CN202142836U - Over-current signal detection circuit - Google Patents
Over-current signal detection circuit Download PDFInfo
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- CN202142836U CN202142836U CN201120138391U CN201120138391U CN202142836U CN 202142836 U CN202142836 U CN 202142836U CN 201120138391 U CN201120138391 U CN 201120138391U CN 201120138391 U CN201120138391 U CN 201120138391U CN 202142836 U CN202142836 U CN 202142836U
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Abstract
The utility model relates to an over-current signal detection circuit which includes an over-current comparison circuit, an insolating element, and a trigger. The over-current comparison circuit includes a first input terminal, a second input terminal, and an output terminal. The first input terminal inputs a detecting signal, and the second input terminal inputs a reference voltage. The insolating element includes a first terminal and a second terminal, and the first terminal and a first power supply are connected with the output terminal of an over-current comparator, and the second terminal is connected with a second power supply. The isolating element is switched on when the detecting signal is bigger than the reference voltage, and the current flows from a second voltage source to the earth of a first voltage source. The isolating element is switched off when the detecting signal is smaller than the reference voltage. The trigger includes a setting terminal which is connected with the second terminal of the isolating element, and outputs a first signal when the isolating element is switched on and outputs a second signal when the isolating element is switched off. The over-current signal detection circuit can detect various over-current signals, and is especially suitable for the detection of a short-time over-current signal.
Description
Technical field
The utility model relates to testing circuit, relates in particular to the over-current signal testing circuit that is used to detect over-current signal.
Background technology
In power electronic equipments such as inverter, ups power, need to detect the size of current of input and output, in case surpass the load current value of system requirements, off switch pipe at once, halt system work reaches the purpose of protection system.
As shown in Figure 1, existing over-current detection circuit comprises current detecting amplifying circuit 1, voltage comparator 2 and bleeder circuit 3.Current detecting amplifying circuit 1 is made up of operational amplifier, input termination voltage input signal Uin.The inverting input of voltage comparator 2 is connected with the output of current detecting amplifying circuit 1, and in-phase input end is connected with bleeder circuit 3, and output Uout links to each other with the control circuit of connected system.Bleeder circuit 3 comprises resistance R 2 and resistance 3, and first end of resistance R 2 is as the input of bleeder circuit 3, and in order to input reference voltage Vref, second end is connected with first end of resistance R 3.The second end ground connection of resistance R 3.Second end of resistance R 2 and first end of resistance R 3 are as the output of bleeder circuit 3, and the output of bleeder circuit 3 is connected with the in-phase input end of voltage comparator 2.
As shown in Figure 1, the course of work of above-mentioned current detection circuit is following: current sense amplifier is used for current signal I is detected amplification, gives the inverting input of voltage comparator 2 then, and this current signal I converts voltage signal Uin into through resistance R 1.Because the input of the in-phase input end of voltage comparator 2 has voltage Vref; If there is overcurrent to take place, the output voltage U in of current sense amplifier 1 can be greater than Vref, voltage comparator 2 output switching activities, thus detected over-current signal, this signal is passed to control circuit, the control circuit shutdown system, thereby, protection system.
As shown in Figure 1, though above-mentioned over-current detection circuit can reach the purpose of current detecting,, still there is following shortcoming in above-mentioned current detection circuit:
1, because the accuracy limitations of current sense amplifier 1 and voltage comparator 2 itself, above-mentioned overcurrent testing circuit can not be applicable to that high-precision current detects occasion.
2, above-mentioned current detection circuit can not detect the overcurrent pulse in the short time; Because; The output of above-mentioned over-current detection circuit remains a switching value that changes with electric current; In case have overcurrent to take place, voltage comparator 2 inverting input level Uin can be higher than the Vref of in-phase input end, voltage comparator 2 overturns and output low level; But after overcurrent finished, voltage comparator 2 reverted to high level, system restoration operate as normal at once again; If the overcurrent time of origin is very short, be an overcurrent spike signal, then recover again at once voltage comparator 2 output voltages upset back, because the time-delay of circuit, control circuit is shutdown system in time, thereby might damage main switching device.A kind of in addition method is to use high-precision operational amplifier to constitute current detection circuit.But this method is the same with use integrated circuit formation current detection circuit, and output remains a switching value, also can't detect the overcurrent pulse of short time.
