CN218499125U - Direct current signal isolation acquisition circuit - Google Patents
Direct current signal isolation acquisition circuit Download PDFInfo
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- CN218499125U CN218499125U CN202222681296.0U CN202222681296U CN218499125U CN 218499125 U CN218499125 U CN 218499125U CN 202222681296 U CN202222681296 U CN 202222681296U CN 218499125 U CN218499125 U CN 218499125U
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Abstract
The utility model discloses a direct current signal isolation acquisition circuit, which comprises an EMC protection circuit, a divider resistance circuit, an RC low-pass filter circuit, an isolation operational amplifier circuit and an operational amplifier conditioning circuit which are connected in series in sequence; the EMC protection circuit is used for performing electromagnetic compatibility protection on a post-stage circuit; the voltage dividing resistor circuit is used for dividing the input voltage signal into an input range of the isolation operational amplifier circuit or converting the input current signal into a voltage signal; the RC low-pass filter circuit is used for filtering high-frequency interference in the signal; the isolation operational amplifier circuit is used for isolation sampling of signals; the operational amplifier conditioning circuit is used for conditioning the sampling signal. The utility model discloses have higher electrical isolation and better sampling precision, workable in the electromagnetic environment of complicacy with satisfy relevant EMC test performance index.
Description
Technical Field
The utility model relates to a direct current signal keeps apart acquisition circuit belongs to relay protection technical field.
Background
In the field of relay protection, in order to improve the anti-interference performance and reliability of a system, an electrical isolation technology is generally adopted for signal acquisition, and the current common direct-current isolation circuits mainly comprise the following two types: 1. the linear optical coupler is adopted for isolation, the linear characteristic of a signal in the method is easily influenced by the transmission characteristic and the temperature drift of the optical coupler, and the isolation degree of the linear optical coupler is not high; 2. by adopting the direct current Hall element, the precision of the element is easily influenced by temperature, and the individual volume is large and is not easy to design and use.
The two isolation modes are limited by the characteristics of the isolation modes, so that the sampling precision of signals is influenced, the two isolation modes cannot directly work in a complex electromagnetic environment, and related EMC (electromagnetic compatibility) test performance indexes cannot be met.
SUMMERY OF THE UTILITY MODEL
The utility model provides a direct current signal keeps apart acquisition circuit has solved the problem that reveals in the background art.
In order to solve the technical problem, the utility model discloses the technical scheme who adopts is:
a direct current signal isolation acquisition circuit comprises an EMC protection circuit, a voltage division resistor circuit, an RC low-pass filter circuit, an isolation operational amplifier circuit and an operational amplifier conditioning circuit which are sequentially connected in series; the EMC protection circuit is used for performing electromagnetic compatibility protection on a rear-stage circuit; the voltage dividing resistor circuit is used for dividing the input voltage signal into an input range of the isolation operational amplifier circuit or converting the input current signal into a voltage signal; the RC low-pass filter circuit is used for filtering high-frequency interference in the signal; the isolation operational amplifier circuit is used for isolation sampling of signals; the operational amplifier conditioning circuit is used for conditioning the sampling signal.
The EMC protection circuit comprises a positive signal wire, a negative signal wire, a piezoresistor RV1, a piezoresistor RV2, a piezoresistor RV3, a safety capacitor CY1, a safety capacitor CY2, a magnetic bead L1 and a magnetic bead L2;
one end of the positive signal line is a positive input end VIN + of the direct-current signal isolation acquisition circuit, and the other end of the positive signal line is connected with a positive input end of the divider resistance circuit; one end of the negative signal line is a negative input end VIN-of the direct current signal isolation acquisition circuit, and the other end of the negative signal line is connected with a negative input end of the divider resistance circuit;
varistor RV1 is connected between positive input end VIN + and ground, ann's rule electric capacity CY1 is connected between positive input end VIN + and ground, varistor RV2 is connected between negative input end VIN-and ground, ann's rule electric capacity CY2 is connected between negative input end VIN-and ground, varistor RV3 is connected between positive input end VIN + and negative input end VIN-, magnetic bead L1 concatenates on the positive signal line, and be close to divider resistance circuit, magnetic bead L2 concatenates on the negative signal line, and be close to divider resistance circuit.
