CN210572481U - Zero-crossing detection circuit - Google Patents
Zero-crossing detection circuit Download PDFInfo
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- CN210572481U CN210572481U CN201920729528.0U CN201920729528U CN210572481U CN 210572481 U CN210572481 U CN 210572481U CN 201920729528 U CN201920729528 U CN 201920729528U CN 210572481 U CN210572481 U CN 210572481U
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Abstract
The embodiment of the utility model discloses zero crossing detection circuit, this circuit includes: the input filtering module is used for accessing an alternating current input voltage, filtering the alternating current input voltage through a voltage limiting component and outputting the filtered voltage; the optical coupling conversion module is used for conducting work according to the filtered voltage, converting the alternating current voltage into direct current voltage and outputting the direct current voltage; the zero-crossing detection module is used for receiving the direct-current voltage output by the optocoupler conversion module and determining the frequency and the voltage inversion point of the alternating-current input voltage according to the level change point of the direct-current voltage; the input voltage detection module is used for sampling the direct current voltage output by the optical coupling conversion module and determining the voltage value of the alternating current input voltage according to the corresponding relation between the sampling result and the alternating current input voltage. Through the circuit, the voltage detection of the alternating current input voltage can be realized, and the lowest working voltage of the input end can be limited.
Description
Technical Field
The utility model relates to the field of electronic technology, especially, relate to a zero cross 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 zero-crossing detection circuit has wide application, can be used for judging the frequency, the voltage inversion point (namely the zero crossing point) and the like of a single-phase alternating-current power supply, and needs zero-crossing detection in many circuits, such as the application of a thyristor control system, an electric control system or a variable frequency control system of a PG stepless speed regulating motor and the like in the circuits.
The conventional zero-crossing detection circuit detects a zero-crossing signal of alternating voltage by using an optical coupler, the optical coupler works when alternating current is in a positive half cycle, the optical coupler does not work when the alternating current is in a negative half cycle, the output end of the optical coupler outputs a square wave waveform at the moment, and the frequency and the voltage inversion point of the alternating current are judged and judged by detecting the high and low levels of the square wave through an MCU (micro controller Unit). However, the conventional zero-crossing detection circuit usually detects only the zero-crossing signal, cannot detect and judge the voltage of the alternating-current input voltage, and is not high in detection accuracy.
SUMMERY OF THE UTILITY MODEL
The embodiment of the utility model provides a zero cross detection circuit can realize carrying out voltage detection to alternating current input voltage to can restrict the minimum operating voltage of input.
A zero-crossing detection circuit comprising:
the input filtering module comprises a voltage limiting component and is used for accessing an alternating current input voltage, filtering the alternating current input voltage through the voltage limiting component and outputting the filtered voltage;
the input end of the optical coupling conversion module is electrically connected with the input filtering module and used for conducting work according to the filtered voltage, converting alternating-current voltage into direct-current voltage and outputting the direct-current voltage;
the zero-crossing detection module is electrically connected with the first output end of the optical coupling conversion module and used for receiving the direct-current voltage output by the optical coupling conversion module and determining the frequency and the voltage inversion point of the alternating-current input voltage according to the level change point of the direct-current voltage;
and the input voltage detection module is electrically connected with the second output end of the optical coupling conversion module and is used for sampling the direct-current voltage output by the optical coupling conversion module and determining the voltage value of the alternating-current input voltage according to the corresponding relation between the voltage sampling result and the alternating-current input voltage.
Optionally, in one embodiment, the input filtering module includes a current limiting unit, a protection unit, and a voltage limiting unit, one end of the current limiting unit is electrically connected to the input end of the ac input voltage, and the other end of the current limiting unit is electrically connected to the first input end of the optocoupler conversion module; one end of the protection unit is electrically connected with the input end of the alternating-current input voltage, and the other end of the protection unit is electrically connected with the first input end of the optocoupler conversion module; one end of the voltage limiting unit is electrically connected with the input end of the alternating current input voltage, and the other end of the voltage limiting unit is electrically connected with the second input end of the optocoupler conversion module;
the current limiting unit is used for rectifying and limiting the alternating current input voltage, the protection unit is used for protecting the optical coupling conversion module, and the voltage limiting unit is used for limiting the working voltage of the optical coupling conversion module.
