A method and related device for sound absorption and noise reduction using a multi-cell coupled hilbert fractal array

Abstract

This invention provides a method and related apparatus for sound absorption and noise reduction using a multi-cell coupled Hilbert fractal array, belonging to the field of high-frequency transformer noise control. The method includes first determining the main frequencies of radiated noise and the target radiating surface parameters based on noise measurement data under rated operating conditions of the high-frequency transformer, and then setting the geometric parameters of individual cells to form a parameter set. Next, through multi-cell array layout design, the geometric parameters of the cells are adjusted so that the resonant center frequencies of each cell form a continuous broadband sound absorption zone covering the target bandwidth, improving the high-frequency noise absorption bandwidth and suppression depth, and effectively suppressing high-frequency noise. Based on this, an array module constructed based on the multi-cell coupled Hilbert array parameters is used for noise reduction. This invention ensures stable long-term noise reduction performance without affecting the transformer's insulation and heat dissipation performance, efficiently and stably suppressing high-frequency noise radiation while balancing the compact structure and high power density of the high-frequency transformer.

Description

Technical Field

[0001] This invention belongs to the field of high-frequency transformer noise control technology, specifically relating to a multi-cell coupled Hilbert fractal array sound absorption and noise reduction method and related device. Background Technology

[0002] High-frequency transformers, as core components of high-voltage, high-capacity DC-DC converters and high-frequency power electronic equipment, are widely used in many fields such as solid-state transformers, photovoltaic inverters, energy storage converters, and high-voltage charging systems for electric vehicles. Their operating status is crucial to the performance and stability of the entire system.

[0003] The core of a high-frequency transformer typically uses an amorphous alloy or nanocrystalline alloy strip winding structure. Under the action of an alternating magnetic field, it will generate a magnetostrictive effect, causing the core to vibrate mechanically and radiate noise. Especially under high-frequency operating conditions of several kilohertz or even tens of kilohertz, the excitation waveform is mostly square wave or rectangular wave, containing a large number of high-order harmonic components. This causes the core and windings to generate multi-mode coupled vibration, forming wide-bandwidth, high-intensity high-frequency noise, which not only affects the operating environment of the equipment but also has adverse effects on human health.

[0004] Currently, noise control for high-frequency transformers mainly employs traditional passive noise reduction techniques, such as structural damping, sound-absorbing encapsulation, and multi-layer composite shells. However, these methods suffer from a significant decrease in absorption coefficient at high frequencies (noise frequencies exceeding 2kHz), failing to effectively suppress high-frequency sharp noise. Furthermore, they are characterized by large structural volume, complex installation, unsuitability for space-constrained high-frequency power supply systems, and unstable long-term noise reduction performance due to material aging, which also affects the transformer's heat dissipation performance. Summary of the Invention

[0005] In view of this, the present invention provides a multi-cell coupled Hilbert fractal array sound absorption and noise reduction method and related device, which aims to effectively suppress the noise radiation of high-frequency transformers while ensuring the compact structure and high power density, improve the absorption bandwidth and suppression depth of high-frequency noise, and at the same time keep the device small in size, easy to integrate, and without affecting the insulation and heat dissipation of the transformer.

[0006] To achieve the above objectives, the technical solution provided by the present invention is as follows:

[0007] In a first aspect, the present invention provides a method for sound absorption and noise reduction using a multi-cell coupled Hilbert fractal array, comprising the following steps:

[0008] Based on the noise measurement data of the high-frequency transformer under rated operating conditions, the main frequency and target radiation surface parameters of the transformer radiated noise are determined.

[0009] Based on the main frequency and target radiation surface parameters, the geometric parameters of a single Hilbert acoustic cell are determined, and the set of Hilbert acoustic cell parameters is obtained based on the geometric parameters.

[0010] The multi-cell array layout is designed based on the Hilbert acoustic cell parameter set to obtain the multi-cell coupled Hilbert array parameters. The multi-cell array layout design involves adjusting the geometric parameters of each cell so that the resonant center frequency of each cell forms a continuous broadband sound absorption zone covering the target wideband range.

[0011] Hilbert array modules are constructed based on multi-cell coupled Hilbert array parameters to suppress high-frequency noise in high-frequency transformers.

[0012] Furthermore, based on noise measurement data of the high-frequency transformer under rated operating conditions, the main frequencies and target radiating surface parameters of the transformer radiated noise are determined, including:

[0013] A hexahedral measuring point arrangement method was used to obtain noise measurement data of high-frequency transformers under rated operating conditions;

[0014] The main frequencies of transformer radiated noise are extracted by performing a Fourier transform on the noise sound pressure in the noise measurement data.

[0015] The surface with the strongest noise is identified as the target radiating surface, and the radiating surface size and available installation area parameters of the target radiating surface are obtained to obtain the target radiating surface parameters.

[0016] Furthermore, the geometric parameters of a single Hilbert acoustic cell are determined, and the set of Hilbert acoustic cell parameters is obtained based on the geometric parameters, including:

[0017] Determine the target equivalent acoustic path of the Hilbert channel based on the primary frequency; the target equivalent acoustic path is set to an odd multiple of one-quarter of the wavelength of the primary frequency.

[0018] Based on the target radiation surface parameters, determine the side length and height of a single Hilbert acoustic cell, and select the order of the Hilbert curve;

[0019] Based on the processing technology and the required thickness of the sound-absorbing layer, the width and thickness of the Hilbert channel were selected.

[0020] Based on the order of the Hilbert curve and the width and thickness of the Hilbert channel, a three-dimensional Hilbert channel model is constructed, and the total path length of the channel centerline of the three-dimensional Hilbert channel model is used as the equivalent sound path approximation.

[0021] Based on the error between the target equivalent sound path and the approximate equivalent sound path, iteratively correct various geometric parameters of a single Hilbert acoustic cell until the error is within the set range;

[0022] By integrating the final Hilbert curve order, the side length and height of a single Hilbert acoustic cell, and the width and thickness of the Hilbert channel, a set of Hilbert acoustic cell parameters is obtained.

[0023] Furthermore, based on the Hilbert acoustic cell parameter set, a multi-cell array layout design is performed to obtain the multi-cell coupled Hilbert array parameters, including:

[0024] For the available installation area of ​​the target radiation surface, a multi-cell array is formed by a preset arrangement;

[0025] Differentiated adjustment of the size and order of each Hilbert acoustic cell in the multi-cell array to stagger the resonant center frequency distribution of each Hilbert acoustic cell;

[0026] Optimize the acoustic input impedance of each Hilbert acoustic cell, determine the absorption characteristics of each Hilbert acoustic cell, and match the corresponding parameters;

[0027] An electrically insulating porous sound-absorbing layer is covered on the channel wall of each Hilbert acoustic cell. The parameters of each Hilbert acoustic cell are integrated and optimized to obtain the parameters of the multi-cell coupled Hilbert array.

[0028] Further optimization of acoustic input impedance and coupling includes:

[0029] Based on the main frequency, determine the function of each Hilbert acoustic cell in the multi-cell array and set the corresponding input impedance target range; the functions include high-Q narrowband resonant absorption and low-Q broadband dissipative absorption.

[0030] Under the constraint of the frontal area of ​​the Hilbert acoustic cell, the geometric parameters of the small hole are initially selected proportionally; the small hole is the connecting hole between the Hilbert acoustic cell and the air cavity inside the transformer housing.

[0031] Adjust the geometric parameters so that the acoustic input impedance of each Hilbert acoustic cell falls within the target range of input impedance;

[0032] By combining the equivalent path length of the Hilbert acoustic cell channel and the flow resistance parameters of the sound-absorbing layer, the resonant frequency and absorption bandwidth of the Hilbert acoustic cell are verified, and the parameters of each Hilbert acoustic cell in the multi-cell array are coordinated until the entire array forms a continuous broadband sound-absorbing zone within the target wideband range.

[0033] Furthermore, after constructing the Hilbert array module based on the parameters of the multi-cell coupled Hilbert array, a noise reduction effect evaluation step is also included, including:

[0034] Install the Hilbert array module in the available mounting area behind the target radiating surface;

[0035] Noise measurement was performed on a high-frequency transformer under rated operating conditions using a hexahedral measuring point arrangement method to obtain the overall radiated sound power level of the transformer after noise reduction.

[0036] For each major frequency corresponding to the target harmonic frequency, the sound pressure reduction before and after noise reduction is calculated based on the overall radiated sound power level of the transformer, and the noise reduction effect is evaluated.

[0037] Secondly, the present invention provides a multi-cell coupled Hilbert fractal array sound absorption and noise reduction device, comprising:

[0038] Multiple Hilbert acoustic cells and rigid substrates;

[0039] Each Hilbert acoustic cell is provided with a channel extending along the Hilbert curve, an electrically insulating porous sound-absorbing layer covering the channel wall, and a small hole communicating with the air cavity inside the high-frequency transformer housing.

