CN112186722B - Circuit with current limiting locking function - Google Patents
Circuit with current limiting locking function Download PDFInfo
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- CN112186722B CN112186722B CN202011084766.4A CN202011084766A CN112186722B CN 112186722 B CN112186722 B CN 112186722B CN 202011084766 A CN202011084766 A CN 202011084766A CN 112186722 B CN112186722 B CN 112186722B
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H9/00—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection
- H02H9/02—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection responsive to excess current
Abstract
The invention provides a circuit with a current-limited locking function, which comprises: the current detection circuit, the current control circuit, the power supply switch control circuit and the overcurrent locking circuit; the current detection circuit is used for detecting the current value in the power supply loop, converting the current signal into a voltage signal and feeding back the voltage signal to the current control circuit; the current control circuit is used for converting a voltage signal provided by the current detection circuit into a switching signal, wherein the switching signal is off when the current is normal, and the switching signal is on when the current value exceeds a limit value, and feeds the switching signal back to the power supply switch control circuit; the power supply switch control circuit is used for realizing the switch control of the power supply loop by the switch signal provided by the current control circuit, opening the power supply loop when the switch signal is off, and closing the power supply loop when the switch signal is on to cut off the power supply output; the invention closes the power supply loop when realizing current limiting.
Description
Technical Field
The invention relates to the technical field of electronic circuits, in particular to a circuit with a current-limiting locking function.
Background
With the development of electronic technology, the power supply device pays more and more attention to safety performance, wherein the current limiting technology is the core technology for ensuring the safety performance. The existing current limiting technology has two modes: flow-limiting and flow-intercepting. The current-limiting circuit has the technical scheme that a constant voltage is applied to a current-limiting resistor to limit the maximum output power, and the current-limiting circuit has the advantages that the circuit is simple, has the defect that the maximum limited power can be always output when a load is short-circuited, and cannot be turned off; the technical mode of the cut-off type circuit is that the current of a loop is monitored by using a sampling resistor, and the power supply output is closed when the current exceeds the set maximum current. Today, miniaturization of various power supply devices is increasingly emphasized, and a simple circuit capable of realizing current limiting shutdown is required.
Disclosure of Invention
The invention aims to overcome the defects in the prior art, provides a circuit with a current-limiting locking function, closes a power supply loop when current limiting is realized, has simple design, makes up the defects of the two circuits, and inherits the advantages of the two circuits.
The embodiment of the invention adopts the technical scheme that:
a circuit with current limited locking, comprising: the current detection circuit, the current control circuit, the power supply switch control circuit and the overcurrent locking circuit;
the current detection circuit is used for detecting the current value in the power supply loop, converting the current signal into a voltage signal and feeding back the voltage signal to the current control circuit;
the current control circuit is used for converting a voltage signal provided by the current detection circuit into a switching signal, wherein the switching signal is off when the current is normal, and the switching signal is on when the current value exceeds a limit value, and feeds the switching signal back to the power supply switch control circuit;
the power supply switch control circuit is used for realizing the switch control of the power supply loop by the switch signal provided by the current control circuit, opening the power supply loop when the switch signal is off, and closing the power supply loop when the switch signal is on to cut off the power supply output;
the overcurrent locking circuit is used for keeping a switching signal of the current control circuit still on when the current value is reduced to zero after the power supply circuit is closed when the overcurrent fault is not cancelled, so that the closed state of the power supply circuit is locked.
Further, the air conditioner is provided with a fan,
the current detection circuit comprises resistors R3 and R4 and a current monitoring chip U1;
the current control circuit comprises a diode D1, a resistor R7, a resistor R8, a capacitor C7 and an NMOS tube Q3;
the power supply switch control circuit comprises a capacitor C4, resistors R9, R10 and an NMOS tube Q4;
the overcurrent locking circuit comprises a capacitor C3, resistors R5, R6 and a PNP triode Q2;
two detection pins of the current monitoring chip U1 are respectively connected with two ends of a resistor R3, one end of the resistor R3 is connected with a positive voltage line, and the other end of the resistor R3 is connected with an output voltage line; the output end of the current monitoring chip U1 is connected with one end of a resistor R4 and the anode of a diode D1, and the other end of the resistor R4 is grounded;
the cathode of the diode D1 is connected with one end of a resistor R7, the other end of the resistor R7 is connected with the collector of the triode Q2, one end of the resistor R8, one end of a capacitor C7 and the grid of an NMOS tube Q3; the other end of the resistor R8, the other end of the capacitor C7 and the source electrode of the NMOS transistor Q3 are grounded;
the drain electrode of the NMOS tube Q3 is connected with the base electrode of the triode Q2, one end of the resistors R9 and R10, one end of the capacitor C4 and the grid electrode of the NMOS tube Q4; the other end of the resistor R9 and the other end of the capacitor C4 are connected with an output voltage wire; the other end of the resistor R10 and the source electrode of the NMOS tube Q4 are grounded;
one end of the resistor R6 is connected with an output voltage wire, and the other end is connected with one end of the capacitor C3, one end of the resistor R5 and an emitter of the triode Q2; the other end of the capacitor C3 and the other end of the resistor R5 are grounded.
