CN115407118B - AC zero-crossing detection circuit of isolated output square wave - Google Patents
AC zero-crossing detection circuit of isolated output square wave Download PDFInfo
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- CN115407118B CN115407118B CN202211074365.XA CN202211074365A CN115407118B CN 115407118 B CN115407118 B CN 115407118B CN 202211074365 A CN202211074365 A CN 202211074365A CN 115407118 B CN115407118 B CN 115407118B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/175—Indicating the instants of passage of current or voltage through a given value, e.g. passage through zero
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R15/00—Details of measuring arrangements of the types provided for in groups G01R17/00 - G01R29/00, G01R33/00 - G01R33/26 or G01R35/00
- G01R15/14—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks
- G01R15/24—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using light-modulating devices
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Abstract
The invention discloses an AC zero-crossing detection circuit for an isolated output square wave, wherein pins 3 and 1 of a comparator U1 are respectively connected with a live wire and a zero wire at an input end through resistors R8 and R9, a resistor R14 is connected between pins 3 and 2 of the comparator U1, a resistor R11 is connected between pins 1 and 2 of the comparator U1, a diode D5 is connected on pins 1 and 3 of the comparator U1 in parallel, a diode D6 is connected on D5 in parallel, pin 5 of the comparator U1 is connected with a power supply through a resistor R10, pin 4 of the comparator U1 is connected with a primary side PC1A of an optical coupler PC1 through a resistor R17, a primary side PC1A of the optical coupler PC1 is connected with a pin 2 of the comparator U2, a secondary side PC1B of the optical coupler PC1 is grounded through a resistor R22, and a junction of the secondary side PC1B of the optical coupler PC1 and the resistor R22 is connected with an AC zero-crossing signal line. The invention has the advantages that: the AC zero-crossing detection is completed by using a single group of comparators and optocouplers, the occupied space is small, and the device is convenient to select.
Description
Technical Field
The invention relates to the technical field of circuits, in particular to an AC zero-crossing detection circuit for an isolated output square wave.
Background
The prior art basically uses a series of resistors plus 4 sets of comparators to effect the transfer of the primary AC zero crossing information to the secondary, which has the following drawbacks:
1. in order to meet the primary and secondary safety requirements, at least 12 patch resistors with 1206 and high resistance values are used as sampling resistors, and enough space is reserved on the periphery of the resistors due to the safety requirements, so that the method occupies very space;
2. although the mode accords with the safety rule, the mode is non-isolated, the leakage current of the primary and secondary stages is increased, the leakage current of the Y capacitor is occupied, and only the Y capacitor with smaller capacitance value can be selected during the design of the power supply.
Disclosure of Invention
The invention aims to solve the technical problem and provides an AC zero-crossing detection circuit for completing AC zero-crossing detection by utilizing a single comparator and an optocoupler.
In order to solve the technical problems, the technical scheme provided by the invention is as follows: the utility model provides an AC zero crossing detection circuitry of isolation type output square wave, includes comparator U1 and opto-coupler PC1, comparator U1's No. 3 pin and No. 1 pin are connected with live wire and zero line of input respectively through resistance R8 and R9, there is resistance R14 between comparator U1's No. 3 and No. 2 pin, there is resistance R11 between comparator U1's No. 1 and No. 2 pin, the parallel connection has diode D5 on comparator U1's No. 1 and No. 3 pin, the parallel connection has diode D6 on diode D5, comparator U1's No. 5 pin is connected with the power through resistance R10, comparator U1's No. 4 pin is connected with opto-coupler PC 1's primary side PC1A through resistance R17, opto-coupler PC 1's primary side PC1A is connected with comparator U2's No. 2 pin, opto-coupler PC 1's secondary side PC1B is connected with voltage output through resistance R21, opto-coupler PC 1's secondary side PC1B is connected with the electric resistance R22 through resistance R22, the parallel connection has resistance R23 on the electric-coupler PC 1's the parallel connection with the electric resistance R23.
Further, the optocoupler isolates the primary and secondary.
Further, the comparator U1 collects an AC signal.
Compared with the prior art, the invention has the advantages that: the primary side of the power adapter is used for supplying power to a group of comparators, the conversion of an AC signal to a DC signal is completed at the primary side, then the DC signal is transmitted to the secondary side by using an optical coupler, the voltage amplitude which can be acquired by the MCU is separated by using the secondary power supply of the adapter, and the primary secondary side is isolated by using the optical coupler, so that the space utilization rate is improved; the electric leakage of the system is reduced by using the optocoupler to isolate the primary stage; part of parts of the flyback circuit are utilized, the number of parts is reduced, and the cost is slightly reduced.
Drawings
Fig. 1 is a circuit schematic of the present invention.
Fig. 2 is a circuit diagram of the present invention in actual use.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings.
With reference to fig. 1-2, pins 3 and 1 of the comparator U1 are respectively connected with a live wire and a zero line of an input end through resistors R8 and R9, a resistor R14 is connected between pins 3 and 2 of the comparator U1, a resistor R11 is connected between pins 1 and 2 of the comparator U1, the resistor R14 is connected with R11 in series, the resistor R11 is connected with R9 in series, a diode D5 is connected with pins 1 and 3 of the comparator U1 in parallel, a diode D6 is connected with the diode D5 in parallel, pin 5 of the comparator U1 is connected with a power supply through a resistor R10, pin 4 of the comparator U1 is connected with a primary side PC1A of the optocoupler PC1 through a resistor R17, the primary side PC1A of the optocoupler PC1 is connected with pin 2 of the comparator U2, the primary side PC1A signal is grounded, a secondary side PC1B of the optocoupler PC1 is connected with a voltage output resistor R21 and a resistor R22, and the secondary side PC 22 is connected with a zero line of the resistor R23 in parallel, and the secondary side PC1 is connected with a resistor R22.
