Modularized active noise reduction method and system

Abstract

The invention belongs to the technical field of active noise reduction, and discloses a modular active noise reduction method and system, and the method comprises the steps: extracting the maximum frequency in a noise frequency band to be subjected to noise reduction; calculating the cut-off frequency of the pipeline to be subjected to noise reduction; taking the larger one of the maximum frequency and the cut-off frequency as a decision frequency, and determining the spacing of the active noise reduction minimum unit module according to the decision frequency; determining the number of active noise reduction minimum unit modules to be set in the pipeline to be subjected to noise reduction based on the length of the pipeline to be subjected to noise reduction and the determined spacing of the active noise reduction minimum unit modules; a plurality of to-be-set active noise reduction minimum unit modules are combined in a centralized, cluster or distributed mode and are arranged in a to-be-noise-reduced pipeline after being combined, and active noise reduction is carried out on a to-be-noise-reduced noise frequency band. According to the invention, active noise control of ventilation equipment with different sizes and different noise sources is rapidly realized, the limitation of front installation of a noise reduction system is reduced, the development period is shortened, and feasibility is provided for rear installation.

Description

Technical Field

[0001] The present invention belongs to the technical field of active noise reduction, and particularly relates to a modular active noise reduction method and system. Background Art

[0002] The principle of traditional noise control technology is to consume sound energy through the interaction between noise sound waves and acoustic materials or acoustic structures, so as to achieve the purpose of reducing noise, which belongs to passive noise control. Active noise control is based on the principle of destructive interference of sound waves. By canceling the sound source (secondary sound source), a radiation sound wave with the same amplitude and opposite phase as the sound wave of the sound source to be canceled (primary sound source) is generated, and they cancel each other out, thus achieving the purpose of reducing noise.

[0003] For traditional passive noise control, the noise control frequency band is directly related to the thickness of the acoustic material. The thicker the material, the lower the frequency that can be controlled. Therefore, for existing white goods and kitchen appliances such as central air conditioners, range hoods, and integrated cooktops, the noise energy is generally concentrated below 1 kHz. If it is necessary to control the low-frequency noise below 1 kHz, a relatively thick sound insulation cotton is required to be effective, which will inevitably affect the ventilation and heat dissipation performance of the equipment. The active noise reduction technology has the advantage of dealing with low-frequency noise. This is because for low-frequency noise, its period is long and the phase change is small, making it easier to be predicted and canceled. Therefore, the active noise control technology can effectively eliminate the noise of equipment such as central air conditioners, range hoods, and integrated cooktops without affecting the ventilation of the equipment.

[0004] The patent with the publication number CN219550800U provides a pipeline with an active noise reduction device and an active noise reduction structure. When this structure is used, only the pipeline with the active noise reduction structure needs to be spliced and connected to the pipeline structure that needs noise reduction, which has the advantage of convenient installation. However, this method will increase the length of the original pipeline and cannot adapt to pipelines of different sizes.

[0005] The target frequency band for active noise reduction is jointly determined by the pipeline size and the energy distribution of the noise source. There are the following problems in the application of active noise reduction: the product development of active noise reduction depends on the structure of the equipment manufacturer and the noise source. Any change in the structure and noise source of the whole equipment may lead to the failure of noise reduction, and the development cycle is long; the product indicators are completed in the factory, and the noise reduction frequency band and noise reduction depth are determined at the time of leaving the factory, and it is impossible to achieve customization of user noise control and post-installation of products. However, different customer groups have different sensitivities to noise reduction, so it cannot be applied to the C-end market.

[0006] Existing active noise cancellation solutions generally require customized development according to the ventilation opening size of specific devices. Different duct sizes require different configurations of active noise cancellation devices. Once the duct size changes, the existing noise cancellation system cannot adapt to the new ventilation duct, and it is necessary to re - conduct sound field analysis and design adaptation of the noise cancellation system, resulting in a long noise cancellation development cycle for new scenarios and new devices and unable to achieve standardized products.

