CN110571050A - capacitor and mass determination method for mass resonator plate - Google Patents

capacitor and mass determination method for mass resonator plate Download PDF

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Publication number
CN110571050A
CN110571050A CN201910979993.4A CN201910979993A CN110571050A CN 110571050 A CN110571050 A CN 110571050A CN 201910979993 A CN201910979993 A CN 201910979993A CN 110571050 A CN110571050 A CN 110571050A
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China
Prior art keywords
capacitor
mass
frequency
plate
distance
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CN201910979993.4A
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Inventor
祝令瑜
汲胜昌
李金宇
高璐
姜智桐
杨航
党永亮
张壮壮
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China Electric Power Research Institute Co Ltd CEPRI
Xian Jiaotong University
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Xian Jiaotong University
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Priority to CN201910979993.4A priority Critical patent/CN110571050A/en
Publication of CN110571050A publication Critical patent/CN110571050A/en
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B5/00—Measuring arrangements characterised by the use of mechanical techniques
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B5/00—Measuring arrangements characterised by the use of mechanical techniques
    • G01B5/30—Measuring arrangements characterised by the use of mechanical techniques for measuring the deformation in a solid, e.g. mechanical strain gauge
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01G—WEIGHING
    • G01G19/00—Weighing apparatus or methods adapted for special purposes not provided for in the preceding groups
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01H—MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES
    • G01H17/00—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves, not provided for in the preceding groups
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R23/00—Arrangements for measuring frequencies; Arrangements for analysing frequency spectra
    • G01R23/02—Arrangements for measuring frequency, e.g. pulse repetition rate; Arrangements for measuring period of current or voltage
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G4/00—Fixed capacitors; Processes of their manufacture
    • H01G4/002—Details
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G4/00—Fixed capacitors; Processes of their manufacture
    • H01G4/002—Details
    • H01G4/224—Housing; Encapsulation
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G4/00—Fixed capacitors; Processes of their manufacture
    • H01G4/32—Wound capacitors
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G4/00—Fixed capacitors; Processes of their manufacture
    • H01G4/38—Multiple capacitors, i.e. structural combinations of fixed capacitors

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Manufacturing & Machinery (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Measurement Of Mechanical Vibrations Or Ultrasonic Waves (AREA)

Abstract

The application discloses a quality determination method for a capacitor and a quality resonance plate, and relates to the technical field of power equipment. The capacitor comprises a capacitor shell and a capacitor core arranged in the shell, wherein a mass resonance plate is arranged in the capacitor core, the density of the mass resonance plate is greater than a density threshold value, the distance from the mass resonance plate to one end of the capacitor core is a first distance, the first distance is determined according to the mass of the mass resonance plate, and the mass of the mass resonance plate is determined according to the natural frequency of the capacitor and the electric field force frequency of the capacitor. The capacitor provided by the embodiment of the application can remove the noise of the capacitor, which is reduced by the resonance of the natural frequency of the capacitor and the frequency of the electric field force.

Description

Capacitor and mass determination method for mass resonator plate
Technical Field
The application relates to the technical field of power equipment, in particular to a quality determination method for a capacitor and a quality resonance plate.
Background
capacitors are important devices for power systems and are widely used in various industries. However, the capacitor has a serious noise pollution problem.
In the related art, a method for improving noise pollution of a capacitor includes: the sound-absorbing cavity is arranged in the capacitor core of the capacitor and can absorb incident sound waves, so that the vibration isolation effect is achieved.
However, in the above-described technique, the capacitor core having the sound-absorbing cavity mounted therein is likely to resonate with other components of the capacitor, and thus noise of the capacitor does not decrease or increase.
Disclosure of Invention
In view of this, it is necessary to provide a method for determining the quality of a capacitor and a mass resonator plate, which addresses the above-mentioned problem of noise in the capacitor.
In a first aspect, embodiments of the present application provide a capacitor, where the capacitor includes a capacitor case and a capacitor core installed in the capacitor case, a mass resonance plate is disposed in the capacitor core, a density of the mass resonance plate is greater than a density threshold, a distance from the mass resonance plate to one end of the capacitor core is a first distance, the first distance is determined according to a mass of the mass resonance plate, and the mass of the mass resonance plate is determined according to a natural frequency of the capacitor and an electric field force frequency of the capacitor.
In one embodiment, the first distance satisfies a first formula, which is:
sinkL-kLβsinkL1sink(L-L1)＝0；
wherein the content of the first and second substances,Omega is the angular frequency of the anti-resonance frequency, and the anti-resonance frequency is determined according to the electric field force frequency of the capacitor;The wave velocity, E and rho are elastic modulus and mass density, and the elastic modulus and the mass density are determined according to the natural frequency of the capacitor; l is the envelope length of the capacitor core, L1The first distance is a distance between the first and second electrodes,The non-dimensional parameter of the mass resonance plate is A, the sectional area of the capacitor core is A, and M is the mass of the mass resonance plate.
