CN103033255B - Extraction device for relative motion capacity of low-frequency electromagnetic vibration generator system - Google Patents

Abstract

The extraction device for the relative motion of the low-frequency electromagnetic vibrating table includes a pure resistance, a first subtractor and a first proportional amplifier; the pure resistance is connected in series with the driving coil of the vibrating table, and the total voltage drop between the pure resistance and the driving coil is used as the subtrahend input. In the first subtractor described above; the voltage drop at both ends of the pure resistance is amplified K ₁ times by the first proportional amplifier as a subtrahend and input in the first subtractor described, wherein, R is the equivalent DC resistance of the driving coil of the vibrating table, and _R1 is the resistance value of pure resistance; the output signal of the first subtractor represents the relative motion speed of the vibrating table; by performing differential or integral operations on the relative motion speed, it can be obtained Relative motion acceleration or relative motion displacement of the vibrating table. The invention has the advantages of convenient realization, low cost and high accuracy of relative motion extraction.

Description

Extraction device for relative motion of low-frequency electromagnetic vibrating table

technical field

The invention relates to a device for extracting the relative motion of a low-frequency electromagnetic vibrating table, which can be used in the measurement of the relative motion of the low-frequency electromagnetic vibrating table and the control system of the low-frequency electromagnetic vibrating table based on the feedback of the relative motion.

technical background

The electromagnetic vibrating table has the advantages of wide frequency range, good controllability, and high output waveform accuracy, and is widely used in important fields such as simulated vibration environmental tests of products, vibration sensor calibration, etc. Low-frequency vibration widely exists in aerospace, building monitoring, earthquake prediction, resource exploration and other fields. With the continuous development of science and technology, people's demand for low-frequency electromagnetic vibration tables is becoming more and more urgent. In order to accurately obtain the output vibration signal of the low-frequency electromagnetic vibrating table, or to build a closed-loop control system to improve the accuracy of the output waveform of the low-frequency electromagnetic vibrating table, it is often necessary to use a low-frequency motion detection sensor to extract the output motion of the vibrating table. However, various low-frequency motion detection sensors are usually expensive, bulky, and complicated to install, which limits their wide application in low-frequency electromagnetic vibration table systems.

Contents of the invention

In order to overcome the shortcomings of various low-frequency motion detection sensors in the prior art, which are expensive, bulky, and complicated to install, the present invention provides a device capable of extracting the relative motion of a low-frequency electromagnetic vibrating table with high precision and convenience.

The device for extracting the relative motion of the low-frequency electromagnetic vibrating table includes a pure resistance, a first subtractor and a first proportional amplifier;

The pure resistance is connected in series with the drive coil of the vibrating table, and the total voltage drop between the pure resistance and the drive coil is input into the first subtractor as the subtrahend;

The voltage drop at both ends of the pure resistance is input into the first proportional amplifier, and the first proportional amplifier outputs the amplified pure resistance voltage drop, and the amplified pure resistance voltage drop is input into the first subtractor as a subtrahend; The output signal of the first subtractor represents the relative motion speed of the vibrating table;

The magnification of the first proportional amplifier Among them, R is the equivalent DC resistance of the driving coil of the vibrating table, and _R1 is the resistance value of pure resistance.

The total voltage drop between the pure resistance and the driving coil is u ₁ =(R+R ₁ )i+Li'+Blx', where L is the equivalent inductance of the driving coil of the vibrating table, B is the magnetic induction of the air gap magnetic field, and l is The winding length of the driving coil, i is the current input to the driving coil of the vibrating table, i' is the derivative of i to time, x is the displacement of the driving coil of the vibrating table relative to the installation base of the vibrating table, x' is the derivative of x to time, is the relative velocity of the vibrating table.

