CN113991600A - Overcurrent protection circuit with automatic latching function - Google Patents
Overcurrent protection circuit with automatic latching function Download PDFInfo
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- CN113991600A CN113991600A CN202111206280.8A CN202111206280A CN113991600A CN 113991600 A CN113991600 A CN 113991600A CN 202111206280 A CN202111206280 A CN 202111206280A CN 113991600 A CN113991600 A CN 113991600A
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- 238000001514 detection method Methods 0.000 claims abstract description 48
- 230000005669 field effect Effects 0.000 claims description 44
- 239000003990 capacitor Substances 0.000 claims description 6
- 238000001914 filtration Methods 0.000 claims description 5
- 230000004044 response Effects 0.000 abstract description 6
- 230000035945 sensitivity Effects 0.000 abstract description 2
- 230000008859 change Effects 0.000 description 3
- 238000000034 method Methods 0.000 description 3
- 238000010586 diagram Methods 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 206010000369 Accident Diseases 0.000 description 1
- 230000002159 abnormal effect Effects 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000035484 reaction time Effects 0.000 description 1
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- 238000000926 separation method Methods 0.000 description 1
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/08—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to excess current
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/02—Details
- H02H3/05—Details with means for increasing reliability, e.g. redundancy arrangements
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Abstract
The invention discloses an overcurrent protection circuit with an automatic latch function, which comprises a feedback control module, a main control switch module and a current detection module which are sequentially connected, wherein a filter unit is connected with a power supply to output electric energy to the main control switch module and provide stable voltage for a load; the intelligent triggering of the overcurrent signal is realized by adding the detection resistor to the PN junction attribute of the base stage and the emitter of the triode, the response time is short, and the reliability is high. The current detection sensitivity and the adjustable overcurrent threshold value are realized through the detection resistor.
Description
Technical Field
The invention relates to the field of overcurrent protection, in particular to an overcurrent protection circuit with an automatic latch function.
Background
Overcurrent protection is a protection method in which a protection device is operated when a current exceeds a predetermined maximum value. When the current flowing through the protected element exceeds a preset value, the protection device is started to trip the circuit breaker or give an alarm signal. If no overcurrent protection device is arranged, once the current is too large due to short circuit or abnormal components in some circuits, the components are easy to burn out, especially in some circuits sensitive to current change, fire accidents even due to the too large current are caused seriously, and therefore the arrangement of the overcurrent protection circuit is necessary. The existing overcurrent protection device is relatively accurate in response to the change of large current, but relatively small overcurrent is relatively slow in response or even cannot be detected, the phenomenon can easily cause that the overcurrent protection device can only act under the condition of short circuit or large current change, and if the overcurrent protection device needs to act after the current rises to be high, some components sensitive to the current reaction can be broken down and burned out in the current high-rise process. Meanwhile, the existing overcurrent protection circuit has an unreliable separation phenomenon in the reuse process, namely, after overcurrent protection responds, the control switch is not completely separated from the load circuit. There is therefore a need for an overcurrent protection circuit that is responsive and latches the control to ensure complete disconnection.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: the overcurrent protection circuit is simple and reliable to use, low in cost, low in time delay, adjustable in overcurrent threshold value and capable of quickly cutting off a load power supply and automatically latching when an overcurrent fault occurs.
The technical scheme adopted by the invention for solving the technical problems is as follows: an overcurrent protection circuit with an automatic latching function comprises a feedback control module, a main control switch module and a current detection module which are connected in sequence, the filtering unit is connected with the power supply and used for filtering noise of the input power supply and outputting the filtered electric energy to the main control switch module, and provides stable voltage for the load, the feedback control module is used for receiving the signal of the current detection module and controlling the on-off of the main control switch module, the main control switch module is connected with the power supply and supplies power to the load circuit where the current detection module is positioned, the main control switch module controls the on-off of the power supply, the current detection module is used for detecting the current of the load circuit and transmitting a signal to the feedback control module, and a latch unit is also arranged between the feedback control module and the main control switch and used for latching the control signal output to the feedback control module by the current detection module.