Optionally, in one embodiment, the current limiting unit includes a rectifier diode, a first resistor and a second resistor, an anode of the rectifier diode is electrically connected to a live wire end of an ac input voltage, a cathode of the rectifier diode is electrically connected to one end of the first resistor, the other end of the first resistor is electrically connected to one end of the second resistor, and the other end of the second resistor is electrically connected to one end of the protection unit and the first input end of the optocoupler conversion module, respectively.
Optionally, in one embodiment, the protection unit includes a voltage regulator tube and a third resistor, an anode of the voltage regulator tube and one end of the third resistor are electrically connected to a zero line end of the ac input voltage, respectively, and a cathode of the voltage regulator tube is electrically connected to the other end of the third resistor, the first input end of the optocoupler conversion module, and one end of the current limiting unit, respectively.
Optionally, in one embodiment, the voltage limiting unit includes a voltage regulator, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, and a first capacitor, an anode of the voltage regulator is electrically connected to a zero line end of the ac input voltage, and a cathode of the voltage regulator is electrically connected to the second input end of the optocoupler conversion module;
one end of the fourth resistor is electrically connected with the current limiting unit, the other end of the fourth resistor is electrically connected with one end of the fifth resistor, one end of the fifth resistor is electrically connected between the sixth resistor and the seventh resistor, one end of the sixth resistor is electrically connected with a zero line end of the alternating-current input voltage, the other end of the sixth resistor is electrically connected with one end of the seventh resistor, and the other end of the seventh resistor is electrically connected with a reference electrode of the voltage stabilizing source; one end of the first capacitor is electrically connected with the reference electrode of the voltage stabilizing source, and the other end of the first capacitor is electrically connected with the cathode of the voltage stabilizing source.
Optionally, in one embodiment, the optical coupler conversion module includes an optical coupler, a pin 1 and a pin 2 of the optical coupler are electrically connected to the input filter module, a pin 4 of the optical coupler is electrically connected to the zero-crossing detection module, a pin 3 of the optical coupler is electrically connected to the input voltage detection module, and the optical coupler is configured to convert the filtered voltage output by the input filter module into a dc voltage and output the dc voltage.
Optionally, in one embodiment, the zero-cross detection module includes a first power resistor and a micro control unit, one end of the first power resistor is electrically connected to a first output end of the optocoupler conversion module, and the other end of the first power resistor is electrically connected to an input end of the micro control unit.
Optionally, in one embodiment, the micro control unit includes an I/O port, the I/O port is electrically connected to one end of the first power resistor, and the micro control unit is configured to collect a dc voltage output by the optical coupler conversion module, determine a frequency of the ac input voltage according to a high-low level period of the dc voltage, and determine a voltage inversion point of the ac input voltage according to a high-level duty cycle of the dc voltage.
Optionally, in one embodiment, the input voltage detection module includes a second power resistor, a filter capacitor, and a micro control unit, one end of the second power resistor is electrically connected to the second output terminal of the optocoupler conversion module, the other end of the second power resistor is electrically connected to the input terminal of the micro control unit, and one end of the filter capacitor is electrically connected to one end of the second power resistor, and the other end of the filter capacitor is grounded.
Optionally, in one embodiment, the micro control unit includes an a/D sampling port, the a/D sampling port is electrically connected to one end of the second power resistor and one end of the filter capacitor, and the micro control unit is configured to convert the dc voltage output by the optical coupler conversion module into a digital voltage value through analog-to-digital conversion, and determine the voltage value of the ac input voltage according to a correspondence between the digital voltage value and the ac input voltage.
