SU1337791A1 - Digital voltmeter - Google Patents

Abstract

The invention can be used. control systems of industrial processes and simplifies the conductivity of the voltmeter. The voltmeter contains a block of 1 input amplifiers. A / D converter .2, period determining unit 3, frequency driver 4, control unit 5, pulse generator 6, multiplier 7, sample size counter 8, accumulator adder 9 and output register 10, the proposed functional connection of voltmeter elements eliminates the need for complex blocks such as multiplier, divider and square root extractor. Due to this, the device has high reliability, has much smaller dimensions, weight and power consumption. The description contains examples of the implementation of the analog-digital converter 2, multiplier 7, and accumulating adder 9. 3 3. p., 3 sludge. (L 00 CO Cf3U.i

Description

The invention relates to instrumentation engineering and can be used in industrial process monitoring and control systems for measuring mean, average direct and rms (effective) values of a periodic voltage in the range of infra-low frequencies.

The aim of the invention is to simplify the voltmeter.

FIG. 1 shows a digital voltmeter circuit; in fig. 2 - a schematic digital voltmeter (fig. Block 1)

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ma analog-to-digital converter; 15 gistr 12. The first input of the shift register 12 is connected to the first output, and the output is connected to the first input of the adder 11. The second input of the shift register 12 is a control input, the second input of the adder 11 is an information input, and its second output - information output accumulative adder 9.

The 1-to-2-d converter 2 (Fig. 2) contains a comparator 13, a switch 14, a serial approximation register 15 and a digital-to-analog converter 16. The output of the comparator 13 is connected to the first input of the switch 14, the output of which is connected to the first input of the serial approximation register 15, the first output of which is the first output of the analog-to-digital converter 2. The second output of the register 15 is connected via a digital-to-analog converter to the second input of the comparator 13. The first input of the comparator 13 is informational the input of the analog-digital converter 2. The second input of the serial approximation register 15 is the second input of the analog-digital converter 2. The second and third inputs of the room fig. 3 is a control block diagram.

1) second servo amplifiers, analog-to-digital converter 2, period determining unit 3, shaper 4 frequencies, control unit 5, pulse generator 6, multiplier 7, sample volume counter 8, accumulator adder 9 and output register 10.

The input of Blode 1 of input amplifiers is the input of a voltmeter. The first output of the block 1 of the input amplifiers is connected to the first information input of the analog-digital converter 2, and the second output to the input of the block 3 for determining the period. The first input of the frequency generator 4 is connected to the first output of the period determining unit 3, and the second input to the first clock output of the generator 6 pulses. The first start input of the control unit 5 is connected to the output of the frequency former 4, and the second input is connected to the second output of the period determination unit 3. The third input and the first control output of the control unit 5 are connected respectively to the first output (Cycle stop) and the second input 30

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the house (start) of the analog-to-digital converter of the mutator 14 are respectively

2, the second output is from the control input of multiplier 7, the third output is from the control input of accumulating adder 9, the fourth output is from the control input of output register 10, and the fourth input is from the second clock output of the generator 6 pulses. The information output of the analog-digital converter 2 is connected to the information (second) input of the multiplier 7, the information output of which is connected to the information input of the accumulating adder 9. The third input of the analog-digital

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the third and fourth inputs of the analog-digital converter 2. The second output of the sequential approximation register 15 is the information output of the analog-digital converter 2.

The multiplier 7 is configured as a persistent storage device with an additional control input for switching measurement modes by switching different portions of the memory.

The control unit 5 (FIG. 3) contains seven triggers 17-23, the single-converter 2 is connected to the information output of accumulating adder 9, the fourth input is connected to the second control output of the control unit 5, the information output to the second input of output register 10, the output of which is It is the information output of a voltmeter. The fifth input and the fifth control output of the control unit 5 are connected respectively to the output and the input of the counter 8 of the volume B) of the assembly.

The accumulating adder 9 (Fig. 1) contains the adder 11 and the shear pe0

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the third and fourth inputs of the analog-digital converter 2. The second output of the sequential approximation register 15 is the information output of the analog-digital converter 2.

The multiplier 7 is configured as a persistent storage device with an additional control input for switching measurement modes by switching different portions of the memory.

