CN107462758B - Closed loop current sensor - Google Patents
Closed loop current sensor Download PDFInfo
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- CN107462758B CN107462758B CN201710778921.4A CN201710778921A CN107462758B CN 107462758 B CN107462758 B CN 107462758B CN 201710778921 A CN201710778921 A CN 201710778921A CN 107462758 B CN107462758 B CN 107462758B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R15/00—Details of measuring arrangements of the types provided for in groups G01R17/00 - G01R29/00, G01R33/00 - G01R33/26 or G01R35/00
- G01R15/14—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks
- G01R15/20—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using galvano-magnetic devices, e.g. Hall-effect devices, i.e. measuring a magnetic field via the interaction between a current and a magnetic field, e.g. magneto resistive or Hall effect devices
- G01R15/205—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using galvano-magnetic devices, e.g. Hall-effect devices, i.e. measuring a magnetic field via the interaction between a current and a magnetic field, e.g. magneto resistive or Hall effect devices using magneto-resistance devices, e.g. field plates
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R15/00—Details of measuring arrangements of the types provided for in groups G01R17/00 - G01R29/00, G01R33/00 - G01R33/26 or G01R35/00
- G01R15/14—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks
- G01R15/20—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using galvano-magnetic devices, e.g. Hall-effect devices, i.e. measuring a magnetic field via the interaction between a current and a magnetic field, e.g. magneto resistive or Hall effect devices
- G01R15/207—Constructional details independent of the type of device used
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/0092—Arrangements for measuring currents or voltages or for indicating presence or sign thereof measuring current only
Abstract
The application discloses a closed loop current sensor, comprising: at least one compensation coil disposed at a predetermined position of a wire through which a current to be measured flows; at least one magnetic sensing chip, each magnetic sensing chip is arranged in the cavity tube of one compensation coil and is used for measuring the intensity of the magnetic field of the current to be measured and the superimposed magnetic field of the compensation magnetic field; the control module is used for outputting current with a preset size according to the output signal of the magnetic sensing chip; the input end of the control module is connected with the output end of the magnetic sensing chip, and the output end of the control module is connected with one end of the compensation coil; and the input end of the IV conversion module is connected with the other end of the compensation coil, and the output end of the IV conversion module is used as the output end of the closed-loop current sensor. Because the magnetic field intensity in the cavity tube of the compensation coil is relatively uniform, the magnetic sensing chip of the closed loop current sensor can relatively accurately measure the intensity of the superimposed magnetic field under the condition of no magnetic core. The closed loop current sensor without the magnetic core has the advantages of relatively small volume, light weight and low manufacturing cost.
Description
Technical Field
The application relates to the technical field of current sensors, in particular to a closed-loop current sensor.
Background
The current sensor is widely applied to the fields of new energy, intelligent transportation, industrial control, intelligent household appliances, intelligent power grids and the like. Commonly used current sensors fall into two broad categories, open loop and closed loop. The open loop type current sensor is characterized in that a magnetic core with an air gap is arranged around a tested wire, a magnetic sensing unit is positioned in the air gap, the magnetic core generates induced potential due to the law of electromagnetic induction, the magnetic sensing unit can measure the magnetic field at the air gap of the magnetic core, and the rear end can calculate the magnitude of the tested current according to the output signal of the magnetic sensing unit. The open loop type current sensing works in a way of directly measuring a magnetic field, so that hysteresis and saturation of a magnetic core can occur under the action of high current, and the measurement accuracy is affected.
To overcome the above problems, one skilled in the art measures current using a closed loop current sensor. Unlike the open loop current sensor, the magnetic core of the closed loop current sensor is wound with a compensation coil, the compensation coil is electrically connected with the magnetic sensing unit, the compensation coil is powered by the output voltage of the magnetic sensing unit and is used for compensating the magnetic field generated by the measured current, and when the magnetic balance is achieved, the magnetic field generated by the compensation current is approximately the same as the magnetic field generated by the measured current, so that the magnetic core usually works in an environment without magnetic flux or with small magnetic flux, and hysteresis and saturation phenomena can be overcome. The back end can calculate the measured current by directly measuring the current of the compensation coil.
