Noise reduction device, noise reduction unit thereof, and control method

Abstract

The application discloses a noise reduction unit, which comprises a magneto-rheological noise reduction layer, an enclosed shell filled with magneto-rheological fluid, an iron core wrapped outside the enclosed shell, and a conductive coil wound outside the iron core, and an upper substrate and a lower substrate arranged on the upper and lower sides of the magneto-rheological noise reduction layer respectively. The application also discloses a noise reduction unit and a control method. The noise reduction unit has simple structure, strong versatility, and is suitable for standardization and mass production. The noise reduction unit can be conveniently adjusted according to the shape of the noise reduction target, the environment and other factors. The magneto-rheological noise reduction layer has good sound insulation and noise reduction effect on the wide frequency band and the high noise of the medium and low frequency of the industrial complex environment noise spectrum, and can adjust the noise reduction performance in real time according to the change of the noise spectrum characteristics caused by the production conditions switching and the like, so as to effectively reduce the noise exposure level of workers and effectively reduce the occupational health damage caused by high noise.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of industrial noise control, and particularly relates to a noise reduction device, a noise reduction unit thereof and a control method. BACKGROUND

[0002] Noise is a common hazard factor of occupational hearing impairment, and long-term exposure to high noise can cause noise-induced hearing loss. There are various types of high-noise equipment on the site of a chemical enterprise, and the noise spectrum characteristics are different, and they change dynamically with the adjustment of process parameters, which seriously affects the occupational health of workers. In the process of industrial noise hazard control, the following problems exist:

[0003] (1) The noise spectrum characteristics on the site of a chemical industry are very complex, and the conventional noise reduction treatment effect of middle and high frequency noise is significant, but the noise control of low frequency noise is more difficult. The control scheme is often "one point one strategy", which is difficult to implement and cannot be replicated and promoted in large quantities;

[0004] (2) Most chemical equipment needs to switch production conditions, and different production loads cause changes in noise spectrum characteristics. The noise reduction characteristics of noise reduction equipment or materials cannot be adjusted in real time, and cannot meet the noise reduction requirements.

[0005] The information disclosed in this BACKGROUND section is only for the purpose of increasing the understanding of the background of the present application and should not be regarded as an acknowledgment or any form of suggestion that this information forms prior art that is publicly known. SUMMARY

[0006] One of the objects of the present application is to provide a noise reduction device, a noise reduction unit thereof and a control method, thereby improving the problem that the noise control on the site of a chemical industry in the prior art is difficult and cannot be replicated and promoted.

[0007] Another object of the present application is to provide a noise reduction device, a noise reduction unit thereof and a control method, thereby improving the problem that the noise reduction equipment in the prior art has a narrow application range and cannot meet the requirements of production condition changes.

[0008] To achieve the above object, according to a first aspect of the present application, a noise reduction unit is provided, which comprises: a magneto-rheological noise reduction layer, which comprises: a closed shell filled with magneto-rheological fluid; an iron core wrapped outside the closed shell; and a conductive coil wound outside the iron core; and an upper substrate and a lower substrate respectively arranged on the upper and lower sides of the magneto-rheological noise reduction layer.

[0009] Further, in the above technical solution, the magneto-rheological fluid is composed of carrier liquid, magnetic particles and additives.

[0010] Further, in the above technical solution, the carrier liquid is silicone oil or mineral oil; the material of the magnetic particles is iron, cobalt, iron-cobalt alloy or nickel-iron alloy; and the additive is a surfactant.

[0011] Further, in the technical solution, the additive is oleic acid.

[0012] Further, in the technical solution, the volume fraction of the magnetic particles in the magneto-rheological fluid is 30-45%, the response time is 50-70 ms, and the working temperature range is 0-100 DEG C.

[0013] Further, in the technical solution, the thickness of the magneto-rheological fluid is 15-25 mm, and the wall thickness of the closed shell is 0.5-1 mm.

[0014] Further, in the technical solution, the upper substrate and the lower substrate are perforated plates, the thickness is 0.4-0.8 mm, the hole diameter is 1.5-4 mm, the perforation rate is 8-18%, and the upper substrate and the lower substrate are aluminum plates or galvanized steel plates; the material of the iron core is ferroferric oxide, iron-nickel alloy or iron-aluminum alloy, and the thickness is 5-10 mm.

