CN118250607A - Vibrating table power amplifier noise control method and device - Google Patents
Vibrating table power amplifier noise control method and device Download PDFInfo
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- G—PHYSICS
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- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01M7/00—Vibration-testing of structures; Shock-testing of structures
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- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01M7/00—Vibration-testing of structures; Shock-testing of structures
- G01M7/02—Vibration-testing by means of a shake table
- G01M7/022—Vibration control arrangements, e.g. for generating random vibrations
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- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
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Abstract
The invention relates to a method and a device for controlling noise of a power amplifier of a vibrating table, belongs to the technical field of industrial control, and solves the problems that the existing power amplifier of the vibrating table needs to control noise by means of other devices and the noise suppression effect is unstable. Comprising the following steps: performing short-time Fourier transform on the voltage signal output by the power amplifier of the vibrating table to obtain a frequency domain signal, and calculating the original power spectrum density of each frequency point in the frequency domain signal; obtaining the minimum power spectral density of each frequency point; identifying noise points according to the frequency band of the vibrating table where each frequency point is located and the minimum power spectral density of each frequency point, and correcting the original power spectral density; calculating the noise existence probability and the gain of the noise point, multiplying the gain of the noise point with the frequency domain signal, and then performing inverse short-time Fourier transform to obtain a noise-reduced voltage signal; and inputting the noise-reduced voltage signal and the voltage given signal into a PID controller, controlling the on-off of an IGBT bridge arm in the power amplifier of the vibrating table, and outputting the voltage signal. The self-adaptive noise suppression is realized, and the real-time performance of industrial control is met.
Description
Technical Field
The invention relates to the technical field of industrial control, in particular to a method and a device for controlling power amplification noise of a vibrating table.
Background
The performance of the vibrating table plays a decisive role in vibration test, and a high-power amplifier is more important as a driving of the vibrating table. The power amplifier of the vibrating table plays a role in amplifying a low-power signal into a power signal, and is generally powered by three-phase alternating current after rectifying and filtering due to high energy required by equipment.
In the whole power amplification system, due to the existence of objective factors such as harmonic interference of a power grid, switching noise of a power tube, power frequency interference and the like, a large amount of noise exists in output of the power amplification system, the noise can influence the tested condition of a tested piece, irreversible damage can be caused to the tested piece when the noise is serious, and the test platform is used for checking noise floor as an important index, so that the performance of the vibrating table is directly determined. Therefore, noise reduction design is performed on the output signal when designing the power amplifier.
The existing noise reduction of the power amplifier mainly utilizes an analog filter, and the principle of the existing noise reduction of the power amplifier is that a high-pass, low-pass and band-stop filter manufactured by an analog device is connected in series at an output end. The output voltage rating in the work of the power amplifier is 200V, the instantaneous current reaches 300 ampere level, and a passive filter consisting of an inductor, a resistor and a capacitor can be used, so that the cost and the volume of the system are increased, the large-scale mass production link is obvious, and the automatic data acquisition and monitoring control in the industrial control cannot be realized. In addition, under different working conditions of the vibrating table, the existing mode cannot realize stable and reliable noise suppression, so that the effect of process control in industrial control is poor.
Disclosure of Invention
In view of the above analysis, the embodiment of the invention aims to provide a method and a device for controlling the noise of a power amplifier of a vibrating table, which are used for solving the problems that the existing power amplifier of the vibrating table needs to control the noise by other devices and the noise suppression effect is unstable.