In one embodiment, the end surfaces of the mass resonance plates parallel to the wide side surfaces of the capacitor are provided with damping grooves.
In one embodiment, the depth of the damping groove is 10-40mm, and the height of the damping groove is 1-5 mm.
In one embodiment, the damping grooves are multiple and arranged at intervals.
In one embodiment, a top acoustic enclosure is mounted to a top surface location of the capacitor, a bottom acoustic enclosure is mounted to a bottom surface location of the capacitor, and plastic foam is disposed within the top acoustic enclosure and/or the bottom acoustic enclosure.
In one embodiment, the mass resonator plate is a solid metal plate.
in a second aspect, an embodiment of the present application provides a method for determining a mass of a mass resonator plate, where the mass resonator plate is disposed in a capacitor core of a capacitor, a density of the mass resonator plate is greater than a density threshold, a distance from the mass resonator plate to one end of the capacitor core is a first distance, the first distance is determined according to a mass of the mass resonator plate, and the mass of the mass resonator plate is determined according to a natural frequency of the capacitor and an electric field force frequency of the capacitor, the method including:
Determining a mechanical characteristic parameter of the capacitor according to the natural frequency of the capacitor;
determining an anti-resonance frequency of the capacitor according to the electric field force frequency of the capacitor;
obtaining the encapsulation length of the capacitor core and the sectional area of the capacitor core;
And calculating the mass of the mass resonance plate according to the mechanical characteristic parameters, the anti-resonance frequency, the packaging length and the sectional area.
In one embodiment, a first distance set is obtained, the first distance set comprises a plurality of first distances, the first distances are distances from the mass resonator plates to one end of the capacitor core, and the first distances are smaller than the envelope length;
Calculating the candidate mass of the mass resonance plate according to the mechanical characteristic parameters, the anti-resonance frequency, the first distance and the sectional area aiming at each first distance;
And selecting the target mass from the candidate masses as the mass of the mass resonance plate.
in one embodiment, the method further comprises: and determining the first distance corresponding to the target mass as the mounting position of the mass resonance plate.
in one embodiment, the mechanical property parameters include modulus of elasticity and mass density.
The beneficial effects brought by the technical scheme provided by the embodiment of the application at least comprise:
the capacitor provided by the embodiment of the application can remove the noise of the capacitor, which is reduced by the resonance of the natural frequency of the capacitor and the frequency of the electric field force. The capacitor comprises a capacitor shell and a capacitor core arranged in the shell, wherein a mass resonance plate is arranged in the capacitor core, the mass resonance plate is a solid metal plate, the distance from the mass resonance plate to one end of the capacitor core is a first distance, the first distance is determined according to the mass of the mass resonance plate, and the mass of the mass resonance plate is determined according to the natural frequency of the capacitor and the electric field force frequency of the capacitor. In the embodiment of the application, the mass resonance plate is arranged in the capacitor core, the mass of the mass resonance plate and the first distance from the mass resonance plate to one end of the capacitor core are determined according to the natural frequency and the electric field force frequency of the capacitor, and the natural frequency of the capacitor can be changed according to the determined first distance and the mass of the mass resonance plate, so that the natural frequency of the capacitor and the electric field force frequency of the capacitor cannot resonate, and the purposes of removing the resonance effect and reducing the noise of the capacitor are achieved.
Drawings
Fig. 1 is a schematic structural diagram of a capacitor according to an embodiment of the present disclosure;
fig. 2 is a flowchart of a method for determining the quality of a quality resonator plate according to an embodiment of the present application;
FIG. 3 is a schematic diagram illustrating the measurement of the elastic modulus of a capacitor core provided in the embodiments of the present application;
Fig. 4 is a flowchart of a mass calculation process of a mass resonance plate according to an embodiment of the present application;
fig. 5 is a schematic structural diagram of a capacitor core according to an embodiment of the present disclosure;
Fig. 6 is a schematic structural diagram of a mass resonator plate according to an embodiment of the present disclosure;
fig. 7 is a schematic diagram of a frequency sweep test provided in an embodiment of the present application;
FIG. 8 is a schematic diagram illustrating a vibration frequency response curve of a capacitor according to an embodiment of the present disclosure;
fig. 9 is a schematic diagram illustrating a comparison of vibration frequency response curves of a capacitor with a mass resonance plate and a capacitor without the mass resonance plate according to an embodiment of the present application;
Fig. 10 is a schematic diagram of sound pressure level distributions of a capacitor with a mass resonator plate and a capacitor without a mass resonator plate under a 1# loading condition provided by an embodiment of the present application;
fig. 11 is a schematic diagram of sound pressure level distributions of a capacitor with a mass resonator plate and a capacitor without a mass resonator plate under a 2# loading condition provided by an embodiment of the present application;
fig. 12 is a flowchart of a method for determining the quality of a quality resonator plate according to an embodiment of the present application.
Detailed Description
To make the objects, technical solutions and advantages of the present application more clear, embodiments of the present application will be described in further detail below with reference to the accompanying drawings.