[0007] For example, for ducted central air conditioners, the ventilation opening sizes of different manufacturers and different models are not the same. Taking the ventilation opening length in the 70 - cm range as an example, the air supply opening length of the Midea MDV - D36 model is 78 cm, the air supply opening length of the Midea MDV - D45d model is 81 cm, the air supply opening length of the Gree GMV - R40 model is 74 cm, the air supply opening length of the Mitsubishi FDUM71 model is 77 cm, and the air supply opening length of the Mitsubishi FDUT45 model is 70 cm. Different duct sizes also have an impact on the noise inside the duct, and the same active noise cancellation solution cannot be reused for devices with different duct sizes.

[0008] At the same time, the energy distributions of different noise sources are different. Even if the duct size remains unchanged, the original noise cancellation system cannot be applied to new noise sources, which will also lead to a significant reduction in the noise cancellation effect. Taking the range hood as an example, the sizes of the smoke collection cavities are not very different, but the energy distributions of the noise sources of different range hoods vary greatly. For example, for the Fangtai X1S range hood, the main energy of the fan noise is concentrated below 800 Hz, accounting for 80%, but for another range hood Y1Pro of the same size, the main energy of the fan noise is concentrated below 600 Hz, accounting for 80%.

[0009] In addition, for users' high - standard noise cancellation requirements, such as focusing on noise control in certain frequency bands, the existing technical solutions cannot be flexibly adjusted and cannot meet users' needs. Summary of the Invention

[0010] The purpose of the present invention is to provide a modular active noise cancellation method and system. By designing a modular minimum active noise cancellation unit, it can quickly achieve active noise control for ventilation equipment with different sizes and different noise sources. At the same time, the modular active noise cancellation units can be flexibly configured according to the frequency bands that need to be noise - cancelled, reducing the limitations of pre - installation of the noise cancellation system, shortening the development cycle, and providing feasibility for post - installation.

[0011] To achieve the above - mentioned purpose, the technical solutions adopted by the present invention are as follows:

[0012] In the first aspect: Provide a modular active noise cancellation method, including:

[0013] Extract the maximum frequency in the noise frequency band to be noise - cancelled;

[0014] Calculate the cut - off frequency of the duct to be noise - cancelled;

[0015] Take the larger of the maximum frequency and the cut-off frequency as the decision frequency, and determine the spacing of the minimum active noise reduction unit modules according to the decision frequency;

[0016] Based on the length of the pipeline to be noise-reduced and the determined spacing of the minimum active noise reduction unit modules, determine the number of minimum active noise reduction unit modules to be set in the pipeline to be noise-reduced;

[0017] Adopt a centralized, clustered or decentralized combination of multiple minimum active noise reduction unit modules to be set, and arrange them in the pipeline to be noise-reduced after combination to perform active noise reduction on the noise frequency band to be noise-reduced.

[0018] The following also provides several optional methods, which are not additional limitations to the above overall solution, but are only further supplements or optimizations. Without technical or logical contradictions, each optional method can be combined with the above overall solution alone, or multiple optional methods can be combined with each other.

[0019] Preferably, the method for determining the noise frequency band to be noise-reduced is as follows:

[0020] Directly set the noise frequency band as the noise frequency band to be noise-reduced;

[0021] Or, collect the noise signal in the pipeline, perform spectral energy analysis on the noise signal, and determine the main energy concentration frequency band of the noise signal as the noise frequency band to be noise-reduced.

[0022] Preferably, the calculation of the cut-off frequency of the pipeline to be noise-reduced includes:

[0023] For a rectangular pipeline to be noise-reduced, the cut-off frequency is calculated as follows:

[0024]

[0025] In the formula, f c represents the cut-off frequency, v represents the sound wave propagation speed, l x and l y respectively represent the length and width of the cross-section of the rectangular pipeline to be noise-reduced. If l x > l y , then n x = 1, n y = 0; otherwise n x = 0, n y = 1;

[0026] For a circular pipeline to be noise-reduced, the cut-off frequency is calculated as follows:

[0027]

[0028] Wherein, r represents the radius of the circular pipeline to be noise-reduced.

