CN212905128U - Zero-crossing detection circuit - Google Patents
Zero-crossing detection circuit Download PDFInfo
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- CN212905128U CN212905128U CN202020695473.9U CN202020695473U CN212905128U CN 212905128 U CN212905128 U CN 212905128U CN 202020695473 U CN202020695473 U CN 202020695473U CN 212905128 U CN212905128 U CN 212905128U
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Abstract
The utility model relates to a zero crossing detection circuit, including forceful electric power side part, light current side part and the opto-coupler module of setting between forceful electric power side part and light current side part; the method is characterized in that: the strong current side part comprises a current limiting module arranged in an alternating current loop to reduce the power consumption of the circuit and an optical coupling control module which is respectively and electrically connected with the current limiting module and the optical coupling module to control the on-off of the optical coupling module and reduce the conduction delay of the optical coupling module; the weak current side part comprises a direct current power supply connected with the optical coupling module and an output module respectively connected with the direct current power supply and the optical coupling module, and the output module can output an output signal which is synchronously switched between positive and negative according to the on-off state of the optical coupling module so as to perform zero-crossing detection. The detection circuit has low power consumption and small time delay.
Description
Technical Field
The utility model relates to an electric power product technology field especially relates to a zero cross detection circuit.
Background
The power line carrier communication product carries out signal transmission based on a power line, and the management unit can judge the phase position of a terminal product through zero-crossing information attached to the terminal product, so that the power line load, noise and user distribution are managed. In the prior art, zero-crossing information is mostly detected by sampling a zero-crossing signal of a power line voltage and then converting the zero-crossing signal into a weak current signal which can be processed by a low-voltage chip. However, the zero-crossing detection circuit in the prior art has high power consumption and large detection delay, and the detection accuracy is influenced.
SUMMERY OF THE UTILITY MODEL
In view of the above, an object of the present invention is to provide a zero-crossing detection circuit with low power consumption and small time delay.
In order to realize the purpose, the technical scheme of the utility model is that: a zero-crossing detection circuit comprises a strong current side part, a weak current side part and an optical coupling module arranged between the strong current side part and the weak current side part; the method is characterized in that:
the strong current side part comprises a current limiting module arranged in an alternating current loop to reduce the power consumption of the circuit and an optical coupling control module which is respectively and electrically connected with the current limiting module and the optical coupling module to control the on-off of the optical coupling module and reduce the conduction delay of the optical coupling module;
the weak current side part comprises a direct current power supply connected with the optical coupling module and an output module respectively connected with the direct current power supply and the optical coupling module, and the output module can output an output signal which is synchronously switched between positive and negative according to the on-off state of the optical coupling module so as to perform zero-crossing detection.
Further, the output signal of the output module is a voltage signal.
Furthermore, the zero-crossing detection circuit further comprises a rectifying module which is arranged between the current limiting module and the optical coupling control module and is respectively connected with the current limiting module and the optical coupling control module.
Furthermore, the current limiting module comprises a second resistor connected in series with the live wire and a fifth resistor connected in series with the zero wire.
Further, the resistance values of the second resistor and the fifth resistor are both 1M omega.
Further, the rectifier module comprises a first bidirectional diode arranged in the live wire and connected with the light emitting diode of the optical coupling module, and a second bidirectional diode arranged in the zero wire and electrically connected with the first bidirectional diode and the light emitting diode of the optical coupling module.
Further, the optocoupler control module comprises a first capacitor, a first NPN type triode, and a third bidirectional diode;
the first capacitor is respectively connected with the first bidirectional diode, the second bidirectional diode and the third bidirectional diode so as to charge when the live line voltage is positive half cycle and discharge to the optical coupling module when the live line voltage is negative half cycle to enable the optical coupling module to be conducted;
the base electrode of the first NPN type triode is electrically connected with the first bidirectional diode and the second bidirectional diode respectively, the collector electrode of the first NPN type triode is connected with the first bidirectional diode and the light emitting diode of the optocoupler module respectively, and the emitter electrode of the first NPN type triode is connected with the third bidirectional diode and the first capacitor respectively so as to cut off when the live line voltage is positive half cycle and enable the first capacitor to be charged and conduct when the live line voltage is negative half cycle and enable the first capacitor to be discharged to the optocoupler module.