The converter station is an energy conversion station for converting alternating current into direct current or converting direct current into alternating current in an extra-high voltage direct current transmission system. Important components of the converter station include power capacitors, whose main function is to filter and reactive-load compensate the power system. Along with the high-speed development of the power industry in China, the scale of the converter station is larger and larger, the number of power capacitors used in the converter station is larger and larger, the problem of noise pollution caused by the power capacitors is more prominent, and much interference is brought to residents around the converter station. The reason why the power capacitor generates noise is mainly as follows: under the action of the alternating electric field, the polar plates of the capacitor are subjected to the action of the electric field force to generate vibration, and the vibration is transmitted to the capacitor shell to cause the capacitor shell to vibrate and generate noise to radiate to the periphery.
In the related art, a method for improving noise pollution of a power capacitor includes: install in power capacitor's condenser core and inhale the sound cavity, when the polar plate of condenser received the electric field force effect to produce the vibration, this vibration is incited when inhaling the sound cavity, can be absorbed by inhaling the sound cavity, and the vibration that transmits capacitor case like this weakens for capacitor case's amplitude reduces, thereby reduces the noise.
However, in the above-described technology, when the mechanical natural frequency of the capacitor is the same as or close to the electric field force frequency of the capacitor, the case of the capacitor resonates, and the amplitude of the case of the capacitor increases, thereby increasing the vibration. For noise generated by resonance, the sound absorption cavity has poor sound absorption effect, and noise cannot be effectively reduced. Moreover, researchers find that after long-term use, the sound absorption effect of a part of the sound absorption cavity is obviously attenuated, and after long-term use, impregnant in the power capacitor may permeate into the sound absorption cavity, so that the sound insulation function of the sound absorption cavity is disabled, the noise of the power capacitor cannot be reduced, and the internal impregnation of the power capacitor is insufficient, the insulativity is reduced, and the power capacitor has potential safety hazards.
the capacitor provided by the embodiment of the application can remove the noise of the capacitor, which is reduced by the resonance of the natural frequency of the capacitor and the frequency of the electric field force. The capacitor comprises a capacitor shell and a capacitor core arranged in the shell, wherein a mass resonance plate is arranged in the capacitor core, the mass resonance plate is a solid metal plate, the distance from the mass resonance plate to one end of the capacitor core is a first distance, the first distance is determined according to the mass of the mass resonance plate, and the mass of the mass resonance plate is determined according to the natural frequency of the capacitor and the electric field force frequency of the capacitor. In the embodiment of the application, the mass resonance plate is arranged in the capacitor core, the mass of the mass resonance plate and the first distance from the mass resonance plate to one end of the capacitor core are determined according to the natural frequency and the electric field force frequency of the capacitor, and the natural frequency of the capacitor can be changed according to the determined first distance and the mass of the mass resonance plate, so that the natural frequency of the capacitor and the electric field force frequency of the capacitor cannot resonate, and the purposes of removing the resonance effect and reducing the noise of the capacitor are achieved.
Referring to fig. 1, a schematic structural diagram of a capacitor provided by an embodiment of the present application is shown, where the capacitor includes a capacitor case and a capacitor core installed in the capacitor case, and a mass resonance plate is disposed in the capacitor core, and a density of the mass resonance plate is greater than a density threshold, where a mass of the mass resonance plate is determined according to a natural frequency and an electric field force frequency of the capacitor, and an installation position of the mass resonance plate in the capacitor core is determined according to the mass of the mass resonance plate.
optionally, the basic structure of the capacitor includes a capacitor core 101, an impregnant, a fastener, a lead (not shown in fig. 1), a capacitor case 102, and an outlet sleeve 103, wherein the capacitor core 101 is formed by a plurality of core units 105, the core units 105 are formed by rolling a solid medium with a certain thickness and a certain number of layers and aluminum foil electrodes, and the plurality of core units 105 are combined to form the capacitor core 101. Capacitor core 101 is placed in an impregnant, which can improve dielectric breakdown strength of capacitor core 101 and has an insulating effect. The fastener is used to fix the capacitor element 101. One end of the lead is connected with the capacitor core 101, and the other end is connected with the outgoing line sleeve 103. The outlet sleeve 103 is typically welded to the top of the capacitor case 102. The capacitor case 102 is generally made of stainless steel or aluminum alloy or thin steel plate by welding, and the surface is coated with flame retardant paint.
in the embodiment of the present application, a mass resonance plate 104 is disposed in a capacitor core, and a mass of the mass resonance plate 104 is determined according to a natural frequency and an electric field force frequency of a capacitor, optionally, as shown in fig. 2, a process of determining a mass of the mass resonance plate may include the following steps:
step 201, determining mechanical characteristic parameters of the capacitor according to the natural frequency of the capacitor.
