CN210111587U - Short-circuit protection circuit - Google Patents
Short-circuit protection circuit Download PDFInfo
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- CN210111587U CN210111587U CN201921412464.8U CN201921412464U CN210111587U CN 210111587 U CN210111587 U CN 210111587U CN 201921412464 U CN201921412464 U CN 201921412464U CN 210111587 U CN210111587 U CN 210111587U
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Abstract
The utility model discloses a short-circuit protection circuit, which mainly comprises a controller circuit and a load circuit; the controller circuit comprises a switching device and a voltage stabilizing device, wherein the output end of the switching device is connected with the input end of the load circuit; a switching device for turning on/off a current flowing through the load circuit; the voltage stabilizing device is used for limiting the maximum current output from the output end of the switching device. The utility model discloses a voltage regulator device and current-limiting resistance come the current-limiting current value of injecing the controller circuit, realize switching on or breaking off with load circuit through the switching device to the realization plays the effect of protection controller circuit when load circuit electric current is great, and when load circuit resumes normally, the switching device also switches on once more, thereby reduces the incident.
Description
Technical Field
The utility model relates to a protection circuit field especially relates to a short-circuit protection circuit.
Background
In the existing markets of water pumps, fans and the like, the adopted controller needs to provide power supply or signals for external load components, so that electrical connection is inevitable. However, due to uncertain factors of the external environment, such as collision during installation or limited service life of the load components, the external load components are easily damaged, so that the current of the power supply terminal is increased, or the controller board card is damaged due to short circuit. Similar products circulating in the existing market all have more or less problems, when the current of a power supply end is too large or short-circuited, the circuit design in the whole product cannot provide effective protection for a controller, and finally safety accidents such as fire disasters and the like can be caused.
SUMMERY OF THE UTILITY MODEL
The utility model provides a short-circuit protection circuit aiming at the defects in the prior art, which comprises a controller circuit and a load circuit; the controller circuit comprises a current-limiting resistor, a switching device and a voltage stabilizing device, wherein the switching device is provided with three terminals comprising a first terminal, a second terminal and a third terminal; the third end of the switching device is connected with the input end of the load circuit; the voltage stabilizing device is coupled between the first end and the second end of the switching device; the current limiting resistor is coupled between the second end of the switching device and the voltage stabilizing device; the switching device is used for switching on/off the current flowing through the load circuit; the voltage stabilizing device is used for limiting the maximum current flowing through the current limiting resistor and the switching device;
when the short-circuit protection circuit starts the current flowing through the load circuit at the switching device, the current flows through the third end from the second end of the switching device of the controller circuit and then flows to the load circuit;
when the short-circuit protection circuit turns off the current flowing through the load circuit at the switching device, the current flows through the first end from the second end of the switching device of the controller circuit and then returns to the controller circuit itself.
Optionally, the load circuit comprises a load, and a parallel capacitor bank coupled in parallel with the load, the parallel capacitor bank comprising a first capacitor and a second capacitor, the first capacitor and the second capacitor being connected in parallel; and the common connection end of the load, the first capacitor and the second capacitor is connected with the third end of the switching device.
Optionally, a common connection end of the load, the first capacitor, the second capacitor and a third end of the switching device is connected to a direct current power supply; and the other common connection end of the load, the first capacitor and the second capacitor is grounded.
Optionally, the controller circuit further includes a first resistor, a common connection end where the first end of the switching device and the voltage regulator are connected is connected to one end of the first resistor, and the other end of the first resistor is grounded.
Optionally, the controller circuit further includes a third capacitor, a common connection end of the voltage regulator and the current limiting resistor is connected to one end of the third capacitor, and the other end of the third capacitor is grounded;
optionally, the controller circuit further includes a controller internal power supply, and the controller internal power supply inputs a supply voltage to the controller circuit through a common connection terminal of the voltage regulator device, the current limiting resistor, and the third capacitor.
Optionally, the switching device is a PNP type triode.
Further optionally, the voltage regulator device is a three-terminal regulator.
Optionally, the switching device is a P-channel MOSFET.
Optionally, the voltage regulator device is a voltage regulator tube.