[0029] Preferably, determining the spacing of the active noise reduction minimum unit modules according to the decision frequency includes:

[0030] Calculating the wavelength of the decision frequency as follows:

[0031]

[0032] Wherein, λ represents the wavelength, v represents the sound wave propagation speed, and f represents the decision frequency;

[0033] Taking half of the wavelength as the spacing of the active noise reduction minimum unit modules.

[0034] Preferably, determining the number of active noise reduction minimum unit modules to be set in the pipeline to be noise-reduced based on the length of the pipeline to be noise-reduced and the determined spacing of the active noise reduction minimum unit modules includes:

[0035] Dividing the length of the pipeline to be noise-reduced by the determined spacing of the active noise reduction minimum unit modules to obtain the direct number;

[0036] Rounding up or down the direct number as the number of active noise reduction minimum unit modules to be set.

[0037] Preferably, the centralized working mode is: selecting one of the active noise reduction minimum unit modules as the main module, and other active noise reduction minimum unit modules as slave modules. The main module receives the noise signals collected by all slave modules, generates a noise reduction coefficient by combining the noise signals collected by the main module, and sends the noise reduction coefficient to each slave module. Each slave module performs active noise reduction according to the received noise reduction coefficient, and at the same time, the main module performs active noise reduction according to the noise reduction coefficient;

[0038] The cluster working mode is: dividing all the active noise reduction minimum unit modules into one or more groups, with at least one active noise reduction minimum unit module in each group, and the active noise reduction minimum unit modules in each group adopt the centralized working mode;

[0039] The decentralized working mode is: each active noise reduction minimum unit module generates a noise reduction coefficient according to the noise signal collected by itself and performs active noise reduction based on the noise reduction coefficient.

[0040] Preferably, combining multiple active noise reduction minimum unit modules to be set in a centralized, cluster or decentralized manner includes:

[0041] Collecting the real noise signal of the pipeline to be noise-reduced;

[0042] Generate pseudo-noise reduction schemes that conform to centralized, clustered, and decentralized types for multiple active noise reduction minimum unit modules set;

[0043] Conduct active noise reduction simulation in a simulation environment according to the real noise signal and the pseudo-noise reduction scheme, and select the pseudo-noise reduction scheme with the best noise reduction effect according to the simulation result as the finally combined noise reduction scheme.

[0044] Preferably, the active noise reduction minimum unit module includes a microphone, an actuator, and a processor, and the spacing of the active noise reduction minimum unit modules is the spacing of the actuators.

[0045] Second aspect: Provide a modular active noise reduction system, including:

[0046] A maximum frequency determination module, configured to extract the maximum frequency in the noise frequency band to be reduced;

[0047] A cut-off frequency determination module, configured to calculate the cut-off frequency of the pipeline to be reduced;

[0048] A spacing determination module, configured to take the larger one of the maximum frequency and the cut-off frequency as the decision frequency, and determine the spacing of the active noise reduction minimum unit modules according to the decision frequency;

[0049] A number determination module, configured to determine the number of active noise reduction minimum unit modules to be set in the pipeline to be reduced based on the length of the pipeline to be reduced and the determined spacing of the active noise reduction minimum unit modules;

[0050] A combination and implementation module, configured to combine multiple active noise reduction minimum unit modules to be set in a centralized, clustered, or decentralized manner, and arrange them in the pipeline to be reduced after combination to perform active noise reduction on the noise frequency band to be reduced.

