Self-adapting circuit design method and device for piezoelectric shunt sheet

Abstract

An adaptive circuit design method and apparatus for a piezoelectric shunt plate includes the following steps: constructing a simulation model of the piezoelectric shunt plate and plotting the initial sound insulation curve of the piezoelectric shunt plate without a shunt circuit; fitting the initial sound insulation curve to obtain an ideal correlation curve between the elastic modulus and frequency, and adjusting the parameters of the ideal correlation curve to obtain a target elastic modulus; for the piezoelectric shunt plate connected to the shunt circuit, dynamically adjusting the impedance value of the shunt circuit and calculating the equivalent elastic modulus of the piezoelectric elements in the piezoelectric shunt plate, determining the impedance value corresponding to the equivalent elastic modulus matching the target elastic modulus as the target impedance; and using the shunt circuit corresponding to the target impedance as the target shunt circuit. This invention achieves effective isolation of low-frequency broadband noise by controlling the equivalent modulus of the piezoelectric elements through the shunt circuit.

Description

Technical Field

[0001] This invention relates to the field of low-frequency broadband sound insulation, and in particular to an adaptive circuit design method and apparatus for a piezoelectric shunt thin plate. Background Technology

[0002] With increasing societal emphasis on environmental protection and human health, noise control technology has become crucial in the development of my country's equipment manufacturing industry. Especially in the face of fierce international market competition, effectively controlling noise, particularly low-frequency noise, has become a critical technical challenge that urgently needs to be addressed. Low-frequency noise is characterized by its high energy, long propagation distance, and distinctive spectral features, significantly impacting the quality of the acoustic environment. However, traditional sound insulation technologies have significant limitations in dealing with low-frequency noise; they are often more suitable for blocking high-frequency noise, while their effectiveness in suppressing low-frequency noise is poor. This powerful penetrating force of low-frequency noise makes it an undeniable factor in environmental pollution.

[0003] In the application of sound insulation materials, the performance of thin-plate materials in low-frequency sound insulation is limited by the law of mass density. According to this law, to improve the sound insulation effect, the mass of the material needs to be increased several times over. For example, doubling the mass only improves the sound insulation effect by 6 decibels. This direct proportionality between mass and sound insulation effect limits the application potential of thin-plate materials in low-frequency noise control and also highlights the technical challenges in improving their low-frequency sound insulation performance. Summary of the Invention

[0004] The main objective of this invention is to overcome the problem of low-frequency broadband sound insulation in the field of noise control. It proposes an adaptive circuit design method and device for a piezoelectric shunt thin plate, which adjusts the equivalent modulus of the piezoelectric sheet through the shunt circuit to achieve effective isolation of low-frequency broadband noise.

[0005] The present invention adopts the following technical solution:

[0006] An adaptive circuit design method for a piezoelectric shunt thin plate includes the following:

[0007] A simulation model of the piezoelectric shunt plate was constructed, and the initial sound insulation curve of the piezoelectric shunt plate without the shunt circuit was plotted.

[0008] The initial sound insulation curve is fitted to obtain an ideal correlation curve between the elastic modulus and frequency. The parameters of the ideal correlation curve are then adjusted to obtain the target elastic modulus.

[0009] For the piezoelectric shunt plate connected to the shunt circuit, the impedance value of the shunt circuit is dynamically adjusted and the equivalent elastic modulus of the piezoelectric sheet in the piezoelectric shunt plate is calculated respectively. The impedance value corresponding to the equivalent elastic modulus that matches the target elastic modulus is determined as the target impedance.

[0010] The shunt circuit corresponding to the target impedance is called the target shunt circuit.

[0011] A simulation model of the piezoelectric shunt plate was built using finite element simulation software. The model includes a substrate, a first piezoelectric sheet group, and a second piezoelectric sheet group. The first piezoelectric sheet group includes several piezoelectric sheets arranged in an array and fixed on the front side of the substrate. The second piezoelectric sheet group includes several piezoelectric sheets arranged in an array and fixed on the back side of the substrate. The piezoelectric sheets in the first and second piezoelectric sheet groups are arranged in a one-to-one correspondence and symmetrically relative to the substrate. For the piezoelectric shunt plate connected to the shunt circuit, each piezoelectric sheet is connected to a shunt circuit.

[0012] The initial sound insulation curve of the thin-plate device without the shunt circuit is plotted as follows:

[0013] The simulation model of the piezoelectric shunt plate also includes an air domain, with a plane wave radiation incident pressure field applied at the bottom of the air domain to simulate the vertical incidence of sound waves; and a plane wave absorbing boundary set at the top of the air domain to simulate the transmission or reflection behavior of sound waves.

