Superparamagnetic transducer for measuring direct current and corresponding magnetic field flow sensor

Abstract

The invention relates to a superparamagnetic (SPM) transducer comprising: - a rigid body (10) having a longitudinal central axis (X) and two planar surfaces (101, 102) at each of the opposite ends of the body (10) in the direction of the longitudinal central axis (X), the two planar surfaces (101, 102) being substantially perpendicular to the longitudinal central axis (X); - at least one support channel (103) formed in the body (10) and accommodating a SPM coil (2), the support channel (103) extending parallel to the longitudinal central axis (X) and being open to the two planar surfaces (101, 102), the SPM coil (2) being formed by a core based on a SPM material around which at least one electrical conductor is wound. Furthermore, a feedback winding (3) is formed by an electrical conductor along the longitudinal central axis (X) and wound on an outer surface of the body (10).

Description

Technical Field

[0001] This invention relates to the field of non-contact measurement of current by measuring the flow rate of the magnetic field caused by the current flowing in a conductor. More specifically, this invention relates to a superparamagnetic transducer and a magnetic field flow sensor incorporating at least one transducer made of a superparamagnetic material, suitable for measuring direct current. Background Technology

[0002] To measure a current I, different physical principles can be used to generate physical quantities that represent that current I. For example, a magnetic sensor uses a transducer that is sensitive to magnetic quantities (such as the magnetic field flux caused by the current to be measured).

[0003] In particular, current sensors are known to implement so-called Effect technology, such as that described in document FR2891917. A significant feature of this technology is the use of a transducer consisting of coils, the core of which is made of a composite material loaded with nanoparticles exhibiting superparamagnetic (SPM) properties.

[0004] Traditionally, such superparamagnetic (SPM) transducers are formed from wire conductors wound around and along a flexible, elongated magnetic core. The winding created along the core serves a dual function as both an excitation coil and a measurement coil. Nevertheless, it is customary to implement suitable feedback methods to maintain the magnetic field flux in the core at approximately zero. The excitation coil can be used to provide the feedback function, but a specific winding superimposed on the excitation winding can also be provided to act as a feedback coil.

[0005] Using this type of transducer has the advantage of no magnetic deflection because SPM material has the remarkable characteristic of being hysteresis-free.

[0006] However, SPM materials have the characteristic that a compromise must be made between measurement dynamics and sensitivity. In fact, the M(H) magnetization of SPM materials roughly follows the Langevin function.

[0007] Figure 1 The primary field H (A / m) and measurement field H are shown for an open-loop sensor based on a known SPM material. mes The relationship between (A / m). In Figure 1 In the illustrated case, it can be observed that the linear range is very small, and the relationship is not bijective, with each measured field value corresponding to two original field values. Figure 1 In the example shown, the linear range (and therefore the measurement range) is limited to H. max =1100A / m.

[0008] Therefore, using low Hmax SPM materials with values ​​(e.g., 1100 A / m) can achieve good sensitivity levels, but the measurement range is still limited, so they are not suitable for measuring field flow rates with large field variations along the measurement perimeter.

[0009] However, using a higher H max Materials with values ​​(e.g., 10 kA / m) can achieve a wider linear range, but this will reduce the transducer's sensitivity, making them unsuitable for measuring small currents.

[0010] Document EP3477311B1 proposes a current sensor comprising a magnetic circuit formed around a primary conductor, a detection coil arranged on the magnetic circuit, and a secondary winding in the magnetic circuit that generates a magnetic field in the opposite direction to the magnetic field generated by the flux of the primary current. This current sensor is relatively large and cannot adequately perform any accurate measurements (one or more).

[0011] Document US2012 / 038360A1 proposes a sensor for a current flowing in an electrical conductor. This sensor comprises a superparamagnetic core forming a closed loop, which includes a U-shaped core and a ring; both elements are detachable to allow insertion of a conductor into the magnetic circuit. For operation, the sensor requires a core with a large cross-section and a high concentration of SPM material (i.e., a large amount of SPM material), making it a very expensive solution.

