CN210243737U - Three-phase intermediate frequency voltage overvoltage protection circuit for induction heating power supply - Google Patents
Three-phase intermediate frequency voltage overvoltage protection circuit for induction heating power supply Download PDFInfo
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- CN210243737U CN210243737U CN201921119406.6U CN201921119406U CN210243737U CN 210243737 U CN210243737 U CN 210243737U CN 201921119406 U CN201921119406 U CN 201921119406U CN 210243737 U CN210243737 U CN 210243737U
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Abstract
The utility model provides an induction heating is three-phase intermediate frequency voltage overvoltage protection circuit for power, the purpose is solved current sampling mode and is influenced the technical problem of normal production because of generating heat and anti jamming capability is poor, the reliability is not good and production facility mistake is shut down. The overvoltage protection circuit comprises two branches which are identical in structure and formed by sequentially connecting a voltage reduction differential sampling circuit, an electronic rectifying circuit, a direct-current voltage amplification filter circuit and a voltage comparison circuit in series, and an OR gate logic circuit of which the input end is respectively connected to the output ends of the two branches. The utility model discloses a two way structures, no magnetism coupling ring festival in the work, the direct electronic type coupling of circuit at different levels, sampling response speed is fast, and interference immunity is good, and the isolation is high, and is reliable and stable, small in size, can adapt to the complicated condition of load operating mode better, effectively avoid the malfunction.
Description
Technical Field
The utility model belongs to the technical field of induction power supply protection circuit technique and specifically relates to a three-phase intermediate frequency voltage overvoltage protection circuit for induction heating power supply is related to.
Background
In the vacuum evaporation equipment, a high-power induction heating power supply needs to be matched. The power supply uses a high-power IGBT as a core element and is better in energy efficiency and reliability.
The load of the induction heating power supply is a graphite crucible, metal materials in the crucible are melted in an electromagnetic eddy current induction mode to form metal steam, and a layer of metal film is evaporated on the surface of the plastic base material rotating at a high speed. Compared with the traditional heating evaporation equipment, the induction type heating power supply has the advantages of short heating time, high heat efficiency, high film forming quality and the like. In practical application, the output of the induction heating power supply is three-phase, the working frequency is between 10 and 20KHz, and a rapid and reliable three-phase intermediate frequency overvoltage detection circuit is needed to avoid inconsistent metal melting state in the crucible after overvoltage is output.
The existing three-phase overvoltage detection circuit generally adopts a transformer step-down sampling mode, and a sampling signal is obtained after three-phase transformer step-down → diode rectification → filtering, so that the mode has the advantages of large volume, general sampling response speed and large heat generation in intermediate frequency application. The output interference of the induction heating power supply is large, and the frequency is intermediate frequency. Therefore, in the process of adopting the transformer, equipment is often stopped by mistake due to the heat generated by the transformer, and normal production is influenced.
Disclosure of Invention
To the above situation, for overcoming prior art's defect, the utility model provides an induction heating is three-phase intermediate frequency voltage overvoltage protection circuit for power has solved the sampling mode and has influenced normal production's technical problem because of generating heat and the interference killing feature is poor, the reliability is not good and lead to production facility mistake to shut down.
In order to achieve the above object, the utility model provides a following technical scheme:
a three-phase intermediate frequency voltage overvoltage protection circuit for an induction heating power supply comprises:
the first branch circuit is formed by sequentially connecting a voltage reduction differential sampling circuit, an electronic rectifying circuit, a direct current voltage amplification filtering circuit and a voltage comparison circuit in series;
the second branch circuit has the same structure as the first branch circuit;
and two input ends of the OR gate logic circuit are respectively connected to the output end of the first branch voltage comparison circuit and the output end of the second branch voltage comparison circuit, and the output ends output comparison results by level signals.
