CN106895971A - A kind of method for measuring slender axles rotor internal damping - Google Patents
A kind of method for measuring slender axles rotor internal damping Download PDFInfo
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- CN106895971A CN106895971A CN201710235214.0A CN201710235214A CN106895971A CN 106895971 A CN106895971 A CN 106895971A CN 201710235214 A CN201710235214 A CN 201710235214A CN 106895971 A CN106895971 A CN 106895971A
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- G—PHYSICS
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Abstract
The present invention relates to a kind of method for measuring slender axles rotor internal damping, slender axles rotor static horizontal is placed on testing stand, vibration acceleration sensor is mounted on rotor surface, hammer the static rotor of horizontal positioned, vibration signal is measured by vibration acceleration sensor, signal after filtering, amplify after, then by obtaining rotor mode amplitude after oscillograph treatment, then rotor internal damping be can accurately measure out by specific algorithm.The method is simple to operate, easily realizes, provides great convenience to measurement slender axles rotor internal damping, and improve the precision and efficiency of measurement rotor internal damping.
Description
Technical field
The present invention relates to a kind of method for measuring rotor internal damping, more particularly in a kind of accurate measurement slender axles rotor
The method of damping.
Background technology
Magnetic suspension motor technology reaches its maturity, its application also more and more extensively, such as in the magnetcisuspension of aerospace field
Suspension flywheel, magnetic suspension control torque gyroscope, high-energy-density motor in the industrial production, in the magnetic suspension in clean energy resource field
Air compressor, molecular pump etc..Magnetic suspension motor can have rotating speed high, contactless, nothing to rub extensively using it is primarily due to
The advantages of wiping, long service life, key technology is to employ slender axles control supporting rotor high speed steady running.Thus slender axles
Rotor is particularly important in the entire system, and the parameters of accurate measurement rotor are critically important, for the stabilization of whole system
Property, security and economy all produce significant impact.
At present, rotor internal damping is measured, mainly there is half-power bandwidth method, amendment half-power bandwidth method and mode to be fitted
Method.Because half-power bandwidth method and amendment half-power bandwidth method are carried out in frequency domain, it is necessary to carry out FFT, energy leakage without
Method is avoided, and causes the precision of influence measurement rotor internal damping.Mode fitting process needs good condition of work simultaneously, such as encourage
Sufficient condition, good signal to noise ratio, enough frequency resolutions, also, mode fitting process performance difficulty, there is very high to equipment
It is required that.
The content of the invention
Technology solve problem of the invention is:Overcome the deficiencies in the prior art, using vibration acceleration sensor, then pass through
The analyzing and processing of oscillograph, improves the precision and efficiency of measurement slender axles rotor internal damping, and reduces method implementation
Difficulty.
Technical solution of the invention is:A kind of method for measuring slender axles rotor internal damping, comprises the following steps:
A slender axles rotor that () hammering quiescent levels are placed, is mounted on the vibration acceleration sensor detection of rotor surface
To vibration signal, collection vibration acceleration sensor output signal XOUTAnd YOUT, the signal of collection is respectively through LPF electricity
Amplifying circuit, output voltage U are accessed with differential form behind roadOUT。XOUTAnd YOUTIt is the primary signal of vibrating sensor collection, UOUT
It is the voltage signal of output, is directly connected into oscillograph.
B () oscillograph is by voltage signal UOUTProcessed, be processed into the cycle as TdCosine signal, can measure remaining
The peak value of string signal, and modal frequency ωnDirectly can be read by oscillograph, because the signal unit after oscillograph treatment is
DBV, will voltage signal be converted into dB signal, thus, read i-th cycle of oscillograph maximum mode amplitude UdB_iAnd correspondence
Time TiAnd i+1 cycle maximum mode amplitude UdB_i+1With correspondence time Ti+1, determine i-th cycle maximum mode amplitude
UdB_iWith i+1 cycle maximum mode amplitude UdB_i+1Difference absolute value be Δ UdB, and be shown below:
ΔUdB=| UdB_i-UdB_i+1|
Wherein i=1,2,3 ... ..., N, N are oscillograph sampling number, i-th cycle maximum original mode amplitude Ui, i.e.,
Do not entered the maximum voltage peak value in i-th cycle of oscillograph treatment, can be represented by the formula:
20lgUi=UdB_i
Wherein i+1 cycle maximum original mode amplitude Ui+1, that is, do not entered the i+1 cycle of oscillograph treatment
Maximum voltage peak value, can be represented by the formula:
20lgUi+1=UdB_i+1
Wherein:TdIt is the time difference between two peak values, be i.e. in the cosine signal cycle, can be represented by the formula:
Td=Ti+1-Ti
C Δ U that () measuresdB=| UdB_i-UdB_i+1| by following algorithmic formula, can directly obtain internal damping formula as follows:
Rotor impulse response is as follows:
Wherein:A is impulse response amplitude;ζ is rotor internal damping;ωnIt is modal frequency;tiIt is the time;θ is impulse response
Phase angle.