The utility model discloses a joint design PNP type triode or P channel MOSFET at controller circuit control load circuit is as switching device to through voltage regulator device and current-limiting resistance's cooperation, make the size of the current-limiting current of flowing through current-limiting resistance can be injectd, thereby realize the current-limiting of controller circuit, make load circuit under the condition of presenting problems, if load circuit electric current is too big or during the short circuit, the controller circuit can in time break off the contact with load circuit, when load circuit resumes normally, the switching device resumes the state that second end and first end switched on again, thereby can protect the controller circuit, make the controller circuit not damaged, the reliability of controller circuit has been improved, potential safety hazard is reduced; simultaneously the utility model discloses circuit structure design is simple, low cost.
Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the invention without undue limitation to the invention. In the drawings:
fig. 1 is a schematic circuit diagram according to a first embodiment of the present invention;
fig. 2 is a schematic diagram of a circuit loop in normal operation according to an embodiment of the present invention;
fig. 3 is a schematic diagram of a circuit loop when the load circuit current is too large according to an embodiment of the present invention;
fig. 4 is a schematic circuit diagram according to a second embodiment of the present invention.
Detailed Description
In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the drawings of the embodiments of the present invention are combined below to clearly and completely describe the technical solution of the embodiments of the present invention. It is to be understood that the embodiments described are only some of the embodiments of the present invention, and not all of them. All other embodiments, which can be obtained by a person skilled in the art without any inventive work based on the described embodiments of the present invention, belong to the protection scope of the present invention.
Unless defined otherwise, technical or scientific terms used herein shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention belongs. The use of "first," "second," and similar terms in the description and in the claims does not indicate any order, quantity, or importance, but rather is used to distinguish one element from another. Also, the use of the terms "a" or "an" and the like do not denote a limitation of quantity, but rather denote the presence of at least one.
The first embodiment is as follows:
the utility model discloses a short-circuit protection circuit, controller circuit pass through switching device and realize opening or closing load circuit's current output, and switching device receives voltage stabilizing device's steady voltage restriction for third terminal current obtains the restriction when switching on between switching device second end and the third terminal, thereby can restrict load current's maximum current. In the present invention, the short-circuit protection circuit includes a controller circuit and a load circuit; the controller circuit includes a switching device having three terminals including a first terminal, a second terminal, and a third terminal, and a voltage regulator device, an output terminal (i.e., the third terminal) of the switching device being connected to an input terminal of the load circuit. The on and off of the switch device is determined by the conduction of the second end and the third end, namely the switch device can control whether current flows through the load circuit. The voltage stabilizing device may then limit the maximum current output from the output of the switching device.
Fig. 1 is the utility model discloses an embodiment of short-circuit protection circuit in the utility model discloses a switching device adopts PNP type triode Q1, and switching device's first end is PNP type triode Q1's base promptly, and the second end is PNP type triode Q1's projecting pole promptly, and the third end is PNP type triode Q1's collecting electrode promptly, in the description of this embodiment, for convenient the differentiation, adopts the name introduction of base, projecting pole and collecting electrode. Specifically, as shown in fig. 1, the regulator device U1 is coupled in a circuit loop between the emitter and the base of the PNP transistor Q1, a current-limiting resistor R2 is coupled between the emitter of the PNP transistor Q1 and the regulator device U1, a common connection end between the base of the PNP transistor Q1 and the regulator device U1 is connected to one end of the first resistor R1, and the other end of the first resistor R1 is grounded. For convenience of description, a common connection terminal of the base of the PNP transistor Q1, the regulator device U1, and the first resistor R1 is referred to herein as a second common connection terminal. The controller circuit of this embodiment further includes a third capacitor C3, and a common connection terminal of the voltage regulator device U1 and the current-limiting resistor R2 is connected to one end of the third capacitor C3, and for convenience of description, the common connection terminal of the voltage regulator device U1, the current-limiting resistor R2, and the third capacitor C3 is referred to as a third common connection terminal; the other end of the third capacitor C3 is connected to the ground terminal of the first resistor R1 and is grounded together. The controller circuit further comprises a +5V controller internal power supply, and the controller internal power supply inputs the power supply voltage into the controller circuit through a third common connection end of a third capacitor C3, a voltage stabilizing device U1 and a current limiting resistor R2.