[0012] Document WO2022 / 129732A1 proposes a current sensor comprising a pair of coils, each coil including a superparamagnetic core. This sensor also includes three devices for energizing the coils, making it cumbersome to manufacture. Furthermore, the measurement accuracy of this sensor is unsatisfactory. Summary of the Invention

[0013] Therefore, the object of the present invention is to provide an alternative configuration for a DC current or direct magnetic field flow sensor made of SPM.

[0014] In particular, the present invention aims to propose a configuration that takes advantage of the interesting characteristics of SPM transducers with zero field flow, mainly because they have no magnetic deflection, while having a reduced size and cost-effective solution.

[0015] SPM transducer

[0016] Therefore, the present invention provides an SPM superparamagnetic material transducer, comprising:

[0017] - At least one SPM coil, the at least one SPM coil being formed of a core having a longitudinal axis, the core being made of SPM, and at least one electrical conductor being wound around the core along the longitudinal axis; and

[0018] - At least one feedback winding CR.

[0019] According to the present invention, the SPM transducer further includes:

[0020] - A rigid body having a longitudinal central axis and two planar surfaces at each of its opposite ends in the direction of the longitudinal central axis of the body, the planar surfaces being substantially perpendicular to the longitudinal central axis;

[0021] - At least one support channel formed in the body and accommodating the SPM coil, the support channel extending parallel to the longitudinal central axis and opening to two planar surfaces.

[0022] In addition, the feedback winding is formed by an electrical conductor that runs along the longitudinal central axis and is wound around the outer surface of the body.

[0023] Therefore, the SPM transducer of the present invention has a limited size and is formed by a rigid body configured to carry a feedback winding on its outer surface and one or more SPM coils in one or more channels formed in its inner volume.

[0024] This configuration differs from existing technologies, which typically take the form of long, flexible cables with the excitation conductor, measurement conductor, and feedback conductor wound sequentially around the SPM core.

[0025] The main body can be cylindrical. The length of the main body along the longitudinal central axis can be measured from a few centimeters to approximately ten centimeters.

[0026] Advantageously, the transducer includes several different support channels, such as two, each channel accommodating the SPM coil. The support channels extend parallel to the longitudinal central axis and are arranged within the body around the longitudinal central axis, with each channel opening at two planar surfaces of the body.

[0027] Advantageously, the two planar surfaces and the outer surface of the main body form an outer volume, in which the feedback winding is contained.

[0028] According to an embodiment, the main body is formed by a first substructure and a second hollow substructure. The first substructure includes one or more support channels, and the second hollow substructure includes two planar surfaces and an outer surface supporting the feedback coil. The first substructure is inserted into the hollow volume of the second substructure. Specifically, the first substructure is formed by a rigid support body, wherein the support channels are hollow, opening radially toward the outer surface of the main body of the first substructure, and opening at both ends of the main body of the first substructure.

[0029] Field flow sensor

[0030] The present invention also relates to a magnetic field flow sensor for measuring direct current, the magnetic field flow sensor being formed of at least one SPM superparamagnetic material transducer, the transducer being designed to be affected by an external magnetic field to be measured, the external magnetic field being induced by a current passing through a primary conductor formed of at least one electrical conductor, at least a portion of which extends along the Z-axis.

[0031] According to the present invention, the sensor includes at least:

[0032] - An SPM transducer having a longitudinal central axis X and two opposing free ends along the longitudinal central axis X, the SPM transducer being formed by a feedback winding CR coupled to at least one SPM coil extending between the two free ends;

[0033] - A magnetic circuit having at least two planar surfaces that are parallel to each other and perpendicular to the longitudinal central axis X, the two planar surfaces being positioned opposite the respective free ends of the transducer.

[0034] Furthermore, according to the invention, the sensor is designed to be positioned relative to the primary conductor such that the Z-axis is perpendicular to the longitudinal axis X and parallel to the planar surface.

