CN113517122B - PCB type current transformer with correction function - Google Patents
PCB type current transformer with correction function Download PDFInfo
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- CN113517122B CN113517122B CN202110420149.5A CN202110420149A CN113517122B CN 113517122 B CN113517122 B CN 113517122B CN 202110420149 A CN202110420149 A CN 202110420149A CN 113517122 B CN113517122 B CN 113517122B
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F38/00—Adaptations of transformers or inductances for specific applications or functions
- H01F38/20—Instruments transformers
- H01F38/22—Instruments transformers for single phase ac
- H01F38/28—Current transformers
- H01F38/32—Circuit arrangements
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F27/00—Details of transformers or inductances, in general
- H01F27/06—Mounting, supporting or suspending transformers, reactors or choke coils not being of the signal type
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F27/00—Details of transformers or inductances, in general
- H01F27/33—Arrangements for noise damping
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F27/00—Details of transformers or inductances, in general
- H01F27/34—Special means for preventing or reducing unwanted electric or magnetic effects, e.g. no-load losses, reactive currents, harmonics, oscillations, leakage fields
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F27/00—Details of transformers or inductances, in general
- H01F27/40—Structural association with built-in electric component, e.g. fuse
- H01F27/402—Association of measuring or protective means
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F27/00—Details of transformers or inductances, in general
- H01F27/40—Structural association with built-in electric component, e.g. fuse
- H01F27/402—Association of measuring or protective means
- H01F2027/406—Temperature sensor or protection
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Abstract
The invention discloses a PCB type current transformer with a correction function, which belongs to the technical field of current transformers and comprises a PCB type current sensing unit and a signal data processing and transmitting unit comprising an analog-to-digital conversion circuit, a microprocessor and a communication interface, wherein the PCB type current sensing unit comprises a power circuit, a signal acquisition circuit, a signal processing circuit and a temperature sensing circuit, and the signal acquisition circuit comprises M identical sub-signal acquisition circuits. The PCB type current transformer with the correction function consists of a PCB type current sensing unit and a signal data processing and transmitting unit, wherein the PCB type current sensing unit consists of a power supply circuit, M identical signal acquisition circuits, a signal processing circuit and a temperature sensing circuit, can simultaneously measure alternating current and direct current, solves the problem of saturation of the Hall current transformer due to the adoption of an iron core, and has the characteristics of small volume, light weight, low power consumption, quick response and the like.
Description
Technical Field
The invention belongs to the technical field of current transformers, and particularly relates to a PCB type current transformer with a correction function.
Background
The current transformer is a current sensor for measuring current, converts large current into a small current or voltage signal suitable for measurement, and plays a role in high-voltage isolation. With the access of high-power new energy and the large use of nonlinear load equipment, the current and the voltage of a power grid are no longer ideal working conditions of power frequency sine waves at present, the actual operating working conditions of the power grid are increasingly complex, and direct current components appear in some occasions, for example, after a converter type distributed power supply is accessed, direct current components with rated current values of a few thousandths of a current are injected into a common connection point PPC. On the other hand, the dc power supply system puts requirements on the dc current measuring device, and the actual current waveform of the dc power supply system includes two components, i.e., dc and ac ripple. At present, there are various current transformers based on different working principles, including conventional electromagnetic current transformers, electronic current transformers using low-power-consumption iron core coils or rogowski coils as sensors, electronic current transformers using shunts as sensors, hall current transformers, and current transformers using anisotropic magnetoresistance elements or giant magnetoresistance elements as sensitive elements. The traditional electromagnetic current transformer and the low-power-consumption iron core coil Rogowski coil can only measure alternating current and can not measure direct current. The electromagnetic current transformer and the low-power-consumption iron core coil can accurately measure the power frequency current, but if the measured current contains a certain direct-current component, the sensing accuracy of the electromagnetic current transformer and the low-power-consumption iron core coil is greatly reduced. The Hall current transformer can measure direct current and alternating current simultaneously, but the iron core that usually needs to gather magnetism improves Hall output sensitivity, has consequently increased the volume and the weight of mutual-inductor, has the big poor problem of linearity of consumption simultaneously. Even if alternating current is measured, current transformers such as electromagnetic current transformers, low-power-consumption iron core coils and Hall current transformers have the problem of iron core saturation, and the range is limited. The current