Further, the buck differential sampling circuit comprises:
the input end of the first voltage reduction resistor is connected to the U phase or the V phase of the power supply to be detected;
the input end of the second voltage reduction resistor is connected to the V phase or the W phase of the power supply to be detected;
the inverting input end of the first operational amplifier is connected to the output end of the first step-down resistor, the homodromous input end of the first operational amplifier is connected to the output end of the second step-down resistor, and the output end of the first operational amplifier is the output end of the step-down differential sampling circuit;
and two ends of the feedback resistor are bridged with the reverse input end and the output end of the first operational amplifier.
Further, the electronic rectification circuit includes:
the reverse input end of the second operational amplifier is connected to the output end of the first operational amplifier;
and two ends of the rectifying loop are bridged with the reverse input end and the output end of the second operational amplifier.
Further, the rectifying circuit includes:
a first rectifying diode;
the second rectifier diode is connected with the first rectifier diode in series;
the first resistor is connected in parallel with the series circuit of the first rectifying diode and the second rectifying diode;
the parallel common end on the cathode side of the diode is connected to the reverse input end of the second operational amplifier, and the parallel common end on the anode side of the diode is the output end of the electronic rectifying circuit.
Further, the dc voltage amplifying and filtering circuit includes:
the reverse input end of the third operational amplifier is connected to the parallel common end on one side of the anode of the diode, and the output end of the third operational amplifier is the output end of the direct-current voltage amplifying and filtering circuit;
and two ends of the second resistor are bridged with the reverse input end and the output end of the third operational amplifier.
Further, the first branch or the second branch further comprises:
the feedback capacitor is connected in parallel with the feedback resistor;
and the smoothing filter capacitor is connected in parallel with the second resistor.
Further, the voltage comparison circuit includes:
the homodromous input end of the fourth operational amplifier is connected to the output end of the third operational amplifier, and the output end of the fourth operational amplifier is the output end of the voltage comparison circuit;
the threshold circuit is composed of two resistors connected in series, one end of the threshold circuit is grounded, and the other end of the threshold circuit is connected to the fourth operational amplifier positive power supply;
the inverting input terminal of the fourth operational amplifier is connected between the two resistors of the threshold circuit.
Further, the first branch or the second branch further comprises:
the grounding bias resistors are respectively connected to the homodromous input ends of the operational amplifier, the second operational amplifier and the third operational amplifier;
and the balance resistors are respectively connected between the output end of the voltage reduction differential sampling circuit and the input end of the electronic rectifying circuit, between the output end of the electronic rectifying circuit and the input end of the direct-current voltage amplification filter circuit, and between the output end of the direct-current voltage amplification filter circuit and the input end of the voltage comparison circuit.
Furthermore, the or gate logic circuit is formed by connecting two isolation diodes in series, and the input ends of the isolation diodes are respectively connected to the fourth operational amplifier output end in the first branch and the fourth operational amplifier output end in the second branch; a level signal output point is arranged between the two isolation diodes.
Further, the first branch or the second branch further comprises:
the current-limiting isolation resistors are respectively connected between the output end of the voltage comparison circuit and the isolation diode of the OR gate logic circuit;
and one end of the pull-down resistor is connected to the front of the level signal output point, and the other end of the pull-down resistor is grounded.
The utility model adopts two branches to respectively sample the high-voltage alternating voltage signal of the power source to be detected U/V, V/W, then carries out voltage reduction and differential amplification, and outputs a low-voltage alternating voltage signal; then rectifying the low-voltage alternating-current voltage signal and outputting the rectified low-voltage alternating-current voltage signal as a direct-current pulsating voltage signal; finally, a level signal is output after amplification and comparison so as to determine whether overvoltage exists. In the working process, no magnetic coupling loop is arranged, each stage of circuit is directly coupled in an electronic mode, the sampling response speed is high, and the anti-interference performance is good due to the adoption of the double-unit differential input operational amplifier circuit. The electric property is more reliable and more stable, and small in size can better adapt to the complicated condition of load working condition, effectively avoids the malfunction. The utility model discloses the sampling voltage scope is three-phase 10HZ ~30KHZ, 5V ~500V alternating voltage, and the isolation is high, and the commonality is strong, the feedback sampling circuit of fungible transformer sampling type.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.