The voltage drop across a pure resistance is u ₂ =R ₁ i; therefore, the output signal of the first subtractor is Δu=u ₁ -K ₁ u ₂ =[R+(1-K ₁ )R ₁ ]i+Li'+ Blx'=Li'+Blx'; from the low-frequency electromagnetic vibrating table driving equation mx″+cx'+kx=Bil, the frequency characteristic equation of the system can be obtained as Then the amplitude ratio of displacement x and driving current i can be obtained The amplitude ratio of Li' and Blx' can be expressed as $\left|\frac{L\&Center\; Dot;\mathrm{j\ω}\·I\left(\mathrm{j\ω}\right)}{\mathrm{Bl}\·\mathrm{j\ω}\·x\left(\mathrm{j\ω}\right)}\right|=\frac{L}{\mathrm{Bl}}\left|\frac{I\left(\mathrm{j\ω}\right)}{x\left(\mathrm{j\ω}\right)}\right|=L\sqrt{\frac{{(k-{\mathrm{m\ω}}^2)}^2+{\left(\mathrm{c\ω}\right)}^2}{{\left(\mathrm{Bl}\right)}^2}}.$ According to the actual system parameters, under low frequency conditions, and (Bl) ² have the same order of magnitude, and L is of the order of 10 ^-3 Heng, so it can be considered that the amplitude of Li' is much smaller than that of Blx', and it can be obtained that Δu≈Blx'. In the above expression, m is the mass of the moving parts of the electromagnetic vibrating table, c and k are the damping and stiffness of the elastic supporting parts of the electromagnetic vibrating table, x " is the twice derivative of x to time, which is the relative acceleration of the vibrating table, X( jω) and I(jω) are the Fourier transforms of x and i respectively, ω is the angular frequency of vibration.

Through the technical means of optimizing the shape of the air gap, the magnetic induction intensity B of the air gap can be kept constant in the whole travel range of the shaking table, that is to say, the voltage difference signal Δu obtained by Δu=Blx' is proportional to the relative speed x' of the shaking table, The voltage difference signal Δu can characterize the relative velocity x' of the low-frequency vibrating table.

It is further defined that the first subtractor is respectively connected with the integrator or the differentiator or the second proportional amplifier, the output signal of the integrator represents the relative displacement of the vibrating table, the output signal of the differentiator represents the relative acceleration of the vibrating table, and the output signal of the second proportional amplifier The output signal is the amplified relative velocity of the shaking table.

Since the resistance of the drive coil is not easy to measure accurately, _K1 is difficult to obtain accurately through calculation and can only be determined through gradual adjustment. Further definition: the adjustment method of the _{magnification} K of the first proportional amplifier comprises the following steps:

(1) The drive coil of the vibrating table is connected in series with a pure resistor, and then a constant current I is passed through;

(2) Obtain the output signal Δu of the first subtractor,

Δu=u ₁ -K ₁ u ₂ =[R+(1-K ₁ )R ₁ ]I+LI'+Blx',

Wherein, I' is the derivative of I to time;

(3) Wait for the vibrating table to be stationary, at this time the relative speed of the vibrating table x'=0, so Blx'=0; at the same time, because the current I passed is a constant current, that is, I'=0, so LI'=0 , so that Δu=u ₁ -K ₁ u ₂ =[R+(1-K ₁ )R ₁ ]I can be calculated;

(4) Adjust K ₁ until Δu=0, at this time The adjustment is complete.

The adjustment of the magnification _K1 is carried out before the extraction test of the relative motion amount. For the specified vibration table and pure resistance, once the adjustment of _K1 is completed, it cannot be changed again.

In order to improve the adjustment accuracy of K ₁ , it is further defined that when adjusting the magnification of the first proportional amplifier, the output signal of the second proportional amplifier is used as a reference signal, and the magnification of the second proportional amplifier is K ₂ (K ₂ >1), step In (4), adjust K ₁ until K ₂ Δu=0. Since the value of K ₂ Δu is obviously greater than Δu, it is easy to monitor and can improve the adjustment accuracy of K ₁ .

The electromagnetic vibrating table is a typical electromechanical coupling system, and the mechanical movement must be reflected in the electrical link. Firstly, current is passed into the coil, and under the action of electromagnetic induction, an ampere force is generated to drive the vibrating table to move. During this process, the driving coil of the vibrating table cuts the magnetic induction line, and an induction reflecting the relative velocity of the vibrating table is generated in the coil electromotive force. By extracting the coil voltage signal, and considering that when the electromagnetic vibrating table operates under low frequency conditions, irrelevant components can be ignored or removed by a certain method, the voltage signal reflecting the relative velocity of the vibrating table can be obtained, and at the same time, the existence of The differential and integral relationship of the model can also be easily obtained; through further processing of the obtained motion, it can be used for feedback control of the low-frequency vibration table.