divider can measure direct current and alternating current simultaneously, but the output signal is small, the accuracy is reduced due to heating, and meanwhile, the output needs to be isolated. The anisotropic magneto-resistance element has high sensitivity but narrow linear range, and an auxiliary coil is needed to perform presetting and resetting operations, so that the manufacturing process is complex, the volume is increased, the power consumption is large, and the giant magneto-resistance element has high sensitivity but narrow linear range. Compared with magnetic field sensors such as Hall elements, anisotropic magneto-resistance elements, giant magneto-resistance elements and the like, the tunnel magneto-resistance effect magnetic field sensor has the characteristics of better temperature stability, sensitivity, low power consumption, linearity, linear range and the like, and does not need a magnetic gathering iron core, a presetting coil and a resetting coil. The invention provides a PCB type current transformer with a correction function, which can simultaneously measure direct current and alternating current based on a tunnel magnetoresistance effect magnetic field sensor, the transformer evenly distributes a plurality of tunnel magnetoresistance effect magnetic field sensors on a PCB circular ring, a lead wire carrying the measured current passes through the circle center of the PCB circular ring, each tunnel magnetoresistance effect magnetic field sensor outputs a voltage signal in proportion to the measured current, a current sensing circuit accumulates and conditions the output voltage of the tunnel magnetoresistance effect magnetic field sensors, then outputs a current sensing signal, a temperature sensing chip arranged on the PCB circular ring provides a temperature signal at the position of the tunnel magnetoresistance effect magnetic field sensor, the current sensing signal and the temperature signal are sent to a microprocessor, the microprocessor improves the accuracy of current sensing through a temperature correction and error correction algorithm, the frequency response characteristics are improved by a correction algorithm based on a series correction transfer function. The PCB type current transformer with the correction function has the characteristics of small volume, light weight, wide range, quick response, low loss and easiness in installation, thoroughly solves the problem of saturation of iron cores of the traditional electromagnetic voltage transformer, the traditional Hall current transformer and the like, and solves the problems of temperature drift and signal response lag caused by a current sensing circuit when conditioning signals.
Disclosure of Invention
The invention aims to: in order to solve the problems of the background art, a PCB type current transformer with a calibration function is proposed.
In order to achieve the purpose, the invention adopts the following technical scheme:
a PCB type current transformer with a correction function comprises a PCB type current sensing unit and a signal data processing and transmission unit containing an analog-to-digital conversion circuit, a microprocessor and a communication interface, wherein the PCB type current sensing unit comprises a power supply circuit, a signal acquisition circuit, a signal processing circuit and a temperature sensing circuit, the signal acquisition circuit contains M identical sub-signal acquisition circuits, each sub-signal acquisition circuit contains N tunnel magneto-resistance effect magnetic field sensors with a Wheatstone full-bridge structure design, N first resistors, N second resistors, a third resistor, a fourth resistor, a fifth resistor, a first capacitor and a first operational amplifier, MxN tunnel magneto-resistance effect magnetic field sensors of the M sub-signal acquisition circuits are uniformly distributed on the circumference of the radius of a PCB, and the other end of the corresponding first resistor is connected with the inverting input end of the first operational amplifier, the analog differential positive output end of each tunnel magnetoresistance effect magnetic field sensor is connected with one end of a corresponding second resistor, the other end of the corresponding second resistor is connected with the positive phase input end of a first operational amplifier, one end of a third resistor is connected with the reverse phase input end of the first operational amplifier, the other end of the third resistor is connected with the output end of the first operational amplifier, one end of a fourth resistor is connected with the positive phase input end of the first operational amplifier, the other end of the fourth resistor is grounded, one end of a fifth resistor is connected with the output end of the first operational amplifier, the other end of the fifth resistor is connected with one end of a first capacitor and the output end of a sub-signal acquisition circuit, the other end of the first capacitor is grounded, and the signal processing circuit comprises M sixth resistor, seventh resistor, eighth resistor, ninth resistor, tenth resistor, eleventh resistor and twelfth resistor, The second capacitor, the third capacitor, the fourth capacitor, the second operational amplifier and the third operational amplifier are provided with M acquisition signal input ends and a signal output end, the M acquisition signal input ends are respectively connected with the output ends of the M sub-signal acquisition circuits one by one, each acquisition signal input end is provided with a corresponding sixth resistor, each acquisition signal input end is connected with one end of the corresponding sixth resistor, the other end of the corresponding sixth resistor is connected with the inverting input end of the second operational amplifier, and the non-inverting input end of the second operational amplifier is grounded.
