CN201975773U - Over-voltage protection circuit of switching power-supply power-frequency filter capacitor - Google Patents
Over-voltage protection circuit of switching power-supply power-frequency filter capacitor Download PDFInfo
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- CN201975773U CN201975773U CN2010201554098U CN201020155409U CN201975773U CN 201975773 U CN201975773 U CN 201975773U CN 2010201554098 U CN2010201554098 U CN 2010201554098U CN 201020155409 U CN201020155409 U CN 201020155409U CN 201975773 U CN201975773 U CN 201975773U
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Abstract
The utility model discloses an over-voltage protection circuit of a switching power-supply power-frequency filter capacitor. The over-voltage protection circuit is connected with a main circuit of a switching power supply in series and comprises a bus-voltage detection circuit, an action valve-value circuit, an over-voltage control circuit and an executive circuit, wherein the bus-voltage detection circuit is used for detecting the voltage at a power-supply power-frequency filter capacitor end; the action valve-value circuit is used for detecting and comparing the voltage at the power-frequency filter capacitor end; and the over-voltage control circuit is used for controlling the executive circuit to execute the protection action according to the comparative result of the action valve-value circuit to protect the power-frequency filter capacitor from damage. By adopting the scheme of the over-voltage protection circuit, the over-voltage failure of the power-frequency filter capacitor caused by continuous over-high voltage of an electric network or surge voltage carried by the electric network can be effectively prevented, so that a switching power supply used by an electronic product can adapt to various severe power supply environments, the reliability of the switching power supply is improved, and the switching power supply is more competitive.
Description
Technical field the utility model relates to a kind of overvoltage crowbar, relates in particular to a kind of overvoltage crowbar of Switching Power Supply power frequency filter capacitor.
Background technology is used for convenience, and present many electronic products all are to utilize Switching Power Supply to insert on the power supply network to obtain power supply.There is multiple surge source on the power supply network, the situation that the power supply network voltage in perhaps a lot of areas is often unstable, exist sustained overvoltage, these situations can make the power frequency filter capacitor overvoltage in the Switching Power Supply, cause the overvoltage of power frequency filter capacitor to be lost efficacy, thereby cause the Switching Power Supply cisco unity malfunction, even can cause Switching Power Supply internal components and relevant device thereof to be damaged, serious also can cause accidents such as fire, blast.At present in order to make Switching Power Supply have input power supply overvoltage protection function, it generally is the device of an anti-surge in parallel between the live wire of input supply terminal and zero line, as piezo-resistance (Varistor, claim surge absorber again) or transient voltage inhibition diode TVS etc., but this type of anti-surge device price is more expensive, and surge energy that can only the weakened part, when surge voltage is higher, even adopt these anti-surge devices, the power frequency filter capacitor also may lose efficacy; And if the power transmission network sustained overvoltage, these devices will not have protective effect, thereby the power frequency filter capacitor can lose efficacy in the same old way and causes Switching Power Supply cisco unity malfunction or damage.
Summary of the invention the utility model purpose provides a kind of overvoltage crowbar of Switching Power Supply power frequency filter capacitor, and the power frequency filter capacitor in the protection switch power supply can not lose efficacy because of power supply network overtension or surge, improves the reliability of Switching Power Supply.
The utility model adopts following scheme to realize: the utility model is series in the Switching Power Supply main circuit; it comprises busbar voltage testing circuit, overvoltage control circuit, action threshold values circuit and the executive circuit of electric connection; described busbar voltage testing circuit detects the voltage of power frequency filter capacitor end; the voltage of the detected power frequency filter capacitor of the more described busbar voltage testing circuit of described action threshold values circuit end, described overvoltage control circuit is controlled described executive circuit execute protection action according to the comparative result of described action threshold values circuit.
Described busbar voltage testing circuit comprises four dividing potential drop sample resistance and filter capacitors that are connected in parallel with the dividing potential drop sample resistance that is connected the elementary earth terminal of described power supply of connecting successively that are connected between power frequency filter capacitor positive terminal and the elementary earth terminal of power supply.
Described overvoltage control circuit comprises the MOSFET pipe, the gate terminal of described MOSFET pipe connects a bleeder resistance, the drain electrode end of described MOSFET pipe connects a current-limiting resistance, and the drain electrode end of described MOSFET pipe is also connected on the switching tube gate terminal in the described executive circuit.
Described action threshold values circuit comprises that positive terminal is connected to the voltage-stabiliser tube of described MOSFET tube grid end, and the negative pole end of described voltage-stabiliser tube is connected in the busbar voltage testing circuit.
The drain electrode end of the switching tube in the described executive circuit is connected the negative pole end of power frequency filter capacitor, the source terminal of described switching tube is connected to the elementary earth terminal of power supply, the gate terminal of described switching tube is connected to the elementary earth terminal of power supply after connecting bleeder resistance again, the grid of described switching tube also is connected to the negative pole end of a diode, and the positive pole of this diode is connected to the error of Switching Power Supply main circuit control chip again and amplifies output.
