CN203707752U - Under-voltage protection circuit for frequency converter - Google Patents
Under-voltage protection circuit for frequency converter Download PDFInfo
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- CN203707752U CN203707752U CN201320757503.4U CN201320757503U CN203707752U CN 203707752 U CN203707752 U CN 203707752U CN 201320757503 U CN201320757503 U CN 201320757503U CN 203707752 U CN203707752 U CN 203707752U
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- optocoupler
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Abstract
The utility model discloses an under-voltage protection circuit for a frequency converter. Due to the fact that the voltage of the power grid is too low or a power phase is failure and the like, input voltage of the frequency converter is too low, so that the frequency converter possibly operates abnormally, when the condition is serious, the frequency converter is insufficient in torque and overlarge in current, and the frequency converter and a motor are possibly damaged. Aiming at the problems, the protection circuit used for reliably detecting whether the input voltage of the frequency converter is too low is provided. The under-voltage protection circuit comprises a three-phase power supply rectifier circuit, an optocoupler transmission circuit and a converting circuit. The under-voltage protection circuit can effectively make the frequency converter to stop operating immediately when a three-phase input power supply is undervoltage, and motor operation abnormity caused by the fact that the input voltage of the frequency converter is undervoltage is well solved. The under-voltage protection circuit is advantaged by high stability for a long time service, simple circuit structure, simple circuit maintenance and low cost and the like, and the influence of temperature and humidity on the circuit is little.
Description
Technical field
The utility model belongs to application of electronic technology field, specifically belongs to electric and electronic technical field, is specifically related to a kind of frequency converter under-voltage protecting circuit.
Background technology
Frequency converter is application converter technique, and the mode that is input to the frequency of the working power of alternating current motor by change is controlled the electric control appliance of motor, and then reaches energy-conservation and object speed governing.Along with improving constantly of industrial automatization, frequency converter is widely used.Because line voltage is too low or the reason such as power supply lacuna causes frequency converter input voltage too low, may cause frequency converter operation irregularity, when serious, can cause frequency converter torque deficiency, electric current is excessive, to such an extent as to damages the possibility of frequency converter and motor.Therefore, the under-voltage protecting circuit in frequency converter just seems particularly important.
Summary of the invention
The utility model, for the deficiencies in the prior art, has proposed a kind of frequency converter under-voltage protecting circuit.
A kind of frequency converter under-voltage protecting circuit of the utility model comprises three phase mains rectification circuit, optocoupler transmission circuit and change-over circuit.
Described three phase mains rectification circuit adopts 6 three-phase bridge rectification circuit and the first capacitor C 1 that rectifier diode M7 builds.Be input as the three-phase commercial power of 380V, be output as the direct current of 537V.
Described optocoupler transmission circuit comprises the first resistance R 1, the second resistance R 2, the 3rd resistance R 3, the 4th resistance R 4, the 5th resistance R 5, the 6th resistance R 6, the 7th resistance R 7, the 8th resistance R 8, optocoupler PC817 chip U1 and the second capacitor C 2.
First resistance R 1 one end is connected with the phase U in three-phase input current, and the other end is connected with one end of the second resistance R 2, an input mutually of the other end access rectifier bridge of the second resistance R 2; The 3rd resistance R 3 one end are connected with the phase V in three-phase input current, and the other end is connected with the 4th resistance R 4 one end, and another of the other end access rectifier bridge of the 4th resistance R 4 inputted mutually; The 5th resistance R 5 one end are connected with the phase W in three-phase input current, and the other end is connected with the 6th resistance R 6 one end, an input mutually again of the other end access rectifier bridge of the 6th resistance R 6; The positive pole of one termination bridge rectifier output of the 7th resistance R 7 connects, and the other end is connected with the positive pole of the light-emitting diode of optocoupler U1, and the negative pole of the light-emitting diode of optocoupler U1 is connected with bridge rectifier output ground negative pole; The E end of optocoupler U1 triode is connected with one end of the second capacitor C 2 and ground connection, and one end of the 8th resistance R 8 is connected with the C end of optocoupler U1 triode one side, another termination+5V power supply.The C end of optocoupler U1, as the output of optocoupler transmission circuit, is connected with change-over circuit.
