CN203274949U - Over-temperature detection and protection circuit of current transformer - Google Patents
Over-temperature detection and protection circuit of current transformer Download PDFInfo
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- CN203274949U CN203274949U CN 201320307503 CN201320307503U CN203274949U CN 203274949 U CN203274949 U CN 203274949U CN 201320307503 CN201320307503 CN 201320307503 CN 201320307503 U CN201320307503 U CN 201320307503U CN 203274949 U CN203274949 U CN 203274949U
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Abstract
The utility model discloses an over-temperature detection and protection circuit of a current transformer and belongs to the field of power electronic current transformer technology. The over-temperature detection and protection circuit comprises a temperature acquisition filter circuit (1), a maximum value selection circuit (2), an optical coupler isolation circuit (3), a voltage reference source circuit (4) and an over-temperature hysteresis comparison circuit (5). The voltage reference source circuit (4) is separately connected with the temperature acquisition filter circuit (1) and the over-temperature hysteresis comparison circuit (5), and the temperature acquisition filter circuit (1), the maximum value selection circuit (2), the optical coupler isolation circuit (3) and the over-temperature hysteresis comparison circuit (5) are successively connected. The over-temperature detection and protection circuit of the current transformer is advantageous in that the over-temperature detection and protection circuit is completely based on hardware, without being controlled by a main control chip of the current transformer, and is characterized by fastness, safety, reliability and the like; and compared with software protection, the over-temperature detection and protection circuit is capable of reacting quickly and starting a protection mechanism automatically when an over-temperature fault occurs, and even the main control chip of the current transformer is invalid, the over-temperature detection and protection circuit is capable of starting the protection mechanism, so the current transformer and other external devices can be effectively protected.
Description
Technical field
The utility model belongs to the electronic power convertor technical field, particularly provides a kind of current transformer excess temperature to detect and holding circuit, and the excess temperature that is applicable to current transformator power module and heating radiator thereof detects and protection.
Technical background
Along with the development of Power Electronic Technique, the application of current transformer is increasingly extensive, as photovoltaic DC-to-AC converter, wind electric converter, frequency converter etc.High-power switch device IGBT etc. are higher as core component and the price of current transformer, in case its damage just can cause the collapse of whole system, thereby are the factors that current transformer defencive function when design needs emphasis to consider.In the current transformer course of work; due to its operating characteristic; high-power switch device need to bear larger electric current and voltge surge; in the situation that electrical network, load or current transformer itself break down; the electric current that tends to cause flowing through device surpasses rapidly its allowed band; due to the restriction that is subject to manufacturing process, power device in this case usually can be because excess temperature damages, so excess temperature detects and the design of holding circuit is a requisite ring in current transformer protection design.
The current transformer overheat protector has software protection and hardware protection two aspects usually; what deadlock arranged during long and work due to the conservation treatment cycle of the main control chip of current transformer may; and usually just can cause in a short period of time the damage of power device when the excess temperature fault occurs, so software protection is usually as the stand-by protection measure.Sudden and rapidity during based on the strongly disturbing characteristics of current transformer major loop high-voltage large current and excess temperature fault; therefore be necessary to design a kind of quick, safe and reliable hardware thermal-shutdown circuit; can reaction and starting protection mechanism rapidly automatically when the excess temperature fault occurs, have simultaneously simplicity of design, characteristics with low cost.
Summary of the invention
The purpose of this utility model is to provide a kind of current transformer excess temperature to detect and holding circuit, can react current transformer excess temperature fault fast, safely, reliably, and protection current transformer and external unit thereof are not damaged.
The utility model comprises: temperature acquisition filtering circuit 1, auctioneering circuit 2, optical coupling isolation circuit 3, voltage reference source circuit 4, the stagnant chain rate of excess temperature are than circuit 5.Wherein voltage reference source circuit 4 is connected than circuit 5 with the stagnant chain rate of temperature acquisition filtering circuit 1 and excess temperature respectively, for it provides reference voltage.Temperature acquisition filtering circuit 1, auctioneering circuit 2, optical coupling isolation circuit 3, the stagnant chain rate of excess temperature are connected successively than circuit 5, and the stagnant chain rate of excess temperature is than circuit 5 output excess temperature fault-signals.
Temperature acquisition filtering circuit 1 described in the utility model is comprised of 3 road identical collection filtering circuits, and wherein every road all is comprised of 5V voltage-reference, thermistor, sampling resistor and RC filtering circuit.The 5V voltage-reference provides voltage reference, and thermistor and sampling resistor carry out dividing potential drop, the change in voltage of getting on sampling resistor during temperature variation, the radio-frequency component of RC filtering circuit filtering sampled signal.Usually choose sampling resistor and equal the corresponding thermistor resistance of excess temperature threshold value, for the thermistor of negative temperature coefficient, during excess temperature, sampled signal voltage is lower than 2.5V.