The utility model utilizes busbar voltage testing circuit and action threshold values circuit to detect the voltage of comparison power frequency filter capacitor end in real time; when the overtension of power frequency filter capacitor end; overvoltage control circuit control executive circuit disconnects the connection of power frequency filter capacitor negative terminal reduces voltage; when power transmission network voltage recovers just often; executive circuit recloses power frequency filter capacitor negative terminal and connects; make the Switching Power Supply operate as normal, protection power frequency filter capacitor can not damage.
The beneficial effects of the utility model are: the utility model scheme can effectively prevent to continue the power frequency filter capacitor overvoltage inefficacy that surge voltage too high or that it carries causes because of power supply network voltage, make the Switching Power Supply of use for electronic products can adapt to various abominable power supply environment, improved the functional reliability of Switching Power Supply, made Switching Power Supply more competitive.
Description of drawings now is further elaborated the utility model in conjunction with the accompanying drawings:
Fig. 1 is circuit theory diagrams of the present utility model.
Embodiment as shown in Figure 1; the utility model is series in the Switching Power Supply main circuit 1; it comprises the busbar voltage testing circuit 21 of electric connection; action threshold values circuit 22; overvoltage control circuit 23 and executive circuit 24; busbar voltage testing circuit 21 detects the voltage of power frequency filter capacitor C907 end; action threshold values circuit 22 is the voltage of busbar voltage testing circuit 21 detected power frequency filter capacitor C907 ends relatively; overvoltage control circuit 23 is according to the comparative result control executive circuit 24 execute protections action of described action threshold values circuit 22, and protection power frequency filter capacitor C907 can not damage.
Busbar voltage testing circuit 21 comprises and is connected on four between power frequency filter capacitor C907 positive terminal and the elementary earth terminal of the power supply dividing potential drop sample resistance R863 that are connected in series successively, R860, R861, R862 and a filter capacitor C831 who is connected in parallel with dividing potential drop sample resistance R862.
Action threshold values circuit 22 comprises that positive terminal is connected to the voltage-stabiliser tube ZD801 of MOSFET pipe Q814 gate terminal, and the negative pole end of voltage-stabiliser tube ZD801 is connected to the common port of dividing potential drop sample resistance R862 and filter capacitor C831.
The drain electrode end of switching tube Q813 in the executive circuit 24 is connected the negative pole end of power frequency filter capacitor C907, the source terminal of switching tube Q813 is connected to the elementary earth terminal of power supply, the gate terminal of switching tube Q813 is connected to the elementary earth terminal of power supply after connecting bleeder resistance R858 again, the grid of switching tube Q813 also is connected to the negative pole end of a diode D804, and the positive pole of diode D804 is connected to the error of Switching Power Supply main circuit control chip IC901 again and amplifies output; When control chip IC901 selected LD7575PS for use, the positive pole of diode D804 was connected to the second control pin of this chip.
As shown in Figure 1, the alternating voltage on the power supply network is through the common mode inductance L901 in the Switching Power Supply main circuit 1, and L902 charges to power frequency filter capacitor C907 through rectifier bridge BD901 again.When the alternating voltage of power supply network is higher or power supply network when higher surge pulse is arranged, make the voltage at power frequency filter capacitor C907 two ends be elevated to withstand voltage specification easily above power frequency filter capacitor C907, will cause power frequency filter capacitor C907 to lose efficacy.
The utility model utilizes the R860 in the busbar voltage testing circuit, and R861, R862, R863 dividing potential drop sample resistance detect the voltage of power frequency filter capacitor C907 end; Dividing potential drop sample resistance R860, R861, R862, R863 make the overvoltage protection value at power frequency filter capacitor C907 two ends be fit to different application scenarios according to the corresponding resistance of the different choice of application scenario; Filter capacitor C831 and dividing potential drop sample resistance R862 parallel connection are used for preventing that protective circuit is subjected to short pulse such as thunderbolt to disturb misoperation because of power supply network, require filter capacitor C831 can select different appearance values for use according to the reaction sensitivity of protective circuit; When the voltage stabilizing value that surpasses voltage-stabiliser tube ZD801 when the voltage on the dividing potential drop sample resistance R862 is managed the threshold voltage sum of Q814 with MOSFET, MOSFET pipe Q814 conducting, grid voltage with switching tube Q813 drags down simultaneously, switching tube Q813 is ended, power frequency filter capacitor C907 negative terminal is disconnected, power supply network stops the charging to power frequency filter capacitor C907, and power frequency filter capacitor C907 terminal voltage no longer rises; Meanwhile, diode D804 drags down the second pin output voltage of Switching Power Supply control chip LD7575PS, the output of stopcock power supply control chip LD7575PS, and Switching Power Supply quits work.
When power transmission network voltage recovers just often, the detected voltage of dividing potential drop sample resistance R862 is lower than the voltage stabilizing value of voltage-stabiliser tube ZD801 and the threshold voltage sum of MOSFET pipe Q814, and MOSFET manages Q814 and ends; Capacitor C 911 positive terminal voltages are given Switching Power Supply control chip LD7575PS power supply, also give the gate charges of switching tube Q813 simultaneously through current-limiting resistance R859, when the grid voltage of switching tube Q813 reaches threshold voltage, switching tube Q813 conducting, power frequency filter capacitor C907 negative terminal is ground connection again, diode D804 ends the Switching Power Supply operate as normal simultaneously.
