A current sensor

Abstract

The present invention discloses a current sensor, comprising: at least three magnetic sensor units, arranged around a region to be detected, the region to be detected being used to pass through a wire to be detected; each magnetic sensor unit comprising: a first magnetic resistor; a second magnetic resistor, connected in series with the first magnetic resistor, the two ends of the series connection being respectively connected to the two ends of a power supply; wherein the magnetic sensitivity direction of the second magnetic resistor is opposite to that of the first magnetic resistor; the output end of each magnetic sensor unit is arranged between the first magnetic resistor and the second magnetic resistor; the output end of each magnetic sensor unit is connected to the output end of at least one of the other magnetic sensor units. In the current sensor provided by the embodiment of the present invention, the magnetic resistors in the multiple magnetic sensor units are actually arranged in parallel, and even if one magnetic sensor unit is damaged, the remaining magnetic sensors can still work normally and output measurement results.

Description

Technical Field

[0001] The present invention relates to the technical field of sensors, and in particular to a current sensor. Background Art

[0002] Current sensors are widely used in new energy, intelligent transportation, industrial control, smart home appliances, smart grids and other fields.

[0003] like Figure 1 As shown, the prior art discloses a current sensor, in which a plurality of magnetic sensor units are arranged around the conductor to be measured, each magnetic sensor unit includes a first magnetic resistor and a second magnetic resistor with opposite magnetic sensitivity directions, and adjacent magnetic resistors are connected end to end to form a sensor chain arranged in series, and the two ends of the sensor chain serve as output ends of the current sensor.

[0004] However, if one magnetic resistor in the series sensor chain is damaged, the entire current sensor will be unable to output measurement results. Summary of the invention

[0005] In view of this, an embodiment of the present invention provides a current sensor to solve the problem that damage to one magnetoresistance in the existing current sensor may cause the entire current sensor to be unable to output a measurement result.

[0006] An embodiment of the present invention provides a current sensor, comprising: at least three magnetic sensor units, which are arranged around a to-be-detected area, and the to-be-detected area is used to pass a to-be-detected wire; each magnetic sensor unit comprises: a first magnetic resistor; a second magnetic resistor, which is connected in series with the first magnetic resistor, and two ends of the series connection are respectively connected to two ends of a power supply; wherein the magnetic sensitivity direction of the second magnetic resistor is opposite to that of the first magnetic resistor; the output end of each magnetic sensor unit is arranged between the first magnetic resistor and the second magnetic resistor; the output end of each magnetic sensor unit is connected to the output end of at least one of the other magnetic sensor units.

[0007] Optionally, output ends of the at least three sensor units are connected.

[0008] Optionally, the current sensor further includes: a first operational amplifier, the output ends of the at least three magnetic sensor units are connected to a first input end of the first operational amplifier, and a second input end of the first operational amplifier is connected to a reference voltage.

[0009] Optionally, the at least three magnetic sensor units include a first magnetic sensor unit and a second magnetic sensor unit, wherein the magnetic sensitivity directions of the magnetic resistors connected to the same potential source in the first magnetic sensor unit and the second magnetic sensor unit are opposite; the first magnetic sensor unit and the second magnetic sensor unit are arranged around the area to be detected in an interlaced manner; the output ends of the first magnetic sensors are connected, and the output ends of the second magnetic sensors are connected.

[0010] Optionally, the current sensor also includes: a second operational amplifier, the output ends of the first magnetic sensor units are connected to the first input end of the second operational amplifier, and the second input end of the second operational amplifier is connected between the first magnetic resistor and the second magnetic resistor in each second magnetic sensor unit.

