CN107196269A - A kind of DC protection circuit and its guard method - Google Patents
A kind of DC protection circuit and its guard method Download PDFInfo
- Publication number
- CN107196269A CN107196269A CN201710502592.0A CN201710502592A CN107196269A CN 107196269 A CN107196269 A CN 107196269A CN 201710502592 A CN201710502592 A CN 201710502592A CN 107196269 A CN107196269 A CN 107196269A
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- Prior art keywords
- circuit
- diode
- resistance
- switching tube
- monitoring module
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Classifications
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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
- H02H3/087—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 for dc applications
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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
- H02H3/021—Details concerning the disconnection itself, e.g. at a particular instant, particularly at zero value of current, disconnection in a predetermined order
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03K—PULSE TECHNIQUE
- H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
- H03K17/28—Modifications for introducing a time delay before switching
- H03K17/284—Modifications for introducing a time delay before switching in field effect transistor switches
Abstract
The present invention relates to a kind of DC protection circuit and its guard method; including circuit supervision system and on-off circuit; the circuit supervision system includes monitoring module, delay circuit and the power circuit of working power is provided to monitoring module; the on-off circuit includes load and with load is connected to be supported on the switching tube being not damaged by under short circuit or overload for protecting; the drain electrode of the switching tube is connected with the input of monitoring module; the input of the delay circuit is connected with the output end of monitoring module, and its output end is connected with the grid of switching tube.Protection circuit of the present invention and its guard method; stability is high; cost is low, and cost performance is high, with very strong popularization and actual application value; for short circuit and overload using two kinds of counter-measures; short circuit and overload use different delay protection mechanism, pass through the slow shut-off of delay circuit controlling switch pipe, it is to avoid electronic equipment frequent switching is restarted; after failture evacuation, protection module need not be re-powered.
Description
Technical field
The present invention relates to a kind of protection circuit, and in particular to a kind of DC protection circuit and its guard method.
Background technology
If the electric current of power output end has been over the specification requirement of design, then this power supply is at overloading shape
State.The phenomenon of generation is that electric current is excessive, electrical equipment heating, and circuit overloads for a long time can reduce line insulation level, or even burn
Equipment or circuit；Reason is many, such as electrical equipment overload, line short, apparatus insulated destruction etc., such as motor hair
Raw stall, crane hangs motionless etc..
The factors such as component wear, meteorological condition influence or artificial destruction are all likely to result in the generation of short circuit phenomenon.By
In the resistance very little of wire, electric current during power supply short circuit on circuit can be very big.So big electric current, it is most likely that electricity can be caused
Source is damaged;More seriously, because electric current is too big, it can raise the temperature of wire, fire is likely to cause when serious.
Prior art can solve short circuit or overload problem, with circuit protection function.But do not account for
Some practical problems in being operated to circuit.It is not treat short circuit with overload with a certain discrimination first.When circuital current is more than specified
It is only to be overloaded to be not necessarily during electric current and there occurs that short circuit is also possible to.Such as mixer is during operation, once in a while
Run into the larger stirring object of volume and be blocked the motor generation stall that can not run well, mixer loop may be will result in
Electric current increases, and occurs overload phenomenon.But machine can overcome large volume stirring thing quickly to recover normal work.In above-mentioned feelings
Under condition, if machine can overcome overload to recover normal work in a short period of time, then just motor need not occur
Stall is considered as short circuit and directly disconnecting circuit, interrupts the operation of machine.Secondly, prior art does not also propose circuit malfunctions
Voltage comparator afterwards or the safeguard measure of Power Monitoring Unit, in addition, protection circuit after removal of faults on system, it is necessary to again
Upper electricity can just recover normal, and protection circuit needs electricity to restart.
To solve the above problems, being necessary to provide a kind of guard method and protection circuit for solving short circuit and overload.
The content of the invention
It is an object of the invention to provide a kind of DC protection circuit and its guard method, stability is high, for short circuit and
Overload passes through the slow shut-off that delay circuit controls circuit using two kinds of counter-measures, it is to avoid electronic equipment frequent switching weight
Open, after failture evacuation, load again access after can normal work, without re-powering.
