CN113917229A - Power frequency interference elimination method for power frequency detection circuit - Google Patents
Power frequency interference elimination method for power frequency detection circuit Download PDFInfo
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- CN113917229A CN113917229A CN202111187166.5A CN202111187166A CN113917229A CN 113917229 A CN113917229 A CN 113917229A CN 202111187166 A CN202111187166 A CN 202111187166A CN 113917229 A CN113917229 A CN 113917229A
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- power frequency
- square wave
- resistor
- wave signal
- circuit
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R23/00—Arrangements for measuring frequencies; Arrangements for analysing frequency spectra
- G01R23/02—Arrangements for measuring frequency, e.g. pulse repetition rate; Arrangements for measuring period of current or voltage
- G01R23/10—Arrangements for measuring frequency, e.g. pulse repetition rate; Arrangements for measuring period of current or voltage by converting frequency into a train of pulses, which are then counted, i.e. converting the signal into a square wave
Abstract
The invention relates to a method for detecting power frequency in the industry of instruments and meters, in particular to a power frequency interference elimination method for a power frequency detection circuit; wherein this power frequency detection circuit includes: an induction part for inducing an alternating magnetic field of alternating current to obtain an induced electromotive force signal; the waveform adjusting circuit is electrically connected with the induction part and used for converting the induced electromotive force signal into a square wave signal; and the processor is electrically connected with the waveform adjusting circuit to extract the frequency of the square wave signal and adjust the integration period of the analog-to-digital conversion according to the frequency of the square wave signal so as to enable the integration period to be integral multiple of the frequency of the square wave signal. The power frequency detection circuit and the power frequency interference elimination method are not directly electrically connected with a high-voltage alternating-current power supply, and have high safety; and a photoelectric coupler is not used, so that the aging failure phenomenon of the photoelectric coupler is avoided, and the photoelectric coupler is particularly suitable for low-power-consumption occasions.
Description
Technical Field
The invention relates to a method for detecting power frequency in the industry of instruments and meters, in particular to a power frequency interference elimination method for a power frequency detection circuit.
Background
The measuring instrument needs to collect analog quantity, when high-precision measurement is needed, the collection time needs to be integral multiple of power frequency, otherwise a test result is interfered by the power frequency to cause the result to be unstable, the technical requirement cannot be met, the power frequency needs to be detected, 220V and 50Hz alternating currents are used in China, and 60Hz alternating currents are used in other places in the world. The current method commonly used in the industry uses a photocoupler (short for photocoupler) to cooperate with a large number of other components for detection, as shown in fig. 1, but the method has certain defects:
(1) the high-voltage alternating current needs to be connected, so that certain dangerousness exists;
(2) the optical coupler is easy to age and lose efficacy, so that the frequency cannot be detected;
(3) certain power consumption is generated, and the low power consumption requirement is difficult to adapt.
The foregoing background is provided merely to clarify the technology to which this application relates and is not a representation of the prior art described above.
Disclosure of Invention
The invention aims to provide a power frequency interference elimination method for a power frequency detection circuit.
In order to solve the technical problem, the invention provides a method
The invention also provides a power frequency interference elimination method for the power frequency detection circuit, which comprises the following steps:
step S1, inducing an alternating magnetic field of alternating current to obtain an induced electromotive force signal;
step S2, converting the induced electromotive force signal into a square wave signal; and
and step S3, adjusting the integration period of the analog-to-digital conversion according to the frequency of the square wave signal, so that the integration period is an integral multiple of the frequency of the square wave signal, and eliminating power frequency interference.
In one embodiment, an alternating magnetic field of alternating current is induced through the spiral conductor; one end of the spiral lead is grounded through a current limiting resistor R1, and the other end of the spiral lead is connected with a waveform adjusting circuit; and the resistance value of the current limiting resistor is not less than 1M omega.
In one embodiment, the induced electromotive force signal is converted into a square wave signal through a waveform adjusting circuit; the waveform adjusting circuit comprises a low-pass filter and an in-phase proportional operation circuit; wherein the low pass filter comprises a resistor R4 and a ground circuit C1; one end of the resistor R4 is electrically connected with the other end of the spiral lead, and the other end of the resistor R4 is connected to the in-phase proportional operation circuit.