The load circuit of the present embodiment includes a load R3 and a parallel capacitor bank coupled in parallel across the load R3. The parallel capacitor bank comprises a first capacitor C1 and a second capacitor C2, and the first capacitor C1 is connected with the second capacitor C2 in parallel. Therefore, the load R3, the first capacitor C1 and the second capacitor C2 of the load circuit are all connected in parallel. For convenience of introduction, a common connection end of the load R3, the first capacitor C1 and the second capacitor C2 is connected to a collector of the PNP transistor Q1, and a common connection end of the load R3, the first capacitor C1, the second capacitor C2 and the collector of the PNP transistor Q1 is referred to as a first common connection end, and meanwhile, a direct current voltage VCC is also connected to the first common connection end and used for supplying power to a load circuit. The other common connection of the load R3, the first capacitor C1 and the second capacitor C2 is a fourth common connection, which is grounded.
Specifically, when the circuit normally works, the working loop of the circuit is as shown in fig. 2, that is, the +5V controller internal power supply supplies power to the controller circuit, and the dc voltage VCC supplies power to the load circuit, so as to form a loop of the +5V controller internal power supply, the current limiting resistor R2, the PNP type triode Q1, the dc voltage VCC, the load R3, and the third capacitor C3. When the load circuit has a problem, namely a large current appears at the first common connection end, the circuit enters a self-checking current-limiting mode, namely the working loop of the circuit is as shown in fig. 3, namely the +5V controller internal power supply supplies power to the controller circuit, and a loop of the +5V controller internal power supply, the current-limiting resistor R2, the PNP type triode Q1, the first resistor R1 and the third capacitor C3 is formed.
In the present embodiment, the implementation of the circuit entering self-test current limiting is realized by the voltage regulator device U1. Is stable in the channelsIn a closed circuit loop formed by the voltage device U1, the current limiting resistor R2 and the PNP transistor Q1, the kirchhoff theorem followed by the closed circuit can be used to obtain: voltage U across current limiting resistor R2R2The voltage drop (0.7V) between the emitter and the base of the PNP type triode Q1 is equal to the voltage U between two ends of the voltage stabilizing device U11Size, i.e. U1＝UR2+0.7。
Therefore, the current flowing through the current limiting resistor R2 is IR2＝(U1-0.7)/R2. When the PNP type triode Q1 works normally, the emitting electrode and the collecting electrode are conducted; at this time, the working circuit of the whole short-circuit protection circuit is the circuit shown in fig. 2, that is, the third capacitor C3 is regarded as an open circuit when the power supply is supplied by the controller internal power supply of +5V, the current flows through the current limiting resistor R2, the emitter of the PNP transistor Q1, the collector of the PNP transistor Q1 and the load R3, and finally, the circuit is grounded, so that the circuit in normal operation is formed. The base current of the PNP transistor Q1 may be temporarily ignored, as determined from the approximate direction of the loop current flow, and therefore, the emitter current of the PNP transistor Q1 may flow into the load circuit through the collector of the PNP transistor Q1. At this time, in the load circuit, the first capacitor C1 and the second capacitor C2 are both considered as open circuits. In the load circuit, the direct current voltage VCC supplies power to the load circuit, one end of the load R3 is connected with the direct current voltage VCC, and the other end is grounded to form a normal loop. The current flowing through the load R3 is IR3And has IR3Is equal to the collector current of the PNP transistor Q1.
When the load circuit causes the current I of the load circuit for some reasonR3＞IR2When the current is larger than the collector current of PNP transistor Q1 than the emitter current of PNP transistor Q1 (current-limiting current I)R2) When the PNP type triode Q1 is closed, namely the emitter and the collector of the PNP type triode are disconnected; at this time, the working loop of the whole short-circuit protection circuit is only the loop of the controller circuit, as shown in fig. 3, the current flowing direction of the loop current is roughly as shown in the figure, namely the current flowing direction of the loop current is +5V, the controller circuit is powered by the controller internal power supply, since the capacitor C3 is regarded as an open circuit due to the direct-current voltage, the current of the controller circuit flows through the current limiting resistor R2 and the PNP type circuitThe emitter of the transistor Q1, the base of the PNP transistor Q1, and the first resistor R1 are finally grounded, thereby forming a normal loop. The load circuit is powered by DC voltage VCC, and the load R3 is grounded to form a normal loop with IR3＝UVCCand/R3. When the current of the load circuit returns to normal, the whole short-circuit protection circuit returns to normal, that is, the working circuit shown in fig. 2 returns.
