CN205489498U - Overcurrent protection circuit - Google Patents
Overcurrent protection circuit Download PDFInfo
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- CN205489498U CN205489498U CN201521101464.8U CN201521101464U CN205489498U CN 205489498 U CN205489498 U CN 205489498U CN 201521101464 U CN201521101464 U CN 201521101464U CN 205489498 U CN205489498 U CN 205489498U
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Abstract
The utility model discloses an overcurrent protection circuit, wherein, include: the one end junction current input of second resistance and first resistance, the negative input end of first amplifier is connected to the other end of first resistance, first diode is connected between the output and negative input end of first amplifier, and its positive pole is connected with the output of first amplifier, the one end of fourth resistance and the negative terminal of second amplifier are connected to the other end of second resistance, and the other end of fourth resistance is connected to the positive pole of second diode, and third resistance is parallelly connected with first diode and second diode. The equal ground connection of anode of first amplifier and second amplifier, the 5th ohmic connection between the negative input end and output of second amplifier, first electric capacity and the 5th resistor parallel with, the output of the 6th ohmic connection second amplifier, the other end ground connection of second electric capacity, second electric capacity is connected to the other end of the 6th resistance.
Description
Technical field
This utility model includes active power filter technical field, particularly to a kind of current foldback circuit.
Background technology
Along with the complexity of current electric grid load is various, harmonic wave and the quality of power supply such as idle the problem caused is the most serious.Electrical network and electrical equipment have relevant criterion to limit harmonic content,
Fig. 1 show the fundamental diagram of Active Power Filter-APF, with reference to Fig. 1, Active Power Filter-APF (being called for short APF) is a kind of dynamic suppression harmonic wave and the power electronic equipment of compensating reactive power, be equivalent to a controllable current source, it is parallel to electrical network, by detecting the harmonic components of load current, produce in opposite direction electric current equal in magnitude with load harmonic current and inject electrical network, thus realize the compensation to system harmonics.The load current iL of Active Power Filter-APF is decomposed into first-harmonic component i f and harmonic components ih, active electric power filter to output current is i, the current waveform iL of load-side is gathered and current waveform i that Active Power Filter-APF self sends by analogue signal sample circuit 10, reference current i* is calculated by instruction current computing circuit 11, current follow-up control circuit 12 calculates main circuit control signal by closed loop control algorithm and realizes the electric current i accurate real-time tracking reference current i* of Active Power Filter-APF, 13 control signals of drive circuit amplify the IGBT power model being transferred to main circuit 14, complete the output of electric current i.Make reference current i*=ih, i.e. Active Power Filter-APF export identical harmonic cancellation load harmonic, then system side electric current is comprises only the fundamental current if of load-side, thus realizes the harmonic filtration effect to system.
If the Frequency point of test has resonance to occur in systems, over-current phenomenon avoidance is inevitable, for ensureing equipment safety, it is necessary to increase current foldback circuit within hardware.
Utility model content
The purpose of this utility model is to provide a kind of current foldback circuit, is used for solving problem of the prior art.
This utility model one current foldback circuit; wherein, including the first resistance, the second resistance, the 3rd resistance, the 4th resistance, the 5th resistance, the 6th resistance, the first amplifier, the second amplifier, the first electric capacity, the second electric capacity, the first diode and the second diode；One end of second resistance and the first resistance connects electric current input, and the other end of the first resistance connects the negative input end of the first amplifier；First diode is connected between outfan and the negative input end of the first amplifier, and the outfan of its anode and the first amplifier connects；The other end of the second resistance connects one end and the negative terminal of the second amplifier of the 4th resistance, and the anode of the second diode connects the other end of the 4th resistance, the 3rd resistance and the first diode and the second diodes in parallel.The equal ground connection of anode of the first amplifier and the second amplifier；5th resistance is connected between negative input end and the outfan of the second amplifier, the first electric capacity and the 5th resistor coupled in parallel；6th resistance connects the outfan of the second amplifier, and the other end of the 6th resistance connects the second electric capacity, the other end ground connection of the second electric capacity.
One embodiment of the current foldback circuit according to utility model, wherein, also includes: comparator, and the positive input terminal of this comparator connects reference current end, and the negative input end of comparator connects the 6th resistance, and the outfan of comparator is as the output of current foldback circuit.
Visible, originally it is the current foldback circuit of utility model, it is possible to effectively protection Active Power Filter-APF circuit.
Accompanying drawing explanation
Fig. 1 show the fundamental diagram of Active Power Filter-APF；
Fig. 2 show the circuit diagram of current foldback circuit.
Detailed description of the invention
For making the purpose of utility model, content and advantage clearer, below in conjunction with the accompanying drawings and embodiment, the detailed description of the invention of utility model is described in further detail.
Control system requires the radio-frequency component outside current sample controller to be filtered bandwidth, if it is that 2500Hz, i.e. second-order low-pass filter need to filter more than 2500Hz composition to ensure stablizing of controller that active filter compensates frequency.But containing high frequency ripple in actual current, even if instantaneous overcurrent also can damage main switching device, so overcurrent protection needs complete current waveform.Simultaneously because output current value is of ac, having just has negative, needs positive half cycle and negative half period all carry out ductility limit systems.