Implement the embodiment of the utility model provides a, will have following beneficial effect:
the zero-crossing detection circuit is connected with an alternating-current input voltage through an input filtering module, filters the alternating-current input voltage and outputs the filtered voltage; the optical coupling conversion module conducts and works according to the filtered voltage, converts alternating-current voltage into direct-current voltage and outputs the direct-current voltage; the zero-crossing detection module receives the direct-current voltage output by the optocoupler conversion module, and determines the frequency and the voltage inversion point of the alternating-current input voltage according to the level change point of the direct-current voltage; and the input voltage detection module is used for sampling the direct current voltage output by the optical coupling conversion module and determining the voltage value of the alternating current input voltage according to the corresponding relation between the sampling result and the alternating current input voltage. Through the circuit, the lowest working voltage of the input voltage can be limited, the detection part of the alternating current input voltage is added, the voltage detection of the alternating current input voltage can be realized while the zero-crossing detection is realized, the specific voltage value of the alternating current voltage can be detected, and the detection accuracy is improved.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.
Wherein:
FIG. 1 is a block diagram of a zero crossing detection circuit in one embodiment;
FIG. 2 is a block diagram of a zero-crossing detection circuit in another embodiment;
FIG. 3 is a circuit schematic of a zero crossing detection circuit in one embodiment;
fig. 4 is a diagram illustrating a relationship between an ac input voltage and an input voltage detection AD value according to an embodiment.
Detailed Description
In order to make the objects, technical solutions and advantages of the present application more apparent, the present application is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application.
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 application belongs. The terminology used herein in the description of the present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. It will be understood that, as used herein, the terms "first," "second," and the like may be used herein to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish one element from another. For example, a first application may be referred to as a second application, and similarly, the second application may be the first application, without departing from the scope of the present application. The first application and the second application are both applications, but they are not the same application.
As shown in fig. 1, which is a block diagram of a zero-crossing detection circuit in an embodiment, the zero-crossing detection circuit provided in this embodiment can detect a voltage of an ac input voltage and limit a lowest operating voltage of an input terminal. The zero-crossing detection circuit comprises an input filtering module 110, an optical coupling conversion module 120, a zero-crossing detection module 130 and an input voltage detection module 140, wherein the input filtering module 110 is electrically connected with the input end of the optical coupling conversion module 120, the zero-crossing detection module 130 is electrically connected with the first output end of the optical coupling conversion module 120, and the input voltage detection module 140 is electrically connected with the second output end of the optical coupling conversion module 120.
The input filtering module 110 includes a voltage limiting device, and is configured to access an ac input voltage, filter the ac input voltage through the voltage limiting device, and output the filtered voltage. Specifically, the ac input Voltage may be a commercial power, that is, a Voltage of 220V/50Hz, and the Voltage limiting component may be a Voltage regulator, and in some optional embodiments, may also be a Voltage dependent resistor, a Voltage regulator diode, a TVS (Transient Voltage Suppressor), or the like. The ac input voltage is filtered by the input filtering module 110, so that the minimum working voltage of the input voltage can be limited, the range of the input voltage can be conveniently limited in the testing process, and the appropriate input voltage can be conveniently screened.
Further, the optocoupler conversion module 120 switches on to work according to the filtered voltage, converts the ac voltage into a dc voltage, and outputs the dc voltage. Specifically, the optical coupler conversion module 120 includes an optical coupler, and when the optical coupler works, the optical coupler can convert an ac current at an input end into a dc current according to an optical coupler transmission ratio, where the optical coupler transmission ratio refers to a ratio between an output current and an input current of the optical coupler, and may also be referred to as a Current Transfer Ratio (CTR), an amplification factor or gain or a transmission slope of the optical coupler. The optocoupler transmission ratio can also be understood as the ratio of the secondary current to the primary current, i.e. the ratio of the maximum value of the current flowing on the primary side to the maximum value of the current flowing on the secondary side in the case of this primary current to the primary current. The optical coupler works in the positive half cycle of the alternating current input voltage, namely the optical coupler works when the alternating current voltage is positive; when the alternating current input voltage is in a negative half cycle, the optical coupler does not work, namely the optical coupler does not work when the alternating current voltage is negative; therefore, the waveform output by the output end of the optical coupler is square wave.
Further, the zero-cross detection module 130 receives the dc voltage output by the optical coupler conversion module 120, and determines the frequency and the voltage inversion point of the ac input voltage according to the level change point of the dc voltage. Specifically, since the waveform output by the optical coupling conversion module 120 is a square wave, the zero-cross detection module 130 judges the frequency and the voltage inversion point of the alternating current by collecting the waveform output by the output end of the optical coupling conversion module 120 and according to the high and low levels of the square wave.