Furthermore, the circuit with the current-limiting locking function also comprises a working indication circuit;
the work indication circuit comprises an LED-1, an LED-2, resistors R1, R2, an NMOS tube Q1 and a capacitor C6; the grid electrode of the NMOS tube Q1 is connected with the output end of the current monitoring chip U1 and is grounded through a capacitor C6; the drain electrode of the NMOS tube Q1 is connected with the cathode of the LED-2 through a resistor R2, and the anode of the LED-2 is connected with a positive voltage line; the source electrode of the NMOS tube Q1 is grounded; the anode of LED-1 is connected to the positive voltage line, and the cathode is connected to ground through resistor R1.
Furthermore, the circuit with the current-limiting locking function also comprises an output voltage stabilizing circuit;
the output voltage stabilizing circuit comprises a capacitor C5, an inductor L1 and a voltage stabilizing diode D2; one end of the inductor L1 and one end of the capacitor C5 are connected with an output voltage line, and the other end of the inductor L1 is connected with a positive output end B +; the other end of the capacitor C5 is connected with the drain electrode of the NMOS tube Q4; the cathode of the voltage-stabilizing diode D2 is connected with the positive output end B +, and the anode is connected with the drain electrode and the negative output end B-of the NMOS tube Q4;
further, R6/R5 equals R9/R10.
The invention has the advantages that:
1. the invention provides a solution of current limiting function and power supply circuit turn-off locking function after current limiting;
2. the circuit is simple and easy to use, the set current value is very flexible, the reliability and the stability are high, and the circuit cost is lower than that of other circuits.
Drawings
Fig. 1 is a schematic circuit diagram of an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
The embodiment of the invention provides a circuit with a current-limiting locking function, which comprises: the current detection circuit, the current control circuit, the power supply switch control circuit and the overcurrent locking circuit;
the current detection circuit is used for detecting the current value in the power supply loop, converting the current signal into a voltage signal and feeding back the voltage signal to the current control circuit;
the current control circuit is used for converting a voltage signal provided by the current detection circuit into a switching signal, wherein the switching signal is off when the current is normal, and the switching signal is on when the current value exceeds a limit value, and feeds the switching signal back to the power supply switch control circuit;
the power supply switch control circuit is used for realizing the switch control of the power supply loop by the switch signal provided by the current control circuit, opening the power supply loop when the switch signal is off, and closing the power supply loop when the switch signal is on to cut off the power supply output;
the overcurrent locking circuit is used for keeping a switching signal of the current control circuit still on when the current value is reduced to zero after the power supply circuit is closed when the overcurrent fault is not cancelled, so that the closed state of the power supply circuit is locked.
The circuit with the current-limiting locking function can also comprise an AC-DC conversion circuit, a work indicating circuit and an output voltage stabilizing circuit;
as shown in fig. 1, the AC-DC conversion circuit includes an AC-DC conversion module U2, fuses F1, F2, filter capacitors C1, C2; the live wire end of the AC-DC conversion module U2 is used for connecting a live wire L through a fuse F2, and the zero line end is used for connecting a zero line; the positive output end of the AC-DC conversion module U2 is connected with a positive voltage wire, and the grounding end is grounded; the fuse F1 is connected on the positive voltage line; one end of each of the filter capacitors C1 and C2 is connected with a positive voltage line, and the other end of each of the filter capacitors is grounded;
the current detection circuit comprises resistors R3 and R4 and a current monitoring chip U1, wherein ZXCT1009 is adopted in U1;
the current control circuit comprises a diode D1, a resistor R7, a resistor R8, a capacitor C7 and an NMOS tube Q3;
the power supply switch control circuit comprises a capacitor C4, resistors R9, R10 and an NMOS tube Q4;
the overcurrent locking circuit comprises a capacitor C3, resistors R5, R6 and a PNP triode Q2;