[0051] The modular active noise reduction method and system provided by the present invention, compared with the prior art, have the following

[0052] Beneficial effects:

[0053] 1. Modularize active noise reduction, divide it into different minimum units, and realize the active noise reduction of ventilation pipeline equipment of different sizes through combined splicing, reducing the development workload;

[0054] 2. Different from the existing solutions that divide product series according to scenarios, the present invention divides series products according to different technical performances. Users can configure modular active noise reduction units by themselves according to the frequency band and effect they want to reduce noise, and implement the active noise reduction of the equipment, which is flexible and convenient;

[0055] 3. This solution can break through the limitation of relying on pre-installation in the original solution. The product corresponding to this solution can be directly applied to the C-end market, enabling end-users to install it themselves for retrofitting existing equipment in the stock market.

[0056] 4. This technical solution is also applicable to noise reduction scenarios such as integrated stoves, range hoods, and vehicle-mounted air conditioners. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 It is a schematic structural diagram of an embodiment of the active noise reduction minimum unit module of the present invention;

[0058] Figure 2 It is a flowchart of a modular active noise reduction method of the present invention;

[0059] Figure 3 It is a schematic diagram of an embodiment of the centralized architecture of the present invention;

[0060] Figure 4 It is a schematic diagram of an embodiment of the cluster architecture of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0061] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0062] It should be noted that when a component is referred to as being "connected" to another component, it can be directly connected to the other component or there may also be an intermediate component; when a component is referred to as being "fixed" to another component, it can be directly fixed to the other component or there may also be an intermediate component.

[0063] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present invention belongs. The terms used in the description of the present invention in this specification are only for the purpose of describing specific embodiments, and are not intended to limit the present invention.

[0064] The present invention designs a modular active noise reduction unit for ventilation equipment with different pipe sizes and different noise sources. First, the noise frequency band to be controlled is determined, then the number of active noise reduction minimum unit modules is determined according to the pipe size and the noise reduction frequency band, and finally, different module combinations are used to adapt to the target application scenario, completing the rapid adaptation of active noise reduction, shortening the development cycle, and realizing product standardization.

[0065] In the modular design of this embodiment, the minimum active noise cancellation unit module adopted includes a microphone, an actuator, and a processor. It is easy to understand that, in order to support the operation of components, the minimum active noise cancellation unit module also includes necessary peripherals and additional fixing structures, etc. This embodiment provides a structure of the minimum active noise cancellation unit module as Figure 1 shown. Among them, component 1 is the microphone for active noise cancellation, component 2 is the actuator (such as a speaker) for active noise cancellation and the processor for active noise cancellation, component 3 is the circuit connection line, and component 4 is the fixing bracket. For the convenience of the structure of each part, the schematic diagram is enlarged for display. In the actual product design, the integration degree of the structure does not affect the protection of the solution.

[0066] Component 1 and component 2 are fixed on the structural member through component 4 and are connected to the processor through signal lines. The processor can be placed on the structural member where the actuator is located. Component 3 is used for the routing (groove) of the connection line of the electrical circuit signal, and at the same time, electrical interface connectors and structural connectors are reserved for forming an expansion with other minimum active noise cancellation units to construct a cluster-type active noise cancellation architecture. This embodiment adopts the method of combining and expanding with the minimum active noise cancellation module; users can configure the modular active noise cancellation unit by themselves to flexibly adjust the frequency band of the required noise cancellation.

[0067] As Figure 2 shown, a modular active noise cancellation method provided by this embodiment includes the following steps:

[0068] Step 1: Extract the maximum frequency in the noise frequency band to be cancelled.

[0069] For the noise frequency band to be cancelled, the noise frequency band can be directly set as the noise frequency band to be cancelled. It is also possible to collect the noise signal in the duct of the duct-type ventilation equipment using a sensor / microphone, perform spectral energy analysis on the noise signal, and determine the frequency band where the main energy of the noise signal is concentrated as the noise frequency band to be cancelled.

