A dielectric constant test system and test method based on charge amplifier

Abstract

A kind of dielectric constant test system and test method based on charge amplifier belong to dielectric constant test technical field.To realize accurate broadband dielectric coefficient test function, the present application includes test sample, first clamp, table body, second clamp is placed in stainless steel tank, test sample is placed on table body, and table body is the platform of silver-coated acrylic plate top surface;First clamp is in close contact with the upper surface of test sample, and second clamp is in close contact with the top surface of table body;One end of test signal generator is connected with first clamp, the other end of test signal generator is connected with preamplifier, preamplifier is connected with band-pass filter, band-pass filter is connected with reference signal generator and multiplier respectively, multiplier is connected with low-pass filter, low-pass filter is connected with output amplifier, output amplifier is connected with charge amplifier, charge amplifier is connected with second clamp, and charge amplifier is connected with signal detector in parallel.The present application improves test efficiency.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of dielectric constant test, and particularly relates to a dielectric constant test system and method based on a charge amplifier. BACKGROUND

[0002] The test method of dielectric materials is an important means to study the electrical properties of materials, mainly by measuring the dielectric constant, dielectric loss and other key parameters of the material, reflecting the behavior of the material in the electric field, helping to evaluate its applicability in electrical and electronic equipment. In recent years, with the rapid development of dielectric ceramics in electronic, communication, energy, audio, biotechnology and many other high-tech fields, especially the dielectric constant, which represents the ability of the material to store electrical energy, under the background of the rapid development of new energy vehicles, the demand for high-energy storage batteries is increasing, and higher requirements are put forward for high-dielectric constant materials. Therefore, more efficient and more accurate dielectric testing is required to provide reliable basic data for material development and engineering application.

[0003] The current main method for measuring dielectric constant is the bridge method, which is realized through an impedance analyzer. The working principle is to measure the impedance through the balanced bridge method. In the balanced state, the measured impedance is equal to the known impedance of the bridge, so that the value of the measured impedance can be accurately calculated. The bridge uses the measured amplitude and phase information to realize accurate impedance calculation through the relationship between the output voltage and current. In addition, the digital bridge method also has an automatic balancing mechanism. The bridge will provide an AC signal (usually a sine wave) with a known frequency and amplitude to excite the object to be measured. The comparator measures the phase difference between the bridge output voltage and current, and judges whether the bridge is balanced. If it is not balanced, the control element will automatically adjust the internal digital potentiometer, DAC, etc., so as to adjust the size of the known impedance, so that the bridge reaches the balanced state. However, there is a problem that the measurement frequency range is narrow, and the accuracy of the device will be greatly reduced when measuring the dielectric constant at a lower frequency. SUMMARY

[0004] The problem to be solved by the present application is to realize precise wideband dielectric coefficient test function, and a dielectric constant test system and method based on a charge amplifier are provided.

[0005] To achieve the above purpose, the technical scheme of the present application is as follows:

[0006] A dielectric constant test system based on a charge amplifier, comprising a test signal generator, a reference signal generator, a preamplifier, a bandpass filter, a multiplier, a low-pass filter, an output amplifier, a charge amplifier, a signal detector, a test sample, a first clamp, a stainless steel tank, a table body and a second clamp.

[0007] The test sample, the first clamp, the table body and the second clamp are placed in a stainless steel tank, the test sample is placed on the table body, and the table body is a silver-coated acrylic plate platform;

[0008] The first clamp is in close contact with the upper surface of the test sample, and the second clamp is in close contact with the top surface of the table body.

[0009] One end of the test signal generator is connected to the first clamp, the other end of the test signal generator is connected to the preamplifier, the preamplifier is connected to the band-pass filter, the band-pass filter is connected to the reference signal generator and the multiplier respectively, the multiplier is connected to the low-pass filter, the low-pass filter is connected to the output amplifier, the output amplifier is connected to the charge amplifier, the charge amplifier is connected to the second clamp, and the charge amplifier is connected to the signal detector in parallel.

[0010] Further, the first clamp and the second clamp are both steel spring structures.

[0011] Further, the connection mode adopts wire connection, and the wires are connected by BNC wires.

[0012] A dielectric constant test method based on a charge amplifier, relying on the dielectric constant test system based on the charge amplifier to realize, comprising the following steps:

[0013] S1. Connect the dielectric constant test system based on the charge amplifier with BNC wires.

[0014] S2. Set the sensor sensitivity T and the scale factor S on the charge amplifier, and the parameter range is as follows:

[0015] T is set to 8.5·10 -9 ~ 9.1·10 -9 C / Mechanical_unit, and S is set to 9.5~10.5 Mechanical_unit / V.

[0016] S3. Set the amplitude of the reference signal generator to U.

