CN117405958B - current sensor - Google Patents
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- CN117405958B CN117405958B CN202311714802.4A CN202311714802A CN117405958B CN 117405958 B CN117405958 B CN 117405958B CN 202311714802 A CN202311714802 A CN 202311714802A CN 117405958 B CN117405958 B CN 117405958B
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- 230000002452 interceptive effect Effects 0.000 claims description 2
- 238000005259 measurement Methods 0.000 abstract description 11
- 238000001514 detection method Methods 0.000 abstract description 3
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Classifications
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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
- 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 disclosure provides a current sensor, relates to the technical field of current detection. The current sensor includes a magnetosensitive unit and a current conductor. The current conductor comprises three parallel segments which are sequentially and equidistantly arranged in the same plane; the measured currents flow in opposite directions and are equal in magnitude in adjacent parallel segments. The relative positions of the first magnetic resistor and the first parallel segment, the second magnetic resistor and the second parallel segment and the third magnetic resistor and the third parallel segment are the same. The first magnetic resistor and one of the second magnetic resistors counteract the output of the external interference magnetic field, and the third magnetic resistor and the other of the second magnetic resistors counteract the output of the external interference magnetic field; the first magnetic resistor and the second magnetic resistor have opposite sensitivity directions, and the second magnetic resistor and the third magnetic resistor have opposite sensitivity directions. The magneto-sensitive unit has the advantage of external field interference resistance, can effectively eliminate the influence of an interference magnetic field/an environment magnetic field, and improves the measurement accuracy of the current.
Description
Technical Field
The invention relates to the technical field of current detection, in particular to a current sensor.
Background
The current sensor is used for measuring the current in the current transmission medium, and can be widely applied to various scenes requiring current measurement, for example, a Battery Management System (BMS) needs to integrate a large number of current sensors to measure the current during charge and discharge of a relevant battery Pack, and a frequency converter needs to integrate a large number of current sensors to measure the current.
Fig. 1 is a main flow structure of a chip type current sensor in the prior art, and the main flow structure is a wheatstone full bridge circuit formed by four magneto resistors R1, R2, R3 and R4. The sensitive directions of the magnetic resistors R1 and R4 are the first direction perpendicular to the current plane, the sensitive directions of the magnetic resistors R2 and R3 are the second direction perpendicular to the current plane, and the first direction is opposite to the second direction. The existing chip type current sensor is easy to be interfered by an external magnetic field (such as an interference magnetic field, an environment magnetic field and the like), and when the external magnetic field has a component perpendicular to a current plane, the external magnetic field is overlapped with a magnetic field generated by a measured current, so that the current measurement is inaccurate. Namely, the existing chip type current sensor is easy to be interfered by external magnetic field signals, and the measurement accuracy is affected.
There are also some anti-interference current sensors, such as fig. 2, which discloses a current measuring device in the prior art, so as to eliminate interference of an interference magnetic field on current measurement. The specific method comprises the following steps: the tested current generates magnetic fields at more than three different positions, each position is provided with two magnetic resistors which correspond to the magnetic field directions and are opposite in direction, and the external interference field is resisted by the mode of serial-parallel connection of the two magnetic resistors. Although the interference field can be eliminated in the mode, more magnetic resistors are required to be arranged, the structure is complex, the size of the sensor is increased, and the final output signal is reduced. That is, the sensitivity of the current sensor itself is reduced at the expense of the sensitivity of the sensor while canceling the external field disturbance, which reduces the accuracy of the current magnitude measurement.
Disclosure of Invention
The invention aims to provide a current sensor, which can effectively eliminate the influence of an interference magnetic field/an environment magnetic field and improve the measurement accuracy of the current without reducing the sensitivity of the sensor.
Embodiments of the invention may be implemented as follows:
the current sensor provided by the embodiment adopts the magnetosensitive unit with the effect of eliminating the interference magnetic field to measure the current, and comprises a current conductor and the magnetosensitive unit. Wherein:
the current conductor comprises a first parallel section, a second parallel section and a third parallel section which are sequentially and equidistantly arranged in the same plane; the measured currents flow through the two adjacent parallel segments in equal and opposite directions.