To achieve the above object, present invention employs following technical scheme：
A kind of DC protection circuit, including circuit supervision system and on-off circuit, the circuit supervision system include monitoring module,
Delay circuit and the power circuit that working power is provided to monitoring module, the on-off circuit include load and are mutually used in conjunction with load
The switching tube being not damaged by under short circuit or overload, the drain electrode of the switching tube and the input of monitoring module are supported in protection
End is connected, and the input of the delay circuit is connected with the output end of monitoring module, and its output end is connected with the grid of switching tube.
Further, the circuit supervision system also includes fault display circuit, the input of the fault display circuit
It is connected with the output end of monitoring module.
Further, the switching tube includes metal-oxide-semiconductor Q1, Q2, Q3, Q4, and described metal-oxide-semiconductor Q1, Q2, Q3, Q4 grid are equal
Be connected with the output end of delay circuit, metal-oxide-semiconductor Q1, Q2, Q3, Q4 drain electrode are connected with monitoring module, metal-oxide-semiconductor Q1, Q2, Q3,
Q4 source ground is simultaneously connected through power supply DC with the input loaded, metal-oxide-semiconductor Q1, Q2, Q3, Q4 grid respectively through electric capacity C4,
C5, C6, C7 are grounded.
Further, the monitoring module includes dual operational amplifier U1 and diode D5, D6, D7, D8, and the computing is put
Big device U1 includes comparator one and comparator two, resistance R13, R18 and switching tube that the inverting input of comparator one is concatenated
Drain electrode be connected, resistance R14, R15 that the reverse input end of comparator two is concatenated are connected with the drain electrode of switching tube, two pole
Pipe D5 anode is connected with the inverting input of comparator two, and the moon through electric capacity C12 after in parallel with resistance R19 with diode D6
Pole is docked, and diode D5 negative electrode is connected with diode D6 anode, diode D6 minus earth, comparator one and comparator
Two output end is connected with delay circuit；The inverting input of the comparator one is connected with diode D7 anode, and through electricity
Hold C13 with being connected after resistance R20 parallel connections with diode D8 negative electrode, diode D7 negative electrode is docked with diode D8 anode,
Diode D8 minus earth.
Further, the delay circuit includes overload fault delay circuit and short trouble delay circuit, the overload
Failure extension circuit includes diode D3, and the anode of the diode D3 is grounded after being connected successively through resistance R6 with electric capacity C8, electricity
Grid connection of the node between R6 and electric capacity C8 through resistance R7 and switching tube is hindered, diode D3 negative electrode is through resistance R3 and switch
The grid connection of pipe；The short trouble delay circuit includes diode D4, and diode D4 anode is through resistance R4 and switching tube
Grid connection, its negative electrode through resistance R5 and switching tube grid connection.
Further, the power circuit include accurate adjustable voltage stabilizer U2, light emitting diode D0, voltage-regulator diode D1,
Diode D2, the plus earth of the accurate adjustable voltage stabilizer U2, its negative electrode resistance R10, R1 and diode D2 through two series connection
Negative electrode be connected, diode D2 anode is connected to obtain reference voltage, the anode of the accurate adjustable voltage stabilizer U2 with power supply
Ground connection, and resistance R8, R9, R12 through three series connection are connected with accurate adjustable voltage stabilizer U2 reference edge and negative electrode, resistance R8 and
The node between node and resistance R9 and resistance R12 between resistance R9 is connected with monitoring module respectively, for monitoring mould
Block provides different reference voltages；The anode of the light emitting diode D0 is connected through resistance R2 with power supply, the light emitting diode
D0 minus earth, and be connected with voltage-regulator diode D1 anode, voltage-regulator diode D1 negative electrode is connected with Power Monitoring Unit,
The two ends of the resistance R1 are parallel with resistance R11, and voltage-regulator diode D1 two ends are parallel with electric capacity C1, C2, C3.