[0014] A first integration plane is set between the bottom of the air domain and the piezoelectric sheet of the second piezoelectric sheet group to calculate the incident sound energy W. in A second integration plane is set between the top of the air domain and the piezoelectric sheets of the first piezoelectric sheet group to calculate the transmitted sound energy W. out ;

[0015] Based on the acoustic energy integral results, the transmission loss STL at each frequency is calculated using the following formula:

[0016] STL = 10log(W) in / W out );

[0017]

[0018] P in P represents the incident sound pressure. out The transmitted sound pressure is ρ; intop1 and intop2 are integral operators in the simulation software, where ρ and c represent the density of air and the speed of sound, respectively.

[0019] The sound transmission loss curve of the piezoelectric element in a set frequency range when no shunt circuit is connected is then obtained as the initial sound insulation curve.

[0020] Based on the influence of the elastic modulus of the piezoelectric element on the sound transmission loss of the piezoelectric shunt plate, an ideal correlation curve is obtained by fitting the peak data of the initial sound insulation curve using a mathematical function.

[0021] The mathematical function used includes polynomials, exponential functions, power functions, or piecewise functions.

[0022] The equivalent elastic modulus of the piezoelectric element in the piezoelectric shunt plate is calculated as follows:

[0023]

[0024] Where s=iω is the Laplace constant, representing a complex variable in the frequency domain; Z is the impedance value of the shunt circuit; C is the compliance coefficient under constant electric field conditions. p The inherent capacitance of the piezoelectric element; A s h is the area of ​​the piezoelectric electrode. p The thickness of the piezoelectric element; It is the piezoelectric stress constant.

[0025] The connected shunt circuit is a synthesized impedance circuit, including a power operational amplifier, a differential operational amplifier, and a digital signal processor. The negative input and output terminals of the power operational amplifier are connected to the two ends of the piezoelectric element. The positive input terminal of the differential operational amplifier is connected to the output terminal of the power operational amplifier, and the negative input terminal of the differential operational amplifier is connected to the negative input terminal of the power operational amplifier. The input terminal of the digital signal processor is connected to the output terminal of the differential operational amplifier, and the output terminal is connected to the positive input terminal of the power operational amplifier through an amplifier. The impedance value is calculated and adjusted in real time using a preset admittance function Y(s) of the digital signal processor D.

[0026]

[0027] The admittance function Y(s) has the following form:

[0028]

[0029] Where s=iω is the Laplace constant; R is the internal resistance of the synthesized impedance circuit; and L and C represent the equivalent inductance and equivalent capacitance of the synthesized impedance circuit, respectively.

[0030] The connected shunt circuit is a controlled voltage source synthesized impedance circuit, including a negative feedback circuit, its inductor, and a microcontroller unit. The negative feedback circuit and its inductor serve as an equivalent negative inductor. Through the virtual short and virtual open characteristics of the operational amplifier in the negative feedback circuit, the equivalent impedance and equivalent inductance of the negative inductor are obtained.

[0031] The microcontroller unit, acting as an equivalent negative capacitor, includes a reference capacitor, an input amplifier, an output amplifier, and a microcontroller. The input amplifier and output amplifier are respectively connected to the input and output terminals of the microcontroller's built-in analog-to-digital converter and digital-to-analog converter. The input amplifier, the output amplifier, and the microcontroller form a voltage source. The input terminal of the voltage source is connected to one end of the reference capacitor, and the other end of the reference capacitor is connected to the output terminal of the voltage source. The input voltage u0 of the voltage source and the output voltage e of the voltage source are... c The relationship between them is:

[0032]

[0033] Among them, C and q c These are the capacitance and charge on the reference capacitor, respectively.

[0034] A piezoelectric shunt sound insulation thin plate device based on variable equivalent modulus includes a substrate, a first piezoelectric sheet group, and a second piezoelectric sheet group. The first piezoelectric sheet group includes a plurality of piezoelectric sheets arranged in an array and fixed on the front side of the substrate, and the second piezoelectric sheet group includes a plurality of piezoelectric sheets arranged in an array and fixed on the back side of the substrate. The piezoelectric sheets in the first and second piezoelectric sheet groups are arranged in a one-to-one correspondence and symmetrically relative to the substrate. Each piezoelectric sheet is connected to a shunt circuit, and the shunt circuit adopts the target shunt circuit determined by the adaptive circuit design method of the piezoelectric shunt thin plate.