The voltage division resistor circuit comprises a resistor R1 and a resistor R2; the positive input end of bleeder resistance circuit is regarded as to resistance R1's one end, connects EMC protection circuit's positive output end, and resistance R1's the other end is regarded as bleeder resistance circuit's positive output end, connects RC low pass filter circuit's positive input end and resistance R2's one end, and resistance R2's the other end is regarded as bleeder resistance circuit's negative input end and negative output end, connects EMC protection circuit's negative output end and RC low pass filter circuit's negative input end respectively.
The RC low-pass filter circuit is a second-order passive low-pass filter circuit.
The RC low-pass filter circuit comprises a resistor R3, a resistor R4, a capacitor C1 and a capacitor C2; resistance R3's one end is as RC low pass filter circuit's positive input end, connect divider resistance circuit's positive output end, electric capacity C1's one end and resistance R4's one end are connected to resistance R3's the other end, resistance R4's the other end is as RC low pass filter circuit's positive output end, connect the positive input end of keeping apart the operational amplifier circuit and electric capacity C2's one end, electric capacity C1's the other end is as RC low pass filter circuit's negative input end, connect divider resistance circuit's negative output end and electric capacity C2's the other end, electric capacity C2's the other end is as RC low pass filter circuit's negative output end, connect the negative input end of keeping apart the operational amplifier circuit.
The isolation operational amplifier circuit comprises an isolation operational amplifier and an isolation power supply module for supplying power to the isolation operational amplifier.
The isolation power supply module is a voltage-stabilizing DC/DC power supply module.
The operational amplifier conditioning circuit comprises a resistor R5, a resistor R6, a resistor R7, a resistor R8 and a first operational amplifier A1; the positive output end of keeping apart the operational amplifier circuit is connected to resistance R5's one end, the positive input end of first operational amplifier A1 and the one end of resistance R7 are connected to resistance R5's the other end, direct current bias voltage is connected to resistance R7's the other end, the negative output end of keeping apart the operational amplifier circuit is connected to resistance R6's one end, first operational amplifier A1's negative input end and resistance R8's one end are connected to resistance R6's the other end, first operational amplifier A1's output is connected to resistance R8's the other end, the output of first operational amplifier A1 is as the output that the conditioning circuit was put to fortune.
If the output voltage of the first operational amplifier A1 does not need to be subjected to direct current bias, the end part connected with the direct current bias voltage is grounded.
The utility model discloses the beneficial effect who reaches: the utility model discloses a divider resistance circuit can realize the electrical isolation and the high accuracy sampling of signal with keeping apart fortune discharge circuit, can improve the anti-electromagnetic interference nature of circuit greatly through EMC protection circuit, and the EMC performance of improvement circuit can satisfy each item EMC experiment test performance index to the circuit is simple reliable easily promotes.
Drawings
Fig. 1 is a block diagram of the circuit structure of the present invention;
fig. 2 is a detailed circuit diagram of the present invention.
Detailed Description
The present invention will be further described with reference to the accompanying drawings. The following examples are only for illustrating the technical solutions of the present invention more clearly, and the protection scope of the present invention is not limited thereby.
As shown in fig. 1, a dc signal isolation and collection circuit includes an EMC protection circuit, a voltage dividing resistor circuit, an RC low-pass filter circuit, an isolation operational amplifier circuit, and an operational amplifier conditioning circuit, which are connected in series in sequence. The EMC protection circuit is used for performing electromagnetic compatibility protection on a post-stage circuit; the voltage dividing resistor circuit is used for dividing an input voltage signal into an input range of the isolation operational amplifier circuit or converting an input current signal into a voltage signal; the RC low-pass filter circuit is used for filtering high-frequency interference in the signal; the isolation operational amplifier circuit is used for isolating and sampling signals; the operational amplifier conditioning circuit is used for conditioning the sampling signal.
The direct current signal isolation acquisition circuit can realize electrical isolation and high-precision sampling of signals through the divider resistance circuit and the isolation operational amplifier circuit, can greatly improve the anti-electromagnetic interference performance of the circuit through the EMC protection circuit, improves the EMC performance of the circuit, can meet various EMC experimental test performance indexes, and is simple, reliable and easy to popularize.