In one embodiment, the in-phase proportional operational circuit comprises an operational amplifier, and the in-phase end of the operational amplifier is electrically connected with the other end of the resistor R4; and a capacitor C2 is connected in parallel with the two ends of the feedback resistor R2 connected with the operational amplifier.
The power frequency detection circuit and the power frequency interference elimination method have the advantages that the power frequency detection circuit and the power frequency interference elimination method are not directly electrically connected with a high-voltage alternating-current power supply, and the safety is high; and a photoelectric coupler is not used, so that the aging failure phenomenon of the photoelectric coupler is avoided, and the photoelectric coupler is particularly suitable for low-power-consumption occasions.
Drawings
The invention is further illustrated with reference to the following figures and examples.
FIG. 1 is a circuit diagram of testing power frequency by an optocoupler in the background art;
FIG. 2 is a schematic block diagram of the power frequency detection circuit of the present invention;
FIG. 3 is a schematic circuit diagram of the power frequency detection circuit of the present invention;
FIG. 4 is a PCB printed circuit board diagram of the power frequency detection circuit of the present invention;
FIG. 5 is a waveform diagram of the output of the operational amplifier U1A of the present invention;
fig. 6 is a flowchart illustrating the steps of the power frequency interference cancellation method according to the present invention.
Detailed Description
The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic views illustrating only the basic structure of the present invention in a schematic manner, and thus show only the constitution related to the present invention.
As shown in fig. 2, this embodiment provides a power frequency detection circuit, including: an induction part for inducing an alternating magnetic field of alternating current to obtain an induced electromotive force signal; the waveform adjusting circuit is electrically connected with the induction part and used for converting the induced electromotive force signal into a square wave signal; and the processor is electrically connected with the waveform adjusting circuit to extract the frequency of the square wave signal and adjust the integration period of the analog-to-digital conversion according to the frequency of the square wave signal so as to enable the integration period to be integral multiple of the frequency of the square wave signal, eliminate power frequency interference and improve sampling precision.
The power frequency detection circuit is not directly electrically connected with a high-voltage alternating current power supply, so that the safety is high; and a photoelectric coupler is not used, so that the aging failure phenomenon of the photoelectric coupler is avoided, and the photoelectric coupler is particularly suitable for low-power-consumption occasions.
As shown in fig. 3, the sensing portion is a spiral wire, one end of which is grounded through a current limiting resistor R1, and the other end of which is connected to a waveform adjusting circuit; wherein the resistance value of the current limiting resistor is not less than 1M omega. Specifically, in this embodiment, the value of the current limiting resistor R1 is large, so as to prevent the induced charges from being rapidly lost, and 2M Ω may be used.
As shown in fig. 4, the spiral conductor is drawn on the printed circuit board in a square wave state.
The waveform adjusting circuit comprises a low-pass filter and an in-phase proportional operation circuit; wherein the low pass filter comprises a resistor R4 and a ground circuit C1; one end of the resistor R4 is electrically connected with the other end of the spiral lead, and the other end of the resistor R4 is connected to the in-phase proportional operation circuit. A low-pass filter can be used for filtering a part of high-frequency interference, and the induced electromotive force is amplified in a certain proportion through an in-phase proportion operation circuit.
The in-phase proportional operational circuit comprises an operational amplifier U1A, wherein the in-phase end of the operational amplifier U1A is electrically connected with the other end of the resistor R4; a capacitor C2 is connected in parallel with two ends of a feedback resistor R2 connected with the operational amplifier; the frequency characteristic of the operational amplifier U1A is improved by connecting the capacitor C2 and the feedback resistor R2 in parallel; the waveform of the output of the operational amplifier U1A is shown in FIG. 5.
As shown in fig. 6, this embodiment further provides a power frequency interference elimination method for a power frequency detection circuit, including the following steps:
step S1, inducing an alternating magnetic field of alternating current to obtain an induced electromotive force signal;
step S2, converting the induced electromotive force signal into a square wave signal; and
and step S3, adjusting the integration period of the analog-to-digital conversion according to the frequency of the square wave signal so that the integration period is an integral multiple of the frequency of the square wave signal, eliminating power frequency interference and improving sampling precision.
As shown in fig. 3, an alternating magnetic field of alternating current is induced by a spiral wire; one end of the spiral lead is grounded through a current limiting resistor R1, and the other end of the spiral lead is connected with a waveform adjusting circuit; and the resistance value of the current limiting resistor is not less than 1M omega. Specifically, in this embodiment, the value of the current limiting resistor R1 is large, so as to prevent the induced charges from being rapidly lost, and 2M Ω may be used.