[0017] S4. Set the excitation frequency of the reference signal generator, then select the time constant of the signal detector, and then measure the voltage of the charge amplifier as U 测 ;

[0018] S5. Adjust the excitation frequency of the reference signal generator to repeat step S4, then calculate the equivalent capacitance C p of the test sample according to the calculation formula, and then calculate the dielectric constant ε r of the test sample, and the calculation formula is as follows:

[0019]

[0020] Wherein, d is the thickness of the test sample, ε0 is the vacuum dielectric constant, and s is the surface area of the test sample.

[0021] Further, the range of the amplitude of the reference signal generator in step S3 is 0.995-1.005V.

[0022] Further, the adjustment range of the excitation frequency of the reference signal generator in step S5 is 10Hz-102.4kHz.

[0023] Further, the length of the BNC wire is 0.25-1.00m.

[0024] The beneficial effects of the present application are:

[0025] The dielectric constant test system based on the charge amplifier has the functions of precise wideband dielectric coefficient test and low cost, can realize wideband dielectric loss angle and voltage test functions, can calculate the dielectric coefficient of the sample in combination with the calculation formula, greatly improves the test efficiency, and accelerates the research and application process of dielectric and derived materials. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 Fig. 1 is a structural schematic diagram of the dielectric constant test system based on the charge amplifier;

[0027] Figure 2 Fig. 2 is a schematic diagram of the connection between the clamp and the test sample;

[0028] Figure 3 Fig. 3 is a comparison diagram of test effects under high frequency;

[0029] Figure 4 Fig. 4 is a comparison diagram of test effects under low frequency. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical scheme and advantages of the present application clearer, the present application is further described in detail below in combination with the drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application, that is, the described specific embodiments are only a part of the embodiments of the present application, but not all the specific embodiments. The components of the specific embodiments of the present application described and shown in the drawings herein can be arranged and designed in various different configurations, and the present application can also have other embodiments.

[0031] Therefore, the following detailed description of the specific embodiments of the application provided in the drawings is not intended to limit the scope of the claimed application, but merely represents selected specific embodiments of the application. Based on the specific embodiments of the application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of the protection of the application.

[0032] In order to further understand the invention content, characteristics and effects of the application, the following specific embodiments are exemplified, and the accompanying drawings are provided Figure 1 -Appendix Figure 4 The detailed description is as follows:

[0033] Example 1

[0034] A dielectric constant test system based on a charge amplifier, comprising a test signal generator 1, a reference signal generator 2, a preamplifier 3, a band-pass filter 4, a multiplier 5, a low-pass filter 6, an output amplifier 7, a charge amplifier 8, a signal detector 9, a test sample 10, a first clamp 11, a stainless steel tank 12, a table body 13, a second clamp 14;

[0035] The test sample 10, the first clamp 11, the table body 13, and the second clamp 14 are placed in the stainless steel tank 12, the test sample 10 is placed on the table body 13, and the table body 13 is a platform of an acrylic plate with a silver top surface;

[0036] The first clamp 11 tightly contacts the upper surface of the test sample 10, and the second clamp 14 tightly contacts the top surface of the table body 13, and then connects the lower surface of the test sample 10 through the top surface of the table body 13;

[0037] One end of the test signal generator 1 is connected to the first clamp 11, the other end of the test signal generator 1 is connected to the preamplifier 3, the preamplifier 3 is connected to the band-pass filter 4, the band-pass filter 4 is respectively connected to the reference signal generator 2 and the multiplier 5, the multiplier 5 is connected to the low-pass filter 6, the low-pass filter 6 is connected to the output amplifier 7, the output amplifier 7 is connected to the charge amplifier 8, the charge amplifier 8 is connected to the second clamp 14, and the charge amplifier 8 is connected in parallel with the signal detector 9.

[0038] Further, the first clamp 11 and the second clamp 14 are both steel spring structures.

[0039] Further, the connection mode adopts wire connection, and the wires are all connected by BNC wires.

[0040] Further, the technical parameters of the test signal generator 1 are that a positive sine wave can be generated, the adjustment frequency range is set to 10Hz-102.4KHz, and the output amplitude range is 0.01V-5.00V;

[0041] Further, the technical parameters of the reference signal generator 2 are to generate a sine wave, and the adjustment frequency range is set to 10 Hz-102.4 KHz, and the output amplitude range is 0.01 V-5.00 V;

[0042] Further, the model of the preamplifier 3 is OPA627AM;

[0043] Further, the technical parameters of the band-pass filter 4 are that the dynamic reserve is >100 dB;

[0044] Further, the model of the multiplier 5 is AD630AD;

[0045] Further, the model of the low-pass filter 6 is NE5532AI;

[0046] Further, the technical parameters of the output amplifier 7 are that the amplification multiple is 1-1000 times, and the gain accuracy is ±1%;

[0047] Further, the model of the charge amplifier 8 is KISTLER Type 5011;

[0048] Further, the model of the signal detector 9 is SDS1000X-E.

