SU1368797A1 - Device for measuring a.c.voltage frequency - Google Patents

Abstract

The invention relates to electrical and radio measurements. The device comprises an analog-digital converter 1, a generator of 2 pulses, memory registers 4-6, delay blocks 8 and 9, an adder 11, a divider 12, a digital-analog converter 13 and a functional converter. 14. The introduction of the subtractor 3, the memory register 7 and the delay unit 10 expands the functionality of the device. Thus, it becomes possible to measure the frequency of an alternating voltage by the results of four counts of instantaneous values of voltages and, and, and and and, taken at reference intervals, followed by finding the track of the differences of instantaneous values di, U ,, bU U - Uj and li, U, which eliminates the influence of the constant component of the input signal. 1 il. c (O (/: s

Description

The invention relates to the field of electrical measurements and can be used when measuring the frequency of a sinusoidal voltage in the presence of a constant component of any sign in its composition.

The purpose of the invention is to expand the functionality.

The drawing shows a block diagram of the device.

The device contains an analog-digital converter 1 (A1DP), a pulse generator 2, a subtractor 3, memory registers 4-7, delay blocks 8-10, an adder 11, a divider 12, a digital-analog converter 13 (D / A converter), and a functional converter 14.

The signal input of the ADC 1 is the input of the device. The output of the pulse generator 2 is combined with the control input A1SCH 1, the input of the delay block 10 and the control input of the memory register 7, the output of which is connected through the series-connected adder 11, divider 12 and D / A converter 13 to the input of the function converter 14. The output of the ADC 1 is connected to the first input is read out 1 3 directly and through the memory register 4 to the second input of the subtractor 3, the output of which is connected to the memory register 7 and the second input of the divider through serially connected memory registers 5 and 6 with a control input of memory register 6 and through series-connected delay blocks 9 and 8 connected to a control input of memory register 4, the output of delay block 9 connected to a control input of memory register 5, the output of which is connected to the second input of the adder eleven.

The device works as follows.

At the output of the pulse generator 2, a sequence of short clock pulses is formed, the interval between which is equal to the reference time interval D. The first clock pulse from the generator of 2 pulses triggers the ADC 1, which converts the instantaneous value of the controlled alternating voltage U, which exists at the time of the clock pulse, into a digital code corresponding to this value, and supplies it to the register 4 TI and at the first input of the reader 3. At the same time, this current clock pulse arrives at the control input of the register

7, recording information from the output of register 6 of memory to it, as well as to the input of block 10 of delay, from the output of which a delayed pulse arrives at the control input of register 6 of memory, recording information from the output of register 5 of memory to it, and to the input of the block 9 delay, the output of which is secondary

the delayed clock pulse is applied to the control input of the memory register 5, recording information from the output of the subtractor 3 into it, and to the input of the block

8 latency Since the release of the last

the third time the delayed pulse is applied to the control input of the register 4 of the memory, the output of which is connected to the second input of the subtractor 3, recording information from the output of the A / D converter 1 into it.

The next (second) clock pulse from the pulse generator 2 restarts the ADC 1, at the output of which a digital code appears, the value of which corresponds to the instantaneous

U value of controlled variable voltage. Since at this time, at the output of memory register 4, there is a digital code corresponding to the instantaneous value U, variable

voltage, then at the output of the subtractor 3 there is a difference of these two values bU, U ,. After passing the second clock pulse through the blocks of 10.9 and 8 first delays

the difference between the two instantaneous values of the monitored voltage is written to the memory register 5 and appears at one of the inputs of the adder 1 1, and the instantaneous value U of the alternating voltage is written to the memory register 4.

After passing the third clock pulse from the generator 2 pulses, the second difference of two instantaneous values of alternating voltage and - Uj - U appears at the output of memory register 5, the first difference UU, at the output of memory register 6,

memory register 4 — instantaneous value of Uj.

After passing through the fourth pulse from the pulse generator 2, the third difference of two instantaneous values of the alternating voltage AU, j and, appears at the output of the register 5 of the memory, the second difference of the two instantaneous values of bU, and at the output of register 7 of memory there is the first difference of two instantaneous values MJ ,, Since the outputs of registers 7 and 5 of memory are connected to the inputs of adder 11, and the output of register 6 of memory is connected to the second input of divider 12, then at the output of adder 11 after a fourth clock pulse appears the sum of the two differences of the instantaneous values of uU, + iU and the output of de .0 li, + di,

Letter 12 - quotient Cg- in video-uUj

de digital code, - This code Converts the DAC 13 to an analog value, and the function transducer 14

implements the function & u, + li.

arccos

2 ir-u ie on his way out

is the value of the frequency of the controlled alternating voltage f.

I

The device measures the frequency of the alternating voltage based on the results of four readings of the instantaneous values of this voltage, U ,, -, taken at standard intervals of time D, and the subsequent finding of the three differences of instantaneous values of bo, Uj - and, leagues and, - Uj HAUj U - Uj, which eliminates the effect

five

0

five

Claims (1)

the constant component of the input signal. Invention Formula A device for measuring the frequency of an alternating voltage, containing in series the first, second, third registers of memory, summator, divider, digital-to-analog converter and functional converter whose output is the output of the device, as well as the analog-to-digital converter controlling input which is combined with the output of the pulse generator, the control input of the third memory register and the input of the first delay unit, and the output of the first delay unit is combined with the control input of the second register memory and input of the second delay unit, the output of which is connected to the control input of the first memory register, characterized in that, in order to expand its functionality, the subtractor, the fourth memory register and the third delay unit, input which is connected to the output of the second delay unit, and the output to the control input of the fourth memory register, the output of the analog-digital converter is connected to the first input of the subtractor directly and through the fourth memory register to the second input Ate, the output of which is connected to the input of the first memory register.