[0040] The parameters of each Hilbert acoustic cell are set based on the multi-cell coupled Hilbert array parameters determined by the method described in the first aspect;

[0041] Multiple Hilbert acoustic cells are assembled on a rigid substrate in a preset arrangement to form a Hilbert array module.

[0042] The rigid substrate has a mechanical connection structure for securing the Hilbert array module to the available mounting area behind the target radiating surface of the high-frequency transformer.

[0043] Thirdly, the present invention provides a multi-cell coupled Hilbert fractal array sound absorption and noise reduction system, comprising:

[0044] The noise parameter determination unit is used to determine the main frequency and target radiation surface parameters of the transformer radiated noise based on the noise measurement data of the high-frequency transformer under rated operating conditions.

[0045] The unit cell parameter determination unit is used to determine the geometric parameters of a single Hilbert acoustic cell based on the main frequency and target radiation surface parameters, and to obtain the Hilbert acoustic cell parameter set based on the geometric parameters.

[0046] The multi-cell array parameter design unit is used to design the multi-cell array layout based on the Hilbert acoustic cell parameter set, and obtain the multi-cell coupled Hilbert array parameters. The multi-cell array layout design is to adjust the geometric parameters of each cell so that the resonant center frequency of each cell forms a continuous broadband sound absorption area covering the target wideband range.

[0047] The noise suppression module construction unit is used to construct a Hilbert array module based on the parameters of the multi-cell coupled Hilbert array in order to suppress high-frequency noise in high-frequency transformers.

[0048] Thirdly, the present invention provides a computer device, the device including a processor and a memory:

[0049] The memory is used to store computer programs and send the instructions of the computer programs to the processor;

[0050] The processor executes the following steps according to the instructions of the computer program:

[0051] Based on the noise measurement data of the high-frequency transformer under rated operating conditions, the main frequency and target radiation surface parameters of the transformer radiated noise are determined.

[0052] Based on the main frequency and target radiation surface parameters, the geometric parameters of a single Hilbert acoustic cell are determined, and the set of Hilbert acoustic cell parameters is obtained based on the geometric parameters.

[0053] The multi-cell array layout is designed based on the Hilbert acoustic cell parameter set to obtain the multi-cell coupled Hilbert array parameters. The multi-cell array layout design involves adjusting the geometric parameters of each cell so that the resonant center frequency of each cell forms a continuous broadband sound absorption zone covering the target wideband range.

[0054] Hilbert array modules are constructed based on multi-cell coupled Hilbert array parameters to suppress high-frequency noise in high-frequency transformers.

[0055] Fourthly, the present invention provides a computer-readable storage medium on which a computer program is stored, and when executed by a processor, the computer program performs the following steps:

[0056] Based on the noise measurement data of the high-frequency transformer under rated operating conditions, the main frequency and target radiation surface parameters of the transformer radiated noise are determined.

[0057] Based on the main frequency and target radiation surface parameters, the geometric parameters of a single Hilbert acoustic cell are determined, and the set of Hilbert acoustic cell parameters is obtained based on the geometric parameters.

[0058] The multi-cell array layout is designed based on the Hilbert acoustic cell parameter set to obtain the multi-cell coupled Hilbert array parameters. The multi-cell array layout design involves adjusting the geometric parameters of each cell so that the resonant center frequency of each cell forms a continuous broadband sound absorption zone covering the target wideband range.

[0059] Hilbert array modules are constructed based on multi-cell coupled Hilbert array parameters to suppress high-frequency noise in high-frequency transformers.

[0060] Fifthly, the present invention provides a computer program product, comprising a computer program, characterized in that, when executed by a processor, the computer program performs the following steps:

[0061] Based on the noise measurement data of the high-frequency transformer under rated operating conditions, the main frequency and target radiation surface parameters of the transformer radiated noise are determined.

[0062] Based on the main frequency and target radiation surface parameters, the geometric parameters of a single Hilbert acoustic cell are determined, and the set of Hilbert acoustic cell parameters is obtained based on the geometric parameters.

[0063] The multi-cell array layout is designed based on the Hilbert acoustic cell parameter set to obtain the multi-cell coupled Hilbert array parameters. The multi-cell array layout design involves adjusting the geometric parameters of each cell so that the resonant center frequency of each cell forms a continuous broadband sound absorption zone covering the target wideband range.

[0064] Hilbert array modules are constructed based on multi-cell coupled Hilbert array parameters to suppress high-frequency noise in high-frequency transformers.

[0065] In summary, this invention provides a multi-cell coupled Hilbert fractal array sound absorption and noise reduction method and related apparatus. The method first determines the main frequency of radiated noise and the target radiating surface parameters based on noise measurement data under rated operating conditions of a high-frequency transformer. Then, it sets the geometric parameters of individual Hilbert acoustic cells to form a parameter set, enabling each cell to match the main frequency of the high-frequency noise. Furthermore, through multi-cell array layout design, the geometric parameters of each cell are adjusted so that the resonant center frequency of each cell forms a continuous broadband sound absorption zone covering the target wideband, thereby overcoming the limitations of traditional passive noise reduction technology in the high-frequency range. This significantly improves the absorption bandwidth and suppression depth of high-frequency noise, achieving effective suppression of high-frequency noise. Based on this, the Hilbert array module constructed based on the parameters of the multi-cell coupled Hilbert array, due to its structural characteristics, does not require complex packaging or multi-layer composite shells. It is not only compact and easy to integrate, but also adaptable to space-constrained high-frequency power supply systems. It also avoids the problem of easy aging of traditional noise reduction materials, ensuring stable long-term noise reduction effect. At the same time, its structural design does not affect the insulation performance and heat dissipation effect of the transformer. Ultimately, it achieves both a compact structure and high power density of high-frequency transformers, while efficiently and stably suppressing high-frequency noise radiation. Attached Figure Description

[0066] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0067] Figure 1 A schematic flowchart of a multi-cell coupled Hilbert fractal array sound absorption and noise reduction method provided in an embodiment of the present invention;

[0068] Figure 2 A block diagram of a multi-cell coupled Hilbert fractal array sound absorption and noise reduction system provided in an embodiment of the present invention;

[0069] Figure 3 This is a block diagram of a computer device provided in an embodiment of the present invention. Detailed Implementation

[0070] To make the objectives, features, and advantages of this invention more apparent and understandable, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0071] The background technology of this invention will be described in detail below.

[0072] High-frequency transformers (HFTs), as core components of high-voltage, high-capacity DC-DC converters and high-frequency power electronic equipment, are widely used in solid-state transformers, photovoltaic inverters, energy storage converters, and high-voltage charging systems for electric vehicles. Their cores often employ amorphous alloy or nanocrystalline alloy strip winding structures, which generate magnetostriction under alternating magnetic fields, leading to mechanical vibration and radiating noise. Compared to traditional power frequency transformers, high-capacity HFTs can operate at frequencies of several kilohertz or even tens of kilohertz, with excitation waveforms primarily consisting of square or rectangular waves containing numerous high-order harmonic components. These high-frequency harmonics cause multimodal coupled vibrations in the core and windings, resulting in wide-bandwidth, high-intensity high-frequency noise.

[0073] Under high-frequency operating conditions, vibration can lead to fatigue and localized damage to the core laminations, windings, and insulation components, and may also compromise the stability of the insulation structure. Simultaneously, high-frequency sharp noise, due to its high frequency and short wavelength, possesses strong directivity and high penetrability, easily causing severe noise pollution and adversely affecting the equipment operating environment and human health. Therefore, effectively suppressing the noise radiation of high-frequency transformers while ensuring their compact structure and high power density has become an urgent technical problem to be solved.

[0074] Currently, noise control for high-frequency transformers mainly employs traditional passive noise reduction techniques, including structural damping, sound absorption through encapsulation, and multi-layer composite housings.

[0075] (1) Structural damping method: Set damping film, flexible pad or elastic support structure between iron core and shell to change the transmission path of iron core vibration to shell and reduce solid sound transmission capacity.

[0076] (2) Encapsulation and sound absorption method: attach sound-absorbing cotton, polyurethane foam and other porous sound-absorbing materials to the outer surface of the transformer shell, or set up a soundproof cover so that the airborne sound energy is dissipated in the porous medium and the external sound radiation is reduced;

[0077] (3) Multi-layer composite shell method: Add an air gap layer and a sound-absorbing layer to the outside of the metal plate structure to form an acoustic impedance gradient, so that the sound wave is reflected and attenuated between different interfaces, reducing noise transmission.

[0078] These methods are relatively mature in engineering and widely used in noise suppression of power equipment, but they still have obvious limitations: the sound absorption efficiency drops significantly in the high-frequency range (especially above 2kHz), and cannot effectively suppress high-frequency sharp noise; the external sound-absorbing cover or composite shell is bulky and complicated to install, and is not suitable for high-frequency power systems with compact space; the damping layer or foam material is prone to aging in high-temperature and high-magnetic-flux-density environments, and the long-term noise reduction effect is unstable; the encapsulated structure will also hinder air circulation, increase thermal resistance, and affect the heat dissipation performance of the transformer and the reliability of the system.

