CN201608519U - Overcurrent protective circuit - Google Patents
Overcurrent protective circuit Download PDFInfo
- Publication number
- CN201608519U CN201608519U CN2010201216797U CN201020121679U CN201608519U CN 201608519 U CN201608519 U CN 201608519U CN 2010201216797 U CN2010201216797 U CN 2010201216797U CN 201020121679 U CN201020121679 U CN 201020121679U CN 201608519 U CN201608519 U CN 201608519U
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- triode
- resistance
- load
- circuit
- audion
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Abstract
The utility model discloses an overcurrent protective circuit which is reliable, practical, simple and effective. The overcurrent protective circuit includes three resistances and two NPN audions; the base of the audion T1 is connected with the resistance R1 in series and then is connected with one end of a load and the collector of the audion T2; the collector of the audion T1 is connected with the other end of the load and the anode of a power through the resistance R2; the collector of the audion T1 is also connected with the base of the audion T2 through the resistance R3; and both the emitters of the audion T1 and the audion T2 are connected with the cathode of the power.
Description
Technical field
The utility model relates to a kind of circuit, more specifically to a kind of circuit overcurrent protection, belongs to field of power electronics.
Background technology
Along with the electronic technology development; circuit protection is towards the aspect development of comprehensive and complexity; various protection chips go out in succession; defencive function is a lot; such as excess temperature; overcurrent; overvoltage; under-voltage; short circuit etc., but to power model,, all protections finish if all being placed on a chip; in a single day chip goes wrong; will have serious consequences, make all protections all go wrong, might be with the power cell damage of costliness; so should be independent several significant element protections; so in a single day, go wrong, other can also play the certain protection effect for the time being, is unlikely to produce so big risk.Extremely important such as the driving power in frequency converter work; be directly connected to the operating state of inversion; in a single day power supply goes wrong; whole inversion process can't be finished; so the protection operation irregularity of driving power is important; wherein most important is it possible that overcurrent protection; in order to prevent the power supply overcurrent; need a kind of very simple but effective protective circuit of exploitation; and when surpassing the setting electric current; circuit meeting automatic current limiting makes power supply work in rated range all the time, has protected power supply to make that just inversion work is more smooth.
Summary of the invention
The utility model provides a kind of circuit overcurrent protection, and this circuit performance is reliable and practical, and is effectively simple.
The technical solution of the utility model is as follows:
The utility model circuit overcurrent protection; it includes 3 resistance and 2 NPN triodes; resistance R of base stage polyphone 1 back of triode T1 is connected with load one end and triode T2 collector electrode; the collector electrode of triode T1 is connected with the other end of load and the positive pole of power supply by a resistance R 2; the collector electrode of triode T1 also is connected with triode T2 base stage by a resistance R 3, and the emitter of triode T1 and triode T2 all is connected with the negative pole of power supply.
Circuit overcurrent protection of the present utility model; its further technical scheme is: when the working power of the IGBT of circuit requirement protection be 3W, maximal work electric current be 0.2A, when virtual voltage is 16V; the value of resistance R 1 is 10K; the value of R2 is 1K; the value of R3 is 4.7K, and the HFE of triode T1 and triode T2 is 100.
The utlity model has following beneficial effect:
Circuit performance of the present utility model is reliable and practical, and is with low cost, simple effectively load current surpasses the condition that limits, and will protect power supply automatically.
Description of drawings
Fig. 1 is an electrical block diagram of the present utility model
Embodiment
Below in conjunction with accompanying drawing the utility model technology contents is explained:
As shown in Figure 1, a kind of current protecting circuit of the present utility model, it includes 3 resistance and 2 NPN triodes, resistance R of base stage polyphone 1 back of triode T1 is connected with load one end and triode T2 collector electrode, the collector electrode of triode T1 is connected with the other end of load and the positive pole of power supply by a resistance R 2, the collector electrode of triode T1 also is connected with triode T2 base stage by a resistance R 3, and the emitter of triode T1 and triode T2 all is connected with the negative pole of power supply; When the working power of the IGBT of circuit requirement protection be 3W, maximal work electric current be 0.2A, when virtual voltage is 16V, the value of resistance R 1 is 10K, the value of R2 is 1K, the value of R3 is 4.7K, the HFE of triode T1 and triode T2 is 100.
