CN103913271B - Method for extracting dynamic unbalance signals of rotor at non-stable rotational speed - Google Patents
Method for extracting dynamic unbalance signals of rotor at non-stable rotational speed Download PDFInfo
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- CN103913271B CN103913271B CN201410052317.XA CN201410052317A CN103913271B CN 103913271 B CN103913271 B CN 103913271B CN 201410052317 A CN201410052317 A CN 201410052317A CN 103913271 B CN103913271 B CN 103913271B
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Abstract
The invention provides a method for extracting dynamic unbalance signals of a rotor at a non-stable rotational speed and relates to the technical field of electronic measurement. The method includes the steps of estimating instantaneous frequency, filtering vibration signals, carrying out unrelated processing on the rotational speed, and extracting the amplitude A and the phase position phi of the unbalanced signals. From theoretical analysis to verification of the embodiment, the method has the advantages of being simple in process, simple in system arrangement, obvious in effect, easy to apply and popularize in projects and the like.
Description
Technical field
The present invention relates to electronic measuring technology field, refer specifically to a kind of non-stationary speed conditions lower rotor part unbalance dynamic signal
Extracting method.
Background technology
No matter being the offline balance of rotor, field balancing, or Automatic Balancing Technique of Rotor, accurately extract uneven by rotor
Weighing the vibration signal causing is all the key link improving balance quality, and the measurement of conventional rotors amount of unbalance assumes that and turns
Carry out in the case that speed is constant, rotor oscillation now is stationary signal, using the vibration of constant duration sampling complete cycle
Data, carries out amplitude and phase place that the methods such as Fourier transform or correlation analysiss obtain rotor unbalance signal.But it is real in engineering
In trampling, rotor speed fluctuation or speed-varying rotor be a large amount of exist, when rotor acceleration is relatively low, damping is larger and rotor speed not
In resonance region, the response being caused by rotor tangential acceleration will little be obtained compared with the vibratory response being caused by rotor unbalance value
Many, occupying an leading position of the unbalance response of rotor, now still amount of unbalance can be obtained by once per revolution vibration signal.But
Under non-stationary speed conditions, the instantaneous frequency of once per revolution vibration signal and instantaneous amplitude are all instance variable（Vibration amplitude and frequency
Square it is directly proportional）, therefore Fourier transform or correlation analysiss etc. are carried out using traditional constant duration sampled data and obtain not
The amplitude of balanced signal and phase place, can produce larger error.At present, most dynamic balancing measurements require relatively steady in rotating speed
Carry out under conditions of fixed, when rotating speed has little fluctuation, generally vibration signal now is approximately stationary signal and processes, to survey
The precision and stability of amount brings detrimental effect.
In rotor dynamic balancing measuring system, generally it is used for producing key signal and measurement rotating speed using photoelectric sensor,
Because only producing a pulse weekly, the mean speed in several weeks or a week can only be measured, instantaneous change in a week for the rotor speed
Change cannot measure, and when the fluctuation of speed, rotor is jiggly completing during a transhipment is moved in time domain, according to every turn
Interior transient speed carries out rotating speed unrelatedization and processes to vibration signal, then adopts method of least square to identify the width of unbalanced signal
Value and phase place, the method can overcome the impact of the fluctuation of speed.If the wink in every turn of rotor can be obtained using photoelectric code disk
When rotating speed, but hardware cost can be increased, and bring the deuce to pay to installation, be not suitable for engineer applied.There is document（《Electromechanical engineering》
02nd phase in 2011）" the rotor oscillation signal equiphase complete cycle sampling control method based on FPGA ", proposes to adopt rotating speed arteries and veins
The frequency doubling signals springs of punching are sampled and to be realized equiphase sampling, and the essence of the method is to adopt mean speed in every turn, and adopts
It is different it is impossible to fundamentally solve equiphase Sampling with the sampling of code-disc pulse-triggered.Such as document again（《Vibration, survey
Examination and diagnosis》4th phase in 2012）" weak non-stationary rotating speed lower rotor part dynamic balance method ", propose by carrying out to vibration signal
Time frequency analysis obtain rotor instantaneous frequency, although the method is feasible in theory, do not comprise using in key signal
Rotary speed information, be therefore difficult to stable, accurately extract every turn in（Short time every）Instantaneous frequency, and amount of calculation is larger,
It is poorly suited for engineer applied.
Content of the invention
It is an object of the invention to overcoming disappearance and the deficiency of prior art presence, rotor during a kind of non-stationary rotating speed is proposed
The extracting method of unbalance dynamic signal.