The specific structure of each circuit is shown in fig. 2. EMC protection circuit includes positive signal line, negative signal line, piezo-resistor RV1, piezo-resistor RV2, piezo-resistor RV3, ann rule electric capacity CY1, ann rule electric capacity CY2, magnetic bead L1 and magnetic bead L2.
One end of the positive signal line is a positive input end VIN + of the direct-current signal isolation acquisition circuit, and the other end of the positive signal line is connected with a positive input end of the divider resistance circuit; one end of the negative signal line is a negative input end VIN-of the direct current signal isolation acquisition circuit, and the other end of the negative signal line is connected with a negative input end of the divider resistance circuit.
The voltage dependent resistor RV1 is connected between a positive input end VIN + and the ground, the safety capacitor CY1 is connected between the positive input end VIN + and the ground, the voltage dependent resistor RV2 is connected between a negative input end VIN-and the ground, the safety capacitor CY2 is connected between the negative input end VIN-and the ground, and common mode interference in the circuit is suppressed through the voltage dependent resistor RV1, the voltage dependent resistor RV2, the safety capacitor CY1 and the safety capacitor CY 2. The piezoresistor RV3 is connected between the positive input end VIN + and the negative input end VIN-, and differential mode interference in the circuit is inhibited through the piezoresistor RV 3. Magnetic bead L1 concatenates on positive signal line to be close to divider resistance circuit, magnetic bead L2 concatenates on the negative signal line, and is close to divider resistance circuit, through the interference of the high frequency conduction signal in the magnetic bead suppression circuit.
According to the practical application occasions, the appropriate piezoresistor RV1, the piezoresistor RV2, the piezoresistor RV3, the safety capacitor CY1, the safety capacitor CY2, the magnetic bead L1 and the magnetic bead L2 can be selected, common mode interference, differential mode interference and partial high-frequency conducted interference in a complex electromagnetic environment can be effectively inhibited, the electromagnetic interference resistance of the circuit can be greatly improved through the EMC protection circuit, the EMC performance of the circuit is improved, various EMC experiment indexes can be met, and therefore the reliable operation of the circuit is guaranteed.
The voltage division resistor circuit comprises a resistor R1 and a resistor R2; the positive input end of bleeder resistance circuit is regarded as to resistance R1's one end, connects EMC protection circuit's positive output end, and resistance R1's the other end is regarded as bleeder resistance circuit's positive output end, connects RC low pass filter circuit's positive input end and resistance R2's one end, and resistance R2's the other end is regarded as bleeder resistance circuit's negative input end and negative output end, connects EMC protection circuit's negative output end and RC low pass filter circuit's negative input end respectively.
In the divider resistance circuit, can use the mode of a plurality of resistances series connection and parallelly connected that can tear suitable resistance into with resistance R1 and resistance R2 according to the voltage class of using, can satisfy the requirement that the resistance derates on the one hand, on the other hand can improve divider resistance's precision in order to reduce measuring error.
According to the practical application occasions, the input range of the sampling voltage can be adjusted by selecting the proper resistor R1 and the proper resistor R2 so as to be suitable for the application occasions with different voltage levels, and the signal after voltage division by the resistors can meet the sampling range of the rear-stage isolation operational amplifier.
The RC low-pass filter circuit is a second-order passive low-pass filter circuit and comprises a resistor R3, a resistor R4, a capacitor C1 and a capacitor C2; resistance R3's one end is as RC low pass filter circuit's positive input end, connect divider resistance circuit's positive output end, electric capacity C1's one end and resistance R4's one end are connected to resistance R3's the other end, resistance R4's the other end is as RC low pass filter circuit's positive output end, connect the positive input end of keeping apart the operational amplifier circuit and electric capacity C2's one end, electric capacity C1's the other end is as RC low pass filter circuit's negative input end, connect divider resistance circuit's negative output end and electric capacity C2's the other end, electric capacity C2's the other end is as RC low pass filter circuit's negative output end, connect the negative input end of keeping apart the operational amplifier circuit.
