CN106895971A - A kind of method for measuring slender axles rotor internal damping - Google Patents

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

A kind of method for measuring slender axles rotor internal damping

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 X_OUTAnd Y_OUT, the signal of collection is respectively through LPF electricity Amplifying circuit, output voltage U are accessed with differential form behind road_OUT。X_OUTAnd Y_OUTIt is the primary signal of vibrating sensor collection, U_OUT It is the voltage signal of output, is directly connected into oscillograph.

B () oscillograph is by voltage signal U_OUTProcessed, be processed into the cycle as T_dCosine signal, can measure remaining The peak value of string signal, and modal frequency ω_nDirectly 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 U_{dB_i}And correspondence Time T_iAnd i+1 cycle maximum mode amplitude U_{dB_i+1}With correspondence time T_i+1, determine i-th cycle maximum mode amplitude U_{dB_i}With i+1 cycle maximum mode amplitude U_{dB_i+1}Difference absolute value be Δ U_dB, and be shown below：

ΔU_dB=| U_{dB_i}-U_{dB_i+1}|

Wherein i=1,2,3 ... ..., N, N are oscillograph sampling number, i-th cycle maximum original mode amplitude U_i, i.e., Do not entered the maximum voltage peak value in i-th cycle of oscillograph treatment, can be represented by the formula：

20lgU_i=U_{dB_i}

Wherein i+1 cycle maximum original mode amplitude U_i+1, that is, do not entered the i+1 cycle of oscillograph treatment Maximum voltage peak value, can be represented by the formula：

20lgU_i+1=U_{dB_i+1}

Wherein：T_dIt is the time difference between two peak values, be i.e. in the cosine signal cycle, can be represented by the formula：

T_d=T_i+1-T_i

C Δ U that () measures_dB=| U_{dB_i}-U_{dB_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；ω_nIt is modal frequency；t_iIt is the time；θ is impulse response Phase angle.

I-th cycle maximum original mode amplitude U_i, it is shown below：

I+1 cycle maximum original mode amplitude U_i+1, it is shown below：

By U_iAnd U_i+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 Y_OUTIt 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 U_OUTSynthesis treatment is carried out, be can obtain with week Phase is T_dCan maximum original mode amplitude U measured directly_i, and on the basis of original value, follow-up measurement for convenience Calculate, by raw voltage values U_iIt is converted into the value U in units of decibel for being easy to measurement_{dB_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 U_OUTProcessed, the cosine signal in units of decibel is formed, by showing Ripple device direct measurement draws the difference absolute value delta U of adjacent peak_dBAnd cycle T_d, the Δ U for measuring_dBAnd T_dAlgorithm 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 X_OUTAnd Y_OUTRespectively 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, R_FILTRepresent 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 ADXL203_FILTIt 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.X_OUTAnd Y_OUTAfter 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 U_OUTIt 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. 6_OUTProcessed, be processed into cosine signal, The peak value of cosine signal, and modal frequency ω can be measured_nDirectly 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 U_{dB_i}With correspondence time T_iAnd i+1 cycle maximum mode amplitude U_{dB_i+1}With correspondence time T_i+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 oscillograph_{dB_1}With correspondence time T₁And the 2nd Individual cycle maximum mode amplitude U_{dB_2}With correspondence time T₂, determine the 1st cycle maximum mode amplitude U_{dB_1}With the 2nd cycle most Big mode amplitude U_{dB_2}Difference absolute value be Δ U_dB, and be shown below：

ΔU_dB=| U_{dB_1}-U_{dB_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=U_{dB_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=U_{dB_2}

Wherein T_dIt is the time difference between two peak values, be i.e. in the cosine signal cycle, can be represented by the formula：

T_d=T₂-T₁

U is thus understood by Fig. 4 and Fig. 5_{dB_1}、U_{dB_2}、T₁、T₂And ω_nRespectively 13.8dB V, 25.1dB V, 10ms, 110ms and 818Hz.