As shown in fig. 1, chinese patent document (CN 203259575U) discloses a closed loop current sensor, which includes a magnetic focusing ring provided with an opening, a wire through which a current to be measured flows and a compensation coil are wound on the magnetic focusing ring, respectively, a magnetic field in the magnetic focusing ring is detected by a hall element disposed at the opening of the magnetic focusing ring, and when the magnetic field is detected, the compensation current is controlled to flow through the compensation coil, so that a magnetic field opposite to the current to be measured is generated in the magnetic focusing ring.
However, on one hand, the magnetic flux collecting ring in the closed-loop current sensor is often larger in size, so that the closed-loop current sensor is larger in volume and heavier in weight; on the other hand, the price of the magnetic flux collecting ring as the magnetic core tends to be high, so that the manufacturing cost of the closed-loop current sensor is high.
Disclosure of Invention
Therefore, the embodiment of the application provides a closed-loop current sensor, which solves the problems of larger volume, heavier weight and higher manufacturing cost of the traditional closed-loop current sensor.
The embodiment of the application provides a closed loop current sensor, which comprises: at least one compensation coil arranged at a predetermined position of a wire through which a current to be measured flows for generating a compensation magnetic field opposite to a magnetic field of the current to be measured; at least one magnetic sensing chip, each magnetic sensing chip is arranged in a cavity tube of one compensation coil and is used for measuring the intensity of the magnetic field of the current to be measured and the superimposed magnetic field of the compensation magnetic field; the control module is used for outputting current with a preset size according to the output signal of the magnetic sensing chip; the input end of the control module is connected with the output end of the magnetic sensing chip, and the output end of the control module is connected with one end of the compensation coil; the input end of the IV conversion module is connected with the other end of the compensation coil, and the output end of the IV conversion module is used as the output end of the closed-loop current sensor; the IV conversion module converts a current signal of the compensation coil into a voltage signal.
Optionally, the at least one compensation coil comprises at least two compensation coils, and a magnetic sensing chip is arranged in a cavity tube of each compensation coil.
Optionally, the magnetic sensing chips in the inner cavities of the at least two compensation coils are symmetrically arranged relative to the wires through which the current to be measured flows.
Optionally, the control module includes a VI conversion unit; the VI conversion unit includes: and the two input ends of the first operational amplification unit are respectively connected with the output ends of the two magnetic sensing chips, and the output ends of the first operational amplification unit are connected with the compensation coils.
Optionally, the two compensation coils are connected in series, one end after the series connection is connected with the output end of the control module, and the other end after the series connection is connected with the input end of the IV conversion module.
Optionally, the IV conversion module includes: and the first input end of the second operational amplifier is connected with the other end of the compensation coil, the second input end of the second operational amplifier is connected with a reference voltage, and a resistor is connected between the first input end and the output end.
Optionally, the magnetic sensing chip includes: the first serial branch comprises a first magnetic resistor and a second magnetic resistor which are connected in series; the second serial branch comprises a third magnetic resistor and a fourth magnetic resistor which are connected in series; the first serial branch circuit and the second serial branch circuit are arranged in parallel, and two ends after being connected in parallel are connected with a power supply; the magnetic sensing chip further includes: a third operational amplification unit having a first input terminal connected between the first magnetic resistor and the second magnetic resistor and a second input terminal connected between the third magnetic resistor and the fourth magnetic resistor; the third operational amplification unit amplifies the difference value of the signals of the two input ends.
Optionally, one end of the first magnetic resistor is connected with one end of the third magnetic resistor, and one end of the second magnetic resistor is connected with one end of the fourth magnetic resistor; the initial resistance values and the magnetic sensitivities of the first magnetic resistor, the second magnetic resistor, the third magnetic resistor and the fourth magnetic resistor are all equal; and the magnetic sensitivity direction of the first magnetic resistor is the same as that of the fourth magnetic resistor, and the magnetic sensitivity direction of the second magnetic resistor is the same as that of the third magnetic resistor.