[0035] As can be seen from the above description of the present invention, compared with the prior art, the present invention has the following beneficial effects:

[0036] In this invention, by establishing a constraint mechanism based on the correlation curve between elastic modulus and frequency, and combining dynamic impedance adjustment and numerical inversion techniques, the adaptability optimization of shunt circuit parameters is achieved. Compared to traditional fixed parameter design, this scheme can reverse-engineer circuit parameters according to the target sound insulation requirements, enabling the equivalent elastic modulus of the piezoelectric element to accurately match the preset acoustic characteristic curve, significantly improving the initiative and matching degree of low-frequency sound insulation performance control. Simultaneously, through the collaborative design of simulation models and inversion algorithms, inefficient iterations relying on experience-based trial and error are avoided, providing a lightweight noise control method for thin-plate structures that does not depend on physical structural modifications, and demonstrating universal applicability in impedance matching design of electromechanical coupling systems.

[0037] In this invention, a quantitative characterization of the peak value of the sound insulation curve using mathematical functions is employed to establish an explicit expression of the relationship between elastic modulus and frequency. Compared to empirical parameter matching methods, this fitting method can accurately characterize the intrinsic correlation between the elastic parameters of piezoelectric materials and their sound insulation performance, providing clear design constraints for shunt circuit parameter optimization. Employing a multivariate mathematical adaptation mechanism using polynomials, exponential functions, and other diverse mathematical forms, the optimal fitting model can be selected for different frequency domain acoustic characteristics. This ensures the accuracy of equivalent elastic modulus control while enhancing the adaptability of the design method to the acoustic responses of different materials, effectively supporting the precise control requirements of thin-plate sound insulation structures.

[0038] In this invention, the shunt circuit provides multi-mode impedance implementation methods in specific implementations, including but not limited to traditional LC circuits, microcontroller programmable impedance, and synthesized impedance circuits; through the compatibility design of different circuit forms, it meets the differentiated requirements of impedance matching parameters under different operating conditions. Attached Figure Description

[0039] Figure 1 This is the simulation model of the present invention (including the air domain);

[0040] Figure 2 This is a schematic diagram of the piezoelectric shunt sound insulation thin plate device of the present invention;

[0041] Figure 3 for Figure 1 Side view;

[0042] Figure 4 This is a graph showing the relationship between the elastic modulus of a piezoelectric element and sound transmission loss.

[0043] Figure 5 This is a schematic diagram of the synthesized impedance circuit of the present invention;

[0044] Figure 6 This is a schematic diagram of the controlled voltage source synthesized impedance circuit of the present invention;

[0045] Figure 7 This is a comparison chart of sound transmission loss with and without ideal modulus and shunt circuit.

[0046] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Detailed Implementation

[0047] The present invention will be further described below through specific embodiments.

[0048] The design concept of this invention for low-frequency broadband sound insulation assumes that the piezoelectric element is an ideal material with a constant density. By adjusting its elastic modulus, the change in the sound transmission loss curve is observed. While maintaining a consistent trend in sound insulation performance, the peak sound transmission loss shifts towards the high-frequency region as the elastic modulus increases. Based on this principle, by determining different elastic moduli and their corresponding peak sound transmission losses, an ideal curve relating frequency and elastic modulus is fitted. By connecting a specific shunt circuit to change the equivalent elastic modulus of the piezoelectric element, it is made to approximate the fitted ideal curve, thereby achieving better sound insulation performance in the low-frequency broadband range.

[0049] Based on this, the present invention proposes an adaptive circuit design method for a piezoelectric shunt thin plate, comprising the following:

[0050] S1 builds a simulation model of the piezoelectric shunt thin plate and plots the initial sound insulation curve of the piezoelectric shunt thin plate without the shunt circuit connected.

[0051] In this step, a coupled model, i.e., a simulation model, of the piezoelectric shunt thin plate is built using finite element simulation software. (See [link to relevant documentation]). Figure 1 It includes an air domain, a substrate 1, a first piezoelectric sheet group, and a second piezoelectric sheet group. The first piezoelectric sheet group includes a plurality of piezoelectric sheets 2 arranged in an array and fixed on the front side of the substrate 1. The second piezoelectric sheet group includes a plurality of piezoelectric sheets 2 arranged in an array and fixed on the back side of the substrate 1. The piezoelectric sheets 2 of the first and second piezoelectric sheet groups are arranged in a one-to-one correspondence and symmetrically with respect to the substrate 1. See [link to documentation]. Figure 3 The positions of the piezoelectric sheets 2 on the front and back of the substrate 1 are also one-to-one. In the simulation model, for the piezoelectric shunt plate connected to the shunt circuit 3, each piezoelectric sheet 2 is connected to a shunt circuit 3.