[0070] For example, the method for analyzing the frequency band where the main energy is concentrated in this embodiment is as follows: perform spectral conversion on the noise signal collected in the duct, make different uniform divisions of the entire frequency band, calculate the percentage of the energy of each frequency band in the total energy, select the frequency band with an energy ratio higher than 90% and below 1 kHz as the main energy band. And take the maximum frequency in the main energy band as the maximum frequency.

[0071] Step 2: Measure the size of the ventilation duct opening, and combine with the maximum frequency of the noise cancellation frequency band to determine the number of minimum active noise cancellation unit modules.

[0072] Step 2.1: Calculate the cut-off frequency of the duct to be cancelled.

[0073] According to the theory of acoustic waveguide management, when a sound source is placed inside a pipeline, the sound waves it radiates form specific standing waves at the pipeline boundary, propagate as one-dimensional plane waves in the pipeline direction, and the frequency of the propagating sound waves is lower than the cut-off frequency of the pipeline. Active noise reduction technology usually only targets the sound waves radiating in the pipeline direction. The cut-off frequency of a rectangular pipeline is related to its side lengths, that is:

[0074]

[0075] In the formula, f c represents the cut-off frequency, v represents the sound wave propagation speed, l x and l y respectively represent the length and width of the cross-section of the rectangular pipeline to be noise-reduced. If l x > l y , then n x = 1, n y = 0; otherwise n x = 0, n y = 1.

[0076] And the cut-off frequency of a circular pipeline is related to its radius, that is:

[0077]

[0078] In the formula, r represents the radius of the circular pipeline to be noise-reduced. Ventilation pipelines are generally rectangular. By measuring the longer side of the ventilation pipeline opening, the cut-off frequency of the pipeline can be determined.

[0079] Step 2.2: Take the larger one of the maximum frequency and the cut-off frequency as the decision frequency, and determine the spacing of the minimum active noise reduction unit module according to the decision frequency.

[0080] Since the spacing of the actuators in the active noise reduction system determines the upper limit of the controllable frequency band of active noise reduction, in this embodiment, both the maximum frequency and the cut-off frequency are considered to set the spacing. Generally speaking, the spacing of the minimum active noise reduction unit module is determined by the larger one of the pipeline cut-off frequency and the maximum frequency of the noise reduction frequency band.

[0081] After determining the decision frequency, this spacing is usually set to half of the wavelength of the decision frequency. Therefore, further calculate the wavelength of the decision frequency as follows:

[0082]

[0083] In the formula, λ represents the wavelength, v represents the sound wave propagation speed, v = (331.4 + 0.607T), T represents the Celsius temperature of the pipeline environment, and f represents the decision frequency. If the decision frequency is 1 kHz, under the condition of 25 °C, its wavelength λ = (331.4 + 0.607 * 25) / 1000 = 0.347 m.

[0084] Step 2.3: Determine the number of active noise reduction minimum unit modules to be set in the pipeline to be noise-reduced based on the length of the pipeline to be noise-reduced and the spacing of the determined active noise reduction minimum unit modules.

[0085] In this embodiment, the length of the pipeline to be noise-reduced is divided by the spacing of the determined active noise reduction minimum unit modules to obtain a direct number; then, the direct number is rounded up or down to obtain the number of active noise reduction minimum unit modules to be set. Rounding up has a better noise reduction effect but may affect the ventilation of the pipeline; rounding down does not affect the ventilation of the pipeline, but the noise reduction effect may be slightly weaker than rounding up.

[0086] Taking a common household ducted central air conditioner as an example, the long sides of the ventilation duct openings are mostly 50 cm / 70 cm / 90 cm / 110 cm. If the frequency band to be noise-reduced is below 1 kHz, the actuator spacing of the active noise reduction minimum unit module is 17.33 cm (this spacing is determined by the half-wavelength corresponding to the upper limit frequency of the noise reduction frequency band, and the half-wavelength of a 1 kHz signal is 17.33 cm), and 3 / 4 / 5 / 6 active noise reduction minimum units need to be set respectively; if the frequency band to be noise-reduced is below 600 Hz, at this time, the actuator spacing of the active noise reduction minimum unit module is 28.88 cm (this spacing is the half-wavelength of a 600 Hz signal), and 2 / 3 / 3 / 4 active noise reduction minimum units need to be set respectively.