In one aspect, an embodiment of the present invention provides a method for controlling noise of a power amplifier of a vibrating table, including the following steps:
Performing short-time Fourier transform on the voltage signal output by the power amplifier of the vibrating table to obtain a frequency domain signal, and calculating the original power spectrum density of each frequency point in the frequency domain signal;
Performing bidirectional search on the original power spectrum density of each frequency point to obtain the minimum power spectrum density of each frequency point; identifying noise points according to the frequency band of the vibrating table where each frequency point is located and the minimum power spectral density of each frequency point, and correcting the original power spectral density to obtain corrected power spectral density;
Calculating the noise existence probability according to the minimum power spectral density of the noise point and the corrected power spectral density, calculating the gain of the noise point, multiplying the gain of the noise point with the frequency domain signal, and then performing inverse short-time Fourier transform to obtain a voltage signal after noise reduction;
And inputting the noise-reduced voltage signal and the voltage given signal into a PID controller, comparing the output of the PID controller with the set triangular wave, controlling the on-off of the IGBT bridge arm in the power amplifier of the vibrating table, and outputting the voltage signal.
Based on the further improvement of the method, the bidirectional searching of the original power spectrum density of each frequency point is carried out to obtain the minimum power spectrum density of each frequency point, which comprises the following steps: sequentially taking each frequency point as a center, respectively expanding the frequency bands backwards and forwards according to a preset frame number, and taking the minimum power spectral density in the two expanded frequency bands as a first spectral density and a second spectral density; and taking the maximum value of the first spectral density and the second spectral density as the minimum power spectral density of the current frequency point.
Based on a further improvement of the above method, the frequency bands of the vibrating table include an in-band frequency range, an out-of-band frequency range, and a sampling frequency range, each frequency band corresponding to a noise spectrum threshold.
Based on the further improvement of the method, the noise point is identified according to the frequency band of the vibrating table where each frequency point is located and the minimum power spectral density of each frequency point, and the method comprises the following steps:
Taking the ratio of the original power spectral density to the minimum power spectral density of each frequency point as noise spectral quantity, and acquiring a corresponding noise spectral threshold value according to the frequency band of the vibrating table where each frequency point is positioned as a comparison threshold value; and taking the frequency points with the noise spectrum quantity larger than the comparison threshold value as noise points.
Based on further improvement of the method, the original power spectrum density is estimated and corrected to obtain corrected power spectrum density, which comprises the following steps:
according to the ratio of the first spectral density to the second spectral density of each frequency point, obtaining the spectral density variation of each frequency point, and comparing the spectral density variation with a preset variation threshold value:
when the spectral density variation is smaller than the variation threshold, directly taking the minimum power spectral density of the frequency point as the corrected power spectral density of the frequency point;
when the spectral density variation is greater than or equal to the variation threshold, if the frequency point is not a noise point, the power spectral density of the frequency point is unchanged, and if the frequency point is a noise point, the power spectral density corrected by the frequency point before the frequency point is taken as the power spectral density corrected by the frequency point.
Based on a further improvement of the method, the corrected power spectral density is normalized by the ratio of the number of sampling instants in a frame of signal to the oversampling rate.
Based on further improvement of the method, the noise existence probability is calculated according to the minimum power spectral density of the noise point and the corrected power spectral density through the following formula:
Where P (f z, k) represents the noise existence probability of the noise point f z at the sampling time k, ω (f z, k) represents the power spectral density after correction of the noise point f z, C min(fz, k) represents the minimum power spectral density of the noise point f z, θ represents the noise probability threshold, and β represents the scaling factor.
Based on a further improvement of the method, the gain of the noise point is calculated by the following formula:
Where G y(fz, k) represents the gain of noise point f z at sample time k, Indicating the conditional gain in the presence of noise, G min indicates the lower gain limit.
Based on a further improvement of the above method, the conditional gain when noise exists is calculated by using the noise existence probability by the following formula:
On the other hand, the embodiment of the invention provides a power amplifier noise control device of a vibrating table, which comprises the following components:
The signal acquisition module is used for carrying out short-time Fourier transform on the voltage signal output by the power amplifier of the vibrating table to obtain a frequency domain signal, and calculating the original power spectral density of each frequency point in the frequency domain signal;
The noise analysis module is used for carrying out bidirectional search on the original power spectral density of each frequency point to obtain the minimum power spectral density of each frequency point; identifying noise points according to the frequency band of the vibrating table where each frequency point is located and the minimum power spectral density of each frequency point, and correcting the original power spectral density to obtain corrected power spectral density;
The noise control module is used for calculating the noise existence probability according to the minimum power spectral density of the noise point and the corrected power spectral density, calculating the gain of the noise point, multiplying the gain of the noise point with the frequency domain signal, and then performing inverse short-time Fourier transform to obtain a voltage signal after noise reduction;
the signal output module is used for inputting the noise-reduced voltage signal and the voltage given signal into the PID controller, comparing the output of the PID controller with the set triangular wave, controlling the on-off of the IGBT bridge arm in the power amplifier of the vibrating table and outputting the voltage signal.