In practical applications, R3= R4= R, and C1= C2= C are usually taken, and the transfer function of the available second-order RC low-pass filter circuit is:
the amplitude-frequency characteristic obtained from the transfer function is:
the amplitude-frequency response-3 dB is usually taken as a cut-off frequency point, and the characteristic angular frequency can be obtained at the time
The omega value is taken according to the actually required cut-off frequency point, the capacitor C is a capacitor at nF level, the value of the resistor R can be obtained by substituting a formula, for example, the-3 dB cut-off frequency is 100Hz, the capacitor is 10nF, and the resistance value of the resistor R is 60k by substituting the formula.
The isolation operational amplifier circuit comprises an isolation operational amplifier U1 and an isolation power supply module U2 for supplying power to the isolation operational amplifier U1. The isolation operational amplifier U1 generally has higher isolation voltage and extremely low gain error, for example, a commonly used AMC1200B chip of TI company, the isolation voltage of the chip is as high as 4000V, the accuracy of the gain error can reach 0.5%, and the chip has a good temperature drift coefficient, and is little affected by temperature, under the complex environment of high voltage and high interference, the isolation sampling of signals can be completed, the high-accuracy sampling of signals can be realized by matching with a high-accuracy divider resistor, the isolation power module U2 generally adopts a voltage-stabilizing DC/DC power module, and the output direct-current isolation voltage is used by the isolation operational amplifier U1.
The operational amplifier conditioning circuit comprises a resistor R5, a resistor R6, a resistor R7, a resistor R8 and a first operational amplifier A1; keep apart the positive output of operational amplifier circuit is connected to resistance R5's one end, the positive input of A1 and the one end of resistance R7 are put to first fortune is connected to resistance R5's the other end, direct current bias voltage VREF is connected to resistance R7's the other end, the negative output of keeping apart the operational amplifier circuit is connected to resistance R6's one end, first fortune is put A1's negative input end and resistance R8's one end is connected to resistance R6's the other end, first fortune is put A1's output is connected to resistance R8's the other end, the output that conditioning circuit was put as fortune to first fortune's output.
The operational amplifier conditioning circuit converts a differential signal output by the isolation operational amplifier U1 into a single-ended signal for sampling by a rear-stage ADC (analog to digital converter), vp and Vn in the diagram are differential voltage signals output by the isolation operational amplifier U1, and according to the characteristics of the operational amplifier, R5= R6 and R7= R8 are selected to obtain the output voltage of the first operational amplifier A1
When the output voltage of the first operational amplifier A1 does not need to be dc biased, the end connected to the dc bias voltage VREF is usually directly grounded.
The first operational amplifier A1 can select a double-rail power supply according to actual measurement requirements, when direct-current voltage or current negative value collection is not considered, VOP + can be directly connected with a power supply VCC, VOP-is grounded, circuit design can be simplified, cost is reduced, the gain of a sampling signal can be adjusted by adjusting the values of R6 and R8 so as to meet the input range of rear-end ADC sampling, the conditioned signal can be directly collected by the rear-end ADC, and design of a rear-end circuit is simplified.
The direct-current signal isolation acquisition circuit has high electrical isolation and sampling precision, and can work in a complex electromagnetic environment and meet related EMC test performance indexes.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, a plurality of modifications and variations can be made without departing from the technical principle of the present invention, and these modifications and variations should also be considered as the protection scope of the present invention.
Claims (9)
1. A direct current signal isolation acquisition circuit is characterized by comprising an EMC protection circuit, a voltage division resistor circuit, an RC low-pass filter circuit, an isolation operational amplifier circuit and an operational amplifier conditioning circuit which are sequentially connected in series; the EMC protection circuit is used for performing electromagnetic compatibility protection on a post-stage circuit; the voltage dividing resistor circuit is used for dividing the input voltage signal into an input range of the isolation operational amplifier circuit or converting the input current signal into a voltage signal; the RC low-pass filter circuit is used for filtering high-frequency interference in the signal; the isolation operational amplifier circuit is used for isolating and sampling signals; the operational amplifier conditioning circuit is used for conditioning the sampling signal.
