CN1450341A - Method for detecting industrial frequency ac electric period change - Google Patents
Method for detecting industrial frequency ac electric period change Download PDFInfo
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- CN1450341A CN1450341A CN 03116540 CN03116540A CN1450341A CN 1450341 A CN1450341 A CN 1450341A CN 03116540 CN03116540 CN 03116540 CN 03116540 A CN03116540 A CN 03116540A CN 1450341 A CN1450341 A CN 1450341A
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Abstract
The invention is a method of catching the periodic variation of the industrial frequency AC, including the catching circuit, consisting of the rectifier, the constant current converter and the current comparer. It includes the following steps: 1. rectify the AC and output it to the converter; 2. when the energy input into the converter reaches the preset voltage value, the converter outputs constant current I0; 3. input I0 on the input ends of the current comparer and compare with the reference current preset by the converter; the square wave output by the comparer is an industrial frequency AC periodic variation signal, which is input into microprocessor for the following processing. It can eliminate the interference signals in the electric network and precisely catch the periodic variation.
Description
Technical field
The present invention relates to the method for catching that a kind of industrial-frequency alternating current cycle changes, especially relate to a kind of based on current ratio, can eliminate the method for catching that industrial-frequency alternating current cycle that the electrical network empty voltage disturbs changes.
Background technology
The power frequency interference noise is a kind of interference noise common in the signal processing.It shows as, and the stack frequency is the undesired signal of 50Hz on the useful signal.The cycle that needs to catch industrial-frequency alternating current in electromagnetic flowmeter realizes low frequency square wave excitation technology (for example, application for a patent for invention number 99113868,94106979,87101677,85106293) and suppresses the power frequency interference noise.Said method must be changed to foundation to catch the industrial-frequency alternating current cycle, offsets the power frequency of scurrying into signal circuit fully in the time of just being implemented in positive and negative excitation Synchronous Sampling of Periodic Signal and disturbs.Existing seizure industrial-frequency alternating current cycle changing method adopts the level signal manner of comparison to realize more.Be specially: industrial-frequency alternating current is sent into level comparator and reference voltage relatively, obtain the square wave identical with the industrial-frequency alternating current cycle at the output terminal of comparer, the variation in industrial-frequency alternating current cycle is the variation of square-wave cycle.Because this method only adopts level signal relatively, when external interference (as the electromagnetic flowmeter switch power module etc.) makes the empty voltage of the various amplitudes of stack on the input voltage, the level comparator output waveform just may just occur overturning when input voltage arrive reference value by mistake.Like that, be subjected to the level comparative approach of empty voltage disturbing effect can not accurately capture the variation in industrial-frequency alternating current cycle.
Summary of the invention
The objective of the invention is to solve existing detection industrial-frequency alternating current cycle variation, adopt the level signal relative method to be subject to the shortcoming that empty voltage disturbs, and the method for catching that a kind of industrial-frequency alternating current cycle changes is provided, this electric current comparative approach based on energy can accurately be caught the variation of industrial-frequency alternating current cycle.
The object of the present invention is achieved like this: the method for catching that a kind of industrial-frequency alternating current cycle changes, the catching circuits that comprises the industrial-frequency alternating current cycle of forming by rectifier, constant current converter, current comparator of realizing this method, it is characterized in that this method may further comprise the steps at least:
A. industrial-frequency alternating current is undertaken outputing to the constant current converter after the rectification by rectifier;
B. reach the magnitude of voltage of setting when the energy of input constant current converter, constant current converter output steady current I
0
C. import the continuous current I that exports by the constant current converter at the input end of current comparator
0Establish with the constant current converter
Fixed reference current compares; Current comparator output square wave is the signal that changes in the industrial frequency AC cycle,
Again this signal input microprocessor is carried out subsequent processes work.
The method for catching that the above-mentioned industrial-frequency alternating current cycle changes, wherein, the pressure reduction between the U0 of described constant current converter input end and the constant current converter end is greater than 3V; The U of constant current converter
0Pressure reduction between end and the output terminal remains on 1.25V.
The method for catching that the above-mentioned industrial-frequency alternating current cycle changes, wherein, the reference current value that described current comparator is set is the conducting current value of current comparator.
A kind of catching circuits that is used to realize the industrial-frequency alternating current cycle of said method, comprise rectifier, constant current converter, current comparator, it is characterized in that: the input end of described rectifier is connected with power frequency AC, its output terminal is connected with the input end of constant current converter and the input end of current comparator respectively, and the output terminal of described constant current converter is connected with the input end of current comparator.
The catching circuits in above-mentioned industrial-frequency alternating current cycle, wherein, described rectifier is a commutation diode D1, the positive pole of this pipe connects AC power, exports after this diode half-wave rectification.
The catching circuits in above-mentioned industrial-frequency alternating current cycle, wherein, described constant current converter is made up of an integrated constant current source chip U1 and a resistance R 1, and the input end 1 of constant current converter is connected with the negative pole of commutation diode D1, and the output terminal 3 of constant current converter is connected resistance R 1 with end between 2.