The invention has the advantages of convenient implementation, low cost and high accuracy of relative motion extraction.

Description of drawings

Fig. 1 is a schematic diagram of the principle of the present invention.

Fig. 2 is a schematic diagram of a device for extracting the relative velocity of a low-frequency electromagnetic vibrating table driven by a differential output power amplifier.

3 is a schematic diagram of a device for extracting the relative velocity of a low-frequency electromagnetic vibrating table driven by a single-ended output power amplifier.

Detailed ways

Example 1

This embodiment takes a low-frequency electromagnetic vibrating table driven by a differential output power amplifier as an example to specifically describe the device for extracting the relative motion of the low-frequency electromagnetic vibrating table, as shown in FIG. 1 and FIG. 2 .

The device for extracting the relative motion of the low-frequency electromagnetic vibrating table driven by the differential output power amplifier includes pure resistance, the first subtractor J1 and the first proportional amplifier F1;

The pure resistance is connected in series with the driving coil of the vibrating table, one end of the pure resistance is connected to one end of the driving coil, the other end of the pure resistance is connected to the output end of the differential output power amplifier, and the other end of the driving coil is connected to the other end of the differential output power amplifier. an output connection;

The common end u _A of the differential output power amplifier and the drive coil is connected to the minuend input end of the second subtractor J2, and the common end u _C of the differential output power amplifier and the pure resistance is connected to the subtrahend input end of the second subtractor J2 The output signal of the second subtractor J2 is used as the total voltage drop of the pure resistance and the driving coil, and the output terminal of the second subtractor J2 is connected with the minuend input terminal of the first subtractor J1, that is, the pure resistance and the drive coil The total voltage drop of the coil is input into the first subtractor J1 as the minuend;

The differential output power amplifier and the common end u _C of the pure resistance are connected to the subtrahend input end of the third subtractor J3, the driving coil and the common end u _B of the pure resistance are connected to the minuend input end of the third subtractor J3, The output value of the third subtractor J3 is used as the voltage drop at both ends of the pure resistance, and the output terminal of the third subtractor J3 is connected with the input terminal of the first proportional amplifier F1, that is, the voltage drop at both ends of the pure resistance is input to the first ratio Amplifier F1;

The first proportional amplifier F1 outputs the amplified pure resistance voltage drop, and the amplified pure resistance voltage drop is input in the first subtractor J1 as a subtrahend; the output signal of the first subtractor J1 represents the relative motion of the vibrating table speed;

The magnification of the first proportional amplifier F1 Among them, R is the equivalent DC resistance of the driving coil of the vibrating table, and _R1 is the resistance value of pure resistance.

The total voltage drop between the pure resistance and the driving coil is u ₁ =(R+R ₁ )i+Li'+Blx', where L is the equivalent inductance of the driving coil of the vibrating table, B is the magnetic induction of the air gap magnetic field, and l is The winding length of the driving coil, i is the current input to the driving coil of the vibrating table, i' is the derivative of i to time, x is the displacement of the driving coil of the vibrating table relative to the installation base of the vibrating table, x' is the derivative of x to time, is the relative velocity of the vibrating table.

The voltage drop across the pure resistance is u ₂ =R ₁ i; therefore, the output signal of the first subtractor J1 is Δu=u ₁ -K ₁ u ₂ =[R+(1-K ₁ )R ₁ ]i+Li'+Blx'=Li'+Blx'; from the driving equation mx″+cx'+kx=Bil of the low-frequency electromagnetic vibrating table, the frequency characteristic equation of the system can be obtained as Then the amplitude ratio of displacement x and driving current i can be obtained The amplitude ratio of Li' and Blx' can be expressed as $\left|\frac{L\·\mathrm{j\ω}\&Center\; Dot;I\left(\mathrm{j\ω}\right)}{\mathrm{Bl}\·\mathrm{j\ω}\·x\left(\mathrm{j\ω}\right)}\right|=\frac{L}{\mathrm{Bl}}\left|\frac{I\left(\mathrm{j\ω}\right)}{x\left(\mathrm{j\ω}\right)}\right|=L\sqrt{\frac{{(k-{\mathrm{m\ω}}^2)}^2+{\left(\mathrm{c\ω}\right)}^2}{{\left(\mathrm{Bl}\right)}^2}}.$ According to the actual system parameters, under low frequency conditions, and (Bl) ² have the same order of magnitude, and L is of the order of 10 ^-3 Heng, so it can be considered that the amplitude of Li' is much smaller than that of Blx', and it can be obtained that Δu≈Blx'. In the above expression, m is the mass of the moving parts of the electromagnetic vibrating table, c and k are the damping and stiffness of the elastic supporting parts of the electromagnetic vibrating table, x" is the twice derivative of x to time, which is the relative acceleration of the vibrating table, C( jω) and I(jω) are the Fourier transforms of x and i respectively, ω is the angular frequency of vibration.