Compared with the prior art, the invention has at least one of the following beneficial effects:
1. The minimum power spectral density is determined through bidirectional searching through multi-frame frequency bandwidth, so that the searching efficiency is improved; the method is characterized in that the noise point in the corresponding frequency band is identified according to the in-band frequency, the out-of-band frequency and the sampling frequency of the power amplifier of the vibrating table, the noise existence probability is reversely deduced by utilizing the power spectrum density of the noise point, so that the gain is calculated according to the noise point, the suppression effect is remarkable, the calculated amount is reduced, the noise is adaptively suppressed in the process control, the real-time performance of industrial control is met, and the safety and the stability of the vibrating table structure under various dynamic loading conditions are ensured.
2. The noise of the power amplifier of the vibrating table is restrained through an algorithm, and then the voltage signal after noise reduction is introduced into a PID control feedback loop of the power amplifier of the vibrating table, so that the data acquisition and monitoring control in industrial control are realized in a mode of combining the algorithm with hardware, the noise level of the power amplifier of the vibrating table is effectively reduced under the condition of not increasing the hardware cost and the complexity of the device, and the power amplifier can reach more optimal factory rating.
In the invention, the technical schemes can be mutually combined to realize more preferable combination schemes. 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 practice of the invention. The objectives and other advantages of the invention may be realized and attained by the structure particularly pointed out in the written description and drawings.
Drawings
The drawings are only for purposes of illustrating particular embodiments and are not to be construed as limiting the invention, like reference numerals being used to refer to like parts throughout the several views.
FIG. 1 is a flowchart of a method for controlling power amplifier noise of a vibrating table according to embodiment 1 of the present invention;
fig. 2 is a schematic structural diagram of a power amplifier noise control device for a vibrating table in embodiment 2 of the present invention.
Detailed Description
The following detailed description of preferred embodiments of the application is made in connection with the accompanying drawings, which form a part hereof, and together with the description of the embodiments of the application, are used to explain the principles of the application and are not intended to limit the scope of the application.
Example 1
The invention discloses a method for controlling the noise of a power amplifier of a vibrating table, which is shown in fig. 1 and comprises the following steps:
S1, performing short-time Fourier transform on a voltage signal output by a power amplifier of the vibrating table to obtain a frequency domain signal, and calculating the original power spectral density of each frequency point in the frequency domain signal.
The voltage signal output by the power amplifier of the vibrating table is converted into a digital quantity by the analog-to-digital converter to obtain a time domain signal of the voltage signal. Since the output voltage signal is an aperiodic signal, a frequency domain signal is obtained by using short-time Fourier transform, and the formula is as follows:
Wherein Y k represents a frequency domain signal of the voltage signal, x (k) represents a sampling value of the voltage signal at a sampling time k, h (·) represents a window function, n represents time, and w represents an angular frequency.
Further, the original power spectral density of each frequency point in the frequency domain signal is calculated by the following formula:
Where P x represents the original power spectral density and N represents the number of sampling instants in a frame of signal.
Considering that the voltage signal has quantization errors when converted into digital quantities by an analog-to-digital converter, the original power spectral density is smoothed out using a first order recursive filter, the formula is as follows:
C(f,k)＝ηC(f-1,k)+(1-η)Px (3)
Where C (f, k) represents the original power spectral density of the smoothed output, η represents the filter coefficient, its value determines the suppression degree of the noise peak, and f represents the frequency bin.
