Rosen-type Piezoelectric Transformer Research Articles

Rosen-Type Piezoelectric Transformers Based on 0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3 Ceramic and Doped with Sb2O3.

In this study, the characteristics in the lead-free piezoelectric ceramic 0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3 (0.5BZT-0.5BCT) were investigated to assess its potential for Rosen-type piezoelectric transformers. This piezoelectric ceramic has a piezoelectric charge coefficient d33 of 430 pC/N, an electromechanical coupling factor kp of 49%, a dielectric constant εr of 2836, a remnant polarization Pr of 4.98 μC/cm2, and a coercive electric field Ec of 2.41 kV/cm. Sb2O3 was soft doped with 0.05, 0.1, 0.15, and 0.2 mol%, respectively, and exhibited excellent physical properties at 0.1 mol%. Based on this, a piezoelectric transformer was fabricated and measured, and it showed better output characteristics than pure 0.5BZT-0.5BCT. The amplification ratio (Vout/Vin) was optimized based on the device geometry and properties of the piezoelectric material. Moreover, the output characteristics of the Rosen-type piezoelectric transformer were simulated with the PSpice program. Output values of the fabricated and simulated piezoelectric transformers for the r vibrational frequency were compared and analyzed. Accordingly, the step-up amplification ratios Vout/Vin of the fabricated and simulated devices at the vibrational frequency were compared as well. This piezoelectric transformer could replace silicon steel transformers and be used for the creation of black light and for laptop chargers.

Low frequency Vibration Energy Harvester using Compliant Mechanism driven Rosen-type Piezoelectric Transformer

This paper represents an energy harvesting technique using a compliant mechanism driven Rosen type piezoelectric transformer from low frequency (3-10 Hz) reciprocal gripping motion. The finite element model of the compliant structure is synthesized using topology optimization implementing the density model and is coupled with a piezoceramic transformer to operate it by human hands. The mechanism can also be operated with the help of external mechanisms. As a case study, the proposed compliant mechanism is modelled considering acrylic plastic material. The mechanism can produce a maximum power of 62.7 μW for a 10 Hz gripping frequency while operating at its optimal conditions. The paper also discusses the resonance condition of the structure to check its marginal state. The harvested energy can be extracted across a load resistances attached at both primary and secondary side of the piezoelectric transformer.

Planar Piezoelectric Transformer-Based High Step-Down Voltage-Ratio DC–DC Converter

High step-down voltage-ratio converters are widely used in medium-/high-voltage systems, such as solar power equipment and electric charging station as auxiliary power supplies fed from the dc bus. Traditionally, magnetic transformer-based solutions with high turns ratio are implemented for voltage conversion and galvanic isolation. Instead of utilizing electromagnetic coupling, the high-voltage Rosen-type piezoelectric transformer (PT) provides an alternative solution with electro-mechanical coupling, whose equivalent circuit can be represented by a resonant circuit with an ideal transformer. Moreover, the high-voltage Rosen-type PT features natural mechanisms for high-voltage insulation, high-voltage conversion ratio, and a compact planar form factor, which are all beneficiary for a high step-down auxiliary power supply. This article renders a Rosen-type PT-based high step-down voltage-ratio converter with comprehensive analysis and detailed design procedure. To better understand the operating principle, electrical characteristics of the PT are first analyzed. Effects of input and output compensation components of the PT and their tolerance analysis are subsequently discussed to optimize the performance. After that, topologies of both the input inverter and the output regulation stages are selected. The proposed design is finally validated by a planar prototype with 10-mm height, 5 W full output power, 200 V to 1.5 kV input voltage, and 5 V regulated output voltage.

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.

A 15-mV Inductor-Less Start-up Converter Using a Piezoelectric Transformer for Energy Harvesting Applications

This paper presents an inductor-less start-up converter for a sub-100-mV energy harvester based on an Armstrong oscillator topology using a piezoelectric transformer and a normally ON MOSFET. Two models of the converter have been detailed and validated experimentally for the start-up phase and steady-state operation to, respectively, determine the minimum start-up input voltage and the voltage gain. The models have been validated experimentally in a setup associating the converter and a thermoelectric generator. Based on a Rosen-type piezoelectric transformer and off-the-shelf components, the proposed start-up topology begins to oscillate at 15 mV and achieves a 1-V output voltage at only 43 mV. Compared to the literature, the topology needs no inductive component and achieves self-starting operation with a smaller input voltage.

