CN212008738U - Current zero-crossing detection circuit - Google Patents
Current zero-crossing detection circuit Download PDFInfo
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- CN212008738U CN212008738U CN202020456529.5U CN202020456529U CN212008738U CN 212008738 U CN212008738 U CN 212008738U CN 202020456529 U CN202020456529 U CN 202020456529U CN 212008738 U CN212008738 U CN 212008738U
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Abstract
The utility model relates to a detection circuitry technical field specifically discloses a current zero crossing detection circuit, including sampling circuit, waveform conversion circuit and comparison circuit. The sampling circuit is connected with an alternating current signal input end and is used for converting the collected current signal into a voltage signal, and the voltage signal is a sine wave signal; the waveform conversion circuit is connected with the output end of the sampling circuit and is used for converting the sine wave signal into a sharp pulse signal; and the comparison circuit is connected with the output end of the waveform conversion circuit and is used for carrying out zero-crossing detection on the sharp pulse signal according to the reference comparison voltage and outputting a square wave signal. The application sets up the waveform conversion circuit and makes sine wave signal can convert sharp pulse signal into, helps improving the accuracy when follow-up zero crossing switches. Compared with the square wave signal output after the traditional isolation optocoupler rectification, the square wave signal output by the comparison unit has higher precision and stronger stability, and the reliability and the anti-interference capability of the current zero-crossing detection circuit are further ensured.
Description
Technical Field
The utility model relates to a detection circuitry technical field especially relates to a current zero crossing detection circuit.
Background
Zero-crossing detection refers to the detection made by the system when a zero is passed as the waveform transitions from a positive half cycle to a negative half cycle in an ac system.
The working principle of the existing zero-crossing detection circuit is that a high-voltage alternating-current signal is directly reduced to a low-voltage alternating-current signal through a transformer, strong and weak electricity is isolated through an isolation optocoupler, and then the low-voltage signal is converted into a square-wave signal after being rectified by the isolation optocoupler. However, the transformer in the above circuit is bulky, which results in a bulky whole circuit, is susceptible to interference, and has low detection accuracy.
SUMMERY OF THE UTILITY MODEL
Therefore, it is necessary to provide a current zero-crossing detection circuit for solving the problems of large size and low detection accuracy of the conventional zero-crossing detection circuit.
A current zero crossing detection circuit comprising:
the sampling circuit is connected with the alternating current signal input end and used for converting the collected current signal into a voltage signal, and the voltage signal is a sine wave signal;
the waveform conversion circuit is connected with the output end of the sampling circuit and is used for converting the sine wave signal into a sharp pulse signal;
and the comparison circuit is connected with the output end of the waveform conversion circuit and is used for carrying out zero-crossing detection on the sharp pulse signal according to the reference comparison voltage and outputting a square wave signal.
In one embodiment, the method further comprises the following steps:
and the current transformation circuit is connected between the alternating current signal input end and the sampling circuit and is used for reducing a large current signal at the alternating current signal input end into a small current signal.
In one embodiment, the method further comprises the following steps:
and the amplitude limiting circuit is connected between the sampling circuit and the waveform conversion circuit and is used for limiting the converted voltage signal.
In one embodiment, the method further comprises the following steps:
and the voltage division circuit is connected with the input end of the comparison circuit and is used for generating the reference comparison voltage.
In one embodiment, the method further comprises the following steps:
and the shaping circuit is connected with the output end of the comparison circuit and is used for shaping the square wave signal.
In one embodiment, the current transforming circuit comprises a current transformer, and the sampling circuit comprises a sampling resistor;
and a primary winding of the current transformer is connected with the alternating current signal input end, and a secondary winding of the current transformer is connected with the sampling resistor in parallel.
In one embodiment, the waveform conversion circuit is a differential circuit.
In one embodiment, the clipping circuit is connected in parallel with the sampling circuit and comprises two anti-phase parallel diodes.