Through the technical means of optimizing the shape of the air gap, the magnetic induction intensity B of the air gap can be kept constant in the entire range of the vibration table, that is, the voltage difference signal Δu obtained by Δu=Blx' is proportional to the relative speed x' of the vibration table, The voltage difference signal Δu can characterize the relative velocity x' of the vibrating table.

The first subtractor J1 is respectively connected with the integrator or the differentiator or the second proportional amplifier F2, the output signal of the integrator represents the relative displacement of the shaking table, the output signal of the differentiator represents the relative acceleration of the shaking table, and the output signal of the second proportional amplifier F2 The output signal is the amplified relative velocity of the shaking table.

Since the resistance of the drive coil is not easy to measure accurately, _K1 is difficult to obtain accurately through calculation and can only be determined through gradual adjustment. Further limit: the adjustment method of the magnification _K of the first proportional amplifier F1 comprises the following steps:

(1) The driving coil of the vibrating table is connected in series with a pure resistor and then fed with a constant current I;

(2) Obtain the output signal Δu of the first subtractor J1,

Δu=u ₁ -K ₁ u ₂ =[R+(1-K ₁ )R ₁ ]I+LI'+Blx',

Wherein, I' is the derivative of I to time;

(3) Wait for the vibrating table to be stationary, at this time the relative speed of the vibrating table x'=0, so Blx'=0; at the same time, because the current I passed is a constant current, that is, I'=0, so LI'=0 , so that Δu=u ₁ -K ₁ u ₂ =[R+(1-K ₁ )R ₁ ]I can be calculated;

(4) Adjust K ₁ until Δu=0, at this time The adjustment is complete.

The adjustment of the magnification _K1 is carried out before the extraction test of the relative motion amount. For the specified vibration table and pure resistance, once the adjustment of _K1 is completed, it cannot be changed again.

In order to improve the adjustment accuracy of _K1 , it is further limited: when adjusting the amplification factor of the first proportional amplifier F1, the output signal of the second proportional amplifier F2 is used as a reference signal, and the amplification factor of the second proportional amplifier F2 is _K2 ( _K2 >1 ), in step (4), adjust K ₁ until K ₂ Δu=0. Since the value of K ₂ Δu is obviously greater than Δu, it is easy to monitor and can improve the adjustment accuracy of K ₁ .

The electromagnetic vibrating table is a typical electromechanical coupling system, and the mechanical movement must be reflected in the electrical link. Firstly, current is passed into the coil, and under the action of electromagnetic induction, an ampere force is generated to drive the vibrating table to move. During this process, the driving coil of the vibrating table cuts the magnetic induction line, and an induction reflecting the relative velocity of the vibrating table is generated in the coil electromotive force. By extracting the coil voltage signal, and considering that when the electromagnetic vibrating table operates under low frequency conditions, irrelevant components can be ignored or removed by a certain method, the voltage signal reflecting the relative velocity of the vibrating table can be obtained, and at the same time, the existence of The differential and integral relations of the model, other momentum can also be easily obtained; through further processing of the obtained motion, it can be used for feedback control of the low-frequency vibration table.

Example 2

This implementation takes a low-frequency electromagnetic vibrating table driven by a single-ended output power amplifier as an example to specifically illustrate the extraction device for the relative motion of the low-frequency electromagnetic vibrating table, as shown in Figures 1 and 3.