[0015] Further, in the technical solution, the noise reduction unit further comprises: an outer noise reduction layer arranged on the outer side of the upper substrate and / or the lower substrate, the outer noise reduction layer comprises, from inside to outside, a coating layer, a sound absorption layer and a sound insulation layer, and the outer noise reduction layer.

[0016] Further, in the technical solution, the coating layer is non-woven fabric or glass fiber cloth, the thickness of the coating layer is 0.2-0.4 mm, and the area density is 45-65 g / m 2 .

[0017] Further, in the technical solution, the sound absorption layer is made of porous sound absorption material; the sound absorption coefficient is greater than or equal to 0.6; and the thickness of the sound absorption layer is 50-80 mm.

[0018] Further, in the technical solution, the porous sound absorption material is rock wool, slag wool, ultra-fine glass wool, polyurethane or ethyl carbamate.

[0019] Further, in the technical solution, the sound insulation layer is an aluminum plastic plate, and the thickness is 0.4-1.0 mm.

[0020] According to the second aspect of the present application, the present application provides a noise reduction device, comprising: a body made of the noise reduction unit according to any one of the above technical solutions; an excitation power supply connected to both ends of the conductive coil of the noise reduction unit; a magnetometer for detecting the magnetic field strength between the iron core and the closed shell; and a controller in communication connection with the excitation power supply and the magnetometer.

[0021] According to the third aspect of the present application, the present application provides a control method for the noise reduction device according to any one of the above technical solutions, comprising the step of: adjusting the excitation current value output by the excitation power supply according to the noise spectrum of the target to be noise-reduced, the noise reduction requirement and the noise evaluation curve.

[0022] Further, in the technical solution, the control method further comprises the steps of: establishing a high-noise spectrum database of the target to be noise-reduced under different working conditions, and adjusting the excitation current value output by the excitation power supply according to the working condition of the target to be noise-reduced.

[0023] Further, in the technical solution, the control method further comprises: determining the required magnetic field strength value according to the noise spectrum of the target to be noise-reduced, the noise reduction requirement, and the noise evaluation curve, and adjusting the excitation current value output by the excitation power supply when the magnetic field strength measured by the magnetometer is different from the required magnetic field strength value, so that the magnetic field strength measured by the magnetometer is equal to the required magnetic field strength value.

[0024] Compared with the prior art, the present application has one or more of the following beneficial effects:

[0025] 1. The noise reduction unit of the present application has simple structure and strong universality, and is suitable for standardization and mass production. It can be easily adjusted according to the shape of the noise reduction target, environment, etc.

[0026] 2. The present application has good sound insulation and noise reduction effect on the wide frequency band and low frequency high noise of industrial complex environment noise spectrum, and can adjust the noise reduction performance in real time according to the change of noise spectrum characteristics caused by production working condition switching, etc., so as to effectively reduce the noise exposure level of workers and effectively reduce the occupational health damage caused by high noise.

[0027] 3. Traditional sound absorption and insulation materials have little effect on industrial complex environment noise, or the wrapping material is too thick and heavy, affecting the load bearing of the pipeline. The magnetorheological fluid used in the present application is a controllable damping material, which presents the characteristics of low viscosity Newtonian fluid under zero magnetic field, and turns into viscoelastic solid under the action of magnetic field. When the magnetorheological fluid changes from liquid to viscoelastic solid under the action of magnetic field, its damping characteristics convert mechanical vibration and acoustic vibration energy into heat energy and dissipate it, thereby achieving noise reduction effect. The magnetorheological fluid has good reversibility, large damping force, less energy loss, fast response speed and other advantages. Different excitation currents produce different magnetic field strengths, and the damping parameters of the magnetorheological fluid change differently, so it has good blocking performance for noise with different spectrum characteristics.

[0028] 4. When multiple working conditions are stable, the high noise spectrum characteristics under each working condition can be collected, and when the working condition is switched, the excitation current and magnetic field strength of the noise reduction device of the present application can be adjusted according to the database data to block the corresponding spectrum noise intensity.

[0029] 5. The noise reduction unit of the present application is also provided with an outer noise reduction layer with a thickness of 50-80mm, which can effectively reduce the noise intensity in the 1000-5000Hz middle-high frequency band.

[0030] The above description is only a summary of the technical solutions of the present application. In order to make the technical means of the present application clearer and can be implemented according to the content of the specification, and at the same time, the above and other purposes, technical features and advantages of the present application are easier to understand, one or more preferred embodiments are listed below and are described in detail as follows with reference to the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 is a longitudinal sectional view of a noise reduction device according to an embodiment of the present application.