Further, the optocoupler control module further includes a fourth resistor, a sixth resistor and a fifth capacitor, one end of the sixth resistor is connected to the base of the first NPN type triode, the other end of the sixth resistor is connected to one end of the fourth resistor, the other end of the fourth resistor is connected to the first bidirectional diode, and the fifth capacitor is connected between the emitter and the base of the first NPN type triode.
Further, the output module includes a second capacitor, a third resistor, a second NPN transistor, and a seventh resistor;
the third resistor is respectively connected with the direct current power supply and the second capacitor; the base electrode of the second NPN type triode is connected with the emitting electrode of the photosensitive triode of the optocoupler module, the collector electrode of the second NPN type triode is connected between the third resistor and the second capacitor, and the emitting electrode of the second NPN type triode is grounded;
the seventh resistor is arranged between the base electrode and the emitting electrode of the second NPN type triode; the other end of the second capacitor provides the output signal and is grounded through a fourth bidirectional diode.
Furthermore, a voltage dependent resistor is connected between the live wire and the zero line.
Compared with the prior art, the utility model has the advantages of:
the first capacitor is arranged for discharging to drive the optocoupler module to be conducted at the moment of zero crossing of voltage, and the charge-discharge duration of the second capacitor is prolonged by adjusting the third resistor and the seventh resistor, so that the positive and negative switching of the output signal can be synchronized with the on-off of the optocoupler module, the time delay of a zero switching signal detected on the weak current side is greatly reduced, and the accuracy of zero crossing detection is improved; meanwhile, the resistance values of the second resistor and the fifth resistor are set to be large enough, so that the power consumption of the circuit is greatly reduced.
Drawings
Fig. 1 is a schematic diagram of a zero-crossing detection circuit in the prior art.
Fig. 2 is a schematic diagram of a zero-crossing detection circuit according to the present application.
Detailed Description
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are exemplary only for the purpose of explaining the present invention, and should not be construed as limiting the present invention.
Fig. 1 is a schematic diagram of a zero-crossing detection circuit in the prior art, in which power consumption of the circuit mainly comes from strong current side current limiting resistors R28, R29, and R32, and power consumption calculation thereof refers to the following formula:
wherein Un is LN line voltage, Vd is rectifier diode forward voltage drop, Vop is optocoupler diode forward voltage drop, and R is a series resistance sum.
Through the formula, the power consumption of the zero-crossing detection circuit is about 0.24W (Un-220V), and the static power consumption of the whole meter without the module is about 0.6W, so that the power consumption of the zero-crossing detection circuit is excessive for the whole meter.
Meanwhile, in the zero-crossing detection circuit, as the light-emitting diode in the optical coupler needs certain conduction voltage for conduction, the light-emitting diode cannot be conducted at the zero-crossing moment when the live wire voltage is switched from the negative half cycle to the positive half cycle, and the light-emitting diode can be conducted only when the voltage rises to a certain value, so that the conduction moment of the optical coupler has certain time delay relative to the actual zero-crossing moment, and the accuracy of zero-crossing detection is reduced.
Therefore, the zero-crossing detection circuit is low in power consumption and small in time delay.
As shown in fig. 2, the zero-crossing detection circuit of the present application includes a strong current side portion, a weak current side portion, and an optical coupling module 1 disposed between the strong current side portion and the weak current side portion, where the strong current side portion includes a current limiting module 2 disposed in an ac circuit to reduce power consumption of the circuit, and an optical coupling control module 3 electrically connected to the current limiting module 2 and the optical coupling module 1 respectively to control on/off of the optical coupling module 1 and reduce conduction delay of the optical coupling module 1; correspondingly, the weak current side part includes a direct current power supply 4 connected to the optical coupling module 1, and an output module 5 respectively connected to the direct current power supply 4 and the optical coupling module 1, in this embodiment, the direct current power supply 4 is 3.3V, and the output module 5 can output an output signal that is synchronously switched between positive and negative according to the on-off state of the optical coupling module 1 so as to perform zero-crossing detection. In this application, the output signal of the output module 5 is a voltage signal.