Further, the input voltage detection module 140 samples the dc voltage output by the optocoupler conversion module 130, and determines the voltage value of the ac input voltage according to the corresponding relationship between the sampling result and the ac input voltage. Specifically, the dc voltage output by the optical coupling conversion module 130 may be sampled through an a/D sampling port of the micro control unit, an AD value of the dc voltage is obtained, and a voltage value of the ac input voltage is determined by analyzing a corresponding relationship between the AD value and the ac input voltage.
The zero-crossing detection circuit can limit the lowest working voltage of the input voltage, a detection part of the alternating current input voltage is added, the voltage detection of the alternating current input voltage can be realized while the zero-crossing detection is realized, the specific voltage value of the alternating current voltage can be detected, and the detection accuracy is improved.
In an embodiment, as shown in fig. 2, which is a block diagram of a zero-crossing detection circuit in another embodiment, the input filtering module 210 includes a current limiting unit 212, a protection unit 214, and a voltage limiting unit 216, and the current limiting unit 212, the protection unit 214, and the voltage limiting unit 216 are respectively connected between an input end of the ac input voltage and an input end of the opto-coupler conversion module 220. Specifically, one end of the current limiting unit 212 is electrically connected to an input end of an ac input voltage, and the other end of the current limiting unit 212 is electrically connected to a first input end of the optocoupler conversion module 220; one end of the protection unit 214 is electrically connected to an input end of an ac input voltage, and the other end of the protection unit 214 is electrically connected to a first input end of the optocoupler conversion module 220; one end of the voltage limiting unit 216 is electrically connected to an input end of the ac input voltage, and the other end of the voltage limiting unit 216 is electrically connected to a second input end of the opto-coupler conversion module 220. The current limiting unit 210 rectifies and limits the ac input voltage through a current limiting device, the protection unit 220 protects the optocoupler in the optocoupler conversion module 220 through a voltage stabilizing device, and the voltage limiting unit 230 limits the ac input voltage through a voltage limiting device and is configured to limit the operating voltage of the optocoupler conversion module 220.
In one embodiment, the current limiting unit includes a rectifying diode, a first resistor and a second resistor, an anode of the rectifying diode is electrically connected to a live wire end of an ac input voltage, a cathode of the rectifying diode is electrically connected to one end of the first resistor, the other end of the first resistor is electrically connected to one end of the second resistor, and the other end of the second resistor is electrically connected to one end of the protection unit and the first input end of the optocoupler conversion module, respectively.
Specifically, as shown in fig. 3, which is a circuit schematic diagram of the zero-cross detection circuit in an embodiment, the current limiting unit includes a diode D305, a resistor R332, and a resistor R333, the diode D305, the resistor R332, and the resistor R333 are sequentially connected in series, an anode of the diode D305 is electrically connected to a live line L2 of the ac input voltage, and one end of the resistor R333 is electrically connected to a pin No. 1 at an input end of the optocoupler U307. The diode D305 is a rectifier diode for filtering out a negative half cycle portion of the ac input current, and the resistors R332 and R333 are current limiting resistors, it is understood that the number of the current limiting resistors may be smaller or larger in some embodiments, for example, 1 or more than 2, and this embodiment is not limited thereto.
In one embodiment, the protection unit includes a voltage regulator tube and a third resistor, the voltage regulator tube and the third resistor are connected in parallel, an anode of the voltage regulator tube and one end of the third resistor are electrically connected to a zero line end of the ac input voltage, respectively, and a cathode of the voltage regulator tube is electrically connected to the other end of the third resistor, the first input end of the optocoupler conversion module, and one end of the current limiting unit, respectively.
Specifically, please refer to fig. 3 again, the protection unit includes a voltage regulator ZD301 and a resistor R337, the voltage regulator ZD301 and the resistor R337 are connected in parallel, an anode of the voltage regulator ZD301 and one end of the resistor R337 are electrically connected to a zero line N2 end of the ac input voltage, and a cathode of the voltage regulator ZD301 and the other end of the resistor R337 are electrically connected to the pin No. 1 input end of the optocoupler U307. The voltage-regulator tube ZD301 and the resistor R337 are reverse protection of the optocoupler U307.