[0032] Figure 2 is a top view of a magnetorheological noise reduction layer according to an embodiment of the present application, wherein the upper substrate is not shown.

[0033] MAIN REFERENCE NUMERALS EXPLANATION:

[0034] 10 - noise reduction unit, 11 - magnetorheological fluid, 12 - closed housing, 13 - iron core, 14 - electrically conductive coil, 21 - upper substrate, 22 - lower substrate, 30 - outer noise reduction layer, 40 - excitation power supply, 41 - power switch, 42 - power regulator, 50 - magnetometer. DETAILED DESCRIPTION

[0035] The specific embodiments of the present application are described in detail below with reference to the accompanying drawings, but it should be understood that the scope of protection of the present application is not limited by the specific embodiments.

[0036] Unless otherwise clearly indicated, throughout the specification and claims, the term "comprise" or variations such as "comprises" or "comprising" will be understood to imply the inclusion of a stated element or group of elements but not the exclusion of any other element or group of elements.

[0037] In this document, spatially relative terms, such as "beneath", "below", "lower", "above", "upper", and the like, can be used to describe one element's or feature's relationship to another element or feature as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientations depicted in the figures. For example, if a device is inverted in the figure, a spatially relative term such as "below" or "beneath" can indicate, for example, that an element or feature is located in the above direction with respect to another element or feature, rather than in the below direction, which was depicted in the figures. The exemplary term "below" can therefore encompass both below and above orientations. Other terms such as "up", "down", "front", "back", "side", "end", "vertical", "horizontal", "top", "bottom", "under", "above", "underneath", "on", "above", "next", etc. can be interpreted in the same manner. The terms "first", "second", "third", etc. can be interpreted as "first", "second", "third", etc. in the sense of priority, and not necessarily in the sense of spatial or chronological order.

[0038] In this document, the terms "first," "second," etc., are used to distinguish two different elements or parts, and are not used to define specific positions or relative relationships. In other words, in some embodiments, the terms "first," "second," etc., can also be used interchangeably.

[0039] like Figure 1 and Figure 2 As shown, the noise reduction unit 10 according to a specific embodiment of the present invention includes a magnetorheological noise reduction layer. In the magnetorheological noise reduction layer, a magnetorheological fluid 11 is stored in a closed shell 12, and an iron core 13 suitable for the workplace is wrapped around the closed shell 12. A conductive coil 14 is wound around the iron core 13 to form an electromagnet. An upper substrate 21 and a lower substrate 22 are respectively provided on the upper and lower sides of the magnetorheological noise reduction layer.

[0040] Further, in one or more exemplary embodiments of the present invention, the magnetorheological fluid 11 is composed of a carrier liquid, magnetic particles, and additives. Exemplarily, but not limitingly, the carrier liquid can be silicone oil or mineral oil; the material of the magnetic particles can be iron powder, cobalt powder, iron-cobalt alloy, or nickel-iron alloy, etc.; the additives can be surfactants such as oleic acid. Further, in one or more exemplary embodiments of the present invention, the volume fraction of magnetic particles in the magnetorheological fluid 11 is 30-45%, the response time is 50-70 ms, and the operating temperature range is 0-100°C. Exemplarily, the thickness of the magnetorheological fluid 11 is 15-25 mm, and the wall thickness of the enclosed shell 12 is 0.5-1 mm.

[0041] Furthermore, in one or more exemplary embodiments of the present invention, the upper substrate 21 and the lower substrate 22 are micro-perforated plates, such as perforated metal plates like aluminum plates or galvanized steel plates. The thickness of the upper substrate 21 and the lower substrate 22 can be 0.4–0.8 mm, the hole diameter is 1.5–4 mm, and the perforation rate is 8–18%. Perforation patterns include rectangular holes, square holes, diamond holes, round holes, oblong holes, hexagonal holes, cross holes, triangular holes, slotted holes, plum blossom holes, fish scale holes, patterned holes, herringbone mesh, chevron holes, pentagonal star holes, irregular holes, embossed holes, special-shaped holes, louvered holes, etc., and the present invention is not limited thereto. Furthermore, in one or more exemplary embodiments of the present invention, the iron core 13 can be made of iron(III) oxide, iron-nickel alloy, or iron-aluminum alloy, and its thickness can be 5–10 mm.