The magneto-dependent unit comprises a first magneto resistor, a third magneto resistor and two second magneto resistors; the first magnetic resistor and one of the second magnetic resistors counteract the output of the external interference magnetic field, and the third magnetic resistor and the other of the second magnetic resistors counteract the output of the external interference magnetic field.
The distance between the first magnetic resistor and the first parallel segment, the distance between the second magnetic resistor and the second parallel segment and the distance between the third magnetic resistor and the third parallel segment are all smaller than a first threshold value; the relative positions of the first magnetic resistor and the first parallel segment, the second magnetic resistor and the second parallel segment and the third magnetic resistor and the third parallel segment are the same;
the sensitivity directions of the first magnetic resistor and the second magnetic resistor are opposite, and the sensitivity directions of the second magnetic resistor and the third magnetic resistor are opposite.
Optionally, the first magnetic resistor and one of the second magnetic resistors are connected in series or in parallel to form a first magnetic resistance component; the other second magnetic resistor and the third magnetic resistor are connected in series or in parallel to form a second magnetic resistance component; the first and second magneto resistive elements are connected in series or in parallel.
Alternatively, two of the second magnetic resistors are arranged in parallel or overlapping.
Optionally, when the first magnetic resistor, the second magnetic resistor and the third magnetic resistor are respectively arranged right above or right below the corresponding parallel segments, the included angles between the sensitive directions of the first magnetic resistor, the second magnetic resistor and the third magnetic resistor and the corresponding parallel segments are not 0 degrees, and are not 180 degrees.
Optionally, the circuit comprises four magneto-sensitive units, and the four magneto-sensitive units are connected to form a Wheatstone full-bridge circuit structure.
Optionally, the circuit comprises two magneto-sensitive units, and the two magneto-sensitive units are connected to form a Wheatstone half-bridge circuit structure.
Optionally, the types of the first magnetoresistance, the second magnetoresistance, and the third magnetoresistance include XMR including TMR, AMR, GMR, CMR or SMR.
The beneficial effects of the current sensor provided by the embodiment of the invention include, for example:
the current conductor comprises a first parallel section, a second parallel section and a third parallel section which are sequentially and equidistantly arranged in the same plane; the measured currents flow in opposite directions and are equal in magnitude in adjacent parallel segments. The magneto-sensitive unit comprises a first magneto resistor, a third magneto resistor and two second magneto resistors; the relative positions of the first magnetic resistor and the first parallel segment, the second magnetic resistor and the second parallel segment and the third magnetic resistor and the third parallel segment are the same. The first magnetic resistor and the second magnetic resistor have opposite sensitivity directions, and the second magnetic resistor and the third magnetic resistor have opposite sensitivity directions. The first magnetic resistor and one of the second magnetic resistors counteract the output of the external interference magnetic field, and the third magnetic resistor and the other of the second magnetic resistors counteract the output of the external interference magnetic field; therefore, the current sensor can counteract external field interference, sensitivity is not reduced, and measurement accuracy of current is improved.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are needed in the embodiments will be briefly described below, it being understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and other related drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic diagram of a prior art magnetoresistive junction of a current sensor;
FIG. 2 is a schematic diagram showing the distribution of magnetic resistance of another current sensor according to the prior art;
FIG. 3 is a schematic diagram of a first distribution structure of magnetic resistors in a current sensor according to an embodiment of the present invention;
FIG. 4 is a schematic diagram of a second distribution structure of magnetic resistors in a current sensor according to an embodiment of the present invention;
FIG. 5 is a schematic diagram of a third distribution structure of magnetic resistors in a current sensor according to an embodiment of the present invention;
FIG. 6 is a schematic diagram of a fourth distribution structure of magnetic resistors in a current sensor according to an embodiment of the present invention;
FIG. 7 is a schematic diagram of a first connection structure of a magnetic resistor in a current sensor according to an embodiment of the present invention;
FIG. 8 is a schematic diagram of a second connection structure of a magnetic resistor in a current sensor according to an embodiment of the present invention;
FIG. 9 is a schematic diagram of a third connection structure of a magnetic resistor in a current sensor according to an embodiment of the present invention;
FIG. 10 is a schematic diagram of a fourth connection structure of a magnetic resistor in a current sensor according to an embodiment of the present invention;
FIG. 11 is a schematic diagram of a full-bridge circuit of a current sensor according to an embodiment of the present invention;
fig. 12 is a schematic diagram of a half-bridge circuit structure of a current sensor according to an embodiment of the present invention.
