SU1226321A1 - Method of converting alternating-to-constant voltage according to level of root-mean-square value - Google Patents

Abstract

The invention relates to electrical measurements and can be used in instruments for measuring effective values of a variable voltage of an infrared frequency. The purpose of the invention is to increase accuracy. This is achieved by generating the sum of orthogonal alternating voltages with pauses by performing cycles consisting of integration, inversion and reintegration, as well as changing the amplitude {1) of the indicated voltages by setting the initial integration conditions in pauses. A device for implementing the method comprises a block for forming time intervals 1, an amplitude detector 2, a converter 3, a sampling unit and a memory 4, a counting unit 5, integrators 6 and 8, controllable keys 7, 9, 11 and 12, an inverter 10. 1 or . S (L 1YO) with N9

Description

The invention relates to electrical measurements and can be used in instruments for measuring effective values of a variable voltage of an infra-low frequency.

The purpose of the invention is to improve the accuracy by generating a sum of orthogonal variable stresses with pauses by performing cycles consisting of integrating, inverting and reintegrating the amplitude of the indicated stresses by setting the initial conditions of integration into pauses.

The drawing shows a functional diagram of a device for converting a variable voltage of 5 kenai into a constant level of effective value.

The method of converting a variable voltage to a constant effective value level is that by performing cycles consisting of integration. inversion and reintegration, with pauses, the generated total of orthogonal voltages detected in amplitude, and the result of the detection will be remembered. During the pauses by the generation, the initial conditions of the integration operations are established, thus changing the amplitudes of the orthogonal voltages of one is proportional to the instantaneous amplitude of the input signal, and the other proportional to the memorized result of detection. The result of the detection is subjected to scale transformation and then memorized.

The method of converting alternating voltage into constant voltage can be implemented in a device that contains a block 1 for forming time intervals, an amplitude detector 2 with recording, a scale the converter 3, whose input is combined with an output of an amplitude detector 2, a block 4 of sampling and storage, an input which is connected to the output of the scale converter 3, and the output is connected to the output bus, trans; the counting unit 5, the input of which is connected to the first output of the time interval forming unit 1, and the output to the control input scale b Nogo second output transducer 3

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the block 1 of the formation of the time intervals is connected to the control input of the amplitude detector 2, and the third to the control input of the block

;; Sample and memorize. The input of the amplitude detector 2 is connected to the output of the first integrator 6, the input of which through the first control key 7 is connected to the output of the second

0 integrator 8, the input of the second integrator 8 through the second control key 9 is connected to the output of the inverter 10, the input of which is connected to the input a1хт of the Litudo detector 2, the input

15 setting the initial conditions of the second integrator 8 through the third control 1, the key 1 1 is connected to the input switch, and the input of the setting of the initial conditions of the first integrator is connected through the fourth controlled 1 switch 12 with the output of the amplitude detector 2. The fourth output of the block 1 forming the time intervals is connected to the control inputs of the first 7 and second 9 keys, and the fifth output - to the control inputs of the third 1 and fourth 12 keys, the recalculation unit 5 can be made of two binary counters.

30 A device for converting alternating voltage to a constant effective level works in the following manner,

35 The signal from block 1, the formation of time intervals, the amplitude detector 2 and the recalculated block 5 are zeroed. Then, according to the signal from block 1, the formation of time intervals

40 lock the third 1 and quarter 12 controlled keys. In this case, the integrators 6 and 8 are set to the stresses that determine the initial conditions for the integration. Voltage

45 integrator 6 is equal to zero (, nor so in: ak the output voltage of the amplitude detector is 2 U o, and the voltage on the integrator 8 is equal to the instantaneous value of the input voltage

30 Ug Ug ,, (t.), According to the signal from the block 1 of the formation of time intervals, the keys 11 and 12 are opened, and the yyuchi 7 and 9 are closed. In this case, the integrators 6, 8 and the inverter 10 form a ge5; i harmonic oscillator with a frequency Ы and an amplitude determined by the voltages (, c and g and g c, specifying the initial conditions of the oscillations.

The voltage at the output of the first integrator 6 will be equal to:

 you6 П a °

and at the output of the amplitude detector, respectively:

ix2 Ue, (t, V

Through time

the time interval shaping unit 1 opens the switches 7 and 9, as a result of which the generation is terminated, and closes the switches 11 and 12, as a result of which the integrators 6 and 8 are supplied with voltages corresponding to the initial integration conditions at the moment of time to

(tol, aUg, (io).

As a result of the next generation cycle, the output of the first integrator 6 forms the sum of the orthogonal stresses

JBbix6 u ex to) co5cot + iu io + r).

fi the result of the detection of this voltage at the output of the amplitude detector 2 is a voltage

"Hg (, D1, AI vD1, G1,

Further, the process is repeated many times. In the pauses between the generation of x-ray stresses, the initial conditions of integrators 6 and 8 are set. At the end of the averaging interval T, the number of periods of conversion of the input voltage is T

lt p-l at the output of the amplitude- s /

detector voltage 2 is set to voltage

ul.).

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If the value o differs from -JrT, then using the scale converter 3, controlled by the scaler 5, the voltage 5 Uptji g is averaged 5, resulting in a voltage corresponding to the effective value of the input voltage at the output of the scale converter 3. The output voltage of the scaled converter 3 according to the signal from the block 1 for forming the time intervals of the backup screw is stored in the block 4 for sampling and memorization.

J5 Using the operation of setting the initial levels of integrators in the pauses of the generation of orthogonal alternating voltages with the help of two integrators and inverters increases

20, the linearity of the signal conversion resulting in improved accuracy.

Claims (1)

Claim Method 25 voltages to a constant rms value consisting in generating the sum of orthogonal alternating voltages, changing a fflity of one of them in accordance with the amplitude of the input signal, detecting the sum of orthogonal variable voltages, remembering the result of the detection, changing the amplitude of another orthogonal variable voltage in accordance with the memorized result of detection, large-scale conversion of the result of detection, its subsequent sampling and memorized and, in contrast to the fact that, in order to increase the accuracy, orthogonal voltage variables are generated with pauses by performing cycles consisting of integration, inversion and reintegration, and the amplitudes of the orthogonal voltage variables change by setting the initial integration conditions in the pauses of the generation of the specified 30 35 40 50 SRI.