CN111029111A - Noise reduction design method for bullet train converter based on reactive noise elimination - Google Patents
Noise reduction design method for bullet train converter based on reactive noise elimination Download PDFInfo
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- CN111029111A CN111029111A CN201811213222.6A CN201811213222A CN111029111A CN 111029111 A CN111029111 A CN 111029111A CN 201811213222 A CN201811213222 A CN 201811213222A CN 111029111 A CN111029111 A CN 111029111A
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F27/00—Details of transformers or inductances, in general
- H01F27/33—Arrangements for noise damping
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Abstract
The invention discloses a noise reduction design method of a bullet train converter based on reactive noise reduction, which is characterized by comprising the following steps of: 1) acquiring the noise frequency and the noise value of the converter; 2) determining the maximum resistance noise elimination frequency; 3) determining the length of an expansion chamber of the target reactive muffler according to the maximum reactive muffling frequency, and determining the expansion ratio of the target reactive muffler according to the muffling amount; 4) the target reactive muffler is determined according to the expansion ratio of the target reactive muffler and the length of the expansion chamber, and is installed in the duct of the converter. The invention can effectively reduce the medium and low frequency noise generated by the fan and realize the active noise reduction of the converter.
Description
Technical Field
The invention relates to a noise reduction design method of a bullet train converter based on resistance noise reduction, and belongs to the field of rail transit.
Background
The current transformer for the existing rail transit vehicle is generally integrated with the components such as the current transformer, a control box, a transformer and the like. However, since the transformer has a large weight and an alternating magnetostrictive force generated when the transformer operates is transmitted to the converter cabinet, the fatigue life of electrical components such as the converter and the control box and the structural strength of the converter cabinet are seriously affected by excessive vibration.
At present, the fixing mode of a transformer in a converter cabinet body is simple, and the transformer is directly fixed on the converter cabinet body through bolts or a damping pad is arranged between the transformer and the converter cabinet body. However, since the prior art has few studies on the parameters such as the rigidity and the mounting position of the damping pad, the performance of the damping pad is not matched and the damping pad is damaged as a result. With the rapid development of the modern rail transit industry, rail transit products such as high-speed rails, subways, intercity, locomotives and the like are gradually approaching the distance between people. The converter is one of the core components of rail transit motor car products, and the noise level of the equipment is directly related to the noise of the whole car, so that the comfort of passengers is influenced. Research shows that when parts such as a converter fan of a bullet train work, large low-frequency noise (between 100 Hz and 300 Hz) can be generated, so that the radiation noise of the converter hung at the bottom of a train body is too large, and the noise control requirement is exceeded. Meanwhile, low-frequency noise generated by equipment such as a converter fan is generally difficult to be eliminated greatly by using sound absorption sponge and other modes.
Disclosure of Invention
In view of the above problems, the invention aims to provide a noise reduction design method for a converter of a bullet train based on reactive noise reduction, which can effectively reduce medium and low frequency noise generated by a fan and realize active noise reduction of the converter.
In order to achieve the purpose, the invention adopts the following technical scheme: a noise reduction design method of a bullet train converter based on reactive noise elimination comprises the following steps: 1) acquiring the noise frequency and the noise value of the converter; 2) determining the maximum resistance noise elimination frequency; 3) determining the length of an expansion chamber of the target reactive muffler according to the maximum reactive muffling frequency, and determining the expansion ratio of the target reactive muffler according to the muffling amount; 4) the target reactive muffler is determined according to the expansion ratio of the target reactive muffler and the length of the expansion chamber, and is installed in the duct of the converter.
In one embodiment, the converter is provided with an air inlet and an air outlet, and the converter air duct is formed at a position between the air inlet and the air outlet.
In a specific embodiment, in the step 1), a normal operating mode of the converter is selected, a frequency spectrum test is performed on noise at the air inlet and the air outlet of the converter, after the frequency spectrum is analyzed, a noise frequency and a noise value of the converter are obtained, and a medium-low frequency noise frequency and a noise source of the converter are determined.
In a specific embodiment, in step 2), the maximum reactive muffling frequency is greater than or equal to 1.2 times the noise frequency of the converter.
