CN106451350A - Switching power supply protection circuit and device and switching power supply - Google Patents
Switching power supply protection circuit and device and switching power supply Download PDFInfo
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- CN106451350A CN106451350A CN201510473275.1A CN201510473275A CN106451350A CN 106451350 A CN106451350 A CN 106451350A CN 201510473275 A CN201510473275 A CN 201510473275A CN 106451350 A CN106451350 A CN 106451350A
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Abstract
The invention discloses a switching power supply protection circuit. The circuit comprises an overvoltage protection element, a first overcurrent protection element, and a second overcurrent protection element. The overvoltage protection element is connected in parallel between a live line and a zero line of a power input end. The first overcurrent protection element and the overvoltage protection element are connected in parallel. The second overcurrent protection element is in series connection with the overvoltage protection element, and the connection is cut off if the current of the overvoltage protection element increases and the temperature exceeds a preset threshold value. The invention also correspondingly provides a switching power supply protection device and a switching power supply. According to the technical scheme of the invention, the switching power supply circuit can be protected more effectively.
Description
Technical field
The invention belongs to field of circuit technology is and in particular to a kind of protective circuit of switch power source, protection device and Switching Power Supply.
Background technology
Switching power circuit is operated on off state due to its power transistor, has obtained widely applying in Power convert field.For a certain concrete application occasion, the output voltage of usual switching power circuit is a fixing DC voltage, but its input voltage might have certain change.In Switching Power Supply input, power voltage surge typically can be produced.So-called surge, is also surging it is simply that transient overvoltage beyond normal voltage, the high current that the high voltage as " unrestrained " for the short time referring generally to occur in circuit causes.
In the circuit of prior art, as shown in figure 1, the method being adopted for suppression surge voltage is, by common MOV（Metal Oxide Varistor, metal-oxide varistor）It is attempted by the L of power input（Live wire）、N （Zero line）Between, when surge enters power supply, surge voltage is absorbed by varistor MOV, thus reducing impact.
But, the processing method of prior art, while absorbing surge voltage, also can give MOV（Bring certain damage.After the n times work going round and beginning again, add the life problems of MOV itself, the internal current of MOV can constantly aggravate so as to internal constantly heat up, and the phenomenon such as finally may set off an explosion, catch fire.
Therefore, existing switching power circuit guard method imperfection is it would be desirable to there be safer guard method.
Content of the invention
The technical problem to be solved is to provide a kind of protective circuit of switch power source, protection device and Switching Power Supply, and energy more effectively protection switch power circuit is it is ensured that user uses safety.
The technical scheme that the present invention provides is as follows：
The present invention provides a kind of protective circuit of switch power source：
Described protection circuit includes overvoltage protection element, the first over-current protecting element and the second over-current protecting element；Wherein,
Described overvoltage protection element is connected in parallel between the live wire of power input and zero line；
Described first over-current protecting element is in parallel with described overvoltage protection element；
Described second over-current protecting element is connected with described overvoltage protection element, disconnects when the electric current of described overvoltage protection element increases and temperature exceedes given threshold.
Preferably：Described overvoltage protection element is varistor, and described first over-current protecting element is first fuse, and described second over-current protecting element is second fuse；
Described varistor is connected in parallel between the live wire of power input and zero line；
Described first fuse is in parallel with described varistor；
Described second fuse is connected with described varistor, disconnects when the electric current of described varistor increases and temperature exceedes given threshold.
Preferably：Described second fuse is entangled using sleeve pipe with described varistor.
Preferably：Described protection circuit also includes rectification circuit, is used for converting alternating current to Rectified alternating current；
One end of described first fuse is connected with one end of described rectification circuit, and the other end of described first fuse is connected with one end of described varistor；
The other end of described varistor is connected with the other end of described rectification circuit.
Preferably：Described second fuse is high fusing-off temperature fuse, and described varistor is high-energy metal-oxide varistor.
