CN106839386B - Active noise reduction system and method for tower type air purifier - Google Patents
Active noise reduction system and method for tower type air purifier Download PDFInfo
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- CN106839386B CN106839386B CN201710046648.6A CN201710046648A CN106839386B CN 106839386 B CN106839386 B CN 106839386B CN 201710046648 A CN201710046648 A CN 201710046648A CN 106839386 B CN106839386 B CN 106839386B
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
- F24F13/00—Details common to, or for air-conditioning, air-humidification, ventilation or use of air currents for screening
- F24F13/24—Means for preventing or suppressing noise
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R3/00—Circuits for transducers, loudspeakers or microphones
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
- F24F13/00—Details common to, or for air-conditioning, air-humidification, ventilation or use of air currents for screening
- F24F13/24—Means for preventing or suppressing noise
- F24F2013/247—Active noise-suppression
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Abstract
The invention discloses an active noise reduction system and method for a tower type air purifier. The noise reduction system includes: noise detection device, noise reduction unit and noise cancellation device. The noise detection device includes: microphones, vibration sensors; the noise reduction unit comprises an analog-to-digital conversion circuit, a feedforward filter and a digital-to-analog conversion circuit; the noise elimination device is a loudspeaker. The active noise reduction method comprises the following steps: the method comprises the steps of detecting a noise signal and a vibration signal by using a microphone and a vibration sensor respectively, determining the transmission characteristic of noise according to the signals, designing a feedforward filter according to the transmission characteristic of the noise, obtaining a noise elimination signal by the noise signal and the vibration signal through the feedforward filter, and playing the noise elimination signal by a loudspeaker to eliminate the noise. The active noise reduction method for the tower type air purifier can achieve a good noise reduction effect, and the air purifier can emit less noise while purifying indoor polluted air.
Description
Technical Field
The invention belongs to the technical field of voice signal processing, and particularly relates to an active noise reduction system and method for a tower type air purifier.
Background
In recent years, haze is an environmental pollution topic which is always a popular suggestion for people, people gradually realize that the haze environment in a long-time environment can cause great harm to human bodies, respiratory diseases are caused slightly, and cancer is possibly caused seriously. For this reason, in haze weather, people reduce on the one hand and go out to wear professional protective facial mask when going out, on the other hand closes door and window and uses air purifier indoor air purification in indoor, reduces the injury of haze to the health as far as. However, the air purifier may cause noise pollution while purifying air. Most air purifiers have noise exceeding 50dB when running at high power, and work and life in the noise environment for a long time are not beneficial to physical and mental health of people.
In order to eliminate environmental noise, there are two methods, namely passive noise reduction and active noise reduction, and for passive noise reduction, the noise can be reduced by changing the structure of the air purifier, placing corresponding sound absorption materials and the like. For active noise reduction, a microphone, a speaker and a noise reduction module can be placed in an air duct generating noise to realize noise elimination. The passive noise reduction can eliminate the noise of high frequency band, and the active noise reduction can eliminate the noise of middle and low frequency band. Patent CN104848432A has designed an air purifier of taking initiative noise reduction device, and the initiative noise reduction device includes two microphones and a speaker, adopts the self-adaptation feedforward filter that has the FIR structure to realize the function of making an uproar, this kind of noise reduction method based on unidirectional detection noise characteristic and in view of the above online design feedforward filter, and its shortcoming lies in that on the one hand the noise propagation characteristic can't comprehensive description and then influence feedforward filter's design effect, and on the other hand online design feedforward filter requires highly to the hardware, is difficult to realize.
Disclosure of Invention
In order to solve the noise problem of the tower type air purifier, the invention provides an active noise reduction system and method for the tower type air purifier, and a feedforward filter which is easy to realize is designed on the basis of comprehensively describing the noise transfer characteristic.
The invention provides an active noise reduction system for a tower type air purifier, which comprises: noise detection device, noise reduction unit and noise cancellation device. The noise detection device includes: a microphone and a vibration sensor; the noise reduction unit comprises an analog-to-digital conversion circuit, a feedforward filter circuit and a digital-to-analog conversion circuit; the noise elimination device is a loudspeaker.
Wherein two microphones are provided, placed near the noise source and near the loudspeaker, respectively, and a vibration sensor is placed near the noise source.
The feedforward filter and the feedback filter are both IIR structure filters, and the order of the filter is determined according to the balance of the filtering effect and the filter parameter setting difficulty.
The invention also provides an active noise reduction method for the tower type air purifier, which utilizes the active noise reduction system for the tower type air purifier to detect a noise signal and a vibration signal respectively by utilizing the microphone and the vibration sensor, determines the transmission characteristic of the noise according to the signals, designs the feedforward filter according to the noise transmission characteristic, obtains a noise elimination signal by the noise signal and the vibration signal through the feedforward filter, and plays the noise elimination signal by the loudspeaker to realize the elimination of the noise.
