CN107342579B - AC/DC overcurrent protection and self-hold circuit - Google Patents
AC/DC overcurrent protection and self-hold circuit Download PDFInfo
- Publication number
- CN107342579B CN107342579B CN201710567202.8A CN201710567202A CN107342579B CN 107342579 B CN107342579 B CN 107342579B CN 201710567202 A CN201710567202 A CN 201710567202A CN 107342579 B CN107342579 B CN 107342579B
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- potentiometer
- relay
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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
-
- 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
-
- 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
- H02H3/06—Details with automatic reconnection
- H02H3/066—Reconnection being a consequence of eliminating the fault which caused disconnection
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- Emergency Protection Circuit Devices (AREA)
- Amplifiers (AREA)
- Protection Of Static Devices (AREA)
- Inverter Devices (AREA)
Abstract
AC/DC overcurrent protection of the invention and self-hold circuit; including amplifying circuit, inverter cricuit, over-current detection circuit, current sense resistor R8 and relay JD; one end of current sense resistor R8 is grounded, and the other end is connected to the non-inverting input terminal of U1A through normally closed point JDC, the resistance R7 of relay JD；Inverter cricuit is made of operational amplifier U1B, U1C and PNP type triode Q1；Over-current detection circuit is made of potentiometer Rw, NPN type triode Q2, and the base stage of Q2 is connected to the sliding end of potentiometer Rw, and the collector of Q2 is connected on control power supply through the coil JDL of relay.AC/DC overcurrent protection of the invention and self-hold circuit; both the amplification of AC or DC signal when input signal is normal can have been realized; input can be cut off when input current is excessive again; and keep dissengaged positions; and after super-high-current is inputted and is cut off; original state can be replied again, effectively realizes the protective effect to circuit element, and beneficial effect is significant.
Description
Technical field
The present invention relates to a kind of current foldback circuits, more specifically, more particularly to a kind of AC/DC overcurrent protection and from
Holding circuit.
Background technique
During to load supplying, over-current phenomenon avoidance may all occur due to power supply or the reason of load, at this
In the case of kind, if cannot be automatically cut off to overcurrent, the damage of power supply or load is easily caused even to cause fire etc.
Bigger disaster.If overcurrent protection circuit can be increased in circuit, when current is excessive, current path is automatically cut off, no
But it realizes to power supply and load protection effect and can be to avoid the appearance of bigger disaster, automatically cutting off should after current path
Keep this state until power supply completely cuts through power supply again.
Summary of the invention
The present invention in order to overcome the shortcomings of the above technical problems, provides a kind of AC/DC overcurrent protection and self-sustaining electricity
Road.
AC/DC overcurrent protection and self-hold circuit, including amplifying circuit, inverter cricuit, over-current detection of the invention is electric
Road, current sense resistor R8 and relay JD, amplifying circuit are made of operational amplifier U1A, resistance R1 and resistance R2, U1A
Inverting input terminal be grounded through resistance R1, resistance R2 is connected between the inverting input terminal of U1A and output end；It is characterized by: electric
One end ground connection of detection resistance R8 is flowed, the other end is connected to the non-inverting input terminal of U1A through normally closed point JDC, the resistance R7 of relay JD,
Both ends after R8 connects with normally closed point are parallel with resistance R9 for accessing current signal, the both ends after R8 connects with normally closed point, electricity
Hinder the resistance value 6-7 order of magnitude bigger than the resistance value of R8 of R7 and resistance R9；Both ends after diode D1 and diode D2 inverse parallel
It is connected between the non-inverting input terminal of U1A and ground；
The inverter cricuit is made of operational amplifier U1B, operational amplifier U1C and PNP type triode Q1；U1B's is same
Phase input terminal is connected with the output end of U1A, reverse inter-input-ing ending grounding, and output end is connected through resistance R6 with the base stage of Q1；U1C
Non-inverting input terminal be connected through resistance R5 with the output end of U1A, inverting input terminal is connected through resistance R3 with the output end of U1A
It connects, resistance R4 is in series between output end and its input terminal, resistance R3 is equal with the resistance value of R4；The emitter of triode Q1 connects
Ground, collector are connected with the inverting input terminal of U1C；
The over-current detection circuit is made of potentiometer Rw, NPN type triode Q2, and the both ends of potentiometer Rw are connected to respectively
The output end of U1C and ground, the base stage of Q2 are connected to the sliding end of potentiometer Rw, the emitter ground connection of Q2, the collector of Q2 pass through after
The coil JDL of electric appliance JD is connected on the anode of control power supply.