[0079] To address the challenge of balancing structural compactness, heat dissipation performance, and high-frequency noise control in existing technologies, this invention proposes a multi-cell coupled Hilbert fractal array sound absorption and noise reduction method and related device. By designing a Hilbert-type fractal acoustic unit array and arranging it inside the transformer housing, ultra-long effective sound path, phase delay, and multi-peak resonance absorption are achieved within a limited space, significantly improving the absorption bandwidth and suppression depth of high-frequency noise. Simultaneously, the device remains small, easily integrated, and does not affect the transformer's insulation and heat dissipation. The various embodiments of this invention are described in detail below.

[0080] In one exemplary embodiment, please refer to Figure 1 This paper provides a method for sound absorption and noise reduction using a multi-cell coupled Hilbert fractal array, comprising the following steps:

[0081] S101: Based on the noise measurement data of the high-frequency transformer under rated operating conditions, determine the main frequency and target radiation surface parameters of the transformer radiated noise.

[0082] Among them, the main noise frequency refers to the set of dominant harmonic frequencies of the noise radiated by the high-frequency transformer under rated operating conditions, which is usually the even harmonic of the fundamental frequency; the target radiation surface parameters refer to the dimensions of the shell surface where the noise radiation is strongest and the internal installation space constraints, which may include the external length and width, internal height, insulation distance requirements and cooling air passage reservation restrictions, etc.

[0083] Optionally, noise data under rated operating conditions of the transformer can be obtained through a standardized noise measurement process. The dominant harmonic frequency can be extracted through frequency domain analysis. At the same time, the target radiation surface with the strongest noise radiation can be located, and the geometric, insulation, and heat dissipation constraint parameters of the available installation area behind it can be measured.

[0084] For example, the high-frequency transformer is placed in a standard test environment, and noise and sound pressure data under rated operating conditions are collected using a standardized measurement point layout method. The main noise frequency set is extracted by Fourier transform, the average sound pressure level of each shell surface is calculated to determine the target radiation surface, and the external dimensions of the target radiation surface and parameters such as the available installation space behind it and the insulation distance are obtained simultaneously.

[0085] S102: Determine the geometric parameters of a single Hilbert acoustic cell based on the main frequency and target radiation surface parameters, and obtain the Hilbert acoustic cell parameter set based on the geometric parameters.

[0086] Among them, the Hilbert acoustic cell geometric parameters may include variables such as the side length a, height H, Hilbert curve order N, channel width b, and channel thickness c; the parameter set refers to the complete set of geometric parameters that meet the target equivalent sound path requirements after iterative correction, and also includes auxiliary design parameters such as the thickness of the sound-absorbing layer.

[0087] Optionally, the equivalent sound path target can be determined based on the target frequency, and the cell shape and Hilbert order can be determined in combination with the installation space constraints. The channel geometric parameters are initially selected and the equivalent sound path is measured by modeling. After iterative correction, the equivalent sound path is made to match the target requirements, and finally integrated to form a standardized set of cell parameters.

[0088] For example, the wavelength and equivalent sound path of the target frequency are calculated. The cell shape and Hilbert order are determined according to the available space of the target radiation surface. The channel width and thickness are initially selected. The actual path length of the channel is measured by simulation modeling. After comparing with the target equivalent sound path, the parameters are iteratively adjusted and finally integrated to obtain a complete set of cell parameters.

[0089] S103: Based on the Hilbert acoustic cell parameter set, a multi-cell array layout design is carried out to obtain the multi-cell coupled Hilbert array parameters; the multi-cell array layout design is to adjust the geometric parameters of each cell so that the resonant center frequency of each cell forms a continuous broadband sound absorption zone covering the target wideband range.

[0090] Among them, the multi-cell array layout refers to arranging multiple Hilbert cells on the target radiation surface in a preset manner to cover the main noise area; the differentiated design refers to achieving staggered distribution of resonant frequencies by fine-tuning cell parameters; the acoustic input impedance is used to control the cell sound absorption characteristics (high Q narrowband / low Q broadband), and finally form the multi-cell coupling array parameters.

[0091] Optionally, the array layout can be designed according to the cell size and target radiation surface parameters, the cells can be differentiated and grouped to broaden the sound absorption bandwidth, the acoustic input impedance can be adjusted by optimizing the aperture parameters of each cell, the sound absorption layer can be configured, and all parameters can be integrated to form an array design scheme.

[0092] For example, the array layout is designed according to the cell size to cover the target radiation surface. The cells are grouped and the parameters are fine-tuned to achieve the staggered distribution of resonant frequencies. The acoustic input impedance of each cell is controlled to fall within the target range by adjusting the geometry parameters of the apertures. An appropriate sound-absorbing layer is configured, and all parameters are integrated to obtain the parameters of the multi-cell coupled Hilbert array.

[0093] S104: Construct a Hilbert array module based on multi-cell coupled Hilbert array parameters to suppress high-frequency noise in high-frequency transformers.

[0094] The Hilbert array module refers to a modular unit formed by multiple cells, which can be assembled on a rigid substrate. The substrate has a mechanical connection structure for fixing to the target radiation surface of the transformer, while meeting the requirements of insulation, heat dissipation and electrical safety.

[0095] For example, Hilbert cells are manufactured using an adaptive process and a sound-absorbing layer is configured. The cells are assembled onto a rigid substrate according to array parameters to form a module. The module is then installed in the neutral potential region behind the target radiating surface to ensure that insulation and heat dissipation requirements are met.

[0096] The method provided in this embodiment enables individual cells to match the main frequencies of high-frequency noise. Through multi-cell array layout design, the geometric parameters of each cell are adjusted so that the resonant center frequencies of each cell form a continuous broadband sound-absorbing zone covering the target wideband. Based on this, a Hilbert array module is constructed based on the parameters of the multi-cell coupled Hilbert array. This module is integrated with a high-frequency transformer through standardized assembly. This overcomes the limitations of traditional passive noise reduction technology in the high-frequency band, significantly improving the absorption bandwidth and suppression depth of high-frequency noise, achieving effective suppression of high-frequency noise. Simultaneously, the Hilbert array module does not require complex packaging or multi-layer composite housings, has a compact structure, is easy to integrate, can adapt to space-constrained high-frequency power systems, and avoids the aging problem of traditional noise reduction materials, ensuring stable long-term noise reduction performance. Its structural design meets the insulation and heat dissipation requirements of transformers, without affecting the insulation performance and heat dissipation effect of the transformer. Ultimately, it achieves both a compact structure and high power density of the high-frequency transformer while efficiently and stably suppressing high-frequency noise radiation.

[0097] In one exemplary embodiment, based on noise measurement data of a high-frequency transformer under rated operating conditions, the main frequency and target radiating surface parameters of the transformer radiated noise are determined, including:

[0098] S201: The noise measurement data of the high-frequency transformer under rated operating conditions is obtained by using a hexahedral measuring point arrangement method.

[0099] The hexahedral measurement point arrangement method refers to arranging microphone measurement points around the six sides of the transformer (front, back, left, right, top, and bottom), conforming to the noise measurement layout of GB / T 3767-2016 standard.

[0100] For example, the transformer can be placed in a semi-anechoic chamber or a near-free sound field environment, and the noise measurement points of the transformer can be arranged using the hexahedral measurement point arrangement method conforming to GB / T 3767-2016. Under rated operating conditions, the noise sound pressure radiated at each measurement point of the transformer can be measured using a microphone.

[0101] S202: Perform Fourier transform on the noise sound pressure in the noise measurement data to extract the main frequencies of the transformer radiated noise.

[0102] Fourier transform refers to a signal processing method that converts time-domain sound pressure signals into frequency-domain spectra, used to extract dominant harmonic frequencies in noise. Dominant frequencies refer to the set of frequency peaks in the spectrum whose sound pressure levels exceed the background noise by more than 10 dB, usually the even harmonics of the transformer's fundamental frequency.

[0103] For example, a Fourier transform is performed on the measured noise sound pressure to obtain the main frequencies of the transformer radiated noise from the spectrum as the target frequency set {f0}.

[0104] S203: Determine the surface with the strongest noise as the target radiation surface, and obtain the radiation surface size and available installation area parameters of the target radiation surface to obtain the target radiation surface parameters.

[0105] Among them, the target radiation surface refers to the shell surface with the highest average sound pressure level at each measuring point, that is, the surface with the strongest noise energy radiation; the available installation area parameters refer to the geometric dimensions and height restrictions of the shell inside behind this surface, as well as the insulation distance from the winding, the reserved cooling air passage, and other constraints.

[0106] For example, the average sound pressure level of each measuring point and the overall sound power level radiated by the transformer are calculated. The surface with the strongest noise is determined as the target radiation surface, and the radiation surface size and available installation area parameters of the target radiation surface are obtained to obtain the target radiation surface parameters.