[0035] In practice, the primary conductor portion is designed to allow current to pass through. The SPM transducer is formed by one or more SPM coils extending along the longitudinal axis and connected to the feedback coil. The feedback winding CR is formed by a winding of electrical conductors created around the assembly formed by the SPM coils. The primary conductor portion is located nearby, as close as possible to the SPM transducer. In practice, the primary conductor portion and the SPM transducer are preferably separated only by an electrical insulator. The two planar surfaces of the magnetic circuit are positioned opposite each other and as close as possible to the free end of the SPM transducer. Similarly, the two planar surfaces of the magnetic circuit are preferably separated from the free end of the SPM transducer only by an electrical insulator.

[0036] In practice, the magnetic circuit surrounds or encircles the assembly formed by the SPM transducer and the primary conductor to create a magnetic field flow circumference. This flow circumference is contained within a plane parallel to the longitudinal central axis X, surrounds the portion of the primary conductor, and longitudinally passes through the SPM transducer, which traverses the two planar surfaces of the magnetic circuit. Therefore, the SPM transducer acts as a field flow sensor.

[0037] According to one embodiment, the structure of the SPM transducer is similar to that of the SPM transducer described above in this invention. In fact, the two planar surfaces of the first primary circuit therefore face the two planar surfaces of the SPM transducer.

[0038] According to another embodiment, the primary conductor may include:

[0039] - The primary conductor, known as the "outward" conductor, is used to supply current I.+ Flowing along the Z-axis, which is perpendicular to the longitudinal central axis X; and

[0040] - The primary conductor, known as the "return" conductor, is used to supply current I. - Flowing in the opposite direction.

[0041] For such a primary conductor, the SPM transducer is advantageously arranged along the transverse axis Y, perpendicular to both the outward and return primary conductors. Therefore, the magnetic circuit, surrounding the outward and return primary conductors and the SPM transducer assembly, forms a path perpendicular to the current I. + and current I - The flow direction of the circumference.

[0042] According to another embodiment, the outward primary conductor and the return primary conductor can be formed by two branches of a single electrical conductor having a generally U-shaped profile. For such a primary conductor, a transducer SPM is arranged between the two branches.

[0043] According to another embodiment, the primary conductor can be a single conductor. In this case, the sensor can include two SPM transducers arranged on both sides of the single primary conductor and extending parallel to the longitudinal central axis X. Furthermore, the magnetic circuit can be in the form of two plates forming two planar surfaces, with the first plate positioned opposite the free ends of the two SPM transducers and the second plate positioned opposite the other free ends of the two SPM transducers.

[0044] According to another embodiment, for three primary conductors, the sensor may include two SPM transducers alternately positioned with the primary conductors along a transverse axis Y perpendicular to the longitudinal central axis X and axis Z, with the magnetic circuit surrounding the assembly formed by the three primary conductors and the two SPM transducers.

[0045] The sensor may also include a Hall effect sensor and / or a Rogowski coil around each primary conductor. Attached Figure Description

[0046] Other features and advantages of the invention will become clearer from the following description, with reference to the accompanying drawings, which are given by way of non-limiting example. Wherein:

[0047] Figure 1 This demonstrates the primary field H (A / m) and measurement field H of an open-loop sensor based on a known SPM material. mes The curve showing the relationship between (A / m);

[0048] Figure 2a This is a schematic diagram of an SPM transducer according to an embodiment of the present invention;

[0049] Figure 2b It is along Figure 2aCross-sectional view of the transducer's cross-sectional plane AA;

[0050] Figure 3a This is a schematic diagram of an SPM transducer according to another embodiment of the present invention;

[0051] Figure 3b It belongs to Figure 3a A schematic diagram of the main body of the SPM transducer with a support channel for the SPM coil.

[0052] Figure 4a This is a schematic diagram of a sensor according to an embodiment of the present invention;

[0053] Figure 4b yes Figure 4a A top-view cross-section of the sensor, in which the magnetic circuit is schematically shown with a rectangular outline;

[0054] Figure 5 This is a schematic diagram of a sensor according to another embodiment of the present invention;

[0055] Figure 6a This is a schematic diagram of a sensor incorporating a Rogowski coil and a Hall effect sensor according to another embodiment;

[0056] Figure 6b yes Figure 6a A top view of the sensor in the image.