Further, the fault display circuit includes diode D9, D10 and light emitting diode D11, the diode D9
It is connected with light emitting diode D11 negative electrode, and is connected with diode D10 anode, diode D9 anode is through resistance R21 and electricity
Source monitoring module connection, diode D9 negative electrode is connected with the output end of comparator one, diode D10 negative electrode comparator two
Output end is connected.
As shown from the above technical solution, DC protection circuit of the present invention and its guard method, stability are high, cost
Low, cost performance is high, with very strong popularization and actual application value, for short circuit and overload using two kinds of counter-measures, short circuit
Because electric current is excessive using the measure that rapidly switches off, overload gives certain response time and to failure using measure is turned off at a slow speed
Power Monitoring Unit has safeguard measure afterwards.Short circuit and overload use different delay protection mechanism, the excessive easy damage of short circuit current flow
Electronic equipment is ruined, passes through the shut-off that delay circuit controls metal-oxide-semiconductor, it is to avoid electronic equipment frequent switching is restarted.When short circuit or mistake
Carry after occurring, metal-oxide-semiconductor disconnects current supply circuit, after failture evacuation, load access again after can normal work, protection module need not
Re-power.
Brief description of the drawings
Fig. 1 is the circuit block diagram of the present invention；
Fig. 2 is the circuit diagram of switching tube of the present invention；
Fig. 3 is the circuit diagram of monitoring module of the present invention；
The circuit diagram of Fig. 4 delay circuits of the present invention；
Fig. 5 is the circuit diagram of power circuit of the present invention；
Fig. 6 is the circuit diagram of fault display circuit of the present invention.
Embodiment
The present invention will be further described below in conjunction with the accompanying drawings：
As shown in figure 1, the DC protection circuit of the present embodiment, including circuit supervision system and on-off circuit, circuit supervision system
Including monitoring module 1, fault display circuit 4, delay circuit 2 and the power circuit 3 to the offer working power of monitoring module 1, open
Powered-down road includes load 6, switching tube 5 and power supply DC, and the drain electrode of switching tube 5 is connected with the input of monitoring module 1, malfunction coefficient
The input of circuit 4 is connected with the output end of monitoring module 1, the input of delay circuit 2 and the output end phase of monitoring module 1
Even, the output end of delay circuit 2 is connected with the grid of switching tube 5, and the source electrode of switching tube 5 is connected with power supply DC negative pole, power supply
DC 7 positive pole is connected with load 6.
Delay circuit 2 includes overload fault delay circuit 21 and short trouble delay circuit 22, overload fault extension electricity
Road 21 includes diode D3, and diode D3 anode is grounded after being connected successively through resistance R6 with electric capacity C8, resistance R6 and electric capacity C8
Between grid connection of the node through resistance R7 and switching tube, the grid of diode D3 negative electrode through resistance R3 and switching tube connects
Connect；The short trouble delay circuit 22 includes diode D4, and diode D4 grid of the anode through resistance R4 and switching tube is connected,
Grid connection of its negative electrode through resistance R5 and switching tube.
The switching tube 5 of the present embodiment is used as the electronic switch of protection circuit, the on off operating mode of control protection electric circuit, to protect
Load 6 or power supply are under short circuit or overload from infringement.Monitoring module 1 is used for the terminal voltage of real-time detection switch pipe 5, right
Protection point electric current and protection point voltage are set respectively in overload and short-circuit two classes failure, with decision circuit whether in short circuit or mistake
Load state, and occur after short circuit or overload fault, monitoring module 1 is also provided with safeguard measure, prevents it from burning out.When terminal voltage is big
In short circuit or during overloading threshold voltage, the output high level start-up study of monitoring module 1 circuit 2, delay circuit 2 by short circuit information or
The controlled stage of switching tube 5 is given after overload messages delay, controlling switch pipe 5 disconnects on-off circuit, to protect power supply or load 6.
Load 6 is powered using dc source in the system, can be that high power load can also be small-power power consumption component.