Icon: 100-magnetosensitive units; 10-a first parallel segment; 110-a first magnetoresistance; 121. 122-a second magnetoresistance; 130-a third magnetoresistance; 20-a second parallel segment; 30-third parallel segment.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments of the present invention. The components of the embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations.
Thus, the following detailed description of the embodiments of the invention, as presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
It should be noted that: like reference numerals and letters denote like items in the following figures, and thus once an item is defined in one figure, no further definition or explanation thereof is necessary in the following figures.
In the description of the present invention, it should be noted that, if the terms "upper", "lower", "inner", "outer", and the like indicate an azimuth or a positional relationship based on the azimuth or the positional relationship shown in the drawings, or the azimuth or the positional relationship in which the inventive product is conventionally put in use, it is merely for convenience of describing the present invention and simplifying the description, and it is not indicated or implied that the apparatus or element referred to must have a specific azimuth, be configured and operated in a specific azimuth, and thus it should not be construed as limiting the present invention.
Furthermore, the terms "first," "second," and the like, if any, are used merely for distinguishing between descriptions and not for indicating or implying a relative importance.
It should be noted that the features of the embodiments of the present invention may be combined with each other without conflict.
The detection principle of the existing current sensor is as follows: the current flowing in the lead generates a magnetic field, and the magnetic resistors in different sensitive directions form a full-bridge circuit to induce the magnetic field generated by the current, so that corresponding current values are obtained. However, the existing current sensor is easily interfered by an external magnetic field, such as an interfering magnetic field, an ambient magnetic field and the like, and when the external magnetic field has a component perpendicular to a current plane, the external magnetic field is overlapped with a magnetic field generated by a measured current, so that the current measurement is inaccurate. At present, some anti-interference current sensors exist, but the external field interference is counteracted at the expense of the sensitivity of the sensor, so that the sensitivity of the current sensor is reduced, and the accuracy of measuring the current is reduced.
In order to solve the interference of the external magnetic field, the embodiment provides a current sensor which can effectively eliminate the influence of the interference magnetic field/the environment magnetic field and improve the measurement accuracy of the current without reducing the sensitivity of the sensor.
Referring to fig. 3, the present embodiment provides a current sensor for measuring the magnitude of a current by using a magnetosensitive unit 100 having a function of eliminating an interference magnetic field, and the current sensor includes a current conductor and the magnetosensitive unit 100. Wherein: the current conductor comprises a first parallel segment 10, a second parallel segment 20 and a third parallel segment 30 which are sequentially arranged at equal intervals L1 in the same plane; the current to be measured sequentially flows through three parallel segments of the current conductor, and the current to be measured is equal in magnitude and opposite in direction on two adjacent parallel segments. The solid arrows in the figure indicate the direction of the measured current.
The magneto-dependent cell 100 comprises four magneto-resistors, namely a first magneto-resistor 110, a third magneto-resistor 130 and two second magneto-resistors 121, 122; the first magnetic resistor 110 and one of the second magnetic resistors 121 cancel each other out the output of the external disturbing magnetic field, and the third magnetic resistor 130 and the other of the second magnetic resistors 122 cancel each other out the output of the external disturbing magnetic field.
The distance between the first magnetic resistor 110 and the first parallel segment 10, the distance between the second magnetic resistors 121 and 122 and the second parallel segment 20, and the distance between the third magnetic resistor 130 and the third parallel segment 30 are all smaller than the first threshold, i.e. the magnetic resistors are arranged near the corresponding parallel segments, so as to effectively detect the magnetic field generated by the corresponding parallel segments. The relative positions of the first magnetoresistive element 110 and the first parallel segment 10, the relative positions of the second magnetoresistive elements 121, 122 and the second parallel segment 20, and the relative positions (including orientation and distance) of the third magnetoresistive element 130 and the third parallel segment 30 are all the same. The first and second magnetic resistors 110, 121, 122 have opposite sensitivity directions, and the second and third magnetic resistors 121, 122, 130 have opposite sensitivity directions.
