CN111193389A - Input surge impact prevention circuit and method - Google Patents
Input surge impact prevention circuit and method Download PDFInfo
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- CN111193389A CN111193389A CN202010080707.3A CN202010080707A CN111193389A CN 111193389 A CN111193389 A CN 111193389A CN 202010080707 A CN202010080707 A CN 202010080707A CN 111193389 A CN111193389 A CN 111193389A
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/32—Means for protecting converters other than automatic disconnection
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Abstract
The invention provides an input surge-impact-prevention circuit which comprises an input filter circuit, a slow start circuit, a rectification filter circuit, a control circuit and a sampling circuit, wherein the sampling circuit is connected between the input filter circuit and the control circuit, the control circuit is connected with the slow start circuit, and the control circuit comprises a first comparator U3A and a second comparator U3B. The invention provides a protection method of an input surge-proof impact circuit, which judges the sampling voltage by the mutual cooperation of a sampling circuit, a first comparator U3A and a second comparator U3B, can realize that when a switching power supply is in an abnormal working state (high-voltage or low-voltage input), the switching power supply is protected by a slow-start circuit, and when the switching power supply is in a normal working state, the consumption of a thermistor R4 in the slow-start circuit is stopped.
Description
Technical Field
The invention relates to the technical field of switching power supplies, in particular to an input surge-proof impact circuit.
Background
With the continuous development of power supply technology, the switching power supply has the advantages of small volume, high efficiency and the like, and is widely applied to the fields of computers, industrial control, communication, consumer electronics and the like. Meanwhile, with the increasingly wide application of the switching power supply, the stability and safety of the switching power supply become the problem of further attention and attention of people. The surge often appears when the power is started, abnormally used or struck by lightning, and in order to avoid the damage caused by the surge, the surge-proof circuit is often arranged when the power is designed.
In the prior art, the surge preventing circuit is usually used for reducing inrush current by connecting a thermistor in series at an input end, and reducing consumption of the thermistor during normal operation of the switching power supply by connecting a controllable short circuit in parallel at two ends of the thermistor, so that the reliability of the surge preventing circuit is further improved. However, how to better control the working time of the thermistor and further protect the switching power supply through the anti-surge circuit is a problem to be solved at present.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provides an input surge-proof circuit.
The technical problem to be solved by the invention is realized by adopting the following technical scheme:
the utility model provides an input surge protection rush circuit, is including input filter circuit, slow circuit and rectifier filter circuit, still including control circuit and sampling circuit, sampling circuit connects between input filter circuit and control circuit, control circuit links to each other with slow circuit, control circuit is including first comparator U3A and second comparator U3B.
Preferably, the output end of the input filter circuit is provided with a first capacitor CX 2.
Preferably, the sampling terminal of the sampling circuit is disposed at two ends of the first capacitor CX 2.
Preferably, the output terminal of the sampling circuit is connected to the non-inverting input terminal of the first comparator U3A and the inverting input terminal of the second comparator U3B, respectively.
Preferably, the output terminal of the sampling circuit is connected to the non-inverting input terminal of the first comparator U3A and the inverting input terminal of the second comparator U3B, respectively.
Preferably, the inverting input terminal of the first comparator U3A and the non-inverting input terminal of the second comparator U3B are connected to a reference voltage.
Preferably, the slow start circuit comprises a thermistor R4.
Preferably, the control circuit further comprises a switch tube V7 and a relay JK 1; the grid terminal of the switch tube V7 is connected with the output terminal of the first comparator U3A and the output terminal of the second comparator U3B, the relay JK1 comprises a trigger coil and a contact switch, the trigger coil is connected with the drain terminal of the switch tube V7, and the contact switch is connected with the thermistor R4 in parallel.
Preferably, the rectifying and filtering circuit includes a rectifying bridge D3 and a second capacitor CX 3.
The invention has the advantages and positive effects that: based on the cooperation between the sampling circuit and the control circuit, the first comparator U3A and the second comparator U3B are used for judging the double standards of the sampling voltage, so that the thermistor R4 is controlled more accurately and more stably, and the effect of protecting the switching power supply when the working state of the switching power supply is abnormal (low voltage or high voltage) is achieved.
Drawings
FIG. 1 is a schematic structural view of the present invention;
fig. 2 is a schematic diagram of the structure of the sampling circuit of the present invention.
Detailed Description
The embodiments of the invention will be described in further detail below with reference to the accompanying drawings:
as shown in the figure, the invention provides an input anti-surge impact circuit, which comprises an input filter circuit, a slow start circuit, a rectification filter circuit, a control circuit and a sampling circuit, wherein the sampling circuit is connected between the input filter circuit and the control circuit, the control circuit is connected with the slow start circuit, and the control circuit comprises a first comparator U3A and a second comparator U3B. It is added that the input end of the input filter circuit is connected with an alternating voltage.
