SU1679399A1 - Meter of amplitude of harmonic signal - Google Patents

Abstract

This invention relates to electrical measuring technology. The purpose of the invention is to improve the accuracy and expansion of the frequency range of measurement. The proposed meter contains a source 2 of the reference voltage of a direct current, a digital voltmeter 3, an adder 4, a computational unit 7. The introduction of an integrator 5, a zero-body 6, a control unit 8 ensures the elimination of errors associated with determining the moment of ceasing the change of the sign of the integral values of the sum signal and allows measurement of signals with a frequency greater than 50 Hz. 1 hp f-ly, 1 ill.

Description

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This invention relates to electrical measuring technology.

The purpose of the invention is to improve the accuracy and expansion of the frequency range of measurement.

The drawing shows a structural diagram of the meter.

The meter contains an input for connecting the source 1 of the measured signal, the source 2 of the adjustable reference DC voltage, the digital voltmeter 3. the adder 4 analog signals, the integrator 5, the zero-organ b, the computing unit 7 and the control unit 8, performed on the first trigger 9, a quartz generator of 10 pulses, the first 11 and second 12 pulse drivers, the first 13 and second 14 synchronizers, the second 15 and third 16 triggers, the first - five coincidence elements 17–21, the 22 frequency divider, the first counter 23, third 24 and fourth 25 pulse shaper on the falling edge, the first 26 and the second 27 elements OR, the second 28 and the third 29 counters.

Computing unit 7 is implemented on the fourth trigger 30, the sixth coincidence element 31, the fourth counter 32, the decoder 33, the multiplexer 34, and the electronic computer (PC) 35.

The device input is connected to the first input of the adder 4 and the input of the imaging unit 11, forming the first input of the unit 8. The source 2 output is connected to the second input of the adder 4 and the input of the voltmeter 3. The output of the adder 4 through the integrator 5 is connected to the input of the zero-body 6. Device Start connected to the S-input of the trigger 9, which is the third input of the block 8, to the installation input of the counter 23, to the reset inputs of the counters 28 and 29 and the first inputs of the OR elements 26 and 27, the outputs of which are connected to the R-inputs of the triggers 15 and 16, respectively. One of the outputs of the imaging unit 11 is connected to the first inputs of the elements 19 and 20 coincidence, and the other output is connected to the second input of the synchronizer 13. The output of the generator 10 is connected to the input of the imaging unit 12, with the third inputs of the synchronizers 13 and 14 with the first inputs of the elements 17 and 18 and clock the output of block 8, which is connected to the first input of matching element 31, which is a clock input of block 7.

One of the outputs of the imaging unit 12 is connected to the control input of the integrator 5 and the first input of the element 21, and the second output is connected to the second input of the synchronizer 14. The first inputs of the synchronizers 13 and 14

and the R input of the trigger 9 is connected to the second input of the block 8 and connected to the output of the zero organ 6 and to the control input of the digital voltmeter 3, the output of which is connected to the first input of the multiplexer 34, which is the first input of the block 7. The output of the trigger 9 is connected to the second input of the element 19, the output of which through the divider 22 is connected to the subtraction input of the counter 23, the output of which is the first output of the block 8 and connected to the control inputs of the source 2. The outputs of the synchronizers 13 and 14 are connected to the S-inputs of the flip-flops 15 and 16, respectively.

The output of the trigger 15 is connected to the second inputs of the elements 17 and 20, the output of the element 17 is connected to the addition input of the counter 28, and the output of the element 20 is connected to the input of the driver 24, the output of which is connected to the second input of the element OR 26 and the S input of the trigger 30, which is the control input of the unit 7. The R input of the trigger 30 is connected to the output of the counter 32. The output of the trigger 30 is connected to the second input of the element 31, the output of which is connected to the addition input of the counter 32 and the synchronous computer 35. The output of the trigger 16 is connected to the second inputs of the elements 18 and 21. The output of element 18 com. The output of element 21 is connected via shaper 25 to the second input of the element OR 27. The outputs of counters 28 and 29, which are the second and third outputs of block 8, are connected to the second and third inputs of multiplexer 34, respectively, which are the second and the third inputs of the unit 7. The control inputs of the multiplexer 34 are connected to the outputs of the decoder 33, the inputs of which are connected to the outputs of the counter 32. The outputs of the multiplexer 34 are connected to the inputs of the computer 35.