Wherein the natural frequency of the capacitor is the mechanical frequency of the capacitor core before the mass resonance plate is installed. The mechanical characteristic parameters of the capacitor include the elastic modulus E and the mass density ρ. The process of calculating the mechanical characteristic parameters of the capacitor core from the natural frequency of the capacitor may be:
the elastic modulus of the capacitor core is calculated according to formula (1), and formula (1) is as follows:
Wherein E is the elastic modulus of the capacitor core; f is uniform pressure applied on the capacitor core; a is the sectional area of the capacitor core; Δ L is the compression of the capacitor core; l is the envelope length of the capacitor core.
The elastic modulus gives the relation between the acting force and the deformation, the determined uniform distribution pressure F (namely the compression force) is applied to the capacitor core, and the compression amount of the capacitor core is measured at the same time, namely the elastic modulus of the capacitor core can be obtained through the formula (1).
Alternatively, the conventional elastic modulus tester cannot apply a force to the capacitor core immersed in the impregnant. In the embodiment of the present application, to determine the elastic modulus of the capacitor core, as shown in fig. 3, an autotransformer 301 and a high voltage rectifier stack 302 are used to charge a capacitor core 303, a direct current voltage is applied to the capacitor core 303, an electrostatic force is generated to compress the capacitor core 303, and a dial indicator 304 is used to measure the absolute compression amount of the capacitor core 303. When a dc voltage is applied, the capacitor 30 is in a stable state, and the compressive displacement and the electric field force of the capacitor are not coupled as described above, so that the electrostatic force per unit area can be determined according to the dc voltage, and the elastic modulus of the capacitor core can be obtained by combining the measured deformation.
The capacitor core in the test was still immersed in the impregnant, with only the ends thereof exposed. The power frequency voltage can charge the capacitor core through the high-voltage silicon stack, and simultaneously, the deformation quantity of the capacitor core is measured by the dial indicator 304, and the measuring range can be as follows: 0-12.7 mm, resolution is: 0.001 mm.
when the capacitor core is loaded with direct-current voltage, the electric field force on each polar plate in the capacitor core is balanced, and the whole capacitor core only shows end stress. The formula (2) can be obtained by transforming the formula (1) through the relation between the electric field force and the capacitance value of the capacitor:
Wherein: epsilon is the dielectric quantity of the single-layer capacitor; u is loaded direct current voltage; d0the distance between the polar plates of the single-layer capacitor; l is the envelope length of the capacitor core; Δ L is the compression of the capacitor core.
For a certain elastic modulus, the compression amount of the capacitor core is in direct proportion to the square of the loaded direct current voltage, and the elastic modulus can be calculated according to the formula (2) by combining the size and the electrical parameters of the capacitor core.
after the modulus of elasticity of the capacitor core is determined, the mass density of the capacitor can be calculated according to equation (3). The formula (3) is:
in the formula: ρ is the mass density of the capacitor core; e is the modulus of elasticity of the capacitor core; f. of1Is the natural frequency of the capacitor; l is the envelope length of the capacitor core.
step 202, determining an anti-resonance frequency of the capacitor according to the electric field force frequency of the capacitor.
In the embodiment of the present application, the obtaining process of the electric field force frequency of the capacitor includes: the capacitor is loaded with single-frequency voltage, the harmonic frequency loaded by the capacitor under different working conditions is obtained, the corresponding electric field force frequency is calculated according to different harmonic frequencies, and a plurality of electric field force frequencies corresponding to the capacitor can be obtained.
and selecting the electric field force frequency closest to the natural frequency of the capacitor from the plurality of electric field force frequencies as the anti-resonance frequency of the capacitor.
Step 203, obtaining the encapsulation length of the capacitor core and the sectional area of the capacitor core.
the envelope length of the capacitor core is the envelope length before the mass resonator plate is disposed in the capacitor core.
and step 204, calculating the mass of the mass resonance plate according to the mechanical characteristic parameters, the anti-resonance frequency, the packaging length and the sectional area.
alternatively, as shown in fig. 4, the process of calculating the mass of the mass resonance plate from the elastic modulus E and the mass density ρ, the anti-resonance frequency, the envelope length L of the capacitor core, and the sectional area a of the capacitor core may include the steps of:
step 401, a first distance set is obtained.
in the embodiment of the present application, as shown in fig. 5, the distance from the mass resonator plate 502 to one end of the capacitor core 501 is a first distance L1, one end of the capacitor core 501 may be any one end, and the distance from the corresponding mass resonator plate 502 to the other end of the capacitor core is L-L1. Where L is the envelope length of the capacitor core 501, a known amount. It should be noted that, in the embodiment of the present application, it is assumed that the thickness of the mass resonator plate is negligible.
In the embodiment of the present application, the first distance L1 may be assigned to obtain a plurality of first distances L1, which form a first distance set. Wherein the first distance set comprises a plurality of first distances L1, and the first distance L1 is less than the envelope length L.