The monitoring module 1 is used between the real-time input stage of detection switch pipe 5 and output stage electric current in terminal voltage, on-off circuit
Flow through load 6 successively by positive source, the input stage of switching tube 5 flows back to power cathode through the output stage of switching tube 5.Pass through switching tube 5
The through and off of controlling switch circuit, the on off operating mode of Simultaneous Switching pipe 5 is controlled by circuit supervision system.When detect short circuit or mistake
When carrying phenomenon, it is low level that the controlled stage of switching tube 5, which receives signal, and switching tube 5 is cut-off state, and on-off circuit disconnects.It is not short
When road or overload phenomenon, the controlled stage of switching tube 5 is high level, and switching tube 5 is conducting state, on-off circuit normal work.
As shown in Fig. 2 switching tube 5 is made up of metal-oxide-semiconductor Q1, metal-oxide-semiconductor Q2, metal-oxide-semiconductor Q3 and metal-oxide-semiconductor Q4, metal-oxide-semiconductor Q1, Q2,
Q3, Q4 grid are connected and are connected as the grid of switching tube 5 with the output end with delay circuit 2, metal-oxide-semiconductor Q1, Q2, Q3, Q4's
Drain electrode is connected and is connected as the drain electrode of switching tube 5 with monitoring module 1, and metal-oxide-semiconductor Q1, Q2, Q3, Q4 source electrode are used as switching tube 5
Source ground, the source electrode are connected through power supply DC 7 with the input of load 6, and metal-oxide-semiconductor Q1, Q2, Q3, Q4 grid are respectively through electric capacity
C4, C5, C6, C7 are grounded.
As shown in figure 3, the monitoring module 1 of the present embodiment includes model LM358 dual operational amplifier U1 and diode
D5, D6, D7, D8, dual operational amplifier U1 have two output ends, export two voltage comparative results, can detect circuit
In overload or short trouble, its output voltage or for high level " 1 " or low level " 0 ", the different malfunctions of correspondence.
The low and high level of LM358 output pins is used for the grid level for controlling metal-oxide-semiconductor and then controls being turned on or off for metal-oxide-semiconductor.Its internal bag
Two high-gains, independent, internal frequency compensation double operational are included, pin 3 and pin 2 are the in-phase input ends of comparator one
And reverse input end, pin 1 is the output end of comparator one；Pin 5 and pin 6 be comparator two in-phase input end and reversely
Input, pin 7 is the output end of comparator two.
Resistance R13, R18 that the inverting input of comparator one is concatenated are connected with the drain electrode of switching tube 5, comparator two
Resistance R14, R15 that reverse input end is concatenated are connected with the drain electrode of switching tube 5, are respectively used to whether detection circuit occurs short circuit
Or overload fault, diode D5 anode is connected with the inverting input of comparator two, and the moon through electric capacity C12 Yu diode D6
Pole is docked, and diode D5 negative electrode is connected with diode D6 anode, diode D6 minus earth, comparator two it is anti-phase defeated
Enter end with power supply DC 7 negative pole to be connected；The inverting input of comparator one is connected with diode D7 anode, and through electric capacity C13
It is connected after in parallel with resistance R20 with diode D8 negative electrode, diode D7 negative electrode is docked with diode D8 anode, diode
D8 minus earth.The grid level of metal-oxide-semiconductor is controlled stage, is controlled by dual operational amplifier U1 output levels.
Specifically, the tube voltage drop voltage of the metal-oxide-semiconductor sampled connects amplifier in circuit supervision module 1 by R18, R13
Reverse input pin 2, it is reversely defeated that the metal-oxide-semiconductor tube voltage drop voltage sampled connects amplifier in circuit supervision module 1 by R15, R14
Enter pin 6, be respectively used to whether detection circuit occurs short circuit or overload fault.Amplifier output signal connects delay circuit 2, delay
The output of circuit 2 is connected to metal-oxide-semiconductor control end grid level.The short trouble detection of amplifier output is signally attached to short trouble delay
Circuit 22, the overload fault detection of amplifier output is signally attached to overload fault delay circuit 21, the short circuit of amplifier output or mistake
Information carrying number controls metal-oxide-semiconductor grid step voltage by delay circuit 2, and then controls the on or off of metal-oxide-semiconductor, realizes overload or short circuit
When protection circuit effect.