A 12 mV start-up converter using piezoelectric transformer for energy harvesting applications

This paper presents a novel topology of start-up converter for sub 100 mV thermal energy harvesting based on an Armstrong oscillator topology using a piezoelectric transformer (PT) and a normally-on MOSFET. Based on a Rosen-type PT and off-the-shelf components, the proposed startup topology begins to oscillate at 12 mV input voltage corresponding to a temperature gradient of 2°C and achieves 1 V output voltage with only 18 mV input voltage applied to the harvester.

Modeling of a ring rosen-type piezoelectric transformer by Hamilton's principle.

This paper deals with the analytical modeling of a ring Rosen-type piezoelectric transformer. The developed model is based on a Hamiltonian approach, enabling to obtain main parameters and performance evaluation for the first radial vibratory modes. Methodology is detailed, and final results, both the input admittance and the electric potential distribution on the surface of the secondary part, are compared with numerical and experimental ones for discussion and validation.

A comparison of 1D analytical model and 3D Finite Element Analysis with experiments for a Rosen-type piezoelectric transformer

This article is dedicated to the study of Piezoelectric Transformers (PTs), which offer promising solutions to the increasing need for integrated power electronics modules within autonomous systems. The advantages offered by such transformers include: immunity to electromagnetic disturbances; ease of miniaturisation for example, using conventional micro fabrication processes; and enhanced performance in terms of voltage gain and power efficiency. Central to the adequate description of such transformers is the need for complex analytical modeling tools, especially if one is attempting to include combined contributions due to (i) mechanical phenomena owing to the different propagation modes which differ at the primary and secondary sides of the PT; and (ii) electrical phenomena such as the voltage gain and power efficiency, which depend on the electrical load.The present work demonstrates an original one-dimensional (1D) analytical model, dedicated to a Rosen-type PT and simulation results are successively compared against that of a three-dimensional (3D) Finite Element Analysis (COMSOL Multiphysics software) and experimental results. The Rosen-type PT studied here is based on a single layer soft PZT (P191) with corresponding dimensions 18mm×3mm×1.5mm, which operated at the second harmonic of 176kHz. Detailed simulational and experimental results show that the presented 1D model predicts experimental measurements to within less than 10% error of the voltage gain at the second and third resonance frequency modes. Adjustment of the analytical model parameters is found to decrease errors relative to experimental voltage gain to within 1%, whilst a 2.5% error on the output admittance magnitude at the second resonance mode were obtained. Relying on the unique assumption of one-dimensionality, the present analytical model appears as a useful tool for Rosen-type PT design and behavior understanding.

Large Self-Biased Magnetoelectric Properties in Heterostructure of Graded-Magnetostrictive Layers and a Rosen-Type Piezoelectric Transformer

This paper develops a magnetoelectric (ME) heterostructure FeCuNbSiB/Ni/Rosen-type piezoelectric transformer (RPT)/Ni/FeCuNbSiB consisting of a RPT Pb(Zr <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1-x</sub> Ti <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> )O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> with its drive-end sandwiched between two graded-magnetostrictive layers of FeCuNbSiB/Ni. The graded-magnetostrictive layer FeCuNbSiB/Ni is made up of Fe-based nanocrystalline alloy FeCuNbSiB (Fe <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">73.5</sub> Cu <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Si <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">13.5</sub> B <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">9</sub> ) and pure Nickel (Ni). Due to the different magnetic characteristics of FeCuNbSiB and Ni (such as permeability, saturation magnetization and magnetostriction), the FeCuNbSiB/Ni layer exhibits an internal magnetic bias field, which results in the large self-biased ME properties. An amplified output voltage can be obtained between the two electrodes of the generator-end due to the step-up voltage-gain effect of the RPT. Consequently, the maximum zero-biased ME voltage coefficients of generator-end are ~4.06 V/Oe at the first resonance frequency of ~41 kHz, and ~4.22 V/Oe at the second resonance frequency of ~102 kHz. The results show that this heterostructure is of interest for high-sensitive magnetic field sensors.

Efficient Waveform Preservation of Discrete Spectrum Signals With Multilayered Piezoelectric Transformer

Transformation of square pulse signals by the multilayer Rosen type piezoelectric transformer (PT) is investigated with the goals to preserve the signal waveform and achieve maximum efficiency for power electronics and LED lighting applications. The voltage gain of the transformer is calculated from equations of linear piezoelectricity and motion for a broad frequency range that includes multiple resonant frequencies of PT. The transformation of the square pulse is simulated numerically by applying the voltage gain function to the Fourier spectrum of the input signal, and then, restoring the time-domain output signal from its spectrum. A half-bridge MOSFET amplifier is built to drive the PT in the experimental setup. The measurements of the input and output waveforms and their Fourier spectra verify the calculations. It is shown that the components of the spectrum and the waveform of the square pulse signal can be preserved in the output signal by using multiple resonant frequencies of the transformer. With the accurate match between the signal harmonics and the resonant frequencies of the transformer voltage gain, the square pulse signal provides higher output power than a sine or a square wave, provided that the dominant harmonics of all signals have the same amplitude.

