Types of Piezoelectric Ceramic Transformer (1)

The theoretical research and application status of piezo ceramic disc transducer are discussed and commented comprehensively, and the existing problems are analyzed. Piezoelectric ceramic transformer is a new type of solid-state electronic device. It has the advantages of simple structure and process, small size, light weight, no electromagnetic noise, no electromagnetic winding, non-combustible, good integrity and large-scale production cost can be greatly reduced. It is widely used in the cold cathode tube, neon lamp tube, laser tube and X-ray tube, high voltage electrostatic spraying, high voltage electrostatic flocking and radar display tube is in the liquid crystal . At present, the traditional way to increase or decrease alternating voltage is to use electromagnetic transformer. It mainly consists of iron core and coils around iron core. Secondary coils achieve electromagnetic coupling through magnetic cores. In some power and high-power electronic applications, large electromagnetic transformers are very effective. However, with the development of science and technology and the miniaturization of electronic devices, many applications in the electronic industry need high-efficiency components with small size, so for small and high-efficiency transformers. However, due to its inherent reasons (such as skin effect loss of conductors, conduction loss of thin wires and relaxation loss of magnetic materials increase rapidly with the decrease of transformer size), it is difficult for existing electromagnetic transformers to achieve high efficiency and miniaturization. At present, electromagnetic transformers have become circuits. The largest electronic device on board is one of the biggest obstacles to miniaturization of electronic devices. In addition, the inherent magnetic leakage and electromagnetic radiation of electromagnetic transformer will pollute the environment, which is not conducive to industrial application. In order to overcome this problem and realize miniaturization of electronic devices, piezoelectric ceramic transformer is proposed. The piezoelectric ceramic transformer is basically composed of two piezoelectric ceramic resonators (or piezoelectric ceramic transducers and piezoelectric ceramic actuators) whose mechanical parts are coupled and circuit parts are insulated each other. It is a new type of voltage or current converter. Its working principle is different from that of traditional electromagnetic transformers. In the ceramic transformer, the coupling between primary and secondary is not realized by traditional electromagnetic effect, but by mechanical coupling and piezoelectric effect of piezoelectric material.

The development of piezoelectric ceramic transformer is closely related to the development of
piezo ceramic crystal materials. In the early stage of the development of piezoelectric ceramic transformer, because the research and production technology of piezoelectric ceramic materials are not advanced enough, its performance has also been greatly affected. The manufacturing technology of piezoelectric ceramics is in the primary stage, and the material performance is poor. Secondly, the working principle of piezoelectric ceramic transformer is based on the piezoelectric effect and mechanical vibration coupling of piezoelectric ceramic devices. In order to achieve a larger voltage and current gain of piezoelectric ceramic transformer, piezoelectric ceramic transformer should be in the state of mechanical resonance, but at that time, it is in the state of mechanical resonance. The research theory of the vibration mode of piezoelectric ceramic resonator is not yet mature. Thirdly, the research of the driving circuit of piezoelectric ceramic transformer is still in the initial stage. Many problems (such as frequency tracking and output voltage stability of piezoelectric ceramic transformer) were not solved perfectly at that time, which resulted in piezoelectric ceramic transformer. The instability of energy and its application are limited. The classification of piezoelectric ceramic transformers is mainly based on the working mode of piezoelectric ceramic transformers. At present, there are three main types of piezoelectric ceramic transformers, namely, piezoelectric ceramic transformers with length telescopic vibration mode (also known as Rosen type piezoelectric ceramic transformers), piezoelectric ceramic transformers with thickness telescopic vibration mode and radial direction. Vibration mode piezoelectric ceramic transformer.

Rosen Type Piezoelectric Ceramic Transformer

 Rosen type piezoelectric ceramic transformer, length telescopic vibration mode piezoelectric ceramic transformer is composed of a piezoelectric ceramic thin strip which generates transverse vibration mode and a piezoelectric ceramic thin strip which generates longitudinal vibration mode. When an alternating voltage of a frequency and a certain range is added to the primary end of a piezoelectric ceramic transformer, due to the inverse piezoelectric effect of the piezoelectric ceramic material, the length stretching vibration will occur at the input end of the piezoelectric ceramic material, i.e. the thin strip of the piezoelectric ceramic with thickness polarization. The vibration direction is perpendicular to the polarization direction and belongs to the transverse effect vibration. When the frequency approaches the resonant frequency of the oscillator, the displacement amplitude is the largest. The primary vibration of the transformer will be transmitted to the secondary of the transformer.with the help of the positive piezoelectric effect of the piezoelectric ceramic material, an alternating voltage will be generated at both ends of the transformer. The magnitude of the alternating voltage depends on the geometric size and vibration mode of each part of the piezoelectric transformer. In addition, it can be seen that in the secondary output part of Rosen type piezoelectric ceramic transformer, the polarization direction of the piezoelectric oscillator is consistent with its vibration direction, so it is a longitudinal vibration mode, i.e. stiffness vibration mode. Generally, the longitudinal length of Rosen type piezoelectric ceramic transformer is much longer than that of Rosen type piezoelectric ceramic transformer. The output voltage of Rosen type piezoelectric transformer is much larger than the input voltage because of its inherent high voltage gain. Rosen type piezoelectric transformer is often called high voltage piezoelectric transformer. In addition, Rosen type piezoelectric ceramic transformer belongs to high resistance type transformer. One of the applications of Rosen type piezoelectric ceramic transformer is to drive high voltage lamps, such as cold cathode fluorescent lamps for LCD ,vibration mode piezoelectric ceramic transformer.