[0042] Furthermore, in one or more exemplary embodiments of the present invention, the noise reduction unit 10 further includes an outer noise reduction layer 30, which is disposed on the outer side of the upper substrate 21 and / or the lower substrate 22, and the outer noise reduction layer 30 includes, from the inside to the outside, a cover layer, a sound-absorbing layer, and a sound-insulating layer. Figure 1In the shown embodiment, the outer sides of the upper substrate 21 and the lower substrate 22 are provided with the outer noise reduction layer 30. It should be understood that the present application is not limited thereto, and those skilled in the art can make deletions or modifications according to the noise reduction needs.

[0043] Further, in one or more exemplary embodiments of the present application, the coating layer can be a non-woven fabric or a glass cloth, etc., which is attached to the outer side of the upper substrate or the lower substrate. The thickness of the coating layer is 0.2-0.4 mm, and the area density is 45-65 g / m 2 . Further, in one or more exemplary embodiments of the present application, the sound absorption layer can be made of porous sound absorption materials, such as rock wool, slag wool, ultra-fine glass wool, polyurethane or ethyl carbamate, and products thereof, etc. The thickness of the sound absorption layer is greater than or equal to 0.6; the sound absorption material occupies an area of not less than 30% of the sound absorption layer, and the thickness of the sound absorption layer is 50-80 mm. The optimal bulk density parameters of different materials are different, and are generally selected between 24-80 kN / m 3 . Further, in one or more exemplary embodiments of the present application, the sound insulation layer can be an aluminum plastic plate with a thickness of 0.4-1.0 mm.

[0044] Reference Figure 1 As shown, the noise reduction device according to the specific embodiment of the present application comprises a body made of the noise reduction unit 10. The two ends of the conductive coil 14 of the noise reduction unit 10 are connected with the excitation power supply 40. Exemplarily, a power switch 41 and a power regulator 42 are arranged on the line between the conductive coil 14 and the excitation power supply 40. The magnetometer 50 is used for detecting the magnetic field strength, and the magnetic field probe is placed perpendicular to the magnetic field direction, and can be arranged between the iron core 13 and the closed shell 12. The noise reduction device of the present application is provided with a controller (not shown in the figure), which is in communication connection with the excitation power supply 40 and the magnetometer 50, thereby playing a control and adjustment role.

[0045] The control method for the noise reduction device according to the specific embodiment of the present application for any one of the above technical solutions comprises the step of adjusting the excitation current value output by the excitation power supply according to the noise spectrum of the target to be noise-reduced, the noise reduction requirement and the noise evaluation curve.

[0046] Further, in one or more exemplary embodiments of the present application, the control method further comprises the step of establishing a high-noise spectrum database under different working conditions of the target to be noise-reduced, and adjusting the excitation current value output by the excitation power supply according to the working condition of the target to be noise-reduced.

[0047] Further, in one or more exemplary embodiments of the present application, the control method further comprises: determining a required magnetic field strength value according to the noise spectrum of the target to be noise-reduced, the noise reduction requirement and the noise evaluation curve, and adjusting the excitation current value output by the excitation power supply to make the magnetic field strength measured by the magnetometer equal to the required magnetic field strength value when the magnetic field strength measured by the magnetometer is different from the required magnetic field strength value.

[0048] The present application will be described in more detail below with reference to specific embodiments, but the present application is not limited thereto.

[0049] Embodiment 1

[0050] This embodiment uses the noise reduction device of the present application (as shown in Figure 1 ) to reduce the noise of a high-noise equipment pipeline. The noise spectrum of the high-noise equipment pipeline presents the characteristics of wide frequency band, prominent medium and low frequency, and high intensity, and the effect of traditional sound absorption and insulation is not significant, or the thickness and weight of the wrapping material are too large to affect the load bearing of the pipeline.

[0051] The noise reduction device of this embodiment does not need a skeleton for installation, and only needs to be fixed to the outer surface of the high-noise equipment pipeline in a corresponding shape, for example, by clamping, buckling or the like. When the excitation current is 0.5-3A, the magnetic field strength is 50-350mT (50mT, 100mT, 150mT, 200mT, 250mT, 300mT, 350mT), which can effectively block the medium and low frequency noise of 50-2000Hz, and the overall sound insulation amount is 15-30dB, and the data corresponding relationship in the range forms a magneto-rheological technology parameter database. Generally, adjusting the excitation current to a corresponding value can achieve the required noise reduction effect, but sometimes the magnetic field strength actually obtained by the excitation current (i.e. the magnetic field strength measured by the magnetometer) does not conform to the corresponding relationship, at which time the excitation current needs to be continuously adjusted until the magnetic field strength measured by the magnetometer meets the requirements in the magneto-rheological technology parameter database, so as to achieve the corresponding noise reduction effect.