Development of piezoelectric transformer-coupled solid state relays for electrical circuit control in railway systems

A solid state relay (SSR) is an electrical ON–OFF control device through which the delivery of electrical power to loads is switched either ON or OFF by a small control signal. The device serves the same function as a classical electromechanical relay (EMR) but carries no mechanical switching mechanism so that it has a faster switching time, a lower switching noise, a stronger tolerance to mechanical shock and vibration, a longer lifetime, a smaller size and a lighter weight. Photo-coupled SSRs (PcSSRs) are regarded as the most popular type of SSR nowadays. However, the susceptibility of PcSSRs to power surge and lightening often requires specific protections to ensure their normal operation and performance, especially for railway systems. To advance SSR technology for an improved electrical circuit control in railway systems, we have developed a novel type of SSR, called piezoelectric transformer-coupled SSRs (PTcSSRs), by utilising the high input–output electrical isolation property of a modified Rosen-type piezoelectric transformer (PT) for coupling between the input low-voltage dc–ac control circuit and the output high-voltage ac load circuit. In this paper, we report the design, development and performance of a PTcSSR having a 12 V dc input and a 40–240 V, 2 A, 50/60 Hz ac output, and compare the measured performance data with those of a commercial PcSSR used for electrical circuit control in modern railway systems. The development of the PT and its input–output circuit is also discussed.

Modeling and Simulation of Three Level Piezoelectric Transformer Converters

This paper proposes a modeling and simulation of three level piezoelectric transformer converters. The increasing utilization of piezoelectric transformers (PT) in power electronics requires fundamental analysis and design of PT power converters. In addition, the possibility of overcoming the essential limitations of PT power ability by a combined operation of PTs needs to be examined. These studies could provide wide opportunities for PT exploitation in power electronic circuits. The electrical circuit and model of piezoelectric transformers (PTs) ELS-60 is developed. Rosen-type PT and many other non-isolated conversion circuits have the inherit problem of the common neutral between the input and output that make it difficult to connect the output in series like the magnetic transformer. A new method based on the bootstrap method is proposed to solve the aforementioned problem. A new circuit for output summation of voltage level in the output side of each PT is developed. The impact of load and output filter capacitor on the conversion ratio and resonant frequency is discussed. The paper finally proposes a multilevel concept for many PT connected together for voltage summation. The method proposed can be applied to other multiple conversion circuits, which are based on common neutral between the input and output. The MATLAB/SIMULINK software used to design the required circuit diagram.

A Novel Method for Connecting Multiple Piezoelectric Transformer Converters and its Circuit Application

The electrical circuit and model of piezoelectric transformers (PTs) ELS-60 is developed. Rosen-type PT and many other nonisolated conversion circuits have the inherit problem of the common neutral between the input and output that make it difficult to connect the output in series like the magnetic transformer. A new method based on the bootstrap method is proposed to solve the aforementioned problem. A new circuit for output summation of voltage level in the output side of each PT is developed. The impact of load and output filter capacitor on the conversion ratio and resonant frequency is discussed. Experimental results based on one printed circuit board prototype of double-level PT and boost convertor validate the previous theoretical analysis and simulation results. The paper finally proposes a multilevel concept for many PT connected together for voltage summation. The method proposed can be applied to other multiple conversion circuits, which are based on common neutral between the input and output.

Generating Passive Compact Models for Piezoelectric Devices

In this letter, a model-order-reduction method for generating piezoelectric compact models is presented. An Arnoldi-based technique is used to create compact models from the system matrices generated by a piezoelectric finite-element solver. The proposed approach also preserves the passivity of the generated compact models. The modeling results of a Rosen-type piezoelectric transformer are presented. The transient and frequency responses of the devices can be accurately simulated by the compact models. Moreover, compared with the full-meshed simulations, the compact models give computational speed-ups of at least two orders of magnitude.