Furthermore, the power supply comprises a power line connected with the positive electrode and a grounding line connected with the negative electrode, the main control switch comprises a first field effect tube and a second field effect tube, the source electrode of the first field effect tube is connected with the power line, the grid electrode of the first field effect tube is connected with one end of a first resistor and one end of a second resistor, the other end of the first resistor is connected with the power supply, the other end of the second resistor is connected with the drain electrode of the second field effect tube, the source electrode of the second field effect tube is connected with the grounding line, the grid electrode of the second field effect tube is connected with the feedback control module, and the drain electrode of the first field effect tube is connected with the current detection module.
Furthermore, the feedback control module comprises a first triode, a collector of the first triode is connected with a grid electrode of the second field effect transistor, an emitter of the first triode is connected with a grounding wire, a collector of the first triode is further connected with a power line through a third resistor, and a base of the first triode is connected with the current detection module through a fourth resistor.
Furthermore, the current detection module comprises a detection resistor and a second triode, wherein an emitting electrode of the second triode is connected with one end of the detection resistor and a drain electrode of the first field effect transistor, a base electrode of the second triode is connected with the other end of the detection resistor, the other end of the detection resistor is also connected with a load, a collector electrode of the second triode is connected with one end of a fifth resistor, one end of the fifth resistor is also connected with a fourth resistor, and the other end of the fifth resistor is connected with a grounding wire.
Furthermore, the latch unit comprises a third triode and a fourth triode, wherein the base of the third triode is connected with the collector of the first triode and the grid of the second field effect transistor, the emitter of the third triode is connected with the power line through a sixth resistor, the collector of the third triode is connected with the ground wire through a seventh resistor, the base of the fourth triode is connected with the collector of the third triode, the emitter of the fourth triode is connected with the ground wire, and the collector of the fourth triode is connected with the base of the third triode.
Furthermore, the filter unit comprises a filter inductor, one end of the filter inductor is connected with a power supply, the other end of the filter inductor is connected with a source electrode of the first field effect transistor, one end of the filter inductor is connected with a ground wire through a first capacitor, and the other end of the filter inductor is connected with the ground wire through a second capacitor.
The invention has the advantages that the quick response is realized through fewer low-cost discrete components, the overcurrent protection and self-locking functions with adjustable overcurrent threshold are realized, and the invention can be applied to different current requirements of different occasions. The intelligent triggering of the overcurrent signal is realized by adding the detection resistor to the PN junction attribute of the base stage and the emitter of the triode, the scheme of a comparator and a microcontroller with higher cost is replaced, and the intelligent triggering device has great advantages in cost, response time and reliability. The current detection sensitivity and the adjustability of the magnitude of the overcurrent threshold are realized through the detection resistor, and a comparator and MCU scheme which needs an additional reference voltage source and a reference current source, is poor in adjustability and is limited in application scene is replaced. Through increasing the self-locking module, can feed back the signal that overflows that the current detection module detected to feedback control module, transmit then to the self-locking module and lock the main switch in the shutoff state that overflows to guarantee the reliable disconnection of main control switch module, thoroughly break off load circuit and power part, effectively improve security and reliability, avoid the too big reverse action of electric current in the load circuit to the power, lead to the occurence of failure.
Drawings
FIG. 1 is a functional block diagram of the present invention;
fig. 2 is a schematic diagram of the inventive circuit connection.
Detailed Description
The invention is described in further detail below with reference to the accompanying examples.
The utility model provides an overcurrent protection circuit with automatic latching function, is including the feedback control module, master control switch module and the current detection module that connect gradually, and the feedback control module is used for receiving current detection module's signal and controls the break-make of master control switch module, and master control switch module links to each other with the power and supplies power for the load circuit at current detection module place, just the break-make of master control switch module control power, current detection module are used for detecting the electric current of load circuit and with signal transmission to feedback control module, still are provided with the latch unit between feedback control module and the master control switch, and the latch unit is used for latching the control signal that current detection module exported to feedback control module.
