RU205166U1 - AC / DC MEASURING CONVERTER - Google Patents

Abstract

The utility model relates to electrical measuring equipment, and can be used to measure alternating voltage by converting it into direct voltage in a wide frequency range. The converter contains a differentiator, a division unit, two amplitude detectors, an analog multiplier, two quadrators, an adder and a square root extraction unit, and the input of the measuring transducer is connected to the inputs of the first quadrator and a differentiator, the output of which is connected to the first input of the division unit, and the outputs of the first and second quadrators are connected, respectively, to the first and second inputs of the adder, the output of which is connected through the square-root extraction unit to the output of the measuring transducer, the first input of the analog multiplier is connected to the output of the division unit, and the input of the converter is connected to the input of the first amplitude detector, the output of which is connected to the second input of the analog multiplier, the output of which is connected to the input of the second quadrator, and the output of the differentiator through the second amplitude detector is connected to the second input of the division unit. The technical result of the claimed utility model is to increase the speed of the converter spruce. 2 ill.

Description

The utility model relates to electrical measuring equipment, and can be used to measure alternating voltage by converting it into direct voltage in a wide frequency range.

Known measuring converter of AC voltage to DC [Patent for PM No. 163230 RF, IPC G01R 19/22, publ. 07/10/2016], containing a phase shifter, the first and second quadrators, an adder and a square root extraction unit, and the input of the converter is connected to the inputs of the first quadrator and a phase shifter, the output of which is connected to the input of the second quadrator, and the outputs of the first and second quadrators are connected, respectively to the first and second inputs of the adder, the output of which is connected to the output of the converter through the square root extraction unit.

The disadvantage of this converter is that, along with high speed and accuracy, its scope is limited only by measuring the power frequency voltage, since the phase mixer provides a phase shift of 90 ° only at this frequency. At other frequencies, the converter does not perform its function, since its output voltage will have a significant variable component, comparable to a constant one.

The closest analogue to the proposed utility model is an AC-to-DC measuring converter [Patent for PM No. 168459 RF, IPC G01R 19/22, publ. 08/05/2016], containing a differentiator, a division unit, the first and second quadrators, an adder, a square root extractor, a comparator and a frequency-to-voltage converter, and the input of the measuring transducer is connected to the inputs of the differentiator, the first quadrator and a comparator, the output of which is connected to the input of the frequency-voltage converter, the output of which is connected to the second input of the division unit, the first input of which is connected to the output of the differentiator, the output of the division unit is connected to the input of the second quadrator, and the outputs of the first and second quadrators are connected, respectively, to the first and second inputs of the adder, the output of which is through the square root extraction unit is connected to the output of the measuring transducer.

This technical solution was chosen as a prototype.

The disadvantage of this converter is its low speed, especially in the low-frequency region, due to the use of a frequency-to-voltage converter in the device, in the circuit of which a low-pass filter is used at the output. In this case, the time constant of the low-pass filter is selected sufficiently large based on the provision of the specified pulsations of the output control voltage at the lowest frequency of the operating range, which predetermines the low speed of the device in the entire operating frequency range.

The technical result of the claimed utility model is to increase the speed of the converter.

The specified technical result is achieved by the fact that the known AC-to-DC measuring converter containing a differentiator, a dividing unit, the first and second quadrators, an adder and a square root extraction unit, and the input of the measuring transducer is connected to the inputs of the first quadrator and a differentiator, the output of which is connected to the first input of the division unit, and the outputs of the first and second quadrators are connected, respectively, to the first and second inputs of the adder, the output of which through the square root extraction unit is connected to the output of the measuring transducer, the first and second amplitude detectors and an analog multiplier are additionally introduced, the first input of which is connected to the output division unit, and the input of the converter is connected to the input of the first amplitude detector, the output of which is connected to the second input of the analog multiplier, the output of which is connected to the input of the second quadrator, and the output of the differentiator through the second amplitude The th detector is connected to the second input of the division unit.

Significant differences of the proposed converter are the introduction of the first and second amplitude detectors and an analog multiplier, as well as a new organization of connections between the elements of the device. The combination of elements and connections between them ensure the achievement of a positive effect - increasing the speed of the converter.

The essence of the utility model is illustrated by drawings.