[0049] The noise reduction principle of the dielectric constant test system based on the charge amplifier according to the embodiment is as follows:

[0050] In the circuit, the output signal of the to-be-measured signal generator can be defined as:

[0051]

[0052] wherein S1(t) is the to-be-measured alternating current signal, the amplitude is U1, the angular frequency is ω, and the phase is B is the total noise, which is very weak compared with U1; the main principle is to provide an excitation frequency to excite the to-be-measured sample, the sample generates corresponding signal characteristics, and then the to-be-measured signal generator outputs; the reference signal generator generates a reference alternating current signal, which is defined as follows:

[0053] The sine two-way reference signal is:

[0054]

[0055] Firstly, the to-be-measured signal and the reference signal S R enter the low-pass filter, the to-be-measured signal is filtered by means of the reference signal, and then after passing through the output amplifier, the following can be obtained:

[0056]

[0057] wherein U R is the reference signal amplitude;

[0058] Since the amplitude of the reference signal can be adjusted, for the sake of simplicity, we select the same value as the amplitude of the signal to be measured, and then the amplitude R of the signal to be measured and the phase

[0059]

[0060]

[0061] wherein δ is the dielectric loss angle; the dielectric material to be measured can be equivalent to a capacitor C p and a resistor R p in parallel, and by means of the above two measured parameters, the relative dielectric constant ε r and the dielectric loss tan δ can be obtained, and their relationship is:

[0062]

[0063] wherein d is the thickness of the material to be measured, s is the effective area of the material, and ε0 is the dielectric constant of vacuum;

[0064] In the circuit, the signal generator applies a voltage in the circuit, which passes through the filter and is finally represented as U, so that the charge amplifier and the material to be measured are subjected to the measured voltage U 测 and the voltage U p , wherein since the resistance of the charge amplifier is much smaller than that of the sample to be measured, U p can be approximated as the initial voltage U set by the signal generator (in the experiment, it is set to 0.995-1.005 V). By means of the sensor sensitivity T and the scale factor S set by the charge amplifier, and the measured voltage U 测 , the charge at both ends of the sample to be measured can be calculated, and then the voltage U p at both ends thereof is obtained, and the capacitance thereof is further calculated.

[0065] The time constant of the signal detector and the excitation frequency f of the reference signal generator are set, wherein the time constant determines the detection frequency of the signal detector, and the shorter the time, the faster the measurement speed, but since less data is selected, the error will be larger. Usually, the time constant is set to 6πf-20πf. Often, the dielectric constant of the sample to be measured is not consistent at different excitation frequencies, so it is necessary to excite the sample one by one from low frequency to higher frequency (usually from 10 Hz to 100 kHz) to fully understand the dielectric properties of the sample.

[0066] Due to the phase transition in the circuit, the dielectric loss angle δ is actually:

[0067]

[0068] Embodiment 2

[0069] A dielectric constant test method based on a charge amplifier, which is implemented by the dielectric constant test system based on a charge amplifier described in Embodiment 1, comprises the following steps:

[0070] S1. Connect the dielectric constant test system based on a charge amplifier by using a BNC line;

[0071] S2. Set the sensor sensitivity T and the scale factor S on the charge amplifier, and the parameter range is as follows:

[0072] T is set to 8.5·10 -9 ~ 9.1·10 -9 C / Mechanical_unit, and S is set to 9.5~10.5 Mechanical_unit / V;

[0073] S3. Set the amplitude of the reference signal generator to U;

[0074] Further, the amplitude of the reference signal generator in step S3 is set to 0.995V~1.005V.

[0075] S4. Set the excitation frequency of the reference signal generator, then select the time constant of the signal detector, and then measure the voltage of the charge amplifier as U 测 ;

[0076] S5. Adjust the excitation frequency of the reference signal generator to repeat step S4, then calculate the equivalent capacitance C of the test sample according to the calculation formula p , then calculate the dielectric constant ε of the test sample r , and the calculation formula is as follows:

[0077]

[0078] Wherein, d is the thickness of the test sample, ε0 is the vacuum dielectric constant, and s is the surface area of the test sample.

[0079] Further, the adjustment range of the excitation frequency of the reference signal generator in step S5 is 10Hz~102.4kHz.

[0080] Further, the length of the BNC line is 0.25m~1.00m.

[0081] The specific implementation effects of this embodiment are as follows:

[0082] Take the thickness d = 0.22mm, radius r = 5.00mm size sapphire as the experimental object, in the experiment, the parameters of the charge amplifier are set as follows:

[0083] T = 9 10 -9 C / Mechanical_unit, S = 10Mechanial_unit / V;

[0084] By testing different excitation frequencies of the same sample, the charge amplifier method and the bridge method are compared, wherein the bridge method uses the same TH2838 impedance tester. The experimental data comparison is shown in Figure 3 , Figure 3 The middle ordinate represents the dielectric constant ε r It can be seen that the accuracy of the charge amplifier method is basically the same as that of the bridge method, proving the reliability of the charge amplifier method.