Meanwhile, the zero-crossing detection circuit in the application further comprises a rectifying module 6 which is arranged between the current limiting module 2 and the optical coupling control module 3 and is respectively connected with the current limiting module 2 and the optical coupling control module 3. Specifically, the rectifying module 6 includes a first bidirectional diode VD1 disposed in the live line UL and connected to the light emitting diode of the optical coupling module 1, and a second bidirectional diode VD2 disposed in the neutral line UN and electrically connected to the first bidirectional diode VD1 and the light emitting diode of the optical coupling module 1.
In this embodiment, the current limiting module 2 includes a second resistor R2 connected in series to the live line UL and a fifth resistor R5 connected in series to the neutral line UN. In order to reduce the power consumption of the detection circuit, the resistances of the second resistor R2 and the fifth resistor R5 need to be set to be sufficiently large, and both values are 1M Ω in the present scheme.
With continued reference to fig. 2, the optocoupler control module 3 in the circuit includes a first capacitor C1, a first NPN-type triode V1, and a third bidirectional diode VD3, wherein the first capacitor C1 is connected to the first bidirectional diode VD1, the second bidirectional diode VD2, and the third bidirectional diode VD3, respectively, so as to charge the optocoupler module 1 when the voltage of the live line UL is a positive half cycle and discharge the voltage of the live line UN is a negative half cycle, so as to turn on the optocoupler module 1;
meanwhile, the base of the first NPN type triode V1 is electrically connected to the first bidirectional diode VD1 and the second bidirectional diode VD2, respectively, and the collector is connected to the first bidirectional diode VD1 and the light emitting diode of the optocoupler module 1, respectively, and the emitter is connected to the third bidirectional diode V3 and the first capacitor C1, respectively, so as to cut off when the UL voltage of the live wire is positive half cycle to charge the first capacitor C1, and turn on when the UL voltage of the live wire is negative half cycle to discharge the first capacitor C1 to the optocoupler module 1, so that the optocoupler module 1 is turned on.
The optocoupler control module 3 further includes a fourth resistor R4, a sixth resistor R6, and a fifth capacitor C5, wherein one end of the sixth resistor R6 is connected to the base of the first NPN transistor V1, the other end of the sixth resistor R6 is connected to one end of the fourth resistor R4, the other end of the fourth resistor R4 is connected to the first bidirectional diode VD1, and the fifth capacitor C5 is connected between the emitter and the base of the first NPN transistor V1.
The output module 5 in the present application includes a second capacitor C2, a third resistor R3, a second NPN transistor V2, and a seventh resistor R7; the third resistor R3 is respectively connected with the DC power supply 4 and the second capacitor C2; the base electrode of the second NPN type triode V2 is connected to the emitter electrode of the phototransistor of the optocoupler module 1, the collector electrode of the second NPN type triode V2 is connected between the third resistor R3 and the second capacitor C2, and the emitter electrode of the second NPN type triode V2 is grounded;
the seventh resistor R7 is disposed between the base and the emitter of the second NPN transistor V2; the other terminal of the second capacitor C2 provides the output signal and is connected to ground through a fourth bidirectional diode VD 4.
In order to prevent the overvoltage from damaging the circuit, a voltage dependent resistor RV1 is connected between the live line UL and the neutral line UN.
