阅读说明：本技术 一种基于压电效应的声表面波电场传感器件 (Surface acoustic wave electric field sensing device based on piezoelectric effect ) 是由 何金良 韩志飞 胡军 张波 于 2021-09-07 设计创作，主要内容包括：一种基于压电效应的声表面波电场传感器件,包括压电材料,压电材料一端的激振区设置激振电极,另一端的拾振区设置拾振电极,压电材料的激振区和拾振区之间的区域为传播区；激振电极的正极接激励源且其负极接地；拾振电极的正极与信号处理电路连接且其负极接地；激振电极和拾振电极均由两组叉指电极构成；当将传感器置于被测量电场中时,压电材料发生形变,从而导致声表面波的传播速度或频率发生变化,导致拾振电极接收到的信号发生变化,信号处理电路对该信号进行处理,即可以实现对电场的测量。本发明的器件具有宽电场测量范围和高灵敏度,体积小、成本低、制备简单,适用于电网及设备内部电场测量。(A surface acoustic wave electric field sensing device based on piezoelectric effect comprises a piezoelectric material, wherein an excitation area at one end of the piezoelectric material is provided with an excitation electrode, a vibration pickup area at the other end of the piezoelectric material is provided with a vibration pickup electrode, and an area between the excitation area and the vibration pickup area of the piezoelectric material is a propagation area; the positive pole of the exciting electrode is connected with an exciting source, and the negative pole of the exciting electrode is grounded; the positive pole of the vibration pickup electrode is connected with the signal processing circuit, and the negative pole of the vibration pickup electrode is grounded; the excitation electrode and the vibration pickup electrode are both composed of two groups of interdigital electrodes; when the sensor is placed in an electric field to be measured, the piezoelectric material deforms, so that the propagation speed or frequency of surface acoustic waves changes, signals received by the vibration pickup electrode change, and the signals are processed by the signal processing circuit, so that the electric field can be measured. The device has the advantages of wide electric field measurement range, high sensitivity, small volume, low cost and simple preparation, and is suitable for electric field measurement in power grids and equipment.)

1. A surface acoustic wave electric field sensing device based on piezoelectric effect comprises a piezoelectric material, wherein an excitation area at one end of the piezoelectric material is provided with an excitation electrode, a vibration pickup area at the other end of the piezoelectric material is provided with a vibration pickup electrode, and an area between the excitation area and the vibration pickup area of the piezoelectric material is a propagation area; the positive electrode of the excitation electrode is connected with an excitation source, and the negative electrode of the excitation electrode is grounded; the positive pole of the vibration pickup electrode is connected with the signal processing circuit, and the negative pole of the vibration pickup electrode is grounded; the excitation electrode and the vibration pickup electrode are both composed of two groups of interdigital electrodes; when the sensor is placed in an electric field to be measured, the piezoelectric material deforms, so that the propagation speed or frequency of surface acoustic waves changes, signals received by the vibration pickup electrodes change, the signal processing circuit processes the signals, and the electric field can be measured.

2. A surface acoustic wave electric field sensing device based on the piezoelectric effect as claimed in claim 1, wherein said piezoelectric material is an elongated strip.

3. A surface acoustic wave electric field sensing device based on piezoelectric effect as claimed in claim 1 or 2, characterized in that the piezoelectric material has a large electromechanical coupling coefficient, a small temperature delay coefficient and a low propagation loss.

4. A surface acoustic wave electric field sensing device based on piezoelectric effect as claimed in claim 1, wherein said piezoelectric material is a piezoelectric crystal.

5. A surface acoustic wave electric field sensing device based on piezoelectric effect as claimed in claim 1, wherein the excitation frequency of said excitation source is 40MHz-1 GHz.

6. A surface acoustic wave electric field sensing device based on piezoelectric effect as claimed in claim 1, wherein said signal processing circuit is composed of an oscillation circuit, a mixer circuit, a low pass filter amplifier circuit, a frequency measuring circuit and a temperature compensation circuit.

7. A surface acoustic wave electric field sensing device based on piezoelectric effect as claimed in claim 1, wherein sound absorbing material is attached to both ends of said piezoelectric material to absorb surface acoustic waves propagating to the end of the piezoelectric material and avoid interference of reflected waves.

8. A surface acoustic wave electric field sensing device based on piezoelectric effect as claimed in claim 7, wherein said sound absorbing material is a mixture of damping material and epoxy resin.

9. A surface acoustic wave electric field sensing device based on the piezoelectric effect as claimed in claim 1, wherein the piezoelectric material has a thickness of 100um-1mm, a width of 1mm-20mm and a length of 10mm-100 mm.

10. A surface acoustic wave electric field sensing device based on piezoelectric effect as claimed in claim 1, wherein the length of said propagation region is longer than the length of said excitation region and the length of said vibration pickup region, and the sensor sensitivity is adjusted by adjusting the length of said propagation region.