Step 402, calculating candidate mass of the mass resonance plate according to the mechanical characteristic parameters, the anti-resonance frequency, the first distance and the sectional area aiming at each first distance;
In the embodiment of the present application, the first distance satisfies a first formula, and the first formula is:
sinkL-kLβsinkL1sink(L-L1)＝0
Wherein the content of the first and second substances,Omega is the angular frequency of the anti-resonance frequency, and the anti-resonance frequency is determined according to the electric field force frequency of the capacitor;the wave velocity, E and rho are elastic modulus and mass density, and the elastic modulus and the mass density are determined according to the natural frequency of the capacitor; l is the envelope length of the capacitor core, L1The first distance is a distance between the first and second electrodes,The non-dimensional parameter of the mass resonance plate is A, the sectional area of the capacitor core is A, and M is the mass of the mass resonance plate.
Wherein the principle of the first formula is as follows: when the mass resonance plate is disposed at a position corresponding to the first distance in the capacitor core, and the mass of the mass resonance plate corresponds to the first distance, the natural frequency of the capacitor may be equal to the anti-resonance frequency. The natural frequency of the capacitor being equal to the anti-resonance frequency means that the natural frequency of the capacitor is not equal to the electric force frequency, i.e. that the capacitor does not resonate. Therefore, after the mass resonance plate with the corresponding mass is installed at the position corresponding to the first distance in the capacitor core calculated based on the first formula, the natural frequency of the capacitor is not equal to the electric field force frequency.
The mass of the corresponding mass resonator plate can be calculated for each first distance in the set of first distances by the first formula, thereby obtaining a plurality of candidate masses of the mass resonator plate.
And step 403, selecting a target mass from the candidate masses as the mass of the mass resonance plate.
Since there may be a situation that the candidate masses calculated in step 402 are too large to be applied to the capacitor, and since different working conditions correspond to multiple electric field force frequencies, and the anti-resonance frequency can only represent one of the multiple electric field force frequencies, the candidate masses calculated in step 402 need to be screened.
In an alternative implementation, the process of screening candidate qualities may include:
The electric field force frequency in the second formula is calculated by substituting each candidate mass M and the first distance L1 corresponding to each candidate mass into the second formula. Wherein the second formula is:
conkL-kLβsinkL1conk(L-L1)＝0
wherein the content of the first and second substances,Omega is the angular frequency of the electric field force frequency;Is the wave velocity, E is the modulus of elasticity, ρ is the mass density, L is the envelope length of the capacitor core, L1The first distance is a distance between the first and second electrodes,The non-dimensional parameter of the mass resonance plate is A, the sectional area of the capacitor core is A, and M is the mass of the mass resonance plate.
According to the second formula, the angular frequency of the electric field force frequency corresponding to each candidate mass can be calculated, and the electric field force frequency is calculated according to the angular frequency of the electric field force frequency.
when the second electric field force frequency is equal to or close to any one of the first electric field force frequencies and 0.5 frequency multiplication and 2 frequency multiplication of the first electric field force frequency, the candidate quality corresponding to the second electric field force frequency cannot achieve the purpose of staggering the natural frequency of the capacitor and the wave crest of the electric field force frequency, and the natural frequency of the capacitor and the wave crest of the electric field force frequency are not staggered, namely resonance is sent to cause noise pollution, so that the candidate quality is rejected.
When the second electric field force frequency is different from and not close to each first electric field force frequency in the plurality of first electric field force frequencies and the 0.5 frequency doubling and the 2 frequency doubling of the first electric field force frequency, and is far away from each first electric field force frequency and the 0.5 frequency doubling and the 2 frequency doubling, the candidate mass corresponding to the second electric field force frequency and the first distance corresponding to the candidate mass can enable the natural frequency of the capacitor to be staggered from the electric field force frequency, namely the natural frequency of the capacitor is not overlapped with or close to the wave crest of the electric field force frequency, so that the natural frequency of the capacitor is prevented from being transmitted to be resonant, and noise pollution can be reduced. Correspondingly, the candidate mass corresponding to the second electric field force frequency is determined as the target mass. In the embodiment of the present application, the mass of the mass resonator plate disposed in the capacitor core is the target mass.
further, in the embodiment of the present application, the mounting position of the mass resonator plate in the capacitor core is determined according to the mass of the mass resonator plate. Optionally, the first distance corresponding to the target mass is determined as the mounting position of the mass resonance plate.
it should be noted that the very important performance criteria in the capacitor include the specific characteristics, i.e. the ratio of the capacity to the mass of the capacitor. And the mass of the capacitor is primarily composed of the mass of the core elements in the capacitor core. In practical use, higher specific characteristics are better, so that generally, it is necessary to use a lighter mass as much as possible to achieve a larger capacitor capacity. In the embodiment of the application, the mass of the capacitor is increased by adding the mass resonance plate, but the added extra mass does not use the material of the capacitor core, so the specific property of the capacitor is not influenced. Although adding mass resonator plates in capacitors also adds a slight cost, it is economically reasonable overall in view of noise performance.
