SU1689869A1 - Device for measuring phase shift of harmonic signals - Google Patents

Abstract

The invention relates to a measurement technique and can be used to measure the phase shift of two harmonic signals having a constant component. The aim of the invention is to simplify the device. The device implementing the method contains the first and second drivers 1 and 2, the generator 3, the two-input logic circuit OR 4, the three-input logic circuit AND 5, the two-input logic circuit AND 6, counter 7, inputs 8 and 9. The feature of the device is The introduction of the schemes OR 4 and AND 6, which allows to simplify the device. 3 il.

Description

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The invention relates to the field of measurement technology and can be used in digital phase meters.

The purpose of the invention is to simplify the device.

Figure 1 shows the structural electrical circuit of the device for measuring the phase shift of harmonic signals; Fig. 2 shows voltage plots explaining the essence of the method for determining the phase shift of harmonic signals; Fig. 3 shows voltage plots explaining the operation of a device for measuring the phase shift of harmonic signals.

The device contains the first driver 1, the second driver 2, the generator 3, the circuit OR 4, the first and second circuits AND 5 and 6, the counter 7. The inputs of the drivers 1 and 2 are the inputs 8 and 9 of the device. The output of the imaging unit 1 is connected to the first input of the OR circuit 4 and the second input of the AND 5 circuit, the third input of which is connected to the second output of the generator 3, and the first input of the AND 5 circuit is connected to the output of the imaging unit 2 and the second input of the OR circuit 4 whose output is connected to the first input circuit AND 6, the second input of which is connected to the first input of generator 3, and the output of circuit AND 6 is connected to the first summing input of counter 7, the second subtractive input of which is connected to the output of circuit AND 5, while the control input of counter 7 is the input Reset devices.

The device works as follows.

The first signal Ui (t), having a constant component Ci, is compared with the first given constant voltage Ui, and the second signal U2 (t), having a constant component C2. - with a second predetermined constant voltage 112 (Fig. 2). At the time ti of the first comparison of the signal Ui (t) with a constant voltage Ui, the beginning of the first time interval n is fixed, the end of which is fixed at the time m.4 of the second comparison of the signal U2 (t) with a constant voltage (J2. At the time t2 of the first comparing the signal L) 2 (t) with a constant voltage U2, the second time interval ha begins. The countdown of the duration of this time interval T2 ends at the moment t.3 of the second comparison of the signal Ui (t) with a given constant voltage UL

The phase shift between the signals Ui (t) and U2 (t) is determined from the relation

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. A device for measuring the phase shift of harmonic signals operates as follows.

Shaper 1 forms the output

voltage pulse Ui (fig.Z), the duration of which is equal to the time during which the amplitude of the signal Ui (t) exceeds the value of the first constant voltage Uonb set in shaper 1

0 Shaper 2 generates a voltage pulse U2 at the output (FIG. 3). the duration of which is equal to the time during which the amplitude of the signal U2 (t) exceeds the value of the second set in shaper 2

5 constant voltage U0n2.

At the output of the logic circuit OR 4, a voltage pulse UA is formed, the beginning of which corresponds to the instant of the first intersection of the constant voltage U0ni by the signal Ui (t), and the rear edge of this pulse corresponds to the instant of the second crossing of the constant voltage U0n2 by the signal U2 (t). This voltage pulse U4 is fed to one of the inputs of the circuit AND 6,

5 ne, the second input of which receives voltage pulses Uz from one of the outputs of generator 3, which generates paraphase pulse sequences at the outputs that do not overlap in time (the voltage of voltage Ua and from FIG. 3). As a consequence, a series of voltage pulses Ue is formed at the output of circuit AND 6, the number of pulses in which is proportional to the time interval between the moment

5 of the first crossing by the signal Ui (t) of the constant voltage U0ni and the moment of the second crossing by the signal U2 (t) of the constant voltage U0n2 (FIG. 3). The impulses of the voltages Ui and U2 from the outputs of the formers 1 and 2 also receive the circuits of the AND 5 circuit, to the third input of which voltage pulses come and from the other output of the generator 3. Therefore, a series of pulses of voltage Us (Fig. 3), the number of pulses 5 in which is proportional to the time interval between the moment of the first crossing by the signal Ua (t) of a constant voltage and the time of the second crossing by the signal of Ui (t) of a constant voltage

0 Uoni.

The pulses from the output of the circuit And 5 are fed to the summing input of the counter 7, and the pulses from the output of the circuit And 5 are fed to the subtractive input of the counter 7. Owing to

5 this counter 7 counts the number of pulses equal to the difference of the pulses contained in the series of pulses at the outputs of circuits 6 and 5. Since the number of pulses at the outputs of the indicated logical

the circuits are proportional to the time intervals ri and T2 (FIG. 2), then using the meter readings, one can judge the phase shift between the signals Ui (t) and U2 (t) at the inputs of the device. Before the start of the next measurement cycle on the input. The counter is reset, the counter returns to its initial zero state.

Thus, the invention, by providing a measurement of the phase shift between two harmonic signals, makes it possible to simplify the device and increase its reliability by reducing the number of constituent elements of the device while maintaining its necessary functionality.

Claims (1)

Apparatus of the Invention A device for measuring the phase shift of harmonic signals, comprising first and second drivers, each of which includes a comparator, and Uf (t) having a reference input for connecting a voltage source, the inputs of which are the inputs of the device, the counter whose output is the output of the device, the terminal that is connected to 5 control input of the counter, characterized in that, in order to simplify the device, the first and second AND circuits, the OR circuit, a generator, which has two outputs, are introduced, the outputs of the first and second drivers are connected to the first and second inputs, respectively, of the OR circuit, respectively and the first circuit AND, the output of the circuit OR through the second circuit AND, and the output of the first circuit AND directly 5 are connected respectively to the summing and input subtractive inputs of the counter, the first and second paraphase outputs of the generator are connected respectively to the second and third inputs, respectively 0 of the first and second circuits, And, and the terminal is used to connect the-signal reset. FIG. 2 and U, (t) about , “ 0хг.З