The working principle of the detection circuit is as follows:
for a circuit with a strong electric power side,
when UL is positive half cycle, a loop is formed by a live wire UL, a first bidirectional diode VD1, a first capacitor C1, a third bidirectional diode VD3, a second bidirectional diode VD2 and a zero line UN, at the moment, the first capacitor C1 is charged, and the optical coupling module 1 is not conducted;
when the UL changes from the positive half cycle to the negative half cycle, the first capacitor C1 provides a conduction voltage for the first NPN type triode V1 and the optocoupler module 1 to make the triodes instantly conducted to form a discharge loop, so that the problem of delay caused by the fact that the optocoupler module 1 needs to be conducted after a certain time after a zero crossing point due to non-conduction at the moment of voltage zero crossing in the prior art is solved, and when the fire wire UL is in the negative half cycle, the first capacitor C1 continuously discharges to keep the optocoupler module 1 in a continuous conduction state.
For the weak-current side circuit, the current,
when the optocoupler module 1 is not switched on, the direct current power supply 4, the third resistor R3, the second capacitor C2, the fourth bidirectional diode VD 4-ground form a loop, the second capacitor C2 is charged, and at this time, the voltage signal output by the output module 5 is about 0.6V;
when the optocoupler module 1 is switched on, the second NPN type triode V2 is switched on, the second capacitor C2 discharges, the second capacitor C2, the second NPN type triode V2, the fourth bidirectional diode VD4 and the second capacitor C2 form a loop, and meanwhile, the direct current power supply 4, the optocoupler module 1, the seventh resistor R7, the fourth bidirectional diode VD4 and the second capacitor C2 form a loop, and at this time, the voltage signal output by the output module 5 is about-0.6V;
the voltage signal output by the output module 5 is the zero-crossing detection signal, and the above analysis shows that the positive and negative switching of the voltage signal output by the output module 5 is performed synchronously with the on-off of the optocoupler module 1, that is, the detected zero-crossing point signal is synchronous with the actual zero-crossing point, thereby solving the problem of large delay in the prior art.
It should be noted that the charging and discharging time of the second capacitor C2 needs to be longer than half of the strong current period, otherwise, zero-cross sampling for the output signal will fail, and in order to achieve the purpose, the charging time of the second capacitor C2 is adjusted by adjusting the resistance value of R3, and the time for maintaining the output voltage signal at-0.6V is prolonged by adjusting the resistance value of R7, so as to ensure that the output signal of the output module 5 is synchronously switched between positive and negative according to the on and off of the optocoupler module 1, thereby achieving accurate zero-cross detection. It should be further noted that the selection of the R7 resistor is related to the opto-coupler module and the second NPN transistor V2, and needs to be adjusted according to actual conditions.
The power consumption of the circuit of the present application can be calculated by:
compared with the circuit power consumption in the prior art, the power consumption of the power supply is greatly reduced.
While embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that: various changes, modifications, substitutions and alterations can be made to the embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.
Claims (10)
1. A zero-crossing detection circuit comprises a strong current side part, a weak current side part and an optical coupling module (1) arranged between the strong current side part and the weak current side part; the method is characterized in that:
the strong current side part comprises a current limiting module (2) arranged in an alternating current loop to reduce the power consumption of the circuit, and an optical coupling control module (3) which is respectively and electrically connected with the current limiting module (2) and the optical coupling module (1) to control the on-off of the optical coupling module (1) and can reduce the conduction delay of the optical coupling module (1);
the weak current side part comprises a direct current power supply (4) connected with the optical coupling module (1) and an output module (5) respectively connected with the direct current power supply (4) and the optical coupling module (1), and the output module (5) can output an output signal which is synchronously switched between positive and negative according to the on-off state of the optical coupling module (1) so as to perform zero-crossing detection.
2. A zero-crossing detection circuit as claimed in claim 1, wherein:
the output signal of the output module (5) is a voltage signal.
3. A zero-crossing detection circuit as claimed in claim 1, wherein:
the zero-crossing detection circuit further comprises a rectifying module (6) which is arranged between the current limiting module (2) and the optical coupling control module (3) and is respectively connected with the current limiting module (2) and the optical coupling control module (3).