[0052] According to the spectral characteristics of the high-noise equipment pipeline, the power switch 41 is turned on, the power regulator 42 is adjusted to generate a suitable excitation current, and the reading of the magnetometer 50 is observed at the same time to ensure that the magnetic field strength meets the requirements. When the magneto-rheological fluid 11 is converted from a liquid to a viscoelastic solid under the action of the magnetic field, its damping characteristics convert the mechanical vibration and acoustic vibration energy into heat energy and dissipate it.

[0053] Embodiment 2

[0054] This embodiment uses the noise reduction device of the present application (as shown in Figure 1 ) to reduce the noise of a high-noise equipment. The noise spectrum of the high-noise equipment presents the characteristics of wide frequency band, prominent medium and low frequency, and high intensity, so it is necessary to install a soundproof cover around the high-noise equipment or a soundproof barrier on the inspection route.

[0055] The noise reduction device of the embodiment can adopt light steel keel as a framework, and fix the noise reduction unit 10 with a corresponding shape on the framework as a module, for example, by fixing through clamping, buckling, hanging, riveting and the like. When there is a special process requirement, such as a detection door and window, a process operation door and window, an instrument reading door and window, a process pipeline or cable penetrating through and the like, a corresponding door and window or hole can be opened on the noise reduction unit 10, but the door and window or hole should be filled with a sealing material to ensure its sealing property and prevent sound leakage. When the excitation current is 0.5-3 A, the magnetic field strength is 50-350 mT, the middle and low frequency noise of 50-2000 Hz can be effectively blocked, and the overall sound insulation amount is 15-30 dB. The data corresponding relationship in the variation range forms a magneto-rheological technology parameter database.

[0056] When put into use, according to the frequency spectrum characteristics of the high-noise equipment, the power switch 41 is turned on, the power regulator 42 is adjusted to generate a suitable excitation current, and the reading of the magnetometer 50 is observed at the same time to ensure that the magnetic field strength meets the requirements. When the magneto-rheological fluid 11 is converted from a liquid to a viscoelastic solid under the action of the magnetic field, the damping property of the magneto-rheological fluid 11 converts the mechanical vibration and acoustic vibration energy into heat energy and dissipates it.

[0057] Embodiment 3

[0058] With the long-period operation of the high-noise equipment, the internal parts are damaged, lubrication is not enough, the position is deviated and the like due to various reasons, which leads to the frequency spectrum characteristics of the high-noise equipment shifting to the middle and low frequencies. The equipment needs to be operated for a long time, and the equipment needs to be overhauled for a long time, so the noise control is difficult. The noise reduction device (refer to Figure 1 ) of the embodiment is attached to the position with large vibration amplitude of the high-noise equipment, the excitation current is adjusted according to the noise frequency spectrum characteristics and vibration frequency, and then the magnetic field strength and the damping property of the magneto-rheological fluid are changed, so that the vibration peak value at a specific frequency can be eliminated, the operation stability of the equipment can be improved, and the middle and low frequency noise intensity of the equipment can be reduced. The vibration energy of the high-noise equipment can be transferred and dissipated, and the resonance can be effectively suppressed.

[0059] The foregoing description of specific exemplary embodiments of the application is intended to be illustrative only. These descriptions are not intended to be limiting to the precise forms disclosed and, indeed, many modifications and variations are possible in light of the above teachings that can be made by those skilled in the art without departing from the spirit and broader scope of the application. It is therefore intended that the disclosure be given broad scope and applications and be constructed to cover any such modifications and any special examples with specificity illustrated by the claims now appended and thereafter appended.