As shown in figure 4, delay circuit 2 includes diode D3, D4, resistance R6, R7 that diode D3 anode is concatenated with
The grid of switching tube 5 is connected, and diode D3 resistance R3 of the negative electrode through series connection with it is connected with the grid of switching tube 5, resistance R6
Node between resistance R7 is grounded by electric capacity C8；Resistance R4 of the diode D4 anode through series connection with it and switching tube 5
Grid is connected, and diode D4 negative electrode is connected through resistance R5 with the grid of switching tube 5.The delay circuit 2 takes what classification was handled
Method, for overloading the delay protection mechanism different with short-circuit two classes failure.The excessive easy damage electronic equipment of short circuit current flow, it is real
Row metal-oxide-semiconductor rapidly switches off measure, and delay time is short；Overloading phenomenon, circuit system can be with self-healing, to avoid electricity sometimes
Sub- equipment frequent switching is restarted, so carrying out metal-oxide-semiconductor turns off at a slow speed measure, delay time is long.
As shown in figure 5, power circuit 3 includes accurate adjustable voltage stabilizer U2, light emitting diode D0, voltage-regulator diode D1, two
Pole pipe D2, accurate adjustable voltage stabilizer U2 plus earth, its negative electrode resistance R10, R1 and diode D2 through two series connection negative electrode
It is connected, diode D2 anode is connected to obtain reference voltage with power supply, accurate adjustable voltage stabilizer U2 plus earth, and through three
Resistance R8, R9, R12 of individual series connection are connected with accurate adjustable voltage stabilizer U2 reference edge and negative electrode, between resistance R8 and resistance R9
Node and resistance R9 and resistance R12 between node be connected respectively with monitoring module 1, for being provided not to monitoring module 1
Same reference voltage；Light emitting diode D0 anode is connected through resistance R2 with power supply, light emitting diode D0 minus earth, and with
Voltage-regulator diode D1 anode connection, voltage-regulator diode D1 negative electrode is connected with Power Monitoring Unit 1, and resistance R1 two ends are in parallel
There is resistance R11, voltage-regulator diode D1 two ends are parallel with electric capacity C1, C2, C3.Power circuit 3 is that monitoring module 1 provides work electricity
Source, while providing suitable reference voltage for monitoring module 1.
As shown in fig. 6, fault display circuit 4 includes diode D9, D10 and light emitting diode D11, diode D9 is with lighting
Diode D11 negative electrode is connected, and is connected with diode D10 anode, and diode D9 anode is through resistance R21 and Power Supply Monitoring
Module 1 is connected.The fault display circuit 4 is used to show fault message.Fault display circuit 4 has a light emitting diode, is used for
Display short circuit or overload fault, when faulty generation, light emitting diode is lit.
Circuit operation principle is as follows：Metal-oxide-semiconductor is as protection switch pipe 5, the controlled stage grid of metal-oxide-semiconductor when loop does not have failure
Level is high level " 1 ", and switching tube 5 is turned on, loop normal work；When overload fault or short trouble occur for loop, in delay
Under conditions of system fails to recover automatically normal condition in buffer time, the grid level of metal-oxide-semiconductor is low level " 0 ", 5 sections of switching tube
Only, circuit loop is disconnected until failture evacuation.Metal-oxide-semiconductor serves the effect of switch in whole loop.
The setting of two in-phase voltage comparator reference voltage is protected by the short-circuit voltage of circuit in dual operational amplifier U1
Point and overload voltage protection point are determined.It is first depending on circuit rated current setting short circuit current flow protection point and overload current protection
Point, then calculates according to Ohm's law and metal-oxide-semiconductor internal resistance and obtains short-circuit voltage protection point and overload voltage protection point.Double computings are put
The big device U1 input voltage of pin 3 is short-circuit protection point reference voltage, and the input voltage of pin 5 is overload protection point reference voltage,
Short-circuit protection point reference voltage is higher than overload protection point reference voltage, therefore input electricity of the input voltage higher than pin 5 of pin 3
Pressure.