Described change-over circuit comprises a Schmidt trigger D7, inverter D8 and single-chip microcomputer STM32F103VET6 chip U2.The input of Schmidt trigger D7 is connected with the output of optocoupler transmission circuit, and output end signal is sent into single-chip microcomputer STM32F103VET6 chip U2 and carried out AD sampling processing after reverser D8 is reverse.
The beneficial effects of the utility model: the utility model circuit can effectively make immediately frequency converter quit work in the time that three-phase input power is under-voltage, have solved the machine operation that frequency converter causes because input power is under-voltage abnormal better.In conjunction with single-chip microcomputer, STM32F103VET6 works together, and this circuit also has stable performance, the easy advantage of programming.
Accompanying drawing explanation
Fig. 1 is three-phase input power under-voltage protecting circuit.
Embodiment
As shown in Figure 1,
A kind of frequency converter under-voltage protecting circuit of the utility model comprises three phase mains rectification circuit, optocoupler transmission circuit and change-over circuit.
Described three phase mains rectification circuit adopts 6 three-phase bridge rectification circuit and the first capacitor C 1 that rectifier diode M7 builds.Be input as the three-phase commercial power of 380V, be output as the direct current of 537V.
Described optocoupler transmission circuit comprises the first resistance R 1, the second resistance R 2, the 3rd resistance R 3, the 4th resistance R 4, the 5th resistance R 5, the 6th resistance R 6, the 7th resistance R 7, the 8th resistance R 8, optocoupler PC817 chip U1 and the second capacitor C 2.
First resistance R 1 one end is connected with the phase U in three-phase input current, and the other end is connected with one end of the second resistance R 2, an input mutually of the other end access rectifier bridge of the second resistance R 2; The 3rd resistance R 3 one end are connected with the phase V in three-phase input current, and the other end is connected with the 4th resistance R 4 one end, and another of the other end access rectifier bridge of the 4th resistance R 4 inputted mutually; The 5th resistance R 5 one end are connected with the phase W in three-phase input current, and the other end is connected with the 6th resistance R 6 one end, an input mutually again of the other end access rectifier bridge of the 6th resistance R 6; The positive pole of one termination bridge rectifier output of the 7th resistance R 7 connects, and the other end is connected with the positive pole of the light-emitting diode of optocoupler U1, and the negative pole of the light-emitting diode of optocoupler U1 is connected with bridge rectifier output ground negative pole; The E end of optocoupler U1 triode is connected with one end of the second capacitor C 2 and ground connection, and one end of the 8th resistance R 8 is connected with the C end of optocoupler U1 triode one side, another termination+5V power supply.The C end of optocoupler U1, as the output of optocoupler transmission circuit, is connected with change-over circuit.
Described change-over circuit comprises a Schmidt trigger D7, inverter D8 and single-chip microcomputer STM32F103VET6 chip U2.The input of Schmidt trigger D7 is connected with the output of optocoupler transmission circuit, and output end signal is sent into single-chip microcomputer STM32F103VET6 chip U2 and carried out AD sampling processing after reverser D8 is reverse.
The principle whether this circuit judges three phase mains is under-voltage is: in the time that three-phase input power is greater than undervoltage warning threshold value, the current strength of optocoupler U1 input side can make the conducting of optocoupler U1 triode, the C end of triode is low level, then send into single-chip microcomputer U2 through Schmidt trigger D7 and inverter D8, what single-chip microcomputer U2 process AD sampling obtained is high level, can judge that three-phase input power is normal; When input power is during lower than undervoltage warning threshold value; the current strength of optocoupler U1 input side declines; make the cut-off of optocoupler U1 triode; triode C end is high level; send into single-chip microcomputer U2 through Schmidt trigger D7 and inverter D8, what single-chip microcomputer U2 process AD sampling obtained is that low level words just can judge that three-phase input power is too low, reports to the police; frequency converter is quit work, thereby can reach the object of protection frequency converter and motor.