Summary of the invention
The problem that the utility model solves is the problem that existing over-current detection circuit can not detect the overcurrent pulse in the short time.
For addressing the above problem; The over-current signal testing circuit of the utility model comprises overcurrent comparison circuit, isolated component and trigger; The overcurrent comparison circuit comprises first input end, second input and output, first input end input detection signal, the second input input reference voltage; Isolated component comprises first end and second end; This first end is connected with the output of first power supply with the overcurrent comparator; Second end connects second source; Said isolated component is in detection signal conducting during greater than reference voltage, and electric current flows to the ground of first voltage source from second voltage source, and isolated component turn-offs during less than reference voltage at detection signal; Trigger comprises the set end, and this set end is connected with second end of isolated component, when the isolated component conducting, exports first signal, output secondary signal when isolated component turn-offs.
Alternatively, isolated component is diode, positive-negative-positive switch triode or isolates a kind of in the optocoupler.
Alternatively, said trigger is a rest-set flip-flop.
Alternatively; Said overcurrent comparison circuit comprises comparator and bleeder circuit; The inverting input of comparator is first end of said overcurrent comparison circuit, and the in-phase input end of said comparator is connected with bleeder circuit, and the input of bleeder circuit is second input of said overcurrent comparison circuit.
Alternatively, said comparator is the specialized voltages comparator, and said bleeder circuit is the resistance-type bleeder circuit.
Compared with prior art, the utlity model has following advantage:
1, because the utility model comprises isolated component and trigger, when the over-current signal of carving in short-term produced, over-current detection circuit output signal made the isolated component conducting; Electric current flows to the ground of first power supply from second source; Thereby trigger deflects and exports first signal to control circuit, the action of control circuit control system; Thereby, protection system.When over-current signal was not arranged, isolated component turn-offed, and trigger can not deflect and export secondary signal, and system works on; Thus, isolated component and trigger are formed latch, can over-current signal be latched, so; The utility model not only can detect various over-current signals, can detect the over-current signal of carving in short-term especially, and, as long as the utility model has over-current signal to produce; Isolated component will conducting, thereby the utility model is highly sensitive.
2, since the overcurrent comparison circuit of the utility model by voltage comparator constitute, isolated location is by diode, positive-negative-positive switch triode or isolate a kind of in the optocoupler, trigger is a rest-set flip-flop, so the utility model is simple in structure, cost is low.
3, because the overcurrent comparison circuit of the utility model comprises comparator and bleeder circuit, and bleeder circuit can provide dividing potential drop accurately, so accuracy of detection is high.
Description of drawings
Fig. 1 is the structural representation of existing overcurrent testing circuit;
Fig. 2 is the theory diagram of the utility model over-current detection circuit;
Fig. 3 is the physical circuit figure of the utility model over-current detection circuit.
Embodiment
In order to make the utility model more clear and easy to understand, below special case lift embodiment and combine diagram to describe.
As shown in Figures 2 and 3, the over-current detection circuit of the utility model comprises overcurrent comparison circuit 4, isolated component 5 and trigger 6.Overcurrent comparison circuit 4 comprises comparator 41 and bleeder circuit, and the inverting input of comparator 41 is used to import detection signal through the output of resistance R 1 connection detection circuit, and the inverting input of comparator 41 is as the first input end of over-current detection circuit 4.Bleeder circuit comprises resistance R 2 and resistance R 3.One end input reference voltage Vref of resistance R 2, as second input of overcurrent comparison circuit, the other end is connected with resistance R 3.The other end ground connection of resistance R 3, resistance R 3 are connected the in-phase input end of comparator 41 with the intermediate node of resistance R 2.