Variation of Piezoelectric Transformer Electrode by Oxidation in Piezoelectric Inverter with Driving Time

Multi layer piezoelectric transformer has an advantage of the high step-up ratio, high electromechanical coupling coefficient (Kp ) and high mechanical quality factor (Qm ). However, they are subject to the electrode-crack and the need for an increased sintering temperature make the electrodes costly. The electrode-crack correlates to electrode oxidation in multi layer piezoelectric transformers and it is attended with drop-off in efficiency. In this study, high-power Rosen-type piezoelectric transformer were manufactured, and then investigated about electrode oxidation according to lapse of time for 4 month. The basic composition of piezoelectric ceramics consists of ternary 0.01Pb(Ni1/3Nb2/3)O3-0.08Pb(Mn1/3Nb2/3)O3-0.91Pb(Zr0.505Ti0.495)O3.

Modeling the Effect of Operation Temperature on Characteristics of Rosen Type Piezoelectric Transformer

Modeling the Effect of Operation Temperature on Characteristics of Rosen Type Piezoelectric Transformer

Multimodal electromechanical model of piezoelectric transformers by Hamilton's principle

This work deals with a general energetic approach to establish an accurate electromechanical model of a piezoelectric transformer (PT). Hamilton's principle is used to obtain the equations of motion for free vibrations. The modal characteristics (mass, stiffness, primary and secondary electromechanical conversion factors) are also deduced. Then, to illustrate this general electromechanical method, the variational principle is applied to both homogeneous and nonhomogeneous Rosen-type PT models. A comparison of modal parameters, mechanical displacements, and electrical potentials are presented for both models. Finally, the validity of the electrodynamical model of nonhomogeneous Rosen-type PT is confirmed by a numerical comparison based on a finite elements method and an experimental identification.

ELECTRICAL PROPERTIES OF PIEZOELECTRIC TRANSFORMER USING PSN-PMN-PZT CERAMICS

ABSTRACT In this study, Pb(Sb1/2Nb1/2)O3-Pb(Mn1/3Nb2/3) O3-Pb(Zr0.49Ti0.51)O3 (abbreviated as PSN-PMN-PZT) composition ceramics was sintered at 1230∼1270°C for developing the composition for piezoelectric transformer. At the ceramic composition sintered at 1250°C, Density, electromechanical coupling factor (kp) and mechanical quality factor (Qm) showed the excellent values of 7.78[g/cm3], 0.59 and 1931, respectively, suitable for piezoelectric transformer application. The single layer Rosen-type piezoelectric transformers were also sintered at the sintering temperature of 1250°C and manufactured with the size of 48 × 10 × 2 mm3, respectively, using the composition ceramics. And then, their electrical properties were investigated according to the variations of frequency and load resistance. At the load resistance of 150 kΩ, the voltage step-up ratio of the transformers showed the maximum values at the vicinity of 68.4KHz. And also, at that load resistance, piezoelectric transformers showed the temperature rises of about 6°C at the output power of 5W. At transformer with high effective electromechanical coupling factor(keff) and high piezoelectric constant(d33), lower temperature increase was relatively appeared. And also, the piezoelectric transformer was reviewed for the voltage down of igniter type energy harvesting piezoelectric device.

Analyses of the Heat Dissipated by Losses in a Piezoelectric Transformer

In this paper, a new approach to the thermal management of piezoelectric transformers is proposed. Starting from the electromechanical equations, including mechanical and dielectrical losses, and knowing the piezoelectric material characteristics, an analytical model was developed and the theoretical profile of the heat sources was deduced. To check these theoretical points of view, a thermal characterization of a Rosen-type piezoelectric transformer was done. The temperature field on the surface of the PT was measured in thermal transient steps. Knowing the specific temperature, the experimental heat sources were obtained. As expected, they are related to the square modulus of the strain or stress profiles on the one hand and to mechanical losses on the other, which confirms the theoretical results. Experimental data and calculation results are matched for several resistance loads and frequencies tested.

Multilayer Rosen-type piezoelectric transformer prepared with Pb(Mg1/3Nb2/3)O3–PbTiO3 single crystal

A multilayer Rosen-type piezoelectric transformer with the size of 20 mm length, 4 mm width and 2.8 mm thickness has been fabricated using ferroelectric single crystal Pb(Mg1/3Nb2/3)O3–PbTiO3. The electrical properties of the prepared transformer were systematically investigated. Results show that the efficiency of this transformer can reach 92% and the voltage step-up ratio under open circuit exceeds 100. Comparing this with the single-layer Rosen-type transformer, we reported lower output impedance and larger step-up voltage ratios have been obtained under the same load resistance. Near the resonance frequency, this transformer has a much purer vibration mode and wider working bandwidth. Furthermore, this transformer can successfully drive a 0.5 W LCD backlight under a lower input voltage without obvious temperature rise. These global properties make this piezoelectric transformer a promising candidate for small power inverters and cryogenic applications.