I-th cycle maximum original mode amplitude Ui, it is shown below:
I+1 cycle maximum original mode amplitude Ui+1, it is shown below:
By UiAnd Ui+1Compared to can obtain:
Both sides are taken the logarithm can be obtained:
Abbreviation above formula can be obtained:
I.e.:
X in the step (a)OUTAnd YOUTIt is raw voltage values, by that can realize removing signal after filter circuit
Tooth pitch and noise attenuation, noise floor density is reduced by filtering, and improves certainty of measurement, and the present invention uses vibration acceleration to sense
Device model ADXL203, the representative value of its output signal bandwidth is 2.5kHz, and signal is filtered, and can effectively prevent frequency
Rate aliasing.ADXL203 can according to actual needs change filter capacitor C2To set output signal bandwidth, signal bandwidth is smaller,
Noise is smaller, thus precision is higher.
U in the step (b)OUTIt is modulate circuit output valve, oscillograph is to UOUTSynthesis treatment is carried out, be can obtain with week
Phase is TdCan maximum original mode amplitude U measured directlyi, and on the basis of original value, follow-up measurement for convenience
Calculate, by raw voltage values UiIt is converted into the value U in units of decibel for being easy to measurementdB_i。
Principle of the invention is:Vibration acceleration sensor ADXL203 is output as continuous signal, can be thin with gamut reaction
The amplitude response of long-shaft rotor, two axis signals of output are realized removing tooth pitch and noise attenuation respectively through filter circuit, so subtract
Few noise floor density, improves certainty of measurement, and two groups of signals access amplifying circuit in a differential manner, are amplified to signal and are beneficial to
Oscillograph Treatment Analysis scope, oscillograph is by signal UOUTProcessed, the cosine signal in units of decibel is formed, by showing
Ripple device direct measurement draws the difference absolute value delta U of adjacent peakdBAnd cycle Td, the Δ U for measuringdBAnd TdAlgorithm can be brought directly to public
In formula, slender axles rotor internal damping ζ is finally drawn.
Present invention advantage compared with prior art is:
(1) method of the measurement slender axles rotor internal damping that the present invention is proposed, it is simple to operate, it is easy to accomplish, it is applicable
In most of occasions, modulate circuit can flexible modulation output area, improve the precision of vibration acceleration sensor signal condition
And efficiency.
(2) the method applied in the present invention only needs to just can accurately measure rotor internal damping by oscillograph, without a large amount of
Work, workload is small.
Brief description of the drawings
Fig. 1 is present system flow chart;
Fig. 2 is slender axles rotor and vibration acceleration sensor position relationship schematic diagram;
Fig. 3 is system organization connection figure;
Fig. 4 is T1Oscillograph work sheet under moment;
Fig. 5 is T2Oscillograph work sheet under moment;
Fig. 6 is vibration acceleration sensor modulate circuit figure.
Specific embodiment
As shown in Fig. 1,2,3,4,5,6, specific method of the invention is as follows:
A () as shown in Fig. 2, Fig. 3, Fig. 6, Fig. 2 is mounted on rotor surface schematic diagram for vibration acceleration sensor, Fig. 3 is
System organization connection figure, i.e. sensor, the connection figure between modulate circuit and oscillograph, Fig. 6 are adjusted for vibration acceleration sensor
Reason circuit diagram, including filter circuit and differential amplifier circuit two parts.The slender axles rotor that hammering quiescent levels are placed, is mounted on
The vibration acceleration sensor of rotor surface detects vibration signal, vibration acceleration sensor output signal XOUTAnd YOUTRespectively
Low-pass filter circuit is accessed, uses the vibration acceleration sensor model ADXL203, the representative value of its output signal bandwidth to be
2.5kHz, is filtered to signal, can effectively prevent frequency alias.ADXL203 can change filtered electrical according to actual needs
Hold C2To set output signal bandwidth, the relation of filter capacitor and signal bandwidth is shown below:
Wherein F represents bandwidth value, RFILTRepresent the internal nominal resistance of ADXL203, C2Represent C2Capacitance.