[0057] Figure 7a This is a schematic diagram of a sensor according to another embodiment of the present invention, wherein the primary conductor includes a U-shaped portion;

[0058] Figure 7b yes Figure 7a A longitudinal cross-sectional view of the sensor in the image;

[0059] Figure 7c yes Figure 7a A top-view cross-section of the sensor in the image;

[0060] Figure 8a This is a schematic diagram of a sensor with a primary conductor arranged between two SPM transducers according to another embodiment of the present invention;

[0061] Figure 8b yes Figure 8a A top-view cross-section of the sensor in the image;

[0062] Figure 9a This is a schematic diagram of a sensor applicable to three primary conductors according to another embodiment of the present invention;

[0063] Figure 9b yes Figure 9a A top view of the cross-section of the sensor in the image. Detailed Implementation

[0064] An illustration of an SPM transducer according to one embodiment is shown in [illustration]. Figure 2a and Figure 2b middle.

[0065] The SPM transducer 1 is formed of a body having a longitudinal central axis X. Therefore, the body can be in the form of a solid cylinder, and the body is made of, for example, a rigid plastic material.

[0066] Therefore, the body 10 has an outer surface 100, an inner volume, and two planar surfaces 101, 102 at each of its opposite ends in the direction of its longitudinal central axis X. Both planar surfaces 101, 102 extend substantially perpendicular to the longitudinal central axis X.

[0067] Separate support channels 103 are formed within the internal volume of the body 10, in practice as a pair, for example, four support channels. Each support channel 103 is configured to accommodate the SPM coil 2. The support channels 103 extend parallel to the longitudinal central axis X around the axis X and are arranged in the body 10 in a manner that is symmetrical or asymmetrical with respect to each other, with each channel 103 opening at two planar surfaces 101, 102 of the body 10.

[0068] Therefore, the SPM coils 2 arranged in these channels 103 extend parallel to the longitudinal central axis X and also open at the two planar surfaces 101, 102 of the body. In particular, each SPM coil 2 is formed of a flexible core 20 having a longitudinal axis, the flexible core 20 being made of SPM, and at least one electrical conductor 21 is wound around the flexible core 20 along the longitudinal axis of the core 20.

[0069] The core 20 of the SPM coil 2 can have a diameter of less than or equal to 5mm. 2 The cross-section is preferably less than or equal to 1 mm. 2 The core 20 of the SPM coil 2 can have a volume concentration of less than 10% SPM material, preferably between 1% and 4%. These arrangements can reduce the use of particularly expensive SPM material.

[0070] The feedback winding 3, formed by an electrical conductor, is wound along the longitudinal central axis X on the outer surface 100 of the main body 10.

[0071] exist Figure 2a and Figure 2bIn the example shown, planar surfaces 101 and 102 can be in the form of coil flanges or disks, with a diameter larger than that of the body 10. Therefore, both planar surfaces 101 and 102, together with the outer surface 100 of the body 10, form the outer volume in which the feedback winding 3 is arranged. In other words, the transducer is in the form of a spool or tube of a cable reel, with the feedback winding axially held via a rim or flange, and the SPM coil housed within the tube.

[0072] An illustration of an SPM transducer according to another embodiment is shown in... Figure 3a and Figure 3b In this embodiment, the main body 10 is formed by a first substructure 10a and a second hollow substructure 10b. The first substructure 10a includes a support channel 103 for the SPM coil, and the second hollow substructure 10b includes two planar surfaces 101 and 102 and an outer surface 100 supporting the feedback winding. The first substructure 10a is inserted into the hollow volume of the second substructure 10b. Specifically, the first substructure 10a is formed by a rigid support body, wherein the support channel is hollow, opens radially toward the outer surface of the main body, and opens at both ends of the main body.