In view of metal-oxide-semiconductor and the working characteristics of amplifier, the amplifier input resistance accessed in circuit is very big, dual operational amplifier
The resistance that U1 reverse input end connects not attrition voltage substantially, metal-oxide-semiconductor drain sampled voltage is by the resistive transmission of concatenation to double
Operational amplifier U1 reverse input end, metal-oxide-semiconductor drain sampled voltage is substantially equal to dual operational amplifier U1 reverse input
Terminal voltage.When short circuit phenomenon occurs for circuit, the drain sampled voltage of metal-oxide-semiconductor is higher than short-circuit protection point reference voltage；Work as generation
When overloading phenomenon, the drain sampled voltage of metal-oxide-semiconductor is higher than overload protection point reference voltage but less than short-circuit protection point reference voltage；
If short circuit or open circuit fault do not occur for loop, drain sampled voltage is less than overload protection point reference voltage simultaneously also below short circuit
Protection point reference voltage.
When short circuit phenomenon occurs for circuit, dual operational amplifier U1 reverse input end voltage is higher than short-circuit protection point benchmark
Voltage, pin 2 and the input voltage of pin 6 are all higher than short-circuit protection point reference voltage, and the voltage of pin 2 is higher than the reference voltage of pin 3
And the voltage of pin 6 is higher than the reference voltage of pin 5, dual operational amplifier U1 two output pins 1 and pin 7 all export low electricity
Flat " 0 ", controls the grid level of metal-oxide-semiconductor to be low level " 0 ", ends metal-oxide-semiconductor by Fig. 2 short circuit and overload driving delay circuit 2,
Loop disconnects.
When overload phenomenon occurs for circuit, dual operational amplifier U1 reverse input end voltage is higher than overload protection point benchmark
Voltage but less than short-circuit protection point reference voltage, pin 2 and the input voltage of pin 6 are all higher than overload protection point reference voltage but low
In short-circuit protection point reference voltage, therefore the voltage of pin 6 is higher than the reference voltage of pin 5, and the pin 7 of voltage comparator exports low electricity
Flat " 0 ", the voltage of pin 2 is less than the reference voltage pin 1 of pin 3 output high level " 1 ".Due to short circuit and overload driving delay circuit
2 be that a diode concatenates one or two less resistance, can be ignored relative to 100K, works as voltage comparator
During LM358 any one output pin output low levels, rear class metal-oxide-semiconductor grid input low level " 0 ", metal-oxide-semiconductor is turned off, power supply
Stop output.
If short circuit or open circuit fault do not occur for loop, dual operational amplifier U1 pin 2 and the input voltage of pin 6 is all low
In short-circuit protection point reference voltage simultaneously less than overload protection point reference voltage, dual operational amplifier U1 two output pins
1 and pin 7 all export high level " 1 ", pass through short circuit and overload driving delay circuit 2 export high level " 1 " send into metal-oxide-semiconductor grid
Level, metal-oxide-semiconductor conducting, circuit normal work.
The electric current that loop current flows through metal-oxide-semiconductor when such as loading 6 circuit normal work is 72A, sets overload current to return
1.5 times of road rated current, overload current protection point is 108A, it is contemplated that the milliohm of metal-oxide-semiconductor internal resistance 3.7, four metal-oxide-semiconductors are simultaneously
The milliohm of internal resistance about 0.93 after connection, metal-oxide-semiconductor tube voltage drop is 108*0.93=0.1V, and overload protection point voltage is that 0.1V is that overload is protected
Shield point reference voltage is 0.1V；Overload current is set as 7.5 times of loop rated current, short circuit current flow protection point 540A, MOS
Pipe tube voltage drop is that 540*0.93=0.5V short-circuit voltages protection point is that 0.5V i.e. short-circuit protection point reference voltage is 0.5V.Double computings
Amplifier U1 two in-phase input ends are that the reference voltage of pin 3 and pin 5 is set to 0.5V and 0.1V, and the 0.5V of pin 3 is
Short-circuit protection point reference voltage, the 0.1V of pin 5 is overload protection point reference voltage.