In order that a width of 1kHz of ADXL203 output signal bands, it is known that the internal nominal resistance R of ADXL203FILTIt is 16K Ω,
We are by electric capacity C2Size determine in 0.01 μ F.The typical output valve of ADXL203 is 0.15V, thus will respectively to two letters
Number access amplifying circuit makes envelope eapsulotomy, and magnification ratio is 4.XOUTAnd YOUTAfter filtering after amplifying circuit, then with differential form
Access ratio is 5 amplifying circuit, and differential form can improve the precision of whole system, finally by reasonable arrange parameter, can be by
Output signal UOUTIt is transferred in the range of 0~3V, to facilitate oscillograph to read and analyze and process.
B () as shown in Figure 4, Figure 5, figure is oscillograph by voltage signal U in Fig. 6OUTProcessed, be processed into cosine signal,
The peak value of cosine signal, and modal frequency ω can be measurednDirectly can be read by oscillograph, because after oscillograph treatment
Signal unit is dBV, will voltage signal be converted into dB signal.Thus, read i-th cycle maximum mode amplitude of oscillograph
UdB_iWith correspondence time TiAnd i+1 cycle maximum mode amplitude UdB_i+1With correspondence time Ti+1.As shown in Figure 4 and Figure 5,
We take the 1st and the 2nd cycle, read the 1st cycle maximum mode amplitude U of oscillographdB_1With correspondence time T1And the 2nd
Individual cycle maximum mode amplitude UdB_2With correspondence time T2, determine the 1st cycle maximum mode amplitude UdB_1With the 2nd cycle most
Big mode amplitude UdB_2Difference absolute value be Δ UdB, and be shown below:
ΔUdB=| UdB_1-UdB_2|
Wherein the 1st cycle maximum original mode amplitude U1, that is, do not entered the maximum electricity in the 1st cycle of oscillograph treatment
Voltage crest value, can be represented by the formula:
20lgU1=UdB_1
Wherein the 2nd cycle maximum original mode amplitude U2, that is, do not entered the maximum electricity in the 2nd cycle of oscillograph treatment
Voltage crest value, can be represented by the formula:
20lgU2=UdB_2
Wherein TdIt is the time difference between two peak values, be i.e. in the cosine signal cycle, can be represented by the formula:
Td=T2-T1
U is thus understood by Fig. 4 and Fig. 5dB_1、UdB_2、T1、T2And ωnRespectively 13.8dB V, 25.1dB V, 10ms,
110ms and 818Hz.
C Δ U that () measuresdB=| UdB_1-UdB_2| by following algorithmic formula, can directly obtain internal damping formula as follows:
1st cycle maximum original mode amplitude U1, it is shown below:
Wherein A is impulse response amplitude;ζ is rotor internal damping;ωnIt is modal frequency.
2nd cycle maximum original mode amplitude U2, it is shown below:
Wherein A is impulse response amplitude;ζ is rotor internal damping;ωnIt is modal frequency.
By U1And U2Compared to can obtain:
Both sides are taken the logarithm can be obtained:
Abbreviation above formula can be obtained:
I.e.:
By UdB_1=13.8dBV, UdB_2=25.1dBV, T1=10ms, T2=110ms and ωn=818Hz brings into respectively
Above formula, obtains ζ=0.016062417.
The present invention can be as a kind of general measurement slender axles rotor internal damping method, and modulate circuit can be more accurately real
Existing proportion adjustment output signal, it is simple to operate, easily realize, improve the precision and effect of vibration acceleration sensor signal condition
Rate, algorithm is efficiently convenient, improves the efficiency of calculating.
Non-elaborated part of the present invention belongs to techniques well known.