Optionally, the closed loop current sensor further comprises a printed circuit board, and the control module and/or the IV conversion module are/is arranged on the printed circuit board.
Optionally, the compensation coil is vertically fixed on the plane of the printed circuit board through a bracket.
According to the closed-loop current sensor provided by the embodiment of the application, the compensation coil is arranged at the preset position of the lead through which the current to be measured flows, the magnetic sensing chip is arranged in the cavity tube of the compensation coil, and the control module outputs the current with the preset size according to the output signal of the magnetic sensing chip to control the compensation coil to generate the compensation magnetic field opposite to the magnetic field of the current to be measured, so that the superposition magnetic field measured by the magnetic sensing chip is reduced, and a closed-loop structure is formed. Because the magnetic field intensity in the cavity tube of the compensation coil is relatively uniform, the magnetic sensing chip of the closed loop current sensor can relatively accurately measure the intensity of the superimposed magnetic field under the condition of lacking a magnetic core. The closed loop current sensor without the magnetic core has the advantages of relatively small volume, light weight and low manufacturing cost.
Drawings
The features and advantages of the present application will be more clearly understood by reference to the accompanying drawings, which are illustrative and should not be construed as limiting the application in any way, in which:
FIG. 1 shows a schematic diagram of a prior art closed loop current sensor;
FIG. 2 shows a schematic diagram of a closed loop current sensor according to an embodiment of the application;
FIG. 3 is a schematic top view of a predetermined location of a wire through which a current to be measured flows;
fig. 4 shows a front view of a predetermined position of a wire through which a current to be measured flows;
FIG. 5 shows a schematic diagram of another closed loop current sensor according to an embodiment of the application;
FIG. 6 shows a schematic diagram of the connections of a controller according to an embodiment of the application;
FIG. 7 shows a schematic diagram of a magnetic sensor chip;
FIG. 8 shows a schematic diagram of another magnetic sensor chip;
FIG. 9 illustrates a front view of the complete structure of a closed loop current sensor of an embodiment of the present application;
fig. 10 shows a top view of a complete structure of a closed loop current sensor according to an embodiment of the application.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present application more apparent, the technical solutions of the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application, and it is apparent that the described embodiments are some embodiments of the present application, but not all embodiments of the present application. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to fall within the scope of the application.
Example 1
Fig. 2 shows a schematic diagram of a closed loop current sensor according to an embodiment of the application. As shown in fig. 2, the closed loop current sensor includes at least one compensation coil 10, at least one magnetic sensing chip 20, a control module 30, and an IV conversion module 40. The left "x" in fig. 2 indicates that the wire through which the current to be measured flows is perpendicular to the paper surface, and the current flow is in the direction penetrating into the paper surface.
The compensation coil 10 is disposed at a predetermined position of a wire through which a current to be measured flows, for generating a compensation magnetic field opposite to a magnetic field of the current to be measured. The "predetermined position" refers to the distance and orientation of the wire through which the current to be measured flows, and several predetermined positions are shown in fig. 3 and 4. The dots in fig. 3 indicate that the wire through which the current to be measured flows is perpendicular to the paper surface, and the current flows in a direction out of the paper surface, and the dotted lines in fig. 3 and 4 indicate the magnetic field of the current to be measured. The compensation coils may be disposed at any one or more of the locations shown as diamond, pentagon, or five-pointed in fig. 3 and 4.
Each of the magnetic sensor chips 20 is disposed in a lumen of one of the compensation coils 10 for measuring the strength of a magnetic field of a current to be measured and a superimposed magnetic field of the compensation magnetic field. As shown in fig. 2, one or more magnetic sensor chips 20 may be disposed in one compensation coil.