Converting the induced electromotive force signal into a square wave signal through a waveform adjusting circuit; the waveform adjusting circuit comprises a low-pass filter and an in-phase proportional operation circuit; wherein the low pass filter comprises a resistor R4 and a ground circuit C1; one end of the resistor R4 is electrically connected with the other end of the spiral lead, and the other end of the resistor R4 is connected to the in-phase proportional operation circuit. A low-pass filter is adopted to filter out a part of high-frequency interference, and the induced electromotive force is amplified in a certain proportion through an in-phase proportion operation circuit.
The in-phase proportional operational circuit comprises an operational amplifier U1A, wherein the in-phase end of the operational amplifier U1A is electrically connected with the other end of the resistor R4; a capacitor C2 is connected in parallel with two ends of a feedback resistor R2 connected with the operational amplifier; the frequency characteristic of the operational amplifier U1A is improved by connecting the capacitor C2 and the feedback resistor R2 in parallel; the waveform of the output of the operational amplifier U1A is shown in FIG. 5.
In conclusion, the power frequency detection circuit and the power frequency interference elimination method are not directly electrically connected with a high-voltage alternating-current power supply, and are high in safety; and a photoelectric coupler is not used, so that the aging failure phenomenon of the photoelectric coupler is avoided, and the photoelectric coupler is particularly suitable for low-power-consumption occasions.
In light of the foregoing description of the preferred embodiment of the present invention, many modifications and variations will be apparent to those skilled in the art without departing from the spirit and scope of the invention. The technical scope of the present invention is not limited to the content of the specification, and must be determined according to the scope of the claims.
Claims (4)
1. A power frequency interference elimination method for a power frequency detection circuit is characterized by comprising the following steps:
step S1, inducing an alternating magnetic field of alternating current to obtain an induced electromotive force signal;
step S2, converting the induced electromotive force signal into a square wave signal; and
and step S3, adjusting the integration period of the analog-to-digital conversion according to the frequency of the square wave signal, so that the integration period is an integral multiple of the frequency of the square wave signal, and eliminating power frequency interference.
2. The power frequency interference cancellation method according to claim 1,
inducing an alternating magnetic field of alternating current through the spiral conductor; wherein
One end of the spiral lead is grounded through a current limiting resistor R1, and the other end of the spiral lead is connected with a waveform adjusting circuit; and
the resistance value of the current limiting resistor is not less than 1M omega.
3. The power frequency interference cancellation method according to claim 2,
converting the induced electromotive force signal into a square wave signal through a waveform adjusting circuit;
the waveform adjusting circuit comprises a low-pass filter and an in-phase proportional operation circuit; wherein
The low-pass filter comprises a resistor R4 and a ground circuit C1;
one end of the resistor R4 is electrically connected with the other end of the spiral lead, and the other end of the resistor R4 is connected to the in-phase proportional operation circuit.
4. The power frequency interference cancellation method according to claim 3,
the in-phase proportional operational circuit comprises an operational amplifier, and the in-phase end of the operational amplifier is electrically connected with the other end of the resistor R4; and
a capacitor C2 is connected in parallel with the two ends of the feedback resistor R2 connected with the operational amplifier.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111187166.5A CN113917229A (en) | 2021-10-12 | 2021-10-12 | Power frequency interference elimination method for power frequency detection circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111187166.5A CN113917229A (en) | 2021-10-12 | 2021-10-12 | Power frequency interference elimination method for power frequency detection circuit |
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| Publication Number | Publication Date |
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| CN113917229A true CN113917229A (en) | 2022-01-11 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN202111187166.5A Withdrawn CN113917229A (en) | 2021-10-12 | 2021-10-12 | Power frequency interference elimination method for power frequency detection circuit |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114401005A (en) * | 2022-03-25 | 2022-04-26 | 湖南恩智测控技术有限公司 | Power frequency interference elimination method and device |
-
2021
- 2021-10-12 CN CN202111187166.5A patent/CN113917229A/en not_active Withdrawn
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114401005A (en) * | 2022-03-25 | 2022-04-26 | 湖南恩智测控技术有限公司 | Power frequency interference elimination method and device |
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Application publication date: 20220111 |
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