In this embodiment, the three-terminal regulator with model CJ431 is selected as the regulator device U1, and this embodiment is adopted in view of its high precision; however, in other embodiments, the selection of the present embodiment is not limited, and a device having a function similar to that of the voltage regulator may be selected to stabilize the voltage across the current limiting resistor R2, so as to stabilize the effect of the current limiting, i.e., the current flowing through the current limiting resistor R2; in other embodiments, the type of the voltage regulator device can be selected according to actual design requirements, for example, a common voltage regulator tube with two pins can be suitable for most application occasions with low precision requirements. In addition, the internal power supply of the controller of the present embodiment uses +5V, but in other embodiments, the value may not be limited to +5V, and may be selected according to the actual application and design requirements, such as +12V, +15, +24V, and the like, and is not limited to the value selection described in the present embodiment.
The short-circuit protection circuit designed in this embodiment can change the magnitude of the current-limiting current by changing the magnitude of the voltage to be stabilized by the voltage stabilizing device U1 and the magnitude of the current-limiting resistor R2. Meanwhile, in the circuit of the controller for controlling the external device applied to various fields, the short-circuit protection circuit for limiting the current is arranged, so that the function of protecting the controller is realized, and under the condition that the external environment influences the normal work of the load circuit, the connection between the controller circuit and the load circuit is disconnected, so that the controller circuit is not damaged, and the reliability of the controller circuit is improved. When the load circuit is recovered to normal, the circuit starts to work normally, and the PNP type triode Q1 is recovered to be in a conducting state. The design for limiting the output current of the collector terminal of the PNP type triode Q1 can effectively reduce the probability of accidents caused by the generation of large current; meanwhile, the circuit of the embodiment is simple to implement, low in cost and suitable for a plurality of controller circuits.
Example two:
in this embodiment, the switching device is a P-channel MOSFET, the voltage regulator device is a voltage regulator tube, and the rest of the circuit structure is designed as in the first embodiment. The first end of the switch device is a grid g of the P-channel MOSFET, the second end is a source s of the P-channel MOSFET, and the third end is a drain d of the P-channel MOSFET. The specific circuit structure is shown in fig. 4. In the embodiment, the circuit entering self-test current limiting mode is realized by a voltage stabilizing device U1. In a circuit loop formed by the voltage stabilizing device U1, the current limiting resistor R2 and the P-channel MOSFET, the conduction voltage drop U exists between the grid and the drain of the P-channel MOSFETGS(P-channel MOSFET of different types, with conduction drop UGSDifferent, such as 3V, 5V, etc.), the voltage regulator device U1 limits the voltage U across the current limiting resistor R2R2I.e. U1＝UR2+UGS. Therefore, the current I flowing through the current limiting resistor R2R2Is also defined as IR2＝(U1-UGS)/R2。
Similarly to the embodiment, when the controller circuit normally controls the load circuit to operate, the source s and the drain d of the P-channel MOSFET are turned on, and the current flows from the source s to the drain d of the P-channel MOSFET and then flows through the load circuit from the drain d. When the current of the load circuit is overlarge due to the abnormality of the load circuit, namely the current of the drain d of the P-channel MOSFET is overlarge, a maximum current, namely a current-limiting current is set at the source s due to the existence of the voltage stabilizing device U1 and the current-limiting resistor R2; therefore, the current of the source s of the P-channel MOSFET cannot be increased unconditionally due to the increase of the current of the drain d, when the current of the source s is increased to the current value of the current-limiting current, the source s and the drain d of the P-channel MOSFET close the conduction of the current, and the current flowing from the source s flows out of the grid g and returns to the controller circuit, so that the aim of disconnecting the current connection between the controller circuit and the load circuit is fulfilled.
In this embodiment, the internal power supply of the controller is +15V, and the voltage value selection of the internal power supply of the controller is a common technique in the prior art, and is not limited to the value selection described in this embodiment, so in other embodiments, the voltage value selection is not limited to this value, and the voltage values input in the controller circuit, such as +12V, +24V, etc., can be selected according to the actual application and design requirements. In addition, in this embodiment, since the P-channel MOSFET is used as the switching device, the regulator device U1 should not be a three-terminal regulator, and the selection of the regulator device needs to be determined according to the performance and actual design requirements of the P-channel MOSFET, for example, when the precision requirement on the regulator device U1 is not high, two common regulators of 10V may be selected; other voltage regulators may be used in other design requirements.
