SU1642258A1 - Method for determination of natural oscillations of a balance with magnetoelectric balancing - Google Patents

Abstract

The invention relates to a weight measuring instrument and is intended for use in the attestation of the dynamic characteristics of scales with power compensation on the basis of magnetoelectric converters. The aim of the invention is to improve the accuracy of determining the values of the degree of attenuation and the natural frequency of the movable part of the scale. When the moving part of the balance is excited, a current is applied to the coil of the magnetoelectric converter until the transients in the mechanical part of the balance are completely attenuated, then the current supply is stopped and a signal proportional to the square of the output signal of the coil of the magnetoelectric converter is generated, and the square signal of the signal is integrated before the full damping transient processes in the mechanical part of the balance, register the intermediate result of integrating the square of the first half wave of the coil signal and calculate the attenuation degree and natural frequency of the moving part. 2 Il. SO with

Description

The invention relates to high-measurement instrumentation and is intended for use in the attestation of dynamic characteristics with strong compensation on the basis of magnetoelectric converters.

The purpose of the invention is to improve the accuracy and enhance the functionality by determining the degree of attenuation of the natural frequency of the moving part of the balance.

Fig. 1 shows a block diagram of an apparatus for carrying out the method; figure 2 is a diagram of the equivalent transformation of the IEP.

The device includes a moving part 1 (IF) of the balance, a coil 2 and a magnet 3 of a magnetoelectric converter (MEP), an elastic element 4 of the IF suspension, a balance balancing node 5, a switch 6, a DC generator 7, a multiplication circuit 8 (quad), similar integrators 9 and 10, analog-to-digital converters 11 and 12, comparator 13, computing device 14, control unit 15.

In addition, the device contains a coil 16 MEP, resistance 17, equivalent resistance 18 losses, causing the attenuation of the inverter 1, the key 19.

The theoretical content of the proposed invention is based on the idea of the degree of attenuation as an indicator of the dissipation of energy stored in the balance mechanism when a current pulse is applied to the IEP coil. In this case, the power dissipated by sv -f ttbt

the substitute with the speed of the inverter 1, with the value of which is associated with the value of the voltage at the output of the coil 2U (t), induced in the coil 2 as it moves in a magnetic field in the gap of the MEP magnetic system 3, recorded

) bt

U (t) U0e

(1) where Uo is the signal amplitude;

(Oo is the circular frequency of natural oscillations of IF 1, Sho 2n f0.

A signal proportional to the signal energy U (t) is described by

° -uuo f4.

h..1 -. ()

(2)

Analysis of expression (2) shows that the value of / Can be determined by registering the values of the integral of the square of the signal during the first half-wave of the signal and the final result of the integrated 3Z

nor X1 0, t2 - for the first

(OO V1 -F

half waves, ti 0 and tz oo for the final result)

Zheg + 1G (3

0 (

where PI, Pk are the results of integration of the first half-wave and the final one, respectively.

When registering the integral of the square of the signal at the end of the first half-wave Pi and at the end of the second half-wave P2, the value of ft is calculated

2 ПЧ2. . , - |

/ (

In

P2-P1

P1

 +

(four)

By making an equivalent replacement of the dampers in the weights with the damping quality created by the resistor 18 (FIG. 2), it is possible to record

0

TO

(five)

2ftJbm Rie where K is the conversion coefficient of the MEP;

m is the total mass involved in the oscillatory process (for the case of direct mode IF 1).

When current is supplied to the coil 2, the inverter 1 is shifted by an amount (switch 19 is open)

K X (6)

x

W

where W is the stiffness of coil suspension springs 2.

Potential energy stored in this spring

Qn W.

(7)

Energy dissipated is determined by the ratio (key 19 is closed)

(t) l3 (t) dt (t) f dt.

see about

(eight)

where t is the integration time until the transition process in the mechanical system of scales is completely attenuated.

To exclude K, I, m, W from consideration, considering that U (t) Ki is written

15

x Ј / and (t) dt,

(9)

and taking into account that ui W / m taking into account (6, 7, 8) we transform (5) to the form

tK

(t) 2dt

fo tK

 2rP

(g); p

P A.

(ten)

The selection of the half-waves of the analyzed signal U (t) is performed by the comparator 13,

squaring the analog signal - an analog signal multiplier (quad) 8. At the time of stopping the supply of current to coil 2, control unit 15 zeroes integrator 9 and 10. E calculator 14 calculates the value / from (3) and then fo by (y).

The device operation algorithm is as follows: turn on the switch 6;

exposure time interval to decay transients; switch off switch b with simultaneous resetting of integrators 9 and 10; integrating coil 2 output to full

damping oscillations and integrating the square of the signal until the end of the first half-wave and until the oscillations are completely damped; calculation of attenuation values / and natural frequency f0 of the moving part of the scale.

Claims (1)

The invention The method of determining the frequency of natural oscillations of scales with magnetoelectric balancing, consisting in excitation of the movable part by supplying current to the coil of the magnetoelectric converter with subsequent analysis of the process of its movement, characterized in that, in order to increase accuracy and enhance functionality by determining the degree of attenuation, the current is supplied to the coil of the magnetoelectric converter to complete attenuation of transient processes the mechanical part of the balance, and the analysis of the process of moving the movable part of the balance is carried out by the output voltage of the coil of the magnetoelectric the forming, the formed signal proportional to the square of the voltage, the integration is performed and the output voltage signal generated before a complete decay of the balance oscillation movable latching integration result signal in the moment of termination of the first half-wave and calculate the frequency f0 of natural oscillations and the degree of attenuation / by the formulas / 5 () 2 + lH In Pk - Pi P7 f -Mp TOL- - l: A to where PI is the result of integrating the voltage square during the first half wave; RK is the final result of integrating the voltage square; Ak is the final result of voltage integration. I / ft)