In one embodiment, the voltage limiting unit comprises a voltage stabilizing source, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor and a first capacitor, wherein the anode of the voltage stabilizing source is electrically connected with the zero line end of the alternating current input voltage, and the cathode of the voltage stabilizing source is electrically connected with the input end of the optocoupler conversion module; one end of the fourth resistor is electrically connected with the current limiting unit, the fourth resistor and the fifth resistor are connected in series, one end of the fifth resistor is electrically connected between the sixth resistor and the seventh resistor, one end of the sixth resistor is electrically connected with a zero line end of the alternating-current input voltage, the sixth resistor and the seventh resistor are connected in series, and one end of the seventh resistor is electrically connected with a reference electrode of the voltage stabilizing source; one end of the first capacitor is electrically connected with the reference electrode of the voltage stabilizing source, and the other end of the first capacitor is electrically connected with the cathode of the voltage stabilizing source.
Specifically, with reference to fig. 3, the voltage limiting unit includes a resistor R338, a resistor R340, a resistor R345, a resistor R346, a capacitor C322, and a voltage regulator U309, one end of the resistor R338 is electrically connected to the negative electrode of the diode D305, the resistor R340 is connected in series with the resistor R338, one end of the resistor R345 is electrically connected to the end of the zero line N2 of the ac input voltage, the resistor R346 is connected in series with the resistor R345, one end of the resistor R340 is connected between the resistor R346 and the resistor R345, the anode of the voltage regulator U309 is electrically connected to the end of the zero line N2 of the ac input voltage, the cathode is electrically connected to the No. 2 pin at the input end of the opto-coupler U307, the reference electrode is electrically connected to one end of the resistor R346, one end of the capacitor C322 is electrically connected to the reference electrode of the voltage.
The reference voltage of the voltage regulator source U309 is Vref, for example, the voltage regulator source U309 may adopt TL431, the TL431 is a controllable precision voltage regulator source, the internal reference voltage of the TL431 is 2.5V, and the TL431 operates when the Vref voltage is higher than 2.5V. In this embodiment, Vref is U/(R338+ R340+ R345) R345, where Vref is the reference voltage of TL431, U is the input voltage, R338 is the resistance of resistor R338, R340 is the resistance of resistor R340, and R345 is the resistance of resistor R345; that is, the lowest operating voltage of the input voltage is: (R338+ R340+ R345) × R345 × Vref, the minimum working voltage of the input voltage in this embodiment is: (R338+ R340+ R345) × R345 × 2.5V, and the lowest operating voltage of the input voltage can be set by selecting the resistances of the resistor R338, the resistor R340, and the resistor R345. Capacitor C322 is used to spike absorb the regulator U309.
In one embodiment, the optical coupler conversion module comprises an optical coupler, and the optical coupler is used for converting positive half cycle voltage of the alternating current input voltage into output. Specifically, please continue to refer to fig. 3, pin 1 and pin 2 of the optocoupler U307 are electrically connected to the input filter module, pin 4 of the optocoupler is electrically connected to the zero-crossing detection module, pin 3 of the optocoupler is electrically connected to the input voltage detection module, and the optocoupler is configured to convert the filtered voltage output by the input filter module into a dc voltage and output the dc voltage.
In one embodiment, the zero-crossing detection module comprises a first power resistor and a micro control unit, wherein one end of the first power resistor is electrically connected with a first output end of the optocoupler conversion module, and the other end of the first power resistor is electrically connected with an input end of the micro control unit. Further, the micro control unit comprises an I/O port, and the I/O port is electrically connected with one end of the first power resistor.