Optical coupling isolation circuit 3 described in the utility model is comprised of 2 operational amplifiers, 1 opto-coupler chip and 1 5V insulating power supply module.Opto-coupler chip has carried out electrical isolation with rear class conservation treatment circuit and temperature collection circuit, current transformer major loop; 2 operation amplifier circuits are respectively as the input and output of opto-coupler chip; the normal operation of assurance opto-coupler chip; usually the resistance of selecting 2 photodiodes to be connected is identical, and the both sides magnitude of voltage of light-coupled isolation is identical like this.5V insulating power supply module provides the 5V power supply of isolation for optical coupling isolation circuit two ends.
Voltage reference source circuit 4 described in the utility model is comprised of 2 voltage stabilizing chips and 2 operational amplifiers.The 1st voltage stabilizing chip provides the 5V reference voltage for temperature acquisition filtering circuit 1, guarantees the accurate of temperature acquisition, and wherein the 2.5V voltage of voltage stabilizing chip output amplifies 2 times through operational amplifier, obtains the 5V reference voltage.The 2nd voltage stabilizing chip provides the 2.5V reference voltage for the stagnant chain rate of excess temperature than circuit 5, and this reference voltage is obtained after the operational amplifier voltage follow by the 2.5V voltage of voltage stabilizing chip output.Due to temperature acquisition filtering circuit 1 and the stagnant chain rate of excess temperature than circuit 5 electrical isolation, therefore voltage reference source circuit is by two groups of voltage stabilizing chip designs.
The stagnant chain rate of excess temperature described in the utility model is comprised of 1 comparer and 1 diode than circuit 5.Comparator design becomes adjustable limit value hysteresis comparator form, and the in-phase input end of comparer is connected to 2.5V voltage reference and potentiometer, the temperature voltage signal of anti-phase input termination front stage circuits output.Be connected to light emitting diode between the output terminal of comparer and 5V power supply, when the comparer output low level, diode is lighted, indication excess temperature malfunction.The thresholding width of hysteresis comparator can be avoided near the frequent protection action the excess temperature limit value.The resistance that changes potentiometer can change the excess temperature threshold value.The excess temperature fault-signal of excess temperature hysteresis comparator output is carried out hardware logic with current transformer driving signal and computing just can be blocked rapidly driving pulse, thereby stop current transformer, complete the protection process.
Temperature collection circuit utilizes thermistor to detect the current transformer Temperature Quantity; auctioneering circuit can be chosen maximum temperature from the multi way temperature that gathers; optical coupling isolation circuit is guaranteed effective electrical isolation between current transformer major loop and control circuit; stagnant chain rate is than circuit output fault-signal and improve the holding circuit antijamming capability; voltage reference source circuit provides voltage reference for temperature acquisition filtering circuit and stagnant chain rate than circuit; excess temperature fault-signal and current transformer are driven signal carry out the hardware logic computing and can block rapidly driving pulse, thereby stop current transformer.This circuit is fully based on hardware design; do not control by the current transformer main control chip; and have advantages such as quick, safe, reliable; than software protection; can when occuring, the excess temperature fault react rapidly and automatic starting protection mechanism; even also can move by starting protection in the situation that the current transformer main control chip loses efficacy, thereby can more effectively protect current transformer and external unit thereof.
Description of drawings
Fig. 1 is circuit structure of the present utility model.Wherein, temperature acquisition filtering circuit 1, auctioneering circuit 2, optical coupling isolation circuit 3, voltage reference source circuit 4, the stagnant chain rate of excess temperature are than circuit 5.
Fig. 2 is physical circuit of the present utility model.Wherein, temperature acquisition filtering circuit 1, auctioneering circuit 2, optical coupling isolation circuit 3, voltage reference source circuit 4, the stagnant chain rate of excess temperature are than circuit 5.
Embodiment
The utility model comprises: temperature acquisition filtering circuit 1, auctioneering circuit 2, optical coupling isolation circuit 3, voltage reference source circuit 4, the stagnant chain rate of excess temperature are than circuit 5.Wherein voltage reference source circuit 4 is connected than circuit 5 with the stagnant chain rate of temperature acquisition filtering circuit 1 and excess temperature respectively, for it provides reference voltage.Temperature acquisition filtering circuit 1, auctioneering circuit 2, optical coupling isolation circuit 3, the stagnant chain rate of excess temperature are connected successively than circuit 5, and the stagnant chain rate of excess temperature is than circuit 5 output excess temperature fault-signals.