In a specific embodiment, in the step 3), the muffling amount of the target reactive muffler is determined according to the target noise value and the noise value obtained in the step 1).
In a specific embodiment, in the step 3), the expansion ratio is determined according to the formula of the sound-deadening amount of the target reactive muffler:
wherein L is a sound deadening amount of the target reactive muffler, m is an expansion ratio of the expansion chamber of the target reactive muffler, L is a length of the expansion chamber of the target reactive muffler, and S1For the cross-sectional area, S, of the target reactive muffler connecting pipe2A cross-sectional area of the expansion chamber of the target reactive muffler;
the starting end position of the expansion chamber satisfies the formula:
the end position of the expansion chamber satisfies the formula:
in the formula, piIncident acoustic sound pressure, p, for the inlet end of the target reactive mufflerrIs the reflected sound wave sound pressure, p, of the inlet end of the target reactive mufflertAcoustic pressure of sound transmitted through the target reactive muffler for noise, wherein incident and transmitted sound propagates forward, reflected sound propagates backward, p1For sound waves propagating forwards in said expansion chamber, p2For sound waves propagating backwards in the expansion chamber, p0C is the air density at the beginning of the expansion chamber and c is the acoustic length.
In a specific embodiment, in the step 3), the length of the extension chamber is determined according to the formula of the maximum sound attenuation frequency of the extension chamber:
in the formula (f)maxWhen n is a positive integer, the length of the extension chamber is equal to an odd multiple of 1/4 wavelengths of the sound wave, the muffling amount of the target reactive muffler reaches a maximum value, and when sin (kl) is 0,i.e., kl is an even multiple of pi/2, the amount of sound deadening of the target reactive muffler reaches a minimum.
In a specific embodiment, the corresponding frequency at which the target reactive muffler has the largest amount of sound attenuation is the maximum sound attenuation frequency of the extension chamber.
In one embodiment, the frequency corresponding to the minimum muffling amount of the target reactive muffler is determined as a pass frequency, and the pass frequency is determined according to the following formula:
sin(kl)＝0 (7)
Lmin＝0 (8)
in the formula (f)tWhen the length of the expansion chamber is equal to an integral multiple of the wavelength of the 1/2 sound wave at the pass frequency, the sound wave at the corresponding pass frequency passes through without attenuation, and the target reactive muffler does not perform the sound attenuation function.
In one embodiment, the lower limit frequency of effective sound attenuation of the expansion chamber is determined according to the formula:
in the formula (f)lowV is the lower frequency of effective sound attenuation of the expansion chamber and V is the volume of the expansion chamber.
Due to the adoption of the technical scheme, the invention has the following advantages: 1. the reactive muffler can effectively reduce the noise of the converter cabinet body, so that the quality of the converter can be improved. 2. The reactive muffler provided by the invention can effectively reduce noise and has low cost without adding sound-absorbing materials during noise reduction. 3. The invention can only need to modify the local structure of the converter to play the role of silencing the silencer, and can reduce the noise reduction cost of the converter. 4. The expansion chamber of the target reactive muffler of the present invention can avoid the passing frequency and the lower limit frequency, thereby improving the muffling effect of the target reactive muffler.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by the practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
Drawings
In order to more clearly illustrate the technical solution in the embodiments of the present invention, the following briefly introduces the drawings required in the description of the embodiments:
FIG. 1 is a schematic diagram of a noise reduction process according to the present invention;
fig. 2 is a schematic structural diagram of a current transformer of the present invention;
FIG. 3 is a schematic view of the reactive muffler of the present invention in principle for reactive muffling;
fig. 4 is a schematic structural view of a fan flow channel in the inverter of the present invention.
Detailed Description
The following detailed description of the embodiments of the present invention will be provided with reference to the drawings and examples, so that how to apply the technical means to solve the technical problems and achieve the technical effects can be fully understood and implemented. It should be noted that, as long as there is no conflict, the embodiments and the features of the embodiments of the present invention may be combined with each other, and the technical solutions formed are within the scope of the present invention.