Technical Field

The invention relates to the field of electric field measurement, in particular to a surface acoustic wave electric field sensing device based on a piezoelectric effect.

Background

The real-time measurement of the information in the power grid has important significance for system running state monitoring, fault prediction, fault diagnosis and equipment state monitoring. In the power grid, the significance of the voltage signal is very important. The fingerprint characteristics of the voltage contain a large amount of information, and the monitoring of the steady-state information of the power grid and the extraction of the transient signal can be realized by measuring the voltage, so that an operation basis is provided for a power grid control end, and the safety and the reliability of the power grid are improved. The traditional voltage measurement means utilizes a mutual inductor to measure, and the measurement equipment is large in size and high in maintenance cost, can only be used for voltage measurement of key nodes, and cannot realize wide-range wide-area monitoring.

The inversion of the voltage signal by the electric field sensor is a new voltage measurement means. On the one hand, electric field sensor is small, with low costs, can arrange on a large scale, and on the other hand utilizes electric field sensor can carry out non-contact measurement, need not consider insulating cost, can not influence the electric energy quality simultaneously.

Common electric field sensors include those based on the electro-optic effect and MEMS electric field sensors. The electric field sensor based on the electro-optic effect is mature in application, high in sensitivity and wide in bandwidth. However, such sensors are limited to electro-optic crystals, have poor temperature stability, and are expensive in equipment. The MEMS electric field sensor measures an electric field by utilizing the electrostatic induction principle, has small volume and low cost, but has poor frequency response and higher power consumption. Therefore, it is necessary to design an electric field sensor with small size, low cost, wide measurement range and wide frequency band.

Disclosure of Invention

In order to solve the problems, the invention provides a surface acoustic wave electric field sensing device based on a piezoelectric effect, which achieves the purpose of measuring an electric field by measuring the change of the frequency or the speed of the surface acoustic wave.

A surface acoustic wave electric field sensing device based on piezoelectric effect. The piezoelectric vibration pickup device comprises a piezoelectric material, wherein an excitation area at one end of the piezoelectric material is provided with an excitation electrode, a vibration pickup area at the other end of the piezoelectric material is provided with a vibration pickup electrode, and an area between the excitation area and the vibration pickup area of the piezoelectric material is a propagation area; the positive electrode of the excitation electrode is connected with an excitation source, and the negative electrode of the excitation electrode is grounded; the positive pole of the vibration pickup electrode is connected with the signal processing circuit, and the negative pole of the vibration pickup electrode is grounded; the excitation electrode and the vibration pickup electrode are both composed of two groups of interdigital electrodes; when the sensor is placed in an electric field to be measured, the piezoelectric material deforms, so that the propagation speed or frequency of surface acoustic waves changes, signals received by the vibration pickup electrodes change, the signal processing circuit processes the signals, and the electric field can be measured.

Preferably, the piezoelectric material is in the form of a strip.

Preferably, the piezoelectric material has a large electromechanical coupling coefficient, a small temperature delay coefficient and a low propagation loss.

Preferably, the piezoelectric material is a piezoelectric crystal.

Preferably, the excitation frequency of the excitation source is 40MHz-1 GHz.

Preferably, the signal processing circuit is composed of an oscillation circuit, a mixing circuit, a low-pass filtering and amplifying circuit, a frequency measuring circuit and a temperature compensation circuit.

Preferably, sound absorption materials are attached to two ends of the piezoelectric material, and the sound surface waves transmitted to the tail end of the piezoelectric material are absorbed, so that interference of reflected waves is avoided.

Preferably, the sound absorbing material is formed by mixing a damping material and an epoxy resin.

Preferably, the piezoelectric material has a thickness of 100um-1mm, a width of 1mm-20mm, and a length of 10mm-100 mm.

Preferably, the length of the propagation area is longer than that of the excitation area and the vibration pickup area, and the sensitivity of the sensor is adjusted by adjusting the length of the propagation area.

The invention has the beneficial effects that:

the sensor designed by utilizing the inverse piezoelectric effect of the piezoelectric material and the propagation characteristics of the surface acoustic wave realizes the measurement of the electric field, and has simple structure and easy processing. Because the wavelength of the surface acoustic wave is short, the size of the surface acoustic wave sensor is far smaller than that of an electromagnetic wave device in the same frequency band, and the miniaturization of the sensor is realized. Because the surface acoustic wave sensor concentrates energy on the surface of the medium, the surface acoustic wave sensor is very sensitive to the change of an external object to be measured, and has high precision and high sensitivity. Because the piezoelectric material has high temperature stability and high characteristic frequency, the device has high temperature stability and wide frequency band and is suitable for various application scenes in a power grid.

