SU817605A1 - Digital phase meter - Google Patents

Description

one

The invention relates to digital measurement technology and can be used to determine the phase characteristics of quadrupoles in automatic control and regulation systems, including at infra-low frequencies.

Nowadays, digital phase meters are widely used to measure the phase angle.

The principle of construction of digital phase meters in the range of infra-low frequencies is based on measuring the time intervals between the same points of transition of the studied signals through the zero level. At the same time, the measurement time of the phase shift varies depending on the period of the studied signals.

If during the time between the two zero-crossing zero-crossing instantaneous values of the studied signals, N is calculated, then the measured phase shift is

-I

c

W is the circular frequency;

Where

f is the frequency of the counting pulses,

In the study of real automatic control systems at infrared frequencies, the appearance of a constant component in the output signal is possible, due to the peculiarity of circuit design and the specifics of their operation. The constant component introduces an error in the measurement of the phase shift, which depends on the magnitude of the constant component with respect to the amplitude of the measured signal. To improve the accuracy of the measurement of the phase shift, it is necessary to measure and take this error into account.

five

A digital phase meter is known, which allows measuring the phase shift in the infra-low frequency range taking into account the error introduced by the presence of a constant component containing a pulse generator, a recorder of the maximum of the voltages under study, a reference frequency generator, a frequency multiplier, electronic, key, recording device 1

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Also known is an infra-low frequency phasemeter-generator, containing null-organs, determining the moments of the transition of measured signals through zero, inverters, switches, OR circuits, 0 control triggers, reversible

counter, infra-low frequency generator 2.

A disadvantage of the known devices is the complexity of the circuit, the presence of a large number of elements, which reduces the reliability of the device. In addition, in the known devices the measurement accuracy is insufficient. t

The purpose of the invention is to increase the reliability and accuracy of measurement.

The goal is achieved by the fact that a phase meter containing two zero-organs connected by their inputs to the first two inputs of the phase meter and outputs to the inputs of two NOT elements and to the first inputs of the two first elements AND, the second inputs of which are connected to the output of the third element AND connected to the third input of the phase meter by the first input, and the second to the trigger trigger output, which also contains two OR elements, the first of which is connected to the outputs of the first two AND elements and the output to the counter input and the trigger No, two triggers and four additional AND elements are entered, the first of which is connected to the outputs of the NOT elements with the third inputs of the first two AND elements, and the output with the control trigger input and the second input of the second additional element I, the first input of which is combined with the third input of the third element And and with the second inputs of the third and fourth additional elements And connected by the first inputs to the second input of the first element OR, and the third to the zero outputs of the triggers entered, single The outputs of which are connected via the second OR element to the third input of the second, additional element AND, and the single inputs to the outputs of the third and fourth additional elements AND, while the output of the second additional element AND is connected to the trigger trigger input, and the output of the phase meter is the output of the first entered triggers.

Figure 1 shows the functional scheme of the proposed device; 2 shows graphs explaining the operation of the device.

The digital phase meter contains inputs 1,2 and 3, zero-organs 4 and 5, trigger trigger b, elements NOT 7 and 8, elements AND 9-15, elements OR 16 and 17, control trigger 18, triggers 19 and 20, counter 21 and exit 22.

The device works as follows.

Before the start of measurement, the command Set Zero (AC) is given to the zero inputs of trigger trigger 6, control trigger 18, trigger 19 and

20 and counter 21. At the same time counter

21, and all the specified triggers are set to zero: at zero outputs (indicated by a dot), high potential, and at single outputs, low potential. All And elements work when high potential is present at all inputs. In the initial state, all the indicated elements And are closed and the counter 21 does not receive counting pulses, which are fed to the input 3.

Suppose that the input signal at input 1 is ahead of the signal at the input, at input 2. After the output of the V.O signal, the circuit is reset, and from the zero output of the trigger trigger b, a high potential enters the input of the element 9. At time (FIG. 2) high potentials from elements HE 7 and 8, element 12 are fed to the inputs of element 12. the trigger of control -18 is triggered and tilted to a single position, while the high potential from its single output goes to the inputs of elements And 13, 14 and 15. However, only the element And 9 is triggered, and the pulse of the account from its output goes to the inputs of elements And 10 and 11.

At the moment of time, high potentials are supplied to the inputs of the terminal 10, it opens and the counting pulses flow through the element OR 16 to the counter 21 and directly to the input of the element 14, which is already prepared to be activated by high potentials at the outputs of the trigger 18 and trigger 20. Pulses the bills from the output of the AND unit 14 are fed to a single input of the trigger 19, which is tilted to a single position.

The low potential from the zero output of the trigger 19 enters the input element AND 15 and closes it, and the high potential from the single output of the trigger 19 enters through the element OR 17 to the input element And 13, as well as directly to the output 22. The high potential at the output 22 indicates that the signal at input 1 is ahead in phase of the signal at input 2.

At time t t, high potentials are applied to the inputs of the element 11 and it opens and the counting pulses flow through the element OR 16 to the counter 21 and to the input of the element 1 which is in the closed state and does not transmit pulses to the inputs of the trigger 20.

Claims (2)

At the moment of time tj - t g, high potentials are supplied to the inputs of the And 12 element; This confirms the unit state of control trigger 18, as well as the signal from the output of the element 12 and enters the input of element 13. From the output, its signal goes to the single input of the trigger trigger 6, which is tilted to the single position. The low potential from its zero output enters the input of element 9 and closes it. At this, the measurement process ends. Repeated measurement is possible only after the output of the signal U.O. If the signal at input 2 is ahead in phase of the signal at input 1, the circuit works in the same way, however, at the same time, element 11 starts working and element 10 starts working, which leads to triggering of trigger 20 in the time of trigger 19. In this case, the presence of a low potential at the output 22 indicates that the signal at input 2 is ahead of the signal at input 1. The proposed digital phase meter also, like the well-known low-frequency frequency generator, allows measuring the phase shift of sinusoidal signals with regard to errors introduced on the presence of a constant component in the signal under study. However, the proposed device has fewer elements, a simpler structure, which makes it possible to increase the reliability of the device. In addition, the proposed device allows to determine the sign and phase shift module with greater accuracy. DETAILED DESCRIPTION OF THE INVENTION Digital phase meter comprising two zero-organs connected by its inputs to the first two inputs of the phase meter and outputs to the inputs of two NOT elements and to the first inputs of the two first And elements, the second inputs of which are connected to the output of the third I. element connected by the first input to the third input of the phase meter, and the second to the output of the start trigger, which also contains two OR elements, the first of which is connected to the outputs of the first two elements AND and the output to the input. control trigger, characterized in that, in order to increase the reliability and accuracy of measurement, two triggers and four additional AND elements are introduced into it, the first of which is connected to the outputs of the NOT elements with the third inputs of the first two elements, and an output with a control trigger input and a second input of the second additional element And, the first input of which is combined with the third input of the third element And, and with the second inputs of the third and fourth additional elements And connected by the first inputs to the second input of the first element OR, and the third to the zero outputs of the entered flip-flops, the unit outputs of which are connected via the second OR element to the third input of the second additional element AND, and the single inputs to the outputs of the third and fourth additional elements AND, the output of the second An additional element And is connected to the trigger trigger input, and the phase meter output is the output of the first trigger that has been entered. Sources of information taken into account in the examination 1. Authorship certificate of the USSR № z11214, cl. G01 R 25/00, 1970. 2. Authors' certificate of the USSR No. 422322, cl. G01 R 25/00, 1972. TT: W.O. P w.o L t t; fpuf.l Schwyk. 1 P P 0 rm m y.ff W. O t t - t