As a further description of the above technical solution:
the power supply circuit is provided with three input ends of a direct current positive voltage, a direct current negative voltage, a ground signal and the like, the direct current positive voltage of the power supply circuit is 12V, the direct current negative voltage of the power supply circuit is-12V, the power supply circuit performs voltage stabilization treatment on the input direct current positive voltage and the input direct current negative voltage and then respectively supplies power to the signal acquisition circuit, the signal processing circuit and the temperature sensing circuit, two paths of analog signals are processed by the analog-to-digital conversion circuit to become digital signals, the digital signals are input into the microprocessor, and the microprocessor processes the input digital signals through a temperature correction algorithm, an error correction algorithm and a correction algorithm based on a series correction transfer function and then outputs secondary signals of the mutual inductor through a communication interface.
As a further description of the above technical solution:
the nonlinearity of the tunnel magnetoresistance effect magnetic field sensor is less than 1%.
As a further description of the above technical solution:
the communication interface adopts RS 232.
As a further description of the above technical solution:
the temperature sensing circuit is composed of a temperature sensing chip and a signal processing circuit, the temperature sensing chip is provided with a temperature analog quantity output end, the signal output end of the signal processing circuit and the temperature analog quantity output end of the temperature sensing circuit output two paths of analog signals, the magnetic field detection sensitive direction of the tunnel magnetoresistance effect magnetic field sensor is the tangential direction of the circumferential position where the tunnel magnetoresistance effect magnetic field sensor is located, each tunnel magnetoresistance effect magnetic field sensor is provided with a corresponding first resistor and a corresponding second resistor, and the analog difference negative output end of each tunnel magnetoresistance effect magnetic field sensor is connected with one end of the corresponding first resistor.
As a further description of the above technical solution:
the second capacitor and the seventh resistor are connected in parallel to the inverting input end and the output end of the second operational amplifier, one end of the eighth resistor and one end of the ninth resistor are connected with the output end of the second operational amplifier, the other end of the eighth resistor is grounded, the other end of the ninth resistor is connected with the inverting input end and the output end of the third operational amplifier, the third capacitor and the tenth resistor are connected in parallel to the inverting input end and the output end of the third operational amplifier, one end of the eleventh resistor is connected with the output end of the third operational amplifier, the other end of the eleventh resistor is connected with one end of the fourth capacitor, one end of the twelfth resistor and the signal output end of the signal processing circuit, and the other end of the fourth capacitor and the other end of the twelfth resistor are grounded.
In summary, due to the adoption of the technical scheme, the invention has the beneficial effects that:
1. the PCB type current transformer with the correction function realizes the detection, signal conditioning, error correction and frequency response characteristic correction of a current signal to be detected, can simultaneously measure alternating current and direct current, solves the saturation problem of a Hall current transformer due to the adoption of an iron core, and has the characteristics of small volume, light weight, low power consumption, quick response and the like.
2. In the invention, a plurality of tunnel magnetoresistance effect magnetic field sensors are uniformly distributed on the circumference with the radius around the conductor carrying the current to be measured, which is favorable for reducing the measurement error caused by the installation error of the PCB type current sensing unit and the conductor in the pouring process.
3. In the invention, the resistance-capacitance links in the signal acquisition circuit and the signal processing circuit can effectively inhibit noise interference, and the correction algorithm based on the series correction transfer function in the microprocessor can realize the correction of the frequency response characteristic.
4. In the invention, the PCB type current sensing unit comprises M identical sub-signal acquisition circuits, each sub-signal acquisition circuit is provided with N tunnel magneto-resistance effect magnetic field sensors, and the combined signal acquisition mode can meet the measurement of currents with different sizes under the conditions of different installation dimensions.
Drawings
Fig. 1 is a schematic structural diagram of a PCB type current transformer with a calibration function according to the present invention;
FIG. 2 is a jth sub-signal acquisition circuit diagram in the PCB type current transformer with correction function according to the present invention;
FIG. 3 is a signal processing circuit diagram of a PCB type current transformer with a calibration function according to the present invention;
FIG. 4 shows a PCB type current transformer with a calibration function according to the present invention, which has an inner diameter r1Outer diameter of r2PCB type current sensing unit circuit boardSchematic representation.