The control block 5 (Fig. 3) contains seven triggers 17-23, one-time

RATOR 2A, four elements H 25-28, one element OR 29 and a counter 30. The first input of control unit 5 is the second input of trigger 18, its second input is the second input of trigger 17, its third input is one-shot input 24, its fourth the input is the second input of the trigger 21 and its fifth input — the second inputs of the two triggers 19 and 2-3 and the two elements AND 27 and 28. The first output of the control unit 5 is the output of the AND element 2 and the second output is the output of the trigger 20 The third output of the block 5 controls connect the outputs of the elements AND 26 and OR 29 and trigger 23, the fourth output output element and And 25 and Fifth output - output element And 26. The output of the trigger 17 is connected to the third input of the trigger 18. The output of the trigger 18 is connected to the third input of the trigger 19. The output of the trigger 19 is connected to the first input of the element 27. To the output of the one-vibrator 24 are connected the first inputs of three triggers 18, 19 and 20 and two eltsmen And 25 and 26. The second inputs of the elements And 26 and 25 are connected to the output of the trigger 22, the second input of which is connected to the output of the element And 26. The first inputs of the two triggers 17 and 22 and the element And 28 are connected to the trigger output 23. The output of the element is And 28 is connected | With the first inputs cient OR 29 and counter 30. The second input member

OR 29 is connected to the output of the element 25. The output of the trigger 21 is connected to the third input of the trigger 23 and the second input of the counter 30. The first inputs of the two triggers 21 and 23, the second input of the trigger 20 and the fourth inputs of the two triggers 18 and 19 are connected to the output of the counter 30. .

Digital voltmeter works as follows.

Before starting work, the measured signal parameter (mean square or rms voltage) is selected by switching on a specific memory area in the permanent memory of the multiplier at its additional input. A digital voltmeter does not require a preliminary installation, since at the end of each period of the measured signal after the next measurement result is issued, the device automatically returns to its original state.

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The measured voltage is nonaic f ml input unit 1 input amplifier, in which the voltage is brought to a certain level required for operation of the analog-digital converter 2, depending on the selected measurement range. The period determining unit 3 serves to convert the input periodic signal of a complex shape into a pulse train of the same period. Shaper 4 frequency produces pulses with a frequency f N / T, where N - o6beNf sample, i.e. the number of samples of instantaneous values of the measured voltage for one period, T, is the period of the measured voltage.

The shaper's operation 4 frequencies are clocked with a high-frequency signal from the generator of 6 pulses. The signals from the outputs of block 3 for determining the period, the fop of the four frequency generator and the generator 6 of pulses are the starting signals for the control block 5.

At the beginning of the next period of the input voltage, the signal from the output of the period determining unit 3 sets the trigger 17, the signal from the output of which permits the installation of the trigger 18. The nearest time pulse from the output of the frequency generator 4 sets the trigger 18, the signal from the output of which allows the installation of the trigger 19. The next time pulse from the generator 6 pulses install the trigger 19, the signal from the output of which allows the passage of the clock pulses of the generator 6 pulses through the element 27 on the analog-digital conversion 2 for azovatel

start register 15 sequential approximation. The sampling cycle of the instantaneous value of the measured voltage is carried out by the analog-digital converter 2. At the same time, the output signals of the comparator t3 are fed to the input of the sequential approximation register 15 through the switch 14. At the end of the sampling cycle, the sequential approximation register 15 generates a signal that, through the one-shot 24, resets the triggers 18 and 19. In addition, the signal from the output of the one-shot 24 through the AND 25 element goes to the counter 8 of the sample size and then through the element OR 29 to the accumulating adder 9 as a signal to accumulate to the previous sum of the next sample

 I a, the clock flow through AND 27 ceases. Since the trigger 17 remains in the set state, when the frequency generator 4 exits the next start pulse with the analog-digital converter 2, the next sampling cycle of the instantaneous value of the direct voltage will occur, and the accumulating adder 9 will add the next count to the previous sum and the sample volume counter 8 changes its state to 1. After the N-ro sample cycle, the sample volume counter 8 is reset and at the same time it issues a signal for the end of the sample, which triggers trigger 21, and a signal; from the chimney of which raspigg installation of the trigger 23 and the operation of the counter 30. Closing the impulse in time: 1-som from the generator of 6 pulses will set the trigger 23. The signal from the output of the trigger 23 will translate the shift transistor 12 into the shift mode and expand the clock pulses through olpme } t And 28 to the counting input of the counter 30 n further, through the element S1NI 29 to the clock input of the shear capacity 12. The same signal from the output of the trigger 23 resets the trigger points 17 and 22. The shift in the accumulated amount shift register 12 is performed for the purpose of normalizing, those. divide the amount by the number of samples. Since the shift to the right by one bit corresponds to division by 2, then the shift, for example, by 10 bits corresponds to division by 102A. The counter 30 counts the number of shift cycles and, at the end of the last clock cycle, generates a signal for the completion of the shift mode. Triggers 21 and 23 are reset by this signal and triggers 18, 19 and 20 are set. The signal from trigger output 19 is resolved

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clock pulses per register give the successive approximation of accumulator adder 15. The cycle for calculating the measurement result begins. The signal from trigger 20 switches switch 14 to the state where signals from the output of accumulating adder 9 are transmitted to the input of register 15 of successive approximation. The cycle of calculating the measurement result is completed by a signal from register 15 of sequential approximation, which resets Triggers 18, 19, and 20. Through the AND 26 element, this signal pushes the measurement result into 55

9, mine multiplier 7 or through it, but at the same time part of the memory volume of the permanent storage device is programmed as a repeater address for accumulating the sum and as an address inverter for calculating the measurement result. Such a solution allows not to change the algorithm of operation of unit 5 of the control when measuring various signal parameters.