In order more specifically to describe the utility model, below in conjunction with drawings and the specific embodiments, the technical solution of the utility model and relative theory thereof are elaborated.The below is only in order to provide the utility model clearly to be explained by example of the present utility model being shown to the description of embodiment.The utility model never is limited to any concrete configuration that proposes below, but has covered any modification, replacement and the improvement of coherent element or parts under the prerequisite that does not break away from the utility model spirit.
As shown in Figure 1, the utility model comprises: temperature acquisition filtering circuit 1, auctioneering circuit 2, optical coupling isolation circuit 3, voltage reference source circuit 4, the stagnant chain rate of excess temperature are than circuit 5.Wherein voltage reference source circuit 4 is connected than circuit 5 with the stagnant chain rate of temperature acquisition filtering circuit 1 and excess temperature respectively, for it provides reference voltage.Temperature acquisition filtering circuit 1, auctioneering circuit 2, optical coupling isolation circuit 3, the stagnant chain rate of excess temperature are connected successively than circuit 5, and the stagnant chain rate of excess temperature is than circuit 5 output excess temperature fault-signals.
As shown in Figure 2, described temperature acquisition filtering circuit 1 is made of 3 road temperature signals of sampling altogether 3 road identical collection filtering circuits.Describe take the 1 the road as example, this circuit is comprised of voltage-reference 5VREF, thermistor Rt1, sampling resistor R1 and RC filtering circuit R4, C1.5VREF provides voltage reference, carries out dividing potential drop by Rt1 and R1, the change in voltage of getting on R1 during temperature variation, the RC filtering circuit filtering radio-frequency component that the voltage signal on R1 forms through R4, C1.Usually choose sampling resistor and equal the corresponding thermistor resistance of excess temperature threshold value, for the thermistor of negative temperature coefficient, during excess temperature, sampled signal voltage is lower than 2.5V.
Described auctioneering circuit 2, formed with diode and operational amplifier U1A, the U1B, the U2A that are connected into the voltage follower circuit form by 3 output terminals, 3 output terminals are connected to public output and are connected to over the ground resistance R 10, C4, C5 are the decoupling capacitance of amplifier chip LM358D, R7, R8, R9 are the peripheral circuit of amplifier, diode D1, D2, D3 common cathode, its conducting depends on which anode voltage is high, and R10 can prevent above 3 operational amplifier output terminals open circuit and can't work.3 amplifiers all are connected into the voltage follower form, so this circuit can select the maximum temperature value to be input to post processing electric circuit from 3 road temperature acquisition signals.During practical application, overheat protector only is concerned about maximum temperature usually, and after obtaining the maximal value of multi way temperature, post processing electric circuit only needs this road temperature is processed, therefore auctioneering circuit makes the simplicity of design of post processing electric circuit, has reduced hardware cost.
Described optical coupling isolation circuit 3 is comprised of operational amplifier U2B and U5A, opto-coupler chip U3,5V insulating power supply module U4, and C6, R11, R12, R13, C7, C8, R14, C9 are peripheral circuit.Opto-coupler chip U3 has carried out electrical isolation with rear class conservation treatment circuit and temperature collection circuit, current transformer major loop, for late-class circuit provides isolation 5V power supply 5V2.The output of amplifier U2B drives the light emitting diode of opto-coupler chip HCNR201 by R13,3,4 pin and 5,6 pin of HCNR201 are connected into symmetric form, and R12 and R14 select similar resistance usually, and the voltage signal after light-coupled isolation is the same with isolated preceding-terminal like this.The 5V2 that U4 becomes to isolate with 5V1-0V1 power conversion-0V2 power supply is the late-class circuit power supply.
Described voltage reference source circuit 4 is comprised of voltage stabilizing chip U7, U9 and operational amplifier U8A, U8B, U5B, and R22, R23, R24, R25, C11 are the peripheral circuit of amplifier.U7 output reference voltage 2.5V, identical with the R24 resistance for U8A resistance R 23, it is output as 2 times of voltages of input, i.e. 5V reference voltage.This voltage provides the 5V reference voltage for temperature acquisition filtering circuit 1, guarantees the accurate of temperature acquisition.U5B is the voltage follow pattern, output 2.5V reference voltage, and this voltage provides the 2.5V reference voltage for the stagnant chain rate of excess temperature than circuit 5.Due to temperature acquisition filtering circuit 1 and the stagnant chain rate of excess temperature than circuit 5 electrical isolation, therefore voltage reference source circuit is by two groups of voltage stabilizing chip U7 and U9 design.