The work of circuit is process roughly: being known that by top rated operational current is 0.2A, is 0.2A so establish the maximal work electric current here, and target is when load is excessive, and output current can not be greater than 0.2A.Here suppose that load is a resistance, because the dividing potential drop effect of T2, practical power voltage is generally 16V, and load has only 15V, that is to say that T2 goes up collection radio pressure and is 1V.So, be easy to obtain its resistance and be about 75 ohm.Like this, if load impedance less than 75 ohm, electric current will be limited in the 0.2A, when load impedance during greater than 75 ohm, load current can be greater than 0.2A, electric current is decided along with the load size cases.
Determine the operating state on the limit point of 0.2A earlier, when load is 75 ohm, electric current is 0.2A, and load voltage is 15V, meets condition of work, counter shifting onto on the T2, the T2 base current is 2mA, and the last voltage of R3 is 9.4V, adds the basic emitter voltage 0.6V on the T2 in addition, can obtain the last voltage of R2 is 6V, know that R2 resistance is 1K, obtaining the last electric current of R2 is 6mA, deducts R3 and goes up electric current 2mA, so the last collection of T1 emitter current is 4mA, the last base current of the counter again T1 of shifting onto is 0.04mA, and obtaining the last voltage of R1 is 0.4V, and the basic emitter voltage of adding T1 is 0.6V, collection emitter-base bandgap grading pressure drop on the T2 is 1V, with pre-conditioned consistent.
Suppose again that below two kinds of situations come the operating state of proof scheme:
When load impedance the time greater than 75 ohm, that is to say when load diminishes, suppose that load voltage is constant this moment, so upward base current is constant for T1, the collected current of T1 is also constant, so the last voltage of R2 is constant, so that T2 goes up the base current no change,, become big restriction but be subjected to load impedance so the T2 collected current is constant, electric current can satisfy imposing a condition less than 0.2A.
When load impedance the time less than 75 ohm; that is to say when load becomes big; suppose that load current is constant this moment, but load voltage can diminish, and can become big so the collection radio on the T2 is pressed; so that the base current on the T1 can become big; so the collector current on the T1 also can become greatly thereupon, cause R2 to go up voltage and increase, but the base current on the R3 can reduce; come the colleeting comb of restricted T 2 further to reduce like this, thereby reached the purpose of protection power supply.
Claims (2)
1. circuit overcurrent protection; it is characterized in that including 3 resistance and 2 NPN triodes; resistance R of base stage polyphone 1 back of triode T1 is connected with load one end and triode T2 collector electrode; the collector electrode of triode T1 is connected with the other end of load and the positive pole of power supply by a resistance R 2; the collector electrode of triode T1 also is connected with triode T2 base stage by a resistance R 3, and the emitter of triode T1 and triode T2 all is connected with the negative pole of power supply.
2. circuit overcurrent protection according to claim 1; it is characterized in that: when the working power of the IGBT of circuit requirement protection be 3W, maximal work electric current be 0.2A, when virtual voltage is 16V; the value of resistance R 1 is 10K; the value of R2 is 1K; the value of R3 is 4.7K, and the HFE of triode T1 and triode T2 is 100.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2010201216797U CN201608519U (en) | 2010-03-02 | 2010-03-02 | Overcurrent protective circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2010201216797U CN201608519U (en) | 2010-03-02 | 2010-03-02 | Overcurrent protective circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN201608519U true CN201608519U (en) | 2010-10-13 |
Family
ID=42953220
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN2010201216797U Expired - Lifetime CN201608519U (en) | 2010-03-02 | 2010-03-02 | Overcurrent protective circuit |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN201608519U (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101771272A (en) * | 2010-03-02 | 2010-07-07 | 南京亚派科技实业有限公司 | Over current protection circuit |
| CN105468078A (en) * | 2015-12-30 | 2016-04-06 | 马瑞利汽车电子(广州)有限公司 | Active current limiting circuit with no branches leaking currents |
-
2010
- 2010-03-02 CN CN2010201216797U patent/CN201608519U/en not_active Expired - Lifetime
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101771272A (en) * | 2010-03-02 | 2010-07-07 | 南京亚派科技实业有限公司 | Over current protection circuit |
| CN101771272B (en) * | 2010-03-02 | 2013-02-13 | 南京亚派科技实业有限公司 | Over current protection circuit |
| CN105468078A (en) * | 2015-12-30 | 2016-04-06 | 马瑞利汽车电子(广州)有限公司 | Active current limiting circuit with no branches leaking currents |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| AV01 | Patent right actively abandoned |
Granted publication date: 20101013 Effective date of abandoning: 20130227 |
|
| RGAV | Abandon patent right to avoid regrant |