[0087] Step 3: Combine multiple active noise reduction minimum unit modules to be set using a centralized, clustered, or decentralized method, and arrange them in the pipeline to be noise-reduced after combination to perform active noise reduction on the noise frequency band to be noise-reduced.

[0088] In this embodiment, for the target application scenario, the active noise reduction minimum unit modules are combined and adapted to achieve active noise reduction in the current application scenario. After determining the number of active noise reduction minimum units required for different pipelines, according to the target application scenario, different active noise reduction algorithm architectures are adopted, and different active noise reduction control structures are implemented to achieve the best noise reduction in the current application scenario. Among them, the active noise reduction algorithm architectures mainly include centralized, clustered, and decentralized.

[0089] As Figure 3 shown, the centralized architecture means that all active noise reduction minimum units communicate and interact with each other. One of the active noise reduction minimum units is selected as the main module, and the other active noise reduction minimum units are used as slave modules. The processor of the main module is used as the main processor, and the processors of the slave modules are used as slave processors. The main processor receives all microphones in the system as signal inputs, starts the active noise reduction processor, generates a noise reduction coefficient and distributes it to the slave processors. The slave processors drive their corresponding actuators to emit noise reduction sound waves according to the received noise reduction coefficient to achieve noise reduction.

[0090] As Figure 4As shown in the figure, the clustered architecture means that all the minimum active noise reduction units are divided into multiple groups. Each group is a small centralized architecture, which includes at least one minimum active noise reduction unit. Only the minimum active noise reduction units within the group communicate and interact with each other, and there is no communication and interaction between the minimum active noise reduction units in different groups. The main processor of each group receives the microphones in all the minimum active noise reduction units belonging to it as signal inputs, and drives all the actuators belonging to it to reduce noise.

[0091] The decentralized architecture means that the minimum active noise reduction units are independent of each other and there is no mutual communication and data interaction. Each minimum active noise reduction unit only receives the reference microphone and error microphone belonging to it as signal inputs, and drives the actuator belonging to it to reduce noise.

[0092] To facilitate the rapid deployment of the noise reduction systems of different devices and meet the requirements of different noise reduction frequency bands, the clustered scheme architecture is preferred. The clustered noise reduction architecture only needs to splice and combine the minimum active noise reduction units, and select the architecture with the best noise reduction effect to achieve noise control. In addition, by adjusting the grouping method of the groups in the clustered architecture, the decentralized architecture and the centralized architecture can also be realized. To ensure obtaining the optimal noise reduction scheme, in this embodiment, the real noise signal of the pipeline to be noise-reduced is collected; the pseudo-noise reduction schemes conforming to the centralized, clustered, and decentralized types are respectively generated for multiple minimum active noise reduction unit modules to be set; the active noise reduction simulation is carried out according to the real noise signal and the pseudo-noise reduction scheme in the simulation environment, and the pseudo-noise reduction scheme with the best noise reduction effect is selected as the finally combined noise reduction scheme.

[0093] Taking a household duct-type central air conditioner with the long side of the ventilation duct opening being 110 cm as an example, if the frequency band to be noise-reduced is below 600 Hz, according to the previous analysis, 4 minimum active noise reduction units need to be deployed, and these 4 active noise reduction units can be divided into one group (centralized architecture), two groups (1 + 3), three groups (1 + 2 + 1), or 4 groups (1 + 1 + 1 + 1) (decentralized architecture). The information of the minimum units within each group is shared, and all the minimum units are evenly distributed at the duct opening. During the process of implementing active noise reduction, the microphones of each minimum unit in each group collect the air conditioner duct noise signal and send it to the main processor of their respective groups. After receiving the microphone signal, the main processor of each group starts the active noise reduction processor, generates the noise reduction coefficient and issues it to the slave processor, and the slave processor drives its corresponding actuator to emit noise reduction sound waves. Select the grouping method of the group with the best noise reduction effect as the final noise reduction scheme.

