Research On Characteristics And Application Of Single-layer Piezoelectric Transformer With Adjustable Step-up Ratio

Piezoelectric transformers are a kind of resonant electromechanical voltage conversion device,which is more advantageous than electromagnetic transformers in the demand for miniaturization of power supply equipment,It has very important applications in micro power supply,high voltage drive,plasma generator and so on.Compared with traditional electromagnetic transformers,piezoelectric transformers have the advantages of small volume,high power density,and high efficiency.And it usually designed in multilayers to obtain a large voltage transformation ratio while reducing the driving voltage.However,the multilayer piezoelectric transformer requires bonding,sintering,and other processes in the manufacturing process,which design is complicated.In addition,the volume of a multi-layer piezoelectric transformer is usually larger than a single-layer one under the premise of meeting the power requirements,and is not suitable for some miniaturization occasions.Therefore,in response to this problem,this study proposes a single-layer piezoelectric transformer that can achieve different step-up ratios.The piezoelectric transformer mainly works in planar expansion mode.The rectangular or circular design can be selected according to the needs,and counter electrode segmentation,polarization mode and the topological connection of the polarization area are designed and planned ingeniously.Therefore,a high voltage output with different step-up ratios can be obtained under low voltage excitation.The main research work of the thesis is as follows:(1)A single-layer piezoelectric transformer that can achieve different step-up ratio is proposed,and the effectiveness of the proposed design is verified through theoretical derivation and multi-physics coupling simulation.First of all,the equivalent circuit method and the finite element analysis method are used to analyze the characteristic parameters of the piezoelectric transformer;Secondly,starting from electrostatic analysis,dynamic analysis and Hamilton principle,the working principles of single-layer piezoelectric transformers with rectangular and circular topologies are discussed;Finally,combined with three-dimensional finite element simulation technology for multi-physics coupling simulation,the characteristics of displacement,stress distribution,step-up ratio,and matching load are analyzed.(2)According to the proposed sesign scheme,single-layer rectangular and circular piezoelectric transformers with different step-up ratios are fabricated,and the electrical performance of the piezoelectric transformers with different step-up ratios were tested experimentally.At first,the voltage gain,resonance frequency,input and output power,and transmission efficiency of each step-up ratio transformer under different loads were tested;Secondly,according to the electrical performance,select the optimal load that meets the piezoelectric transformer of each step-up ratio;Finally,the electric performance of the transformer under different driving voltages was tested under the optimal load.(3)A single-layer piezoelectric transformer with adjustable step-up ratio and hierarchical driving characteristics is proposed,which is applied to LED lamps and their arrays,and a hierarchical driving scheme for Photomultiplier Tube is designed.First,the piezoelectric transformers with different step-up ratios were tested to drive LED lights with corresponding number of step-up ratios.Secondly,test higher-power LED arrays to verify the effectiveness of the transformer’s graded drive;Finally,a hierarchical driving scheme that can be used for Photomultiplier tubes is proposed.