Specifically, please refer to fig. 3, the zero-cross detection module includes a resistor R341, a resistor R334, a transistor Q201, and VCC, one end of the resistor R334 is electrically connected to the pin No. 4 of the output terminal of the optocoupler U307 and VCC, the other end of the resistor R334 is electrically connected to an I/O interface of an MCU (micro controller Unit), one end of the resistor R341 is electrically connected to the pin No. 3 of the output terminal of the optocoupler U307, the other end of the resistor R341 is electrically connected to the gate of the transistor Q201, the drain of the transistor Q201 is electrically connected to the I/O interface of the MCU, and the source of the transistor Q201 is grounded. When the alternating current input voltage is larger than the set input voltage minimum value, the optocoupler U307 starts to work to output square waves, and the I/O interface of the MCU can detect the frequency and the voltage inversion point of the alternating current input voltage. The MCU can collect the direct current voltage output by the optocoupler conversion module, determine the frequency of the alternating current input voltage according to the high-low level period of the direct current voltage, and determine the voltage inversion point of the alternating current input voltage according to the high-level duty ratio of the direct current voltage.
In one embodiment, the input voltage detection module includes a second power resistor, a filter capacitor and a micro control unit, one end of the second power resistor is electrically connected to the second output terminal of the optocoupler conversion module, the other end of the second power resistor is electrically connected to the input terminal of the micro control unit, and one end of the filter capacitor is electrically connected to one end of the second power resistor, and the other end of the filter capacitor is grounded. Further, the MCU comprises an A/D sampling port, and the A/D sampling port is electrically connected with one end of the second power resistor and one end of the filter capacitor.
Specifically, referring to fig. 3, the input voltage detecting module includes a resistor R341, a resistor R347, a resistor R339, a resistor R342, and a resistor R348, the transistor Q202, the capacitor C323 and the capacitor C324, the resistor R341 is connected in series with the resistor R347, one end of the resistor R341 is electrically connected with the pin No. 3 of the output end of the optocoupler U307, the gate of the transistor Q202 is connected between the resistor R341 and the resistor R347, the source of the transistor Q202 is connected with one end of the resistor R347, one end of the resistor R339 is electrically connected with the pin No. 4 of the output end of the optocoupler U307, the other end of the resistor R339 is electrically connected with the drain of the transistor Q202, the resistor R342 is connected in series with the resistor R348, one end of the resistor R342 is electrically connected with the drain of the transistor Q202, one end of the resistor R348 is electrically connected with the A/D sampling interface of the MCU, one end of the capacitor C323 is connected between the resistor R342 and the resistor.
In one embodiment, the MCU is configured to convert a dc voltage output by the optical coupling conversion module into a digital voltage value through analog-to-digital conversion, and determine a voltage value of the ac input voltage according to a correspondence between the digital voltage value and the ac input voltage.
TABLE 1 correspondence table of AC input voltage and input voltage detection AD value
Specifically, as shown in table 1, the correspondence table between the ac input voltage and the input voltage detection AD value is obtained according to the experimental test record, where the input voltage detection AD value is a digital voltage value, that is, the correspondence table between the digital voltage value and the ac input voltage, and the input voltage detection AD values corresponding to different ac input voltage values are different. In this embodiment, the minimum operating voltage is defined as 160V, and when the ac input voltage is 158V, the MCU cannot obtain the input voltage detection AD value. Further, fig. 4 is a diagram illustrating a correspondence relationship between the ac input voltage and the input voltage detection AD value in an embodiment, and it can be seen from fig. 4 that the input voltage detection AD value gradually decreases as the ac input voltage gradually increases. According to the corresponding relation between the alternating-current input voltage and the input voltage detection AD value, the voltage value of the alternating-current input voltage can be determined through the input voltage detection AD value obtained by the MCU.
The zero-crossing detection circuit is connected with an alternating-current input voltage through an input filtering module, filters the alternating-current input voltage and outputs the filtered voltage; the optical coupling conversion module conducts and works according to the filtered voltage, converts alternating-current voltage into direct-current voltage and outputs the direct-current voltage; the zero-crossing detection module receives the direct-current voltage output by the optocoupler conversion module, and determines the frequency and the voltage inversion point of the alternating-current input voltage according to the level change point of the direct-current voltage; and the input voltage detection module is used for sampling the direct current voltage output by the optical coupling conversion module and determining the voltage value of the alternating current input voltage according to the corresponding relation between the sampling result and the alternating current input voltage. Through the circuit, the lowest working voltage of the input voltage can be limited, the detection part of the alternating current input voltage is added, the voltage detection of the alternating current input voltage can be realized while the zero-crossing detection is realized, the specific voltage value of the alternating current voltage can be detected, and the detection accuracy is improved.