2. The isolated acquisition circuit of claim 1, wherein the EMC protection circuit comprises a positive signal line, a negative signal line, a piezoresistor RV1, a piezoresistor RV2, a piezoresistor RV3, a safety capacitor CY1, a safety capacitor CY2, a magnetic bead L1 and a magnetic bead L2;
one end of the positive signal line is a positive input end VIN + of the direct-current signal isolation acquisition circuit, and the other end of the positive signal line is connected with a positive input end of the divider resistance circuit; one end of the negative signal line is a negative input end VIN-of the direct current signal isolation acquisition circuit, and the other end of the negative signal line is connected with a negative input end of the divider resistance circuit;
varistor RV1 is connected between positive input end VIN + and ground, ann's rule electric capacity CY1 is connected between positive input end VIN + and ground, varistor RV2 is connected between negative input end VIN-and ground, ann's rule electric capacity CY2 is connected between negative input end VIN-and ground, varistor RV3 is connected between positive input end VIN + and negative input end VIN-, magnetic bead L1 concatenates on the positive signal line, and be close to divider resistance circuit, magnetic bead L2 concatenates on the negative signal line, and be close to divider resistance circuit.
3. The isolated acquisition circuit of claim 1, wherein the voltage dividing resistor circuit comprises a resistor R1 and a resistor R2; resistance R1's one end is as divider resistance circuit's positive input end, connects EMC protection circuit's positive output end, and resistance R1's the other end is as divider resistance circuit's positive output end, connects RC low pass filter circuit's positive input end and resistance R2's one end, and resistance R2's the other end is as divider resistance circuit's negative input end and negative output end, connects EMC protection circuit's negative output end and RC low pass filter circuit's negative input end respectively.
4. The isolated acquisition circuit for the direct current signal according to claim 1, wherein the RC low-pass filter circuit is a second-order passive low-pass filter circuit.
5. The direct current signal isolation acquisition circuit of claim 4, wherein the RC low-pass filter circuit comprises a resistor R3, a resistor R4, a capacitor C1 and a capacitor C2; resistance R3's one end is as RC low pass filter circuit's positive input end, connect divider resistance circuit's positive output end, electric capacity C1's one end and resistance R4's one end are connected to resistance R3's the other end, resistance R4's the other end is as RC low pass filter circuit's positive output end, connect the positive input end of keeping apart the operational amplifier circuit and electric capacity C2's one end, electric capacity C1's the other end is as RC low pass filter circuit's negative input end, connect divider resistance circuit's negative output end and electric capacity C2's the other end, electric capacity C2's the other end is as RC low pass filter circuit's negative output end, connect the negative input end of keeping apart the operational amplifier circuit.
6. The isolated acquisition circuit of claim 1 wherein the isolated operational amplifier circuit comprises an isolated operational amplifier and an isolated power module for powering the isolated operational amplifier.
7. The isolated DC signal acquisition circuit of claim 6, wherein the isolated power supply module is a regulated DC/DC power supply module.
8. The direct current signal isolation acquisition circuit of claim 1, wherein the operational amplifier conditioning circuit comprises a resistor R5, a resistor R6, a resistor R7, a resistor R8 and a first operational amplifier A1; the positive output end of keeping apart the operational amplifier circuit is connected to resistance R5's one end, the positive input end of first operational amplifier A1 and the one end of resistance R7 are connected to resistance R5's the other end, direct current bias voltage is connected to resistance R7's the other end, the negative output end of keeping apart the operational amplifier circuit is connected to resistance R6's one end, first operational amplifier A1's negative input end and resistance R8's one end are connected to resistance R6's the other end, first operational amplifier A1's output is connected to resistance R8's the other end, the output of first operational amplifier A1 is as the output that the conditioning circuit was put to fortune.
9. The isolated acquisition circuit of claim 8, wherein if no dc bias is required on the output voltage of the first operational amplifier A1, the end connected to the dc bias voltage is grounded.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202222681296.0U CN218499125U (en) | 2022-10-12 | 2022-10-12 | Direct current signal isolation acquisition circuit |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202222681296.0U CN218499125U (en) | 2022-10-12 | 2022-10-12 | Direct current signal isolation acquisition circuit |
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| CN218499125U true CN218499125U (en) | 2023-02-17 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN202222681296.0U Active CN218499125U (en) | 2022-10-12 | 2022-10-12 | Direct current signal isolation acquisition circuit |
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| CN (1) | CN218499125U (en) |
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- 2022-10-12 CN CN202222681296.0U patent/CN218499125U/en active Active
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