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it should be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; such modifications and substitutions do not depart from the spirit and scope of the present invention.
In short, the above description is only a preferred embodiment of the present invention, and all the equivalent changes and modifications made in accordance with the claims of the present invention should be covered by the scope of the present invention.
Claims (10)
1. A short-circuit protection circuit, characterized by:
the short-circuit protection circuit comprises a controller circuit and a load circuit;
the controller circuit comprises a current-limiting resistor, a switching device and a voltage stabilizing device, wherein the switching device is provided with three terminals comprising a first terminal, a second terminal and a third terminal;
the third end of the switching device is connected with the input end of the load circuit;
the voltage stabilizing device is coupled between the first end and the second end of the switching device;
the current limiting resistor is coupled between the second end of the switching device and the voltage stabilizing device;
the switching device is used for switching on/off the current flowing through the load circuit;
the voltage stabilizing device is used for limiting the maximum current flowing through the current limiting resistor and the switching device;
when the short-circuit protection circuit starts the current flowing through the load circuit at the switching device, the current flows through the third end from the second end of the switching device of the controller circuit and then flows to the load circuit;
when the short-circuit protection circuit turns off the current flowing through the load circuit at the switching device, the current flows through the first end from the second end of the switching device of the controller circuit and then returns to the controller circuit itself.
2. The short-circuit protection circuit of claim 1, wherein:
the load circuit comprises a load and a parallel capacitor bank coupled in parallel with the load, wherein the parallel capacitor bank comprises a first capacitor and a second capacitor, and the first capacitor is connected in parallel with the second capacitor;
and the common connection end of the load, the first capacitor and the second capacitor is connected with the third end of the switching device.
3. The short-circuit protection circuit of claim 2, wherein:
the load, the first capacitor, the second capacitor and a common connecting end of a third end of the switching device are connected to a direct-current power supply;
and the other common connection end of the load, the first capacitor and the second capacitor is grounded.
4. The short-circuit protection circuit of claim 1, wherein:
the controller circuit further comprises a first resistor, a common connecting end where the first end of the switching device and the voltage stabilizing device are connected is connected with one end of the first resistor, and the other end of the first resistor is grounded.
5. The short-circuit protection circuit of claim 1, wherein:
the controller circuit further comprises a third capacitor, a common connecting end of the voltage stabilizing device and the current limiting resistor is connected with one end of the third capacitor, and the other end of the third capacitor is grounded.
6. The short-circuit protection circuit of claim 5, wherein:
the controller circuit further comprises a controller internal power supply, and the controller internal power supply inputs power supply voltage into the controller circuit through the voltage stabilizing device, the current limiting resistor and the common connecting end of the third capacitor.
7. The short-circuit protection circuit according to any one of claims 1 to 6, wherein:
the switching device is a PNP type triode.
8. The short-circuit protection circuit of claim 7, wherein:
the voltage stabilizing device is a three-terminal voltage stabilizer.
9. The short-circuit protection circuit according to any one of claims 1 to 6, wherein:
the switching device is a P-channel MOSFET.
10. The short-circuit protection circuit of claim 1, wherein:
the voltage stabilizer is a voltage stabilizing tube.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201921412464.8U CN210111587U (en) | 2019-08-28 | 2019-08-28 | Short-circuit protection circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201921412464.8U CN210111587U (en) | 2019-08-28 | 2019-08-28 | Short-circuit protection circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN210111587U true CN210111587U (en) | 2020-02-21 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201921412464.8U Active CN210111587U (en) | 2019-08-28 | 2019-08-28 | Short-circuit protection circuit |
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| Country | Link |
|---|---|
| CN (1) | CN210111587U (en) |
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2019
- 2019-08-28 CN CN201921412464.8U patent/CN210111587U/en active Active
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| CB03 | Change of inventor or designer information |
Inventor after: Li Wenjie Inventor after: Ge Ziting Inventor after: Cao Baifeng Inventor after: Zhang Bin Inventor before: Li Wenjie Inventor before: Ge Ziting Inventor before: Cao Baifeng Inventor before: Zhang Bin |