Fig. 1 is a schematic structural diagram of the present invention.
Fig. 2 is a schematic structural diagram of an embodiment of the present invention.
Fig. 3 is the utility model discloses application embodiment's step-down differential sampling circuit's schematic structure.
Fig. 4 is a schematic structural diagram of an electronic rectification circuit in an embodiment of the present invention.
Fig. 5 is a schematic structural diagram of a dc voltage amplifying and filtering circuit according to an embodiment of the present invention.
Fig. 6 is a schematic structural diagram of a voltage comparison circuit in an embodiment of the present invention.
Fig. 7 is a schematic structural diagram of an or gate logic circuit in an embodiment of the present invention.
Reference numerals: 100. the circuit comprises a first branch circuit, a second branch circuit, a 300 OR gate logic circuit, a 1 step-down differential sampling circuit, a 11 first step-down resistor, a 12 second step-down resistor, a 13 first operational amplifier, a 14 feedback resistor, a 15 feedback capacitor, a 16 ground bias resistor, a 2 electronic rectifying circuit, a 21 second operational amplifier, a 22 ground bias resistor, a 23 rectifying loop, 231 first rectifying diode, 232 second rectifying diode, 233 first resistor, 3 DC voltage amplifying and filtering circuit, 31 third operational amplifier, 32 ground bias resistor, 33 second resistor, 34 smoothing and filtering capacitor, 4 voltage comparison circuit, 41 fourth operational amplifier, 42 threshold circuit, 421.422 resistor, 51.52 isolation diode, 61.62.63 balancing resistor, 71.72 current limiting and isolation resistor, and 8 pull-down resistor.
Detailed Description
In the following, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the claimed embodiments. Accordingly, the drawings and description are to be regarded as illustrative in nature, and not as restrictive.
Furthermore, the terms "first", "second", "third", "fourth" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", "third", "fourth" may explicitly or implicitly include one or more of the features. In the description of the embodiments of the present application, "a plurality" means two or more unless specifically defined otherwise.
In order to simplify the disclosure of the embodiments of the present application, the components and arrangements of the specific examples are described below. Of course, they are merely examples and are not intended to limit embodiments of the present application. In addition, the examples provided herein provide examples of various specific materials, but one of ordinary skill in the art will recognize the use of other materials.
Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.
As shown in fig. 1, the utility model provides an application embodiment provides an induction heating is three-phase intermediate frequency voltage overvoltage protection circuit for power, include:
the first branch circuit 100 is formed by sequentially connecting a voltage reduction differential sampling circuit 1, an electronic rectifying circuit 2, a direct-current voltage amplification filtering circuit 3 and a voltage comparison circuit 4 in series;
a second branch 200 having the same structure as the first branch 100;
the two input terminals of the or gate logic circuit 300 are respectively connected to the output terminal a of the voltage comparison circuit of the first branch 100 and the output terminal B of the voltage comparison circuit of the second branch 200, and the output terminals output the comparison result as level signals.
The first branch circuit 100 and the second branch circuit 200 respectively collect three-phase intermediate-frequency high-voltage alternating-current voltage signals of the power source U, V, W to be detected. The voltage reduction differential sampling circuit 1 in the branch circuit reduces voltage of a high-voltage alternating-current voltage signal of an intermediate frequency U, V, W phase → performs differential amplification and outputs the low-voltage alternating-current voltage signal, the electronic rectification circuit 2 rectifies the two low-voltage alternating-current voltage signals and outputs a direct-current pulsating voltage signal, the input direct-current pulsating voltage signal is amplified → compared through the direct-current voltage amplification filter circuit 3, the voltage comparison circuit 4 and the or gate logic circuit 300 in sequence, and a level signal is output to prompt whether any phase of U, V, W has overvoltage or not.
