paper summarizes our experiences of various electric driving of piezoelectric elements (piezoelectric membranes, actuators, piezoelectric ceramic transformers, etc.) with help of the fast digital electronic components—particularly the Field Programmable Gate Arrays (FPGA), eventually the Digital Signal Processor (DSP). These components are often used in the piezoelectric applications with the extreme rate requirements—e.g. the driving ultrasonic piezoceramic motors by Pulse-width modulation (PWM) signal or the controlled elasticity of the piezoelectric materials.

Piezoelectric Ceramic Transformer Operating in Contour-Extensional Vibration Mode for AC-DC Converters

Piezoelectric Ceramic Transformer Operating in Contour-Extensional Vibration Mode for AC-DC Converters