Preferably：Described sleeve pipe is heat-shrinkable T bush.
The present invention also provides a kind of Switching Power Supply protection device, comprises above-mentioned protective circuit of switch power source.
The present invention also provides a kind of Switching Power Supply, comprises above-mentioned protective circuit of switch power source.
Preferably：Described Switching Power Supply also includes the first filter circuit, charging capacitor, PWM controller, metal-oxide-semiconductor, transformator, the second rectification circuit, the second filter circuit；
Described first filter circuit, after the alternating current of described power input is changed into Rectified alternating current by the rectification circuit in described protective circuit of switch power source, described Rectified alternating current is transformed into smooth direct current electricity；
Described charging capacitor is connected with described first filter circuit, and the smooth direct current electricity using described first filter circuit output is charged；
Described PWM controller is connected with described charging capacitor, after the voltage of described charging capacitor reaches the startup voltage of PWM controller, output pulse width modulation (PWM) signal drives described metal-oxide-semiconductor to realize opening and closing so that being changed into alternating current by the electric current of transformator；
Described metal-oxide-semiconductor is connected with PWM controller and transformator respectively, realizes opening and closing according to the pwm signal of PWM controller output；
Described second rectification circuit is connected with described transformator, and the alternating current of described transformator output is become Rectified alternating current；
Described second filter circuit is connected with described second rectification circuit, the Rectified alternating current of described second rectification circuit output is converted into smooth direct current and supplies electricity to load supplying.
Preferably：The other road alternating current that described transformator produces, after passing sequentially through rectification, current limliting and Filtering Processing, is converted into smooth direct current and supplies electricity to described PWM controller powering.
From technique scheme as can be seen that the present invention provide protective circuit of switch power source, by increasing by the second over-current protecting element（Such as second fuse）, by the second over-current protecting element and overvoltage protection element（Such as varistor）Series connection, then when the electric current of overvoltage protection element increases and temperature exceedes given threshold, this second over-current protecting element will disconnect automatically, thus protecting the second over-current protecting element（Such as varistor）Will not constantly heat up the blast finally resulting in, the phenomenon such as catch fire because of inside, thus effective protection switching power circuit, protect the use safety of user.
Brief description
In order to be illustrated more clearly that the embodiment of the present invention or technical scheme of the prior art, the accompanying drawing of required use in embodiment or description of the prior art will be briefly described below, apparently, drawings in the following description are only some embodiments of the present invention, for those of ordinary skill in the art, on the premise of not paying creative work, can also obtain other accompanying drawings according to these accompanying drawings.
Below in conjunction with accompanying drawing, the present invention will be further described, in accompanying drawing：
Fig. 1 is prior art switching power circuit protection circuit schematic diagram；
Fig. 2 is switching power circuit protection circuit schematic diagram of the present invention；
Fig. 3 is switching power circuit schematic diagram of the present invention；
Fig. 4 is Switching Power Supply protection device structural representation of the present invention.
Specific embodiment
Below in conjunction with the accompanying drawing in the embodiment of the present invention, the technical scheme in the embodiment of the present invention is clearly and completely described it is clear that described embodiment is only a part of embodiment of the present invention, rather than whole embodiments.Based on the embodiment in the present invention, all other embodiment that those of ordinary skill in the art are obtained under the premise of not making creative work, broadly fall into the scope of protection of the invention.
The present invention puies forward a kind of protective circuit of switch power source, protection device and Switching Power Supply, energy more effectively protection switch power circuit, and protection user uses safety.
Below in conjunction with the accompanying drawings, present disclosure is discussed in detail.
Fig. 2 is switching power circuit protection circuit schematic diagram of the present invention.As shown in Fig. 2 in the Switching Power Supply input terminal protecting circuit of the present invention, control circuit is mainly made up of overvoltage protection element, over-current protecting element and part of its periphery circuit.The overvoltage protection element of the present invention, can be varistor but be not limited to this or other have the element of over-voltage protection function, the over-current protecting element of the present invention, can be fuse（Also referred to as electric fuse）But be not limited to this or other have the element of excess current protective function.