Illustration of the drawings:
1. a PCB type current sensing unit; 2. a power supply circuit; 3. the signal acquisition circuit comprises M identical sub-signal acquisition circuits; 4. a signal processing circuit; 5. a temperature sensing circuit; 6. an analog-to-digital conversion circuit; 7. a microprocessor; 8. a communication interface; 9. a first sub-signal acquisition circuit; 10. a first tunnel magnetoresistance effect magnetic field sensor; 11. an Nth tunnel magnetoresistance effect magnetic field sensor; 12. a first resistor; 13. an Nth first resistor; 14. a first second resistor; 15. an Nth second resistor; 16. a third resistor; 17. a fourth resistor; 18. a first operational amplifier; 19. a fifth resistor; 20. a first capacitor; 21. a first sub-signal acquisition circuit; 22. the Mth sub-signal acquisition circuit; 23. a first sixth resistor; 24. m sixth resistors; 25. a second capacitor; 26. a seventh resistor; 27. a second operational amplifier; 28. an eighth resistor; 29. a ninth resistor; 30. a third capacitor; 31. a tenth resistor; 32. a third operational amplifier; 33. an eleventh resistor; 34. a twelfth resistor; 35. a fourth capacitor; 36. a PCB type current sensing unit circuit board; 37. a first tunnel magnetoresistance effect magnetic field sensor of a first sub-signal acquisition circuit diagram; 38. a first tunnel magnetoresistance effect magnetic field sensor of a second sub-signal acquisition circuit diagram; 39. a first tunnel magnetoresistance effect magnetic field sensor of the Mth sub-signal acquisition circuit diagram; 40. the first tunnel magnetoresistance effect magnetic field sensor of the third sub-signal acquisition circuit diagram; 41. a conductor carrying a current to be measured; 42. the PCB type current sensing unit comprises three input ends of a direct current positive voltage, a direct current negative voltage and a ground signal of a power circuit, an output end of a signal processing circuit and an output end of a temperature sensing circuit.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Referring to fig. 1-4, the present invention provides a technical solution: the PCB type current transformer with the correction function comprises a PCB type current sensing unit 1 and a signal data processing and transmission unit comprising an analog-to-digital conversion circuit 6, a microprocessor 7 and a communication interface 8, wherein the direct current rated current of the PCB type current transformer with the correction function is 600A, the rated frequency is 50Hz when alternating current is measured, the measurement range is +/-600A, the secondary rated output voltage is 0.5V, the direct current supply voltage of a power supply circuit is +/-12V, N is 5, and M is 3, the PCB type current sensing unit 1 comprises a power supply circuit 2, a signal acquisition circuit 3, a signal processing circuit 4 and a temperature sensing circuit 5, the signal acquisition circuit comprises M identical sub-signal acquisition circuits 9, and each sub-signal acquisition circuit 3 comprises N magneto-resistance effect magnetic field sensors with a Wheatstone full-bridge structure design, N first resistors, N second resistors, a resistor and a resistor, A third resistor 16, a fourth resistor 17, a fifth resistor 19, a first capacitor 20 and a first operational amplifier 18, wherein MxN tunnel magnetoresistance effect magnetic field sensors of M sub-signal acquisition circuits are uniformly distributed on the circumference of a PCB with the radius of the PCB, the other end of the corresponding first resistor is connected with the inverting input end of the first operational amplifier 18, the analog difference positive output end of each tunnel magnetoresistance effect magnetic field sensor is connected with one end of the corresponding second resistor, the tunnel magnetoresistance effect magnetic field sensors adopt TRM2102, eighteen tunnel magnetoresistance effect magnetic field sensors are uniformly distributed on the circumference with the radius of R being 45mm, a temperature sensing circuit adopts a temperature sensor chip BD1020HFV, the output signals of the temperature sensor chip tau are output after being processed by a follower and an amplifying circuit, and parameters are output by parameter sensor chip tau through parameter processing and parameter processing by a follower and an amplifying circuit1～τ4Are all 2 × 10-4Parameter τ5～τ8Are all 2 × 10-5The other end of the corresponding second resistor is connected to the non-inverting input terminal of the first operational amplifier 18, one end of the third resistor 16 is connected to the inverting input terminal of the first operational amplifier 18, the other end of the third resistor 16 is connected to the output terminal of the first operational amplifier 18, one end of the fourth resistor 17 is connected to the non-inverting input terminal of the first operational amplifier 18, and the fourth resistor 17 is connected to the non-inverting input terminal of the first operational amplifier 18The other end of the resistor 17 is grounded, one end of a fifth resistor 19 is connected with the output end of the first operational amplifier 18, the other end of the fifth resistor 19 is connected with one end of a first capacitor 20 and the output end of the sub-signal acquisition circuit, the other end of the first capacitor 20 is grounded, the signal processing circuit comprises M sixth resistors, a seventh resistor 26, an eighth resistor 28, a ninth resistor 29, a tenth resistor 31, an eleventh resistor 33, a twelfth resistor 34, a second capacitor 25, a third capacitor 30, a fourth capacitor 35, a second operational amplifier 27 and a third operational amplifier 32, and has M acquisition signal input ends and a signal output end, the M acquisition signal input ends are respectively connected with the output ends of the M sub-signal acquisition circuits one by one, each acquisition signal input end has a corresponding sixth resistor, each acquisition signal input end is connected with one end of a corresponding sixth resistor, the other end of the corresponding sixth resistor is connected with the inverting input end of the second operational amplifier 27, the non-inverting input end of the second operational amplifier 27 is grounded, the PCB type current sensing unit 1 is fixed in an annular shielding box which is grooved along the circumference in the middle of the inner annular surface, the signal data processing and transmitting unit comprising the analog-to-digital conversion circuit 6, the microprocessor 7 and the communication interface 8 is fixed in a square shielding box, the PCB type current sensing unit 1 and the annular shielding box are fixed in the body of the mutual inductor through epoxy resin vacuum casting, and the three input ends of the direct current positive voltage, the direct current negative voltage and the ground signal of the power circuit 2 are connected with the aviation socket fixed on the body.