The above-mentioned embodiments only express several embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present application. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the concept of the present application, which falls within the scope of protection of the present application. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (10)
1. A zero-crossing detection circuit, comprising:
the input filtering module comprises a voltage limiting component and is used for accessing an alternating current input voltage, filtering the alternating current input voltage through the voltage limiting component and outputting the filtered voltage;
the input end of the optical coupling conversion module is electrically connected with the input filtering module and used for conducting work according to the filtered voltage, converting alternating-current voltage into direct-current voltage and outputting the direct-current voltage;
the zero-crossing detection module is electrically connected with the first output end of the optical coupling conversion module and used for receiving the direct-current voltage output by the optical coupling conversion module and determining the frequency and the voltage inversion point of the alternating-current input voltage according to the level change point of the direct-current voltage;
and the input voltage detection module is electrically connected with the second output end of the optical coupling conversion module and is used for sampling the direct-current voltage output by the optical coupling conversion module and determining the voltage value of the alternating-current input voltage according to the corresponding relation between the voltage sampling result and the alternating-current input voltage.
2. A zero-crossing detection circuit as claimed in claim 1, wherein the input filtering module comprises a current limiting unit, a protection unit and a voltage limiting unit, one end of the current limiting unit is electrically connected with the input end of the ac input voltage, and the other end of the current limiting unit is electrically connected with the first input end of the optocoupler conversion module; one end of the protection unit is electrically connected with the input end of the alternating-current input voltage, and the other end of the protection unit is electrically connected with the first input end of the optocoupler conversion module; one end of the voltage limiting unit is electrically connected with the input end of the alternating current input voltage, and the other end of the voltage limiting unit is electrically connected with the second input end of the optocoupler conversion module;
the current limiting unit is used for rectifying and limiting the alternating current input voltage, the protection unit is used for protecting the optocoupler conversion module, and the voltage limiting unit is used for limiting the alternating current input voltage.
3. A zero-crossing detection circuit as claimed in claim 2, wherein the current limiting unit comprises a rectifier diode, a first resistor and a second resistor, an anode of the rectifier diode is electrically connected to a live line end of the ac input voltage, a cathode of the rectifier diode is electrically connected to one end of the first resistor, the other end of the first resistor is electrically connected to one end of the second resistor, and the other end of the second resistor is electrically connected to one end of the protection unit and the first input end of the optocoupler conversion module, respectively.
4. A zero-crossing detection circuit as claimed in claim 2, wherein the protection unit comprises a voltage regulator tube and a third resistor, an anode of the voltage regulator tube and one end of the third resistor are electrically connected to a zero line end of the ac input voltage, respectively, and a cathode of the voltage regulator tube is electrically connected to the other end of the third resistor, the first input end of the optocoupler conversion module and one end of the current limiting unit, respectively.
5. A zero-crossing detection circuit as claimed in claim 2, wherein the voltage limiting unit comprises a voltage regulator, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor and a first capacitor, wherein an anode of the voltage regulator is electrically connected with a zero line end of the ac input voltage, and a cathode of the voltage regulator is electrically connected with a second input end of the opto-coupler conversion module;
one end of the fourth resistor is electrically connected with the current limiting unit, the other end of the fourth resistor is electrically connected with one end of the fifth resistor, one end of the fifth resistor is electrically connected between the sixth resistor and the seventh resistor, one end of the sixth resistor is electrically connected with a zero line end of the alternating-current input voltage, the other end of the sixth resistor is electrically connected with one end of the seventh resistor, and the other end of the seventh resistor is electrically connected with a reference electrode of the voltage stabilizing source; one end of the first capacitor is electrically connected with the reference electrode of the voltage stabilizing source, and the other end of the first capacitor is electrically connected with the cathode of the voltage stabilizing source.