The control module 30 is used for outputting a current with a predetermined magnitude according to the output signal of the magnetic sensor chip 20. The input end of the control module 30 is connected with the output end of the magnetic sensing chip 20, and the output end of the control module 30 is connected with one end of the compensation coil 10.
The input end of the IV conversion module 40 is connected to the other end of the compensation coil 10, and the output end of the IV conversion module 40 serves as the output end of the closed loop current sensor. The IV conversion module converts the current signal of the compensation coil 10 into a voltage signal.
When the positions of the compensation coils are more than one, the compensation coils can be respectively connected with the control module; or the compensation coils can be connected in series and then connected with the control module after being connected in series.
The control module 30 may include a microprocessor, a power supply and a controllable switch, where the microprocessor receives and processes the output signal of the magnetic sensor chip 20, and then outputs a control signal to control the controllable switch to adjust the current value in the compensation coil 10; alternatively, the control module 30 may be a VI conversion unit, which converts the output voltage of the magnetic sensor 20 into a current signal and inputs the current signal to the compensation coil.
According to the closed loop current sensor, the compensation coil is arranged at the preset position of the lead through which the current to be measured flows, the magnetic sensing chip is arranged in the cavity tube of the compensation coil, the control module outputs the current with the preset size according to the output signal of the magnetic sensing chip to control the compensation coil to generate the compensation magnetic field opposite to the magnetic field of the current to be measured, and the closed loop structure can enable the superimposed magnetic field to be kept to be zero. Because the intensity of the compensating magnetic field in the cavity tube of the compensating coil is relatively uniform, the magnetic sensing chip of the closed loop current sensor can relatively accurately measure the intensity of the superimposed magnetic field under the condition of lacking a magnetic core. The closed loop current sensor without the magnetic core has the advantages of relatively small volume, light weight and low manufacturing cost.
Example two
Fig. 5 shows a schematic diagram of another closed loop current sensor according to an embodiment of the application. As shown in fig. 5, the closed loop current sensor is different from the first embodiment in that it includes at least two compensation coils 11 and 12, two magnetic sensing chips 21 and 22, a control module 30, and an IV conversion module 40.
The magnetic sensor chip 21 is disposed in the cavity of the compensation coil 11, and the magnetic sensor chip 22 is disposed in the cavity of the compensation coil 12. The wire through which the current to be measured flows is arranged between the two compensation coils 21 and 22.
The "X" in FIG. 5 shows that the wire through which the current to be measured flows is perpendicular to the paper surface, and the current flows in the direction penetrating into the paper surface, B I1 And B I2 A magnetic field representing the current to be measured, B C1 And B C2 Representing the magnetic field of the compensation coil. Since the directions of the magnetic fields of the wires through which the current to be measured flows are opposite at the positions of the compensation coils 11 and 12 in fig. 5, the winding directions and the connection modes of the compensation coils 11 and 12 need to ensure that the directions of the magnetic fields generated by the compensation coils 11 and 12 are opposite when the current is applied so as to cancel the magnetic fields of the current to be measured. Note that, the winding method and the connection method of the compensation coil in the present application are not limited to those shown in fig. 5.
Further, the control module 30 includes a VI conversion unit. As shown in fig. 6, the VI conversion unit may be a first operational amplification unit 31, and two input ends of the first operational amplification unit 31 are respectively connected to output ends of the two magnetic sensing chips 21 and 22, and the output ends are connected to the compensation coil. The VI conversion unit converts the voltage signals output from the two magnetic sensing chips 21 and 22 into current signals, and inputs the current signals into the compensation coil.