Fig. 2 show the circuit diagram of current foldback circuit; as in figure 2 it is shown, current foldback circuit includes: resistance R8, resistance R9, resistance R10, resistance R13, resistance R14, resistance R15, amplifier U2A, amplifier U2B, comparator U3A; electric capacity C5, electric capacity C6, diode D1 and diode D2.
With reference to Fig. 2, one end of resistance R9 and resistance R8 connects the negative input end of the other end connection amplifier U2A of electric current input IA1, resistance R8.Diode D1 connects between outfan and the negative input end of amplifier U2A, and its anode is connected with the outfan of amplifier U2A.The other end of resistance R9 connects one end and the negative terminal of amplifier U2B of resistance R13, and the anode of diode D2 connects the other end of resistance R13, and resistance R10 and diode D1 and diode D2 is in parallel.The equal ground connection of anode of amplifier U2A and amplifier U2B.Resistance R14 is connected between negative input end and the outfan of amplifier U2B, and electric capacity C5 is in parallel with resistance R14.Resistance R15 connects the outfan of amplifier U2B, and the other end of resistance R15 connects electric capacity C6 and the negative input end of comparator U3A, the other end ground connection of electric capacity C6.The anode of comparator U3A connects reference current end I_REF, and the outfan of comparator U3A is as the output of current foldback circuit.
With reference to Fig. 2, in current foldback circuit, first order amplifying circuit rectification circuit takes absolute value negative half-cycle current, and second level amplifying circuit filters the interference component in detection, and the third level is comparison circuit, exports alarm level I_PRO.The comment I_PRO that reports to the police is high level time normal, if APF output electric current exceedes alarm current, I_PRO drags down, by hardware circuit block output, and trigger controller, performed stream alert process in software.I_REF is the datum of alarm current, regulated power supply obtain through electric resistance partial pressure, calibrates alarm current threshold value by adjusting divider resistance.
Visible, originally it is the current foldback circuit of utility model, it is possible to effectively protection Active Power Filter-APF circuit.
The above is only the preferred implementation of utility model; it should be pointed out that, for those skilled in the art, on the premise of without departing from utility model know-why; can also make some improvement and deformation, these improve and deform the protection domain that also should be regarded as utility model.
Claims (2)
1. a current foldback circuit; it is characterized in that, including: the first resistance, the second resistance, the 3rd resistance, the 4th resistance, the 5th resistance, the 6th resistance, the first amplifier, the second amplifier, the first electric capacity, the second electric capacity, the first diode and the second diode；
One end of second resistance and the first resistance connects electric current input, and the other end of the first resistance connects the negative input end of the first amplifier；First diode is connected between outfan and the negative input end of the first amplifier, and the outfan of its anode and the first amplifier connects；The other end of the second resistance connects one end and the negative terminal of the second amplifier of the 4th resistance, and the anode of the second diode connects the other end of the 4th resistance, the 3rd resistance and the first diode and the second diodes in parallel；The equal ground connection of anode of the first amplifier and the second amplifier；5th resistance is connected between negative input end and the outfan of the second amplifier, the first electric capacity and the 5th resistor coupled in parallel；6th resistance connects the outfan of the second amplifier, and the other end of the 6th resistance connects the second electric capacity, the other end ground connection of the second electric capacity.
2. current foldback circuit as claimed in claim 1, it is characterised in that also including: comparator, the positive input terminal of this comparator connects reference current end, and the negative input end of comparator connects the 6th resistance, and the outfan of comparator is as the output of current foldback circuit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201521101464.8U CN205489498U (en) | 2015-12-25 | 2015-12-25 | Overcurrent protection circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201521101464.8U CN205489498U (en) | 2015-12-25 | 2015-12-25 | Overcurrent protection circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN205489498U true CN205489498U (en) | 2016-08-17 |
Family
ID=56660319
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201521101464.8U Expired - Fee Related CN205489498U (en) | 2015-12-25 | 2015-12-25 | Overcurrent protection circuit |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN205489498U (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106532626A (en) * | 2016-12-09 | 2017-03-22 | 大禹电气科技股份有限公司 | Instantaneous overcurrent protection circuit of medium-high voltage variable-frequency speed regulating device and frequency converter |
| CN107528295A (en) * | 2017-09-29 | 2017-12-29 | 中国西电电气股份有限公司 | A kind of three-phase protective circuit and method for VSC |
-
2015
- 2015-12-25 CN CN201521101464.8U patent/CN205489498U/en not_active Expired - Fee Related
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106532626A (en) * | 2016-12-09 | 2017-03-22 | 大禹电气科技股份有限公司 | Instantaneous overcurrent protection circuit of medium-high voltage variable-frequency speed regulating device and frequency converter |
| CN107528295A (en) * | 2017-09-29 | 2017-12-29 | 中国西电电气股份有限公司 | A kind of three-phase protective circuit and method for VSC |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20160817 Termination date: 20161225 |