As is generally known, using there is one every turn key phase pulse in dynamic-balance measuring system, can be used for measuring each revolution of
Mean speed, based on this rotating speed, can quickly record the transient speed of rotor with sample interpolation technology.Meanwhile, according to wink
When rotating speed vibration signal can be carried out rotating speed unrelatedization process, and according to known instantaneous frequency construct unbalanced signal, then
Identify amplitude and the phase place of unbalance dynamic signal by method of least square.
Accordingly, during non-stationary rotating speed of the present invention rotor unbalance dynamic signal extracting method, realized (such as by four steps
Shown in accompanying drawing 1)：
First, each vibration signal sampled point is obtained using sample interpolation technology according to one every turn key phase pulse corresponding
Instantaneous frequency, is denoted as f0, f1…fM-1；
Then, using empirical mode decomposition（EMD）Original vibration signal is filtered process, filters various noises and do
Disturb, take out the intrinsic mode function representing unbalance vibration signal, discrete signal now is denoted as x (ti) (i=0,1,2 ... M-
1)；
Further according to transient speed, vibration signal is carried out with rotating speed unrelatedization to process；
Finally, unbalanced signal is constructed according to known instantaneous frequency, and unbalanced signal is identified by method of least square
Amplitude A and phase place
As described above, during non-stationary rotating speed of the present invention rotor unbalance dynamic signal extracting method, it is simple and direct to have a step, is
Bulk cargo is put simply, and effect is substantially it is easy to application in engineering.
Brief description
Fig. 1 is the extraction FB(flow block) of rotor unbalance dynamic signal during non-stationary rotating speed of the present invention；
Fig. 2 detects amplitude and the phase-contrast curve chart of unbalanced signal for two methods of the present invention（SNR=30）；
Fig. 3 detects amplitude and the phase-contrast curve chart of unbalanced signal for two methods of the present invention（SNR=10）；
Fig. 4 measures amount of unbalance Comparative result figure for two methods of the present invention.
Specific embodiment
Below in conjunction with drawings and Examples, the invention will be further described
The extracting method of rotor unbalance dynamic signal during non-stationary rotating speed of the present invention, main inclusion：The estimation of instantaneous frequency,
The filtering of vibration signal, rotating speed unrelatedization is processed, equiphase resampling, extracts unbalanced signal amplitude A and phase place
Concrete methods of realizing：
First, the estimation of instantaneous frequency
If the average frequency in every turn of the rotor being recorded by key phase pulse is f0, f1…fk-1, wherein k turns over for rotor
Revolution, the corresponding time is TK.Vibration signal sample frequency is fs(fs=1/Ts), in TKInterior sampling number is M, due to rotating speed
It is instantaneous change, the corresponding instantaneous frequency of each sampled point is different, is obtained, be denoted as by way of cubic spline interpolation
if0, if1…ifM-1.
Comprise the following steps that：
1）According to sample frequency fsConstant duration sampling is carried out to vibration signal, each sampling instant t respectively0, t1…
tM-1；
2）Calculate each revolution of rotor rotation frequency f according to several continuous key phase pulses0, f1…fk-1, and determine and every turn frequency
In the corresponding moment, it is denoted as tt0, tt1…ttk-1, here corresponding for two neighboring rising edge of a pulse centre position sampling instant is made
For f0, f1…fk-1The corresponding moment；
3）With (tt0, f0), (tt1, f1)…(ttk-1, fk-1) based on, obtain M using cubic spline interpolation method and adopt
Sampling point corresponding instantaneous frequency (t0, if0), (t1, if1)…(tM-1, ifM-1).
Cubic spline interpolation is avoided deficient slickness and is vibrated with violent, has the advantages that high precision, flatness are good, and calculates
Amount is little, it is easy to accomplish.
2nd, the vibration signal filtering method based on EMD
It is a kind of self-adaptation nonlinear time varying signal decomposition method of data-driven.Main thought is time serieses
Signal pass through empirical mode decomposition, be expressed as the intrinsic mode function (IMF) of different time scales.Wherein, intrinsic mode letter
Number must is fulfilled for following 2 conditions：
(1) this Function Extreme Value point and zero passage count out required equal or at most mutually almost.
(2) envelope that the envelope being made up of a little louder local pole and local minimum point are constituted meansigma methodss in arbitrfary point etc.
In zero.