[0052] Furthermore, the initial sound insulation curve of the thin-plate device without the shunt circuit 3 is plotted, specifically as follows:

[0053] First, a plane wave radiation incident pressure field is applied to the bottom 4 (incident plane) of the air domain to simulate the vertical incidence of sound waves. The sound waves are incident upward from the incident plane, pass through the piezoelectric sheet 2 attached to the back of the substrate, and then pass through the substrate 1 and the piezoelectric sheet 2 on the front of the substrate in sequence. A plane wave radiation absorption boundary is set at the top 6 (transmission plane) of the air domain to simulate the transmission or reflection behavior of sound waves.

[0054] Secondly, a first integration plane 3 is set between the bottom 4 of the air domain and the piezoelectric sheet 2 of the second piezoelectric sheet group to calculate the incident sound energy W. in A second integration plane 5 is set between the top 6 of the air domain and the piezoelectric sheet 2 of the first piezoelectric sheet group to calculate the transmitted sound energy W. out ;

[0055] Furthermore, based on the sound energy integration results, the transmission loss STL at each frequency is calculated using the following formula:

[0056] STL = 10log(W) in / W out );

[0057]

[0058] P in P represents the incident sound pressure. out The transmitted sound pressure is ρ; intop1 and intop2 are integral operators in the simulation software, where ρ and c represent the density of air and the speed of sound, respectively.

[0059] Therefore, the sound transmission loss curve of piezoelectric element 2 within a set frequency range when it is not connected to the shunt circuit is obtained as the initial sound insulation curve. For example, see [link to example]. Figure 7 Sound insulation curve (short dashed line) of the thin plate without connected shunt circuit.

[0060] Through the above steps, the sound transmission loss curve of piezoelectric element 2 without the shunt circuit is obtained (e.g., frequency range of 200-1400Hz), with the horizontal axis representing frequency (Hz) and the vertical axis representing sound transmission loss (dB), providing reference data for subsequent circuit optimization.

[0061] S2 fits the initial sound insulation curve to obtain the ideal correlation curve between the elastic modulus and frequency, and adjusts the parameters of the ideal correlation curve to obtain the target elastic modulus.

[0062] Based on the influence of the elastic modulus of piezoelectric element 2 on the sound transmission loss of the piezoelectric shunt plate, the peak data of the initial sound insulation curve are fitted using a mathematical function to obtain the ideal correlation curve.

[0063] Treating piezoelectric element 2 as an ideal homogeneous material, and changing its elastic modulus, a series of graphs showing the relationship between the elastic modulus of piezoelectric element 2 and sound transmission loss were obtained, such as... Figure 4 As shown, the elastic modulus (E, 1-100 GPa) of the piezoelectric element 2 has a significant impact on the sound transmission loss (STL) of the piezoelectric shunt plate. Within the considered frequency range, the sound transmission loss curves corresponding to each elastic modulus all exhibit peak values, and the peak frequency f... peak As the elastic modulus E increases, the STL shifts towards higher frequencies. For example, when E = 1 GPa, the STL reaches 47 dB at 300 Hz; when E = 15 GPa, the peak value of 43 dB is located at 680 Hz; and when E = 30 GPa, the peak value of 42 dB shifts to 740 Hz. The fitting results show that f peak ∝E, verifying the peak frequency f peak There is a positive correlation between it and the material's elastic modulus E, providing a theoretical basis for broadband sound insulation design.

[0064] By analyzing the influence of elastic modulus on the sound insulation performance of thin plates, it was found that as the elastic modulus of piezoelectric sheet 2 increases, the resonance peak of the sound transmission loss curve shifts towards higher frequencies, and the peak frequency corresponding to different elastic moduli is positively correlated with the modulus value. Connecting the peak values ​​of each sound transmission loss can form an envelope that characterizes the upper limit of sound insulation performance. To quantify the correlation between elastic modulus E and frequency f, various mathematical function forms (such as polynomials, exponential functions, power functions, or piecewise functions) are selected according to actual needs to fit the peak data and obtain the ideal correlation curve between elastic modulus and frequency.