[0011] Optionally, each magnetic sensor unit also includes: a third magnetic resistor; a fourth magnetic resistor, which is connected in series with the third magnetic resistor, and the two ends of the series connection are respectively connected to the two ends of the power supply; wherein the magnetic sensitivity direction of the fourth magnetic resistor is opposite to that of the third magnetic resistor; in each magnetic sensor unit, the magnetic sensitivity directions of the magnetic resistors connected to the same potential source are opposite; the first output end of the magnetic sensor unit is arranged between the first magnetic resistor and the second magnetic resistor, and the second output end is arranged between the third magnetic resistor and the fourth magnetic resistor; the first output ends of each magnetic sensor unit are connected, and the second output ends are connected.

[0012] Optionally, the current sensor further includes: a third operational amplifier, wherein the first output end of each magnetic sensor unit is connected to the first input end of the third operational amplifier, and the second output end of each magnetic sensor unit is connected to the second input end of the third operational amplifier.

[0013] Optionally, the at least three magnetic sensor units are evenly arranged around the area to be detected according to a predetermined geometric pattern, and the predetermined geometric pattern includes a circle, an ellipse or a centrally symmetrical polygon.

[0014] In the current sensor provided by the embodiment of the present invention, each magnetic sensor unit is respectively connected to two ends of a power supply, and the output end of the magnetic sensor unit is arranged between the first magnetic resistor and the second magnetic resistor, so that the magnetic resistors in the multiple magnetic sensor units are actually arranged in parallel. Even if one magnetic sensor unit is damaged, the remaining magnetic sensors can still work normally and output measurement results. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The features and advantages of the present invention will be more clearly understood by referring to the accompanying drawings, which are schematic and should not be construed as limiting the present invention in any way. In the accompanying drawings:

[0016] Figure 1A schematic diagram of a current sensor in the prior art is shown;

[0017] Figure 2 A schematic diagram of a current sensor according to an embodiment of the present invention is shown;

[0018] Figure 3 A schematic diagram of another current sensor according to an embodiment of the present invention is shown;

[0019] Figure 4 A schematic diagram of a signal processing module according to an embodiment of the present invention is shown;

[0020] Figure 5 A simulation schematic diagram is shown;

[0021] Figure 6 Shown according to Figure 5 The results of simulation in the manner shown;

[0022] Figure 7 Another simulation schematic diagram is shown;

[0023] Figure 8 Shown according to Figure 7 The results of simulation in the manner shown;

[0024] Fig. 9 A schematic diagram of another current sensor according to an embodiment of the present invention is shown;

[0025] Fig.10 A schematic diagram of another signal processing module according to an embodiment of the present invention is shown;

[0026] Fig.11 A schematic diagram of another current sensor according to an embodiment of the present invention is shown;

[0027] Fig.12 A schematic diagram of another signal processing module according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0029] In the current sensor provided by the embodiment of the present invention, each magnetic sensor unit is respectively connected to two ends of a power supply, and the output end of the magnetic sensor unit is arranged between the first magnetic resistor and the second magnetic resistor, so that the magnetic resistors in the multiple magnetic sensor units are actually arranged in parallel. Even if one magnetic sensor unit is damaged, the remaining magnetic sensors can still work normally and output measurement results.

[0030] In addition, in the current sensor provided by the embodiment of the present invention, the magnetic sensor units are arranged around the area to be detected, and the area to be detected is used to pass the wire to be tested. According to the "Ampere's loop theorem of the magnetic field": the line integral of the magnetic induction intensity B along any closed path is equal to the algebraic sum of the currents surrounded by the closed path multiplied by the magnetic permeability", that is, ∮B·dl=μI. The current sensor provided by the embodiment of the present invention measures the magnetic induction intensity at the position of the wire to be tested by means of magnetic sensors arranged around the wire to be tested, and obtains the line integral of the magnetic induction intensity along the closed path around the wire to be tested in a discretized manner, so that the current value of the wire to be tested surrounded by the closed path can be obtained, and the measurement value of the current sensor is not affected by the position error of the wire to be tested, nor is it interfered by the external magnetic field (the measurement value is only related to the current value in the closed figure).

