阅读说明：本技术 一种基于悬臂梁的广义磁电效应能量转换方法 (Cantilever beam-based generalized magnetoelectric effect energy conversion method ) 是由 张嘉伟 付庚 王力 于 2020-12-21 设计创作，主要内容包括：一种基于悬臂梁的广义磁电效应能量转换方法,包括以下步骤：步骤1,将PVDF压电薄膜一端固定,以悬臂梁结构固定到亥姆霍兹线圈与电磁铁两极中间部位,使交流磁场与直流磁场方向相互垂直；步骤2,设置亥姆霍兹线圈发出的交流磁场,得出PVDF样品输出电压与直流磁场的关系；步骤3,设置直流磁场发生器产生的磁场,用电流放大器和锁相放大器得到电流响应,得出PVDF样品输出电压与交流磁场频率的关系；步骤4,用传感器和激光控制器组成的激光振动计系统测试PVDF压电薄膜振动参数,验证所研究的电磁效应是一种通过机械耦合相互作用的电磁耦合现象；具有磁电效应能量转换准确、便捷的特点。(A cantilever beam-based generalized magnetoelectric effect energy conversion method comprises the following steps: step 1, fixing one end of a PVDF piezoelectric film, fixing the PVDF piezoelectric film to the middle parts of two electrodes of a Helmholtz coil and an electromagnet in a cantilever beam structure, and enabling the directions of an alternating current magnetic field and a direct current magnetic field to be vertical to each other; step 2, setting an alternating current magnetic field emitted by a Helmholtz coil to obtain the relation between the output voltage of the PVDF sample and the direct current magnetic field; step 3, setting a magnetic field generated by the direct current magnetic field generator, and obtaining current response by using a current amplifier and a phase-locked amplifier to obtain the relation between the output voltage of the PVDF sample and the frequency of the alternating current magnetic field; step 4, testing the vibration parameters of the PVDF piezoelectric film by using a laser vibrometer system consisting of a sensor and a laser controller, and verifying that the researched electromagnetic effect is an electromagnetic coupling phenomenon through mechanical coupling interaction; the method has the characteristics of accurate and convenient magnetoelectric effect energy conversion.)

1. A cantilever beam-based generalized magnetoelectric effect energy conversion method is characterized by comprising the following steps:

step 1, fixing one end of a PVDF piezoelectric film, and fixing the PVDF piezoelectric film to the middle parts of two electrodes of a Helmholtz coil and an electromagnet in a cantilever beam structure so that the directions of an alternating current magnetic field and a direct current magnetic field are vertical to each other;

step 2, setting an alternating current magnetic field emitted by a Helmholtz coil to be 5Oe and 1000Hz, measuring a piezoelectric current induced by the magnetic field by using a current amplifier and a phase-locked amplifier at room temperature to obtain a current response, and obtaining the relation between the output voltage of the PVDF sample and the direct current magnetic field, wherein the magnetic field generated by the direct current magnetic field generator is from-2500 Oe to 2500 Oe;

step 3, setting the magnetic field generated by the direct current magnetic field generator to be 1000oe, setting the alternating current magnetic field to be 5oe, and changing the frequency from 10Hz to 1470Hz, and obtaining current response by using a current amplifier and a phase-locked amplifier to obtain the relation between the output voltage of the PVDF sample and the frequency of the alternating current magnetic field;

and 4, testing the vibration parameters of the PVDF piezoelectric film by using a laser vibrometer system consisting of a sensor and a laser controller, and verifying that the researched electromagnetic effect is an electromagnetic coupling phenomenon through mechanical coupling interaction.

Technical Field

The invention belongs to the technical field of magnetoelectric material energy conversion, and particularly relates to a cantilever beam-based generalized magnetoelectric effect energy conversion method. A magnetoelectric conversion method of a piezoelectric film based on a cantilever beam structure under an alternating current-direct current magnetic field.

Background

At present, with the rapid development of intelligent scientific technology and electronic computer application, a large number of sensors are needed to detect and process energy information and convert the energy information into signals compatible with a computer, so that a huge platform is provided for the development of magnetic sensors, and a magnetic sensing industrial chain with wide prospects is formed. The magnetic sensor is widely applied to various aspects such as smart power grids, geological exploration, natural disaster prediction, biomedicine, military equipment and the like, and particularly has an extremely important position in the field of magnetic field detection. In the current magnetic sensor, the magnetoelectric conversion method is mainly based on hall effect, magnetoresistance effect, fluxgate effect, magnetoelastic effect, spontaneous magnetoelectric effect of multiferroic material, and the like. However, the magnetoelectric conversion methods based on the above effects have respective advantages and respective disadvantages, and are mainly reflected in the aspects of low sensitivity, complex structure, high manufacturing cost, harsh use environment conditions, strong external interference and the like.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention aims to provide a cantilever beam-based generalized magnetoelectric effect energy conversion method, which is accurate and convenient in magnetoelectric effect energy conversion, solves the technical problems in the aspects of magnetic sensing sensitivity, magnetoelectric conversion rate and manufacturing process, and can be used for manufacturing a magnetic field sensor; the method realizes magnetoelectric response based on the piezoelectric film PVDF, the piezoelectric film PVDF generates charges under the action of Lorentz force generated by eddy current, realizes magnetoelectric energy conversion, and has the advantages of being passive, high in flexibility, high in piezoelectric performance and good in mechanical performance.