Since the first branch 100 and the second branch 200 have the same structure, the first branch 100 is only used as an example to describe the differential voltage drop sampling circuit 1, the electronic rectification circuit 2, the dc voltage amplification filter circuit 3, and the voltage comparison circuit 4.
As shown in fig. 3, the step-down differential sampling circuit includes:
the input of the first voltage-reducing resistor 11 is connected to the U-phase of the power source to be tested (in the second branch 200, the input of the first voltage-reducing resistor is connected to the V-phase of the power source to be tested).
The input of the second step-down resistor 12 is connected to the V-phase of the power source to be tested (in the second branch 200, the input of the second step-down resistor is connected to the W-phase of the power source to be tested).
In this embodiment, the first voltage-reducing resistor 11 and the second voltage-reducing resistor 12 are metal film resistors with 0.1% precision.
The inverting input terminal of the first operational amplifier 13 is connected to the output terminal of the first step-down resistor 11, the inverting input terminal thereof is connected to the output terminal of the second step-down resistor 12, and the output terminal thereof is the output terminal of the step-down differential sampling circuit.
And two ends of the feedback resistor 14 are connected across the inverting input end and the output end of the first operational amplifier 13.
And the feedback capacitor 15 is connected in parallel with the feedback resistor 14.
The ground bias resistor 16 is connected to the same-direction input end of an operational amplifier 13.
In operation, the first voltage-reducing resistor 11 and the second voltage-reducing resistor 12 attenuate the input high-voltage ac voltage by about 100 times. The first operational amplifier 13 is responsible for forming a differential amplification part with strong anti-interference capability, and the ground bias resistor 16 provides proper bias current for the first operational amplifier 13 to stabilize the operation thereof. The feedback capacitor 15 can prevent the operational amplifier from oscillating when the input voltage is low.
As shown in fig. 4, the electronic rectifier circuit includes:
a second operational amplifier 21, the reverse input end of which is connected to the output end of the first operational amplifier; the same-direction input end of the resistor is connected with a ground bias resistor 22 which has the similar function as the ground bias resistor 16.
And the two ends of the rectifying loop 23 are connected across the reverse input end and the output end of the second operational amplifier.
Wherein, the rectification return circuit includes:
a first rectifying diode 231;
a second rectifying diode 232 connected in series with the first rectifying diode 231;
the first resistor 233 is connected in parallel to the series circuit of the first rectifying diode 231 and the second rectifying diode 232.
The parallel common terminal C at the cathode side of the diode is connected to the reverse input terminal of the second operational amplifier 21, and the parallel common terminal D at the anode side of the diode is the output terminal of the electronic rectifying circuit.
In operation, the first rectifying diode 231 and the second rectifying diode 232 connected in series form a full-wave rectifying circuit for rectifying the positive half-wave and the negative half-wave of the ac signal. By adopting the matching of the diode and the second operational amplifier 21, the voltage drop of the 0.7V tube of the diode is avoided, and the linearity of the sampling voltage is improved.
As shown in fig. 2, a balancing resistor 61 is connected between the output end of the step-down differential sampling circuit and the input end of the electronic rectifying circuit, and is used for balancing the output of the step-down differential sampling circuit and the input impedance of the electronic rectifying circuit, and the balancing resistor and the first resistor 233 form a signal proportional amplifying circuit.
As shown in fig. 5, the dc voltage amplifying and filtering circuit includes:
the inverting input terminal of the third operational amplifier 31 is connected to the parallel common terminal B on the anode side of the diode, the homodromous input terminal thereof is connected to the ground bias resistor 32, the function of the ground bias resistor is similar to that of the ground bias resistor 16, and the output terminal thereof is the output terminal of the dc voltage amplifying and filtering circuit.
And a second resistor 33, both ends of which are connected across the inverting input terminal and the output terminal of the third operational amplifier 31.