It should be noted that, the "same relative position" is understood to mean that the relative distance and the relative direction between each magnetoresistive element and the corresponding parallel segment are the same. For example, if the first magnetoresistive element 110 is positioned at a first distance D from the first parallel segment 10 in the first direction, the first distance D is the linear distance between the second magnetoresistive elements 121, 122 and the second parallel segment 20 in the first direction, and the first distance D is the linear distance between the third magnetoresistive element 130 and the third parallel segment 30 in the first direction. The first direction may be any direction such as upward, downward, left, right, obliquely upward or obliquely downward. In this way, the outputs of the external interference magnetic field by two magnetic resistors in two adjacent parallel segments can be mutually counteracted. The external disturbing magnetic field is an external magnetic field and comprises a uniform disturbing field and a gradient disturbing field.
Alternatively, when the first magnetic resistor 110, the second magnetic resistor 121, 122 and the third magnetic resistor 130 are respectively disposed directly above or directly below the corresponding parallel segments, the sensitivity direction of the first magnetic resistor 110, the second magnetic resistor 121, 122 and the third magnetic resistor 130 is different from 0 ° and different from 180 ° from the corresponding parallel segments.
The four magnetic resistors are connected in series/parallel. Optionally, the first magnetic resistor 110 and one of the second magnetic resistors 121 are connected in series or in parallel to form a first magnetic resistance component; the other second magnetic resistor 122 and the third magnetic resistor 130 are connected in series or in parallel to form a second magnetic resistance component; the first magneto resistive element and the second magneto resistive element are connected in series or in parallel. The two second magnetoresistors 121, 122 are arranged in parallel or overlapping. The distance between the two second magnetic resistors 121, 122 is very small, and is much smaller than the distance between the first magnetic resistor 110 and the second magnetic resistors 121, 122, and is also much smaller than the distance between the third magnetic resistor 130 and the second magnetic resistors 121, 122. In practice, it is only necessary to ensure that the magnetic fields sensed by the two second magnetoresistors 121, 122 are the same. As shown in fig. 3, 4 and 6, the two second magnetic resistors 121 and 122 are arranged in parallel, and as shown in fig. 5, the two second magnetic resistors 121 and 122 are arranged in an overlapping manner, so that the magnetic fields sensed by the two second magnetic resistors 121 and 122 can be ensured to be the same.
It will be appreciated that the three parallel segments may be connected in an S-shape or a U-shape. The sensitivity directions of the first magnetic resistor 110 and the second magnetic resistors 121 and 122 are opposite, and the magnitude and the direction of the measured current in the first parallel section 10 and the second parallel section 20 are equal, so that the magnitude and the direction of the magnetic field H generated by the measured current at the first magnetic resistor 110 and the second magnetic resistors 121 and 122 are equal. The sensitivity directions of the second magnetic resistors 121, 122 and the third magnetic resistor 130 are opposite, and the magnetic fields H generated by the measured currents at the second magnetic resistors 121, 122 and the third magnetic resistor 130 are equal in magnitude and opposite in direction. The disturbing magnetic field comprises a uniform disturbing field Hu and a gradient disturbing field Hg. Wherein the gradient disturbance field Hg refers to a varying magnetic field per unit distance.
Referring to fig. 7, the first connection of four magnetoresistors in the magnetosensitive unit 100:
if the first magnetic resistor 110 and a second magnetic resistor 121 are connected in series, a first magnetic resistance component is formed; the other second magnetic resistor 122 and the third magnetic resistor 130 are connected in series to form a second magnetic resistance component; the first magneto resistive element and the second magneto resistive element are connected in series. Assuming that the resistance of the first magneto resistor 110 is R1, the resistances of the second magneto resistors 121 and 122 are R2, and the resistance of the third magneto resistor 130 is R3, there are:
R1=R0+K（H+Hu+Hg1）；
R2=R0-K（-H+Hu+Hg2）；
r3=r0+k (h+hu+hg3); wherein R0 is the resistance of the magnetic resistor in the absence of a magnetic field, K is a constant, and H is the magnetic field generated by the measured current at the magnetic resistor; hg is the gradient interference field and Hu is the uniform interference field.