The fuse that the present invention uses, can be high fusing-off temperature fuse（Also referred to as high fusing-off temperature electric fuse）F, the varistor that the present invention uses, can be high joule MOV（Metal Oxide Varistor, metal-oxide varistor）, wherein joule is the unit of energy, and high joule MOV is also referred to as high-energy MOV.
Specifically, on the circuit shown in Fig. 2, invention increases high fusing-off temperature electric fuse F2（Specifications parameter is T=130 DEG C of 5A/250V, represents maximum current 5A, ceiling voltage 250V, 130 DEG C of maximum temperature）, and electric fuse F2 is entangled with varistor MOV sleeve pipe, consolidated.This sleeve pipe can be heat-shrinkable T bush but be not limited to this or other kinds of sleeve pipe.In Fig. 2, varistor MOV is connected in parallel between the live wire of power input and zero line；Electric fuse F1 is in parallel with described varistor；
Electric fuse F2 is connected with described varistor MOV, disconnects when the electric current of described varistor MOV increases and temperature exceedes given threshold.Also has D1-D4 in Fig. 2（Diode）The bridge rectifier of composition, is used for converting alternating current to Rectified alternating current.One end of electric fuse F1 is connected with one end of bridge rectifier, and the other end of F1 is connected with one end of MOV；The other end of MOV is connected with the other end of bridge rectifier, and MOV is also entangled with electric fuse F2 heat-shrinkable T bush.
So, work as MOV
Electric current increases, and when heating leads to temperature to rise to uniform temperature, electric fuse F2 will fuse, thus cut-off loop is not it is ensured that MOV occurs the potential safety hazard such as explode or catch fire because overheated.And in the protection circuit of prior art, when MOV heating exceedes uniform temperature, electric fuse F1 can't disconnect, therefore cannot avoid MOV that the potential safety hazard such as explode or catch fire occurs because overheated.So, the circuit after present invention improvement, not only more effectively suppresses to wave stream voltage, and secure context is preferably ensured.
Fig. 3 is switching power circuit schematic diagram of the present invention.The figure illustrates than more complete switching power circuit.As shown in figure 3, the workflow of this circuit is：
First, the 100-240V of input（Volt）AC alternating current first pass around this two surge protector component of electric fuse F1 and MOV1 after, then through the present invention increase electric fuse F2 be added on D1-D4（Diode）On bridge rectifier.When MOV heating leads to temperature to rise to uniform temperature threshold value, F2 will fuse, thus cut-off loop, it is to avoid there is the potential safety hazard such as explode or catch fire because overheated in MOV.This uniform temperature threshold value, can rule of thumb carry out value, for example, can be 130 DEG C but be not limited to this, such as can also be 120 DEG C or 140 DEG C etc..
After the diode D1-D4 rectification of the rectified circuit of alternating current, it is changed into Rectified alternating current, the electric capacity C1 of filtered circuit, inductance L1, the filtering of these three filter elements of electric capacity C3 again of this Rectified alternating current, it is transformed into smooth direct current electricity.This smooth unidirectional current first passes through resistance R10, R11 and is charged to charging capacitor C4.
When the voltage on electric capacity C4 reaches PWM（Pulse Width Modulation, pulse width modulation）After the startup voltage of controller U1, PWM controller U1 starts, and by 6 foot output pwm signals, drives metal-oxide-semiconductor through R7, R9 resistor network（Metal-Oxide-Semiconductor, metal oxide semiconductor transistor）Q1, realizes the opening and closing of metal-oxide-semiconductor（ON-OFF）Making by the electric current of transformator T1 is alternating current, this alternating current produces the magnetic field of alternation in inside transformer, secondary coil can produce alternating current after sensing alternating magnetic field, it is converted into Rectified alternating current through diode D7 or D8 rectification shape, filter through electric capacity C8, C9 again, be converted into smooth direct current electricity output, powering load.