S2, carrying out bidirectional search on the original power spectral density of each frequency point to obtain the minimum power spectral density of each frequency point; and identifying noise points according to the frequency band of the vibrating table where each frequency point is located and the minimum power spectral density of each frequency point, and correcting the original power spectral density to obtain the corrected power spectral density.
It should be noted that, performing bidirectional search on the original power spectrum density of each frequency point to obtain the minimum power spectrum density of each frequency point includes:
① And sequentially taking each frequency point as a center, respectively expanding the frequency bands backwards and forwards according to the preset frame number, and taking the minimum power spectral density in the two expanded frequency bands as a first spectral density and a second spectral density.
Specifically, a current frequency point f is taken as a center, a corresponding frequency bandwidth Z is determined according to a preset frame number, a backward expanded frequency band interval is [ f-Z+1, f ], and the minimum power spectral density of the frequency band interval is obtained as a first spectral density C min1 (f, k); the forward spread band interval is [ f, f+Z-1], and the minimum power spectral density of the band interval is obtained as the second spectral density C min2 (f, k).
② Taking the maximum value of the first spectral density and the second spectral density as the minimum power spectral density C min (f, k) of the current frequency point, namely: c min(f,k)＝max{Cmin1(f,k),Cmin2 (f, k).
It should be noted that, when the vibrating table power amplifier system is designed, three key parameters of in-band frequency, out-of-band frequency and sampling frequency need to be set: the in-band frequency is the frequency of the test performed by the vibrating table, and the vibrating table in the in-band frequency can effectively simulate vibration in an external environment and provide accurate dynamic loading for a structure or equipment; the out-of-band frequencies, which typically include the natural frequency and resonant frequency of the system, need to be avoided when testing to avoid causing structural loss or failure of the vibrating table; the sampling frequency is the number of times of sampling input or output signals per second when the vibrating table power amplification system performs data acquisition and signal processing, and directly influences the frequency range of the signals which can be accurately simulated and measured by the system, thereby influencing the accuracy and reliability of the test result.
Therefore, the embodiment focuses on the noise in three frequency ranges of in-band frequency, out-of-band frequency and sampling frequency of the vibrating table, reduces the calculated amount, meets the real-time performance of industrial control, and ensures the safety and stability of the vibrating table structure under various dynamic loading conditions.
Specifically, the corresponding in-band frequency range, out-of-band frequency range, and sampling frequency range are set as three frequency bands, one noise spectrum threshold for each frequency band, respectively, according to the in-band frequency, out-of-band frequency, and sampling frequency.
Illustratively, the in-band frequency is 1KHZ, the corresponding in-band frequency range is [1,1K ], and the noise spectrum threshold delta 1 is 2; the out-of-band frequency is 3.7KHZ, the corresponding out-of-band frequency range is (1K, 3.7K), the noise spectrum threshold delta 2 is 2, the sampling frequency is 10KHZ, the corresponding sampling frequency range is (3.7K, 5K), and the noise spectrum threshold delta 3 is 5.
Further, identifying the noise point according to the frequency band of the vibrating table where each frequency point is located and the minimum power spectral density of each frequency point comprises: taking the ratio of the original power spectral density to the minimum power spectral density of each frequency point as noise spectral quantity, and acquiring a corresponding noise spectral threshold value according to the frequency band of the vibrating table where each frequency point is positioned as a comparison threshold value; and taking the frequency points with the noise spectrum quantity larger than the comparison threshold value as noise points.
Finally, modifying the original power spectrum density by adopting different modes for the noise point and the non-noise point in the frequency point, including:
according to the ratio of the first spectral density to the second spectral density of each frequency point, obtaining the spectral density variation of each frequency point, and comparing the spectral density variation with a preset variation threshold value:
when the spectral density variation is smaller than the variation threshold, directly taking the minimum power spectral density of the frequency point as the corrected power spectral density of the frequency point;
when the spectral density variation is greater than or equal to the variation threshold, if the frequency point is not a noise point, the power spectral density of the frequency point is unchanged, and if the frequency point is a noise point, the power spectral density corrected by the frequency point before the frequency point is taken as the power spectral density corrected by the frequency point.