Further, the magnetic sensing chip 21 in the inner cavity of the compensation coil 11 and the magnetic sensing chip 22 in the compensation coil 12 are symmetrically arranged relative to the wires through which the current to be measured flows. In the embodiment of the application, the symmetrically arranged magnetic sensing chips have the effect of common mode inhibition, and the principle is as follows; since the directions of the magnetic fields of the wires through which the currents to be measured flow at the positions where the magnetic sensors 21 and 22 are located are opposite, the directions of the superimposed magnetic fields of the currents to be measured and the compensation magnetic fields should be opposite if the superimposed magnetic fields are not zero. In the dynamic change process at the time of measurement, the difference between the signals outputted from the magnetic sensor chips 21 and 22 is a-B assuming that the signals are a and B, respectively, at a certain time. When electromagnetic interference exists in the actual measurement environment, the directions of the interfering magnetic fields at the positions of the magnetic sensor chips 21 and 22 are generally the same, that is, the electromagnetic interference is a common-mode interference signal. Since the magnetic sensor chips 21 and 22 are symmetrical in position and identical in structure, the common-mode interference signal makes the variation of the output values of the magnetic sensor chips 21 and 22 identical, and the output signals of the magnetic sensor chips 21 and 22 are A+C and B+C, respectively, assuming that the variation is C, and the difference between the two is still A-B. It can be seen that the common-mode interference signal does not affect the output result of the first operational amplification unit 31, i.e. the closed-loop current sensor has the function of common-mode rejection.
As an alternative implementation of this embodiment, the two compensation coils 11 and 12 are connected in series, and one end after the series connection is connected to the output end of the control module 30.
The input end of the IV conversion chip 40 is connected to the other end of the compensation coils 11 and 12 after being connected in series, and the output end of the IV conversion chip 40 serves as the output end of the closed loop current sensor. The IV conversion module converts the current signal of the compensation coil into a voltage signal.
Alternatively, as shown in fig. 6, the IV conversion module 40 includes a second operational amplifier, a first input terminal of the second operational amplifier is connected to the other end after the compensation coils 11 and 12 are connected in series, a second input terminal of the second operational amplifier is connected to the reference voltage, and a resistor is connected between the first input terminal and the output terminal of the second operational amplifier.
As an alternative implementation of the present embodiment, the magnetic sensor chip 20 includes a first series branch and a second series branch. The first serial branch circuit comprises a first magnetic resistor and a second magnetic resistor which are connected in series; the second series branch includes a third and a fourth magneto resistor connected in series. The first serial branch circuit and the second serial branch circuit are arranged in parallel, and two ends of the parallel connection are connected with a power supply. In addition, the magnetic sensing chip 20 further includes a third operational amplification unit, a first input terminal of which is connected between the first magnetic resistor and the second magnetic resistor, and a second input terminal of which is connected between the third magnetic resistor and the fourth magnetic resistor; the third operational amplification unit amplifies the difference value of the two input end signals.
As shown in fig. 7, the magnetic sensor chip 21 includes a first magnetoresistive resistor R connected in series 11 And a second magnetoresistance R 12 Third magnetoresistive resistor R connected in series 13 And a fourth magnetoresistance R 14 The two serially connected branches are connected in parallel, and the two ends of the serially connected branches are connected with a power supply. The magnetic sensor chip 21 further comprises a third operational amplifier 15 with a first input connected to the first magnetic resistor R 11 And a second magnetoresistance R 12 A second input end is connected with the third magnetic resistor R 13 And a fourth magnetoresistance R 14 Between them. The structure of the magnetic sensor chip 22 is similar to that of the magnetic sensor chip 21, as shown in fig. 8, and will not be described again here.
Among the four magnetic resistors in the magnetic sensing chip, two magnetic resistors which are diagonally arranged are common resistors, and the other two magnetic resistors are magnetic resistors with initial values and/or equal magnetic sensitivities. When the superimposed magnetic field of the current to be measured and the magnetic field of the compensation coil is zero, the signal value output by the serial-parallel structure of the magnetic resistor is 0, or a constant value (under the condition of common mode interference); when the superimposed magnetic field increases by one unit, the signal value output by the serial-parallel structure of the magnetic resistors increases by more than one unit, so that the magnetic sensing chip adopts the serial-parallel structure of the magnetic resistors to improve the measurement accuracy and the sensitivity of the magnetic sensing chip.