As shown in Figures 2 and 3, isolated location 5 comprises first end and second end, and first end of isolated location 5 is through resistance R 4 and first power supply 7 (shown in Figure 3 is VCC1), and second end of isolated location 5 connects second source 8 (shown in Figure 3 is VCC2) through resistance R 5.Isolated location 5 is diode, positive-negative-positive switch triode or isolates a kind of in the optocoupler, is diode D1 in the present embodiment.
As shown in Figures 2 and 3, trigger 6 is the rest-set flip-flops that are made up of NAND gate N1 and NAND gate N2, and wherein, the set end is connected with second end of isolated component 5, the reset circuit input reset signal that reset terminal constitutes through resistance R 6 and capacitor C 2.
As shown in Figures 2 and 3, the course of work of the utility model is following:
The bleeder circuit that resistance R 2 and resistance R 3 constitute obtains the in-phase input end that a reference level Vref1 gives comparator 41 after to reference voltage V ref dividing potential drop, and current signal I is connected to the inverting input Uin of comparator 41.Under normal operation; Current signal I is less than reference level Vref1, and comparator 41 output high level are because the reverse isolation effect of diode D1; And power supply VCC2 and process resistance R 6 make that with capacitor C 2 input of NAND gate N2 is a high level; So the rest-set flip-flop that is made up of NAND gate N1 and NAND gate N2 can not move, exporting constant is high level.In case stream took place, even very short overcurrent spike of time, comparator 41 outputs can be overturn; Become low level, at this moment, diode D1 conducting; Electric current flows to the ground of first voltage source 7 (Vcc1) from second voltage source 8 (Vcc2), and the input of NAND gate N1 becomes low level by high level, and the input of NAND gate N2 is still drawn high into high level by second source 8 (Vcc2); So trigger can overturn, output becomes low level by high level; At this moment, even if input over-current signal I disappears, because the triggering latch function of trigger, output Uout is also constant to be low level, thereby has realized the reliable detection of overcurrent.Have only to behind low level pulse of RESET, this pulse signal inputs to the input of NAND gate N2, so the output Uout of trigger 6 just can overturn again and become high level, then this over-current detection circuit gets into detected state again.
In sum, because the utility model comprises isolated component and trigger, when the over-current signal of carving in short-term produces; Over-current detection circuit output signal makes the isolated component conducting, and electric current flows to the ground of first power supply from second source, thereby; Trigger deflects and exports first signal to control circuit; The action of control circuit control system, thereby, protection system.When over-current signal was not arranged, isolated component turn-offed, and trigger can not deflect and export secondary signal, and system works on.Thus, isolated component and trigger are formed latch, can over-current signal be latched.So the utility model not only can detect various over-current signals, can detect especially the over-current signal at quarter in short-term, and as long as the utility model has the over-current signal generation, isolated component will conducting, thereby the utility model is highly sensitive.In addition, the overcurrent comparison circuit of the utility model is the specialized voltages comparator by the voltage comparator front, inconsistent formation; Isolated location is by diode, positive-negative-positive switch triode or isolate a kind of in the optocoupler, and trigger is a rest-set flip-flop, so; The utility model is simple in structure, and cost is low.Moreover because the overcurrent comparison circuit of the utility model comprises comparator and bleeder circuit, bleeder circuit can provide dividing potential drop accurately, so accuracy of detection is high.
Claims (4)
1. the over-current signal testing circuit is characterized in that, comprises overcurrent comparison circuit, isolated component and trigger,
The overcurrent comparison circuit comprises first input end, second input and output, first input end input detection signal, the second input input reference voltage;
Isolated component comprises first end and second end; This first end is connected with the output of first power supply with the overcurrent comparator; Second end connects second source; Said isolated component is in detection signal conducting during greater than reference voltage, and electric current flows to the ground of first voltage source from second voltage source, and isolated component turn-offs during less than reference voltage at detection signal;
Trigger comprises the set end, and this set end is connected with second end of isolated component, when the isolated component conducting, exports first signal, output secondary signal when isolated component turn-offs.
2. over-current signal testing circuit as claimed in claim 1 is characterized in that, isolated component is diode, positive-negative-positive switch triode or isolates a kind of in the optocoupler.
3. over-current signal testing circuit as claimed in claim 1 is characterized in that said trigger is a rest-set flip-flop.