In order to achieve the purpose, the invention adopts the technical scheme that:

the invention adopts a solution casting method to prepare a PVDF film, and then the PVDF film is processed through the processes of polarization and magnetron sputtering to finally prepare a gold-plated piezoelectric film with a rectangular size and the size thickness of 28 mu_mThe length is 4cm, and the width is 1 cm; fixing the PVDF piezoelectric material in a cantilever structure, wherein Helmholtz coils are arranged at two sides of the PVDF piezoelectric material, an alternating-current magnetic field is provided by using the coils, the coils are connected with a voltage amplifier, and the voltage amplifier is controlled by a waveform generator; the PVDF piezoelectric material has two poles of electromagnet as DC magnetic field generator and one DC voltage sourceAre connected. In the experiment, the magnitude of the dc magnetic field was measured in the air gap between the two poles of the electromagnet by a tesla meter (f.w.5080), the direction of the dc magnetic field being perpendicular to the ac magnetic field generated by the helmholtz coil. The changing magnetic field generates eddy current in the sample, so the sample film vibrates up and down along the thickness direction under the Lorentz force generated by the eddy current, and the magnetoelectric effect is generated. The current response was obtained by measuring the magnetic field induced piezoelectric current with a current amplifier and a lock-in amplifier at room temperature.

A cantilever beam-based generalized magnetoelectric effect energy conversion method comprises the following steps:

step 1, fixing one end of a PVDF piezoelectric film, and fixing the PVDF piezoelectric film to the middle parts of two electrodes of a Helmholtz coil and an electromagnet in a cantilever beam structure so that the directions of an alternating current magnetic field and a direct current magnetic field are vertical to each other;

step 2, setting an alternating current magnetic field emitted by a Helmholtz coil to be 5Oe and 1000Hz, measuring a piezoelectric current induced by the magnetic field by using a current amplifier and a phase-locked amplifier at room temperature to obtain a current response, and obtaining the relation between the output voltage of the PVDF sample and the direct current magnetic field, wherein the magnetic field generated by the direct current magnetic field generator is from-2500 Oe to 2500 Oe;

step 3, setting the magnetic field generated by the direct current magnetic field generator to be 1000oe, setting the alternating current magnetic field to be 5oe, and changing the frequency from 10Hz to 1470Hz, and obtaining current response by using a current amplifier and a phase-locked amplifier to obtain the relation between the output voltage of the PVDF sample and the frequency of the alternating current magnetic field;

and 4, testing the vibration parameters of the PVDF piezoelectric film by using a laser vibrometer system consisting of a sensor and a laser controller, and verifying that the researched electromagnetic effect is an electromagnetic coupling phenomenon through mechanical coupling interaction.

The invention has the beneficial effects that:

the invention realizes the magneto-electric energy conversion based on the electric charge generated by the PVDF piezoelectric material under the action of the Lorentz force generated by eddy current, and does not need an external excitation power supply, thereby achieving the purpose of passive detection.

The material selected by the invention is the gold-plated PVDF film piezoelectric material, and has high flexibility, high piezoelectric performance and good mechanical performance compared with a fragile piezoelectric ceramic material with limited strain level.

The research method of the invention does not compound the piezoelectric material and the magnetoelectric material to generate the magnetoelectric effect, but utilizes the magnetoelectric-elastic-electric coupling of the piezoelectric material taking strain as a medium, and the research method of the nonmagnetic phase opens up a new way for the research of the magnetoelectric energy conversion method.

Drawings

Fig. 1(a) is a partial schematic view of a generalized magnetoelectric effect energy conversion method testing apparatus according to an embodiment of the present invention.

FIG. 1(b) is a schematic top end view of FIG. 1(a) according to the present invention.

Fig. 2 is a schematic diagram of a PVDF piezoelectric film sample under the action of an ac magnetic field according to an embodiment of the present invention.

Fig. 3 is an overall view of a test experiment platform of the generalized magnetoelectric effect energy conversion method according to the embodiment of the present invention.

FIG. 4 shows an embodiment of the present invention in determining an AC bias magnetic field B_acUnder the condition that the frequency of 5Oe is 1kHz, the magnetoelectric voltage and a direct current bias magnetic field B_dcGraph of variation relation of (-2500Oe to 2500 Oe).