The device for extracting the relative motion of the low-frequency electromagnetic vibrating table driven by a single-ended output power amplifier, including pure resistance, the first subtractor J1 and the first proportional amplifier F1;

The pure resistance is connected in series with the driving coil of the vibrating table, the output end of the single-ended output power amplifier is connected with the driving coil, one end of the pure resistance is grounded, the common end u _A of the single-ended output power amplifier and the driving coil is connected to the passive terminal of the first subtractor J1 The subtrahend input terminal is connected, and the voltage drop of the single-ended output power amplifier and the common terminal u _A of the driving coil is used as the total voltage drop of the driving coil and pure resistance of the vibrating table, that is, the total voltage drop of the pure resistance and the driving coil is used as the minuend input In the first subtractor J1;

The voltage drop between the driving coil and the common terminal u _B of the pure resistance is regarded as the voltage drop across the pure resistance, and the common terminal u _B of the driving coil and the pure resistance is connected to the input terminal of the first proportional amplifier F1, that is, the voltage drop input at both ends of the pure resistance In the first proportional amplifier F1;

The first proportional amplifier F1 outputs the amplified pure resistance voltage drop, and the amplified pure resistance voltage drop is input in the first subtractor J1 as a subtrahend; the output signal of the first subtractor J1 represents the relative motion of the vibrating table speed;

The magnification of the first proportional amplifier F1 Among them, R is the equivalent DC resistance of the driving coil of the vibrating table, and _R1 is the resistance value of pure resistance.

The first subtractor J1 is respectively connected with the integrator or the differentiator or the second proportional amplifier F2, the output signal of the integrator represents the relative displacement of the shaking table, the output signal of the differentiator represents the relative acceleration of the shaking table, and the output signal of the second proportional amplifier F2 The output signal is the amplified relative velocity of the shaking table.

In this embodiment, the adjustment method of the amplification factor _K1 of the first proportional amplifier F1 is the same as that in Embodiment 1.

The content described in the embodiments of this specification is only an enumeration of the implementation forms of the inventive concept. The protection scope of the present invention should not be regarded as limited to the specific forms stated in the embodiments. Equivalent technical means that a person can think of based on the concept of the present invention.

Claims (4)

1. Extraction element of low frequency electromagnetic vibration platform relative motion volume, its characterized in that: the circuit comprises a pure resistor, a first subtracter and a first proportional amplifier;

the pure resistor is connected with the driving coil of the vibration table in series, and the total pressure drop of the pure resistor and the driving coilThe input is the first subtracter as the number to be subtracted;

voltage drop across a pure resistorThe first proportional amplifier outputs amplified pure resistance voltage drop, and the amplified pure resistance voltage drop is input into the first subtracter as a subtraction number; the output signal of the first subtracter represents the relative motion speed of the low-frequency vibration table;

amplification factor of first proportional amplifierWhereinRIs the equivalent dc resistance of the drive coil of the vibration table,R ₁is the resistance of a pure resistor.

2. The device for extracting the relative movement amount of the low-frequency electromagnetic vibration table as claimed in claim 1, wherein: the first subtracter is respectively connected with the integrator, the differentiator and the second proportional amplifier, the output signal of the integrator represents the relative displacement of the vibrating table, the output signal of the differentiator represents the relative acceleration of the vibrating table, and the output signal of the second proportional amplifier is the amplified relative speed of the vibrating table.

3. The device for extracting the relative movement amount of the low frequency electromagnetic vibration table as claimed in claim 2, wherein: amplification factor of first proportional amplifierK ₁The adjusting method comprises the following steps:

(1) the drive coil of the vibration table is connected with a pure resistor in series and then is introduced with direct currentI；

(2) Obtaining the output signal of the first subtracter，

；

Wherein,Lis the equivalent inductance of the drive coil of the vibration table,Bis the magnetic induction intensity of the air-gap magnetic field,lin order to drive the coil winding length,xfor displacement of the vibration table drive coil relative to the vibration table mounting base,is thatxThe derivative with respect to time, i.e. the relative speed of the oscillating table,is composed ofIA derivative with respect to time;

(3) waiting for the vibration table to stabilize to obtain；

(4) And adjustingK ₁Up toAt this timeAnd finishing the adjustment.

4. The apparatus for extracting the relative movement amount of the low frequency electromagnetic vibration table as claimed in claim 3, wherein: when the amplification factor of the first proportional amplifier is adjusted, the amplification factor is improvedK ₁The output signal of the second proportional amplifier is used as a reference signal, and the amplification factor of the second proportional amplifier isK ₂WhereinK ₂>1, adjustingK ₁Up to。