Type Piezoelectric Transformer Research Articles

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.

Piezoelectric PZT thin-film transformers with a ring–dot structure

In this study, we present the design, the modeling, the fabrication, and the characterization of ring–dot type piezoelectric thin-film transformers (PTFTs). The structure of the PTFTs was a simple circular plate of Pb(Zr,Ti)O3 (PZT) thin film on a Si layer with ring–dot top electrodes and it was suspended by four pantograph-shaped bridges. We estimated the performance of the PTFTs by finite-element method simulations. In accordance with the FEM simulation model, PZT thin films were deposited on silicon-on-insulator substrates and microfabricated into PTFTs with ring–dot structures. From the produced devices, an admittance circle measurement was carried out, enabling us to predict performance. The actual output characteristics of the PTFTs were clearly observed at a resonance frequency (f r) of 4.57 MHz. At this point, a voltage gain of 0.22 and a power density of 704 W cm−3 were measured, under a load resistance (R L) of 22 Ω.

МАТЕМАТИЧЕСКОЕ МОДЕЛИРОВАНИЕ ПЬЕЗОЭЛЕКТРИЧЕСКОГО ТРАНСФОРМАТОРА СТЕРЖНЕВОГО ТИПА

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 purpose of this article is to build a mathematical model of rod type piezoelectric transformer. Currently, there are no reliable and valid methods of constructing of mathematical models of piezoelectric transformers, which could be used as a theoretical basis for characteristics and parameters calculating of this class of functional elements of modern piezoelectronics. The main result of this article can be fixed as follows: mathematical model of rod type piezo-electric transformer, the principle of operation of which involves the use of longitudinal vibrations in prismatic rod, is obtained

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.

Effects of Thickness and Input/Output Area Ratio on Electrical Characteristics of Circular Ring/Dot Type Piezoelectric Transformer

Many types of piezoelectric transformer (PT) have been developed for more than 50 years. In this research, the voltage gain (V-gain) from circular ring/dot type PTs which have 2–3 mm thicknesses and 1–7 input/output area ratios (i/o area) was investigated under the criteria of 104–106 Hz input voltage (Vin) and 500–100,00 Ω connected load resistance (RL). Results showed that 1) The maximum V-gain was located near its 1st resonance frequency measured on input electrode, 2) The V-gain was significantly increased with i/o area and RL. 3) Large V-gain was obtained in high i/o area PT connected to large enough load resistance.

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

Electrical characteristics of central driving type piezoelectric transformers with different electrode distributing

In this study, three kinds of central driving type piezoelectric transformers, Types A, B and C with different electrode distributing were investigated by using impedance analyses. With the increase of the input electrode area, the resonant resistance of input section decreased and the effective electromechanical coefficient increased. With the decrease of the length of the generator section, the resonant resistance of generator section increased and the effective electromechanical coefficient decreased. The voltage step-up ratio increased with the increase of the ratio of the input and output resonant resistance. The temperature rise of Type A was lower because the impedance matching between the load resistance and the output impedance was achieved. Taking into consideration of the mechanical quality factor ( Q m), the output impedance ( Z out) and the temperature rise (Δ T) of each transformer, Type A with the input electrode length ratio of 1:1:1 could be selected as the optimum structure to drive the LCD backlight.

동일 방향으로 분극된 디스크형 압전변압기의 전기적 특성

For high voltage operation, a new type of piezoelectric transformer using radial vibration of disk, poled with the same direction was proposed. The piezoelectric ceramics was composed to PZT-PMN-PSN. The diameter and thickness of a disk type piezoelectric transformer were 45［mm］and 4［mm］, respectively The surface ratio of driving electrode and generating electrode of the piezoelectric transformer was 2 : 1. The resonance characteristics of input admittance, step-up voltage ratio and power transmission efficiency of the piezoelectric transformer were measured by varying the load resistance(0.1∼70［kΩ］). As a result, both resonance frequency and step-up voltage ratio increased with increasing load resistance. The step-up voltage ratio was reached more than 60 times under no load resistance. The maximum efficiency of 97% at load resistance of 2kΩ was obtained.

The Performances of Piezoelectric Transformer for Fluorescent T5 Lamp

The properties of circular type piezoelectric transformer for fluorescent T5 lamp are investigated as a function of area ratio of input part to output part. From the simulation result using FEM, as the area ratio increases, the voltage step-up ratio increases linearly. The voltage step-up ratio of output to input is about 1.6 when the area ratio is about 2. The new ballast using piezoelectric transformer is the type of series resonant half bridge inverter. As the results of performance test, when the input voltage is 220 V rms , the step-up ratio is about 1.6 for lighting the lamp. Also, lamp current and output power are 150 mA and about 26 W in steady state, respectively. The efficiency is about 93 %. It is concluded that the PT fabricated in this study is available to the ballast for T5 lamp.

Engineering resonance frequency charts of PZT rings of different sizes and at different clamping conditions

For developing ring type ultrasonic motors and piezoelectric transformers, the method by V. Stephenson for the computation of resonance frequency of piezoceramic rings was extended. Engineering charts of the resonance frequencies of PZT rings with different sizes and at different clamping conditions were constructed. The resonance frequencies obtained from the charts were in good agreement with the experiments. Some interesting features of the resonance frequency with respect to the ring dimensions (the outside and inside diameters. OD and ID) were found. The resonance frequency for rings with the same outside diameter decreased with decreasing OD/ID ratio. Clamping of the outer circumference of the ring reduced the resonance frequency. There was a minimum in the curve of the resonance frequency versus OD/ID, when the inside of the ring was clamped. These features provided methods to reduce the resonance frequency so as to miniaturize ultrasonic motors and other piezoelectric devices using PZT rings.

Properties of Alternately Poled Piezoelectric Transformers

A piezoelectric transformer has been developed for use as a step-up transformer that is built into the CCFL (cold cathode fluorescent lamp) inverter. The CCFL is used for LCD (liquid crystal display) backlight functions. We developed a new type of piezoelectric transformer which has an alternately poled structure. It is able to illuminate a CCFL by applying half of the input voltage of the Rosen type piezoelectric transformer.