Wherein, the noise transmission characteristic is described by adopting a transfer function expression.
Wherein, the feedforward filter adopts an off-line design method.
Wherein two feedforward filters are designed, and the weighted sum of the output signals of the two feedforward filters is a noise elimination signal.
Compared with the prior art, the invention has the advantages that: because the noise signal and the vibration signal are respectively adopted to describe the propagation characteristic of the noise, the two feedforward filters are respectively designed based on the characteristic, and the weighted sum of the output signals of the two feedforward filters is used as the noise elimination signal, the method has more comprehensive description on the propagation characteristic of the noise, and is beneficial to the calculation of the noise elimination signal.
Drawings
FIG. 1 is a functional block diagram of an active noise reduction system for a tower air purifier;
fig. 2 is a block diagram of a filter design.
Detailed Description
For further understanding of the technical solutions and advantages of the present invention, the present invention will now be described in detail with reference to the accompanying drawings and examples.
The invention relates to an active noise reduction system for a tower type air purifier. The noise detection means comprises two microphones and a vibration sensor. The noise reduction unit comprises an analog-to-digital conversion circuit, two feedforward filters and a digital-to-analog conversion circuit; the noise cancellation device is a loudspeaker. Two microphones are placed near the noise source and near the speaker, respectively, for collecting noise signals. The vibration sensor is arranged near the noise source and used for collecting vibration signals corresponding to the noise signals. The analog/digital conversion circuit converts the noise signal and the vibration signal into digital signals and respectively transmits the digital signals to the feedforward filter, after the digital signals are processed by the feedforward filter, the digital/analog conversion circuit converts the output signal of the feedforward filter into an analog signal and transmits the analog signal to the loudspeaker, and the loudspeaker is used as a noise elimination device and plays the analog signal to counteract the noise signal so as to achieve the purpose of eliminating the noise.
The active noise reduction method comprises the following steps: as shown in fig. 1. Detecting noise signals p near a noise source using a microphone and a vibration sensor, respectively1(t) and a vibration signal v (t), while detecting a noise signal p placed in the vicinity of the loudspeaker by means of a microphone2(t) of (d). By p1(t) and p2(t), v (t) and p2(t) determining the noise transfer characteristics, represented by the Z transfer function, respectively denoted G1(z) and G2(z) and the sound transmission characteristics of the loudspeaker are denoted as s (z), and the noise reduction system can be denoted as G1 w + G2 (1-w), where w is a weight coefficient, w is 0 ≦ 1, and the value of w is related to the modeling accuracy of the noise characteristics G1 and G2, and the weight with high degree of fitting is significant, or vice versa. To minimize the noise reduction system output E, the feedforward filter H1 ═ G1/S × w and the feedforward filter H2 ═ G2/S × 1-w. Since s (z) is a non-minimum phase system, H1 and H2 obtained by the above method are unstable, and for this purpose, feedforward filters H1 and H2 are found by using the structure shown in fig. 2 according to the principle that linear systems are exchangeable. Firstly, the sound transmission characteristics S (z) of the loudspeaker are determined, and then the noise signal p is transmitted1(t) and the vibration signal v (t) are passed through a loudspeaker S (z) to obtain a signal p1'(t) and v' (t), then p1’(t)、p2(t) is input/output, and v' (t), p2(t) is input and output, and a feedforward filter is obtained.
The structure of the output error model is shown as formula (1):
where y (t), u (t), and e (t) represent the output, input, and error of the model, respectively.
B (z) and F (z) are respectively numerator polynomial and denominator polynomial, as shown in formula (2) and formula (3),
B(z)＝b1+b2z-1+…+bnbz-nb+1(2)
F(z)＝1+f1z-1+…+fnfz-nf(3)
wherein b is1，b2...bnb，f1，f2...fnfThe coefficients of the numerator polynomial and the denominator polynomial are respectively expressed, and the numerator, nb and nf respectively express the order of the numerator polynomial and the denominator polynomial.
The noise transfer characteristic Z transfer function expression is shown in equation (4).
White noise signal or pink noise signal n1(t) is used as input signal of loudspeaker, and output signal n2(t) of loudspeaker is detected by microphone, and noise signal n is used1(t) and a noise signal n2(t) as input and output of the output error model, determining parameters in the formula (4) by using a least square identification method on the basis of determining numerator, denominator order nb and nf, and further obtaining S (z).
Will signal p1' (t) and noise signal p2(t) as the input and output of the output error model, determining the parameters in the formula (4) by using a least square identification method on the basis of determining the numerator, the denominator order nb and nf to obtain a feedforward filter H1(z), and similarly, converting the signal v' (t) and the noise signal p (p)2(t) as the input and output of the output error model, determining the parameters in the formula (4) by using a least square identification method on the basis of determining the numerator, the denominator order nb and nf, and obtaining the feedforward filter H2 (z).