[0031] Embodiment 1

[0032] The embodiment of the present invention provides a current sensor, such as Figure 2 and Figure 3 As shown, at least three magnetic sensor units are arranged around the area to be detected, and the area to be detected is used to pass the wire to be tested. Each magnetic sensor unit includes a first magnetic resistor and a second magnetic resistor, the first magnetic resistor and the second magnetic resistor are connected in series, and the two ends of the series connection are respectively connected to the two ends of the power supply, and the magnetic sensitivity direction of the second magnetic resistor is opposite to that of the first magnetic resistor. The output end of each magnetic sensor unit is arranged between the first magnetic resistor and the second magnetic resistor. The output ends of these magnetic sensor units are connected.

[0033] like Figure 2 and Figure 3As shown, the magnetic sensor units 10a-10h are arranged around the conductor A to be tested in a closed shape, and the closed shape can be a circle, an ellipse or a centrally symmetrical polygon. The magnetic sensor unit 10a includes a first magnetic resistor 11a and a second magnetic resistor 12a. The resistance of the first magnetic resistor 11a increases with the increase of the magnetic induction intensity at its location (i.e., the positive sensitive direction), and the resistance of the second magnetic resistor 12a decreases with the increase of the magnetic induction intensity at its location (i.e., the negative sensitive direction); or, the resistance of the first magnetic resistor 11a decreases with the increase of the magnetic induction intensity at its location (i.e., the negative sensitive direction), and the resistance of the second magnetic resistor 12a increases with the increase of the magnetic induction intensity at its location (i.e., the positive sensitive direction). The remaining magnetic sensor units 10b-10h are also arranged in this way. The output terminals Vo of the magnetic sensors 10a-10h are connected together.

[0034] The output ends of the current sensor provided in the embodiment of the present invention are connected, which can also better suppress the error caused by the position deviation of the measured wire or the external uniform magnetic field. The reasons are as follows:

[0035] For example, the magnetic sensor units are arranged in a circular array around the wire to be tested with the area to be tested as the center. Assume that the resistance of the first magnetic resistor is R1 = R0 + k·B i , where R0 is the resistance of the first magnetoresistance when the magnetic induction intensity is zero, B i is the magnetic induction intensity at the location of the first magnetic resistor, k is the rate of change of the first magnetic resistor; the resistance of the second magnetic resistor is R2 = R0-k·B j , where R0 is the resistance of the second magnetoresistance when the magnetic induction intensity is zero (when the magnetic induction intensity is zero, the resistance of the first magnetoresistance is equal to that of the second magnetoresistance), B j is the magnetic induction intensity at the location of the second magnetic resistor, and k is the rate of change of the second magnetic resistor. Then the signal output after the output ends of all magnetic sensor units are connected is

[0036]

[0037] Wherein, Vcc is the power supply voltage (ie, VCC in the drawings of the present application), and n is the number of magnetic sensor units.

[0038] If the conductor to be tested is located at the center of the circular array without offset, the magnetic induction intensity at each magnetic sensor unit is equal, assuming it is B0, then the output can be simplified to

[0039]

[0040] If the conductor to be tested deviates from the center of the circle or is affected by an external uniform magnetic field,

[0041]

[0042] Among them, δB i is the change in magnetic induction intensity when the i-th magnetic sensor unit is not offset from the measured wire. Since R0 is much larger than the resistance change k·B, the first-order approximation of formula (3) is

[0043]

[0044] in, is the average value of the change in magnetic induction intensity at the location of n magnetic sensor units. Here, So we can get That is, the connection of the output ends of the current sensor provided by the embodiment of the present invention can better suppress the error caused by the position deviation of the conductor to be measured or the external uniform magnetic field.

[0045] In addition, in terms of experimental data, according to the above formula (1), the magnetic sensor units are arranged in a circle with a radius of 25 cm, and the position of the wire to be tested deviates from the center of the circle by a certain position (such as Figure 5 The relationship between the position offset and the measurement error of the current sensor can be obtained as shown in the following figure. Figure 6 As shown. Figure 6 It can be seen that connecting the output ends of the magnetic sensor units so that multiple magnetic resistors are connected in parallel can better suppress the error caused by the position offset of the conductor to be measured, and the more magnetic sensor units there are, the better the effect of suppressing the error.