Further, as shown in fig. 1 and fig. 2, a first capacitor CX2 is provided at the output end of the input filter circuit.
Further, as shown in fig. 1 and fig. 2, the sampling end of the sampling circuit is disposed at two ends of the first capacitor CX2, and the sampling circuit is configured to sample a voltage at two ends of the first capacitor CX 2.
Further, as shown in fig. 1 and fig. 2, the output terminal of the sampling circuit is connected to the non-inverting input terminal of the first comparator U3A and the inverting input terminal of the second comparator U3B, respectively.
Further, as shown in fig. 1, the inverting input terminal of the first comparator U3A and the non-inverting input terminal of the second comparator U3B are connected with a reference voltage, a first voltage dividing resistor R52 is connected in series between the inverting input terminal of the first comparator U3A and the reference voltage for dividing the voltage, and the inverting input terminal of the first comparator U3A is inputted with the first reference voltage; a second voltage dividing resistor R33 is connected in series between the non-inverting input terminal of the second comparator U3B and the reference voltage for voltage division, and a second reference voltage is input to the inverting input terminal of the second comparator U3B, and it is necessary to supplement that the first reference voltage value is smaller than the second reference voltage.
Specifically, in one embodiment of the present invention, the range of the input voltage required for the normal operation of the circuit is determined according to actual conditions, and the voltage values of the first reference voltage and the second reference voltage are changed by changing the resistance values of the first voltage-dividing resistor R52 and the second voltage-dividing resistor R33, so that the first reference voltage is the minimum input voltage required for the normal operation of the circuit, and the second reference voltage is the maximum input voltage required for the normal operation of the circuit.
Further, as shown in fig. 1, the slow-start circuit includes a thermistor R4, and the thermistor R4 is used for reducing the inrush current.
Further, as shown in fig. 1, the control circuit further includes a switching tube V7 and a relay JK 1; the grid terminal of the switch tube V7 is connected with the output terminal of the first comparator U3A and the output terminal of the second comparator U3B, the relay JK1 comprises a trigger coil and a contact switch, the trigger coil is connected with the drain terminal of the switch tube V7, and the contact switch is connected with the thermistor R4 in parallel.
Further, as shown in fig. 1, the rectifying and filtering circuit includes a rectifying bridge D3 and a second capacitor CX 3.
Specifically, in an embodiment of the present invention, when the input voltage is too low, that is, the voltage across the first capacitor CX2 is too low, the output terminal of the first comparator U3A outputs a low level, the output terminal of the second comparator U3B outputs a high level, the switching tube V7 is turned off, and the thermistor R4 is in an operating state to protect the circuit; when the input voltage is too high or the alternating current commercial power is suddenly added, because second electric capacity CX 3's instantaneous electric conductivity, first electric capacity CX2 both ends voltage is too high, at this moment, the output high level of first comparator U3A, the output low level of second comparator U3B, switch tube V7 ends, and thermistor R4 is in operating condition and protects the circuit. When the input voltage is normal, the output end of the first comparator U3A and the output end of the second comparator U3B both output high levels, the switch tube V7 is conducted, at the moment, the trigger coil of the relay JK1 connected with the switch tube V7 is conducted, the contact switch is closed, and the thermistor R4 is short-circuited and stops working.
The invention provides a protection method of an input surge-proof impact circuit, which comprises an input filter circuit, a slow start circuit, a rectification filter circuit, a control circuit and a sampling circuit, wherein the control circuit is connected with the slow start circuit, a thermistor is arranged in the slow start circuit, and a first comparator and a second comparator are arranged in the control circuit; the sampling circuit is used for sampling the voltage input to the filter circuit end, and simultaneously inputting the sampling voltage into the non-inverting input end of the first comparator and the inverting input end of the second comparator, the inverting input end of the first comparator and the non-inverting input end of the second comparator are provided with unequal reference voltages, when the first comparator and the second comparator output high levels, the slow-start circuit is short-circuited, the thermistor stops working and stops consuming, when the first comparator and the second comparator output low levels, the slow-start circuit works, and the thermistor starts protection on the circuit.
Furthermore, the input of the inverting input terminal of the first comparator is a first reference voltage, the input of the non-inverting input terminal of the second comparator is a second reference voltage, and the value of the first reference voltage is smaller than the value of the second reference voltage.
