CN202405760U - Over-current protection circuit of frequency converter - Google Patents
Over-current protection circuit of frequency converter Download PDFInfo
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- CN202405760U CN202405760U CN2012200097376U CN201220009737U CN202405760U CN 202405760 U CN202405760 U CN 202405760U CN 2012200097376 U CN2012200097376 U CN 2012200097376U CN 201220009737 U CN201220009737 U CN 201220009737U CN 202405760 U CN202405760 U CN 202405760U
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Abstract
The utility model relates to an over-current protection circuit of a frequency converter. The over-current protection circuit comprises a current voltage conversion circuit, a voltage following circuit, a voltage rising circuit, a voltage comparison circuit and a protection output circuit, wherein the current voltage conversion circuit is connected with the voltage following circuit; the voltage following circuit is connected with the voltage rising circuit; the voltage rising circuit is connected with an input end of the voltage comparison circuit; and an output end of the voltage comparison circuit is connected with the protection output circuit. The over-current protection circuit of the frequency converter is simple, practicable and high in reliability.
Description
Technical field
The utility model relates to a kind of circuit, relates in particular to a kind of frequency converter circuit overcurrent protection.
Background technology
Frequency converter is an equipment commonly used in a kind of electric machine speed regulation process; Be used to realize the stepless speed regulation of alternating current machine, be widely used that frequency converter has adopted a large amount of power devices on circuit in the every field of national economy; And the frequency conducting with higher is cut-off; Very easily cause the misoperation of power device, and then cause the damage of frequency converter, must protect.
Overcurrent protection is the important protective device that frequency converter is able to trouble free service, causes the reason of overcurrent to have a lot, and such as frequency converter output short circuit owing to Insulation Problems, motor quickens too fast in startup and device for power switching misleads or the like.In practical application, the current foldback circuit mode of at present known frequency converter has two kinds:
Software protection
When guard signal occurring, provide the signal of a pulse or level, send into the interruption input pin of processor, processor responds interruption, and then blocks the output of PWM.Thereby protection power device; If program is made mistakes, then can't respond protection, consequence is serious.In addition, software protection needs certain response time, and real-time is not high.
Hardware protection
Hardware protection commonly used passes through a comparison circuit, when guard signal occurring, and comparator works, drive signal is closed; When fault-signal was eliminated, drive signal was recovered, and this protected mode is timely, but when drive signal is closed; If fault still exists, when drive signal is recovered, detect fault-signal again; Continue protection, under repeatedly impacting, power device still can damage.
The utility model content
The utility model technical problem to be solved provides a kind of simple and practical, frequency converter current foldback circuit that reliability is high.
The technical scheme that the utility model adopted is:
A kind of frequency converter current foldback circuit; It comprises current-to-voltage converting circuit, voltage follower circuit, voltage lifting circuit, voltage comparator circuit and protection output circuit; Described current-to-voltage converting circuit links to each other with voltage follower circuit; Described voltage follower circuit links to each other with voltage lifting circuit, and described voltage lifting circuit links to each other with the input of voltage comparator circuit, and the output of described voltage comparator circuit links to each other with the protection output circuit.
Press such scheme, described voltage comparator circuit adopts dual comparator LM293.
Press such scheme, described voltage follower circuit adopts amplifier TL082.
Press such scheme, described protection output circuit adopts triode MMB4403LT1.
Wherein: described current-to-voltage converting circuit is converted into voltage signal with the inverter current signal that collects; The input impedance of described voltage follower circuit is high, output impedance is low, and voltage signal and late-class circuit that current-to-voltage converting circuit is transmitted separate, and avoids late-class circuit that front stage circuits is formed and disturbs; Described voltage lifting circuit carries out lifting with the voltage signal that voltage follower circuit transmits; Described voltage comparator circuit compares the lifting voltage that voltage lifting circuit transmits with the setting threshold values; Described protection output circuit receives the level signal of voltage comparator circuit output, and will protect the controller that outputs signal to of output circuit, sends the over current fault signal after controller is judged and gives host computer.
During overcurrent; After current signal flows through sampling resistor and converts voltage signal to; Get into voltage comparator circuit through voltage lifting circuit; Send into the protection output circuit with setting upper current limit value or lower limit after relatively, protection output circuit output low level signal is given controller, sends the over current fault signal after controller is judged and gives host computer.