[0046] In addition, according to the above formula (1), there is a wire with the same current next to the wire to be tested, and the two wires are 50mm apart (such as Figure 7 ) to simulate, the error caused by the external wire is as follows Figure 8 As shown in FIG8 , it can be seen that the output ends of the magnetic sensor units are connected so that multiple magnetic resistors are connected in parallel, which can better suppress the error caused by the magnetic field generated by the external current, and the more magnetic sensor units there are, the better the effect of suppressing the error.

[0047] It should be noted that the output terminals Vo of the magnetic sensors 10a-10h can be directly used as output terminals after being connected. Alternatively, as an optional implementation of this embodiment, Figure 4 As shown, the output terminal Vo is connected to the first input terminal of the first operational amplifier, and the second input terminal of the first operational amplifier is connected to the reference voltage Vref. Amplifying the output signal Vo by the operational amplifier can make its value easier to obtain.

[0048] Embodiment 2

[0049] The embodiment of the present invention provides a current sensor, such as Fig. 9As shown, at least three magnetic sensor units are arranged around the area to be detected, and the area to be detected is used to pass the wire to be detected. Each magnetic sensor unit includes a first magnetic resistor and a second magnetic resistor, the first magnetic resistor and the second magnetic resistor are connected in series, and the two ends of the series connection are respectively connected to the two ends of the power supply, and the magnetic sensitivity direction of the second magnetic resistor is opposite to that of the first magnetic resistor. The output end of each magnetic sensor unit is set between the first magnetic resistor and the second magnetic resistor.

[0050] The at least three magnetic sensor units include a first magnetic sensor unit and a second magnetic sensor unit, wherein the magnetic sensitivity directions of the magnetic resistors connected to the same potential source in the first magnetic sensor unit and the second magnetic sensor unit are opposite. The first magnetic sensor unit and the second magnetic sensor unit are arranged around the area to be detected in an interlaced manner. The output ends of the first magnetic sensors are connected, and the output ends of the second magnetic sensors are connected.

[0051] like Fig. 9 As shown, 11x in 10x is the first magnetic resistor, 12x is the second magnetic resistor, and x is any one of ah. Among the magnetic sensor units 10a-10h, 10a, 10c, 10e, and 10g are first magnetic sensor units, whose first magnetic resistors are in the positive magnetic sensitive direction and are all connected to VCC (i.e., the first potential source), and whose second magnetic resistors are in the negative magnetic sensitive direction and are all connected to GND (i.e., the second potential source); 10b, 10d, 10f, and 10h are second magnetic sensor units, whose first magnetic resistors are in the negative magnetic sensitive direction and are all connected to VCC (i.e., the first potential source), and whose second magnetic resistors are in the positive magnetic sensitive direction and are all connected to GND (i.e., the second potential source), which is opposite to the first magnetic sensor unit.

[0052] It should be noted that after the output ends of the first magnetic sensor unit and the second magnetic sensor unit in the current sensor provided in the embodiment of the present invention are connected, they can be connected to modules such as a digital signal processor, an embedded processor, or connected to an operational amplifier to process the first magnetic sensor output signal and the second magnetic sensor output signal to obtain a difference signal as the output value of the current sensor.

[0053] When connected to an operational amplifier, such as Fig.10 As shown, after the output terminals of the first magnetic sensor units are connected ( Fig. 9 The output terminal of the second magnetic sensor unit is connected to the first input terminal of the second operational amplifier. Fig. 9 Vo2 in the figure is connected to the second input terminal of the second operational amplifier. The operational amplifier is configured as a differential amplifier, which can amplify and output the difference between the signals at the first input terminal and the second input terminal.