Another road, the coil-induced of assists winding also can produce alternating current to after alternating magnetic field, after diode D6 rectification, resistance R5 current limliting, electric capacity C4 filtering, be converted into smooth direct current electricity, power to PWM controller U1.
In addition, R16, R18, R15, C7, R12, R13, PC1, C5's of in figure is combined as sampling mu balanced circuit, the error signal of this electric circuit inspection exporting the 2nd foot of U1, thus controlling switching frequency and the dutycycle of PWM, realizing stablizing of output voltage.
The OCP of circuit in Fig. 3（The too high protection of electric current）The realization of function is to be protected by these elements of R1, R2, Cx, R4, C2.When current is excessive, R1 overtension on R2, this voltage signal, after Cx, R4, C2 filtering, is added on the 4th foot of U1, thus controlling U1 to stop output pwm signal.
In Fig. 3 D5, R3, R6, C6 of circuit be combined as peak absorbing circuit, the peak voltage preventing the D pole of Q1 is too high and damages metal-oxide-semiconductor.
Fig. 4 is Switching Power Supply protection device structural representation of the present invention.As shown in figure 4, Switching Power Supply protection device 400 comprises above-mentioned protective circuit of switch power source 401, referring to previously mentioned, here is omitted for the specific descriptions of protective circuit of switch power source 401.
In sum, the protective circuit of switch power source that the present invention provides, by increasing by the second over-current protecting element（Such as second fuse）, by the second over-current protecting element and overvoltage protection element（Such as varistor）Series connection; so overvoltage protection element electric current increase and temperature exceed given threshold when; this second over-current protecting element will disconnect automatically; thus protecting the second over-current protecting element constantly will not heat up the blast finally resulting in, the phenomenon such as catch fire because of inside; thus effective protection switching power circuit, protect the use safety of user.
The technical scheme above embodiment of the present invention being provided, it is described in detail, specific case used herein is set forth to the principle of the present invention and embodiment, and the explanation of above example is only intended to help and understands the method for the present invention and its core concept；Simultaneously for one of ordinary skill in the art, according to the thought of the present invention, all will change in specific embodiments and applications, in sum, this specification content should not be construed as limitation of the present invention.
Claims (10)
1. a kind of protective circuit of switch power source it is characterised in that：
Described protection circuit includes overvoltage protection element, the first over-current protecting element and the second over-current protecting element；Wherein,
Described overvoltage protection element is connected in parallel between the live wire of power input and zero line；
Described first over-current protecting element is in parallel with described overvoltage protection element；
Described second over-current protecting element is connected with described overvoltage protection element, disconnects when the electric current of described overvoltage protection element increases and temperature exceedes given threshold.
2. protective circuit of switch power source according to claim 1 it is characterised in that：
Described overvoltage protection element is varistor, and described first over-current protecting element is first fuse, and described second over-current protecting element is second fuse；
Described varistor is connected in parallel between the live wire of power input and zero line；
Described first fuse is in parallel with described varistor；
Described second fuse is connected with described varistor, disconnects when the electric current of described varistor increases and temperature exceedes given threshold.
3. protective circuit of switch power source according to claim 2 it is characterised in that：
Described second fuse is entangled using sleeve pipe with described varistor.
4. the protective circuit of switch power source according to Claims 2 or 3 it is characterised in that：
Described protection circuit also includes rectification circuit, is used for converting alternating current to Rectified alternating current；
One end of described first fuse is connected with one end of described rectification circuit, and the other end of described first fuse is connected with one end of described varistor；
The other end of described varistor is connected with the other end of described rectification circuit.
5. the protective circuit of switch power source according to Claims 2 or 3 it is characterised in that：
Described second fuse is high fusing-off temperature fuse, and described varistor is high-energy metal-oxide varistor.
