SU894664A2 - Voltage comparing device - Google Patents

Description

(54) DEVICE FOR COMPARING VOLTAGES

one

The invention relates to electrical measuring equipment, in particular, to the class of precision comparing devices used to measure the difference between the effective values of two alternating voltages according to the periodic comparison method, and can be used in constructing precision indicators of the voltage deviation from the set level.

According to the main author. St. Is 636584 a device for voltage comparison is known, comprising an automatic switch, a first amplifier, a measuring transducer, a low-pass filter, a control circuit connected to one of the switch inputs, the other two inputs of which are connected to the outputs of the sources of the compared signals, and the switch output through the first amplifier connected to the input of the measuring converter, the output of which is connected to the input of the first

the information sample and storage unit and the first input of the second information sample and storage unit, the outputs of which are connected to the inputs of the subtractive unit, the output of which is connected to the output of the device and to the input of the second amplifier, while the output of the second amplifier is connected via the third sample and storage unit. to the second input of the second block

10 of the sampling and storage of information, and the second output of the second block of sampling and storage of information is connected through a third amplifier and a low-pass filter to the control input of the first

15 amplifier, and with control inputs. The first, second and third blocks of sampling and information storage are connected to the second, third, fourth outputs of the control unit II.

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A disadvantage of the known device is the low accuracy of voltage comparison due to the effect of additive error from an epithelial converter. The purpose of the invention is to improve the accuracy of voltage comparison. This goal is achieved by the fact that the separation unit of the maximum and minimum voltage values is added to the known device, the additional subtraction unit and the voltage divider whose output is the output of the device, and the input through the additional subtraction unit is connected to the outputs of the maximum and minimum selection blocks for example, the informational inputs of which are connected to the output of the main reading unit, and the control inputs, respectively, to the second and third outputs of the control unit, To the League. A diagram of a device for comparison of stresses is presented, and FIGS. 2 and 3 are diagrams illustrating the principle of comparing two deadly stresses in the presence of additive error — slow relative to the switching period of the drift. The device (Fig. 1) contains an automatic switch 1, an amplifier 2, which through a filter 3 nshknyh clock is connected to the control input of the amplifier 4, the output of which is connected to the input of the measuring transducer 5, the second low-pass filter 6, blocks 7 and 8 data sampling and storage, the outputs of which are connected to the inputs of the subtraction unit 9, the amplifier 10, the information sampling and storage unit 1, the control unit 2, the maximum and minimum value extraction units 13 and 14, the additional subtraction unit 15 and a divider 16 eg wives The system works as follows. The commuting rectangular voltage (Fig. Za) is supplied from control unit 12 to an automatic switching control input 1, which in turn connects the compared voltages UE and U (the amplification input of the bodies 4. At the output of the amplifier 4, an amplitude-modulated voltage is formed , the amplitude of the envelope of which carries information about the difference of the values of the compared signals U and U | (cL, in Fig. 24; The measuring transducer 5 extracts the envelope of the amplitude-modulated voltage, and after filtering the second harmonic 644 NICKY in the filter 6 lower hours The signal is fed to the inputs of blocks 7 and 8 for sampling and storing information.To write to blocks 7 and 8 of the measuring information (Fig. 2e) after the end of the transients on the low-pass filter 6, the control unit 2 forms two strobe-pulse sequences (Fig. 25 , &), with each pulse in the sequence being formed at the end of the corresponding half-period of the switching voltage (fit. 2c |). When strobe pulses affect blocks 7 and 8, the information in these blocks is updated, therefore, at intervals ofequal to T. Assuming there is no linear drift in the measuring transducer 5, the output voltages of blocks 7 and 8 would be constant voltages differing from each other by the amount of useful information sl (Fig. 2d, 3), but since the output voltage of a real electrothermal converter is the sum of useful information. With a repetition period of TC and a slow (with respect to T) linear Drift (Fig. 2e), the output signals of blocks 7 and 8 represent are stepwise voltages (Fig. 2e, x;). The plot (Fig. 2e), showing the output voltage of subtraction unit 9, shows that if there is additive error, the output voltage also contains a constant value of useful information with (variable component of the switching frequency, which is a parasitic signal, causing It is natural that the magnitude of the interference amplitude is directly proportional to the period of the switching voltage T - and proportional to tgd, where d is the angle of inclination of the direct linearly increasing voltage of the measuring transducer. In order to eliminate the interfering variable component, the output voltage of 1 block 9 (Fig. 2B and CSL) is fed to the inputs of blocks 13 and 14 for maximal and minimal voltage strobe operation, blocks 13 and 14 are synchronized with block strobe 7 and 8 with the help of strobe pulse sequences (Fig. 25, B 35, b). As follows from diagrams (Fig. 3g, e), block 14 stores and stores the voltage.

corresponding to the minimum level of the output voltage of block 9 of fig. 3v, block 13 stores and stores the voltage corresponding to the maximum voltage of block 9 (Fig. 33). After subtracting in the additional subtracting unit 15, and dividing it in half in the divider 16, only useful information remains at the output of the device, (Fig. Ze),

Thus, in the proposed device, by calculating the arithmetic average using the memory gating system, it is possible to significantly reduce the additive error of the measuring converter, while maintaining the required system speed. The use of such a device for the construction of differential voltage indicators allows the creation of accurate, highly sensitive devices for periodically comparing the effective values of alternating voltages with high speed.

Claims (1)

1. USSR author's certificate K 636584, cl. G 05 I / 01, 1976 (prototype). n n n n N n n n n ,, n n n n n " --J p np p p YOR. - n n n -t