AC zero crossing detection is accomplished using comparator U1 and optocoupler PC 1. The input current is limited by resistors R8 and R9, the voltage is divided by resistors R11 and R14, and the voltage input to the comparator is limited by diodes D5 and D6. The comparator is powered by Vcc of the power supply through resistor R10. The output signal of the comparator is transmitted to the light emitting side of the optocoupler through a resistor R17, and the receiving side of the optocoupler divides the output voltage through resistors R21 and R22 to obtain proper AC zero crossing signal voltage. Resistor R23 and capacitor C10 may help fine tune the AC zero crossing signal voltage.
The input voltage will reverse at the zero crossing of the AC, the output voltage will be a 0V, high voltage (slightly lower than Vcc) square wave. When the light emitting side of the optocoupler inputs high voltage, the secondary receiving side is conducted, and the AC is used for collecting and dividing the voltage to a high-voltage signal, for example, 3V. When the light emitting side of the optocoupler inputs 0V, the secondary receiving side is closed, the AC collection is connected with low potential, and 0V is output. The duty of the 0V,3V square wave is 50%, corresponding to the upper half wave and the lower half wave of the sine.
The invention and its embodiments have been described in a non-limiting manner, and the actual construction is not limited to the embodiments of the invention as shown in the drawings. In summary, if one of ordinary skill in the art is informed by this disclosure, a structural manner and an embodiment similar to the technical solution should not be creatively devised without departing from the gist of the present invention.
Claims (3)
1. The utility model provides an AC zero crossing detection circuit of isolation type output square wave, includes comparator U1 and opto-coupler PC1, its characterized in that: the pins 3 and 1 of the comparator U1 are respectively connected with a live wire and a zero wire of an input end through resistors R8 and R9, a resistor R14 is connected between the pins 3 and 2 of the comparator U1, a resistor R11 is connected between the pins 1 and 2 of the comparator U1, a diode D5 is connected on the pins 1 and 3 of the comparator U1 in parallel, a diode D6 is connected on the diode D5 in parallel, the pin 5 of the comparator U1 is connected with a power supply through a resistor R10, the pin No. 4 of comparator U1 is connected with the primary side PC1A of opto-coupler PC1 through resistance R17, the primary side PC1A of opto-coupler PC1 is connected with the pin No. 2 of comparator U2, the secondary side PC1B of opto-coupler PC1 is connected with voltage output through resistance R21, the secondary side PC1B of opto-coupler PC1 is grounded through resistance R22, the resistance R22 is connected with a resistance R23 in parallel, the resistance R23 is connected with a capacitor C10 in parallel, and the junction of the secondary side PC1B of opto-coupler PC1 and resistance R22 is connected with an AC zero crossing signal line.
2. An AC zero crossing detection circuit for an isolated output square wave as defined in claim 1, wherein: the optocoupler isolates the primary and secondary.
3. An AC zero crossing detection circuit for an isolated output square wave as defined in claim 1, wherein: the comparator U1 collects an AC signal.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211074365.XA CN115407118B (en) | 2022-09-03 | 2022-09-03 | AC zero-crossing detection circuit of isolated output square wave |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211074365.XA CN115407118B (en) | 2022-09-03 | 2022-09-03 | AC zero-crossing detection circuit of isolated output square wave |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN115407118A CN115407118A (en) | 2022-11-29 |
| CN115407118B true CN115407118B (en) | 2023-06-02 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN202211074365.XA Active CN115407118B (en) | 2022-09-03 | 2022-09-03 | AC zero-crossing detection circuit of isolated output square wave |
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Family Cites Families (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102411082A (en) * | 2011-07-29 | 2012-04-11 | 深圳和而泰智能控制股份有限公司 | Energy-saving zero-crossing detection circuit and device |
| CN202256476U (en) * | 2011-09-30 | 2012-05-30 | 海信科龙电器股份有限公司 | Zero passage signal detection circuit |
| US9046555B2 (en) * | 2011-12-19 | 2015-06-02 | Tyco Safety Products Canada Ltd. | Latching over-current protection circuit and method |
| CN202583311U (en) * | 2012-04-13 | 2012-12-05 | Tcl空调器(中山)有限公司 | Alternating current zero-crossing detection circuit |
| CN204065223U (en) * | 2014-08-01 | 2014-12-31 | 库顿电子科技（厦门）有限公司 | The zero cross detection circuit that a kind of optocoupler drives |
| CN204694767U (en) * | 2015-06-12 | 2015-10-07 | 深圳市优逸电子科技有限公司 | A kind of Width funtion low-power consumption two-way zero-crossing testing circuit |
| CN105182229B (en) * | 2015-09-22 | 2018-06-29 | 郑贵林 | The dynamic measurement of power switch actuation time and ac zero-crossing point accuracy control method and application |
| CN207528810U (en) * | 2017-12-18 | 2018-06-22 | 厦门华联电子股份有限公司 | A kind of zero-crossing detecting circuit with low power consumption |
| CN208060617U (en) * | 2018-02-09 | 2018-11-06 | 四川爱创科技有限公司 | AC zero passage detections export the circuit of square wave |
| CN210894489U (en) * | 2019-09-30 | 2020-06-30 | 杜照涢 | Zero-crossing detection circuit |
| CN110954739A (en) * | 2019-11-19 | 2020-04-03 | 上海沪臻智能科技有限公司 | AC voltage zero-crossing trigger detection circuit |
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2022
- 2022-09-03 CN CN202211074365.XA patent/CN115407118B/en active Active
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| CN115407118A (en) | 2022-11-29 |
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