The exemplary embodiments of the present invention and their description are provided to illustrate the present invention, but not to limit the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the invention without making any creative effort, are within the protection scope of the invention.
Claims (5)
1. An active noise reduction system for a tower air purifier, the noise reduction system comprising: noise detection device, noise reduction unit and noise elimination device, noise detection device includes: a microphone and a vibration sensor; the noise reduction unit comprises an analog-to-digital conversion circuit, a feedforward filter circuit and a digital-to-analog conversion circuit; the noise elimination device is a loudspeaker;
two microphones are provided and respectively placed near a noise source and a loudspeaker, and a vibration sensor is placed near the noise source;
because the noise signal and the vibration signal are respectively adopted to describe the propagation characteristic of the noise, and two feedforward filters are respectively designed based on the characteristic, and the weighted sum of the output signals of the two feedforward filters is used as a noise elimination signal, the method has more comprehensive description on the propagation characteristic of the noise, and is beneficial to the calculation of the noise elimination signal;
the feedforward filter is a filter with an IIR structure, and the order of the filter is determined according to the balance of the filtering effect and the setting difficulty of filter parameters.
2. An active noise reduction method for a tower-type air purifier, which utilizes the active noise reduction system for the tower-type air purifier of claim 1, characterized in that the method respectively utilizes a microphone and a vibration sensor to detect a noise signal and a vibration signal, determines the transmission characteristic of the noise according to the signals, designs a feedforward filter according to the transmission characteristic of the noise, obtains a noise elimination signal by the noise signal and the vibration signal through the feedforward filter, and plays the noise elimination signal through a loudspeaker to eliminate the noise.
3. The active noise reduction method for the tower-type air purifier as claimed in claim 2, wherein the noise transmission characteristic is described by a transfer function expression.
4. The active noise reduction method for a tower air purifier of claim 2, wherein the feedforward filter is designed off-line.
5. The active noise reduction method for a tower air purifier of claim 2, wherein two feedforward filters are designed, and the weighted sum of the output signals of the two feedforward filters is the noise reduction signal.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN107393545B (en) * | 2017-07-17 | 2020-12-08 | 会听声学科技（北京）有限公司 | Feedback type active noise reduction system and method with flexible gain |
| CN107560142A (en) * | 2017-10-18 | 2018-01-09 | 会听声学科技（北京）有限公司 | A kind of active noise reducing device and method suitable for central air-conditioning |
| CN108389570B (en) * | 2018-01-31 | 2021-10-29 | 广东思派康电子科技有限公司 | Active noise reduction device and open space active noise reduction method |
| CN110418225A (en) * | 2018-04-26 | 2019-11-05 | 深圳市韶音科技有限公司 | A kind of microphone apparatus |
| CN108810692A (en) * | 2018-05-25 | 2018-11-13 | 会听声学科技（北京）有限公司 | Active noise reduction system, active denoising method and earphone |
| CN111947926B (en) * | 2020-07-10 | 2022-07-15 | 西安工程大学 | Intelligent sliding bearing self-adaptive active noise reduction device and noise reduction method |
| CN112562627B (en) * | 2020-11-30 | 2021-08-31 | 深圳百灵声学有限公司 | Feedforward filter design method, active noise reduction method, system and electronic equipment |
| CN112562626B (en) * | 2020-11-30 | 2021-08-31 | 深圳百灵声学有限公司 | Design method of hybrid noise reduction filter, noise reduction method, system and electronic equipment |
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| CN1691702A (en) * | 2004-04-26 | 2005-11-02 | 明基电通股份有限公司 | Noise cancellation apparatus, method, and electronic communication device using noise cancellation apparatus |
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| CN104848432A (en) * | 2015-05-29 | 2015-08-19 | 东南大学 | Air purifier with active noise reduction device |
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| JP2921232B2 (en) * | 1991-12-27 | 1999-07-19 | 日産自動車株式会社 | Active uncomfortable wave control device |
| JPH086576A (en) * | 1994-06-15 | 1996-01-12 | Hitachi Plant Eng & Constr Co Ltd | Noise reducing method and device therefor |
| EP2667379B1 (en) * | 2012-05-21 | 2018-07-25 | Harman Becker Automotive Systems GmbH | Active noise reduction |
| CN105025418B (en) * | 2014-04-17 | 2018-10-09 | 山东共达电声股份有限公司 | A kind of active noise reduction controller |
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| CN1691702A (en) * | 2004-04-26 | 2005-11-02 | 明基电通股份有限公司 | Noise cancellation apparatus, method, and electronic communication device using noise cancellation apparatus |
| CN102461204A (en) * | 2009-04-28 | 2012-05-16 | 伯斯有限公司 | Dynamically configurable anr filter and signal processing topology |
| CN104848432A (en) * | 2015-05-29 | 2015-08-19 | 东南大学 | Air purifier with active noise reduction device |
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