The resistance of the first magneto resistive element is R12, r12=r1+r2=2r0+2kh+k (Hg 1-Hg 2);
the resistance of the second magneto resistive element is r23, r23=r2+r3=2r0+2kh+k (Hg 3-Hg 2);
the resistance of the magnetosensitive cell 100 formed by connecting the four magnetoresistors is r123, r123=r12+r23=4r0+4kh.
As can be seen from R12 and R23, after the first magnetic resistor 110 and the second magnetic resistor 121 are connected in series, the second magnetic resistor 122 and the third magnetic resistor 130 are connected in series, and the resistances are only related to the magnetic field H and the gradient disturbance field Hg generated by the measured current, but not related to the uniform disturbance field Hu. As can be seen from R123, after the first magneto resistive element and the second magneto resistive element are connected in series, the resistance is only related to the magnetic field H generated by the measured current, and is not related to the gradient disturbance field Hg and the uniform disturbance field Hu. And the sensitivity is 4 times of the original sensitivity, and the corresponding output is also increased, namely the sensitivity is higher. Therefore, the current sensor provided by the embodiment can completely counteract the external interference, and the sensitivity is not reduced but increased.
Referring to fig. 8, the second connection mode of four magnetic resistors in the magnetosensitive unit 100:
if the first magnetic resistor 110 and a second magnetic resistor 121 are connected in parallel, a first magnetic resistance component is formed; the other second magnetic resistor 122 and the third magnetic resistor 130 are connected in parallel to form a second magnetic resistance component; the first magneto resistive element and the second magneto resistive element are connected in parallel. Assuming that the conductance of the first magnetic resistor 110 is G1, the conductance of the second magnetic resistors 121 and 122 is G2, and the conductance of the third magnetic resistor 130 is G3, there are:
G1=G0+K（H+Hu+Hg1）；
G2=G0-K（-H+Hu+Hg2）；
g3 G0+k (h+hu+hg3); wherein G0 is the conductance value of the magnetic resistor in the absence of a magnetic field, K is a constant, and H is the magnetic field generated by the measured current at the magnetic resistor; hg is the gradient interference field and Hu is the uniform interference field.
The conductance of the first magneto resistive element is g12, g12=g1+g2=2g0+2kh+k (Hg 1-Hg 2);
the conductance of the second magneto resistive element is g23, g23=g2+g3=2g0+2kh+k (Hg 3-Hg 2);
since the distance between the first magnetic resistor 110 and the second magnetic resistor 121, and the distance between the second magnetic resistor 122 and the third magnetic resistor 130 are equal, and the second magnetic resistors 121 and 122 can be regarded as being at the same spatial position, the conductance of the magnetosensitive cell 100 formed by connecting the four magnetic resistors is g123, g123=g12+g23=4g0+4kh.
As can be seen from G12 and G23, after the first magnetic resistor 110 and the second magnetic resistor 121 are connected in series, the second magnetic resistor 122 and the third magnetic resistor 130 are connected in series, and the conductance is only related to the magnetic field H and the gradient disturbance field Hg generated by the measured current, but not related to the uniform disturbance field Hu. As can be seen from G123, after the first magneto resistive element and the second magneto resistive element are connected in series, the conductance is only related to the magnetic field H generated by the measured current, and is independent of the gradient disturbance field Hg and the uniform disturbance field Hu. And the sensitivity is 4 times of the original sensitivity, and the corresponding output is also increased, namely the sensitivity is higher. Therefore, the current sensor provided by the embodiment can completely counteract the external interference, and the sensitivity is not reduced but increased.
For the magneto resistor employing the TMR effect, the resistance value and the conductance value of the magneto resistor may be expressed in the form of a+b×h, except for a and B of the resistance and conductance expressions. Therefore, the series connection can adopt resistance calculation and the parallel connection can adopt conductance calculation, the obtained results are consistent, the results are only related to the magnetic field H generated by the tested current, the results are not related to the gradient interference field Hg and the uniform interference field Hu, the sensitivity is 4 times of the original sensitivity, and the output is increased.