The beneficial effect of the utility model is: 1, simple and practical, reliability is high.2, current-to-voltage converting circuit converts the output current of frequency converter into voltage signal, utilizes input impedance height, the low characteristics and the late-class circuit of output impedance of voltage follower circuit to separate then, avoids late-class circuit that front stage circuits is formed and disturbs.3, increased voltage lifting circuit; Make negative current become positive voltage through after the lifting through the negative voltage signal after the conversion; So that send into voltage comparator circuit; Positive current upper limit threshold values and negative current lower limit threshold values through with voltage comparator circuit compare, thereby frequency converter is worked in the scope that satisfies its bound operating current.In case the output current of frequency converter surpasses the operating current of setting, and will export an over current fault signal and protect frequency converter.
Description of drawings
Fig. 1 is the theory diagram of the utility model.
Fig. 2 is the current-to-voltage converting circuit of the utility model and the catenation principle figure of voltage follower circuit.
Fig. 3 is the circuit theory diagrams of the reference voltage source V1 of the utility model.
Fig. 4 is the circuit theory diagrams of voltage lifting circuit, voltage comparator circuit and the protection output circuit of the utility model.
Embodiment
Further specify the embodiment of the utility model below in conjunction with accompanying drawing.
Referring to Fig. 1; A kind of frequency converter current foldback circuit; It comprises current-to-voltage converting circuit, voltage follower circuit, voltage lifting circuit, voltage comparator circuit and protection output circuit, and described current-to-voltage converting circuit links to each other with voltage follower circuit, and described voltage follower circuit links to each other with voltage lifting circuit; Described voltage lifting circuit links to each other with the input of voltage comparator circuit, and the output of described voltage comparator circuit links to each other with the protection output circuit.
Referring to Fig. 2; The output current signal IU1 of frequency converter is connected back ground connection with parallel resistor R8, R9; The in-phase end of amplifier U2 links to each other with current signal IU1; The end of oppisite phase of amplifier U2 links to each other through the voltage signal IU of resistance R 10 with output, and the output of amplifier U2 links to each other through the voltage signal IU of resistance R 10 with output.
Referring to Fig. 3, reference power source V1 is obtained by the adjustable shunting a reference source of three ends TL431.+ 15V voltage source is connected with reference voltage source V1 through resistance R 12; The end of reference voltage source V1 is connected with the negative electrode of a reference source U3; The plus earth of a reference source U3; The negative electrode of a reference source U3 is connected with the reference utmost point of a reference source U3 through resistance R 13, and the reference utmost point of a reference source U3 is connected with the anode of a reference source U3 through resistance R 14.(setting upper current limit value REF1, setting lower current limit value REF2 all is by obtaining with schematic circuit with Fig. 3).
Referring to Fig. 4, voltage signal IU is connected with an end of resistance R 1, and the other end of resistance R 1 is connected with reference voltage source V1 (reference voltage source V1 adopts the adjustable shunting a reference source of three ends TL431 to provide) with resistance R 2 series connection backs; The other end of described resistance R 1 also with being connected in series of resistance R 3, resistance R 4 after; Insert the reverse input end 1 and positive input 2 of dual comparator U1; The positive input 1 of dual comparator U1 connects sets upper current limit value REF1 (setting upper current limit value REF1 adopts the adjustable shunting a reference source of three ends TL431 to provide); The reverse input end 2 of dual comparator U2 connects sets lower current limit value REF2 (setting lower current limit value REF2 adopts the adjustable shunting a reference source of three ends TL431 to provide); The output of dual comparator U1 is connected with an end of resistance R 5; The other end of resistance R 5 is connected back access+5V power supply with resistance R 6, the other end of described resistance R 5 also is connected with the base stage of triode Q1, and the emitter of triode Q1 is connected with power supply+5V; The collector electrode of triode Q1 is connected with ground through R7, and the collector electrode of described triode Q1 is provided with the output OC that is connected with controller.
In the present embodiment; IU represents the voltage after the output current conversion; Resistance R 8, R9 form current-to-voltage converting circuit, and amplifier U2, resistance R 10, R11 form voltage follower circuit, and resistance R 1, resistance R 2 and reference voltage source V1 form voltage lifting circuit; Resistance R 3, resistance R 4, dual comparator U1 form voltage comparator circuit, and resistance R 5, resistance R 6, resistance R 7 and triode Q1 form the protection output circuit.It is LM293 that dual comparator U1 adopts model, and it is MMB4403LT1 that triode Q1 adopts model, and amplifier U2 adopts amplifier TL082.