[0094] If the frequency band to be noise-reduced is adjusted to below 1000 Hz, only 2 minimum units need to be added on the basis of the original 4 minimum units. All the minimum units are still evenly distributed at the pipe orifice, and then the groups are re-divided. The original group division can also be retained, and the newly added ones can be used as 1 or 2 groups. Similarly, the grouping method with the best noise reduction effect is selected as the final noise reduction solution.

[0095] In another embodiment, a modular active noise reduction system is provided, including:

[0096] A maximum frequency determination module, configured to extract the maximum frequency in the frequency band of the noise to be reduced;

[0097] A cut-off frequency determination module, configured to calculate the cut-off frequency of the pipe to be noise-reduced;

[0098] A spacing determination module, configured to take the larger one of the maximum frequency and the cut-off frequency as the decision frequency, and determine the spacing of the active noise reduction minimum unit module according to the decision frequency;

[0099] A quantity determination module, configured to determine the number of active noise reduction minimum unit modules to be arranged in the pipe to be noise-reduced based on the length of the pipe to be noise-reduced and the determined spacing of the active noise reduction minimum unit module;

[0100] A combination and implementation module, configured to combine multiple active noise reduction minimum unit modules to be arranged in a centralized, clustered or decentralized manner, and after combination, arrange them in the pipe to be noise-reduced to perform active noise reduction on the frequency band of the noise to be reduced.

[0101] It should be noted that the above modules can be computer program modules, pure hardware modules, or a combination of computer program modules and hardware modules. And the specific limitations on the modular active noise reduction system can refer to the limitations on the modular active noise reduction method in the above text, which will not be elaborated here.

[0102] If it is completed by instructing relevant hardware through a computer program, the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above various methods. Among them, any reference to a memory, storage, database or other medium used in this embodiment can include non-volatile and / or volatile memories. Non-volatile memory can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM) or flash memory. Volatile memory can include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in many forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDR SDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), Rambus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and Rambus dynamic RAM (RDRAM), etc.

[0103] It should be understood that although Figure 2 the steps in the flowchart of Figure 2 are shown in sequence according to the indication of the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless there is a clear indication in this article, the execution of these steps has no strict order limit, and these steps can be executed in other orders. Moreover,

[0104] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0105] The above-described embodiments only represent several implementation manners of the present invention. Their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the appended claims.

Claims

1. A modular active noise reduction method, characterized in that, The modular active noise reduction method includes: Extracting the maximum frequency in the noise frequency band to be reduced; Calculating the cut-off frequency of the pipeline to be reduced; Taking the larger one of the maximum frequency and the cut-off frequency as the decision frequency, and determining the spacing of the minimum unit modules of active noise reduction according to the decision frequency; Based on the length of the pipeline to be reduced and the determined spacing of the minimum unit modules of active noise reduction, determining the number of minimum unit modules of active noise reduction to be set in the pipeline to be reduced; Adopting a centralized, cluster or decentralized method to combine multiple minimum unit modules of active noise reduction to be set, and arranging them in the pipeline to be reduced after combination to perform active noise reduction on the noise frequency band to be reduced.

2. The modular active noise reduction method according to claim 1, wherein The determination method of the noise frequency band to be reduced is as follows: Directly setting the noise frequency band as the noise frequency band to be reduced; Or, collecting the noise signal in the pipeline, performing spectral energy analysis on the noise signal, and determining the frequency band where the main energy of the noise signal is concentrated as the noise frequency band to be reduced.