Claims (4)
1. it is a kind of measure slender axles rotor internal damping method, it is characterised in that:It is achieved by the steps of:
A slender axles rotor that () hammering quiescent levels are placed, the vibration acceleration sensor for being mounted on rotor surface is detected and shaken
Dynamic signal, collection vibration acceleration sensor output signal XOUTAnd YOUT, after the signal of collection is respectively through low-pass filter circuit
Amplifying circuit, output voltage U are accessed with differential formOUT, XOUTAnd YOUTIt is the primary signal of vibrating sensor collection, UOUTFor defeated
The voltage signal for going out, is directly connected into oscillograph;
B () oscillograph is by voltage signal UOUTProcessed, be processed into the cycle as TdCosine signal, cosine signal can be measured
Peak value, and modal frequency ωnDirectly can be read by oscillograph, because the signal unit after oscillograph treatment is dBV, i.e.,
Voltage signal is converted into dB signal, thus, read i-th cycle maximum mode amplitude U of oscillographdB_iWith correspondence time Ti
And i+1 cycle maximum mode amplitude UdB_i+1With correspondence time Ti+1, determine i-th cycle maximum mode amplitude UdB_iWith
I+1 cycle maximum mode amplitude UdB_i+1Difference absolute value be Δ UdB, and be shown below:
ΔUdB=| UdB_i-UdB_i+1|
Wherein i=1,2,3 ... ..., N, N are oscillograph sampling number, i-th cycle maximum original mode amplitude Ui, that is, do not entered
The maximum voltage peak value in i-th cycle of oscillograph treatment, can be represented by the formula:
20lgUi=UdB_i
Wherein i+1 cycle maximum original mode amplitude Ui+1, that is, do not entered the maximum in the i+1 cycle of oscillograph treatment
Voltage peak, can be represented by the formula:
20lgUi+1=UdB_i+1
Wherein:TdIt is the time difference between two peak values, be i.e. in the cosine signal cycle, can be represented by the formula:
Td=Ti+1-Ti
C Δ U that () measuresdB=| UdB_i-UdB_i+1| by following algorithmic formula, can directly obtain internal damping, rotor impulse response
It is as follows:
Wherein:A is impulse response amplitude;ζ is rotor internal damping;ωnIt is modal frequency;tiIt is the time;θ is the phase of impulse response
Parallactic angle;
I-th cycle maximum original mode amplitude Ui, it is shown below:
I+1 cycle maximum original mode amplitude Ui+1, it is shown below:
By UiAnd Ui+1Compared to can obtain:
Both sides are taken the logarithm can be obtained:
Abbreviation above formula can be obtained:
I.e.:
2. it is according to claim 1 measurement slender axles rotor internal damping method, it is characterised in that:In the step (a)
XOUTAnd YOUTIt is raw voltage values, by that can realize removing tooth pitch and noise attenuation to signal after filter circuit, by filter
Ripple reduces noise floor density, improves certainty of measurement.
3. it is according to claim 1 measurement slender axles rotor internal damping method, it is characterised in that:The vibration acceleration
Sensor model number is ADXL203, and the representative value of its output signal bandwidth is 2.5kHz, and signal is filtered, and can effectively be prevented
Only frequency alias.
4. it is according to claim 1 measurement slender axles rotor internal damping method, it is characterised in that:In the step (b)
UOUTIt is modulate circuit output valve, oscillograph is to UOUTSynthesis treatment is carried out, be can obtain with the cycle as TdCan be measured directly
Maximum original mode amplitude Ui, and on the basis of original value, follow-up survey calculation for convenience, by raw voltage values Ui
It is converted into the value U in units of decibel for being easy to measurementdB_i。
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Cited By (1)
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CN109323831A (en) * | 2018-09-05 | 2019-02-12 | 哈尔滨工程大学 | A kind of elongate rotation shaft modal test device discharging advocate approach suddenly based on preload |
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2017
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CN1965214A (en) * | 2003-10-30 | 2007-05-16 | 因万西斯系统股份有限公司 | Dynamic response characteristics of flow meters |
CN204535974U (en) * | 2015-04-20 | 2015-08-05 | 中国电力科学研究院 | A kind of substation framework damper pick-up unit |
JP2017044479A (en) * | 2015-08-24 | 2017-03-02 | 株式会社明電舎 | Stability discrimination method for rotor supported by oil film bearings |
CN105277348A (en) * | 2015-10-13 | 2016-01-27 | 国家电网公司 | Method for measuring inherent frequency of stator core/support system of water turbine generator prototype |
Non-Patent Citations (1)
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CN109323831A (en) * | 2018-09-05 | 2019-02-12 | 哈尔滨工程大学 | A kind of elongate rotation shaft modal test device discharging advocate approach suddenly based on preload |
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