6. protective circuit of switch power source according to claim 3 it is characterised in that：
Described sleeve pipe is heat-shrinkable T bush.
7. a kind of Switching Power Supply protection device is it is characterised in that comprise the protective circuit of switch power source described in any one of the claims 1 to 6.
8. a kind of Switching Power Supply is it is characterised in that comprise the protective circuit of switch power source described in any one of the claims 1 to 6.
9. Switching Power Supply according to claim 8 it is characterised in that：
Described Switching Power Supply also includes the first filter circuit, charging capacitor, pulse width modulation (PWM) controller, metal-oxide semiconductor (MOS) crystal metal-oxide-semiconductor, transformator, the second rectification circuit, the second filter circuit；
Described first filter circuit, after the alternating current of described power input is changed into Rectified alternating current by the rectification circuit in described protective circuit of switch power source, described Rectified alternating current is transformed into smooth direct current electricity；
Described charging capacitor is connected with described first filter circuit, and the smooth direct current electricity using described first filter circuit output is charged；
Described PWM controller is connected with described charging capacitor, after the voltage of described charging capacitor reaches the startup voltage of PWM controller, output pulse width modulation (PWM) signal drives described metal-oxide-semiconductor to realize opening and closing so that being changed into alternating current by the electric current of transformator；
Described metal-oxide-semiconductor is connected with PWM controller and transformator respectively, realizes opening and closing according to the pwm signal of PWM controller output；
Described second rectification circuit is connected with described transformator, and the alternating current of described transformator output is become Rectified alternating current；
Described second filter circuit is connected with described second rectification circuit, the Rectified alternating current of described second rectification circuit output is converted into smooth direct current and supplies electricity to load supplying.
10. Switching Power Supply according to claim 9 it is characterised in that：
The other road alternating current that described transformator produces, after passing sequentially through rectification, current limliting and Filtering Processing, is converted into smooth direct current and supplies electricity to described PWM controller powering.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201510473275.1A CN106451350A (en) | 2015-08-05 | 2015-08-05 | Switching power supply protection circuit and device and switching power supply |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201510473275.1A CN106451350A (en) | 2015-08-05 | 2015-08-05 | Switching power supply protection circuit and device and switching power supply |
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| CN202979395U (en) * | 2012-11-27 | 2013-06-05 | 昂宝电子（上海）有限公司 | Novel LED driving circuit |
| CN103475238A (en) * | 2012-06-08 | 2013-12-25 | 鸿富锦精密工业（深圳）有限公司 | Voltage conversion circuit |
| CN204633323U (en) * | 2015-04-29 | 2015-09-09 | 深圳市福佳电器有限公司 | A kind of protective circuit of anti-lightning surge and the Switching Power Supply of application thereof |
| CN204992533U (en) * | 2015-08-05 | 2016-01-20 | 惠州市忠邦电子有限公司 | Switching power supply protection circuit, protection device and switching power supply |
-
2015
- 2015-08-05 CN CN201510473275.1A patent/CN106451350A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN2627635Y (en) * | 2003-05-27 | 2004-07-21 | 俞国麟 | Lightning protection socket |
| CN103475238A (en) * | 2012-06-08 | 2013-12-25 | 鸿富锦精密工业（深圳）有限公司 | Voltage conversion circuit |
| CN202979395U (en) * | 2012-11-27 | 2013-06-05 | 昂宝电子（上海）有限公司 | Novel LED driving circuit |
| CN204633323U (en) * | 2015-04-29 | 2015-09-09 | 深圳市福佳电器有限公司 | A kind of protective circuit of anti-lightning surge and the Switching Power Supply of application thereof |
| CN204992533U (en) * | 2015-08-05 | 2016-01-20 | 惠州市忠邦电子有限公司 | Switching power supply protection circuit, protection device and switching power supply |
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Application publication date: 20170222 |
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