As shown in FIGS. 1 to 3, the noise reduction design method for the converter of the bullet train based on the reactive noise reduction provided by the invention comprises the following steps:
1) acquiring the noise frequency and the noise value of the converter 1;
2) determining the maximum resistance noise elimination frequency;
3) determining the length of the expansion chamber 21 of the target reactive muffler 2 according to the maximum reactive muffling frequency, and determining the expansion ratio of the target reactive muffler 2 according to the muffling amount;
4) the target reactive muffler 2 is determined according to the expansion ratio of the target reactive muffler 2 and the length of the expansion chamber 21, and the target reactive muffler 2 is installed in the duct 11 of the converter 1.
In one embodiment, as shown in fig. 2, the converter 1 comprises an air inlet 12 and an air outlet 13. The air duct 11 of the converter 1 is formed at a position between the air inlet 12 and the air outlet 13. The number of the air inlets 12 and the air outlets 13 can be set according to actual needs. Preferably, the number of the air inlets 12 is multiple, and the multiple air inlets 12 are arranged at intervals on two sides of the current transformer 1. The air outlet 13 is arranged at the edge position of the middle part of the converter 1.
In one embodiment, as shown in fig. 3, the target reactive muffler 2 includes an expansion chamber 21 and two connection pipes 22 connected at both ends of the expansion chamber 21.
In a specific embodiment, in step 1), a normal operating mode of the converter 1 is selected, a frequency spectrum test is performed on noise at the air inlet 12 and the air outlet 13 of the converter 1, after the frequency spectrum is analyzed, a noise frequency and a noise value of the converter 1 are obtained, and a medium-low frequency noise frequency and a noise source of the converter 1 are determined.
In a specific embodiment, it is determined that converter 1 noise originates from the operating frequency of the fan 3 (shown in fig. 2, 4), the fan 3 being arranged inside the converter 1. The operating frequency f of the fan 3 is 286 Hz. The air inside the converter 1 flows through the flow channel 31 of the fan 3 and flows out from the air outlet 13 of the converter 1.
In a particular embodiment, in step 2), the maximum reactive muffling frequency is equal to or greater than 1.2 times the noise frequency of the inverter in step 1).
In one embodiment, in step 3), the amount of sound deadening of the target reactive muffler 2 is determined based on the target noise value and the noise value obtained in step 1).
In one embodiment, in step 3), the amount of sound attenuation of the target reactive muffler 2 may be determined by the amount of attenuation between the incident sound intensity at the inlet end of the target reactive muffler 2 and the transmitted sound intensity at the outlet end of the target reactive muffler 2. The sound intensity is proportional to the square of the sound pressure, and the expansion ratio is determined according to the sound deadening amount of the target reactive muffler 2 by the following formula:
where L is the sound deadening amount of the target reactive muffler 2, m is the expansion ratio of the target reactive muffler 2, L is the length of the expansion chamber 21 of the target reactive muffler 2, and S1Cross-sectional area, S, of connecting pipe 2 for the target reactive muffler2The cross-sectional area of the expansion chamber 21 of the target reactive muffler 2. The sound-deadening amount of the target reactive muffler 2 is determined by the expansion ratio m, the sound-deadening frequency characteristic is determined by the length of the expansion chamber 21, sinkl is a periodic function, and the sound-deadening amount of the target reactive muffler 2 also varies periodically with the frequency.
Reactive silencing is achieved by sudden expansion (or contraction) of the cross-section of the pipe of the connecting pipe 22 to cause a sudden change in the acoustic impedance in the channel, so that sound waves of certain frequencies propagating along the pipe of the connecting pipe 22 are reflected back to the source of the excitation through less than the target reactive silencer 2. The sound wave can not pass through the target reactive muffler 2, and can not be transmitted out, so that the aim of sound attenuation is achieved. The expansion chamber 21 is formed by connecting two abrupt cross-section connecting pipes 22 in opposite phase (as shown in fig. 3).