In one embodiment, the comparison circuit comprises an operational amplifier, a non-inverting input terminal of the operational amplifier is connected with the output terminal of the waveform conversion circuit, and an inverting input terminal of the operational amplifier is connected with the reference comparison voltage.
In one embodiment, the signal amplifying circuit further comprises a resistor R4 and a resistor R7, a first end of the resistor R4 is connected to the output end of the waveform conversion circuit, a second end of the resistor R4 is connected to the non-inverting input end of the operational amplifier and the first end of the resistor R7, respectively, and a second end of the resistor R7 is connected to the output end of the operational amplifier.
The current zero-crossing detection circuit firstly samples from the alternating current signal input end through the sampling circuit, converts a current signal into a sine wave voltage signal, converts the sine wave signal into a sharp pulse signal through the waveform conversion circuit, and finally compares the sharp pulse signal with a reference comparison voltage through the comparison circuit, so that zero-crossing detection is realized, and a square wave signal is output. The transformer is not needed, and the volume of the whole circuit is reduced; in addition, the waveform conversion circuit is arranged, so that the sine wave signal can be converted into a sharp pulse signal, and the accuracy in subsequent zero-crossing switching is improved. Compared with the square wave signal output after the traditional isolation optocoupler rectification, the square wave signal output by the comparison unit has higher precision and stronger stability, and the reliability and the anti-interference capability of the current zero-crossing detection circuit are further ensured.
Drawings
Fig. 1 is a schematic structural diagram of an embodiment of a current zero-crossing detection circuit provided in an embodiment of the present application;
fig. 2 is a schematic structural diagram of another implementation of a current zero-crossing detection circuit provided in an embodiment of the present application;
fig. 3 is a schematic structural diagram of another implementation of a current zero-crossing detection circuit provided in an embodiment of the present application;
fig. 4 is a schematic structural diagram of yet another implementation of a current zero-crossing detection circuit provided in an embodiment of the present application;
fig. 5 is a specific example of a current zero-crossing detection circuit provided in an embodiment of the present application;
description of reference numerals:
10. a current transformation circuit; 20. a sampling circuit; 30. a clipping circuit; 40. a waveform conversion circuit; 50. a comparison circuit; 60. a shaping circuit; 70. a voltage dividing circuit; 80. a signal amplifying circuit.
Detailed Description
In order to facilitate understanding of the present invention, the present invention will be described more fully hereinafter with reference to the accompanying drawings. The preferred embodiments of the present invention are shown in the drawings. The invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
It will be understood that when an element is referred to as being "secured to" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. As used herein, the terms "vertical," "horizontal," "left," "right," "upper," "lower," "front," "rear," "circumferential," and the like are based on the orientation or positional relationship shown in the drawings and are intended to facilitate the description of the invention and to simplify the description, but do not indicate or imply that the device or element so referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus should not be construed as limiting the invention.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.
As mentioned in the background art, the conventional zero-crossing detection circuit generally reduces a high-voltage ac signal to a low-voltage ac signal through a transformer, isolates strong and weak electricity through an isolation optocoupler, and rectifies the low-voltage signal through the isolation optocoupler and converts the rectified signal into a square wave signal. The circuit has many defects, for example, the transformer has a larger volume, which causes the whole zero-crossing detection circuit to have a larger volume, poor anti-interference performance, low detection precision and the like.
In view of the above problem, an embodiment of the present application provides a current zero crossing detection circuit, which is used for detecting when a zero position passes when a waveform is converted from a positive half cycle to a negative half cycle in an ac system.
As shown in fig. 1, the current zero crossing detection circuit provided in the embodiment of the present application includes a sampling circuit 20, a waveform conversion circuit 40, and a comparison circuit 50. The sampling circuit 20 is connected to an alternating current signal input end, and is configured to convert an acquired current signal into a voltage signal, where the voltage signal is a sine wave signal; the waveform conversion circuit 40 is connected to the output end of the sampling circuit 20 and is used for converting the sine wave signal into a sharp pulse signal; the comparison circuit 50 is connected to the output end of the waveform conversion circuit 40, and is configured to perform zero-crossing detection on the spike signal according to the reference comparison voltage and output a square wave signal.