And a smoothing filter capacitor 34 connected in parallel to the second resistor 33. In this embodiment, the smoothing capacitor 33 is made of polypropylene.
As shown in fig. 2, a balancing resistor 62 is connected between the output terminal of the electronic rectifying circuit and the input terminal of the dc voltage amplifying and filtering circuit, and is used for balancing the output of the electronic rectifying circuit and the input impedance of the dc voltage amplifying and filtering circuit, and forming a signal proportional amplifying circuit with the second resistor 33.
As shown in fig. 6, the voltage comparison circuit includes:
a fourth operational amplifier 41, the same-direction input end of which is connected to the output end of the third operational amplifier 31; the output end of the voltage comparison circuit is the output end of the voltage comparison circuit.
The threshold circuit 42 is composed of two resistors 421 and 422 connected in series, and one end of the threshold circuit is grounded while the other end is connected to the positive power supply of the fourth operational amplifier 41.
The inverting input terminal of the fourth op-amp is connected between the resistor 421 and the resistor 422 in the threshold circuit 42.
As shown in fig. 2, a balance resistor 63 is connected between the output terminal of the dc voltage amplifying and filtering circuit and the input terminal of the voltage comparing circuit, and is used for the output of the dc voltage amplifying and filtering circuit and the input impedance of the voltage comparing circuit.
In this embodiment, each operational amplifier is of an LM248 model with a higher working limit parameter, so as to be suitable for industrial application.
As shown in fig. 2 and fig. 7, the or gate logic circuit 300 is formed by two isolation diodes 51 and 52 connected in series, and the input terminals of the isolation diodes are respectively connected to the fourth operational amplifier output terminal a in the first branch 100 and the fourth operational amplifier output terminal B in the second branch 200; a level signal output point K is provided between the two isolation diodes 51, 52.
A current-limiting isolation resistor 71/72 is connected between the output end of the voltage comparison circuit and the diode of the OR gate logic circuit.
A pull-down resistor 8 is connected between the two isolation diodes 51 and 52 and at the front end of the level signal output point K, and is used for stabilizing the logic state of the point K.
The first branch 100 is responsible for detecting any over-voltage of the phase voltage at the input U, V and the second branch 200 is responsible for detecting any over-voltage of the phase voltage at the input V, W. The output of the two branch circuits outputs an overvoltage signal through an OR gate logic circuit. When the voltage is normal, the level signal output point K outputs a low level, and when the voltage is over-voltage, the level signal output point K outputs a high level.
As shown in fig. 2, in actual use, the three-phase 10HZ to 30KHZ, 5V to 500V ac voltage input interface U, V, W of the induction power supply is connected to the voltage-reducing resistors 11, 12, 11a, and 12a, respectively, and the ac voltage of the power supply is divided into two paths to be subjected to voltage-reducing attenuation → rectified into direct current → amplification → filtering → comparison → logical phase or output level signals to determine whether there is overvoltage.
Claims (10)
1. A three-phase intermediate frequency voltage overvoltage protection circuit for an induction heating power supply, comprising:
the first branch circuit is formed by sequentially connecting a voltage reduction differential sampling circuit, an electronic rectifying circuit, a direct current voltage amplification filtering circuit and a voltage comparison circuit in series;
the second branch circuit has the same structure as the first branch circuit;
and two input ends of the OR gate logic circuit are respectively connected to the output end of the first branch voltage comparison circuit and the output end of the second branch voltage comparison circuit, and the output ends output comparison results by level signals.
2. The overvoltage protection circuit of claim 1, wherein the buck differential sampling circuit comprises:
the input end of the first voltage reduction resistor is connected to the U phase or the V phase of the power supply to be detected;
the input end of the second voltage reduction resistor is connected to the V phase or the W phase of the power supply to be detected;
the inverting input end of the first operational amplifier is connected to the output end of the first step-down resistor, the homodromous input end of the first operational amplifier is connected to the output end of the second step-down resistor, and the output end of the first operational amplifier is the output end of the step-down differential sampling circuit;
and two ends of the feedback resistor are bridged with the reverse input end and the output end of the first operational amplifier.