AC/DC overcurrent protection of the invention and self-hold circuit, the output end and potentiometer of the operational amplifier U1C
The diode D3 of buffer action is in series between Rw, the both ends of potentiometer Rw are parallel with the capacitor C played a filtering role；Relay
The both ends of the coil JDL of JD are parallel with diode D4 and warning circuit, and warning circuit is connected by light emitting diode and buzzer FMQ
It forms.
The resistance value of AC/DC overcurrent protection of the invention and self-hold circuit, the resistance R7 and resistance R9 are 100k
The resistance value of Ω, resistance R8 are 10m Ω；The resistance value of the resistance R1 and resistance R2 is respectively 10k Ω and 1M Ω.
AC/DC overcurrent protection of the invention and self-hold circuit, including by transformer, rectification circuit and voltage stabilizing chip
The power circuit of 78L05 and 79L05 composition, rectification circuit is the H bridge rectification circuit being made of diode D5, D6, D7 and D8, is become
The primary side of depressor is connected on 220V electric main, and secondary side is connected on H bridge rectification circuit；The output of rectification circuit is to pressure stabilizing core
Piece 78L05 and 79L05 power supply, the output of rectification circuit form control power supply；The output of 78L05 and 79L05 is respectively formed+5V
With the voltage output of -5V.
The beneficial effects of the present invention are: AC/DC overcurrent protection of the invention and self-hold circuit, by amplifying circuit, reverse phase
Circuit, over-current detection circuit, current sense resistor R8 and relay JD composition, inverter cricuit is by amplifier U1B, U1C and triode
Q1 composition, over-current detection circuit are made of triode Q2 and potentiometer Rw；The current signal of input is carried out through amplifying circuit first
Enhanced processing, when the signal of input is timing, Q1 cut-off, the output of inverter cricuit follows input signal, when the signal of input is
When negative, Q1 conducting, inverter cricuit carries out reverse phase to it, also exports the signal being positive；When the electric current of input is excessive, potentiometer Rw
The voltage of output end increases so that Q2 is connected, and the coil JDL of relay JD obtains electric, cutting input electric cur- rent measure resistance R8, realization
Circuit protection effect；Meanwhile input signal makes U1A continue to output larger signal through resistance R7 and diode D1 and D2, keeps
The conducting of Q2 continues the cutting for keeping resistance R8；After external excess current, which inputs, to cut off, U1A output is that 0, Q2 ends,
Overcurrent protection is restored.AC/DC overcurrent protection of the invention and self-hold circuit, can both realize when input signal is normal exchange or
The amplification of direct current signal, and input can be cut off when input current is excessive, and keep dissengaged positions, and when super-high-current inputs
After cutting, and original state can be replied, effectively realize the protective effect to circuit element, beneficial effect is significant.
Detailed description of the invention
Fig. 1 is the circuit diagram of AC/DC overcurrent protection of the invention and self-hold circuit.
Specific embodiment
The invention will be further described with embodiment with reference to the accompanying drawing.
As shown in Figure 1, the circuit diagram of AC/DC overcurrent protection of the invention and self-hold circuit is given, by amplification electricity
Road, inverter cricuit, over-current detection circuit, relay JD and current sense resistor R8 composition, amplifying circuit is by operational amplifier
U1A, resistance R1 and resistance R2 composition.Relay JD realizes overcurrent protection, one end ground connection of resistance R8, the other end and relay
The normally closed point JDC series connection of device JD is followed by the non-inverting input terminal in U1A.Both ends after R8 connects with normally closed point JDC are used to connect input
Current signal, the both ends after R8 connects with normally closed point JDC are also parallel with resistance R9.
The resistance value of resistance R7 and resistance R9 should be much larger than R8 resistance value (should be more than the 6-7 order of magnitude), as R7=R9=
100k Ω, R8=10m Ω, so that two ends after R7=R9=10000R8, diode D1 and diode D2 parallel connected in reverse phase are connected to U1A's
Between non-inverting input terminal and ground, in this way, the electric current for inputting the end A, B only passes through resistance R8, it is almost not passed through resistance R7 and R9；
Simultaneously as the resistance value very little of R8, so that Uin smaller (conducting voltage (0.5V or so) lower than diode D2), therefore just
In normal current detecting and amplification process, diode D2 is in off state, so that the voltage of U1A non-inverting input terminal is equal to Uin.