C Δ U that () measures_dB=| U_{dB_1}-U_{dB_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；ω_nIt 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；ω_nIt 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 U_{dB_1}=13.8dBV, U_{dB_2}=25.1dBV, T₁=10ms, T₂=110ms and ω_n=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 X_OUTAnd Y_OUT, after the signal of collection is respectively through low-pass filter circuit Amplifying circuit, output voltage U are accessed with differential form_OUT, X_OUTAnd Y_OUTIt is the primary signal of vibrating sensor collection, U_OUTFor defeated The voltage signal for going out, is directly connected into oscillograph；

B () oscillograph is by voltage signal U_OUTProcessed, be processed into the cycle as T_dCosine signal, cosine signal can be measured Peak value, and modal frequency ω_nDirectly 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 oscillograph_{dB_i}With correspondence time T_i And i+1 cycle maximum mode amplitude U_{dB_i+1}With correspondence time T_i+1, determine i-th cycle maximum mode amplitude U_{dB_i}With I+1 cycle maximum mode amplitude U_{dB_i+1}Difference absolute value be Δ U_dB, and be shown below：

ΔU_dB=| U_{dB_i}-U_{dB_i+1}|

Wherein i=1,2,3 ... ..., N, N are oscillograph sampling number, i-th cycle maximum original mode amplitude U_i, that is, do not entered The maximum voltage peak value in i-th cycle of oscillograph treatment, can be represented by the formula：

20lgU_i=U_{dB_i}

Wherein i+1 cycle maximum original mode amplitude U_i+1, that is, do not entered the maximum in the i+1 cycle of oscillograph treatment Voltage peak, can be represented by the formula：

20lgU_i+1=U_{dB_i+1}

Wherein：T_dIt is the time difference between two peak values, be i.e. in the cosine signal cycle, can be represented by the formula：

T_d=T_i+1-T_i

C Δ U that () measures_dB=| U_{dB_i}-U_{dB_i+1}| by following algorithmic formula, can directly obtain internal damping, rotor impulse response It is as follows：

$S\left(t_i\right)={\mathrm{Ae}}^{-{\mathrm{\ζ\ω}}_{n}t}sin({\mathrm{\ω}}_d{t}_i+\mathrm{\θ})$

Wherein：A is impulse response amplitude；ζ is rotor internal damping；ω_nIt is modal frequency；t_iIt is the time；θ is the phase of impulse response Parallactic angle；

I-th cycle maximum original mode amplitude U_i, it is shown below：

$U_i={\mathrm{Ae}}^{-{\mathrm{\ζ\ω}}_n{T}_i}$

I+1 cycle maximum original mode amplitude U_i+1, it is shown below：

$U_{i+1}={\mathrm{Ae}}^{-{\mathrm{\ζ\ω}}_n{T}_{i+1}}$

By U_iAnd U_i+1Compared to can obtain：

$\frac{U_i}{U_{i+1}}=e^{{\mathrm{\ζ\ω}}_n{T}_d}$

Both sides are taken the logarithm can be obtained：

${\mathrm{\ζ\ω}}_n{T}_d=ln\left(\frac{U_i}{U_{i+1}}\right)=\ln U_i-\ln U_{i+1}$

Abbreviation above formula can be obtained：

${\mathrm{\ζ\ω}}_n{T}_d=\frac{{\mathrm{\ΔU}}_{dB}}{20}ln10$

I.e.：

$\mathrm{\ζ}=\frac{{\mathrm{\ΔU}}_{dB}}{20{\mathrm{\ω}}_n{T}_d}ln10.$

2. it is according to claim 1 measurement slender axles rotor internal damping method, it is characterised in that：In the step (a) X_OUTAnd Y_OUTIt 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) U_OUTIt is modulate circuit output valve, oscillograph is to U_OUTSynthesis treatment is carried out, be can obtain with the cycle as T_dCan be measured directly Maximum original mode amplitude U_i, and on the basis of original value, follow-up survey calculation for convenience, by raw voltage values U_i It is converted into the value U in units of decibel for being easy to measurement_{dB_i}。