The meter works as follows.

In the initial state, the adder 4 receives the measured signal Ux from source 1 and the reference signal U0 from source 2, and Uo Ux modulo, which is ensured by applying a code signal from counter 23 to the inputs of source 2 corresponding to the maximum value of its output voltage wives The latter is provided by writing 1 to all bits of the counter 23. In this case, the signal at the output of the adder 4 oscillates without changing the sign of the signal. At the same time, the signal Ux is fed to the input of the imaging unit 11, which ensures the formation of both a periodic sequence of pulses of duration corresponding to the period of the measured signal and the pulses corresponding to the leading edge of these pulses. The pulses with a duration equal to the period of the measured signal are fed to the inputs of the elements 19 and 20 coincidence, which are in the closed state, and the pulses corresponding to the leading edge of these pulses are fed to one of the inputs of the synchronizer 13.

The input of the imaging unit 12 receives pulses from the output of the quartz oscillator 10, according to which the imaging unit 12 generates pulses of a periodic sequence with a duration equal to the integration cycle, as well as pulses corresponding to their leading edges.

Pulses with a duration equal to the integration cycle arrive at one of the inputs of the coincidence element 21 and the control input of the integrator 5, ensuring periodic integration of the signal from the output of the adder 4. The coincidence element 21 is in the closed state. The pulses corresponding to the leading edge of the pulses, with a duration equal to the integration cycle, arrive at one of the inputs of the synchronizer 14.

The Start command, which is fed to the S input of the trigger 9, opens the coincidence element 19, and pulses with a duration equal to the period of the measured signal are fed to the input of the frequency divider 22, the division factor of which is set in advance from the condition of the required frequency of changing the source code 2, namely: Tcodfx, where fx is the frequency of the signal Ux, and the value of Uo at the output of source 2 decreases from a certain maximum value to an integral value of the total signal of zero value. At this moment, the zero-organ 6 generates an output signal, by which the trigger 9 returns to the zero state and stops the arrival of counting pulses at the input of the counter 23. At the same time, the output signal of the zero-organ b goes to the control input of the digital voltmeter 3 to measure the output the signal from source 2 and to the inputs of the synchronizers 13 and 14. Synchronizers 13 and 14 signal the output from the zero-organ 6 to pass to the S-inputs of the triggers 15 and 16 successive pulses from the outputs of the formers 11 and 12, through which the outputs of the triggers 15 and 16, a high potential is established opening the elements 17, 20 and 18, 21 matches, respectively. In this case, a pulse packet is received at the input of the counter 28, corresponding to the duration of the period of the measured signal, and at the input of the counter 29, a packet of pulses is received, corresponding to the duration of the integration cycle.

Thus, the conversion of the duration of the measured signal and integration cycle into digital codes, which arrive at the information inputs of the computing unit 7, is carried out. Simultaneously with the conversion of the time interval — the code, pulses are formed on the falling edge of the pulses of the measured interval 24 and 25 pulses, which, via the OR 26 and 27 elements, return the triggers 15 and 16 to the zero state. The input signal of the generator 24 determines the moment when the measurement ends and goes to the control input of the computing unit 7 to receive measurement information and then calculate the desired amplitude value using the formula

- Uc

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I x

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where Uo is the result

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measurement with a voltmeter 3; - - relation

the duration of the integration cycle and the period of the measured signal.