The principle of the present solution is further explained as follows:
MxN tunnel magneto-resistance effect magnetic field sensors on the PCB ring are uniformly distributed on the circumference with the radius of r, and a conductor carrying the current to be measured passes through the circle center of the PCB ring and is vertical to the plane of the PCB ring. The kth tunnel magnetoresistance effect magnetic field sensor considering the jth sub-signal acquisition circuit outputs a voltage signal delta u in a differential modejkComprises the following steps:
in which I is the measured current, KjkIs the conversion coefficient of the magnetic field sensor, rjkIs the actual distance of the magnetic field sensor from the conductor. Thus, the input I(s) and output u of the current sensing system consisting of M identical signal acquisition circuits and one signal processing circuitctThe relationship of(s) is:
wherein
And τ1＝R5C1、τ2＝R7C2、τ3＝R10C3、
Due to the discreteness and temperature drift of the resistance value and the characteristics of the tunnel magnetoresistance effect magnetic field sensor, and the installation error of the tunnel magnetoresistance effect magnetic field sensor and the conductor, Kjk、rjkThe sum K is different from an ideal value, so that the accuracy is reduced, and the frequency response characteristic of the system is influenced by several resistance-capacitance links. The microprocessor corrects equation (2) by a temperature correction algorithm, an error correction algorithm, and a correction algorithm based on a series correction transfer function. The series correction transfer function for the frequency response characteristic correction algorithm is as follows:
the equation (5) can be processed into a Z-domain transfer function by using a bilinear transformation method, and the frequency response characteristic of the system is represented byτ5～τ8And (6) determining. Coefficient in the formula (2)
The calibration can be carried out under the conditions of a plurality of known measured currents and a certain determined temperature, and the error correction algorithm corrects the amplitude error and the nonlinear error of the coefficient according to the obtained error value. Meanwhile, the temperature drift error of the output signal of the signal processing circuit is corrected according to the temperature analog quantity output by the temperature sensing circuit and the related temperature coefficient given by the magnetic field sensor manual of the tunnel magnetoresistance effect, and the parameter tau1～τ4Are not more than 2 x 10-4Parameter τ5～τ8Are not more than 2 x 10-5。
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention should be equivalent or changed within the scope of the present invention.