Further, this algorithm to realize step as follows：
1）, calculate whole Local Extremum of vibration signal x [n]；
2）Obtain the lower extreme point that the coenvelope line of all maximum points compositions and all minimum points are constituted, be denoted as respectively
emax[n] and emin[n]；
3）Calculate the average of upper and lower envelope, be denoted asAnd ask signal and this average
Difference, be denoted as d [n]=x [n]-m [n]；
4）Judge whether d [n] meets the two attributes of above-mentioned IMF, if meeting, d [n] is IMF；Otherwise, note d [n] is x
[n], repeat the above steps 1）～3）, until obtaining an IMF, it is denoted as IMF1[n]；
5）Note r1[n]=x[n]-IMF1[n] is new signal to be decomposed, repeats 1）～4）Step obtains second IMF, note
Make IMF2[n].Steps be repeated alternatively until rN[n] is monotonic signal or rN[n] is less than default threshold value, and decomposition terminates.
Primary signal can be expressed as,
According to EMD algorithm, the corresponding IMF of unbalanced signal can be extracted from containing noisy signal.
3rd, rotating speed unrelatedization is processed
According to transient speed, vibration signal is carried out with rotating speed unrelatedization to process it is assumed that passing through the filtered vibration signal of EMD
For x (ti) (i=0,1,2 ... M-1), the corresponding instantaneous frequency of each sampled point is if0, if1…ifM-1, for overcoming rotating speed to vibration
After rotating speed unrelatedization of the impact of amplitude is processed, vibration signal is：
4th, unbalance dynamic signal amplitude A and phase placeExtraction
Corresponding instantaneous frequency if of each sampled point is estimated according to key phase pulse0, if1…ifM-1Afterwards, frequency can be constructed
Known to rate, unbalanced signal is as follows：
Wherein A is unbalanced signal amplitude,Phase place for unbalanced signal.
Above formula can transform to
WhereinThe two is parameter to be estimated, above-mentioned EMD is filtered and turns
The vibration signal that fast unrelatedization was processed is as observation x ' (ti), i=0,1,2 ... M-1, the system of linear equations that can draw
Asking its least square solution can pick out parameter is y1, y2.Then the estimated value of amplitude and phase place is
Emulation and experimental result：
Emulation and interpretation of result
Constructive simulation signal is made up of with noise signal slow change of frequency, that is,
In formula, n (t) is noise signal, frequency f=5+0.5 × t2.
TakeDuring fs=1000, survey secondary frequencies in each cycle, extract the width of signal using two methods respectively
Value and phase place：（1）Traditional method, that is, suppose each cycle in rotating speed constant, the amplitude of signal and phase are extracted using FFT method
Position；（2）Method proposed by the present invention, that is, the frequency according to measurement in each cycle, obtains instantaneous frequency by the way of interpolation,
Then do rotating speed unrelatedization to process, finally adopt method of least square to identify amplitude and the phase place of unbalanced signal.In signal to noise ratio snr
When taking 30 and 10 respectively, do the amplitude of 10 unbalanced signals and the extraction of phase place, result such as accompanying drawing 2 respectively using two methods
With shown in accompanying drawing 3.10 measurement mean absolute errors of two methods（MAE）As shown in table 1.
Two methods of the unbalanced signal of table 1 extracts MAE contrast
It can be seen that, even if in less signal to noise ratio, the amplitude mean error of the unbalanced signal that the method for the present invention is extracted is excellent
In 1%, the mean error of phase place is within 1 °.Therefore, using unbalanced signal phase place proposed by the present invention extraction accuracy and
Stability is all obviously improved, and the extraction accuracy of amplitude slightly improves.
Experiment and interpretation of result
Using the dynamic balancing frame of 6Ton, AC inverter driving system, rotor length is 7 meters for experiment, and radius is 0.18 meter.Pass through
The setpoint frequency changing converter, to change rotor speed, rotary speed setting value is adjusted to 300rpm from 250rpm, rises in rotating speed
During be respectively adopted traditional FFT method and the inventive method continuously measures amount of unbalance 5 times, then by rotary speed setting value from
300rpm is adjusted to 250rpm, is respectively adopted the continuous measurement of two methods 5 times.
When placing 50g test mass 90 degree of positions, during according to above-mentioned rotation speed change, it is respectively adopted traditional FFT method and basis
10 measurement results of inventive method are as shown in Figure 4.The method of the present invention compared with traditional method, repeatedly measure when, phase place
Stability have larger improvement, phase fluctuation is substantially within 2 °；The stability of amplitude is slightly improved.One of the reason improve be
Instantaneous frequency is introduced into unbalanced signal and extracts the impact reducing the fluctuation of speed in computing；EMD filtering algorithm is also had effectively to filter
Except noise signal.The present embodiment is slower because of the rotation speed change of this rotor, and therefore effect is not too obvious, but for small-sized turn
Son, when the fluctuation of speed is slightly larger, can become apparent from the effect of prominent the method.This experiment is substantially identical with the result of above-mentioned emulation.