[0107] This embodiment collects sound pressure data under real operating conditions through a standardized noise measurement process, extracts the dominant harmonic frequency through Fourier transform, calculates and locates the target radiation surface and obtains installation space parameters by calculating the average sound pressure level at the measurement points, ensuring that the subsequent design parameters are highly matched with the actual operating conditions of the transformer, avoiding noise reduction failure caused by parameter deviation, and clarifying the insulation and heat dissipation constraints of the transformer's internal installation.

[0108] In an exemplary embodiment, the geometric parameters of a single Hilbert acoustic cell are determined, and a set of Hilbert acoustic cell parameters is obtained based on the geometric parameters, including:

[0109] S301: Determine the target equivalent sound path of the Hilbert channel based on the primary frequency; the target equivalent sound path is set to an odd multiple of one-quarter of the wavelength of the primary frequency.

[0110] The target equivalent sound path refers to setting the Hilbert channel equivalent sound path to an odd multiple of a quarter wavelength in order to achieve a phase reversal of approximately 180° at the target frequency.

[0111] The wavelength λ0 is calculated from the speed of sound in air c and the target frequency f0, i.e.

[0112] (1)

[0113] To achieve a phase reversal of approximately 180°, the equivalent path of the Hilbert channel is set to an odd multiple of a quarter wavelength:

[0114] (2)

[0115] Among them, L target This is the target equivalent sound path of the Hilbert channel.

[0116] S302: Based on the target radiation surface parameters, determine the side length and height of a single Hilbert acoustic cell, and select the order of the Hilbert curve.

[0117] In this context, the order N of the Hilbert curve refers to the number of iterations of the fractal curve. When N=2, 3, and 4, the plane is divided into 4×4, 8×8, and 16×16 subgrids, respectively. The higher the order, the longer the channel path length that can be achieved. The side length a and height H refer to the external geometric dimensions of the cell, which are subject to the spatial constraints available behind the target radiation surface.

[0118] For example, based on the available space inside the shell behind the target radiating surface, the outer side length a and height H of the unit cell are determined. Given a, the order N of the Hilbert curve is selected. The order N can be 2, 3 or 4. The higher the N, the longer the sound path can be. After the order N of the Hilbert curve is determined, the plane is divided into 2N×2N subgrids. The channel traverses these grids sequentially along the Hilbert trajectory to form the sound channel.

[0119] S303: Based on the processing technology and the required thickness of the sound-absorbing layer, the width and thickness of the Hilbert channel are selected.

[0120] Here, the channel width b refers to the lateral dimension of the Hilbert channel, and the channel thickness c refers to the longitudinal dimension of the channel. Both must meet the manufacturing limit size requirements, and sufficient thickness must be reserved for the sound-absorbing layer to ensure that an effective sound channel can still be formed after subtracting the sound-absorbing layer thickness from the channel width.

[0121] For example, considering the processing technology and the required thickness of the sound-absorbing layer, the initial selection of channel width b and thickness c satisfies the following conditions: First, it meets the manufacturing limit dimensions, for example: b ≥ b min c≥c min Secondly, the initial channel width 'b' needs to reserve a certain thickness for the sound-absorbing layer, ensuring that the effective sound channel still exists even after subtracting the sound-absorbing layer thickness from the channel width. For the Hilbert structure, the following approximate conditions can be met between the side lengths:

[0122] (3)

[0123] Therefore, given N and processing capacity, we can adjust b and c to make a meet the installation space constraints, or under a given a, we can solve for a suitable b+c, and then divide the specific values ​​of b and c based on this.

[0124] S304: Based on the order of the Hilbert curve and the width and thickness of the Hilbert channel, a three-dimensional Hilbert channel model is constructed, and the total path length of the channel centerline of the three-dimensional Hilbert channel model is used as an approximation of the equivalent sound path.

[0125] The equivalent sound path approximation refers to the total path length L of the Hilbert channel centerline measured by acoustic simulation software. path As the equivalent sound path L eff The first approximation; in fine design, the equivalent phase delay can be corrected by combining finite element simulation, and the phase delay obtained from the simulation can be converted into the corrected L. eff .

[0126] For example, in simulation software, based on the selected order N, channel width b, and thickness c, the channel centerline is drawn according to the standard Hilbert curve generation rules, and a channel cross-section with width b is generated around the centerline to obtain a complete three-dimensional Hilbert channel model; the length of the channel centerline is measured using acoustic simulation software to obtain the total internal channel path length L. path Considering the effects of end expansion, inlet / outlet orifices, and actual sound field distribution, it can be used as the first approximation of the equivalent sound path, i.e.:

[0127] (4)

[0128] When fine design is required, the equivalent phase delay can be corrected by combining finite element simulation, and the phase delay obtained from the simulation can be converted into the corrected L. eff .

[0129] S305: Based on the error between the target equivalent sound path and the approximate equivalent sound path, iteratively correct various geometric parameters of a single Hilbert acoustic cell until the error is within the set range.

[0130] Among them, the error setting range refers to the approximate value of the equivalent sound path L. eff Equivalent sound path L to the target target The deviation is usually taken as ±10%; the iterative correction process is as follows: first, calculate the error between the current equivalent sound path approximation and the target equivalent sound path, select the corresponding parameter adjustment method according to the error direction, recalculate the equivalent sound path approximation after adjustment, and judge the error again. Repeat this process until the error meets the requirements; the correction methods include increasing the Hilbert order N, increasing the external size a, lengthening the local channel segment to increase the path length, or reducing the order and reducing the external size to avoid over-design.

[0131] For example, the calculated L eff L obtained from the target frequency in step S301 target Compare, if L eff Approaching L target (For example, if the error is within ±10%), then the combination of geometric parameters is considered to meet the phase design requirements; if L eff Significantly smaller than L target The path length can be increased by increasing the Hilbert order N, increasing the overall size a, or appropriately lengthening local channel segments; if L eff Much larger than L target If the error is too high, the order can be appropriately reduced or the external dimension 'a' can be decreased to avoid over-design until the error meets the requirements.

[0132] S306: Integrate the final Hilbert curve order, the side length and height of a single Hilbert acoustic cell, and the width and thickness of the Hilbert channel to obtain the Hilbert acoustic cell parameter set.

[0133] The parameter set refers to the final determined Hilbert order N, side length a, height H, channel width b, thickness c, and sound-absorbing layer thickness, etc., which are used for standardized cell design and multi-cell array layout.

[0134] This embodiment constructs a basic cell that can generate deep absorption at the target even harmonics, solving the technical problems of insufficient high-frequency sound path and inability to achieve phase control in traditional single-cavity structures. It forms a standardized set of cell parameters, improving the accuracy and consistency of cell sound absorption. The fractal acoustic cell construction method based on Hilbert curves implemented in this embodiment, by adjusting the Hilbert order, external dimensions, and channel geometry parameters, enables sound waves to form an equivalent propagation path far exceeding the geometric dimensions within a limited space. This achieves phase reversal of a quarter wavelength near the target frequency, generating deep absorption at multiple even harmonics. This is a Hilbert fractal channel design technology for high-frequency transformer harmonic noise.

[0135] In an exemplary embodiment, a multi-cell array layout is designed based on the Hilbert acoustic cell parameter set to obtain multi-cell coupled Hilbert array parameters, including:

[0136] S401: For the available installation area of ​​the target radiation surface, a multi-cell array is formed by a preset arrangement.

[0137] The preset arrangement refers to arrays such as 2×2 and 3×3, which need to cover the main noise area of ​​the target radiation surface, while reserving installation and heat dissipation gaps.

[0138] For example, within the available area of ​​the target radiation surface, multiple Hilbert cells are arranged in an array structure according to a 2×2, 3×3 or other arrangement, so that the array covers the main noise radiation area of ​​the surface, while reserving installation and heat dissipation gaps.

[0139] S402: Differentiate the size and order of each Hilbert acoustic cell in the multi-cell array to stagger the resonant center frequency distribution of each Hilbert acoustic cell.

[0140] Among them, staggered peak distribution refers to the sequential arrangement of the resonant center frequencies of each cell within the target frequency band to avoid frequency overlap and form a continuous sound absorption zone, thus solving the problem of narrow sound absorption peaks and easy sound absorption valleys in single cells.

[0141] For example, to broaden the absorption bandwidth, multi-cell coupling is formed in the following way: some cells maintain the same order N and similar external dimensions a, corresponding to the same center frequency; other cells are adjusted by fine-tuning a, changing the order N, or adjusting the channel width b to make their equivalent path length L. eff,i Slightly different, corresponding to several adjacent but different resonant center frequencies f 0,i In this way, multiple absorption peaks are staggered across a wide frequency range, and when superimposed, they form a continuous broadband absorption region, avoiding absorption valleys between individual cells.