4. over-current signal testing circuit as claimed in claim 1; It is characterized in that; Said overcurrent comparison circuit comprises comparator and bleeder circuit; The inverting input of comparator is first end of said overcurrent comparison circuit, and the in-phase input end of said comparator is connected with bleeder circuit, and the input of bleeder circuit is second input of said overcurrent comparison circuit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201120138391U CN202142836U (en) | 2011-04-29 | 2011-04-29 | Over-current signal detection circuit |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201120138391U CN202142836U (en) | 2011-04-29 | 2011-04-29 | Over-current signal detection circuit |
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| CN202142836U true CN202142836U (en) | 2012-02-08 |
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| CN201120138391U Expired - Fee Related CN202142836U (en) | 2011-04-29 | 2011-04-29 | Over-current signal detection circuit |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR20140011932A (en) * | 2012-07-19 | 2014-01-29 | 페어차일드 세미컨덕터 코포레이션 | Over-current detection circuit and method for power switch |
| CN103994862A (en) * | 2014-06-04 | 2014-08-20 | 安徽江淮汽车股份有限公司 | Leakage detecting circuit |
| CN104377662A (en) * | 2013-08-12 | 2015-02-25 | 伊顿公司 | Ultra-fast hardware current-limiting circuit |
| CN109147692A (en) * | 2018-08-31 | 2019-01-04 | 重庆惠科金渝光电科技有限公司 | Driving circuit, drive system and display |
| CN109586697A (en) * | 2018-11-30 | 2019-04-05 | 大同煤矿集团衡安装备股份有限公司 | A kind of HA intrinsic safety electric source protection circuit plate |
-
2011
- 2011-04-29 CN CN201120138391U patent/CN202142836U/en not_active Expired - Fee Related
Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR20140011932A (en) * | 2012-07-19 | 2014-01-29 | 페어차일드 세미컨덕터 코포레이션 | Over-current detection circuit and method for power switch |
| CN103575964A (en) * | 2012-07-19 | 2014-02-12 | 快捷半导体(苏州)有限公司 | Over-current detection circuit and method for power switch tube |
| CN103575964B (en) * | 2012-07-19 | 2016-03-23 | 快捷半导体(苏州)有限公司 | A kind of over-current detection circuit of power switch pipe and method |
| US9551742B2 (en) | 2012-07-19 | 2017-01-24 | Fairchild Semiconductor Corporation | Circuit and method for overcurrent detection of power switch |
| KR102038428B1 (en) | 2012-07-19 | 2019-10-30 | 페어차일드 세미컨덕터 코포레이션 | Over-current detection circuit and method for power switch |
| CN104377662A (en) * | 2013-08-12 | 2015-02-25 | 伊顿公司 | Ultra-fast hardware current-limiting circuit |
| CN104377662B (en) * | 2013-08-12 | 2018-05-08 | 山特电子（深圳）有限公司 | Very fast hardware current-limiting circuit |
| CN103994862A (en) * | 2014-06-04 | 2014-08-20 | 安徽江淮汽车股份有限公司 | Leakage detecting circuit |
| CN109147692A (en) * | 2018-08-31 | 2019-01-04 | 重庆惠科金渝光电科技有限公司 | Driving circuit, drive system and display |
| CN109586697A (en) * | 2018-11-30 | 2019-04-05 | 大同煤矿集团衡安装备股份有限公司 | A kind of HA intrinsic safety electric source protection circuit plate |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| EE01 | Entry into force of recordation of patent licensing contract |
Assignee: ZHEJIANG JEC NEW ENERGY TECHNOLOGY CO., LTD. Assignor: China Electronic Technology Group Corporation No.36 Research Institute Contract record no.: 2015330000200 Denomination of utility model: Over-current signal detection circuit Granted publication date: 20120208 License type: Exclusive License Record date: 20150715 |
|
| LICC | Enforcement, change and cancellation of record of contracts on the licence for exploitation of a patent or utility model | ||
| CF01 | Termination of patent right due to non-payment of annual fee | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20120208 Termination date: 20170429 |