Further, as shown in fig. 6, the structure of the mass resonator plate in the embodiment of the present application is:
The density of the mass resonance plate is greater than the density threshold, and optionally, the mass resonance plate is a solid metal plate. Optionally, the mass resonance plate should be made of a metal material with a relatively high density, and on one hand, the mass resonance elements can be reduced as much as possible, so that the mass resonance plate has a relatively large mass adjustment range in a limited space. On the other hand, the material for manufacturing the quality resonator plate needs to pass the compatibility test with the impregnant in the capacitor, and the insulation of the impregnant cannot be destroyed.
Since the metal material itself has low damping property, in order to improve the damping effect of the mass resonance plate, in the embodiment of the present application, a damping groove 602 is provided on an end surface of the mass resonance plate 601 parallel to the wide side surface of the capacitor, where the wide side surface of the capacitor is denoted by reference numeral 7021 and the narrow side surface of the capacitor is denoted by reference numeral 7022, as shown in fig. 7.
when the electrode part of the capacitor is disturbed under the action of the electric field force, the damping groove on the mass resonance plate can play a role of buffering the disturbance of the impregnant, so that the vibration amplitude of the capacitor can be reduced.
optionally, in the embodiment of the present application, as shown in fig. 6, the depth D of the damping groove 602 is 10 to 40mm, and the height H of the damping groove 602 is 1 to 5 mm.
Optionally, in this embodiment of the application, in order to avoid that the structure is damaged due to peak benefit when the end of the mass resonator plate, at which the damping slot is formed, is used for a long time, in this embodiment of the application, the damping slot is multiple and is arranged at intervals.
In an alternative implementation, in the embodiment of the present application, a top soundproof cover is installed at the top surface position of the capacitor, a bottom soundproof cover is installed at the bottom surface position of the capacitor, and plastic foam is provided in the top soundproof cover and/or the bottom soundproof cover. The top surface position of the capacitor is the top position of the capacitor shell, namely the position of the wire outlet sleeve, the bottom surface position of the capacitor is the bottom of the outer side of the capacitor shell, and the plastic foam has a sound absorption effect.
According to the embodiment of the application, on the basis that the mass resonance plate is arranged in the capacitor core, the sound insulation covers are arranged on the top surface and the bottom surface of the shell of the capacitor and are used for absorbing vibration caused by non-resonance, noise can be absorbed more closely, and noise pollution of the capacitor is reduced.
In an alternative implementation manner, in the embodiment of the present application, damping elements are disposed on both the top and the bottom of the housing of the capacitor, wherein the capacitor core is disposed between the damping elements on the top and the bottom, and the damping elements are springs. Through setting up the spring on being provided with the basis of quality resonance board in the condenser core, when the condenser core takes place the vibration, can slow down the vibration range through the damping effect of spring to reduce the noise pollution of condenser.
the capacitor provided by the embodiment of the application can remove the noise of the capacitor, which is reduced by the resonance of the natural frequency of the capacitor and the frequency of the electric field force. The capacitor comprises a capacitor shell and a capacitor core arranged in the shell, wherein a mass resonance plate is arranged in the capacitor core, the mass resonance plate is a solid metal plate, the distance from the mass resonance plate to one end of the capacitor core is a first distance, the first distance is determined according to the mass of the mass resonance plate, and the mass of the mass resonance plate is determined according to the natural frequency of the capacitor and the electric field force frequency of the capacitor. In the embodiment of the application, the mass resonance plate is arranged in the capacitor core, the mass of the mass resonance plate and the first distance from the mass resonance plate to one end of the capacitor core are determined according to the natural frequency and the electric field force frequency of the capacitor, and the natural frequency of the capacitor can be changed according to the determined first distance and the mass of the mass resonance plate, so that the natural frequency of the capacitor and the electric field force frequency of the capacitor cannot resonate, and the purposes of removing the resonance effect and reducing the noise of the capacitor are achieved.
the capacitor provided in the embodiments of the present application will be described below by way of example.
The type of the capacitor can be AAM8.9-268.4-1W, the rated voltage is 8.9kV, the rated current is 30.15A, and the nominal capacitance value is 10.786 muF. The envelope length of the capacitor core is 670mm and the cross-sectional dimensions of the capacitor core are 355mm x 155 mm. The mass resonance plate provided in the embodiment of the present application is disposed in the capacitor core of this capacitor, and the mass of the mass resonance plate and the mounting position of the mass resonance plate are determined.
first, a vibration sweep test was performed on the capacitor before the mass resonator plate was placed. And loading single-frequency voltage to the capacitor core successively by adopting a sweep frequency loading mode, wherein the initial frequency is 50Hz, and the frequency interval is 50Hz till 1000 Hz. The corresponding electric field force frequency has a starting frequency of 100Hz, a frequency interval of 100Hz and an ending frequency of 2000 Hz. The voltage is changed, and the change of the frequency of the electric field force is realized. The amplitude of the capacitor case is proportional to the square of the voltage, and the frequency of the electric field force can be calculated according to the amplitude of the capacitor case.