[0142] S403: Optimize the acoustic input impedance of each Hilbert acoustic cell, determine the absorption characteristics of each Hilbert acoustic cell, and match the corresponding parameters.

[0143] Among them, the acoustic input impedance Z i The aperture is a physical quantity that characterizes the ability of sound energy to couple into the cell interior; the formula is:

[0144] (5)

[0145] Where ρ is the air density, c is the speed of sound in air, and S t,i Let l be the cross-sectional area of ​​the small hole. e,i The equivalent length of the aperture is given by ω = 2πf, where ω is the angular frequency; high-Q unit target |Z i |≈5~20Z0, Low Q cell target|Z i |≈0.5~3Z0 (Z0=ρc≈411.6Pa·s / m).

[0146] Coupling performance refers to the ability of acoustic energy to couple into the cell, determined by the acoustic input impedance Z. i Direct characterization, Z i The size of the cell determines the proportion of incident acoustic energy that enters the cell. The absorption characteristics are divided into two types: high-Q narrowband resonant absorption and low-Q broadband dissipative absorption, which correspond to different acoustic input impedance target ranges. Among them, the high-Q unit corresponds to a larger input impedance, and the low-Q unit corresponds to a smaller input impedance.

[0147] For example, each cell is connected to the internal air cavity of the transformer housing through inlet and outlet orifices. The target range of input impedance is set according to the cell function (high Q / low Q), which simultaneously corresponds to the cell's coupling performance and absorption characteristics requirements. Initial selection of orifice geometry parameters and calculation of impedance are performed, and the orifice parameters are fine-tuned to achieve Z... i It falls into the target range, achieving accurate control of the acoustic energy coupling strength.

[0148] S404: Cover the channel wall of each Hilbert acoustic cell with an electrically insulating porous sound-absorbing layer, integrate and optimize the parameters of each Hilbert acoustic cell, and obtain the parameters of the multi-cell coupled Hilbert array.

[0149] Among them, the electrically insulating porous sound-absorbing layer refers to the insulating porous material covering the inner wall of the channel, which is used to increase sound energy dissipation and meet the insulation requirements of the transformer. Different cells can use sound-absorbing materials with slightly different thicknesses or flow resistance parameters.

[0150] For example, an electrically insulating porous sound-absorbing material is uniformly covered on the channel wall of each Hilbert cell. Different cells use sound-absorbing materials with slightly different thicknesses or flow resistance parameters, so that some cells are biased towards high-Q resonant absorption and some cells are biased towards low-Q broadband dissipation. After integrating and optimizing all parameters of each Hilbert acoustic cell, the parameters of the multi-cell coupled Hilbert array are obtained.

[0151] This embodiment enables a broadband sound absorption design for a multi-cell coupled Hilbert array. By comprehensively covering the noise region of the target radiating surface through array layout, fine-tuning the cell size and order achieves a staggered distribution of resonant frequencies, adjusting the aperture parameters to control the acoustic input impedance, and combining this with a differentiated sound-absorbing layer configuration to achieve synergistic high-Q and low-Q sound absorption characteristics. Ultimately, this results in a continuous distribution of absorption peaks for each cell within the target frequency band, eliminating the shortcomings of traditional single-cell absorption peaks and deep absorption valleys. It achieves a flexible combination of high-Q narrow-band deep absorption and low-Q broadband dissipation, broadening the absorption bandwidth and forming a complete array design parameter scheme. The multi-cell coupled Hilbert array broadband sound absorption technology in this embodiment, by arranging multiple Hilbert acoustic cells with differentiated parameters on the target radiating surface, and by differentiating the acoustic impedance of the entrance aperture, channel size, and resonant center frequency, allows the absorption peaks of each cell to be staggered within the target frequency band, forming a continuous broadband absorption region to suppress high-frequency transformer broadband noise and multi-order harmonic components.

[0152] In one exemplary embodiment, acoustic input impedance and coupling optimization includes:

[0153] S501: Based on the main frequency, determine the function of each Hilbert acoustic cell in the multi-cell array and set the corresponding input impedance target range; the functions include high-Q narrowband resonant absorption and low-Q broadband dissipation absorption.

[0154] Among them, high-Q narrowband resonant absorption refers to cell absorption peaks with sharpness and strong frequency selectivity, used for deep absorption of dominant harmonics; low-Q broadband dissipative absorption refers to cell absorption peaks with wide frequency coverage, used to fill absorption valleys; the quality factor Q of Hilbert fractal acoustic cells is defined as:

[0155] (6)

[0156] In the formula, f0 is the resonant center frequency, and Δf is the effective bandwidth when its sound absorption coefficient drops to half of its peak value.

[0157] A higher Q value indicates that the cell has stronger frequency selectivity, with sharper and deeper absorption peaks but narrower bandwidth; a lower Q value indicates wider absorption peaks, a wider frequency domain coverage but lower peak values.

[0158] For example, based on noise test results, the target frequency f0 to be processed is selected, and the function of each Hilbert cell in the array is determined to be either high-Q resonance or low-Q broadband dissipation, thereby setting the target range of input impedance (high-Q cell target: |Z i |≈5~20Z0; Low Q unit target: |Z i |≈0.5~3Z0), where Z0=ρc≈411.6Pa·s / m.

[0159] S502: Under the constraint of the frontal area of ​​the Hilbert acoustic cell, the geometric parameters of the small hole are initially selected proportionally; the small hole is the connecting hole between the Hilbert acoustic cell and the air cavity inside the transformer housing.

[0160] The geometric parameters of the pinholes include their location, number, diameter d, and equivalent length l. e,i ;l e,i ≈l 板厚 +αr, where l 板厚 The actual thickness of the transformer housing + Hilbert shell is given, r is the hole radius, and α is the end correction factor (0.8~1.7). The total area of ​​the small holes in high-Q units is approximately 1%~3% of the unit's front area, and in low-Q units it is approximately 5%~15%. The cross-sectional area of ​​the small holes is S. t,i =πd 2 / 4.

[0161] For example, given the frontal area constraint of a Hilbert element, the position and number of holes are selected, and the cross-sectional area S is initially selected using the ratio of the hole area to the frontal area of ​​the element. t,i Calculate S based on the diameter d of the circular hole. t,i The equivalent length l is determined by combining the shell thickness and end correction. e,i .

[0162] S503: Adjust the geometric parameters so that the acoustic input impedance of each Hilbert acoustic cell falls within the target range of input impedance.

[0163] The adjustment methods include changing the hole diameter d, the number of holes, and l. 板厚 The end correction factor α, or the thickness of the sound-absorbing layer, can be adjusted to change the flow resistance; if |Z i |Too large, increase d and decrease l e,i Or thicken the sound-absorbing layer; if |Z i |Too small, decrease d and increase l e,i Or reduce the thickness of the sound-absorbing layer.

[0164] For example, the input impedance is calculated using the impedance formula, and the relevant parameters are substituted at the target frequency f0. If |Z i If it's too large, you can increase the diameter d of the hole and decrease l. e,iOr thicken the sound-absorbing layer; if |Z i |Too small, decrease d and increase l e,i Or reduce the thickness of the sound-absorbing layer until |Z i | It falls within the predetermined range.

[0165] S504: By combining the equivalent path length of the Hilbert acoustic cell channel and the sound absorption layer flow resistance parameters, the resonant frequency and absorption bandwidth of the Hilbert acoustic cell are verified, and the parameters of each Hilbert acoustic cell in the multi-cell array are coordinated until the entire array forms a continuous broadband sound absorption zone within the target wideband range.

[0166] Among them, verification refers to verifying whether the cell resonant frequency and absorption bandwidth meet the design requirements through simulation or prototype testing; coordination refers to adjusting the parameters of each cell so that the entire array forms a continuous sound absorption zone within the target frequency band and avoids sound absorption valleys.

[0167] Optionally, a cell model can be established using finite element acoustic simulation software to calculate the sound absorption coefficient spectrum and verify the resonant frequency and bandwidth. If sound absorption valleys exist, the equivalent sound path or acoustic input impedance of adjacent cells can be finely adjusted to make the sound absorption peaks connect smoothly.

[0168] This embodiment of the coupling enhancement method based on the acoustic input impedance control of inlet / outlet pinholes divides high-Q and low-Q cells according to noise reduction requirements and sets the target impedance range. By adjusting the diameter, number, equivalent length, and sound-absorbing layer thickness of the pinholes, the acoustic input impedance of each cell falls within the target range. The sound absorption performance is verified through simulation or prototype testing, and the array parameters are coordinated to accurately control the acoustic coupling strength of each cell. This ensures that high-Q cells achieve deep absorption of dominant harmonics, and low-Q cells fill the sound absorption valleys, so that the entire array forms a continuous broadband sound absorption zone without sound absorption valleys. This improves the coordination and stability of multi-cell coupling and further enhances the broadband noise reduction effect.