[0065] In one embodiment of the present invention, an exponential function is used for exemplary fitting, and the resulting ideal relationship curve expression is as follows:

[0066]

[0067] E ideal Let e ​​be the ideal elastic modulus, f be the natural constant, and k1, k2, k3 be the frequency. All parameters k1, k2, k3 in the formula are constants.

[0068] By adjusting the parameters k1, k2, and k3 in the expression, different ideal elastic moduli can be obtained, from which the target elastic modulus can be determined. For example, by using data analysis software, the values ​​of each parameter in this embodiment can be determined as k1 = 44.974, k2 = 0.0003, and k3 = 0.

[0069] The expression for the elastic modulus of piezoelectric element 2 at different frequencies is preset to E. ideal Its sound insulation effect is as Figure 7 As shown by the solid line, the average sound insulation is 44.6 dB across the entire frequency band (200-1400 Hz).

[0070] S3 For the piezoelectric shunt plate connected to the shunt circuit, dynamically adjust the impedance value of the shunt circuit and calculate the equivalent elastic modulus of the piezoelectric sheet 2 in the piezoelectric shunt plate respectively, and determine the impedance value corresponding to the equivalent elastic modulus that matches the target elastic modulus as the target impedance.

[0071] In this step, after the piezoelectric shunt plate is connected to the shunt circuit, the equivalent elastic modulus of the piezoelectric sheet 2 is calculated synchronously under different impedance values ​​by dynamically adjusting the impedance value of the shunt circuit; the impedance value corresponding to the equivalent elastic modulus that matches the target elastic modulus is determined as the target impedance.

[0072] Treating the piezoelectric element 2 in the piezoelectric shunt plate as a homogeneous elastic material, the equivalent elastic modulus of the piezoelectric element 2 in the piezoelectric shunt plate is calculated as follows:

[0073]

[0074] Where s=iω is the Laplace constant, representing a complex variable in the frequency domain; Z is the impedance value of the shunt circuit; C is the compliance coefficient under constant electric field conditions. p A is the inherent capacitance of piezoelectric element 2; s h is the area of ​​electrode 2 of the piezoelectric element. p The thickness of piezoelectric element 2; It is the piezoelectric stress constant.

[0075] In specific implementations, the shunt circuit of this invention provides multi-mode impedance implementation methods, including but not limited to traditional LC circuits, microcontroller programmable impedance, and synthesized impedance circuits; through the compatibility design of different circuit forms, it meets the differentiated requirements of impedance matching parameters under different operating conditions.

[0076] Taking the connected shunt circuit as an example of a synthesized impedance circuit, it includes a power operational amplifier A1, a differential operational amplifier A2, and a digital signal processor DSP. The negative input and output terminals of the power operational amplifier are connected to the two ends of the piezoelectric element 2. The positive input terminal of the differential operational amplifier is connected to the output terminal of the power operational amplifier, and the negative input terminal of the differential operational amplifier is connected to the negative input terminal of the power operational amplifier. The input terminal of the digital signal processor is connected to the output terminal of the differential operational amplifier, and the output terminal is connected to the positive input terminal of the power operational amplifier through an amplifier. The impedance value is calculated and adjusted in real time by using the preset admittance function Y(s) of the digital signal processor DSP.

[0077]

[0078] The admittance function Y(s) has the following form:

[0079]

[0080] Where s=iω is Laplace's constant; R is the internal resistance of the synthesized impedance circuit; and L and C represent the equivalent inductance and equivalent capacitance of the synthesized impedance circuit, respectively.

[0081] The impedance of the synthesized impedance circuit is determined by the parameters mentioned above. Impedance and admittance function are reciprocals of each other. By determining the parameters in the admittance function Y(s) expression, the impedance value can be determined. The impedance can be indirectly adjusted by adjusting the above parameters.

[0082] For example, a digital signal processor (DSP) can adjust the admittance function Y(s) based on the frequency signal fed back from an acoustic sensor to synthesize an impedance of C = -9.8 × 10⁻⁶. -9 The impedance is F, L = -0.1H.