FIG. 1 shows a functional diagram of the device; in fig. 2 - timing diagrams of voltages u _in , u ₁ -u ₅ and u _out .

The converter (Fig. 1) contains a differentiator 1, a division unit 2, two amplitude detectors 3 and 4, an analog multiplier 5, two quadrators 6 and 7, an adder 8 and a square root extraction unit 9.

The converter works as follows. The input sinusoidal AC voltage u _in = U _{m in} sinωt is fed to the inputs of the differentiator 1 and the amplitude detector 3.

At the output of the differentiator 1, a voltage u _{1 is formed} , which is phase-shifted relative to u _in by an angle of 90 ° towards the lead, the amplitude of which is proportional to the frequency ω of the input signal u _in (Fig. 2):

where U _{m in} - the amplitude of the input voltage;

U _1m - the amplitude of the output voltage of the differentiator;

ω is the circular frequency of the input voltage;

R is the resistance of the differentiator resistor;

C is the capacitance of the differentiator capacitor.

After dividing the output voltage of the differentiator by its amplitude U _1m , formed by the amplitude detector 4, in the division unit 2, a voltage u ₂ = cosωt with a unit amplitude is formed at its output, which is fed to the first input of the analog multiplier 5.

In the analog multiplier 5, the voltage u _{2 is} multiplied with the amplitude value of the input voltage U _{m in} , coming from the amplitude detector 4, as a result, a voltage u _out = U _{m in} cosωt is formed at its output, thereby restoring the amplitude of the input voltage U _{m in} .

The _{voltages u in} = U _{m in} sinωt and u ₃ = U _{m in} cosωt are fed to the inputs of quadrants 6 and 7, respectively.

At the outputs of the quadrants 6 and 7, antiphase voltages u ₄ and u _{5 are formed} , obtained after squaring the voltages u _in and u ₃ , which pulsate with a double frequency of the input signal 2ω and have a constant component:

After summing up the voltages u ₄ and u ₅ in the adder 8 and transformations, at its output we have a voltage u ₆ that does not contain the variable component:

After the operation of extracting the square root in the block for extracting the square root 9 at its output and at the output of the device, a voltage u _out is generated.

The output constant voltage u _{out of the} device does not contain an variable component, and its value is equal to the amplitude of the measured input voltage U _{m in} , that is, in proportion to the effective value of U _in .

Thus, the elimination of the frequency-voltage converter from the device made it possible to get rid of the low-pass filter at its output, thereby achieving the technical result - an increase in the speed of the converter.

In the practical implementation of the proposed device, the differentiator 1 can be made according to the well-known scheme on an operational amplifier (OA) with a timing RC circuit. Division 2 can be performed on an op-amp by including a voltage multiplier on the KR525PS3 microcircuit in its negative feedback circuit. In this case, the input x of the multiplier must be connected to the output of the op-amp, the output through the resistor - to the inverting input, and the input y to apply voltage U _1m from the output of the amplitude detector 4. Amplitude detectors 3 and 4 can be made according to one of the known schemes (A.J. Peyton, W. Wolsh. Analog electronics on operational amplifiers. - M .: BINOM, 1994, p. 292, fig. 11.17; p. 304, fig. 11.29). Analog multiplier 5 can be performed on the KR525PS3 microcircuit. When building quadrators 6 and 7, you can use voltage multipliers on the KR525PS3 microcircuit, combining the x and y inputs. The adder 8 is a common op-amp adder. As a block for extracting the square root of 9, you can use an op-amp circuit by including a quadrator in its negative feedback circuit.

Claims (1)

An AC-to-DC measuring converter containing a differentiator, a dividing unit, the first and second quadrators, an adder and a square root extraction unit, and the input of the measuring transducer is connected to the inputs of the first quadrator and a differentiator, the output of which is connected to the first input of the dividing unit, and the outputs of the first and the second quadrators are connected, respectively, to the first and second inputs of the adder, the output of which is connected through the square-root extraction unit to the output of the measuring transducer, characterized in that the first and second amplitude detectors and an analog multiplier are additionally introduced into it, the first input of which is connected to the output of the division unit, moreover, the input of the converter is connected to the input of the first amplitude detector, the output of which is connected to the second input of the analog multiplier, the output of which is connected to the input of the second quadrator, and the output of the differentiator through the second amplitude detector is connected to the second input division block.

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