In another embodiment, as shown in FIG. 9, a first magneto-resistive element 110 and a second magneto-resistive element 121 are connected in series to form a first magneto-resistive element; the other second magnetic resistor 122 and the third magnetic resistor 130 are connected in series to form a second magnetic resistance component; the first magneto resistive element and the second magneto resistive element are connected in parallel. Assuming that the resistance of the first magneto resistor 110 is R1, the resistances of the second magneto resistors 121 and 122 are R2, and the resistance of the third magneto resistor 130 is R3, there are:
R1=R0+K（H+Hu+Hg1）；
R2=R0-K（-H+Hu+Hg2）；
r3=r0+k (h+hu+hg3); wherein R0 is the resistance of the magnetic resistor in the absence of a magnetic field, K is a constant, and H is the magnetic field generated by the measured current at the magnetic resistor; hg is the gradient interference field and Hu is the uniform interference field.
The resistance of the first magneto resistive element is R12, r12=r1+r2=2r0+2kh+k (Hg 1-Hg 2);
the resistance of the second magneto resistive element is r23, r23=r2+r3=2r0+2kh+k (Hg 3-Hg 2);
the distance between the first and second magnetic resistors 110, 121, and the distance between the second and third magnetic resistors 122, 130 are equal, and the second magnetic resistors 121, 122 can be considered to be at the same spatial location. The resistances of the first magnetic resistance component and the second magnetic resistance component are respectively converted into a conductive form, and after the resistances are expanded in a Taylor series and then the resistances are reserved for one time:
the conductance of the first magneto resistive component is g12, g12=g+ kK (Hg 1-Hg 2);
the conductance of the second magneto resistive component is g23, g23=g+ kK (Hg 3-Hg 2);
wherein,k is a first order coefficient of the Taylor series expansion of the conductance of the first magnetic resistance component and the second magnetic resistance component. The conductance of the magnetosensitive cell 100 formed by the connection of the four magnetoresistors is g123, g123=g12+g23=2g.
Of course, the four magnetic resistors are connected in series-parallel, and other connection modes besides the above listed situations exist, as shown in fig. 10, the first magnetic resistor 110 and one second magnetic resistor 121 are connected in parallel to form a first magnetic resistance component; the other second magnetic resistor 122 and the third magnetic resistor 130 are connected in parallel to form a second magnetic resistance component; the first magneto resistive element and the second magneto resistive element are connected in series. The settlement results are the same for the case of fig. 10 or other connections, and are independent of the gradient disturbance field Hg and the uniform disturbance field Hu, and are not calculated one by one.
It is noted that the distance between the individual magneto resistances is short relative to the spatial distance of the current sensor, and that in addition to the magnetic field, the uniform disturbing field and the gradient disturbing field generated by the current, there are some other relatively small amounts of disturbing fields. At the boundaries where the magnetic field does not produce abrupt changes, other inhomogeneous fields can be approximated to the gradient disturbing field treatment, i.e. these other disturbing fields with smaller inhomogeneous amounts can be approximated to the gradient disturbing field treatment in the above calculations.
Optionally, the types of the first magneto resistor 110, the second magneto resistors 121, 122 and the third magneto resistor 130 include XMR including TMR, AMR, GMR, CMR or SMR, which are not particularly limited herein.
Referring to fig. 11, on the basis of the magneto-sensitive units 100, the current sensor may be implemented to include four magneto-sensitive units 100, i.e., A, B, C, D connected to form a wheatstone full-bridge circuit structure, and output linearly. The magneto-resistors of the magneto-sensitive unit A, B are respectively used as two bridge arms of one pair of arms of the wheatstone bridge, and the magneto-sensitive unit C, D is respectively used as two bridge arms of the other pair of arms of the wheatstone bridge. As shown by short arrows corresponding to the respective magnetosensitive units 100 in fig. 10, the directions of sensitivity of the magnetosensitive units 100 (magnetosensitive units a and B, magnetosensitive units C and D) on the same pair of arms are the same, and the directions of sensitivity of the magnetosensitive units 100 on different pairs of arms are opposite. The direction of the magnetic field generated by the current to be measured is shown by a long arrow H in the figure.
In other embodiments, as in fig. 12, the current sensor may be implemented to include two magnetosensitive cells 100, with the two magnetosensitive cells 100 connected to form a wheatstone half-bridge circuit configuration. The sensitivity directions of the two magnetosensitive units 100 are opposite.