[0083] Taking the connected shunt circuit as an example of a controlled voltage source synthesized impedance circuit, see [reference needed]. Figure 6It includes a negative feedback circuit and its inductor, and a microcontroller unit. The negative feedback circuit and its inductor serve as an equivalent negative inductor. The negative feedback circuit includes an operational amplifier A5, an operational amplifier A6, a resistor R1, an inductor L1, a resistor R3, and an inductor L2. The positive terminal of the operational amplifier A5 serves as the input terminal, and the input voltage is V. in By utilizing the "virtual short" and "virtual open" characteristics of operational amplifiers, the equivalent impedance Z of the negative inductor can be obtained. eff =-Z L2 ·R2 / R3, their equivalent inductance L eff = -L2·R2 / R3, meaning this part of the circuit as a whole constitutes a negative inductor device, Z L2 Let L1 be the overall impedance of the negative inductor circuit. Using the virtual short and virtual open characteristics of the operational amplifier, this impedance is used as an intermediate variable to calculate the equivalent inductance value of the negative inductor circuit. R1, R2, and R3 are the various resistors on the negative inductor circuit diagram, and L2 is the inductance on the negative inductor circuit diagram. The specific values ​​of the resistors and inductors can be determined by various ratios to determine the equivalent value of the negative inductor circuit.

[0084] The microcontroller unit, acting as an equivalent negative capacitor, includes a reference capacitor C, an input amplifier A3, an output amplifier A4, and a microcontroller. The microcontroller's input and output terminals respectively house an analog-to-digital converter (ADC) and a digital-to-analog converter (DAC). Input amplifier A3 and output amplifier A4 are connected to the ADC and DAC, respectively. Input amplifier A3, output amplifier A4, and the microcontroller together form a voltage source. The input terminal of the voltage source is connected to one end of the reference capacitor C, and the other end of the reference capacitor C is connected to the output terminal of the voltage source. The input voltage u0 and the output voltage e of the voltage source are... c The relationship between them is:

[0085]

[0086] Among them, C and q c These represent the capacitance and charge on the reference capacitor, respectively.

[0087] Specifically, input amplifier A3 measures voltage u0. The measured analog voltage signal is digitized by the ADC and then calculated in real time by the microcontroller. The DAC then converts the output digital signal back into an analog signal and transmits it to output amplifier A4. Output amplifier A4 applies a voltage e to the reference capacitor C. c After being encoded by the microcontroller, it can effectively act as an equivalent negative capacitor. It can also act as a capacitor of any form, thus achieving the desired specific capacitance value C = -9.8 × 10⁻⁹. -9 F. Similarly, the reference impedance Z acts as an inductor, and the desired specific inductance value L = -0.1H can be achieved in a similar way, thereby achieving the desired specific impedance value.

[0088] To achieve the broadband sound insulation effect of the piezoelectric shunt thin plate, the impedance value of the shunt circuit needs to be dynamically adjusted to match its equivalent elastic modulus with the target elastic modulus. The capacitor and inductor parameters were adjusted multiple times in the simulation software to select the values ​​that meet the E... p ≈E ideal The impedance value is taken as the target impedance value.

[0089] The shunt circuit corresponding to the target impedance of S4 is the target shunt circuit.

[0090] For example, simulation tests show that when the capacitance value of the target impedance is C = -9.8 × 10⁻⁶, the result is... -9 When F, inductance L = -0.1H, the sound insulation curve of piezoelectric element 2 connected to the shunt circuit ( Figure 7 (Long dashed line), it can achieve a significant sound insulation effect of an average of 39.6dB in the frequency band below 700Hz; compared with the piezoelectric sheet 2 without the shunt circuit ( Figure 7 The short dashed line (average 23.1dB) shows an average improvement of 16.5dB in sound insulation in the low-frequency range.

[0091] Figure 7 The diagram shows a comparison of sound transmission loss in this embodiment. Compared to the piezoelectric element 2 without a shunt circuit, the piezoelectric element 2 with a shunt circuit exhibits a significant improvement in sound insulation performance within the 200-1400Hz frequency range, especially in the low-frequency region. Its peak sound transmission loss reaches approximately 45dB, and its sound insulation effect in the low-frequency band (200-700Hz) far exceeds that of ordinary piezoelectric elements. This result demonstrates that connecting a shunt circuit and outputting a target impedance has a significant effect on improving the low-frequency sound insulation performance of thin-plate sound insulation structures.

[0092] It should be noted that the equivalent modulus curve obtained through the shunt circuit cannot be matched with the fitted exponential function curve. Figure 7 The solid line indicates that the actual sound transmission loss curve will differ from the predicted result under ideal conditions. This suggests that various factors may lead to performance degradation during the transformation from theoretical models to practical applications, such as material properties, structural defects, and environmental noise. These discrepancies are consistent with basic physical laws.