However, considering that the measurement results are digital codes, the calculation formula can be represented as follows:

3.141592

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Sin 3.141592

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The computer 35 in block 7 is in the initial state in standby mode. The End of Measurement signal, which comes from the output of shaper 24, enters the S input of trigger 30, a coincidence element 31 is opened, and the pulses from its output arrive at the input of counter 32 and, as a sync pulse, the input of the computer 35. The decoder 33 decrypts the changing code from the output of the counter 32, which controls the flow of measurement information through the multiplexer 34 to the information input of the computer 35. In this case, the measurement information is recorded in the memory of the computer 35 and then the program calculates the desired amplitude value. Upon completion of the input into the computer 35 of the measuring infarmation by the output signal of the counter 32, the trigger 30 returns to the zero state and the flow of the clock pulses to the input of the computer 35 stops.

The meter allows stable and highly accurate determination of the achievement of the integral value of the total signal of the zero level, which is determined only by the error of the null organ b triggering threshold, which, in the absence of a change in the sign of the integral value of the total signal, greatly simplifies the implementation of the measurement automation process. The meter provides a wide frequency range of the measured signals, since the ratio of the integration cycle duration and the period of the measured signal period can be significantly extended towards high frequencies (50 Hz).

Claims (2)

Claim 1, the amplitude meter of a harmonic signal containing an adder, the first input of which is connected to the input of the device, and the second input - to the reference voltage source of direct current and the first input of the digital voltmeter, the output of which is connected to the first input of the computing unit, that, in order to increase the accuracy and expand the measurement frequency range, an integrator, a null organ and a control unit, the first input of which is connected to the device input, the output of the adder through the sequence The separately connected integrator and null organ are connected to the control input of a digital voltmeter and, to the second input of the control unit, the third input of which is connected to the Start input of the device, the first output to the control input of the DC reference source, the second and third outputs connected to the second and third inputs of the computing unit, clock and second control outputs to the clock and control inputs of the computing unit, and the first control output is connected to the integrator control input, and the control unit The controller includes a crystal oscillator, two pulse drivers, two synchronizers, three triggers, five coincidence elements, four pulse generators, two OR elements, a pulse counter gri and a frequency divider, the third input of the control unit is connected to the S input of the first trigger, the installation input of the first counter, with the reset inputs of the second and third counters and the first inputs of the OR elements, the outputs of which are connected to the R inputs of the second and third triggers, respectively, the first input of the control unit connected input of the first pulse shaper, a first output connected to the first inputs of the third and fourth members coincidence, and second The output to the second input of the first synchronizer, the crystal oscillator output 0 pulses are connected to the input of the second pulse generator, with the third inputs of the synchronizers, with the first inputs of the first and second match elements and with the clock output of the control unit, the first output of the second pulse driver are connected to the first control output of the control unit and the second output is connected to the second input of the second synchronizer; the first inputs of the synchronizers and the R input of the first trigger are connected to the second input of the control unit; the output of the first trigger is connected to the second the input of the third coincidence element, the output of which is connected via the frequency divider is connected to the first counter and the synchronizer outputs connected to the second and third triggers, respectively; the output of the second trigger is connected to the second inputs the first and fourth elements of the match, the output of the first element of the match is connected to the input of the addition of the second 5 counter, the output of the fourth element of the match through the third pulse shaper is connected to the second input of the first element OR and the second control output of the control unit, the output of the third 0 trigger connected to the second inputs of the second and fifth elements of the match, the output of the second element of the match is connected to the input of the third counter, the output of the fifth element of the match through the fourth pulse shaper is connected to the second input of the second element OR, the outputs of the second and third counters are connected to the second and the third output of the control unit, respectively. 0 2. The meter according to claim 1, from l and h yu shchi with the fact that the computing unit contains a multiplexer, the outputs of which are connected to the inputs of the electronic computing machine, the synchronous input of which is connected to 5 by the output of the coincidence element and the addition input of the counter, the outputs of the counter are connected via a decoder to the control inputs of the multiplexer, the first, second and third inputs of which are connected to the first, second and third inputs of the calculator The S-input of the trigger is connected to the upstream input of the coincidence element, the forward input of the computational unit, the input of which is connected to the clock input R-input - with the counter output, and the output - with the input of the computing unit.