[0085] The test results at low frequency are shown in Figure 4 It can be seen that the results obtained by the bridge method have a large deviation, and the minimum test frequency of the bridge method is 20Hz, while the charge amplifier method can measure the dielectric parameters at lower frequencies. It can be seen that the performance of the charge amplifier method is better at low frequency.

[0086] It should be noted that the relational terms, such as "first" and "second", and the like, are used only to distinguish one entity or action from another, and do not necessarily require or imply any actual relationship or order between or among such entities or actions. Moreover, the terms "comprises", "comprising", or any other variant thereof are intended to cover non-exclusive inclusions, so that a process, method, article, or apparatus that comprises a list of elements does not only include those elements, but also includes other elements not expressly listed, or other elements inherent in such process, method, article, or apparatus. Without more limitations, the element defined by the statement "comprises a" does not exclude the presence of additional identical elements in the process, method, article, or apparatus that includes the element.

[0087] Although the present application has been described above with reference to specific embodiments, various modifications can be made without departing from the scope of the present application, and equivalent components can be substituted therefor. In particular, each feature in the specific embodiments disclosed in the present application can be combined with any other feature in any manner, provided that there is no structural conflict. The combinations of these features are not exhaustively described in the present specification, which is merely for the purpose of omitting the description and saving resources. Therefore, the present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A dielectric constant test system based on a charge amplifier, characterized in that: The device comprises a test signal generator (1), a reference signal generator (2), a preamplifier (3), a bandpass filter (4), a multiplier (5), a low-pass filter (6), an output amplifier (7), a charge amplifier (8), a signal detector (9), a test sample (10), a first fixture (11), a stainless steel tank (12), a platform (13), and a second fixture (14); The test sample (10), the first fixture (11), the platform (13), and the second fixture (14) are placed in a stainless steel tank (12), and the test sample (10) is placed on the platform (13), and the platform (13) is an acrylic plate platform with a silver-coated top surface; The first clamp (11) is in close contact with the upper surface of the test sample (10), and the second clamp (14) is in close contact with the bottom surface of the platform (13); One end of the test signal generator (1) is connected to a first fixture (11), and the other end of the test signal generator (1) is connected to a preamplifier (3), the preamplifier (3) is connected to a bandpass filter (4), the bandpass filter (4) is respectively connected to a reference signal generator (2) and a multiplier (5), the multiplier (5) is connected to a low-pass filter (6), the low-pass filter (6) is connected to an output amplifier (7), the output amplifier (7) is connected to a charge amplifier (8), the charge amplifier (8) is connected to a second fixture (14), and the charge amplifier (8) is connected in parallel to a signal detector (9).

2. The dielectric constant testing system based on a charge amplifier according to claim 1, characterized in that: The first clamp (11) and the second clamp (14) are both steel spring structures.

3. The dielectric constant testing system based on a charge amplifier according to claim 1, characterized in that: The connection method adopts wire connection, and the wires are all connected using BNC lines.

4. A dielectric constant test method based on a charge amplifier, implemented by a dielectric constant test system based on a charge amplifier according to any one of claims 1 to 3, characterized in that: The steps include: S1. Connect the charge amplifier-based dielectric constant measurement system described above using a BNC cable; S2. Set the sensor sensitivity T and scale factor S on the charge amplifier. The setting parameters range are as follows: T is set to 8.5·10 -9 ~9.1·10 -9 C / Mechanical_unit, S is set to 9.5~10.5Mechanical_unit / V; S3. Set the amplitude of the reference signal generator to U; S4. Set the excitation frequency of the reference signal generator, select the time constant of the signal detector, and then measure the voltage of the charge amplifier as U 测 ; S5. Adjust the excitation frequency of the reference signal generator and repeat step S4, then calculate the equivalent capacitance C of the test sample according to the calculation formula p , and then calculate the dielectric constant ε of the test sample r , the calculation formula is as follows: Where d is the thickness of the test sample, ε0 is the vacuum dielectric constant, and s is the surface area of ​​the test sample.

5. The dielectric constant testing method based on a charge amplifier according to claim 4, characterized in that: In step S3, the amplitude of the reference signal generator is set to a range of 0.995V to 1.005V.

6. The dielectric constant testing method based on a charge amplifier according to claim 5, characterized in that: The adjustment range of the excitation frequency of the reference signal generator in step S5 is 10 Hz to 102.4 kHz.

7. The dielectric constant testing method based on a charge amplifier according to claim 6, characterized in that: The length of the BNC line is 0.25m to 1.00m.

Images