6. A zero-crossing detection circuit according to claim 1, wherein the optical coupler conversion module comprises an optical coupler, a pin 1 and a pin 2 of the optical coupler are electrically connected to the input filter module, a pin 4 of the optical coupler is electrically connected to the zero-crossing detection module, a pin 3 of the optical coupler is electrically connected to the input voltage detection module, and the optical coupler is configured to convert the filtered voltage output by the input filter module into a dc voltage and output the dc voltage.
7. A zero-crossing detection circuit as claimed in claim 1, wherein the zero-crossing detection module comprises a first power resistor and a micro control unit, one end of the first power resistor is electrically connected to a first output end of the optocoupler conversion module, and the other end of the first power resistor is electrically connected to an input end of the micro control unit.
8. A zero-crossing detection circuit as claimed in claim 7, wherein the micro control unit includes an I/O port, the I/O port is electrically connected to one end of the first power resistor, and the micro control unit is configured to collect the DC voltage output by the optical coupler conversion module, determine the frequency of the AC input voltage according to the high-low level period of the DC voltage, and determine the voltage inversion point of the AC input voltage according to the high-level duty cycle of the DC voltage.
9. A zero-crossing detection circuit as claimed in claim 1, wherein the input voltage detection module comprises a second power resistor, a filter capacitor and a micro control unit, one end of the second power resistor is electrically connected to the second output terminal of the optical coupling conversion module, the other end of the second power resistor is electrically connected to the input terminal of the micro control unit, and one end of the filter capacitor is electrically connected to one end of the second power resistor, and the other end of the filter capacitor is grounded.
10. A zero-crossing detection circuit as claimed in claim 9, wherein the micro control unit includes an a/D sampling port, the a/D sampling port is electrically connected to one end of the second power resistor and one end of the filter capacitor, and the micro control unit is configured to convert the dc voltage output by the optical coupling conversion module into a digital voltage value through analog-to-digital conversion, and determine the voltage value of the ac input voltage according to the corresponding relationship between the digital voltage value and the ac input voltage.
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| CN201920729528.0U CN210572481U (en) | 2019-05-17 | 2019-05-17 | Zero-crossing detection circuit |
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| CN201920729528.0U CN210572481U (en) | 2019-05-17 | 2019-05-17 | Zero-crossing detection circuit |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112383327A (en) * | 2020-11-18 | 2021-02-19 | 上海蜂电网络科技有限公司 | Carrier wave AC/DC communication method |
| CN113791342A (en) * | 2021-09-14 | 2021-12-14 | 公牛集团股份有限公司 | Switching device and electrical appliance |
| CN113934242A (en) * | 2021-10-08 | 2022-01-14 | 冠州科技(广州)有限公司 | Heating control device and heating system |
| EP4202449A1 (en) * | 2021-12-22 | 2023-06-28 | Hangzhou Lianxintong Semiconductor Co., Ltd. | Zero-crossing detection circuit |
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2019
- 2019-05-17 CN CN201920729528.0U patent/CN210572481U/en active Active
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112383327A (en) * | 2020-11-18 | 2021-02-19 | 上海蜂电网络科技有限公司 | Carrier wave AC/DC communication method |
| CN112383327B (en) * | 2020-11-18 | 2021-06-08 | 上海蜂电网络科技有限公司 | Carrier wave AC/DC communication method |
| CN113791342A (en) * | 2021-09-14 | 2021-12-14 | 公牛集团股份有限公司 | Switching device and electrical appliance |
| CN113791342B (en) * | 2021-09-14 | 2024-03-01 | 公牛集团股份有限公司 | Switching device and electric appliance |
| CN113934242A (en) * | 2021-10-08 | 2022-01-14 | 冠州科技(广州)有限公司 | Heating control device and heating system |
| CN113934242B (en) * | 2021-10-08 | 2023-08-18 | 冠州科技(广州)有限公司 | Heating control device and heating system |
| EP4202449A1 (en) * | 2021-12-22 | 2023-06-28 | Hangzhou Lianxintong Semiconductor Co., Ltd. | Zero-crossing detection circuit |
| US11835553B2 (en) | 2021-12-22 | 2023-12-05 | Hangzhou Lianxintong Semiconductor Co., Ltd. | Zero-crossing detection circuit |
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