3. The modular active noise reduction method according to claim 1, wherein, The calculation of the cut-off frequency of the pipeline to be reduced includes: For a rectangular pipeline to be reduced, the cut-off frequency is calculated as follows: Where f c represents the cut-off frequency, v represents the sound wave propagation speed, l x and l y respectively represent the length and width of the cross-section of the rectangular pipeline to be noise-reduced. If l x > l y , then n x = 1, n y = 0; otherwise n x = 0, n y = 1; For a circular pipeline to be reduced, the cut-off frequency is calculated as follows: In the formula, r represents the radius of the circular pipeline to be reduced.

4. The modular active noise reduction method according to claim 1, wherein The determination of the spacing of the minimum unit modules of active noise reduction according to the decision frequency includes: Calculating the wavelength of the decision frequency as follows: In the formula, λ represents the wavelength, v represents the sound wave propagation speed, and f represents the decision frequency; Taking half of the wavelength as the spacing of the minimum unit modules of active noise reduction.

5. The modular active noise reduction method according to claim 1, wherein The determination of the number of minimum unit modules of active noise reduction to be set in the pipeline to be reduced based on the length of the pipeline to be reduced and the determined spacing of the minimum unit modules of active noise reduction includes: Dividing the length of the pipeline to be reduced by the determined spacing of the minimum unit modules of active noise reduction to obtain the direct number; Rounding up or down the direct number as the number of minimum unit modules of active noise reduction to be set.

6. The modular active noise reduction method according to claim 1, characterized in that, The centralized working mode is: selecting one of the minimum unit modules of active noise reduction as the main module, and other minimum unit modules of active noise reduction as slave modules. The main module receives the noise signals collected by all slave modules, generates a noise reduction coefficient by combining the noise signals collected by the main module, and sends the noise reduction coefficient to each slave module. Each slave module performs active noise reduction according to the received noise reduction coefficient, and at the same time, the main module performs active noise reduction according to the noise reduction coefficient; The cluster working mode is: dividing all minimum unit modules of active noise reduction into one or more groups, with at least one minimum unit module of active noise reduction in each group, and the minimum unit modules of active noise reduction in each group adopt the centralized working mode; The decentralized working mode is: each minimum unit module of active noise reduction generates a noise reduction coefficient according to the noise signal collected by itself, and performs active noise reduction based on the noise reduction coefficient.

7. The modular active noise reduction method according to claim 1, wherein, The adoption of a centralized, cluster or decentralized method to combine multiple minimum unit modules of active noise reduction to be set includes: Collecting the real noise signal of the pipeline to be reduced; Generating quasi-noise reduction schemes that conform to the centralized, cluster and decentralized methods for the multiple minimum unit modules of active noise reduction to be set respectively; In the simulation environment, active noise reduction simulation is carried out according to the real noise signal and the proposed noise reduction scheme. The proposed noise reduction scheme with the best noise reduction effect is selected according to the simulation results as the finally combined noise reduction scheme.

8. The modular active noise reduction method according to claim 1, characterized in that, The active noise reduction minimum unit module includes a microphone, an actuator and a processor, and the spacing of the active noise reduction minimum unit module is the spacing of the actuator.

9. A modular active noise reduction system, characterized in that, The modular active noise reduction system includes: A maximum frequency determination module, configured to extract the maximum frequency in the noise frequency band to be noise-reduced; A cut-off frequency determination module, configured to calculate the cut-off frequency of the pipeline to be noise-reduced; A spacing determination module, configured to take the larger one of the maximum frequency and the cut-off frequency as the decision frequency, and determine the spacing of the active noise reduction minimum unit module according to the decision frequency; A number determination module, configured to determine the number of active noise reduction minimum unit modules to be arranged in the pipeline to be noise-reduced based on the length of the pipeline to be noise-reduced and the determined spacing of the active noise reduction minimum unit module; A combination and implementation module, configured to combine multiple active noise reduction minimum unit modules to be arranged in a centralized, clustered or decentralized manner, and arrange them in the pipeline to be noise-reduced after combination to perform active noise reduction on the noise frequency band to be noise-reduced.

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