[0054] The output terminals of the current sensor provided by the embodiment of the present invention are connected, which can effectively suppress the error caused by the position deviation of the measured wire or the external uniform magnetic field. Please refer to the first embodiment for details. The difference is that the output voltage of the current sensor provided by the embodiment of the present invention is Vo2-Vo1=2*(Vo-Vcc / 2).

[0055] Embodiment 3

[0056] The embodiment of the present invention provides a current sensor, such as Fig.11 As shown, at least three magnetic sensor units are arranged around the area to be detected, and the area to be detected is used to pass the wire to be detected. Each magnetic sensor unit includes a first magnetic resistor and a second magnetic resistor, the first magnetic resistor and the second magnetic resistor are connected in series, and the two ends of the series connection are respectively connected to the two ends of the power supply, and the magnetic sensitivity direction of the second magnetic resistor is opposite to that of the first magnetic resistor. The output end of each magnetic sensor unit is set between the first magnetic resistor and the second magnetic resistor.

[0057] Each magnetic sensor unit also includes a third magnetic resistor and a fourth magnetic resistor, which are connected in series, and the two ends of the series connection are respectively connected to the two ends of the power supply. Among them, the magnetic sensitivity direction of the fourth magnetic resistor is opposite to that of the third magnetic resistor. In each magnetic sensor unit, the magnetic sensitivity directions of the magnetic resistors connected to the same potential source are opposite. The first output end of the magnetic sensor unit is arranged between the first magnetic resistor and the second magnetic resistor, and the second output end is arranged between the third magnetic resistor and the fourth magnetic resistor. The first output ends of each magnetic sensor unit are connected, and the second output ends are connected.

[0058] like Fig.11 As shown, the magnetic sensor units 20a-20d are arranged around the area to be detected. Taking the magnetic sensor unit 20y as an example (where y can be a, b, c or d), it includes a first magnetic resistor 21y, a second magnetic resistor 22y, a third magnetic resistor 23y and a fourth magnetic resistor 24y. The first magnetic resistor 21y and the fourth magnetic resistor 24y are both in positive magnetic sensitive directions, and the second magnetic resistor 22y and the third magnetic resistor 23y are both in negative magnetic sensitive directions. The first magnetic resistor 21y and the third magnetic resistor 23y are connected to the same potential source (VCC), and the second magnetic resistor 22y and the fourth magnetic resistor 24y are connected to the same potential source (GND). The first output terminal is arranged between the first magnetic resistor 21y and the second magnetic resistor 22y, and the second output terminal is arranged between the third magnetic resistor 23y and the fourth magnetic resistor 24y. The first output terminal of each magnetic sensor unit is connected to ( Fig.11 The second output terminal of each magnetic sensor unit is connected to ( Fig.11 V- in.

[0059] It should be noted that in the current sensor provided by the embodiment of the present invention, after the first output end of the magnetic sensor unit is connected and the second output end is connected, it can be connected to a module such as a digital signal processor, an embedded processor, or connected to an operational amplifier to process the signals of the first output end of the magnetic sensor unit and the second output end of the magnetic sensor unit to obtain a difference signal as the output value of the current sensor.

[0060] When connected to an operational amplifier, such as Fig.12 As shown, after the first output terminals of the magnetic sensor units are connected ( Fig.11 The V+ in the magnetic sensor is connected to the first input terminal of the third operational amplifier, and the second output terminal of the magnetic sensor unit is connected ( Fig.11 The V- in the figure is connected to the second input terminal of the third operational amplifier. The operational amplifier is configured as a differential amplifier, which can amplify and output the difference between the signals at its first input terminal and the second input terminal.

[0061] The output ends of the current sensor provided in the embodiment of the present invention are connected, which can better suppress the error caused by the position deviation of the measured wire or the external uniform magnetic field. Please refer to the first embodiment for details. The difference is that the output voltage V+-V-=2*(Vo-Vcc / 2) of the current sensor provided in the embodiment of the present invention.

[0062] Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations are all within the scope defined by the appended claims.