[0093] This invention also proposes a piezoelectric shunt sound insulation thin plate device based on variable equivalent modulus, see [link to relevant documentation]. Figure 2 and Figure 3The system includes a substrate 1, a first piezoelectric sheet group, and a second piezoelectric sheet group. The first piezoelectric sheet group includes several piezoelectric sheets 2 arranged in an array and fixed on the front side of the substrate 1. The second piezoelectric sheet group includes several piezoelectric sheets 2 arranged in an array and fixed on the back side of the substrate 1. The piezoelectric sheets 2 of the first and second piezoelectric sheet groups are arranged in a one-to-one correspondence and symmetrically relative to the substrate 1. Each piezoelectric sheet 2 is connected to a shunt circuit 3. The shunt circuit 3 adopts the target shunt circuit determined by the above-mentioned adaptive circuit design method of a piezoelectric shunt thin plate.

[0094] In practical applications, substrate 1 can be made of a flat, uniform aluminum plate with excellent mechanical properties. The thickness of the aluminum substrate 1 is 0.15 mm, and the side length is 80 mm. Several piezoelectric sheets 2 are symmetrically attached to both sides of substrate 1. A uniform spacing of 80 mm is maintained between adjacent piezoelectric sheets 2 on the front side and between adjacent piezoelectric sheets 2 on the back side to achieve complete coverage of the substrate 1 surface and ensure a tight bond between the piezoelectric sheets 2 and substrate 1. The piezoelectric sheet 2 has a side length of 40 mm and a thickness of 0.25 mm. The model of the piezoelectric sheet 2 used is PZT-5H. The overall structure is as follows: Figure 3 As shown.

[0095] In this invention, the terms "first," "second," and "third," etc., are used only to distinguish similar objects and are not necessarily used to describe a specific order or sequence, nor should they be construed as indicating or implying relative importance. The use of terms such as "upper," "lower," "left," "right," "front," and "rear" to indicate orientation or positional relationships is based on the orientation or positional relationships shown in the accompanying drawings and is only for the convenience of describing the invention, not to indicate or imply that the device referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation on the scope of protection of this invention. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0096] Furthermore, in the description of this application, unless otherwise stated, "multiple" means two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone. The character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0097] The above are merely specific embodiments of the present invention, but the design concept of the present invention is not limited thereto. Any non-substantial modifications made to the present invention using this concept shall be considered as infringing upon the protection scope of the present invention.

Claims

1. A method of adaptive circuit design for piezoelectric shunt thin plates, characterized by, Including the following: A simulation model of the piezoelectric shunt plate was constructed, and the initial sound insulation curve of the piezoelectric shunt plate without the shunt circuit was plotted. The initial sound insulation curve is fitted to obtain an ideal correlation curve between the elastic modulus and frequency. The parameters of the ideal correlation curve are then adjusted to obtain the target elastic modulus. For the piezoelectric shunt plate connected to the shunt circuit, the impedance value of the shunt circuit is dynamically adjusted and the equivalent elastic modulus of the piezoelectric sheet in the piezoelectric shunt plate is calculated respectively. The impedance value corresponding to the equivalent elastic modulus that matches the target elastic modulus is determined as the target impedance. The shunt circuit corresponding to the target impedance is used as the target shunt circuit; A simulation model of the piezoelectric shunt plate was constructed using finite element simulation software. The model includes a substrate, a first piezoelectric sheet group, and a second piezoelectric sheet group. The first piezoelectric sheet group comprises several piezoelectric sheets arranged in an array and fixed to the front side of the substrate. The second piezoelectric sheet group comprises several piezoelectric sheets arranged in an array and fixed to the back side of the substrate. The piezoelectric sheets in the first and second piezoelectric sheet groups are arranged in a one-to-one correspondence and symmetrically relative to the substrate. For the piezoelectric shunt plate connected to a shunt circuit, each piezoelectric sheet is connected to a shunt circuit. The connected shunt circuit is a synthesized impedance circuit, including a power operational amplifier, a differential operational amplifier, and a digital signal processor. The negative input and output terminals of the power operational amplifier are connected to the two ends of the piezoelectric element. The positive input terminal of the differential operational amplifier is connected to the output terminal of the power operational amplifier, and the negative input terminal of the differential operational amplifier is connected to the negative input terminal of the power operational amplifier. The input terminal of the digital signal processor is connected to the output terminal of the differential operational amplifier, and the output terminal is connected to the positive input terminal of the power operational amplifier through an amplifier. The impedance value is calculated and adjusted in real time using a preset admittance function Y(s) of the digital signal processor D. ； The admittance function Y(s) has the following form: ； wherein is the Laplace constant; R is the internal resistance of the synthetic impedance circuit, L, C represent the equivalent inductance and equivalent capacitance of the synthetic impedance circuit, respectively.