In summary, the current sensor provided by the embodiment of the invention has the following beneficial effects:
the current sensor provided by the embodiment of the invention comprises a current conductor, a first parallel section 10, a second parallel section 20 and a third parallel section 30 which are sequentially and equidistantly arranged in the same plane; the measured currents flow in opposite directions and are equal in magnitude in adjacent parallel segments. The magneto-dependent cell 100 comprises a first magneto-resistor 110, a third magneto-resistor 130 and two second magneto-resistors 121, 122; the relative positions of the first magneto resistor 110 and the first parallel segment 10, the second magneto resistors 121, 122 and the second parallel segment 20, and the third magneto resistor 130 and the third parallel segment 30 are the same. The first and second magnetic resistors 110, 121, 122 have opposite sensitivity directions, and the second and third magnetic resistors 121, 122, 130 have opposite sensitivity directions. The first magnetic resistor 110 and one of the second magnetic resistors 121 and 122 counteract the output of the external disturbing magnetic field, and the third magnetic resistor 130 and the other of the second magnetic resistors 121 and 122 counteract the output of the external disturbing magnetic field; therefore, the current sensor can offset the external field interference, the sensitivity is not reduced, the sensitivity can be increased to four times of the original sensitivity, and the current sensor is favorable for improving the measurement accuracy of the current.
In the current sensor, each magneto-resistance in each magneto-sensitive unit 100 is flexibly connected in series and parallel, and the current sensor can be realized as a Wheatstone half-bridge circuit structure formed by two magneto-sensitive units 100 or as a Wheatstone full-bridge circuit structure formed by four magneto-sensitive units 100.
The foregoing is merely illustrative of the present invention, and the present invention is not limited thereto, and any changes or substitutions easily contemplated by those skilled in the art within the scope of the present invention should be included in the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.
Claims (7)
1. A current sensor for measuring the magnitude of a current using a magnetosensitive cell having a function of eliminating an interfering magnetic field, said current sensor comprising:
the current conductor comprises a first parallel section, a second parallel section and a third parallel section which are sequentially and equidistantly arranged in the same plane; the measured currents flow through the two adjacent parallel segments in equal and opposite directions;
the magneto-dependent unit comprises a first magneto-resistor, a third magneto-resistor and two second magneto-resistors; the first magnetic resistor and one of the second magnetic resistors counteract the output of the external interference magnetic field, and the third magnetic resistor and the other of the second magnetic resistors counteract the output of the external interference magnetic field;
the distance between the first magnetic resistor and the first parallel segment, the distance between the second magnetic resistor and the second parallel segment and the distance between the third magnetic resistor and the third parallel segment are all smaller than a first threshold value; the relative positions of the first magnetic resistor and the first parallel segment, the second magnetic resistor and the second parallel segment and the third magnetic resistor and the third parallel segment are the same;
the sensitivity directions of the first magnetic resistor and the second magnetic resistor are opposite, and the sensitivity directions of the second magnetic resistor and the third magnetic resistor are opposite.
2. The current sensor of claim 1, wherein the first magnetoresistive element and one of the second magnetoresistive elements are connected in series or in parallel to form a first magnetoresistive element; the other second magnetic resistor and the third magnetic resistor are connected in series or in parallel to form a second magnetic resistance component; the first and second magneto resistive elements are connected in series or in parallel.
3. The current sensor of claim 1, wherein two of the second magnetoresistors are disposed in parallel or overlapping.
4. The current sensor of claim 1, wherein the first, second, and third magnetic resistors are disposed directly above or directly below the corresponding parallel segment, respectively, and the first, second, and third magnetic resistors have a sensitivity direction that is not at an angle of 0 ° and not at an angle of 180 ° to the corresponding parallel segment.
5. The current sensor of claim 1, comprising four of said magnetosensitive cells connected to form a wheatstone full bridge circuit configuration.
6. The current sensor of claim 1, comprising two of said magnetosensitive cells connected to form a wheatstone half-bridge circuit configuration.
7. The current sensor according to any one of claims 1 to 6, wherein the types of the first, second, and third magneto-resistors include XMR including TMR, AMR, GMR, CMR or SMR.
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