Claims (6)
1. The utility model provides a PCB type current transformer of area correction function, include PCB type current sensing unit (1) and the signal data processing and the transmission element who contains analog-to-digital conversion circuit (1), microprocessor (7) and communication interface (8), a serial communication port, PCB type current sensing unit (1) includes power supply circuit (2), signal acquisition circuit (3), signal processing circuit (4) and temperature sensing circuit (4), signal acquisition circuit contains M the same sub-signal acquisition circuit (9), every sub-signal acquisition circuit (3) all contain N tunnel magneto resistance effect magnetic field sensor, N first resistance, N second resistance, third resistance (16), fourth resistance (17), fifth resistance (19), first electric capacity (20) and first operational amplifier (18) that have Wheatstone full-bridge structural design, M tunnel magneto resistance effect magnetic field sensor of sub-signal acquisition circuit's MxN distributes uniformly in that PCB's radius does Circumferentially, the other end of the corresponding first resistor is connected with the inverting input end of the first operational amplifier (18), the analog differential positive output end of each tunneling magneto-resistance effect magnetic field sensor is connected with one end of the corresponding second resistor, the other end of the corresponding second resistor is connected with the non-inverting input end of the first operational amplifier (18), one end of the third resistor (16) is connected with the inverting input end of the first operational amplifier (18), the other end of the third resistor (16) is connected with the output end of the first operational amplifier (18), one end of the fourth resistor (17) is connected with the non-inverting input end of the first operational amplifier (18), the other end of the fourth resistor (17) is grounded, one end of the fifth resistor (19) is connected with the output end of the first operational amplifier (18), and the other end of the fifth resistor (19) is connected with one end of the first capacitor (20) and the output end of the sub-signal acquisition circuit, the other end of the first capacitor (20) is grounded, the signal processing circuit comprises M sixth resistors, M seventh resistors (26), M eighth resistors (28), M ninth resistors (29), M tenth resistors (31), M eleventh resistors (33), M twelfth resistors (34), a second capacitor (25), a third capacitor (30), a fourth capacitor (35), a second operational amplifier (27) and a third operational amplifier (32), and has M acquisition signal input ends and a signal output end, wherein the M acquisition signal input ends are respectively connected with the output ends of the M sub-signal acquisition circuits one by one, each acquisition signal input end is provided with a corresponding sixth resistor, each acquisition signal input end is connected with one end of the corresponding sixth resistor, the other end of the corresponding sixth resistor is connected with the inverting input end of the second operational amplifier (27), and the non-inverting input end of the second operational amplifier (27) is grounded;
the second capacitor (25) and the seventh resistor (26) are connected in parallel with the inverting input end and the output end of the second operational amplifier (27), one end of the eighth resistor (28) and one end of the ninth resistor (29) are connected with the output end of the second operational amplifier (27), the other end of the eighth resistor (28) is grounded, the other end of the ninth resistor (29) is connected with the inverting input end and the output end of the third operational amplifier (32), the third capacitor (30) and the tenth resistor (31) are connected in parallel with the inverting input end and the output end of the third operational amplifier (32), one end of the eleventh resistor (33) is connected with the output end of the third operational amplifier (32), the other end of the eleventh resistor (33) is connected with one end of a fourth capacitor (35), one end of a twelfth resistor (34) and a signal output end of the signal processing circuit, and the other end of the fourth capacitor (35) and the other end of the twelfth resistor (34) are grounded.
2. The PCB type current transformer with the correction function according to claim 1, characterized in that the power circuit (2) has three input terminals of DC positive voltage, DC negative voltage and ground signal, the DC positive voltage of the power circuit (2) is 12V, and the DC negative voltage is-12V.
3. The PCB type current transformer with the correction function of claim 1, wherein the nonlinearity of the tunneling magneto-resistance effect magnetic field sensor is less than 1%.
4. The PCB type current transformer with the correction function of claim 1, wherein the communication interface adopts RS 232.
5. The PCB type current transformer with the correction function according to claim 1, wherein the temperature sensing circuit (5) is composed of a temperature sensing chip and a signal processing circuit thereof, the temperature sensing chip and the signal processing circuit are provided with a temperature analog output end, and the signal output end of the signal processing circuit (4) and the temperature analog output end of the temperature sensing circuit (5) output two paths of analog signals.
6. The PCB type current transformer with the correcting function according to claim 1, wherein the magnetic field detection sensitive direction of the tunnel magnetoresistance effect magnetic field sensors is a tangential direction of the circumferential position, each tunnel magnetoresistance effect magnetic field sensor has a corresponding first resistor and a corresponding second resistor, and the analog differential negative output end of each tunnel magnetoresistance effect magnetic field sensor is connected with one end of the corresponding first resistor.
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| CN117289018A (en) * | 2023-11-27 | 2023-12-26 | 成都赛迪育宏检测技术有限公司 | Fast and accurate FA-level current testing circuit |
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| CN104377011A (en) * | 2014-11-20 | 2015-02-25 | 国家电网公司 | Half-open type electronic current transformer |
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Address after: No. 8, Jingtian Road, Jiangshan Economic Development Zone, Jiangshan City, Quzhou City, Zhejiang Province 324102 Patentee after: Zhejiang Tianji Instrument Transformer Co.,Ltd. Address before: No.2 Shanhai Road, Shanhai cooperation zone, Jiangshan Economic Development Zone, Jiangshan City, Quzhou City, Zhejiang Province Patentee before: ZHEJIANG HORIZON INSTRUMENT TRANSFORMERS Co.,Ltd. |
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