3. The overvoltage protection circuit of claim 2, wherein the electronic rectifier circuit comprises:
the reverse input end of the second operational amplifier is connected to the output end of the first operational amplifier;
and two ends of the rectifying loop are bridged with the reverse input end and the output end of the second operational amplifier.
4. The overvoltage protection circuit of claim 3, wherein the rectifying circuit comprises:
a first rectifying diode;
the second rectifier diode is connected with the first rectifier diode in series;
the first resistor is connected in parallel with the series circuit of the first rectifying diode and the second rectifying diode;
the parallel common end on the cathode side of the diode is connected to the reverse input end of the second operational amplifier, and the parallel common end on the anode side of the diode is the output end of the electronic rectifying circuit.
5. The overvoltage protection circuit of claim 4, wherein the dc voltage amplification filter circuit comprises:
the reverse input end of the third operational amplifier is connected to the parallel common end on one side of the anode of the diode, and the output end of the third operational amplifier is the output end of the direct-current voltage amplifying and filtering circuit;
and two ends of the second resistor are bridged with the reverse input end and the output end of the third operational amplifier.
6. The overvoltage protection circuit of claim 5, further comprising in the first branch or the second branch:
the feedback capacitor is connected in parallel with the feedback resistor;
and the smoothing filter capacitor is connected in parallel with the second resistor.
7. The overvoltage protection circuit of claim 5, wherein the voltage comparison circuit comprises:
the homodromous input end of the fourth operational amplifier is connected to the output end of the third operational amplifier, and the output end of the fourth operational amplifier is the output end of the voltage comparison circuit;
the threshold circuit is composed of two resistors connected in series, one end of the threshold circuit is grounded, and the other end of the threshold circuit is connected to the fourth operational amplifier positive power supply;
the inverting input terminal of the fourth operational amplifier is connected between the two resistors of the threshold circuit.
8. The overvoltage protection circuit of claim 7, further comprising in the first branch or the second branch:
the grounding bias resistors are respectively connected to the homodromous input ends of the operational amplifier, the second operational amplifier and the third operational amplifier;
and the balance resistors are respectively connected between the output end of the voltage reduction differential sampling circuit and the input end of the electronic rectifying circuit, between the output end of the electronic rectifying circuit and the input end of the direct-current voltage amplification filter circuit, and between the output end of the direct-current voltage amplification filter circuit and the input end of the voltage comparison circuit.
9. The overvoltage protection circuit of claim 7, wherein the or gate logic circuit is formed by two isolation diodes connected in series, and the input terminals of the isolation diodes are respectively connected to the fourth operational amplifier output terminal in the first branch and the fourth operational amplifier output terminal in the second branch; a level signal output point is arranged between the two isolation diodes.
10. The overvoltage protection circuit of claim 9, further comprising in the first branch or the second branch:
the current-limiting isolation resistors are respectively connected between the output end of the voltage comparison circuit and the isolation diode of the OR gate logic circuit;
and one end of the pull-down resistor is connected to the front of the level signal output point, and the other end of the pull-down resistor is grounded.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201921119406.6U CN210243737U (en) | 2019-07-17 | 2019-07-17 | Three-phase intermediate frequency voltage overvoltage protection circuit for induction heating power supply |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201921119406.6U CN210243737U (en) | 2019-07-17 | 2019-07-17 | Three-phase intermediate frequency voltage overvoltage protection circuit for induction heating power supply |
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| Publication Number | Publication Date |
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| CN210243737U true CN210243737U (en) | 2020-04-03 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN201921119406.6U Active CN210243737U (en) | 2019-07-17 | 2019-07-17 | Three-phase intermediate frequency voltage overvoltage protection circuit for induction heating power supply |
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