The catching circuits in above-mentioned industrial-frequency alternating current cycle, wherein, described current comparator is that a photocoupler U2 and a resistance R 2 are formed, and the input end 1 of photocoupler U2 is connected with the output terminal of constant current converter U1, the resistance R 2 of connecting between the output terminal 3 of photocoupler and the+5V power supply.
The present invention is owing to adopted above-mentioned technical scheme, make it compared with prior art, have following advantage and good effect: the present invention is owing to adopt the electric current relative method, in the catching circuits in the industrial-frequency alternating current cycle that this method of realization is provided with, be provided with constant current converter and current comparator, when the external world produces the empty voltage undesired signal, to importing to such an extent that the influence of alternating current energy is minimum, output current size influence to the constant current converter is very faint, can not change the state of constant current converter output current, be difficult to make the output square wave of current comparator to produce the mistake upset, thereby accurately catch the variation of industrial-frequency alternating current cycle.
Description of drawings
Fig. 1 is the process flow diagram of the method for catching of industrial-frequency alternating current cycle variation
Fig. 2 is the circuit block diagram that is used to realize the method for catching that the industrial-frequency alternating current cycle changes.
Fig. 3 is the circuit theory diagrams that are used to realize the method for catching that the industrial-frequency alternating current cycle changes.
Fig. 4 is circuit input and output voltage, the current waveform figure that is used for the method for catching of industrial-frequency alternating current cycle variation.
Specific implementation method
Referring to Fig. 1, the method for catching that a kind of industrial-frequency alternating current cycle changes comprises the catching circuits in the industrial-frequency alternating current cycle of being made up of rectifier, constant current converter, current comparator of this method of realization it is characterized in that this method may further comprise the steps at least:
A. industrial-frequency alternating current is undertaken outputing to the constant current converter after the rectification by rectifier;
B. reach the magnitude of voltage of setting when the energy of input constant current converter, constant current converter output steady current I
0
C. import the continuous current I that exports by the constant current converter at the input end of current comparator
0Establish with the constant current converter
Fixed reference current compares; Current comparator output square wave is the signal that changes in the industrial frequency AC cycle,
Again this signal input microprocessor is carried out subsequent processes work.
The extraneous empty voltage undesired signal that produces, though the alternating voltage amplitude is produced considerable influence, but very big because of its signal internal resistance, energy is very little, so very faint to the influence of the output current of V/I constant current converter size, be difficult to make the output square wave of current comparator to produce the mistake upset.This has just been avoided using the level signal relative method to be subject to the phenomenon that the mistake upset appears in the undesired signal influence.
Referring to Fig. 2, a kind of catching circuits that is used to realize the industrial-frequency alternating current cycle of said method, comprise rectifier D1, constant current converter U1, current comparator U2, the input end of rectifier U1 is connected with power frequency AC, its output terminal is connected with the input end of constant current converter U1 and the input end of current comparator U2 respectively, and the output terminal of described constant current converter U1 is connected with the input end of current comparator U2.
Referring to Fig. 3, described rectifier is a commutation diode D1, and the positive pole of this pipe connects AC power, exports after this diode half-wave rectification.Described constant current converter U1 is made up of an integrated constant current source chip (model is LM317) and a resistance R 1, and the input end 1 of constant current converter is connected with the negative pole of commutation diode D1, the output terminal 3 of constant current converter with hold 2 between be connected resistance R 1; Current comparator is a photocoupler U2 (model is 521) and a resistance R 2 is formed, and the input end 1 of photocoupler U2 is connected with the output terminal of constant current converter U1, the resistance R 2 of connecting between the output terminal 3 of photocoupler and the+5V power supply.
Power frequency ac voltage Uin input diode D1 carries out half-wave rectification to industrial-frequency alternating current; When Uin is the positive voltage that rises gradually, diode D1 forward conduction; When the energy from input end 1 input of constant current converter acquires a certain degree, the voltage difference Vi-Vo between the Vi input end 1 that makes the constant current converter and the Vo end 3 is greater than 3V, and the Vo of constant current converter end 3 and ADJ hold the voltage difference Vref between 2 can remain on 1.25V.Like this, the constant current converter has constant output current Io=Vref/R2; R2=120 ohm, Io are about 10 milliamperes, can make the photocoupler conducting, and output voltage U out just is 0.When power frequency ac voltage Uin is the positive voltage that descends gradually, the energy that power supply is supplied with the constant current converter reduces gradually.When voltage difference Vi-Vo less than 3V, Vref is 0, then constant current converter no current output, photocoupler disconnects, output voltage U out remains 5V.When power frequency ac voltage Uin is a negative voltage, diode D1 ends, no current output, and output voltage U out remains 5V.