As shown in fig. 7, under the above-mentioned loading condition, the vibration amplitude of the bottom surface center position of the capacitor case 702 is measured by using the laser vibrometer 701, and according to the measured loading voltage and vibration amplitude, the frequency response function of the capacitor case can be obtained, as shown in fig. 8, the 1 st order natural frequency of the capacitor appears at 1090Hz, wherein, the vibration frequency response curve in fig. 8 has a weak peak around 500Hz, because this frequency is approximately equal to 0.5 times the natural frequency of the capacitor, the capacitor generates significant super-harmonic resonance, so that the frequency response curve of the actual capacitor unit is raised.
according to the scanning test, the natural frequency of the 1 st order of the capacitor is 1090Hz, the natural frequency of the 2 nd order of the capacitor is 3270Hz, and the natural frequency of the 3 rd order of the capacitor is 5450Hz (not shown in figure 8), and only the natural frequency of the 3 rd order is considered here due to the limited voltage frequency which can be borne by the capacitor.
the elastic modulus of the capacitor is 4.60 × 109Pa and the mass density is 1.84 × 103kg/m3 according to the disclosure of step 201.
In the embodiment of the present application, the harmonic loading combination and the corresponding electric field force frequency related to the capacitor can be as shown in table 1:
TABLE 1
In table 1, 1# and 2# indicate different loading conditions (the present embodiment does not describe a specific loading condition, and only the electric field force frequency corresponding to the different loading condition is used), and with respect to the 1# and 2# loading conditions, the component having the largest electric field force frequency is concentrated in the range of 1000Hz to 1300Hz, and this frequency range is very close to the natural frequency 1090Hz of the capacitor (in the present embodiment, the natural frequency of 1 st order of the capacitor is the natural frequency of the capacitor), and based on this, in the present embodiment, the anti-resonance frequency is determined to be 1100Hz from the electric field force frequency range.
In this embodiment, the natural frequency needs to be adjusted. Generally, the natural frequency of the capacitor is lowered, i.e. the mechanical vibration amplitude of the capacitor is reduced.
in order to obtain a good noise reduction effect, in the embodiment of the present application, a mass tuning measure is adopted, and the anti-resonance frequency is used to reduce the vibration, optionally, the mass of the mass resonance plate is 9.2kg calculated according to the elastic modulus of the capacitor, the mass density, the anti-resonance frequency, the envelope length of the capacitor core, and the cross-sectional area of the capacitor core, and the mounting position parameter of the mass resonance plate is L1/L, which is 0.6.
Then, in the embodiment of the present application, a scan test is performed on the capacitor with the mass resonance plate, and a vibration frequency response function corresponding to the capacitor provided in the embodiment of the present application is measured, as shown in fig. 9, a peak of a vibration frequency of the capacitor with the mass resonance plate is obviously staggered from a peak of a vibration frequency of the capacitor without the mass resonance plate, so that the two capacitors can be effectively prevented from generating resonance.
The audible noise of the capacitor provided with the mass resonator plates under the 1# loading condition is shown in fig. 10. In fig. 10, the sound pressure level of the capacitor at the point of measurement is indicated, where the data without parentheses corresponds to the capacitor of the mass resonator plate and the data with parentheses corresponds to the capacitor of the mass resonator plate. Calculating to obtain the average sound pressure level of 61.27dB and the sound power level of 75.64dB on the measuring surface of the capacitor of the non-mass resonance plate; the measured surface average sound pressure level of the capacitor with the mass resonator plate was 48.30dB and the sound power level was 62.67 dB. Under the 1# loading condition, the mass resonator plate reduces the acoustic power of the capacitor by 12.97 dB.
the audible noise of the capacitor provided with the mass resonator plates under the 2# loading condition is shown in fig. 11. In fig. 11, the sound pressure level of the capacitor at the point of measurement is indicated, where the data without parentheses corresponds to the capacitor of the mass resonator plate and the data with parentheses corresponds to the capacitor of the mass resonator plate. Calculating to obtain the average sound pressure level of 50.37dB and the sound power level of 64.74dB on the measuring surface of the capacitor of the non-mass resonance panel; the measured surface average sound pressure level of the capacitor with the mass resonator plate was 36.27dB, and the sound power level was 50.63 dB. Under the 2# loading condition, the mass resonator plate reduces the acoustic power of the capacitor by 14.11 dB.
As can be seen from the above measurement data of fig. 10 and 11, the mass resonance plate can effectively reduce the audible noise of the capacitor unit. Within the frequency range of 1000Hz-1300Hz, the noise of the capacitor unit can be reduced by about 13-14 dB by using the quality tuning vibration reduction measure of the anti-resonance characteristic.
in summary, the capacitor provided by the embodiment of the present application can effectively reduce capacitor noise caused by resonance.