The current zero-crossing detection circuit firstly samples from an alternating current signal input end through the sampling circuit 20, converts a current signal into a sine wave voltage signal, converts the sine wave signal into a sharp pulse signal through the waveform conversion circuit 40, and finally compares the sharp pulse signal with a reference comparison voltage through the comparison circuit 50, so that zero-crossing detection is realized, and a square wave signal is output. The transformer is not needed, and the volume of the whole circuit is reduced; in addition, the waveform conversion circuit 40 is arranged to convert the sine wave signal into the sharp pulse signal, which is helpful to improve the accuracy of the subsequent zero-crossing switching. Compared with the square wave signal output after the traditional isolation optocoupler rectification, the square wave signal output by the comparison unit has higher precision and stronger stability, and the reliability and the anti-interference capability of the current zero-crossing detection circuit are further ensured.
Specifically, the ac signal input end is generally connected to the commercial power 220V, and referring to fig. 5, the sampling circuit 20 is a pure resistor circuit, and includes a sampling resistor R1, and two ends of the sampling resistor R1 are respectively connected to the ac signal input end, and are configured to convert a current signal at the ac signal input end into a voltage signal for subsequent detection. Wherein, the voltage signal is a sine wave signal. Of course, the sampling circuit 20 is not limited to the circuit constituted by the sampling resistor R1, and other circuit forms may be adopted as long as the sampling function can be realized.
As an alternative implementation manner, as shown in fig. 2, the current zero-crossing detection circuit provided in this embodiment further includes an inverter circuit 10, where the inverter circuit 10 is connected between the ac signal input end and the sampling circuit 20, and is used to reduce a large current signal input at the ac signal input end into a small current signal. Specifically, referring to fig. 5, the converter circuit 10 may include a current transformer T1, the current transformer T1 is an instrument for converting a large current into a small current according to the principle of electromagnetic induction, and includes a primary winding and a secondary winding, wherein the primary winding is connected to an ac signal input terminal, and the secondary winding is connected in parallel with the sampling circuit 20.
As an alternative embodiment, the waveform converting circuit 40 is a differentiating circuit, and specifically, referring to fig. 5, the differentiating circuit includes a capacitor C1 and a resistor R3, the resistor R3 is connected in parallel with the sampling circuit 20, and the capacitor C1 is connected in series with the output terminal of the sampling circuit 20. The sine wave signal output from the sampling circuit 20 is converted into a sharp pulse waveform signal by a differentiating circuit. The sine wave signal is converted into the sharp pulse waveform signal, so that the accuracy of subsequent zero-crossing detection switching is improved.
As an alternative implementation manner, as shown in fig. 3, the current zero-crossing detection circuit provided in this embodiment further includes a limiting circuit 30, and the limiting circuit 30 is connected between the sampling circuit 20 and the waveform converting circuit 40 and is used for limiting the converted voltage signal. Specifically, referring to fig. 5, the limiter circuit 30 in the present embodiment is preferably composed of two anti-parallel diodes, namely a diode D1 and a diode D2, and the diode D1 and the diode D2 are anti-parallel connected to the output end of the sampling circuit 20, and are used for performing limiter protection on the sine wave voltage signal output by the sampling circuit 20.
As an alternative embodiment, referring to fig. 5, the comparison circuit 50 includes an operational amplifier, a non-inverting input terminal of the operational amplifier U1 is connected to the output terminal of the waveform conversion circuit 40, and an inverting input terminal of the operational amplifier U1 is connected to the reference comparison voltage. The operational amplifier is an amplifying circuit capable of performing mathematical operations, and can perform operations such as addition and subtraction, calculus and the like as well as amplification by increasing or decreasing an analog input signal, and is widely applied and convenient to use. In this embodiment, the non-inverting input terminal of the operational amplifier U1 is configured to receive the spike waveform signal output by the waveform converting circuit 40, and the inverting input terminal is configured to access a reference comparison voltage, where the reference comparison voltage is a voltage for comparing with the spike waveform signal, and when the spike waveform signal satisfies the reference comparison voltage, the output square waveform of the output terminal of the operational amplifier U1 is inverted, thereby implementing zero crossing detection.