The stagnant chain rate of described excess temperature is than circuit 5, be comprised of comparer U6A and LED 1, R15, R16, R17, R18, R19, R20, C10 are the peripheral circuit of comparer, and wherein R20 is the output pull-up resistor, R18 is potentiometer, and R21 is the current-limiting resistance of LED1.U6A is designed to adjustable limit value hysteresis comparator form, its in-phase input end is connected to 2.5V voltage reference 2V5 and potentiometer R18, temperature voltage signal connects the comparer inverting input after after R15, R16 are divided to OK range, regulates the threshold value that R18 can regulate hysteresis comparator.When the comparer output low level, LED1 lights, indication excess temperature malfunction.Than general comparator design, the thresholding width of hysteresis comparator can be avoided near the frequent protection action the excess temperature limit value.The excess temperature fault level signal OVTMP of excess temperature hysteresis comparator output is carried out hardware logic with current transformer driving signal and computing just can be blocked rapidly driving pulse, thereby stop current transformer, complete the protection process.
Claims (6)
1. a current transformer excess temperature detects and holding circuit, it is characterized in that, comprising: temperature acquisition filtering circuit (1), auctioneering circuit (2), optical coupling isolation circuit (3), voltage reference source circuit (4), the stagnant chain rate of excess temperature are than circuit (5); Wherein, voltage reference source circuit (4) is connected than circuit (5) with the stagnant chain rate of excess temperature with temperature acquisition filtering circuit (1) respectively; Temperature acquisition filtering circuit (1), auctioneering circuit (2), optical coupling isolation circuit (3), the stagnant chain rate of excess temperature are connected successively than circuit (5).
2. circuit according to claim 1, is characterized in that, described temperature acquisition filtering circuit (1) is comprised of 3 road identical collection filtering circuits, and wherein, every road all is comprised of 5V voltage-reference, thermistor, sampling resistor and RC filtering circuit.
3. circuit according to claim 1, it is characterized in that, described auctioneering circuit (2) is comprised of with diode and the operational amplifier that is connected into the voltage follower circuit form 3 output terminals, and 3 output terminals are connected to public output and are connected to over the ground resistance.
4. circuit according to claim 1, is characterized in that, described optical coupling isolation circuit (3) is comprised of 2 operational amplifiers, 1 opto-coupler chip and 1 5V insulating power supply module.
5. circuit according to claim 1, is characterized in that, described voltage reference source circuit (4) is comprised of 2 voltage stabilizing chips and 2 operational amplifiers.
6. circuit according to claim 1, is characterized in that, the stagnant chain rate of described excess temperature is comprised of 1 comparer and 1 diode than circuit (5); Comparator design becomes adjustable limit value hysteresis comparator form, and the in-phase input end of comparer is connected to 2.5V voltage reference and potentiometer, the temperature voltage signal of anti-phase input termination front stage circuits output; Be connected to light emitting diode between the output terminal of comparer and 5V power supply.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201320307503 CN203274949U (en) | 2013-05-30 | 2013-05-30 | Over-temperature detection and protection circuit of current transformer |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201320307503 CN203274949U (en) | 2013-05-30 | 2013-05-30 | Over-temperature detection and protection circuit of current transformer |
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| Publication Number | Publication Date |
|---|---|
| CN203274949U true CN203274949U (en) | 2013-11-06 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN 201320307503 Expired - Fee Related CN203274949U (en) | 2013-05-30 | 2013-05-30 | Over-temperature detection and protection circuit of current transformer |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112799445A (en) * | 2020-12-29 | 2021-05-14 | 珠海格力电器股份有限公司 | Temperature processing system and method of frequency converter |
| CN114414879A (en) * | 2022-03-30 | 2022-04-29 | 山东丝琳医药科技有限公司 | Overcurrent detection system, method and device |
-
2013
- 2013-05-30 CN CN 201320307503 patent/CN203274949U/en not_active Expired - Fee Related
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112799445A (en) * | 2020-12-29 | 2021-05-14 | 珠海格力电器股份有限公司 | Temperature processing system and method of frequency converter |
| CN114414879A (en) * | 2022-03-30 | 2022-04-29 | 山东丝琳医药科技有限公司 | Overcurrent detection system, method and device |
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| 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: 20131106 Termination date: 20150530 |
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| EXPY | Termination of patent right or utility model |