As shown in fig. 3, the starting end position (defining starting end surface x being 0) of the extension chamber 21 satisfies the formula condition:
the end position of the expansion chamber 21 (defining the end face x as 1) satisfies the formula condition:
in the formula, piIncident acoustic sound pressure, p, at the inlet end of the target reactive muffler 2rReflected acoustic sound pressure, p, for the inlet end of the target reactive muffler 2tFor noise transmission through the target reactive muffler 2Sound pressure of outgoing sound waves, wherein incident and transmitted sound waves propagate forward, reflected sound waves propagate backward, p1For expanding the sound wave propagating forwards in the chamber 21, p2For expanding the backward propagating acoustic wave in the chamber 21, ρ0C is the acoustic wave length, which is the air density at the start position of the extension chamber 21.
In one embodiment, in step 3), the length of the expansion chamber 21 is determined from the maximum damping frequency of the expansion chamber 21 according to the formula:
in the formula (f)maxIn the case where n is a positive integer and the length of the extension chamber 21 is equal to an odd multiple of the 1/4 wavelength of the sound wave for the maximum muffling frequency of the extension chamber 21, the muffling amount of the target reactive muffler 2 reaches the maximum, and when sin (kl) is 0, that is, kl is an even multiple of pi/2, the muffling amount of the target reactive muffler 2 reaches the minimum.
In one specific embodiment, the corresponding frequency at which the amount of sound attenuation of the target reactive muffler 2 is the maximum sound attenuation frequency of the extension chamber 21.
In one embodiment, the frequency corresponding to the minimum sound-deadening amount of the target reactive muffler 2 is determined as a pass frequency, and the pass frequency is determined according to the formula:
sin(kl)＝0 (7)
Lmin＝0 (8)
in the formula (f)tWhen the length of the extension chamber 21 is equal to an integral multiple of the wavelength of the 1/2 sound wave for the passing frequency, the sound wave of the corresponding passing frequency passes without attenuation, and the target reactive muffler 2 does not perform the sound attenuation function.
In one embodiment, the target reactive muffler 2 is in a low frequency range, and when the wavelength is much longer than the length of the extension chamber 21 or the connection pipe 22, the extension chamber 21 and the connection pipe 22 can be regarded as a lumped parameter system. When the extraneous sound wave frequency is in the vicinity of the resonance frequency of this system, the target reactive muffler 2 not only fails to muffle the sound but also amplifies the sound. At this time, the frequency of the extraneous sound wave is the down line frequency of effective sound attenuation of the extension chamber 21 at the resonance frequency of this system.
The lower limit frequency of effective sound attenuation of the expansion chamber 21 is determined according to the formula:
in the formula (f)lowV is the volume of the expansion chamber 21, which is the lower limit frequency of effective sound attenuation of the expansion chamber 21.
In one embodiment, when the converter 1 duct 11 is optimized, the number of the target reactive mufflers 2 can be determined to be one or more according to actual needs. When the number of the target reactive mufflers 2 is plural, the plural target reactive mufflers 2 are connected in series to perform sound attenuation. The air duct 11 limited by space can be expanded at a local position thereof, and can play a role in noise elimination.
Although the embodiments of the present invention have been described above, the above description is only for the convenience of understanding the present invention, and is not intended to limit the present invention. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.
Claims (10)
1. A noise reduction design method of a motor car converter based on reactive noise elimination is characterized by comprising the following steps:
1) acquiring the noise frequency and the noise value of the converter;
2) determining the maximum resistance noise elimination frequency;
3) determining the length of an expansion chamber of the target reactive muffler according to the maximum reactive muffling frequency, and determining the expansion ratio of the target reactive muffler according to the muffling amount;
4) the target reactive muffler is determined according to the expansion ratio of the target reactive muffler and the length of the expansion chamber, and is installed in the duct of the converter.
2. The method for designing noise reduction of a bullet train converter based on reactive noise elimination as claimed in claim 1, wherein said converter is provided with an air inlet and an air outlet, and said converter air duct is formed at a position between said air inlet and said air outlet.
3. The method for designing noise reduction of a converter of a bullet train based on reactive noise reduction according to claim 2, wherein in the step 1), a normal working mode of the converter is selected, frequency spectrum testing is performed on noise at the air inlet and the air outlet of the converter, after the frequency spectrum is analyzed, the noise frequency and the noise value of the converter are obtained, and the medium-low frequency noise frequency and the noise source of the converter are determined.