Power spectral density after correction of each frequency pointExpressed by the following formula:
Wherein C d(f,k)＝Cmin1(f,k)/Cmin2 (f, k) represents the spectral density variation of the frequency bin, and α represents the variation threshold.
Further, the corrected power spectrum density is normalized by using the ratio of the number of sampling moments and the oversampling rate of a frame of signal, so as to obtain the final corrected power spectrum density omega (f, k), and the formula is as follows:
Wherein nSamp denotes the oversampling rate.
S3, calculating the noise existence probability according to the minimum power spectral density of the noise point and the corrected power spectral density, calculating the gain of the noise point, multiplying the gain of the noise point with the frequency domain signal, and then performing inverse short-time Fourier transform to obtain the voltage signal after noise reduction.
The noise existence probability is inversely deduced according to the power spectral density ω (f z, k) corrected by the noise point f z identified in step S2 by the following formula:
Where P (f z, k) represents the noise existence probability of the noise point f z at the sampling time k, ω (f z, k) represents the power spectral density after correction of the noise point f z, C min(fz, k) represents the minimum power spectral density of the noise point f z, θ represents the noise probability threshold, and β represents the scaling factor.
Based on the OM-LSA algorithm, according to the noise existence probability, the gain of the noise point is calculated by the following formula:
Where G y(fz, k) represents the gain of noise point f z at sample time k, Indicating the conditional gain in the presence of noise, G min indicates the lower gain limit.
Compared with the prior art, the voltage signal output by the power amplifier of the vibrating table in the embodiment is known, noise mainly comes from the nonlinear characteristic of the control device, the power spectrum density of the noise is concentrated at the resonant frequency and the switching frequency, and the noise power of the frequency ranges does not change along with the change of the input signal, so that when the conditional gain of the noise exists is calculated, the prior signal-to-noise ratio and the posterior signal-to-noise ratio are not required to be calculated, and the noise existence probability is directly calculated by the following formula:
Obtaining the gain of the noise point according to the formula (7) and the formula (8), wherein other non-noise points in the frequency point have no gain, and filtering the gain of the noise point by adopting a triangular filter to remove interference information.
Finally, the gain G y(fz, k) of the noise point after filtering is multiplied by the frequency domain signal Y k, and then the inverse short-time fourier transform is performed, so as to obtain the voltage signal after noise reduction.
S4, inputting the noise-reduced voltage signal and the voltage given signal into a PID controller, comparing the output of the PID controller with the set triangular wave, controlling the on-off of the IGBT bridge arm in the power amplifier of the vibrating table, and outputting the voltage signal.
After the noise-reduced voltage signal and the voltage set signal are transmitted into PID control, subtracting to obtain a deviation value e k, introducing the deviation value into a feedback loop through a voltage ring in a power amplifier of a vibrating table, comparing the output of the PID controller with a set 20KHZ triangular wave, and if the output is larger than the set triangular wave, controlling the upper tube of an IGBT bridge arm to be conducted and the lower tube to be closed; otherwise, the upper tube of the IGBT bridge arm is controlled to be closed, the lower tube is controlled to be conducted, and a multi-level voltage signal is output.
Compared with the prior art, the method for controlling the power amplification noise of the vibrating table provided by the embodiment carries out bidirectional searching through multi-frame frequency bandwidth to determine the minimum power spectral density, so that the searching efficiency is improved; recognizing noise points in corresponding frequency bands according to in-band frequency, out-of-band frequency and sampling frequency of the power amplifier of the vibrating table, and reversely calculating the noise existence probability by utilizing the power spectrum density of the noise points, so that the gain is calculated according to the noise points, the suppression effect is remarkable, the calculated amount is reduced, the noise is adaptively suppressed in the process control, the real-time performance of industrial control is met, and the safety and stability of the vibrating table structure under various dynamic loading conditions are ensured; the noise of the power amplifier of the vibrating table is restrained through an algorithm, and then the voltage signal after noise reduction is introduced into a PID control feedback loop of the power amplifier of the vibrating table, so that the data acquisition and monitoring control in industrial control are realized in a mode of combining the algorithm with hardware, the noise level of the power amplifier of the vibrating table is effectively reduced under the condition of not increasing the hardware cost and the complexity of the device, and the power amplifier can reach more optimal factory rating.