In the time of normal work, what MCU accepted is high level always; When input voltage is during lower than 320V, the input current of optocoupler light-emitting diode one side is:
I
F=U/(R1+R2+R7)?≈6mA
Now the current transfer ratio CTR of optocoupler is 50%, and triode one side has electric current 3mA to flow through, and the voltage on R8 is reduced to: 3mA*0.5K=1.5V;
The voltage of optocoupler output is 5V-1.5V=3.5V; the voltage that is input to single-chip I/O mouth after Schmidt trigger and inverter is low level; single-chip microcomputer judges that now input voltage is too low thus, and stops immediately frequency converter work, and frequency converter and motor have been played to effective protective effect.
Claims (1)
1. a frequency converter under-voltage protecting circuit, comprises three phase mains rectification circuit, optocoupler transmission circuit and change-over circuit;
It is characterized in that: three phase mains rectification circuit adopts six three-phase bridge rectification circuit and the first capacitor C 1 that rectifier diode M7 builds;
Described optocoupler transmission circuit comprises the first resistance R 1, the second resistance R 2, the 3rd resistance R 3, the 4th resistance R 4, the 5th resistance R 5, the 6th resistance R 6, the 7th resistance R 7, the 8th resistance R 8, optocoupler PC817 chip U1 and the second capacitor C 2;
First resistance R 1 one end is connected with the phase U in three-phase input current, and the other end is connected with one end of the second resistance R 2, an input mutually of the other end access rectifier bridge of the second resistance R 2; The 3rd resistance R 3 one end are connected with the phase V in three-phase input current, and the other end is connected with the 4th resistance R 4 one end, and another of the other end access rectifier bridge of the 4th resistance R 4 inputted mutually; The 5th resistance R 5 one end are connected with the phase W in three-phase input current, and the other end is connected with the 6th resistance R 6 one end, an input mutually again of the other end access rectifier bridge of the 6th resistance R 6; The positive pole of one termination bridge rectifier output of the 7th resistance R 7 connects, and the other end is connected with the positive pole of the light-emitting diode of optocoupler U1, and the negative pole of the light-emitting diode of optocoupler U1 is connected with bridge rectifier output ground negative pole; The E end of optocoupler U1 triode is connected with one end of the second capacitor C 2 and ground connection, and one end of the 8th resistance R 8 is connected with the C end of optocoupler U1 triode one side, another termination+5V power supply; The C end of optocoupler U1, as the output of optocoupler transmission circuit, is connected with change-over circuit;
Described change-over circuit comprises a Schmidt trigger D7, inverter D8 and single-chip microcomputer STM32F103VET6 chip U2; The input of Schmidt trigger D7 is connected with the output of optocoupler transmission circuit, and output end signal is sent into single-chip microcomputer STM32F103VET6 chip U2 and carried out AD sampling processing after reverser D8 is reverse.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201320757503.4U CN203707752U (en) | 2013-11-27 | 2013-11-27 | Under-voltage protection circuit for frequency converter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201320757503.4U CN203707752U (en) | 2013-11-27 | 2013-11-27 | Under-voltage protection circuit for frequency converter |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN203707752U true CN203707752U (en) | 2014-07-09 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201320757503.4U Expired - Fee Related CN203707752U (en) | 2013-11-27 | 2013-11-27 | Under-voltage protection circuit for frequency converter |
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| Country | Link |
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| CN (1) | CN203707752U (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109980928A (en) * | 2019-04-24 | 2019-07-05 | 北京无线电测量研究所 | A kind of the channel power source Fault Isolation circuit and device of high input voltage T/R component |
-
2013
- 2013-11-27 CN CN201320757503.4U patent/CN203707752U/en not_active Expired - Fee Related
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109980928A (en) * | 2019-04-24 | 2019-07-05 | 北京无线电测量研究所 | A kind of the channel power source Fault Isolation circuit and device of high input voltage T/R component |
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| 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 |
Granted publication date: 20140709 Termination date: 20161127 |
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| CF01 | Termination of patent right due to non-payment of annual fee |