As shown in fig. 12, which shows a flowchart of a method for determining a mass of a mass resonator plate according to an embodiment of the present application, wherein the mass resonator plate is disposed in a capacitor core of a capacitor, a density of the mass resonator plate is greater than a density threshold, a distance from the mass resonator plate to one end of the capacitor core is a first distance, the first distance is determined according to a mass of the mass resonator plate, and the mass of the mass resonator plate is determined according to a natural frequency of the capacitor and an electric field force frequency of the capacitor, the method includes:
step 1201, determining mechanical characteristic parameters of the capacitor according to the natural frequency of the capacitor;
Step 1202, determining an anti-resonance frequency of a capacitor according to the electric field force frequency of the capacitor;
Step 1203, obtaining the encapsulation length of the capacitor core and the sectional area of the capacitor core;
and 1204, calculating the mass of the mass resonance plate according to the mechanical characteristic parameters, the anti-resonance frequency, the encapsulation length and the sectional area.
in one embodiment, calculating the mass of the mass resonator plate from the mechanical property parameters, the antiresonance frequency, the envelope length, and the cross-sectional area comprises:
Acquiring a first distance set, wherein the first distance set comprises a plurality of first distances, the first distances are the distances from the mass resonance plate to one end of the capacitor core, and the first distances are smaller than the encapsulation length;
Calculating the candidate mass of the mass resonance plate according to the mechanical characteristic parameters, the anti-resonance frequency, the first distance and the sectional area aiming at each first distance;
and selecting the target mass from the candidate masses as the mass of the mass resonance plate.
In one embodiment, the first distance corresponding to the target mass is determined as the mounting position of the mass resonance plate.
in one embodiment, the mechanical property parameters include modulus of elasticity and mass density.
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the claims. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the concept of the present application, which falls within the scope of protection of the present application. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims (10)

1. a capacitor comprising a capacitor case and a capacitor core mounted in the case, wherein a mass resonance plate is disposed in the capacitor core, a density of the mass resonance plate is greater than a density threshold, a distance from the mass resonance plate to one end of the capacitor core is a first distance, the first distance is determined according to a mass of the mass resonance plate, and the mass of the mass resonance plate is determined according to a natural frequency of the capacitor and a frequency of an electric field force of the capacitor.
2. A capacitor according to claim 1, wherein the mass of the mass resonator plate and the first distance satisfy a first formula:
sinkL-kLβsinkL1sink(L-L1)＝0；
Wherein the content of the first and second substances,ω is the angular frequency of the anti-resonance frequency, which is determined from the electric field force frequency of the capacitor;Is the wave velocity, E is the elastic modulus, ρ is the mass density, the elastic modulus and the mass density being determined from the natural frequency of the capacitor; l is the envelope length of the capacitor core, L1In order to be said first distance, the first distance,the parameter is a dimensionless parameter of the mass resonance plate, A is the sectional area of the capacitor core, and M is the mass of the mass resonance plate.
3. A capacitor according to claim 1, wherein the end surfaces of the mass resonator plates parallel to the wide sides of the capacitor are provided with damping grooves.
4. a capacitor according to claim 3, wherein the depth of the damping grooves is 10-40mm and the height of the damping grooves is 1-5 mm.
5. the capacitor of claim 3, wherein the damping grooves are plural and spaced apart.
6. The capacitor of claim 3, wherein a top acoustic enclosure is mounted to a top surface of the capacitor, a bottom acoustic enclosure is mounted to a bottom surface of the capacitor, and wherein the top acoustic enclosure and/or the bottom acoustic enclosure have plastic foam disposed therein.
7. A method for determining a mass of a mass resonator plate, wherein the mass resonator plate is disposed in a capacitor core of a capacitor, a density of the mass resonator plate is greater than a density threshold, a distance from the mass resonator plate to an end of the capacitor core is a first distance, the first distance is determined according to a mass of the mass resonator plate, and the mass of the mass resonator plate is determined according to a natural frequency of the capacitor and a frequency of an electric field force of the capacitor, the method comprising:
determining a mechanical characteristic parameter of the capacitor from the natural frequency of the capacitor;
Determining an anti-resonance frequency of the capacitor from an electric field force frequency of the capacitor;
Obtaining an envelope length of the capacitor core and a cross-sectional area of the capacitor core;
Calculating the mass of the mass resonance plate according to the mechanical characteristic parameter, the anti-resonance frequency, the envelope length and the sectional area.
8. the method of claim 7, wherein said calculating the mass of the mass resonator plate from the mechanical property parameter, the anti-resonance frequency, the envelope length, and the cross-sectional area comprises:
Obtaining a first set of distances, the first set of distances comprising a plurality of first distances, the first distances being distances from the mass resonator plate to an end of the capacitor core, the first distances being less than the envelope length;
calculating, for each of the first distances, a candidate mass of the mass resonator plate from the mechanical characteristic parameter, the anti-resonance frequency, the first distance, and the cross-sectional area;
And selecting a target mass from the candidate masses as the mass of the mass resonance plate.
9. the method of claim 8, further comprising:
And determining a first distance corresponding to the target mass as the installation position of the mass resonance plate.
10. The method according to any one of claims 7 to 9,
The mechanical property parameters include modulus of elasticity and mass density.
CN201910979993.4A 2019-10-15 2019-10-15 capacitor and mass determination method for mass resonator plate Pending CN110571050A (en)

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