RU1777108C - Method of and device for determining parameters of electromechanical converter - Google Patents

Description

The invention relates to measuring technique, geophysics and can be used, in particular, to determine the parameters of electrodynamic or magnetoelectric seismic receivers of electrodynamic sound-emitting heads, microphones, etc.

The purpose of the invention is to increase the accuracy and noise immunity of determining the natural frequency of the conversion coefficient and the degree of attenuation of electromechanical converters, as well as determining the degree of asymmetry of the converters.

In FIG. 1 shows devices for determining the parameters of an electromechanical transducer; FIG. 2 shows a negative impedance element; in FIG. 3 - time diagrams of the device ..

In the measurement, the current pulse in the excitation is supplied to the circuit formed by the serial connection of the electromechanical converter under study and an element with an equivalent negative inductance equal to or close to the inductance of the converter coil. The duration of the excitation current pulse is selected sufficient so that the total amplitude of the voltage fluctuations at the terminals of the converter under study and the negative inductance element decreases to a level not exceeding the product of the amplitude of the first oscillation and the required error in determining the parameters

converter. At the end of the action of the excitation pulse, the voltage U (t) is integrated, which is equal to the algebraic sum of the voltage Ui (t) at the terminals of the converter under study and the voltage U2 (t) at the terminals of the negative inductance element, minus the voltage 1) s ( 0, present at the terminals of the additionally introduced compensation converter.

integrations are chosen to be equal to or close to the duration of the excitation pulse. In addition, two voltages proportional to the square and

voltage cube U (t). Using the values of the three voltages And, 2 and h at the outputs of the integrators, at the end of the integration cycle, the natural frequency a is calculated. power

attenuation and conversion coefficient K by the formulas

or- 1- (4)

g.

I- And

 g; P

s and 2 (a

)

1

(5)

/J-0.5J8 j2T / (l2) -2)

K ™ v7 / T rh / li, (6)

where T is the constant of integration of integrators;

M and 1B are the a priori known values of the inertial mass of the converter and the excitation current,

then a second pulse of an excitation current of equal duration but opposite polarity is applied; the values of the three integrals I, 2 and h are determined in a similar way. calculate the degree of asymmetry in the Converter according to the formula: I hi-

5 tttggttt (7)

To reduce the influence of the additive error of the integrators on the result of determining the parameters of the converter, the latter can be calculated by the formulas

w (AVR) 2 / TSix

S3 153 I + From I

ftj (AVR), / 3 (AVR) and K (AVR) - respectively, the averaged values of the natural frequency, the degree of attenuation and the conversion coefficient of the electromechanical converter,

The device contains a series 1 electromechanical converters under study 1 and 2, an excitation current source 2 connected through a switch 4 and a polarity switch 5 to a connection point between converters 1 and 2, element 6 with an equivalent negative impedance of an inductive nature, connected between a common bus and a free terminal the investigated converter, voltage multipliers 7 and 8, integrators 9-11 with reset to zero, analog-digital computing device 12 and control unit 13 connected accordingly, the negative impedance element 6 can be implemented according to the scheme (see Fig. 2) and comprise an operational amplifier (op-amp) 1. constant resistors 2-4. capacitor 5. Equivalent inductance I. series resistance R. The operation of the device according to the circuit of FIG. 1

illustrated by timing diagrams in FIG. 3.

The device operates as follows.

At the initial moment, the contacts of the switch 5 and the key 4 are in the position shown in FIG. 1. By the signal I of the control unit (BU) 13, the source 3 of the excitation current is connected to the converter 1 under investigation: by the signal III

integrators 9-11 are reset. At the end of the action of the excitation pulse, the integration cycle of the signals U (t), V (t) and Q (t) begins. At the end of the integration cycle BU 13 generates a signal IV

start analog-digital computing device (WU) 12, which performs the calculation of the parameters w, / and K according to formulas (4) - (6).

If necessary, BU 13 forms

the drive current polarity switching signal I and all operations are repeated as previously described. After the second integration cycle is completed, the averaged parameters vj (AVR) are calculated.

Claims (2)

/ 3 (AVR) and K (AVR) and degree S of asymmetry of transducer 1 according to formulas (7) - (10). SUMMARY OF THE INVENTION 1. Method for determining the parameters of an electro-mechanical converter. the method consisting in excitation of a converter loaded with a negative resistance and analysis of a transient process of damped oscillations from voltage signals, characterized in that that, in order to increase the accuracy of determining the parameters of the converter, when analyzing the transient process at the end of the excitation pulse, the voltage Ui (t) on the studied voltage converter U2 (t) at the negative resistance and the voltage Daft), equal to the noise of the signal component Ui (t), with the opposite sign, from the sum of the voltage U (t) obtained, the voltages V (t) and Q (t) are formed, which are proportional to the square and the cube of voltage U (t), integrate voltages U (t), V (t) and Q (t) during time T, then excite second electric converter. tric pulses of duration and magnitude, but of opposite polarity, and carry out similar summation and integration of the voltage, and the natural frequency W of the oscillations, the degree of / J attenuation and the conversion coefficient K is determined by the formulas: with Mi I- I li l. 5 ThT + TTjT W 1 / r-liVr4 Ii / l3-3 (li / l2) 2: / 0.5-V8. | 22 / (3 -11 13) K WVM .Tli / lb 1 t i / U (t) dt: I2 - 7 / V (t) dt; I3 about where and 1 t / Q (t) dt are the values of the integrals, e.g. ratios U (t), V (t), Q (t) obtained upon excitation of the converter by the first pulse; And is the voltage integral U (t) obtained upon excitation by the second pulse; g is the time constant of integration; M and B are the a priori known values of the inertial mass of the converter and the excitation current. 2. A device for determining the parameters of an electromechanical transducer, containing an excitation current source and a negative resistance element, the first output of which is adjacent is connected to the device’s common bus, and the second output is a terminal for connecting the first output of the studied transducer, a controlled key and an analog-to-digital converter, the output of which is connected to the control unit, characterized in that, in order to increase the measurement accuracy and increase the number of measurements simultaneously parameters of the converter, three integrators, two voltage multipliers, a current polarity switch and a compensating electromechanical converter located on the base designated for installation of the studied converter, the first output of the compensation converter being a terminal for connecting the second output of the studied converter, the second output of the compensation converter is connected to both inputs of the first multiplier, the first input of the second multiplier, the input of the second integrator and the second input of the second multiplier, the output of which is connected with the input of the third integrator, the outputs of all integrators are connected to the inputs of the analog-to-digital converter. 1 fi2. 2 Editor T. Shagova Compiled by A. Kashaev Tehred M. Morgenthal . 3. Proofreader O. Gusti