[0169] In an exemplary embodiment, after constructing the Hilbert array module based on the parameters of the multi-cell coupled Hilbert array, a noise reduction effect evaluation step is further included, comprising:

[0170] S601: Install the Hilbert array module in the available mounting area behind the target radiating surface.

[0171] The available installation area refers to the neutral potential area behind the target radiating surface, which must meet the requirements for insulation distance and heat dissipation. The module shell must be reliably connected to the transformer shell and grounded to avoid partial discharge caused by floating potential.

[0172] For example, the Hilbert array module is fixed in the neutral potential region inside the housing behind the target radiating surface to ensure reliable conduction and grounding between the array housing and the transformer housing; confirm that the minimum insulation distance between the array and high-potential components such as windings and wires meets the design and specification requirements, and reserve cooling air channels in necessary locations.

[0173] S602: Under the rated operating conditions of a high-frequency transformer, noise is measured using a hexahedral measuring point arrangement method to obtain the overall radiated sound power level of the transformer after noise reduction.

[0174] Among them, the noise data after noise reduction refers to the sound pressure data of each measuring point and the overall radiated sound power level of the transformer after the module is installed and under the same working conditions.

[0175] For example, under the same operating conditions before and after the device installation, the noise measurement method of step S201 is repeated, and the measuring points are arranged using the hexahedral measuring point arrangement method conforming to GB / T 3767-2016. The sound pressure of each measuring point is measured with a microphone to obtain the sound pressure spectrum of each measuring point before and after noise reduction and the sound power level radiated by the transformer as a whole.

[0176] S603: For the target harmonic frequencies corresponding to each major frequency, calculate the sound pressure reduction before and after noise reduction based on the overall radiated sound power level of the transformer, and complete the evaluation of the noise reduction effect.

[0177] For each target harmonic frequency f n The corresponding sound pressure drop ΔL p (f n The formula for calculating ) is:

[0178] (7)

[0179] In the formula, L p,before (f n ) is the harmonic frequency f n The sound pressure level before noise reduction, L p,after (f n ) is the harmonic frequency f n Sound pressure level after noise reduction.

[0180] In this embodiment, the array module is installed in the neutral potential area of ​​the transformer to ensure that insulation and heat dissipation constraints are met and reliable grounding is achieved. Comparative data is obtained by repeating the standardized noise measurement process. The noise reduction effect of the target frequency is calculated by the sound pressure reduction formula, the sound pressure reduction of each target harmonic frequency is accurately quantified, the technical effectiveness of the aforementioned design steps is verified, and the device installation process is standardized to ensure that the device achieves efficient noise reduction without affecting the normal operation of the transformer.

[0181] Compared with existing high-frequency transformer noise reduction technologies, this invention has significant advantages in sound absorption efficiency, frequency domain coverage, structural compactness, adjustability, and overall noise reduction performance.

[0182] Traditional methods such as damping layers, external sound-absorbing materials, and composite shells mainly rely on passive material dissipation. The sound absorption peaks are mostly concentrated in the mid-to-low frequency range, and the sound absorption efficiency is significantly reduced in the kHz high frequency range. It is difficult to suppress multi-order even-order harmonic noise generated by magnetostriction and electromagnetic force coupling. Furthermore, phase modulation cannot be achieved, the absorption peaks are discrete, and there are obvious absorption valleys between the peaks, resulting in discontinuous and unstable noise reduction effects. At the same time, large sound-absorbing covers and composite sound insulation panels are bulky and can easily obstruct cooling air passages, making them difficult to integrate and use inside compact transformers.

[0183] This invention utilizes a Hilbert fractal structure to create an ultra-long equivalent sound path, enabling the construction of a kHz-level high-efficiency phase-reversal cavity within a limited space while maintaining strong sound absorption capabilities at high frequencies. Through multi-cell coupling, it achieves peak-shifting combinations of absorption peaks, forming a continuous sound absorption response across a wide frequency band and effectively filling the absorption valleys of traditional structures. Furthermore, by differentiating the inlet impedance, cell geometry parameters, and sound-absorbing laminar flow resistance, the Q-value of each cell can be flexibly adjusted to achieve a controllable distribution of deep and wide absorption, adapting to broadband noise reduction requirements under different operating conditions.

[0184] Specifically, by placing a thinner sound-absorbing layer on the channel walls of some Hilbert cells, reducing the channel width *b*, and decreasing the cross-sectional area of ​​the inlet aperture, high-Q narrowband resonant characteristics are achieved to deeply absorb the dominant even harmonics of the noise frequency. In other cells, by increasing the channel width or using a thicker sound-absorbing layer, low-Q broadband absorption characteristics are achieved to fill the absorption valleys between the absorption peaks of the high-Q cells, thus realizing continuous broadband absorption across multiple frequency bands. Through the coupled arrangement of high-Q and low-Q cells, an overall noise reduction effect that combines deep absorption and broadband bandwidth is obtained.

[0185] In one exemplary embodiment, the present invention also provides a multi-cell coupled Hilbert fractal array sound absorption and noise reduction device, comprising:

[0186] Multiple Hilbert acoustic cells and rigid substrates;

[0187] Each Hilbert acoustic cell is provided with a channel extending along the Hilbert curve, an electrically insulating porous sound-absorbing layer covering the channel wall, and a small hole communicating with the air cavity inside the high-frequency transformer housing.

[0188] The parameters of each Hilbert acoustic cell are set based on the multi-cell coupled Hilbert array parameters determined by the multi-cell coupled Hilbert fractal array sound absorption and noise reduction method described in the foregoing embodiments.

[0189] Multiple Hilbert acoustic cells are assembled on a rigid substrate in a preset arrangement to form a Hilbert array module.

[0190] The rigid substrate has a mechanical connection structure for securing the Hilbert array module to the available mounting area behind the target radiating surface of the high-frequency transformer.

[0191] The design of the aforementioned device is based on the equivalent ultra-long sound path characteristics of Hilbert fractal structures, the multi-cell staggered absorption principle, and acoustic input impedance control technology. Hilbert acoustic cells construct labyrinthine sound channels through fractal curves, achieving an equivalent propagation path far exceeding geometric dimensions within a limited space. This satisfies the quarter-wavelength phase reversal condition of the target even-order harmonic frequency, thereby achieving efficient absorption of kHz-level broadband noise. The multi-cells are assembled according to a preset array layout. Through differentiated design of geometric parameters, order, input impedance, and sound-absorbing layer parameters, the resonant center frequencies of each cell are staggered, forming a continuous broadband sound-absorbing zone that effectively suppresses high-frequency transformer broadband noise and multi-order harmonic components. The device adopts a modular design, achieving reliable fixation to the transformer shell through a mechanical connection structure of a rigid substrate. It is installed in the neutral potential area behind the target radiating surface, satisfying the transformer insulation distance requirements while reserving cooling air channels to avoid affecting the equipment's heat dissipation performance. At the same time, the array shell and the transformer shell are reliably grounded to ensure electrical safety.

[0192] In addition, Hilbert cells can be manufactured by 3D printing technology to form the Hilbert channel body in one piece, using high-strength insulating resin or nylon; or by processing a metal block to form a labyrinth channel, then spraying or pasting porous sound-absorbing material on its inner surface, and covering it with a conductive metal shell.

[0193] In summary, this device has a compact structure and is easy to integrate. It can effectively suppress high-frequency noise radiation while ensuring the compact structure and high power density of the high-frequency transformer. It solves the problems of low high-frequency sound absorption efficiency, discontinuous frequency band, large size, and impact on heat dissipation and insulation of existing noise reduction technologies. It has good engineering adaptability and efficient broadband noise reduction effect.

[0194] This embodiment achieves wideband continuous sound absorption through multi-cell differentiated design. By modular installation and insulation and heat dissipation adaptation design, it achieves precise integration of the device with the internal structure of the transformer. This solves the technical problems of low high-frequency sound absorption efficiency, discontinuous frequency band, large size, and impact on heat dissipation and insulation of traditional damping and external sound-absorbing cotton technologies. It achieves efficient suppression of kHz-level broadband noise in a limited space. The device parameters are adjustable and the structure is compact. It can be directly integrated into the transformer without increasing the shell volume or affecting the normal operation of the equipment, thus improving the technical level and engineering adaptability of high-frequency transformer noise reduction.

[0195] Based on the same inventive concept, this application also provides a multi-cell coupled Hilbert fractal array sound absorption and noise reduction system for implementing the multi-cell coupled Hilbert fractal array sound absorption and noise reduction method described above. The solution provided by this system is similar to the implementation scheme described in the above method. Therefore, the specific limitations in the embodiments of the multi-cell coupled Hilbert fractal array sound absorption and noise reduction system provided below can be found in the limitations of the multi-cell coupled Hilbert fractal array sound absorption and noise reduction method described above, and will not be repeated here.

[0196] Please see Figure 2 Embodiments of the present invention also provide a multi-cell coupled Hilbert fractal array sound absorption and noise reduction system, comprising:

[0197] The noise parameter determination unit is used to determine the main frequency and target radiation surface parameters of the transformer radiated noise based on the noise measurement data of the high-frequency transformer under rated operating conditions.