two detection pins of the current monitoring chip U1 are respectively connected with two ends of a resistor R3, one end of the resistor R3 is connected with a positive voltage line, and the other end of the resistor R3 is connected with an output voltage line; the output end of the current monitoring chip U1 is connected with one end of a resistor R4 and the anode of a diode D1, and the other end of the resistor R4 is grounded;
the cathode of the diode D1 is connected with one end of a resistor R7, the other end of the resistor R7 is connected with the collector of the triode Q2, one end of the resistor R8, one end of a capacitor C7 and the grid of an NMOS tube Q3; the other end of the resistor R8, the other end of the capacitor C7 and the source electrode of the NMOS transistor Q3 are grounded;
the drain electrode of the NMOS tube Q3 is connected with the base electrode of the triode Q2, one end of the resistors R9 and R10, one end of the capacitor C4 and the grid electrode of the NMOS tube Q4; the other end of the resistor R9 and the other end of the capacitor C4 are connected with an output voltage wire; the other end of the resistor R10 and the source electrode of the NMOS tube Q4 are grounded; the output voltage line and the drain electrode of the NMOS tube Q4 are used for being connected with an output voltage stabilizing circuit;
one end of the resistor R6 is connected with an output voltage wire, and the other end is connected with one end of the capacitor C3, one end of the resistor R5 and an emitter of the triode Q2; the other end of the capacitor C3 and the other end of the resistor R5 are grounded;
the work indication circuit comprises an LED-1, an LED-2, resistors R1, R2, an NMOS tube Q1 and a capacitor C6; the grid electrode of the NMOS tube Q1 is connected with the output end of the current monitoring chip U1 and is grounded through a capacitor C6; the drain electrode of the NMOS tube Q1 is connected with the cathode of the LED-2 through a resistor R2, and the anode of the LED-2 is connected with a positive voltage line; the source electrode of the NMOS tube Q1 is grounded; the anode of the LED-1 is connected with a positive voltage line, and the cathode is connected with the ground through a resistor R1;
the output voltage stabilizing circuit comprises a capacitor C5, an inductor L1 and a voltage stabilizing diode D2; one end of the inductor L1 and one end of the capacitor C5 are connected with an output voltage line, and the other end of the inductor L1 is connected with a positive output end B +; the other end of the capacitor C5 is connected with the drain electrode of the NMOS tube Q4; the cathode of the voltage-stabilizing diode D2 is connected with the positive output end B +, and the anode is connected with the drain electrode and the negative output end B-of the NMOS tube Q4;
the AC-DC conversion module U2 converts alternating current into direct current for supplying power to a load, and the F1 and F2 fuses are fused when an overcurrent fault occurs, so that the power output is closed;
r3 is a sampling resistor, the current signal is converted into a voltage signal, the voltage at two ends of the sampling resistor R3 is converted into the current signal in proportion under the action of U1 and is applied to two ends of R4, the voltage at two ends of R4 is increased along with the increase of the current on a power supply loop, and R7 and R8 divide the voltage of R4; when the voltage across R8 exceeds V of Q3gsTurn on Q3, pull the voltage across R10 down to ground, i.e., V of Q4gsAnd falls to 0, thereby turning off Q4 and achieving the power supply loop off. By change of resistance of R4 and V of Q3gsThe maximum current value that can be output on the power supply circuit is controlled by the selection of the threshold value. When the power supply loop works normally, R6/R5 is selected to be equal to R9/R10, and V of Q2 at the momentbc0, Q2 is off, and when the current is over-limit, Q3 opens pulling the voltage across R10 low, causing VbcThe threshold of Q2 is exceeded, turning on Q2. When the power supply loop is turned off, the current value on the loop returns to zero, the voltage at two ends of R8 is reduced, but at the moment, due to the opening of Q2, the voltage is pulled up again at two ends of R8, so that Q3 keeps an open state, the opening of Q3 enables Q4 to be turned off and Q2 to be turned on, a closed loop is formed, and the stable state of circuit locking is realized.
Finally, it should be noted that the above embodiments are only for illustrating the technical solutions of the present invention and not for limiting, and although the present invention has been described in detail with reference to examples, it should be understood by those skilled in the art that modifications or equivalent substitutions may be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, which should be covered by the claims of the present invention.