The inverting input terminal of U1A is grounded through resistance R1, is also in series with R2 between the inverting input terminal of U1A and its output end,
Material is thus formed the amplifying circuit that amplification factor is (R2+R1)/R1, i.e. Uo=[(R2+R1)/R1] * Uin.In R1=10k
In the case where Ω, R2=1M Ω, the amplification factor of amplifying circuit is 101 × 106。
Shown in inverter cricuit be made of operational amplifier U1B, operational amplifier U1C and positive-negative-positive diode Q1, U1B's
Reverse inter-input-ing ending grounding, non-inverting input terminal are connected with the output end of U1A, base stage phase of the output end through resistance R6 and triode Q1
Connection.The emitter of triode Q1 is grounded, and the collector of Q1 is connected with the non-inverting input terminal of U1C.The non-inverting input terminal of U1C passes through
Resistance R5 is connected with U1A output end, and the inverting input terminal of U1C is connected through resistance R3 with the output end of U1A, the reverse phase of U1C
Input terminal is connected with its output end through resistance R4, and resistance R3 is equal with the resistance value of resistance R4.
When input signal is timing, Vin > 0, Uo > 0, U1B export high level signal, Q1 cut-off, so that operation is put at this time
Output voltage Uout=Uo of big device U1C.When the signal of input is negative, Vin < 0, Uo < 0, U1B export low level letter at this time
Number, Q1 conducting, the non-inverting input terminal ground connection of U1C, so that output voltage Uout=- Uo of operational amplifier U1C.
Shown in over-current detection circuit be made of NPN type triode Q2 and potentiometer Rw, the both ends of potentiometer Rw connect respectively
In on ground and the output end of U1C, being in series with diode D3 between the output end and potentiometer Rw of U1C, diode D3 realizes isolation
Effect.The base stage of triode Q2 is connected with the sliding end of potentiometer Rw, the emitter ground connection of Q2, the collector and relay of Q2
The coil JDL series connection of JD is followed by the anode of control power supply.In this way, with the increase of input terminal A, B input current, U1C is defeated
Voltage Uout out is also gradually increased, and also will increase by the voltage that the sliding end of potentiometer Rw exports, when increasing to certain value
Meeting so that triode Q2 is connected, Q2 conducting meeting so that the coil JDL of relay obtain it is electric it is electric so that the normally closed point of relay disconnects
Circuit where hindering R8 is cut off, and input signal forms low current by resistance R9, while continuing to keep U1A defeated by R7, D1, D2
It givees a signal out, triode Q2 is held on, and continues the dissengaged positions in circuit where keeping R8.It is cut off when external excess current inputs
Afterwards, U1A output is that 0, Q2 ends, and overcurrent protection is restored.
The both ends of shown potentiometer Rw are parallel with capacitor C, for realizing filter action.The coil JDL's of shown relay
Both ends are parallel with diode D4 and warning circuit, and warning circuit is made of buzzer FMQ and light emitting diode, when the electric current of input
When more than setting value, Q2 conducting issues acousto-optic by buzzer FMQ and light emitting diode so that having electric current to pass through in warning circuit
Alarm signal.When Q2 becomes off state from being connected, diode D4 realizes that the afterflow to electric current in coil JDL acts on, and realizes
Protection to triode Q2.
Shown power circuit is made of transformer, rectification circuit and voltage stabilizing chip 78L05 and 79L05, and rectification circuit is served as reasons
The H bridge rectification circuit of diode D5, D6, D7 and D8 composition, the primary side of transformer is connected on 220V electric main, secondary to flank
In on H bridge rectification circuit；The output of rectification circuit powers to voltage stabilizing chip 78L05 and 79L05, and the output of rectification circuit forms control
Power supply processed；The output of 78L05 and 79L05 is respectively formed the voltage output of+5V He -5V.