The power supply comprises a power line connected with a positive electrode and a ground wire connected with a negative electrode, the main control switch comprises a first field effect tube and a second field effect tube M2, the source electrode of the first field effect tube M1 is connected with the power line, the grid electrode of the first field effect tube M1 is connected with one end of a first resistor R1 and one end of a second resistor R2, the other end of the first resistor R1 is connected with the power supply, the other end of the second resistor R2 is connected with the drain electrode of the second field effect tube M2, the source electrode of the second field effect tube M2 is connected with the ground wire, the grid electrode of the second field effect tube M2 is connected with the feedback control module, and the drain electrode of the first field effect tube M1 is connected with one end of the check resistor of the current detection module.
The feedback control module comprises a first triode Q1, wherein the collector of the first triode Q1 is connected with the gate of a second field effect transistor M2, the emitter of the first triode Q1 is connected with the ground wire, the collector of the first triode Q1 is also connected with the power line through a third resistor R3, and the base of the first triode Q1 is connected with the collector of the second triode Q2 of the current detection module through a fourth resistor R4.
The current detection module comprises a detection resistor R6 and a second triode Q2, wherein an emitter of the second triode Q2 is connected with one end of the detection resistor R6 and a drain of the first field-effect transistor M1, a base of the second triode Q2 is connected with the other end of the detection resistor R6, the other end of the detection resistor R6 is further connected with a load, a collector of the second triode Q2 is connected with one end of a fifth resistor R5, one end of the fifth resistor R5 is further connected with a fourth resistor R4, and the other end of the fifth resistor R5 is connected with a ground wire.
The latch unit comprises a third triode Q3 and a fourth triode Q4, wherein the base of the third triode Q3 is connected with the collector of the first triode Q1 and the grid of the second field effect transistor M2, the emitter of the third triode Q3 is connected with the power line through a sixth resistor R6, the collector of the third triode Q3 is connected with the ground line through a seventh resistor R7, the base of the fourth triode Q4 is connected with the collector of the third triode Q3, the emitter of the fourth triode Q4 is connected with the ground line, and the collector of the fourth triode Q4 is connected with the base of the third triode Q3.
The filter unit provided by the invention comprises a filter inductor L1, wherein one end of a filter inductor L1 is connected with a power supply V1, the other end of the filter inductor L1 is connected with the source electrode of a first field effect transistor M1, one end of a filter inductor L1 is connected with a ground wire through a first capacitor C1, and the other end of the filter inductor L1 is connected with the ground wire through a second capacitor C2; the power supply voltage can be optimized stably by the arrangement of the filtering unit, the quality of the power supply is effectively improved, the voltage output is more stable, the fluctuation of current in a load circuit connected with the main control circuit under the normal working condition is reduced, and the reliability of the current detection module is improved.
The working principle of the invention is as follows: at the time of an initial normal working state, the current of the load circuit is normal, the voltage of the detection resistor R6 is small, so that the second diode is in a cut-off state, at this time, the first triode Q1 is directly connected with the ground wire through the fourth resistor R4 and the fifth resistor R5, at this time, the first triode Q1 is also in a cut-off state, meanwhile, the base of the third triode Q3 is connected with the power wire through the third resistor R3, the emitter is connected with the power wire through the sixth resistor R6, so that the third triode Q3 is in a cut-off state, and the base of the fourth resistor R4 is connected with the ground wire through the seventh resistor R7, and is also in a cut-off state.