The current signal of frequency converter is after current-to-voltage converting circuit changes into voltage signal; Behind voltage follower circuit, become voltage signal IU; The voltage lifting circuit that voltage signal IU forms through resistance R 1, resistance R 2 and reference voltage source V1; Resistance R 1 equates with resistance R 2 resistances in the voltage lifting circuit, voltage signal IU lifting 1/2nd reference voltage source V1.When voltage signal IU is negative value, after lifting, just become on the occasion of; When voltage signal IU be on the occasion of the time, only promoted certain value, its magnitude of voltage still is positive; So just convenient setting threshold values with voltage comparator circuit compares; Get into the voltage comparator circuit of forming by resistance R 3, resistance R 4 and dual comparator U1 through the voltage signal of voltage lifting circuit, send into the protection output circuit of forming by resistance R 5, resistance R 6, resistance R 7 and triode Q1 after relatively with setting upper current limit value REF1 or lower limit REF2; Setting upper current limit value REF1 on the dual comparator U1 in the voltage comparator circuit is the comparison reference point of positive current, and the setting lower current limit value REF2 on the dual comparator U1 in the voltage comparator circuit is the comparison reference point of negative current; When the output voltage of voltage lifting circuit has surpassed setting upper current limit value REF1 or set lower current limit value REF2, dual comparator U1 is with regard to the output low level signal; At this moment, triode Q1 conducting, the output OC output low level of the collector electrode of triode Q1.In like manner, setting between upper current limit value REF1 and the setting lower current limit value REF2 when the output voltage values of voltage lifting circuit, dual comparator U1 just exports high level signal, and triode Q1 ends, the output OC output high level of the collector electrode of triode Q1.So, only need the output OC level state of the collector electrode of judgement triode Q1 just can judge whether the frequency converter overcurrent.
The above; Only being the preferred embodiment of the utility model, is not that the utility model is done any pro forma restriction, and those skilled in the art utilize the technology contents of above-mentioned announcement to make a little simple modification; Equivalent variations or modification all drop in the protection range of the utility model.
Claims (4)
1. frequency converter current foldback circuit; It is characterized in that: it comprises current-to-voltage converting circuit, voltage follower circuit, voltage lifting circuit, voltage comparator circuit and protection output circuit; Described current-to-voltage converting circuit links to each other with voltage follower circuit; Described voltage follower circuit links to each other with voltage lifting circuit; Described voltage lifting circuit links to each other with the input of voltage comparator circuit after with the voltage signal lifting, and the output of described voltage comparator circuit links to each other with the protection output circuit.
2. frequency converter current foldback circuit as claimed in claim 1 is characterized in that: described voltage comparator circuit adopts dual comparator LM293.
3. frequency converter current foldback circuit as claimed in claim 1 is characterized in that: described protection output circuit adopts triode MMB4403LT1.
4. frequency converter current foldback circuit as claimed in claim 1 is characterized in that: described voltage follower circuit adopts amplifier TL082.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2012200097376U CN202405760U (en) | 2012-01-10 | 2012-01-10 | Over-current protection circuit of frequency converter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2012200097376U CN202405760U (en) | 2012-01-10 | 2012-01-10 | Over-current protection circuit of frequency converter |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN202405760U true CN202405760U (en) | 2012-08-29 |
Family
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN2012200097376U Expired - Lifetime CN202405760U (en) | 2012-01-10 | 2012-01-10 | Over-current protection circuit of frequency converter |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN202405760U (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104218532A (en) * | 2014-09-19 | 2014-12-17 | 中冶南方（武汉）自动化有限公司 | Voltage protection circuit for frequency converter direct current (DC) bus |
| CN106451363A (en) * | 2016-09-21 | 2017-02-22 | 珠海格力电器股份有限公司 | Protection circuit of bidirectional converter, and power system with electricity storage function |
| CN104167710B (en) * | 2014-08-07 | 2017-11-10 | 石狮市酷瑞电气有限责任公司 | A kind of short-circuit protection circuit of frequency changer direct current bus |
-
2012
- 2012-01-10 CN CN2012200097376U patent/CN202405760U/en not_active Expired - Lifetime
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104167710B (en) * | 2014-08-07 | 2017-11-10 | 石狮市酷瑞电气有限责任公司 | A kind of short-circuit protection circuit of frequency changer direct current bus |
| CN104218532A (en) * | 2014-09-19 | 2014-12-17 | 中冶南方（武汉）自动化有限公司 | Voltage protection circuit for frequency converter direct current (DC) bus |
| CN106451363A (en) * | 2016-09-21 | 2017-02-22 | 珠海格力电器股份有限公司 | Protection circuit of bidirectional converter, and power system with electricity storage function |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CX01 | Expiry of patent term |
Granted publication date: 20120829 |
|
| CX01 | Expiry of patent term |