Claims (4)
1. a kind of AC/DC overcurrent protection and self-hold circuit, including amplifying circuit, inverter cricuit, over-current detection circuit, electric current
Detection resistance R8 and relay JD, amplifying circuit are made of operational amplifier U1A, resistance R1 and resistance R2, and the reverse phase of U1A is defeated
Enter end to be grounded through resistance R1, resistance R2 is connected between the inverting input terminal of U1A and output end；It is characterized by: current detecting is electric
Hinder one end ground connection of R8, the other end is connected to the non-inverting input terminal of U1A through normally closed point JDC, the resistance R7 of relay JD, R8 with it is normally closed
For accessing current signal, the both ends after R8 connects with normally closed point JDC are parallel with resistance R9, resistance at both ends after point JDC series connection
The resistance value of R7 and resistance R9 the 6-7 order of magnitude bigger than the resistance value of R8；Two terminations after diode D1 and diode D2 inverse parallel
Between the non-inverting input terminal and ground of U1A；
The inverter cricuit is made of operational amplifier U1B, operational amplifier U1C and PNP type triode Q1；U1B's is same mutually defeated
Enter end to be connected with the output end of U1A, reverse inter-input-ing ending grounding, output end is connected through resistance R6 with the base stage of Q1；U1C's is same
Phase input terminal is connected through resistance R5 with the output end of U1A, and inverting input terminal is connected through resistance R3 with the output end of U1A, defeated
Resistance R4 is in series between outlet and its input terminal, resistance R3 is equal with the resistance value of R4；The emitter of triode Q1 is grounded, current collection
Pole is connected with the inverting input terminal of U1C；
The over-current detection circuit is made of potentiometer Rw, NPN type triode Q2, and the both ends of potentiometer Rw are connected to U1C's respectively
Output end and ground, the base stage of Q2 are connected to the sliding end of potentiometer Rw, and the emitter ground connection of Q2, the collector of Q2 is through relay JD
Coil JDL be connected to control power supply anode on.
2. AC/DC overcurrent protection according to claim 1 and self-hold circuit, it is characterised in that: the operational amplifier
The diode D3 of buffer action is in series between the output end and potentiometer Rw of U1C, the both ends of potentiometer Rw have been parallel with filter
The capacitor C of wave effect；The both ends of the coil JDL of relay JD are parallel with diode D4 and warning circuit, and warning circuit is by shining
Diode and buzzer FMQ are connected in series.
3. AC/DC overcurrent protection according to claim 1 or 2 and self-hold circuit, it is characterised in that: the resistance R7
Resistance value with resistance R9 is 100k Ω, and the resistance value of resistance R8 is 10m Ω；The resistance value of the resistance R1 and resistance R2 is respectively
10k Ω and 1M Ω.
4. AC/DC overcurrent protection according to claim 1 or 2 and self-hold circuit, it is characterised in that: including by transformation
The power circuit of device, rectification circuit and voltage stabilizing chip 78L05 and 79L05 composition, rectification circuit be by diode D5, D6, D7 and
The H bridge rectification circuit of D8 composition, the primary side of transformer are connected on 220V electric main, and secondary side is connected on H bridge rectification circuit；
The output of rectification circuit powers to voltage stabilizing chip 78L05 and 79L05, and the output of rectification circuit forms control power supply；78L05 and
The output of 79L05 is respectively formed the voltage output of+5V He -5V.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201710567202.8A CN107342579B (en) | 2017-07-12 | 2017-07-12 | AC/DC overcurrent protection and self-hold circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201710567202.8A CN107342579B (en) | 2017-07-12 | 2017-07-12 | AC/DC overcurrent protection and self-hold circuit |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN107342579A CN107342579A (en) | 2017-11-10 |
| CN107342579B true CN107342579B (en) | 2019-01-08 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201710567202.8A Active CN107342579B (en) | 2017-07-12 | 2017-07-12 | AC/DC overcurrent protection and self-hold circuit |
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| Country | Link |
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| CN (1) | CN107342579B (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109725190B (en) * | 2019-03-25 | 2020-11-03 | 贵州航天天马机电科技有限公司 | Alternating current-direct current signal multiple sampling protection system |
| CN110445498B (en) * | 2019-07-31 | 2021-10-08 | 西安天和防务技术股份有限公司 | Potential holding circuit and overcurrent protection circuit |
| CN114123115B (en) * | 2021-10-22 | 2023-08-08 | 苏州浪潮智能科技有限公司 | Electronic fuse protection device, board card and server |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN2300209Y (en) * | 1997-05-29 | 1998-12-09 | 张君冀 | Load monitoring electric machine protector |
| CN2728072Y (en) * | 2004-07-06 | 2005-09-21 | 边国泰 | Exponent type motor protector |
| CN202488089U (en) * | 2012-03-29 | 2012-10-10 | 介国安 | Self-staring overload protection circuit |
-
2017
- 2017-07-12 CN CN201710567202.8A patent/CN107342579B/en active Active
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN2300209Y (en) * | 1997-05-29 | 1998-12-09 | 张君冀 | Load monitoring electric machine protector |
| CN2728072Y (en) * | 2004-07-06 | 2005-09-21 | 边国泰 | Exponent type motor protector |
| CN202488089U (en) * | 2012-03-29 | 2012-10-10 | 介国安 | Self-staring overload protection circuit |
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| Publication number | Publication date |
|---|---|
| CN107342579A (en) | 2017-11-10 |
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