[0198] The unit cell parameter determination unit is used to determine the geometric parameters of a single Hilbert acoustic cell based on the main frequency and target radiation surface parameters, and to obtain the Hilbert acoustic cell parameter set based on the geometric parameters.

[0199] The multi-cell array parameter design unit is used to design the multi-cell array layout based on the Hilbert acoustic cell parameter set, and obtain the multi-cell coupled Hilbert array parameters. The multi-cell array layout design is to adjust the geometric parameters of each cell so that the resonant center frequency of each cell forms a continuous broadband sound absorption area covering the target wideband range.

[0200] The noise suppression module construction unit is used to construct a Hilbert array module based on the parameters of the multi-cell coupled Hilbert array in order to suppress high-frequency noise in high-frequency transformers.

[0201] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the above-described division of functional units and modules is merely an example. In practical applications, the above functions can be assigned to different functional units and modules as needed, that is, the internal structure of the system can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiments can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit. Furthermore, the specific names of the functional units and modules are only for easy differentiation and are not intended to limit the scope of protection of this application. The specific working process of the units and modules in the above system can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0202] Reference Figure 3 This invention also provides a computer device, including: a memory and a processor, and a computer program stored in the memory. When the computer program is executed on the processor, it performs the following steps:

[0203] Based on the noise measurement data of the high-frequency transformer under rated operating conditions, the main frequency and target radiation surface parameters of the transformer radiated noise are determined.

[0204] Based on the main frequency and target radiation surface parameters, the geometric parameters of a single Hilbert acoustic cell are determined, and the set of Hilbert acoustic cell parameters is obtained based on the geometric parameters.

[0205] The multi-cell array layout is designed based on the Hilbert acoustic cell parameter set to obtain the multi-cell coupled Hilbert array parameters. The multi-cell array layout design involves adjusting the geometric parameters of each cell so that the resonant center frequency of each cell forms a continuous broadband sound absorption zone covering the target wideband range.

[0206] Hilbert array modules are constructed based on multi-cell coupled Hilbert array parameters to suppress high-frequency noise in high-frequency transformers.

[0207] In one embodiment, the main frequency and target radiating surface parameters of the transformer radiated noise are determined based on noise measurement data under rated operating conditions of the high-frequency transformer, including:

[0208] A hexahedral measuring point arrangement method was used to obtain noise measurement data of high-frequency transformers under rated operating conditions;

[0209] The main frequencies of transformer radiated noise are extracted by performing a Fourier transform on the noise sound pressure in the noise measurement data.

[0210] The surface with the strongest noise is identified as the target radiating surface, and the radiating surface size and available installation area parameters of the target radiating surface are obtained to obtain the target radiating surface parameters.

[0211] In one embodiment, determining the geometric parameters of a single Hilbert acoustic cell and obtaining a set of Hilbert acoustic cell parameters based on the geometric parameters includes:

[0212] Determine the target equivalent acoustic path of the Hilbert channel based on the primary frequency; the target equivalent acoustic path is set to an odd multiple of one-quarter of the wavelength of the primary frequency.

[0213] Based on the target radiation surface parameters, determine the side length and height of a single Hilbert acoustic cell, and select the order of the Hilbert curve;

[0214] Based on the processing technology and the required thickness of the sound-absorbing layer, the width and thickness of the Hilbert channel were selected.

[0215] Based on the order of the Hilbert curve and the width and thickness of the Hilbert channel, a three-dimensional Hilbert channel model is constructed, and the total path length of the channel centerline of the three-dimensional Hilbert channel model is used as the equivalent sound path approximation.

[0216] Based on the error between the target equivalent sound path and the approximate equivalent sound path, iteratively correct various geometric parameters of a single Hilbert acoustic cell until the error is within the set range;

[0217] By integrating the final Hilbert curve order, the side length and height of a single Hilbert acoustic cell, and the width and thickness of the Hilbert channel, a set of Hilbert acoustic cell parameters is obtained.

[0218] In one embodiment, a multi-cell array layout design is performed based on the Hilbert acoustic cell parameter set to obtain multi-cell coupled Hilbert array parameters, including:

[0219] For the available installation area of ​​the target radiation surface, a multi-cell array is formed by a preset arrangement;

[0220] Differentiated adjustment of the size and order of each Hilbert acoustic cell in the multi-cell array to stagger the resonant center frequency distribution of each Hilbert acoustic cell;

[0221] Optimize the acoustic input impedance and coupling performance of each Hilbert acoustic cell, determine the absorption characteristics of each Hilbert acoustic cell and match the corresponding parameters;

[0222] An electrically insulating porous sound-absorbing layer is covered on the channel wall of each Hilbert acoustic cell. The parameters of each Hilbert acoustic cell are integrated and optimized to obtain the parameters of the multi-cell coupled Hilbert array.

[0223] In one embodiment, acoustic input impedance and coupling optimization includes:

[0224] Based on the main frequency, determine the function of each Hilbert acoustic cell in the multi-cell array and set the corresponding input impedance target range; the functions include high-Q narrowband resonant absorption and low-Q broadband dissipative absorption.

[0225] Under the constraint of the frontal area of ​​the Hilbert acoustic cell, the geometric parameters of the small hole are initially selected proportionally; the small hole is the connecting hole between the Hilbert acoustic cell and the air cavity inside the transformer housing.

[0226] Adjust the geometric parameters so that the acoustic input impedance of each Hilbert acoustic cell falls within the target range of input impedance;

[0227] By combining the equivalent path length of the Hilbert acoustic cell channel and the flow resistance parameters of the sound-absorbing layer, the resonant frequency and absorption bandwidth of the Hilbert acoustic cell are verified, and the parameters of each Hilbert acoustic cell in the multi-cell array are coordinated until the entire array forms a continuous broadband sound-absorbing zone within the target wideband range.

[0228] In one embodiment, after constructing the Hilbert array module based on the parameters of the multi-cell coupled Hilbert array, a noise reduction effect evaluation step is further included, comprising:

[0229] Install the Hilbert array module in the available mounting area behind the target radiating surface;

[0230] Noise measurement was performed on a high-frequency transformer under rated operating conditions using a hexahedral measuring point arrangement method to obtain the overall radiated sound power level of the transformer after noise reduction.

[0231] For each major frequency corresponding to the target harmonic frequency, the sound pressure reduction before and after noise reduction is calculated based on the overall radiated sound power level of the transformer, and the noise reduction effect is evaluated.

[0232] The computer device may be a desktop computer, laptop, handheld computer, or cloud server, etc. This computer device may include, but is not limited to, a processor and memory. Those skilled in the art will understand that... Figure 3 The examples of computer devices are merely examples and do not constitute a limitation on computer devices. They may include more or fewer components than shown in the illustration, or combinations of certain components, or different components. For example, they may also include input / output devices, network access devices, etc.

[0233] The processor referred to can be a Central Processing Unit (CPU), but it can also be other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor can be a microprocessor or any conventional processor.

[0234] In some embodiments, the memory may be an internal storage unit of the computer device, such as a hard drive or RAM. In other embodiments, the memory may be an external storage device of the computer device, such as a plug-in hard drive, Smart Media Card (SMC), Secure Digital (SD) card, or Flash Card. Furthermore, the memory may include both internal and external storage units of the computer device. The memory is used to store the operating system, applications, boot loader, data, and other programs, such as the program code of the computer program. The memory can also be used to temporarily store data that has been output or will be output.

[0235] This invention also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, performs the following steps:

[0236] Based on the noise measurement data of the high-frequency transformer under rated operating conditions, the main frequency and target radiation surface parameters of the transformer radiated noise are determined.

[0237] Based on the main frequency and target radiation surface parameters, the geometric parameters of a single Hilbert acoustic cell are determined, and the set of Hilbert acoustic cell parameters is obtained based on the geometric parameters.

[0238] The multi-cell array layout is designed based on the Hilbert acoustic cell parameter set to obtain the multi-cell coupled Hilbert array parameters. The multi-cell array layout design involves adjusting the geometric parameters of each cell so that the resonant center frequency of each cell forms a continuous broadband sound absorption zone covering the target wideband range.

[0239] Hilbert array modules are constructed based on multi-cell coupled Hilbert array parameters to suppress high-frequency noise in high-frequency transformers.

[0240] In this embodiment, if the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the various method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. The computer-readable medium can include at least: any entity or device capable of carrying computer program code to a photographing device / terminal device, a recording medium, a computer memory, a read-only memory (ROM), a random access memory (RAM), an electrical carrier signal, a telecommunication signal, and a software distribution medium. Examples include USB flash drives, portable hard drives, magnetic disks, or optical disks. In some jurisdictions, according to legislation and patent practice, computer-readable media cannot be electrical carrier signals or telecommunication signals.