Referring to Fig. 4, in the present embodiment, from the waveform of photocoupler output voltage U out as can be seen, the cycle of industrial-frequency alternating current is t2-t1.Conducting electric current as the photocoupler of current comparator is exactly a reference current value, when having only the power supply energy of importing the constant current converter to reach certain value, the constant current converter could be exported the permanent steady electric current I o greater than the conducting electric current, makes the level Uout of output terminal produce saltus step.And the very little undesired signal of energy cuts little ice to the output current Io of constant current converter, just can not change the state of output voltage U out.Photocoupler output voltage U out can output in the microprocessor, and the mistiming of detecting two rising edge saltus steps can be determined the cycle and the variation thereof of industrial-frequency alternating current.
So to sum up, the industrial-frequency alternating current cycle that the present invention proposes changes method for catching and is used to realize the catching circuits in the industrial-frequency alternating current cycle of this method, can eliminate undesired signal the industrial-frequency alternating current cycle is changed the influence of capture-process, thereby improve the accuracy of industrial-frequency alternating current cycle seizure.
Claims (7)
1. the method for catching that changes of industrial-frequency alternating current cycle comprises it is characterized in that the catching circuits in the industrial-frequency alternating current cycle of being made up of rectifier, constant current converter, current comparator of this method of realization, this method comprise at least with
Following step:
A. industrial-frequency alternating current is undertaken outputing to the constant current converter after the rectification by rectifier;
B. reach the magnitude of voltage of setting when the energy of input constant current converter, constant current converter output steady current I
0
C. import the continuous current I that exports by the constant current converter at the input end of current comparator
0Establish with the constant current converter
Fixed reference current compares; Current comparator output square wave is the signal that changes in the industrial frequency AC cycle,
Again this signal input microprocessor is carried out subsequent processes work.
2. the method for catching that the industrial-frequency alternating current cycle according to claim 1 changes is characterized in that, the pressure reduction between the U0 end of described constant current converter input end and constant current converter is greater than 3V; The U0 end of constant current converter and the pressure reduction between the output terminal remain on 1.25V.
3. the method for catching that the industrial-frequency alternating current cycle according to claim 1 changes is characterized in that, the reference current value that described current comparator is set is the conducting current value of current comparator.
4. catching circuits that is used to realize the industrial-frequency alternating current cycle of said method, comprise rectifier, constant current converter, current comparator, it is characterized in that: the input end of described rectifier is connected with power frequency AC, its output terminal is connected with the input end of constant current converter and the input end of current comparator respectively, and the output terminal of described constant current converter is connected with the input end of current comparator.
5. the catching circuits in industrial-frequency alternating current cycle according to claim 4 is characterized in that, described rectifier is a commutation diode (D1), and the positive pole of this pipe connects AC power, exports after this diode half-wave rectification.
6. the catching circuits in industrial-frequency alternating current cycle according to claim 4, it is characterized in that, described constant current converter is made up of an integrated constant current source chip (U1) and a resistance R 1, the input end 1 of constant current converter is connected with the negative pole of commutation diode D1, and the output terminal 3 of constant current converter is connected resistance R 1 with end between 2.
7. the catching circuits in industrial-frequency alternating current cycle according to claim 4, it is characterized in that, described current comparator is that a photocoupler (U2) is formed with a resistance R 2, the input end 1 of photocoupler (U2) is connected with the output terminal of constant current converter (U1), the resistance R 2 of connecting between the output terminal 3 of photocoupler and the+5V power supply.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB031165400A CN100473953C (en) | 2003-04-22 | 2003-04-22 | Method for detecting industrial frequency AC electric period change |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB031165400A CN100473953C (en) | 2003-04-22 | 2003-04-22 | Method for detecting industrial frequency AC electric period change |
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| CN1450341A true CN1450341A (en) | 2003-10-22 |
| CN100473953C CN100473953C (en) | 2009-04-01 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNB031165400A Expired - Fee Related CN100473953C (en) | 2003-04-22 | 2003-04-22 | Method for detecting industrial frequency AC electric period change |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101667786B (en) * | 2009-09-27 | 2012-05-23 | 上海大学 | System for catching alternating current periodic variation and method thereof |
| CN104765299A (en) * | 2015-02-03 | 2015-07-08 | 浙江捷昌线性驱动科技股份有限公司 | Alternating current vibration motor amplitude control method and control circuit and massage bed |
| CN112050870A (en) * | 2020-08-20 | 2020-12-08 | 长江武汉航道工程局 | Curve reduction anti-interference measuring device and method thereof |
-
2003
- 2003-04-22 CN CNB031165400A patent/CN100473953C/en not_active Expired - Fee Related
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101667786B (en) * | 2009-09-27 | 2012-05-23 | 上海大学 | System for catching alternating current periodic variation and method thereof |
| CN104765299A (en) * | 2015-02-03 | 2015-07-08 | 浙江捷昌线性驱动科技股份有限公司 | Alternating current vibration motor amplitude control method and control circuit and massage bed |
| CN112050870A (en) * | 2020-08-20 | 2020-12-08 | 长江武汉航道工程局 | Curve reduction anti-interference measuring device and method thereof |
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| Publication number | Publication date |
|---|---|
| CN100473953C (en) | 2009-04-01 |
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Granted publication date: 20090401 Termination date: 20120422 |