When short circuit phenomenon occurs for load 6, metal-oxide-semiconductor drain sampled voltage is higher than 0.5V, causes the 2 of dual operational amplifier U1 to draw
Pin input voltage is higher than 3 pin reference voltages, the output low level of pin 1 " 0 ", while D grades of sampled voltages of metal-oxide-semiconductor are higher than 0.1V,
Dual operational amplifier U1 6 pin input voltages are caused to be higher than 5 pin reference voltages, pin 7 also exports low level " 0 ", rear class
Metal-oxide-semiconductor grid input low level, metal-oxide-semiconductor is turned off, and power supply stops output.Generation is overloaded without reaching during short dot, metal-oxide-semiconductor
Drain sampled voltage is less than 0.5V higher than 0.1V, now dual operational amplifier U1 1 pin output high level " 1 ", the output of 7 pins
Low-voltage " 0 ", the grid input low level of rear class metal-oxide-semiconductor, metal-oxide-semiconductor is turned off, and power supply stops output.Without short circuit or overload fault
During generation, back flow current is less than overload current and protects point 108A, again smaller than short circuit current protection point 540A, dual operational amplifier U1
6 pin input voltages and 3 pin input voltages less than overload protection point reference voltage also below short-circuit protection point reference voltage,
Pin 1 and pin 7 all export high level " 1 ", and the grid input high level " 1 " of rear class metal-oxide-semiconductor, metal-oxide-semiconductor conducting, circuit is normal
Work.
Embodiment described above is only that the preferred embodiment of the present invention is described, not to the model of the present invention
Enclose and be defined, on the premise of design spirit of the present invention is not departed from, technical side of the those of ordinary skill in the art to the present invention
In various modifications and improvement that case is made, the protection domain that claims of the present invention determination all should be fallen into.
Claims (8)
1. a kind of DC protection circuit, it is characterised in that：Including circuit supervision system and on-off circuit, the circuit supervision system
The power circuit of working power is provided including monitoring module, delay circuit and to monitoring module, the on-off circuit includes load
And be connected with load and be supported on the switching tube that is not damaged by under short circuit or overload for protecting, the drain electrode of the switching tube with
The input of monitoring module is connected, and the input of the delay circuit is connected with the output end of monitoring module, and its output end is with opening
The grid for closing pipe is connected.
2. DC protection circuit according to claim 1, it is characterised in that：The circuit supervision system is also aobvious including failure
Show circuit, the input of the fault display circuit is connected with the output end of monitoring module.
3. DC protection circuit according to claim 1, it is characterised in that：The switching tube include metal-oxide-semiconductor Q1, Q2, Q3,
Q4, described metal-oxide-semiconductor Q1, Q2, Q3, Q4 grid are connected with the output end of delay circuit, metal-oxide-semiconductor Q1, Q2, Q3, Q4 drain electrode
It is connected with monitoring module, metal-oxide-semiconductor Q1, Q2, Q3, Q4 source ground are simultaneously connected through power supply DC with the input loaded, MOS
Pipe Q1, Q2, Q3, Q4 grid are grounded through electric capacity C4, C5, C6, C7 respectively.
4. DC protection circuit according to claim 1, it is characterised in that：The monitoring module includes dual operational amplifier
U1 and diode D5, D6, D7, D8, the operational amplifier U1 include comparator one and comparator two, comparator one it is anti-phase defeated
Enter end resistance R13, R18 for being concatenated with the drain electrode of switching tube to be connected, the resistance that the reverse input end of comparator two is concatenated
R14, R15 are connected with the drain electrode of switching tube, and the anode of the diode D5 is connected with the inverting input of comparator two, and through electricity
Hold C12 with being docked after resistance R19 parallel connections with diode D6 negative electrode, diode D5 negative electrode is connected with diode D6 anode,
The output end of diode D6 minus earth, comparator one and comparator two is connected with delay circuit；The comparator one it is anti-
Phase input is connected with diode D7 anode, and is connected through electric capacity C13 after resistance R20 parallel connections with diode D8 negative electrode,
Diode D7 negative electrode is docked with diode D8 anode, diode D8 minus earth.