2. A method of designing an adaptive circuit for a piezoelectric shunt thin plate as claimed in claim 1, wherein, The initial sound insulation curve of the thin-plate device without the shunt circuit is plotted as follows: The simulation model of the piezoelectric shunt plate also includes an air domain, with a plane wave radiation incident pressure field applied at the bottom of the air domain to simulate the vertical incidence of sound waves; and a plane wave absorbing boundary set at the top of the air domain to simulate the transmission or reflection behavior of sound waves. A first integration plane is set between the bottom of the air domain and the piezoelectric sheets of the second piezoelectric sheet group to calculate the incident sound energy W. in A second integration plane is set between the top of the air domain and the piezoelectric sheets of the first piezoelectric sheet group to calculate the transmitted sound energy W. out ; Based on the acoustic energy integral results, the transmission loss STL at each frequency is calculated using the following formula: STL = 10 log(W in / W out ); ； ； P in P represents the incident sound pressure. out The transmitted sound pressure; intop1 and intop2 are integral operators in the simulation software, where ρ and c represent the air density and the speed of sound, respectively. The sound transmission loss curve of the piezoelectric element in a set frequency range when no shunt circuit is connected is then obtained as the initial sound insulation curve.

3. The method of claim 1, wherein the piezoelectric shunt thin film is an adaptive circuit design method, characterized by, Based on the influence of the elastic modulus of the piezoelectric element on the sound transmission loss of the piezoelectric shunt plate, an ideal correlation curve is obtained by fitting the peak data of the initial sound insulation curve using a mathematical function.

4. A method of designing a self-adapting circuit for a piezoelectric shunt thin plate as claimed in claim 3, wherein, The mathematical function used includes polynomials, exponential functions, power functions, or piecewise functions.

5. The method of claim 1, wherein the piezoelectric shunt thin film is an adaptive circuit design method, characterized by, The equivalent elastic modulus of the piezoelectric element in the piezoelectric shunt plate is calculated as follows: ； in, It is the Laplace constant, representing a complex variable in the frequency domain; This is the impedance value of the shunt circuit; is the compliance coefficient under constant electric field conditions; This is the inherent capacitance of the piezoelectric element; The area of ​​the piezoelectric electrode; The thickness of the piezoelectric element; It is the piezoelectric stress constant.

6. The method of claim 1, wherein the piezoelectric shunt thin film is an adaptive circuit design method, characterized by, The connected shunt circuit is a controlled voltage source synthesized impedance circuit, including a negative feedback circuit, its inductor, and a microcontroller unit. The negative feedback circuit and its inductor serve as an equivalent negative inductor. Through the virtual short and virtual open characteristics of the operational amplifier in the negative feedback circuit, the equivalent impedance and equivalent inductance of the negative inductor are obtained. The microcontroller unit, acting as an equivalent negative capacitor, includes a reference capacitor, an input amplifier, an output amplifier, and a microcontroller. The input amplifier and output amplifier are respectively connected to the input and output terminals of the microcontroller's built-in analog-to-digital converter and digital-to-analog converter. The input amplifier, the output amplifier, and the microcontroller form a voltage source. The input terminal of the voltage source is connected to one end of the reference capacitor, and the other end of the reference capacitor is connected to the output terminal of the voltage source. The input voltage u0 of the voltage source and the output voltage e of the voltage source are... c The relationship between them is: ； where C and q c are the capacitance and charge on the reference capacitor, respectively.

7. A piezoelectric shunt sound insulation thin plate device based on variable equivalent modulus, comprising a substrate, a first piezoelectric sheet group, and a second piezoelectric sheet group: the first piezoelectric sheet group comprises a plurality of piezoelectric sheets arranged in an array and fixed on the front side of the substrate, the second piezoelectric sheet group comprises a plurality of piezoelectric sheets arranged in an array and fixed on the back side of the substrate, wherein the piezoelectric sheets of the first and second piezoelectric sheet groups are in one-to-one correspondence and symmetrically arranged relative to the substrate; each piezoelectric sheet is connected to a shunt circuit; characterized in that, The shunt circuit adopts the target shunt circuit determined by the adaptive circuit design method of the piezoelectric shunt sheet in any one of claims 1 to 6.

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