As an alternative embodiment, the reference comparison voltage is generated by a voltage divider circuit 70, as shown in fig. 4. Specifically, referring to fig. 5, the voltage divider circuit 70 includes a resistor R5 and a resistor R6, a first terminal of the resistor R6 is connected to VCC, a second terminal is connected to a first terminal of the resistor R5 and the inverting input terminal of the operational amplifier, and a second terminal of the resistor R5 is grounded. By selecting resistors R5 and R6 with appropriate resistance values, the reference comparison voltage required by the operational amplifier can be generated. The voltage divider circuit 70 formed by the resistor R5 and the resistor R6 has a simple structure, is easy to implement, and facilitates providing a reference comparison voltage.
As an alternative implementation, as shown in fig. 4, the current zero-crossing detection circuit provided in this embodiment further includes a signal amplification circuit 80, and referring to fig. 5, the signal amplification circuit 80 includes a resistor R4 and a resistor R7, a first end of the resistor R4 is connected to the output terminal of the waveform conversion circuit 40, a second end of the resistor R4 is connected to the non-inverting input terminal of the operational amplifier and the first end of the resistor R7, and a second end of the resistor R7 is connected to the output terminal of the operational amplifier. By providing the signal amplification circuit 80, the signal output can be amplified or reduced, and the output signal of the operational amplifier can be adjusted.
As an alternative implementation, as shown in fig. 4, the current zero crossing detection circuit provided in this embodiment further includes a shaping circuit 60. The shaping circuit 60 is connected to the output of the comparing circuit 50 for shaping the square wave signal. Referring to fig. 5, the shaping circuit 60 may be a schmitt trigger U2, and the schmitt trigger performs shaping processing such as removing glitches on the square wave signal output from the comparison circuit 50 to obtain a regular square wave signal.
A specific example of the current zero-cross detection circuit provided in the present embodiment is described below:
as shown in fig. 5, the current zero-crossing detection circuit includes a current converting circuit 10, a sampling circuit 20, a waveform converting circuit 40, a limiting circuit 30, a voltage dividing circuit 70, a comparing circuit 50, a signal amplifying circuit 80, and a shaping circuit 60.
The current transformer circuit 10 comprises a current transformer T1, the sampling circuit 20 comprises a sampling resistor R1, the waveform conversion circuit 40 comprises a capacitor C1 and a resistor R3, the amplitude limiting circuit 30 comprises diodes D1 and D2, the voltage dividing circuit 70 comprises resistors R5 and R6, the comparison circuit 50 comprises an operational amplifier U1, the signal amplification circuit 80 comprises a resistor R4 and a resistor R7, and the shaping circuit 60 is a Schmitt trigger U2.
A primary winding of the current transformer T1 is connected with an alternating current signal input end, a secondary winding is connected with a sampling resistor R1 in parallel, and the output end of the sampling resistor R1 is also connected with a resistor R2 in series; a first end of the resistor R2 is connected with a first end of the sampling resistor R1, a second end of the resistor R2 is respectively connected with an anode of the diode D1 and a cathode of the diode D2, a cathode of the diode D1 and an anode of the diode D2 are both connected with a second end of the sampling resistor R1, a cathode of the diode D2 is also connected with a first end of the capacitor C1, a second end of the capacitor C1 is connected with a first end of the resistor R3, and a second end of the resistor R3 is connected with an anode of the diode D2; the first end of the resistor R3 is also connected with the first end of the resistor R4, the second end of the resistor R4 is respectively connected with the non-inverting input end of the operational amplifier U1 and the first end of the resistor R7, and the second end of the resistor R7 is connected with the output end of the operational amplifier U1; the first end of the resistor R6 is connected with VCC, the second end of the resistor R5 and the inverting input end of the operational amplifier U1 are respectively connected with the first end of the resistor R5, the second end of the resistor R5 is grounded, and the first end of the resistor R5 is also connected with the second end of the resistor R3; the output end of the operational amplifier U1 is also connected with a Schmitt trigger U2.