Claims (5)
1. the overvoltage crowbar of a Switching Power Supply power frequency filter capacitor; it is series in the Switching Power Supply main circuit; it is characterized in that: it comprises busbar voltage testing circuit, overvoltage control circuit, action threshold values circuit and the executive circuit of electric connection; described busbar voltage testing circuit detects the voltage of power frequency filter capacitor end; the voltage of the detected power frequency filter capacitor of the more described busbar voltage testing circuit of described action threshold values circuit end, described overvoltage control circuit is controlled described executive circuit execute protection action according to the comparative result of described action threshold values circuit.
2. the overvoltage crowbar of a kind of Switching Power Supply power frequency filter capacitor according to claim 1 is characterized in that: described busbar voltage testing circuit comprises four dividing potential drop sample resistance and filter capacitors that are connected in parallel with the dividing potential drop sample resistance that is connected the elementary earth terminal of described power supply of connecting successively that are connected between power frequency filter capacitor positive terminal and the elementary earth terminal of power supply.
3. the overvoltage crowbar of a kind of Switching Power Supply power frequency filter capacitor according to claim 1; it is characterized in that: described overvoltage control circuit comprises the MOSFET pipe; the gate terminal of described MOSFET pipe connects a bleeder resistance; the drain electrode end of described MOSFET pipe connects a current-limiting resistance, and the drain electrode end of described MOSFET pipe is also connected on the switching tube gate terminal in the described executive circuit.
4. according to the overvoltage crowbar of claim 1 or 3 described a kind of Switching Power Supply power frequency filter capacitors; it is characterized in that: described action threshold values circuit comprises that positive terminal is connected to the voltage-stabiliser tube of described MOSFET tube grid end, and the negative pole end of described voltage-stabiliser tube is connected in the busbar voltage testing circuit.
5. the overvoltage crowbar of a kind of Switching Power Supply power frequency filter capacitor according to claim 1; it is characterized in that: the drain electrode end of the switching tube in the described executive circuit is connected the negative pole end of power frequency filter capacitor; the source terminal of described switching tube is connected to the elementary earth terminal of power supply; the gate terminal of described switching tube is connected to the elementary earth terminal of power supply after connecting bleeder resistance again; the grid of described switching tube also is connected to the negative pole end of a diode, and the positive pole of this diode is connected to the error of Switching Power Supply main circuit control chip again and amplifies output.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2010201554098U CN201975773U (en) | 2010-04-09 | 2010-04-09 | Over-voltage protection circuit of switching power-supply power-frequency filter capacitor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2010201554098U CN201975773U (en) | 2010-04-09 | 2010-04-09 | Over-voltage protection circuit of switching power-supply power-frequency filter capacitor |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN201975773U true CN201975773U (en) | 2011-09-14 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN2010201554098U Expired - Fee Related CN201975773U (en) | 2010-04-09 | 2010-04-09 | Over-voltage protection circuit of switching power-supply power-frequency filter capacitor |
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| Country | Link |
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| CN (1) | CN201975773U (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103166199A (en) * | 2013-04-09 | 2013-06-19 | 许继集团有限公司 | Switching power supply and voltage protection method thereof |
| CN103197557A (en) * | 2013-03-27 | 2013-07-10 | 首都师范大学 | Real-time monitoring closed-loop control system and working method thereof |
| CN104518652A (en) * | 2014-12-26 | 2015-04-15 | 广东威创视讯科技股份有限公司 | Output voltage negative overshoot suppression device and method for DC-DC switching circuit |
| TWI704440B (en) * | 2019-10-29 | 2020-09-11 | 宏碁股份有限公司 | Power supply capable of reducing hold up time of output capacitor |
-
2010
- 2010-04-09 CN CN2010201554098U patent/CN201975773U/en not_active Expired - Fee Related
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103197557A (en) * | 2013-03-27 | 2013-07-10 | 首都师范大学 | Real-time monitoring closed-loop control system and working method thereof |
| CN103166199A (en) * | 2013-04-09 | 2013-06-19 | 许继集团有限公司 | Switching power supply and voltage protection method thereof |
| CN103166199B (en) * | 2013-04-09 | 2016-04-20 | 许继集团有限公司 | A kind of Switching Power Supply and voltage protection method thereof |
| CN104518652A (en) * | 2014-12-26 | 2015-04-15 | 广东威创视讯科技股份有限公司 | Output voltage negative overshoot suppression device and method for DC-DC switching circuit |
| TWI704440B (en) * | 2019-10-29 | 2020-09-11 | 宏碁股份有限公司 | Power supply capable of reducing hold up time of output capacitor |
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| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20110914 Termination date: 20150409 |
|
| EXPY | Termination of patent right or utility model |