Claims (4)
1. A circuit with current limited locking, comprising: the current detection circuit, the current control circuit, the power supply switch control circuit and the overcurrent locking circuit;
the current detection circuit is used for detecting the current value in the power supply loop, converting the current signal into a voltage signal and feeding back the voltage signal to the current control circuit;
the current control circuit is used for converting a voltage signal provided by the current detection circuit into a switching signal, wherein the switching signal is off when the current is normal, and the switching signal is on when the current value exceeds a limit value, and feeds the switching signal back to the power supply switch control circuit;
the power supply switch control circuit is used for realizing the switch control of the power supply loop by the switch signal provided by the current control circuit, opening the power supply loop when the switch signal is off, and closing the power supply loop when the switch signal is on to cut off the power supply output;
the overcurrent locking circuit is used for keeping a switching signal of the current control circuit still on when the current value is reduced to zero after the power supply circuit is closed when the overcurrent fault is not cancelled, so that the closed state of the power supply circuit is locked;
the current detection circuit comprises resistors R3 and R4 and a current monitoring chip U1;
the current control circuit comprises a diode D1, a resistor R7, a resistor R8, a capacitor C7 and an NMOS tube Q3;
the power supply switch control circuit comprises a capacitor C4, resistors R9, R10 and an NMOS tube Q4;
the overcurrent locking circuit comprises a capacitor C3, resistors R5, R6 and a PNP triode Q2;
two detection pins of the current monitoring chip U1 are respectively connected with two ends of a resistor R3, one end of the resistor R3 is connected with a positive voltage line, and the other end of the resistor R3 is connected with an output voltage line; the output end of the current monitoring chip U1 is connected with one end of a resistor R4 and the anode of a diode D1, and the other end of the resistor R4 is grounded;
the cathode of the diode D1 is connected with one end of a resistor R7, the other end of the resistor R7 is connected with the collector of the triode Q2, one end of the resistor R8, one end of a capacitor C7 and the grid of an NMOS tube Q3; the other end of the resistor R8, the other end of the capacitor C7 and the source electrode of the NMOS transistor Q3 are grounded;
the drain electrode of the NMOS tube Q3 is connected with the base electrode of the triode Q2, one end of the resistors R9 and R10, one end of the capacitor C4 and the grid electrode of the NMOS tube Q4; the other end of the resistor R9 and the other end of the capacitor C4 are connected with an output voltage wire; the other end of the resistor R10 and the source electrode of the NMOS tube Q4 are grounded;
one end of the resistor R6 is connected with an output voltage wire, and the other end is connected with one end of the capacitor C3, one end of the resistor R5 and an emitter of the triode Q2; the other end of the capacitor C3 and the other end of the resistor R5 are grounded.
2. The circuit with current-limiting locking function of claim 1,
the device also comprises a work indication circuit;
the work indication circuit comprises an LED-1, an LED-2, resistors R1, R2, an NMOS tube Q1 and a capacitor C6; the grid electrode of the NMOS tube Q1 is connected with the output end of the current monitoring chip U1 and is grounded through a capacitor C6; the drain electrode of the NMOS tube Q1 is connected with the cathode of the LED-2 through a resistor R2, and the anode of the LED-2 is connected with a positive voltage line; the source electrode of the NMOS tube Q1 is grounded; the anode of LED-1 is connected to the positive voltage line, and the cathode is connected to ground through resistor R1.
3. The circuit with current-limiting locking function of claim 1,
the output voltage stabilizing circuit is also included;
the output voltage stabilizing circuit comprises a capacitor C5, an inductor L1 and a voltage stabilizing diode D2; one end of the inductor L1 and one end of the capacitor C5 are connected with an output voltage line, and the other end of the inductor L1 is connected with a positive output end B +; the other end of the capacitor C5 is connected with the drain electrode of the NMOS tube Q4; the cathode of the voltage-stabilizing diode D2 is connected with the positive output end B +, and the anode is connected with the drain of the NMOS tube Q4 and the negative output end B-.
4. The circuit with current-limiting locking function of claim 1,
R6/R5 equals R9/R10.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011084766.4A CN112186722B (en) | 2020-10-12 | 2020-10-12 | Circuit with current limiting locking function |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011084766.4A CN112186722B (en) | 2020-10-12 | 2020-10-12 | Circuit with current limiting locking function |
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| CN112186722A CN112186722A (en) | 2021-01-05 |
| CN112186722B true CN112186722B (en) | 2021-09-14 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN210468772U (en) * | 2019-08-29 | 2020-05-05 | 浙江中自机电控制技术有限公司 | Overcurrent protection circuit for multi-arm electromagnet drive |
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2020
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| JPH10271660A (en) * | 1997-03-26 | 1998-10-09 | Mitsubishi Electric Corp | Overcurrent detector |
| CN101577419A (en) * | 2009-06-22 | 2009-11-11 | 安徽摆客动力技术有限公司 | Selflocking direct current supply short circuit protection circuit |
| CN102035168A (en) * | 2009-09-30 | 2011-04-27 | 富士通天株式会社 | Overcurrent protection circuit and in-vehicle display device |
| CN101777760A (en) * | 2010-03-05 | 2010-07-14 | 厦门大学 | Laser power supply overcurrent protection circuit with locking function |
| CN102938797A (en) * | 2012-11-05 | 2013-02-20 | Tcl通讯（宁波）有限公司 | Current detection and control device for mobile terminal |
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