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only represent some embodiments of the present invention, and the description thereof is specific and detailed, but not to be construed as limiting the scope of the present invention. It should be noted that, for those skilled in the art, without departing from the spirit of the present invention, several variations and modifications can be made, which are within the scope of the present invention. Therefore, the protection scope of the present invention should be subject to the appended claims.
Claims (10)
1. A current zero crossing detection circuit, comprising:
the sampling circuit is connected with the alternating current signal input end and used for converting the collected current signal into a voltage signal, and the voltage signal is a sine wave signal;
the waveform conversion circuit is connected with the output end of the sampling circuit and is used for converting the sine wave signal into a sharp pulse signal;
and the comparison circuit is connected with the output end of the waveform conversion circuit and is used for carrying out zero-crossing detection on the sharp pulse signal according to the reference comparison voltage and outputting a square wave signal.
2. A current zero crossing detection circuit as claimed in claim 1, further comprising:
and the current transformation circuit is connected between the alternating current signal input end and the sampling circuit and is used for reducing a large current signal at the alternating current signal input end into a small current signal.
3. A current zero crossing detection circuit as claimed in claim 1, further comprising:
and the amplitude limiting circuit is connected between the sampling circuit and the waveform conversion circuit and is used for limiting the converted voltage signal.
4. A current zero crossing detection circuit as claimed in claim 1, further comprising:
and the voltage division circuit is connected with the input end of the comparison circuit and is used for generating the reference comparison voltage.
5. A current zero crossing detection circuit as claimed in claim 1, further comprising:
and the shaping circuit is connected with the output end of the comparison circuit and is used for shaping the square wave signal.
6. A current zero-crossing detection circuit as claimed in claim 2, wherein the current transforming circuit comprises a current transformer, and the sampling circuit comprises a sampling resistor;
and a primary winding of the current transformer is connected with the alternating current signal input end, and a secondary winding of the current transformer is connected with the sampling resistor in parallel.
7. A current zero crossing detection circuit as claimed in claim 1 wherein the waveform conversion circuit is a differentiating circuit.
8. A current zero crossing detection circuit as claimed in claim 3, wherein the clipping circuit is connected in parallel with the sampling circuit and comprises two anti-phase parallel diodes.
9. A current zero-crossing detection circuit as claimed in claim 1, wherein the comparison circuit comprises an operational amplifier, a non-inverting input terminal of the operational amplifier is connected to the output terminal of the waveform conversion circuit, and an inverting input terminal of the operational amplifier is connected to the reference comparison voltage.
10. A current zero-crossing detection circuit as claimed in claim 9, further comprising a signal amplification circuit, wherein the signal amplification circuit comprises a resistor R4 and a resistor R7, a first terminal of the resistor R4 is connected to the output terminal of the waveform conversion circuit, a second terminal of the resistor R4 is connected to the non-inverting input terminal of the operational amplifier and a first terminal of the resistor R7, respectively, and a second terminal of the resistor R7 is connected to the output terminal of the operational amplifier.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202020456529.5U CN212008738U (en) | 2020-04-01 | 2020-04-01 | Current zero-crossing detection circuit |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202020456529.5U CN212008738U (en) | 2020-04-01 | 2020-04-01 | Current zero-crossing detection circuit |
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| CN212008738U true CN212008738U (en) | 2020-11-24 |
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| CN202020456529.5U Active CN212008738U (en) | 2020-04-01 | 2020-04-01 | Current zero-crossing detection circuit |
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