Example 2
In another embodiment of the present invention, a power amplification noise control apparatus for a vibrating table is disclosed for suppressing noise in a voltage signal output from a power amplification system of the vibrating table according to a power amplification noise control method for the vibrating table in embodiment 1. The specific implementation of each module is described with reference to the corresponding description in embodiment 1. As shown in fig. 2, the apparatus includes:
The signal acquisition module 101 is used for performing short-time fourier transform on the voltage signal output by the power amplifier of the vibrating table to obtain a frequency domain signal, and calculating the original power spectral density of each frequency point in the frequency domain signal;
The noise analysis module 102 is configured to perform bidirectional search on the original power spectrum density of each frequency point to obtain a minimum power spectrum density of each frequency point; identifying noise points according to the frequency band of the vibrating table where each frequency point is located and the minimum power spectral density of each frequency point, and correcting the original power spectral density to obtain corrected power spectral density;
The noise control module 103 is configured to calculate a noise existence probability according to the minimum power spectral density of the noise point and the corrected power spectral density, calculate a gain of the noise point, multiply the gain of the noise point with the frequency domain signal, and perform inverse short-time fourier transform to obtain a voltage signal after noise reduction;
The signal output module 104 is configured to input the noise-reduced voltage signal and the given voltage signal into a PID controller, compare the output of the PID controller with a set triangular wave, control on-off of an IGBT bridge arm in a power amplifier of the vibration table, and output a voltage signal.
Because the relevant parts of the power amplification noise control device of the vibrating table and the power amplification noise control method of the vibrating table in this embodiment can be referred to each other, the description is repeated here, and therefore, the description is not repeated here. The principle of the embodiment of the device is the same as that of the embodiment of the method, so the embodiment of the device also has the corresponding technical effects of the embodiment of the method.
Those skilled in the art will appreciate that all or part of the flow of the methods of the embodiments described above may be accomplished by way of a computer program to instruct associated hardware, where the program may be stored on a computer readable storage medium. Wherein the computer readable storage medium is a magnetic disk, an optical disk, a read-only memory or a random access memory, etc.
The present invention is not limited to the above-mentioned embodiments, and any changes or substitutions that can be easily understood by those skilled in the art within the technical scope of the present invention are intended to be included in the scope of the present invention.
Claims (10)
1. The power amplification noise control method of the vibrating table is characterized by comprising the following steps of:
Performing short-time Fourier transform on the voltage signal output by the power amplifier of the vibrating table to obtain a frequency domain signal, and calculating the original power spectrum density of each frequency point in the frequency domain signal;
Performing bidirectional search on the original power spectrum density of each frequency point to obtain the minimum power spectrum density of each frequency point; identifying noise points according to the frequency band of the vibrating table where each frequency point is located and the minimum power spectral density of each frequency point, and correcting the original power spectral density to obtain corrected power spectral density;
Calculating the noise existence probability according to the minimum power spectral density of the noise point and the corrected power spectral density, calculating the gain of the noise point, multiplying the gain of the noise point with the frequency domain signal, and then performing inverse short-time Fourier transform to obtain a voltage signal after noise reduction;
And inputting the noise-reduced voltage signal and the voltage given signal into a PID controller, comparing the output of the PID controller with the set triangular wave, controlling the on-off of the IGBT bridge arm in the power amplifier of the vibrating table, and outputting the voltage signal.