In an initial state, the voltage of the grid electrode of the second field effect transistor M2 connected with the power line through the third resistor R3 is pulled up to the power voltage, the grid-source voltage of the second field effect transistor M2 is greater than the grid-source threshold voltage, and therefore the drain electrode and the source electrode of the second field effect transistor M2 are conducted; meanwhile, the first resistor R1 and the second resistor R2 perform voltage division, after the voltage division, the voltage of the first resistor R1 acts on the grid electrode of the first field-effect tube M1 and is larger than the grid electrode threshold voltage of the first field-effect tube M1, so that the drain electrode and the source electrode of the first field-effect tube M1 are conducted, and the power line outputs the voltage outwards through the source electrode and the drain electrode of the first field-effect tube M1.
When a short circuit to the ground or an equipment fault occurs in a load circuit, namely the current in the load circuit is rapidly increased, the voltage drop at two ends of the detection resistor R6 is increased, the voltage applied to the emitter and the base of the second triode Q2 is increased, when the voltage drop is larger than 0.7V, the second triode Q2 enters a saturation region for conduction after reaction time, and the voltage at two ends of the fifth resistor R5 is approximate to the power supply voltage; at this time, the base voltage of the first transistor Q1 connected to the fifth resistor R5 through the fourth resistor R4 increases, Vbe of the first transistor Q1 reaches 0.7V, the first transistor Q1 enters a saturation region, the first transistor Q1 is turned on, and the gate of the second fet M2 is pulled down to ground, so that the second fet M2 enters a cut-off region. When the first triode Q1 is turned on, the latch unit operates, that is, the base of the third triode Q3 is connected to the ground line, the voltage is pulled down to the ground, at this time, the emitter of the third triode Q3 is connected to the power line through the sixth resistor R6, so that the third triode Q3 enters the saturation region to be turned on, and simultaneously, the base voltage of the fourth triode Q4 is increased due to the partial voltage of the sixth resistor R6 and the seventh resistor R7, so that the fourth triode Q4 is driven to be turned on. When the second field effect transistor M2 enters a cut-off state, the first field effect transistor M1 also enters a cut-off state, and at this time, the current load in the load line is rapidly reduced to zero, the voltage drop at two ends of the detection resistor R6 is reduced, so that the second triode Q2 enters a cut-off state, the base of the first triode Q1 is further pulled down to the ground through the fourth resistor R4 and the fifth resistor R5, and the first triode Q1 enters a cut-off state; due to the response of the latch unit, at this time, the base of the third transistor Q3 is grounded through the collector and the emitter of the fourth transistor Q4, and the emitter of the third transistor Q3 is connected to the power line through the sixth resistor R6, thereby ensuring the conduction of the third transistor Q3. Meanwhile, the conduction of the fourth triode Q4 is ensured due to the conduction of the third triode Q3, namely, the automatic latching of signals is realized through interaction, so that the connection of the grid of the second field-effect tube M2 and the grounding wire is reliably ensured, the first field-effect tube M1 is reliably disconnected, and the overcurrent protection is realized.
The above-mentioned embodiments are only preferred embodiments of the present invention, and the description thereof is more specific and detailed, but not to be construed as limiting the scope of the present invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention.
Claims (6)
1. An over-current protection circuit with an automatic latching function is characterized by comprising a feedback control module, a main control switch module and a current detection module which are connected in sequence, the filtering unit is connected with the power supply and used for filtering noise of the input power supply and outputting the filtered electric energy to the main control switch module, and provides stable voltage for the load, the feedback control module is used for receiving the signal of the current detection module and controlling the on-off of the main control switch module, the main control switch module is connected with the power supply and supplies power to the load circuit where the current detection module is positioned, the main control switch module controls the on-off of the power supply, the current detection module is used for detecting the current of the load circuit and transmitting a signal to the feedback control module, and a latch unit is also arranged between the feedback control module and the main control switch and used for latching the control signal output to the feedback control module by the current detection module.
2. The overcurrent protection circuit with the automatic latch function as claimed in claim 1, wherein the power supply includes a power line connected to the positive electrode and a ground line connected to the negative electrode, the main control switch includes a first field effect transistor and a second field effect transistor, the source of the first field effect transistor is connected to the power line, the gate of the first field effect transistor is connected to one end of a first resistor and one end of a second resistor, the other end of the first resistor is connected to the power supply, the other end of the second resistor is connected to the drain of the second field effect transistor, the source of the second field effect transistor is connected to the ground line, the gate of the second field effect transistor is connected to the feedback control module, and the drain of the first field effect transistor is connected to the current detection module.