Drawings

FIG. 1 is a schematic structural diagram of a surface acoustic wave electric field sensing device based on piezoelectric effect according to the present invention;

FIG. 2 is a schematic diagram of the operation principle of the surface acoustic wave electric field sensing device based on the piezoelectric effect.

In the figure, 1, a piezoelectric material; 2. an excitation electrode; 3. a vibration pickup electrode; 4. a sound absorbing material; 5. a signal processing circuit.

Detailed Description

The present invention will be described in detail below with reference to the accompanying drawings.

A surface acoustic wave is an elastic wave propagating on the surface of a medium and can be generated on a piezoelectric material by interdigital electrodes. According to the propagation characteristics of surface acoustic waves, the invention provides a surface acoustic wave electric field sensing device based on the piezoelectric effect, as shown in fig. 1. The piezoelectric vibration pickup device comprises a piezoelectric material 1, wherein two ends of the piezoelectric material 1 are respectively provided with an excitation electrode 2 and a vibration pickup electrode 3, the excitation electrode 2 and the vibration pickup electrode 3 are respectively composed of two groups of interdigital electrodes, each group of interdigital electrodes comprises a grounding electrode, and the rear end of the vibration pickup electrode 3 is connected with a signal processing circuit 5.

As shown in fig. 2, the piezoelectric material 1 is generally in the form of a strip, and is divided into three regions: an excitation area, a propagation area and a vibration pickup area. The propagation area is located between the excitation area and the vibration pick-up area. The length of the propagation area is generally longer than that of the excitation area and the vibration pickup area, and the sensitivity of the sensor can be adjusted by adjusting the length of the propagation area. The lengths of the excitation area and the vibration pickup area depend on the size of the interdigital electrode and the parameters of the surface acoustic wave.

The piezoelectric material 1 is generally made of a piezoelectric crystal such as quartz. The size of the piezoelectric material can influence the propagation characteristic of surface acoustic waves, and the piezoelectric materials with different sizes can be selected according to different requirements. The piezoelectric material is generally between 100um-1mm thick, 1mm-20mm wide and 10mm-100mm long. The thinner the thickness, the smaller the width and the longer the length, the larger the sensor response, but the thicker the width and the longer the length, the lower the mechanical strength of the sensor and the increased difficulty of the preparation. The piezoelectric material is required to have a large electromechanical coupling coefficient (the larger the better), a small temperature retardation coefficient (the smaller the better) and a low propagation loss (the smaller the better) in order to secure the propagation efficiency of the surface acoustic wave.

The excitation electrode 2 is located in an excitation region of the piezoelectric material 1. The positive electrode (pressurizing electrode) of the excitation electrode 2 can be directly connected with a signal source, and can also receive an external signal through an antenna to carry out excitation. The negative electrode of the excitation electrode 2 is grounded. When an alternating current signal with a certain frequency is applied to the excitation electrode 2, an electric field is generated between the interdigital electrodes, the piezoelectric material is deformed by the inverse piezoelectric effect, and the piezoelectric material is converted into surface acoustic waves which are transmitted along the surface of the piezoelectric material. The surface acoustic wave frequency is equal to the applied excitation frequency, typically 40MHz-1 GHz.

The vibration pickup electrode 3 is located in the vibration pickup region of the piezoelectric material 1. The positive electrode (signal electrode) of the vibration pickup electrode 3 is connected with the signal processing circuit 5, and the negative electrode is grounded.

The sound absorption material 4 can be attached to two end parts of the piezoelectric material 1 and used for absorbing surface acoustic waves transmitted to the tail end of the piezoelectric material 1 and reducing interference of reflected waves. The sound absorbing material 4 is obtained by mixing a damping material and an epoxy resin.

The signal processing circuit 5 is used for processing signals picked up by the vibration pickup electrode 3 and consists of an oscillating circuit, a mixing circuit, a low-pass filtering and amplifying circuit, a frequency measuring circuit and a temperature compensating circuit.

When a sinusoidal signal is applied to the interdigital electrode of the excitation electrode 2, the sinusoidal signal excites a surface acoustic wave on the piezoelectric material 1, and an electric signal is converted into an acoustic signal. When the surface acoustic wave is transmitted to the vibration pickup electrode 3 (also an interdigital electrode) for vibration pickup arranged at the other end of the piezoelectric material 1 along the medium, the vibration pickup electrode 3 converts the surface acoustic wave into an electric signal.

The piezoelectric material 1 is deformed by an electric field. When the sensor of the present invention is placed in an electric field, the piezoelectric material 1 deforms, which causes a change in the propagation speed or frequency of the surface acoustic wave, and thus the signal received by the vibration pickup electrode 3 changes. The measurement of the electric field can be achieved by processing the signal by the back-end circuit.

The technical solutions described above only represent the preferred technical solutions of the present invention, and some possible modifications to some parts of the technical solutions by those skilled in the art all represent the principles of the present invention, and fall within the protection scope of the present invention.