The proposed digital voltmeter, preserving all the performance characteristics of the known instrument F7228, is much simpler than it, since you

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the output register 10 and resets the accumulating adder 9. On the falling edge, the signal from the output of the I 26 sets the trigger 22 and the control unit 5 switches to the standby mode for the next trigger pulse from the period determination unit 3.

The multiplication of a multiplier 7 in a digital voltmeter pulsates a persistent storage device, part of the storage space of which is programmed as a table of squares, when in the mode of measuring the RMS value of a signal, the code at the output of it is equal to the square of the set address. The address is the output code of the register 1 J 1 after; 1. orb.

Extracting the square root of

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By entering the input, the multiplier 7 transits / reads to the memory area where the programmer is (1nan table of squares in 1-1 codes. Register 15 followers (1st G1p1-range by the known a. IrijpirrNiy selects such a number ;. whose square is equal to or 6jni3oK to the number in the SPDIGS1VOM register 12. At the same time, the adder 1 1 compares the number in the shift register 12 and the squares of the numbers from the output of the sequential approximation register 15. The output signal of the higher-order transfer of the adder 11 characterizes the result of the comparison and is supplied when removed chenii square root pas through the switch 14 first Infor- mation) 1st input ret istra 15 posledo- vatelpog of approximation.

When measuring the mean value of the voltage, the samples of the instantaneous values of the voltage from the output of the register 1 5 successively approximate

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9, mine multiplier 7 or through it, but at the same time part of the memory volume of the permanent storage device is programmed as an address repeater for accumulating the sum and as an address inverter for calculating the measurement result. Such a solution allows not to change the algorithm of operation of unit 5 of the control when measuring various signal parameters.

The proposed digital voltmeter, preserving all the operational characteristics of the well-known instrument F7228, is much simpler because it is performed without complex digital blocks of the resident, divider and digital K1 adrat root. By reducing the hardware costs for the implementation, this digital voltmeter has greater reliability, significantly smaller dimensions, weight and power consumption, which will try its consumer value.

Claims (4)

1. A digital voltmeter containing a block of input amplifiers, the input of which is the input of a voltmeter, the first output of the block of input amplifiers to the connector with the first information input of the analog-digital converter, and the second output with the input of the period determining unit, the frequency driver, the first input of which connected to the first output of the period determining unit, and the second input to the first clock output of the pulse generator, the start input of the control unit is connected to the output of the frequency driver, the second input to the second output the period determining unit, the third input of the control unit is connected to the output of the analog-digital converter cycle stop, the first output of the control unit is connected to the input of the start of the analog-digital converter, and the second output is connected to the control input of the multiplier, the third output is connected to the control input of the accumulating adder , the fourth output is from the control input of the output register, the second clock output of the pulse generator is connected to the fourth input of the control unit, the second output of the analog-digital converter is connected to the information A multiplex input, the output of which is connected to the information input of the accumulating adder, the output of the output register is a voltmeter output, characterized in that, for the sake of simplicity, the second output of the control unit is connected to the control input of the analog-digital converter, the second information input of which is connected to output accumulating sum. ig 15 3377918 the mater, the second output of the analog-digital converter is connected to the information input of the output register, the fifth input and the output of the control unit of the controller with the corresponding input and output of the sample volume counter. 2. A voltmeter according to claim 1, that is, that the analog-to-digital converter contains a comparator, a digital-to-analog converter, a serial approximation register, and a switch, with the output of the comparator connected to the first input of the switch, whose output connected to the first input of the serial approximation register, the first output of which is BI IXOAOM; the cycle of the analog-to-digital converter is stopped, and the second output is connected to the second input of the comparator, the first input of which is a digital-to-analog converter; The first information input of the analog-to-digital converter, the second input of the serial approximation register is the starting input of the analog-digital converter, the second and third inputs of the switch are the second information and control inputs of the analog-digital converter, the second output of the serial approximation register is connected with the second analog-digital output 20 thirty 35 converter I 3. Voltmeter according to Claim. 1, O TL & 0 five 0 all that is made in the form of the fact that the multiplier is a persistent storage device with an additional control input. 4. A voltmeter according to claim 1, characterized in that the accumulating adder comprises an adder, the first inputs and outputs of which are connected to the corresponding output and the first input of the shift register, the second inputs of the shift register and adder being respectively the control and information inputs of the accumulating adder, and the second output of the adder is the information output of the accumulating adder. Oms n5 / g. 5 FIG. 2 ofTj 5 / t 5 K6l.9, Yu