3. The overcurrent protection circuit with an automatic latch function as claimed in claim 2, wherein the feedback control module comprises a first transistor, a collector of the first transistor is connected to a gate of the second fet, an emitter of the first transistor is connected to a ground line, the collector of the first transistor is further connected to a power line through a third resistor, and a base of the first transistor is connected to the current detection module through a fourth resistor.
4. The overcurrent protection circuit with the automatic latching function as claimed in claim 3, wherein the current detection module comprises a detection resistor and a second triode, an emitter of the second triode is connected to one end of the detection resistor and a drain of the first field effect transistor, a base of the second triode is connected to the other end of the detection resistor, the other end of the detection resistor is further connected to a load, a collector of the second triode is connected to one end of a fifth resistor, one end of the fifth resistor is further connected to a fourth resistor, and the other end of the fifth resistor is connected to a ground line.
5. The overcurrent protection circuit with an automatic latch function as recited in claim 3, wherein the latch unit includes a third transistor and a fourth transistor, a base of the third transistor is connected to a collector of the first transistor and a gate of the second fet, an emitter of the third transistor is connected to the power line through a sixth resistor, a collector of the third transistor is connected to the ground line through a seventh resistor, a base of the fourth transistor is connected to a collector of the third transistor, an emitter of the fourth transistor is connected to the ground line, and a collector of the fourth transistor is connected to a base of the third transistor.
6. The overcurrent protection circuit with the automatic latch function as claimed in claim 2, wherein the filter unit includes a filter inductor, one end of the filter inductor is connected to a power supply, the other end of the filter inductor is connected to the source of the first fet, one end of the filter inductor is connected to the ground line through a first capacitor, and the other end of the filter inductor is connected to the ground line through a second capacitor.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111206280.8A CN113991600A (en) | 2021-10-16 | 2021-10-16 | Overcurrent protection circuit with automatic latching function |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111206280.8A CN113991600A (en) | 2021-10-16 | 2021-10-16 | Overcurrent protection circuit with automatic latching function |
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| CN113991600A true CN113991600A (en) | 2022-01-28 |
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| CN202111206280.8A Pending CN113991600A (en) | 2021-10-16 | 2021-10-16 | Overcurrent protection circuit with automatic latching function |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115865062A (en) * | 2023-02-20 | 2023-03-28 | 浙江国利信安科技有限公司 | Digital quantity output module |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111585247A (en) * | 2020-06-09 | 2020-08-25 | 深圳青铜剑技术有限公司 | Overcurrent protection circuit |
| CN111864697A (en) * | 2020-09-01 | 2020-10-30 | 臻驱科技（上海）有限公司 | Overcurrent protection circuit and method and system for judging whether power supply is overhauled |
| CN217307245U (en) * | 2021-10-16 | 2022-08-26 | 宁波普瑞均胜汽车电子有限公司 | Overcurrent protection circuit with latch function |
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2021
- 2021-10-16 CN CN202111206280.8A patent/CN113991600A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111585247A (en) * | 2020-06-09 | 2020-08-25 | 深圳青铜剑技术有限公司 | Overcurrent protection circuit |
| CN111864697A (en) * | 2020-09-01 | 2020-10-30 | 臻驱科技（上海）有限公司 | Overcurrent protection circuit and method and system for judging whether power supply is overhauled |
| CN217307245U (en) * | 2021-10-16 | 2022-08-26 | 宁波普瑞均胜汽车电子有限公司 | Overcurrent protection circuit with latch function |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115865062A (en) * | 2023-02-20 | 2023-03-28 | 浙江国利信安科技有限公司 | Digital quantity output module |
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