Further, one end of the first magnetic resistor is connected with one end of the third magnetic resistor, and one end of the second magnetic resistor is connected with one end of the fourth magnetic resistor. The initial resistance and the magnetic sensitivity of the first magnetic resistor, the second magnetic resistor, the third magnetic resistor and the fourth magnetic resistor are all equal, the magnetic sensitivity direction of the first magnetic resistor is the same as that of the fourth magnetic resistor, and the magnetic sensitivity direction of the second magnetic resistor is the same as that of the third magnetic resistor. The design can further improve the measurement accuracy and the sensitivity of the magnetic sensing chip on the basis of the magnetic resistance serial-parallel structure.
The phrase "the same magnetic sensitivity direction" herein means that the resistance values of the magneto-resistors are increased or decreased under the magnetic field in the same direction; "opposite magnetically sensitive directions" means that the resistance value of one of the magnetoresistors increases and the resistance value of the other magnetoresistor decreases under a magnetic field in the same direction. The "magnetosensitive property" herein means the amount of change in the resistance value of the magnetoresistive element when the magnetic field in which it is positioned is changed by one unit.
As shown in fig. 7, in the magnetic sensor chip 21, a first magnetoresistance R 11 Second magnetic resistor R 12 Third magnetic resistor R 13 And a fourth magnetoresistance R 14 The initial resistance and the magnetic sensitivity of the magnetic resistance are equal, and the first magnetic resistance R 11 And a fourth magnetoresistance R 14 The magnetic sensitivity direction of (2) is the same, the second magnetic resistance R 12 And a third magnetic resistance R 13 The magnetic sensitivity direction of (2) is the same. The magnetic sensor chip 22 is similar to the magnetic sensor chip 21, and will not be described here again.
Fig. 9 and 10 show a front view and a top view, respectively, of the complete structure of a closed loop current sensor according to an embodiment of the present application, wherein 50 is a printed circuit board on which the control module 30 and/or the IV conversion module 40 are disposed. The compensation coil is wound on a bracket which is vertically fixed on the printed circuit board. The coil is wound on the outside of the bracket, so that the heat dissipation is good.
Further, 61 and 62 represent schematic views of the housing of the closed loop current sensor, the housing being annular, 61 representing the inner annular wall, and 62 representing the outer annular wall. During measurement, a lead through which a current to be measured flows passes through the inner annular ring.
Reference numeral 70 denotes a lead pin provided on the printed circuit board 50, and the pin 70 is exposed through a through hole in the housing so as to lead out a measurement signal of the closed loop current sensor.
It will be appreciated by those skilled in the art that implementing all or part of the above-described embodiment method may be implemented by a computer program to instruct related hardware, where the program may be stored in a computer readable storage medium, and the program may include the above-described embodiment method when executed. The storage medium may be a magnetic disk, an optical disk, a read-only memory (ROM), a random-access memory (RAM), or the like.
Although embodiments of the present application have been described in connection with the accompanying drawings, various modifications and variations may be made by those skilled in the art without departing from the spirit and scope of the application, and such modifications and variations are within the scope of the application as defined by the appended claims.
Claims (10)
1. A closed loop current sensor, comprising:
at least one compensation coil arranged at a predetermined position of a wire through which a current to be measured flows for generating a compensation magnetic field opposite to a magnetic field of the current to be measured;
at least one magnetic sensing chip, each magnetic sensing chip is arranged in a cavity tube of one compensation coil and is used for measuring the intensity of the magnetic field of the current to be measured and the superimposed magnetic field of the compensation magnetic field;
the control module is used for outputting current with a preset size according to the output signal of the magnetic sensing chip; the input end of the control module is connected with the output end of the magnetic sensing chip, and the output end of the control module is connected with one end of the compensation coil;
the input end of the IV conversion module is connected with the other end of the compensation coil, and the output end of the IV conversion module is used as the output end of the closed-loop current sensor; the IV conversion module converts a current signal of the compensation coil into a voltage signal.