4. A zero-crossing detection circuit as claimed in claim 1, wherein:
the current limiting module (2) comprises a second resistor (R2) connected in series with the live wire (UL) and a fifth resistor (R5) connected in series with the neutral wire (UN).
5. A zero-crossing detection circuit as claimed in claim 4, wherein:
the resistance values of the second resistor (R2) and the fifth resistor (R5) are both 1M omega.
6. A zero-crossing detection circuit as claimed in claim 3, wherein:
the rectifying module (6) comprises a first bidirectional diode (VD1) arranged in a live wire (UL) and connected with a light emitting diode of the optical coupling module (1), and a second bidirectional diode (VD2) arranged in a neutral wire (UN) and electrically connected with the first bidirectional diode (VD1) and the light emitting diode of the optical coupling module (1).
7. A zero-crossing detection circuit as claimed in claim 6, wherein:
the optocoupler control module (3) comprises a first capacitor (C1), a first NPN type triode (V1) and a third bidirectional diode (VD 3);
the first capacitor (C1) is connected with the first bidirectional diode (VD1), the second bidirectional diode (VD2) and the third bidirectional diode (VD3) respectively so as to charge when the voltage of a live wire (UL) is positive half cycle and discharge to the optical coupling module (1) when the voltage of the live wire (UL) is negative half cycle to enable the optical coupling module (1) to be conducted;
the base electrode of the first NPN type triode (V1) is electrically connected with the first bidirectional diode (VD1) and the second bidirectional diode (VD2) respectively, the collector electrode of the first NPN type triode is connected with the first bidirectional diode (VD1) and the light emitting diode of the optical coupling module (1) respectively, and the emitter electrode of the first NPN type triode is connected with the third bidirectional diode (VD3) and the first capacitor (C1) respectively so as to cut off when the voltage of a live wire (UL) is positive half cycle to enable the first capacitor (C1) to be charged, and the voltage of the live wire (UL) is negative half cycle to be conducted to enable the first capacitor (C1) to be discharged to the optical coupling module (1).
8. A zero-crossing detection circuit as claimed in claim 7, wherein:
the optocoupler control module (3) further comprises a fourth resistor (R4), a sixth resistor (R6) and a fifth capacitor (C5), one end of the sixth resistor (R6) is connected with the base of the first NPN type triode (V1) while the other end of the sixth resistor (R6) is connected with one end of the fourth resistor (R4), the other end of the fourth resistor (R4) is connected with the first bidirectional diode (VD1), and the fifth capacitor (C5) is connected between the emitter and the base of the first NPN type triode (V1).
9. A zero-crossing detection circuit as claimed in claim 2, wherein:
the output module (5) comprises a second capacitor (C2), a third resistor (R3), a second NPN type triode (V2) and a seventh resistor (R7);
the third resistor (R3) is respectively connected with the direct current power supply (4) and the second capacitor (C2); the base electrode of the second NPN type triode (V2) is connected with the emitter electrode of the phototriode of the optical coupling module (1), the collector electrode of the second NPN type triode is connected between the third resistor (R3) and the second capacitor (C2), and the emitter electrode of the second NPN type triode is grounded;
the seventh resistor (R7) is arranged between the base electrode and the emitter electrode of the second NPN type triode (V2); the other end of the second capacitor (C2) provides the output signal and is grounded through a fourth bidirectional diode (VD 4).
10. A zero-crossing detection circuit as claimed in claim 4, wherein:
and a voltage dependent resistor (RV1) is also connected between the live wire (UL) and the zero wire (UN).
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| CN202020695473.9U CN212905128U (en) | 2020-04-29 | 2020-04-29 | Zero-crossing detection circuit |
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| CN202020695473.9U CN212905128U (en) | 2020-04-29 | 2020-04-29 | Zero-crossing detection circuit |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP4202449A1 (en) * | 2021-12-22 | 2023-06-28 | Hangzhou Lianxintong Semiconductor Co., Ltd. | Zero-crossing detection circuit |
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2020
- 2020-04-29 CN CN202020695473.9U patent/CN212905128U/en active Active
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| 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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