The specific working process of the input surge-proof impact circuit provided by the invention is as follows:
alternating current mains supply is input from an input end of the input filter circuit, and is output after sequentially passing through the slow start circuit and the rectification filter circuit, the sampling circuit is connected between the input filter circuit and the control circuit, the control circuit is connected with the slow start circuit, the sampling circuit samples the voltage at two ends of a first capacitor CX2 in the input filter circuit, and then the voltage is respectively compared with a first reference voltage and a second reference voltage through a first comparator U3A and a second comparator U3B, after comparison, the first comparator U3A and the second comparator U3B output level to a grid end of a switch tube V7 for driving, when the input voltage is too high or too low, the switch tube V7 is in a cut-off state, and the thermistor R4 works to protect the circuit; when the input voltage is normal, the switch tube V7 is in a conducting state, the thermistor R4 stops working, the temperature of the thermistor is reduced, the resistance value is increased, and the thermistor R4 is started again to work until the voltage fluctuates and deviates from a normal value. Based on the mutual cooperation of the modules, the switching power supply can be protected by the thermistor R4 when in an abnormal working state (high-voltage or low-voltage input), and the thermistor R4 stops being consumed when in a normal working state, so that the protection performance of the input surge-proof circuit is improved.
It should be emphasized that the embodiments described herein are illustrative rather than restrictive, and thus the present invention is not limited to the embodiments described in the detailed description, but other embodiments derived from the technical solutions of the present invention by those skilled in the art are also within the scope of the present invention.
Claims (10)
1. The utility model provides an input surge protection impact circuit, including input filter circuit, slow start circuit and rectification filter circuit, its characterized in that: the circuit is characterized by further comprising a control circuit and a sampling circuit, wherein the sampling circuit is connected between the input filter circuit and the control circuit, the control circuit is connected with the slow start circuit, and the control circuit comprises a first comparator U3A and a second comparator U3B.
2. The input surge protection circuit of claim 1, wherein: the output end of the input filter circuit is provided with a first capacitor CX 2.
3. The input surge protection circuit of claim 2, wherein: the sampling end of the sampling circuit is arranged at two ends of the first capacitor CX 2.
4. The input surge protection circuit of claim 1, wherein: the output end of the sampling circuit is respectively connected with the non-inverting input end of the first comparator U3A and the inverting input end of the second comparator U3B.
5. The input surge protection circuit of claim 1, wherein: the inverting input end of the first comparator U3A and the non-inverting input end of the second comparator U3B are connected with a reference voltage.
6. The input surge protection circuit of claim 1, wherein: the slow-start circuit comprises a thermistor R4.
7. The input surge protection circuit of claim 6, wherein: the control circuit also comprises a switch tube V7 and a relay JK 1; the grid terminal of the switch tube V7 is connected with the output terminal of the first comparator U3A and the output terminal of the second comparator U3B, the relay JK1 comprises a trigger coil and a contact switch, the trigger coil is connected with the drain terminal of the switch tube V7, and the contact switch is connected with the thermistor R4 in parallel.
8. The input surge protection circuit of claim 1, wherein: the rectifying and filtering circuit comprises a rectifying bridge D3 and a second capacitor CX 3.
9. A protection method of an input surge protection circuit comprises an input filter circuit, a slow start circuit and a rectification filter circuit, and is characterized in that: the circuit also comprises a control circuit and a sampling circuit, wherein the control circuit is connected with the slow start circuit, a thermistor is arranged in the slow start circuit, and a first comparator and a second comparator are arranged in the control circuit; the sampling circuit is used for sampling the voltage input to the filter circuit end, and simultaneously inputting the sampling voltage into the non-inverting input end of the first comparator and the inverting input end of the second comparator, the inverting input end of the first comparator and the non-inverting input end of the second comparator are provided with unequal reference voltages, when the first comparator and the second comparator output high levels, the slow-start circuit is short-circuited, the thermistor stops working and stops consuming, when the first comparator and the second comparator output low levels, the slow-start circuit works, and the thermistor starts protection on the circuit.
10. The method for protecting an input surge protection circuit according to claim 9, wherein: the input of the inverting input end of the first comparator is a first reference voltage, the input of the non-inverting input end of the second comparator is a second reference voltage, and the value of the first reference voltage is smaller than that of the second reference voltage.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010080707.3A CN111193389A (en) | 2020-02-05 | 2020-02-05 | Input surge impact prevention circuit and method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010080707.3A CN111193389A (en) | 2020-02-05 | 2020-02-05 | Input surge impact prevention circuit and method |
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| Publication Number | Publication Date |
|---|---|
| CN111193389A true CN111193389A (en) | 2020-05-22 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202010080707.3A Pending CN111193389A (en) | 2020-02-05 | 2020-02-05 | Input surge impact prevention circuit and method |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114825895A (en) * | 2022-06-27 | 2022-07-29 | 合肥博雷电气有限公司 | Input anti-surge slow starting circuit with overcurrent protection function |
-
2020
- 2020-02-05 CN CN202010080707.3A patent/CN111193389A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114825895A (en) * | 2022-06-27 | 2022-07-29 | 合肥博雷电气有限公司 | Input anti-surge slow starting circuit with overcurrent protection function |
| CN114825895B (en) * | 2022-06-27 | 2022-09-20 | 合肥博雷电气有限公司 | Input anti-surge slow starting circuit with overcurrent protection function |
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