Types of Piezoelectric Ceramic Transformer (2）

Views: 12 Author: Site Editor Publish Time: 2019-09-26 Origin: Site

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Other forms of piezoelectric ceramic transformer

In addition to the above three commonly piezoelectric ceramic transformers, other types of piezoelectric ceramic transformers have been developed, the structure of which is similar to the above three types, but some innovations have been made in some aspects to make piezoelectric ceramic transformers. Some of the features have been improved.

The third-order vibration mode Rosen-type piezoelectric ceramic transformer with two inputs overcomes the problem of the influence of the output electrode on the transformer in the Rosen-type piezoelectric ceramic transformer (the output electrode of the conventional Rosen-type piezoelectric ceramic transformer is located at the displacement wave of its vibration) In the abdomen, it is easy to affect the vibration and frequency characteristics of the transformer.it proposed a so-called third-order vibration mode Rosen-type transformer. The input end of the transformer is composed of two materials and the same transverse vibration mode. The piezoceramic elements ring piezoelectric ceramic is composed of slender strips, the output end is located between the two input piezoelectric ceramics, and the output electrode is located at the geometric center of the transformer. By selecting the material and geometrical dimensions of the input and output parts of the transformer, the three components of the transformer are respectively resonated to half. The wavelength resonance state, so the geometric center is just the displacement node, and the output connection line does not affect the vibration state of the transformer. The displacement and stress distribution of such a piezoelectric transformer, the arrow indicates the polarization direction of the piezoelectric ceramic . In the third-order vibration mode

The output impedance of the Rosen-type piezoelectric ceramic transformer is only one quarter of that of the conventional first-order vibration mode piezoelectric ceramic transformer, so that it can output higher electric power.High-power multilayer piezoelectric ceramic transformer.In recent years, piezoelectric ceramic transformers have been widely used in the backlights for color liquid crystal . With the large size of liquid crystal display screens, the demand for high-power backlight power supplies is urgent, requiring piezoelectrics ceramics of 10 W and ceramic transformers. In order to realize the miniaturization and high power of piezoelectric ceramic transformers, in addition to the development and use of high-power piezoelectric ceramic materials, Japanese experts have developed a high-power multilayer piezoelectric ceramic transformer.

It is actually a superposition of multiple rosen-type piezoelectric ceramic transformers. At the primary end, the piezoelectric plate transducer is polarized along the thickness direction. At the secondary end, the pressure of electric ceramic is polarized along the length. The alternating electric field is applied at the primary end. Due to the inverse piezoelectric effect, the length of the piezoelectric ceramic will be caused to expand and contract, and the electrical energy will be converted into mechanical energy. At the secondary end, positive piezoelectric is used. then convert mechanical energy into electrical energy, and output high voltage. A prominent feature of multilayer piezoelectric ceramic transformer is that when the thickness of piezoelectric ceramic transformer is constant, its boost ratio is proportional to the number of layers of the transformer. The transformer is easy to be flat, which is especially suitable for the surface assembly requirements of ultra-thin power. The high-power multilayer piezoelectric ceramic transformer developed has the advantages of small size and high boost ratio, and its output power can be more than 10 W. The backlight power supply for color liquid crystal displays can also be applied to high-voltage power for electronic products such as copiers, facsimile machines, and image scanners (resolution cameras). At present, in general, the conversion efficiency of single-layer piezoelectric ceramic transformers is 85 %～90%, the conversion efficiency of the three-layer piezoelectric ceramic transformer is greater than 90%, which is greater than the conversion efficiency of the traditional electromagnetic transformer (60%~70%). In addition, compared with the traditional electromagnetic transformer, the thickness of the piezoelectric ceramic transformer is two-thirds of the electromagnetic transformer, the substrate size is one-half of the electromagnetic transformer, and the weight is two-thirds.

Disc-type single polarization piezoelectric ceramic transformer are basically composed of two parts, input and output, and the piezoelectric ceramic materials of the input and output sections are polarized in different directions. It is the same polarization direction, such as thickness and radial vibration mode piezoelectric ceramic transformer, the input and output parts are also separately polarized. For multilayer piezoelectric ceramic transformers with different polarization directions (such as Rosen type piezoelectric ceramic transformer) At the intersection of the input and output parts, stress concentration affects the performance of the piezoelectric transformer due to the polarization direction. In order to avoid this problem and increase the power capacity of the piezoelectric ceramic transformer, a single polarization direction has been proposed. A circular plate type piezoelectric ceramic transformer is consisting of a thickness-polarized piezoelectric ceramic thin circular plate. The upper electrode of the circular plate is divided into two parts, the middle solid circle part is the transformer output electrode, and the outer ring is transformer input electrode. The electrode below the disk is the common ground electrode of the transformer. It indicates the polarization direction of the ceramic. When at the input of the transformer (ie outside Ring) When an alternating voltage is applied and the signal frequency is equal to the radial resonance frequency of the piezoelectric ceramic ring, the transformer will generate strong radial vibration. Since the input and output terminals of the piezoelectric ceramic transformer are connected to each other, the transformer is the output part (the solid circle in the middle) also exhibits strong radial vibrations, which are converted to voltage at the output by the forward piezoelectric effect, thereby realizing the voltage transformation. By selecting the area between the input and output electrodes Compared, the electrical impedance of the input and output of the transformer can be changed to achieve the purpose of voltage conversion. Since the piezoelectric electromechanical coupling coefficient of the piezoelectric vibrator is larger than its transverse coefficient, high energy conversion efficiency and large output power can be realized. Ceramic resonators come in a variety of forms, so the types and forms of piezoelectric ceramic transformers are also diverse. In addition to the traditional piezoelectric ceramic transformers operating in the telescopic vibration mode, there are also working in shear vibration mode and bending vibration. Piezoelectric ceramic transformers with modes and composite vibration modes. It is foreseen that with piezoelectric ceramic materials and piezoelectric ceramics has the depth study of the theory of pieces, the type of piezoelectric ceramic transformer will be more new piezoelectric ceramic transformer will gradually enter the practical stage.