2. The closed loop current sensor of claim 1, wherein the at least one compensation coil comprises at least two compensation coils, each compensation coil having a magnetic sense die disposed within a lumen of the compensation coil.
3. The closed loop current sensor of claim 1, wherein the magnetic sensing chips in the at least two compensation coil lumens are symmetrically disposed with respect to the wire through which the current to be measured flows.
4. The closed loop current sensor of claim 2, wherein the control module comprises a VI conversion unit; the VI conversion unit includes:
and the two input ends of the first operational amplification unit are respectively connected with the output ends of the two magnetic sensing chips, and the output ends of the first operational amplification unit are connected with the compensation coils.
5. The closed loop current sensor of claim 4, wherein the two compensation coils are connected in series, one end of the two compensation coils being connected to the output of the control module, and the other end of the two compensation coils being connected to the input of the IV conversion module.
6. The closed loop current sensor of claim 5, wherein the IV conversion module comprises:
and the first input end of the second operational amplifier is connected with the other end of the compensation coil, the second input end of the second operational amplifier is connected with a reference voltage, and a resistor is connected between the first input end and the output end.
7. The closed loop current sensor of claim 1, wherein the magnetic sensing chip comprises:
the first serial branch comprises a first magnetic resistor and a second magnetic resistor which are connected in series;
the second serial branch comprises a third magnetic resistor and a fourth magnetic resistor which are connected in series;
the first serial branch circuit and the second serial branch circuit are arranged in parallel, and two ends after being connected in parallel are connected with a power supply;
the magnetic sensing chip further includes:
a third operational amplification unit having a first input terminal connected between the first magnetic resistor and the second magnetic resistor and a second input terminal connected between the third magnetic resistor and the fourth magnetic resistor; the third operational amplification unit amplifies the difference value of the signals of the two input ends.
8. The closed loop current sensor of claim 7, wherein one end of the first magnetic resistor is connected to one end of the third magnetic resistor, and one end of the second magnetic resistor is connected to one end of the fourth magnetic resistor;
the initial resistance values and the magnetic sensitivities of the first magnetic resistor, the second magnetic resistor, the third magnetic resistor and the fourth magnetic resistor are all equal; and, in addition, the processing unit,
the magnetic sensitivity directions of the first magnetic resistor and the fourth magnetic resistor are the same, and the magnetic sensitivity directions of the second magnetic resistor and the third magnetic resistor are the same.
9. The closed loop current sensor of claim 1, further comprising a printed circuit board, the control module and/or the IV conversion module being disposed on the printed circuit board.
10. The closed loop current sensor of claim 9 wherein the compensation coil is vertically fixed to the printed circuit board plane by a bracket.
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| CN201710778921.4A CN107462758B (en) | 2017-08-31 | 2017-08-31 | Closed loop current sensor |
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| CN201710778921.4A CN107462758B (en) | 2017-08-31 | 2017-08-31 | Closed loop current sensor |
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| CN111505363A (en) * | 2020-04-13 | 2020-08-07 | 深圳市知用电子有限公司 | Closed-loop current transformer |
| CN111505338B (en) * | 2020-05-03 | 2021-07-02 | 华中科技大学 | Magnetic feedback closed-loop acceleration sensor and temperature compensation method thereof |
| CN112147393B (en) * | 2020-09-07 | 2021-07-13 | 珠海多创科技有限公司 | Design method of closed-loop current sensor |
| CN112083211A (en) * | 2020-09-17 | 2020-12-15 | 上海矽睿科技有限公司 | Current sensor |
| CN112362941B (en) * | 2020-12-04 | 2023-06-30 | 中国电力科学研究院有限公司 | Annular current transformer and current measuring method thereof |
| CN113820532B (en) * | 2021-09-23 | 2022-04-15 | 南方电网数字电网研究院有限公司 | Non-contact double-core cable current measuring method and device |
| CN116539942A (en) * | 2023-07-06 | 2023-08-04 | 深圳市知用电子有限公司 | Magnetic flux detection system and current sensor |
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