Claims

1. A current sensor, characterized in that: include: At least three magnetic sensor units are arranged around an area to be detected, and the area to be detected is used for passing a wire to be detected; Each magnetic sensor unit consists of: first magnetoresistance; A second magnetic resistor is connected in series with the first magnetic resistor, and two ends of the series connection are respectively connected to two ends of the power supply; wherein the magnetic sensitivity direction of the second magnetic resistor is opposite to that of the first magnetic resistor; and the output end of each magnetic sensor unit is arranged between the first magnetic resistor and the second magnetic resistor; The output terminal of each magnetic sensor unit is connected to the output terminal of at least one of the other magnetic sensor units; The output ends of the at least three sensor units are connected; or, the at least three magnetic sensor units include a first magnetic sensor unit and a second magnetic sensor unit, wherein the magnetic sensitivity directions of the magnetic resistors connected to the same potential source in the first magnetic sensor unit and the second magnetic sensor unit are opposite, and the first magnetic sensor unit and the second magnetic sensor unit are arranged around the area to be detected in an interlaced manner; the output ends of the first magnetic sensors are connected, and the output ends of the second magnetic sensors are connected.

2. The current sensor according to claim 1, characterized in that: The current sensor also includes: A first operational amplifier, wherein the output terminals of the at least three magnetic sensor units are connected to a first input terminal of the first operational amplifier, and a second input terminal of the first operational amplifier is connected to a reference voltage.

3. The current sensor according to claim 1, characterized in that: The current sensor also includes: A second operational amplifier, wherein the output ends of the first magnetic sensor units are connected to a first input end of the second operational amplifier, and a second input end of the second operational amplifier is connected between the first magnetic resistor and the second magnetic resistor in each second magnetic sensor unit.

4. The current sensor according to any one of claims 1 to 3, characterized in that: The at least three magnetic sensor units are evenly arranged around the area to be detected according to a predetermined geometric pattern, and the predetermined geometric pattern includes a circle, an ellipse or a centrally symmetrical polygon.

5. A current sensor, characterized in that: include: At least three magnetic sensor units are arranged around an area to be detected, and the area to be detected is used for passing a wire to be detected; Each magnetic sensor unit consists of: first magnetoresistance; A second magnetic resistor is connected in series with the first magnetic resistor, and two ends of the series connection are respectively connected to two ends of the power supply; wherein the magnetic sensitivity direction of the second magnetic resistor is opposite to that of the first magnetic resistor; and the output end of each magnetic sensor unit is arranged between the first magnetic resistor and the second magnetic resistor; The output terminal of each magnetic sensor unit is connected to the output terminal of at least one of the other magnetic sensor units; Each magnetic sensor unit also includes: The third magnetoresistance; A fourth magnetic resistor is connected in series with the third magnetic resistor, and two ends of the series connection are respectively connected to two ends of the power supply; wherein the magnetic sensitivity direction of the fourth magnetic resistor is opposite to that of the third magnetic resistor; In each magnetic sensor unit, the magnetic sensitivity directions of the magnetic resistors connected to the same potential source are opposite; The first output end of the magnetic sensor unit is arranged between the first magnetic resistor and the second magnetic resistor, and the second output end is arranged between the third magnetic resistor and the fourth magnetic resistor; The first output terminals of each magnetic sensor unit are connected to each other, and the second output terminals are connected to each other.

6. The current sensor according to claim 5, characterized in that: The current sensor also includes: A third operational amplifier, wherein the first output terminals of each magnetic sensor unit are connected to the first input terminal of the third operational amplifier, and the second output terminals of each magnetic sensor unit are connected to the second input terminal of the third operational amplifier.

7. The current sensor according to any one of claims 5 to 6, characterized in that: The at least three magnetic sensor units are evenly arranged around the area to be detected according to a predetermined geometric pattern, and the predetermined geometric pattern includes a circle, an ellipse or a centrally symmetrical polygon.

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