Claims

1. A noise reduction device, characterized by, The body is made of a noise reduction unit. The noise reduction unit comprises a magneto-rheological noise reduction layer, which comprises a closed shell filled with magneto-rheological fluid, an iron core wrapped outside the closed shell, and a conductive coil wound outside the iron core; the noise reduction unit further comprises an upper substrate and a lower substrate respectively arranged on the upper and lower sides of the magneto-rheological noise reduction layer; the noise reduction unit further comprises an outer noise reduction layer arranged outside the upper substrate and / or the lower substrate, which comprises a coating layer, a sound absorption layer and a sound insulation layer from inside to outside; An excitation power source connected to both ends of the conductive coil of the noise reduction unit; A magnetometer for detecting the magnetic field strength between the iron core and the closed shell; and A controller in communication connection with the excitation power source and the magnetometer; The noise reduction device is used for reducing the noise of high-noise equipment pipeline, and the noise spectrum of high-noise equipment pipeline presents the characteristics of wide frequency band, prominent medium and low frequency, and high intensity; the noise reduction device fixes the noise reduction unit of corresponding shape on the outer surface of high-noise equipment pipeline without installing the framework; or The noise reduction device is used for reducing the noise of high-noise equipment, and the noise spectrum of high-noise equipment presents the characteristics of wide frequency band, prominent medium and low frequency, and high intensity; a sound insulation cover is installed around the high-noise equipment or a sound insulation barrier is installed on the inspection route, and the noise reduction device uses light steel keel as the framework and fixes the noise reduction unit of corresponding shape as the module on the framework; or The noise reduction device is used for the case that the spectrum characteristics of high-noise equipment deviate to medium and low frequency due to long-period operation of high-noise equipment, and the noise reduction device attaches the noise reduction unit to the position with larger amplitude of high-noise equipment. The magneto-rheological fluid is composed of carrier liquid, magnetic particles and additives.

2. The noise reducing device of claim 1, wherein, The carrier liquid is silicone oil or mineral oil; the material of the magnetic particles is iron, cobalt, iron-cobalt alloy or nickel-iron alloy; and the additive is a surfactant.

3. The noise reducing device of claim 2, wherein, The additive is oleic acid.

4. The noise reducing device of claim 3, wherein, The volume fraction of the magnetic particles in the magneto-rheological fluid is 30-45%, the response time is 50-70 ms, and the working temperature range is 0-100℃.

5. The noise reducing device of claim 2, wherein, The thickness of the magneto-rheological fluid is 15-25 mm, and the wall thickness of the closed shell is 0.5-1 mm.

6. The noise reducing device of claim 1, wherein, The upper substrate and the lower substrate are perforated plates with a thickness of 0.4-0.8 mm, a pore size of 1.5-4 mm, and a perforation rate of 8-18%, and the upper substrate and the lower substrate are aluminum plates or galvanized steel plates; the material of the iron core is magnetite, iron-nickel alloy or iron-aluminum alloy, and the thickness is 5-10 mm.

7. The noise reducing device of claim 1, wherein, The sound absorption layer is made of porous sound absorption material, and the thickness absorption coefficient is greater than or equal to 0.6; the thickness of the sound absorption layer is 50-80 mm.

8. The noise reducing device of claim 1, wherein, The coating is a non-woven fabric or glass cloth, the thickness of the coating is 0.2-0.4mm, the area density is 45-65g / m 2 .

9. The noise reducing device of claim 1, wherein, The porous sound absorption material is rock wool, slag wool, ultra-fine glass wool, polyurethane or ethyl carbamate.

10. The noise reducing device of claim 9, wherein, The sound insulation layer is an aluminum plastic plate with a thickness of 0.4-1.0 mm.

11. The noise reducing device of claim 1, wherein, The method comprises the following steps:

12. A control method for the noise reduction device according to any one of claims 1 to 11, characterized by, Adjusting the excitation current value output by the excitation power source according to the noise spectrum of the target to be reduced, the noise reduction requirement and the noise evaluation curve. The method further comprises the following steps:

13. The control method according to claim 12, characterized by, ​ A high-noise spectrum database of the target to be de-noised under different working conditions is established, and the excitation current value output by the excitation power supply is adjusted according to the working condition of the target to be de-noised.

14. The control method according to claim 12, characterized by, Also includes: According to the noise spectrum of the target to be de-noised, the noise reduction requirement and the noise evaluation curve, the required magnetic field strength value for noise reduction is determined, and when the magnetic field strength measured by the magnetic field strength meter is different from the required magnetic field strength value, the excitation current value output by the excitation power supply is adjusted to make the magnetic field strength measured by the magnetic field strength meter equal to the required magnetic field strength value.

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