2. The method for controlling noise of a power amplifier of a vibrating table according to claim 1, wherein the bi-directionally searching the original power spectral density of each frequency point to obtain the minimum power spectral density of each frequency point comprises: sequentially taking each frequency point as a center, respectively expanding the frequency bands backwards and forwards according to a preset frame number, and taking the minimum power spectral density in the two expanded frequency bands as a first spectral density and a second spectral density; and taking the maximum value of the first spectral density and the second spectral density as the minimum power spectral density of the current frequency point.
3. The method of claim 1, wherein the frequency bands of the vibration table include an in-band frequency range, an out-of-band frequency range, and a sampling frequency range, each frequency band corresponding to a noise spectrum threshold.
4. A method for controlling noise of a power amplifier of a vibrating table according to claim 3, wherein the identifying the noise point according to the frequency band of the vibrating table where each frequency point is located and the minimum power spectral density of each frequency point comprises:
Taking the ratio of the original power spectral density to the minimum power spectral density of each frequency point as noise spectral quantity, and acquiring a corresponding noise spectral threshold value according to the frequency band of the vibrating table where each frequency point is positioned as a comparison threshold value; and taking the frequency points with the noise spectrum quantity larger than the comparison threshold value as noise points.
5. The method for controlling noise of a power amplifier of a vibrating table according to claim 2, wherein the estimating and correcting the original power spectral density to obtain the corrected power spectral density includes:
according to the ratio of the first spectral density to the second spectral density of each frequency point, obtaining the spectral density variation of each frequency point, and comparing the spectral density variation with a preset variation threshold value:
when the spectral density variation is smaller than the variation threshold, directly taking the minimum power spectral density of the frequency point as the corrected power spectral density of the frequency point;
when the spectral density variation is greater than or equal to the variation threshold, if the frequency point is not a noise point, the power spectral density of the frequency point is unchanged, and if the frequency point is a noise point, the power spectral density corrected by the frequency point before the frequency point is taken as the power spectral density corrected by the frequency point.
6. The method of claim 5, wherein the corrected power spectral density is normalized by a ratio of a number of sampling instants in a frame of signal to an oversampling rate.
7. The method for controlling noise of a power amplifier of a vibrating table according to claim 1, wherein the noise existence probability is calculated according to the minimum power spectral density and the corrected power spectral density of the noise point by the following formula:
Where P (f z, k) represents the noise existence probability of the noise point f z at the sampling time k, ω (f z, k) represents the power spectral density after correction of the noise point f z, C min(fz, k) represents the minimum power spectral density of the noise point f z, θ represents the noise probability threshold, and β represents the scaling factor.
8. The method for controlling noise of a power amplifier of a vibrating table according to claim 7, wherein the gain of the noise point is calculated by the following formula:
Where G y(fz, k) represents the gain of noise point f z at sample time k, Indicating the conditional gain in the presence of noise, G min indicates the lower gain limit.
9. The method of claim 8, wherein the conditional gain when noise is present is calculated by using a noise existence probability by the following formula:
10. A vibrating table power amplifier noise control device, comprising:
The signal acquisition module is used for carrying out short-time Fourier transform on the voltage signal output by the power amplifier of the vibrating table to obtain a frequency domain signal, and calculating the original power spectral density of each frequency point in the frequency domain signal;
The noise analysis module is used for carrying out bidirectional search on the original power spectral density of each frequency point to obtain the minimum power spectral density of each frequency point; identifying noise points according to the frequency band of the vibrating table where each frequency point is located and the minimum power spectral density of each frequency point, and correcting the original power spectral density to obtain corrected power spectral density;
The noise control module is used for calculating the noise existence probability according to the minimum power spectral density of the noise point and the corrected power spectral density, calculating the gain of the noise point, multiplying the gain of the noise point with the frequency domain signal, and then performing inverse short-time Fourier transform to obtain a voltage signal after noise reduction;
the signal output module is used for inputting the noise-reduced voltage signal and the voltage given signal into the PID controller, comparing the output of the PID controller with the set triangular wave, controlling the on-off of the IGBT bridge arm in the power amplifier of the vibrating table and outputting the voltage signal.
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