[0241] This invention provides a computer program product, including a computer program that, when executed by a processor, performs the following steps:

[0242] Based on the noise measurement data of the high-frequency transformer under rated operating conditions, the main frequency and target radiation surface parameters of the transformer radiated noise are determined.

[0243] Based on the main frequency and target radiation surface parameters, the geometric parameters of a single Hilbert acoustic cell are determined, and the set of Hilbert acoustic cell parameters is obtained based on the geometric parameters.

[0244] The multi-cell array layout is designed based on the Hilbert acoustic cell parameter set to obtain the multi-cell coupled Hilbert array parameters. The multi-cell array layout design involves adjusting the geometric parameters of each cell so that the resonant center frequency of each cell forms a continuous broadband sound absorption zone covering the target wideband range.

[0245] Hilbert array modules are constructed based on multi-cell coupled Hilbert array parameters to suppress high-frequency noise in high-frequency transformers.

[0246] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0247] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0248] In the embodiments disclosed in this application, it should be understood that the disclosed devices / terminal equipment and methods can be implemented in other ways. For example, the device / terminal equipment embodiments described above are merely illustrative. For instance, the division of modules or units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the displayed or discussed mutual coupling or direct coupling or communication connection may be through some interfaces; the indirect coupling or communication connection between devices or units may be electrical, mechanical, or other forms.

[0249] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for sound absorption and noise reduction using a multi-cell coupled Hilbert fractal array, characterized in that, Includes the following steps: Based on the noise measurement data of the high-frequency transformer under rated operating conditions, the main frequency and target radiation surface parameters of the transformer radiated noise are determined. Based on the main frequency and the target radiation surface parameters, the geometric parameters of a single Hilbert acoustic cell are determined, and the set of Hilbert acoustic cell parameters is obtained based on the geometric parameters. Based on the set of Hilbert acoustic cell parameters, a multi-cell array layout design is performed to obtain the multi-cell coupled Hilbert array parameters. The multi-cell array layout is designed to adjust the geometric parameters of each cell so that the resonant center frequency of each cell forms a continuous broadband sound absorption zone covering the target wideband range. Based on the parameters of the multi-cell coupled Hilbert array, a Hilbert array module is constructed to suppress high-frequency noise in the high-frequency transformer.

2. The multi-cell coupled Hilbert fractal array sound absorption and noise reduction method according to claim 1, characterized in that, Based on noise measurement data of high-frequency transformers under rated operating conditions, the main frequencies and target radiating surface parameters of the transformer radiated noise are determined, including: A hexahedral measuring point arrangement method was used to obtain noise measurement data of high-frequency transformers under rated operating conditions; Perform a Fourier transform on the noise sound pressure in the noise measurement data to extract the main frequencies of the transformer radiated noise; The surface with the strongest noise is identified as the target radiating surface, and the radiating surface size and available installation area parameters of the target radiating surface are obtained to obtain the target radiating surface parameters.

3. The multi-cell coupled Hilbert fractal array sound absorption and noise reduction method according to claim 1, characterized in that, Determine the geometric parameters of a single Hilbert acoustic cell, and obtain a set of Hilbert acoustic cell parameters based on the geometric parameters, including: Based on the primary frequency, determine the target equivalent acoustic path of the Hilbert channel; the target equivalent acoustic path is set to an odd multiple of one-quarter of the wavelength of the primary frequency; Based on the target radiation surface parameters, determine the side length and height of a single Hilbert acoustic cell, and select the order of the Hilbert curve; Based on the processing technology and the required thickness of the sound-absorbing layer, the width and thickness of the Hilbert channel were selected. Based on the order of the Hilbert curve and the width and thickness of the Hilbert channel, a three-dimensional Hilbert channel model is constructed, and the total path length of the channel centerline of the three-dimensional Hilbert channel model is used as an approximation of the equivalent sound path. Based on the error between the target equivalent sound path and the approximate equivalent sound path, iteratively correct various geometric parameters of a single Hilbert acoustic cell until the error is within a set range; By integrating the final Hilbert curve order, the side length and height of a single Hilbert acoustic cell, and the width and thickness of the Hilbert channel, the set of Hilbert acoustic cell parameters is obtained.

4. The multi-cell coupled Hilbert fractal array sound absorption and noise reduction method according to claim 1, characterized in that, Based on the Hilbert acoustic cell parameter set, a multi-cell array layout design is performed to obtain the multi-cell coupled Hilbert array parameters, including: For the available installation area of ​​the target radiation surface, a multi-cell array is formed by a preset arrangement; The size and order of each Hilbert acoustic cell in the multi-cell array are adjusted differentially to make the resonant center frequency of each Hilbert acoustic cell staggered. Optimize the acoustic input impedance of each Hilbert acoustic cell, determine the absorption characteristics of each Hilbert acoustic cell, and match the corresponding parameters; An electrically insulating porous sound-absorbing layer is covered on the channel wall of each Hilbert acoustic cell. The parameters of each Hilbert acoustic cell are integrated and optimized to obtain the parameters of the multi-cell coupled Hilbert array.

5. The multi-cell coupled Hilbert fractal array sound absorption and noise reduction method according to claim 4, characterized in that, The acoustic input impedance and coupling optimization includes: Based on the main frequency, the function of each Hilbert acoustic cell in the multi-cell array is determined, and the corresponding input impedance target range is set; the function includes high-Q narrowband resonant absorption and low-Q broadband dissipative absorption. Under the constraint of the frontal area of ​​the Hilbert acoustic cell, the geometric parameters of the small hole are initially selected proportionally; the small hole is the connecting hole between the Hilbert acoustic cell and the air cavity inside the transformer housing. Adjust the geometric parameters so that the acoustic input impedance of each Hilbert acoustic cell falls within the target range of input impedance; By combining the equivalent path length of the Hilbert acoustic cell channel and the sound-absorbing layer flow resistance parameters, the resonant frequency and absorption bandwidth of the Hilbert acoustic cell are verified, and the parameters of each Hilbert acoustic cell in the multi-cell array are coordinated until the entire array forms a continuous broadband sound-absorbing region within the target broadband range.

6. The multi-cell coupled Hilbert fractal array sound absorption and noise reduction method according to claim 1, characterized in that, After constructing the Hilbert array module based on the parameters of the multi-cell coupled Hilbert array, the method further includes a noise reduction effect evaluation step, including: The Hilbert array module is installed in an available mounting area behind the target radiating surface; Noise measurement was performed on a high-frequency transformer under rated operating conditions using a hexahedral measuring point arrangement method to obtain the overall radiated sound power level of the transformer after noise reduction. For each major frequency corresponding to the target harmonic frequency, the sound pressure reduction before and after noise reduction is calculated based on the overall radiated sound power level of the transformer, and the noise reduction effect is evaluated.

7. A multi-cell coupled Hilbert fractal array sound absorption and noise reduction device, characterized in that, include: Multiple Hilbert acoustic cells and rigid substrates; Each of the Hilbert acoustic cells is provided with a channel extending along the Hilbert curve, an electrically insulating porous sound-absorbing layer covering the channel wall, and a small hole communicating with the air cavity inside the high-frequency transformer housing; The parameters of each Hilbert acoustic cell are set based on the multi-cell coupled Hilbert array parameters determined by the method of any one of claims 1-6; Multiple Hilbert acoustic cells are assembled on the rigid substrate in a preset arrangement to form a Hilbert array module; The rigid substrate is provided with a mechanical connection structure for fixing the Hilbert array module to the available mounting area behind the target radiating surface of the high-frequency transformer.

8. A multi-cell coupled Hilbert fractal array sound absorption and noise reduction system, characterized in that, include: The noise parameter determination unit is used to determine the main frequency and target radiation surface parameters of the transformer radiated noise based on the noise measurement data of the high-frequency transformer under rated operating conditions. The unit cell parameter determination unit is used to determine the geometric parameters of a single Hilbert acoustic cell based on the main frequency and the target radiation surface parameters, and to obtain a set of Hilbert acoustic cell parameters based on the geometric parameters. A multi-cell array parameter design unit is used to design the multi-cell array layout based on the Hilbert acoustic cell parameter set, and obtain the multi-cell coupled Hilbert array parameters. The multi-cell array layout is designed to adjust the geometric parameters of each cell so that the resonant center frequency of each cell forms a continuous broadband sound absorption zone covering the target wideband range. The noise suppression module construction unit is used to construct a Hilbert array module based on the parameters of the multi-cell coupled Hilbert array to suppress high-frequency noise in the high-frequency transformer.

9. A computer device, characterized in that, The device includes a processor and a memory: The memory is used to store computer programs and send the instructions of the computer programs to the processor; The processor executes a multi-cell coupled Hilbert fractal array sound absorption and noise reduction method as described in any one of claims 1-6 according to the instructions of the computer program.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed by a processor, implements a multi-cell coupled Hilbert fractal array sound absorption and noise reduction method as described in any one of claims 1-6.

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