In sum, during non-stationary rotating speed of the present invention rotor unbalance dynamic signal extracting method, from theory analysis to reality
Apply the checking of example, illustrate that the present invention has a step simple and direct, system and device is simple, effect is substantially it is easy to application etc. in engineering
Feature.
Claims (1)
1. during a kind of non-stationary rotating speed the extracting method of rotor unbalance dynamic signal it is characterised in that by step：
A. the estimation of instantaneous frequency；B. the filtering of vibration signal；C. rotating speed unrelatedization is carried out to vibration signal according to instantaneous frequency
Process；D. the extraction composition of unbalanced signal amplitude and phase place；
Described step A. by key phase pulse obtain every turn in mean speed, using cubic spline interpolation obtain every turn in instantaneous
Frequency estimation, including step：
The each revolution of frequency of rotor being recorded by key phase pulse is denoted as f0, f1…fk-1；
Wherein, the revolution that k turns over for rotor, every turn of corresponding moment is denoted as tt0, tt1…ttk-1；
Set k and turn required time as TK, vibration signal sample frequency isWhen, TKInterior sampling number is M, corresponding
M sampling instant be denoted as t0, t1…tM-1；
With (tt0, f0), (tt1, f1)…(ttk-1, fk-1) based on, obtain (t by way of cubic spline interpolation0, if0),
(t1, if1)…(tM-1, ifM-1), that is, the corresponding instantaneous frequency of M point is if0, if1…ifM-1；
Described step B. is filtered to original vibration signal processing using empirical mode decomposition (EMD), filters various noises and does
Disturb, isolate the intrinsic mode function representing unbalance vibration signal, the discrete signal setting now is denoted as x (ti) i=0,1,
2…；
Described step C. rotating speed unrelatedization is processed, including:The hypothesis filtered vibration signal of EMD is x (ti) i=0,1,2 ... M-1,
The corresponding instantaneous frequency of each sampled point is if0, if1…ifM-1, for overcoming rotating speed unrelatedization of the impact to vibration amplitude for the rotating speed
After process, vibration signal is：
Described step D. unbalanced signal amplitude and phase extraction, construct unbalanced signal according to instantaneous Frequency Estimation value firstThen intercept EMD filtering at key phase rising edge of a pulse and rotating speed unrelatedization is processed
Vibration data afterwards, as sample, identifies amplitude A and the phase place of unbalanced signal using method of least square
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| CN104101465B (en) * | 2014-08-05 | 2016-08-17 | 上海交通大学 | The channel frequency characteristic error compensation method of rotor hard bearing unbalance dynamic test |
| CN104200118A (en) * | 2014-09-15 | 2014-12-10 | 吉林大学 | Automatic balancing machine vibration signal processing method |
| CN106227909B (en) * | 2016-06-17 | 2019-09-06 | 华电电力科学研究院 | A kind of primary method for eliminating rotor of turbogenerator set Dynamic flexural |
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|---|---|---|---|---|
| US4007630A (en) * | 1974-07-12 | 1977-02-15 | Nippon Seiko K.K. | Device for detecting damage on rotators |
| CN102353500A (en) * | 2011-06-03 | 2012-02-15 | 上海师范大学 | Extraction method of unbalanced signal for dynamic balance measurement |
| CN103335785A (en) * | 2013-06-24 | 2013-10-02 | 西安交通大学 | Unsteady dynamic balance method based on order domain-holographic spectrum principle |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| US5511422A (en) * | 1993-04-09 | 1996-04-30 | Monitoring Technology Corporation | Method and apparatus for analyzing and detecting faults in bearings and other rotating components that slip |
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4007630A (en) * | 1974-07-12 | 1977-02-15 | Nippon Seiko K.K. | Device for detecting damage on rotators |
| CN102353500A (en) * | 2011-06-03 | 2012-02-15 | 上海师范大学 | Extraction method of unbalanced signal for dynamic balance measurement |
| CN103335785A (en) * | 2013-06-24 | 2013-10-02 | 西安交通大学 | Unsteady dynamic balance method based on order domain-holographic spectrum principle |
Non-Patent Citations (1)
| Title |
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| 弱非平稳转速下转子动平衡方法;纪跃波;《振动、测试与诊断》;20120831;第34卷(第4期);第597-601页 * |
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