4. The method for designing noise reduction of a converter of a motor car based on reactive noise elimination as claimed in claim 3, wherein in the step 2), the maximum reactive noise elimination frequency is greater than or equal to 1.2 times of the noise frequency of the converter in the step 1).
5. The method for designing noise reduction of a converter of a motor car based on reactive noise elimination as claimed in claim 4, wherein in the step 3), the noise elimination amount of the target reactive noise eliminator is determined according to the target noise value and the noise value obtained in the step 1).
6. The method for designing noise reduction of a converter of a motor car based on reactive noise reduction according to claim 5, wherein in the step 3), the formula for determining the expansion ratio according to the noise reduction amount of the target reactive noise reducer is as follows:
wherein L is a sound deadening amount of the target reactive muffler, m is an expansion ratio of the expansion chamber of the target reactive muffler, L is a length of the expansion chamber of the target reactive muffler, and S1For the cross-sectional area, S, of the target reactive muffler connecting pipe2A cross-sectional area of the expansion chamber of the target reactive muffler;
the starting end position of the expansion chamber satisfies the formula:
the end position of the expansion chamber satisfies the formula:
in the formula, piIncident acoustic sound pressure, p, for the inlet end of the target reactive mufflerrIs the reflected sound wave sound pressure, p, of the inlet end of the target reactive mufflertAcoustic pressure of sound transmitted through the target reactive muffler for noise, wherein incident and transmitted sound propagates forward, reflected sound propagates backward, p1For sound waves propagating forwards in said expansion chamber, p2For sound waves propagating backwards in the expansion chamber, p0C is the air density at the beginning of the expansion chamber and c is the acoustic length.
7. The method for designing noise reduction of a converter of a motor car based on reactive noise reduction according to claim 6, wherein in the step 3), the length of the expansion chamber is determined according to the formula of the maximum noise reduction frequency of the expansion chamber:
in the formula (f)maxThe muffling amount of the target reactive muffler reaches a maximum value when n is a positive integer, the length of the extension chamber is equal to an odd multiple of 1/4 wavelengths of the sound wave, and reaches a minimum value when sin (kl) is 0, i.e., kl is an even multiple of pi/2.
8. The method for designing noise reduction of a converter of a motor car based on reactive noise elimination as claimed in claim 7, wherein the corresponding frequency at which the maximum noise elimination amount of the target reactive noise eliminator is the maximum noise elimination frequency of the expansion chamber.
9. The method for designing noise reduction of a converter of a motor car based on reactive noise reduction of claim 8, wherein the corresponding frequency when the noise reduction amount of the target reactive noise reducer reaches the minimum value is determined as a passing frequency, and the formula for determining the passing frequency is as follows:
sin(kl)＝0 (7)
Lmin＝0 (8)
in the formula (f)tWhen the length of the expansion chamber is equal to an integral multiple of the wavelength of the 1/2 sound wave at the pass frequency, the sound wave at the corresponding pass frequency passes through without attenuation, and the target reactive muffler does not perform the sound attenuation function.
10. The method of claim 9, wherein the lower limit frequency of effective noise reduction of the expansion chamber is determined according to the formula:
in the formula (f)lowV is the lower frequency of effective sound attenuation of the expansion chamber and V is the volume of the expansion chamber.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113838447A (en) * | 2021-09-08 | 2021-12-24 | 青岛海尔空调器有限总公司 | Control method and system of silencer |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103161555A (en) * | 2013-03-21 | 2013-06-19 | 华电分布式能源工程技术有限公司 | Design method of silencer with circular cavity |
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Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103161555A (en) * | 2013-03-21 | 2013-06-19 | 华电分布式能源工程技术有限公司 | Design method of silencer with circular cavity |
Non-Patent Citations (1)
| Title |
|---|
| 学习百眼通: "扩张室消声器", 《噪声分析常用计算公式汇总（四）：消声降噪》 * |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113838447A (en) * | 2021-09-08 | 2021-12-24 | 青岛海尔空调器有限总公司 | Control method and system of silencer |
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Application publication date: 20200417 |