Fig. 5 is a graph of experimental measurement results of magnetoelectric voltage of the PVDF piezoelectric film provided by the embodiment of the invention in the range of the alternating current magnetic field frequency from 10Hz to 1470 Hz.

Wherein: the method comprises the following steps of 1-PVDF film sample, 2-Helmholtz coil, 3-magnet, 4-experiment base, 5-sample clamp, 6-Hall probe, 7-Tesla meter, 8-voltage amplifier, 9-waveform generator and 10-direct current voltage source.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings and examples.

Referring to fig. 1(a) and 1(b), a generalized magnetoelectric effect energy conversion method based on a cantilever beam comprises a PVDF film sample 1, wherein the PVDF film sample is clamped between two poles of an electromagnet 3 on an experiment base 4 in a cantilever beam structure, the electromagnet is driven by a direct current voltage source 10 to generate a direct current magnetic field, and the maximum amplitude is 3500 Oe. The helmholtz coil 2 is connected to a voltage amplifier 8, and an alternating magnetic field is supplied by the helmholtz coil 2 (maximum amplitude of 30 Oe). In the experiment, the magnitude of the dc magnetic field, which is perpendicular to the ac magnetic field generated by the helmholtz coil 2, was measured in the air gap between the two poles of the electromagnet by a tesla meter (f.w.5080) 7. When an alternating magnetic field passes through the PVDF film sample 1, eddy currents are generated inside the gold electrode by the faraday effect. Under the action of an external magnetic field, ampere force is generated to act on the piezoelectric phase, so that voltage is generated.

Referring to fig. 2, the principle of the PVDF piezoelectric film sample under the action of the ac magnetic field provided by the embodiment of the invention is as follows: when the voltage amplifier 8 is controlled by the waveform generator 9, and an alternating current magnetic field emitted by the Helmholtz coil 2 is set to penetrate through the PVDF piezoelectric film laminated structure 1, eddy current is generated in the metal electrode through the Faraday effect, and under the action of a direct current bias magnetic field, ampere force acts on a piezoelectric phase to generate magnetoelectric conversion output voltage.

Referring to fig. 3, a general diagram of a test experiment platform for the generalized magnetoelectric effect energy conversion method provided by the embodiment of the present invention is shown. A cantilever beam-based generalized magnetoelectric effect energy conversion method comprises the following steps:

step 1, fixing one end of a PVDF piezoelectric film 1, fixing the PVDF piezoelectric film to the middle part of two electrodes of a Helmholtz coil 2 and an electromagnet 3 by using a sample clamp 5 in a cantilever beam structure, and enabling the directions of an alternating current magnetic field and a direct current magnetic field to be vertical to each other;

and 2, controlling a voltage amplifier 8 through a waveform generator 9, and setting the alternating current magnetic field emitted by the Helmholtz coil 2 to be 5oe and 1000 Hz. The magnetic field generated by the dc magnetic field generator 3 connected to the dc voltage source 10 is-2500 Oe to 2500 Oe. Measuring a magnetic field value through a Hall probe 6 connected with a Tesla meter 7, measuring piezoelectric current induced by the magnetic field by using a current amplifier and a phase-locked amplifier at room temperature to obtain current response, and obtaining the relation between the output voltage of the PVDF sample and a direct-current magnetic field;

step 3, setting the magnetic field generated by the direct current magnetic field generator 3 to be 1000oe, setting the alternating current magnetic field to be 5oe, changing the frequency from 10Hz to 1470Hz, and obtaining current response by using a current amplifier and a phase-locked amplifier to obtain the relation between the output voltage of the PVDF sample and the frequency of the alternating current magnetic field;

and 4, testing the vibration parameters of the PVDF piezoelectric film by using a laser vibrometer system consisting of a sensor (OFV-505Polytec.France) and a laser controller (OFV-5000Polytec.France) to verify that the researched electromagnetic effect is an electromagnetic coupling phenomenon through mechanical coupling interaction.

Referring to fig. 4 and 5, graphs of the PVDF sample output voltage versus the dc magnetic field and the ac magnetic field frequency are shown, respectively. FIG. 4 is a graph of experimental measurement results of the electromagnetic voltage in the range of-0.25T to 0.25T of the DC magnetic field. The graph shows that the larger the Lorentz force and the bending degree induced by the PVDF film sample along with the increase of the applied direct current magnetic field, the larger the magnetoelectric voltage is. FIG. 5 is a graph of experimental measurements of magnetoelectric voltage over a range of AC field frequencies from 10Hz to 1470 Hz. It is shown that, with the increase of the frequency of the alternating magnetic field, the stronger the magnetic field intensity passing through the surface of the metal, the larger the induced current generated, and the larger the output voltage of the PVDF piezoelectric material. Due to the influence of frequency fluctuation, the output voltage has a fluctuation rising trend. When the ac frequency is less than 1kHz, the output voltage increases faster with increasing frequency, and when the ac frequency is greater than 1kHz, the output voltage increases slower with increasing frequency.