5. DC protection circuit according to claim 1, it is characterised in that：The delay circuit is delayed including overload fault
Circuit and short trouble delay circuit, the anode of the overload fault extension circuit including diode D3, the diode D3 according to
It is secondary connected through resistance R6 with electric capacity C8 after be grounded, the grid of node between resistance R6 and electric capacity C8 through resistance R7 and switching tube connects
Connect, diode D3 grid connection of the negative electrode through resistance R3 and switching tube；The short trouble delay circuit includes diode D4,
Grid connection of the diode D4 anode through resistance R4 and switching tube, grid connection of its negative electrode through resistance R5 and switching tube.
6. DC protection circuit according to claim 1, it is characterised in that：The power circuit includes accurate adjustable voltage stabilizing
Device U2, light emitting diode D0, voltage-regulator diode D1, diode D2, the plus earth of the accurate adjustable voltage stabilizer U2, its negative electrode
Resistance R10, R1 through two series connection are connected with diode D2 negative electrode, and diode D2 anode is connected to obtain benchmark electricity with power supply
Pressure, the plus earth of the accurate adjustable voltage stabilizer U2, and resistance R8, R9, R12 through three series connection and accurate adjustable voltage stabilizer
U2 reference edge and negative electrode connection, the node between node and resistance R9 and resistance R12 point between resistance R8 and resistance R9
It is not connected with monitoring module, for providing different reference voltages to monitoring module；The anode of the light emitting diode D0 is through electricity
Resistance R2 is connected with power supply, the minus earth of the light emitting diode D0, and is connected with voltage-regulator diode D1 anode, the pole of voltage stabilizing two
Pipe D1 negative electrode is connected with Power Monitoring Unit, and the two ends of the resistance R1 are parallel with resistance R11, voltage-regulator diode D1 two ends
It is parallel with electric capacity C1, C2, C3.
7. DC protection circuit according to claim 4, it is characterised in that：The fault display circuit includes diode
D9, D10 and light emitting diode D11, the diode D9 are connected with light emitting diode D11 negative electrode, and with diode D10 sun
Extremely it is connected, diode D9 anode is connected through resistance R21 with Power Monitoring Unit, diode D9 negative electrode is defeated with comparator one
Go out end to be connected, the output end of diode D10 negative electrode comparator two is connected.
8. the guard method of a kind of DC protection circuit according to claim 1, it is characterised in that comprise the following steps：
（1）Switching tube is connected with load, the break-make of control protection electric circuit；
（2）The terminal voltage of the real-time detection switch pipe of monitoring module, protection point electric current is set to overload and short-circuit two classes failure respectively
With protection point voltage, whether decision circuit is in short circuit or overload；
（3）When terminal voltage is more than short circuit or overload threshhold voltage, monitoring module output high level start-up study circuit, by prolonging
When circuit will give the controlled pole of switching tube after short circuit or overload messages delay, controlling switch pipe disconnects on-off circuit.
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| CN108574259A (en) * | 2018-06-22 | 2018-09-25 | 深圳市高胜科研电子有限公司 | A kind of protective device of direct current supply, system and control method |
| CN109526109A (en) * | 2018-12-24 | 2019-03-26 | 江阴华慧源电子技术有限公司 | A kind of solar street lamp controller load protection system |
| CN111682758A (en) * | 2020-06-15 | 2020-09-18 | 温州长江汽车电子有限公司 | Automobile light mixing system DCDC converter and detection method thereof |
| CN113364259A (en) * | 2021-06-11 | 2021-09-07 | 深圳市费思泰克科技有限公司 | Constant-current bleeder circuit with time-delay turn-off protection |
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Application publication date: 20170922 |