[0073] A magnetic field flow sensor for DC current measurement according to one embodiment is illustrated in [illustration]. Figure 4a , Figure 4b and Figure 5 The current sensor includes an SPM transducer 1, which may have a similar structure to the transducer described above and extends along the longitudinal axis X. Specifically, the SPM transducer 1 externally carries a feedback winding 3 in the form of a cylinder, and internally carries a device for measuring magnetic field flow in the form of SPM coils 2 (e.g., two pairs of SPM coils). The sensor is configured to be located around a portion of a first electrical conductor, which may be formed by a primary conductor referred to as an "outward" conductor 41 and a primary conductor referred to as a "return" conductor 42, for current I. + and current I - The current flows in opposite directions through the "outward" conductor 41 and the "return" conductor 42. Both the outward primary conductor 41 and the return primary conductor 42 extend perpendicularly to the longitudinal axis X along the Z-axis and are arranged on opposite sides of the SPM transducer along the transverse axis Y, which is perpendicular to both the X-axis and the Z-axis. The Z-axis is perpendicular to the sensor shown in the figure.

[0074] The magnetic circuit 5 surrounds the outward primary conductor 41 and the return primary conductor 42, as well as the SPM transducer 1, forming a configuration perpendicular to the current I. + and current I -The magnetic circuit 5 includes two portions or planar surfaces 51, 52 located opposite the respective free ends 101, 102 of the SPM transducer 1, which are advantageously planar surfaces as described above. The height (along the Z-axis) and length (along the Y-axis) of the planar surfaces 51, 52 of the magnetic circuit 5 are such that the planar surfaces 51, 52 at least cover the planar surfaces of the free ends of the SPM transducer. The dimensions of the planar surfaces 51, 52 may be a trade-off between the performance and volume of the magnetic material, affecting the price, size, and weight of the sensor. In practice, an electrical insulator is inserted between the various elements of the sensor, such that the magnetic circuit is preferably bonded to the electrical insulator so as close as possible to the primary conductor and the SPM transducer assembly.

[0075] Therefore, in this embodiment, the pair of outward primary conductors 41 and return primary conductors 42 are surrounded by a magnetic circuit 5 having at least two planar surfaces 51, 52 parallel to each other. An SPM transducer 1, consisting of linear SPM coils, is inserted between the outward primary conductor 41 and the return primary conductor 42, thereby creating an open measuring circumference C connecting the two planar surfaces 51, 52 of the magnetic circuit 5. In this case, the open measuring circumference C ( Figure 4b It is similar to a path that passes through both ends of the SPM transducer and extends along the X-axis.

[0076] In fact, current I is supplied to the external primary conductor 41. + =I P Through, the current may be -I during normal use. max and+I max The current I returns to the primary conductor 42 to supply current between the two. - =-I p Passing through. Feedback winding 3 supplies current I. CR It passes through and is formed by an N-turn winding around a hollow support of a conventional SPM coil 2 containing the flow rate cir for measuring the magnetic field H on the open circumference C.

[0077]

[0078] Feedback current I CR Preferably, continuous adjustment is performed to obtain a flow rate cir = 0, so that NI CR =-I p .

[0079] The SPM material is preferably a high-sensitivity SPM material, characterized by a maximum operating field H. max It is roughly smaller than the maximum field H generated by the primary conductor. pmax .

[0080] Preferably, the shape and size of the magnetic circuit and the feedback coil are adjusted so that when cir = 0 and I p =I Pmax At that time, the magnetic field fluctuation along the opening perimeter C is less than the maximum operating field H. max .

[0081] For example, the length of the opening circumference C is preferably reduced, for example, to about 50 mm. Therefore, the two planar surfaces 51 and 52 of the magnetic circuit 5 are considered to be spaced about 50 mm apart along the X-axis.

[0082] If we consider the closed perimeter C', on the one hand, it consists of the open perimeter C and the perimeter portion C connecting the two planar surfaces 51, 52 and surrounding the outward primary conductor 41 or returning to the primary conductor 42. mag The composition then leads to Ampere's theorem:

[0083]

[0084] Where H represents the magnetic field, I p This represents the current flowing in the primary conductor under consideration.

[0085] If the relative permeability μ r If the thickness of the magnetic material is sufficiently high, the second term can be ignored, so only the following can be considered:

[0086]

[0087] Furthermore, if the feedback winding around the SPM coil supplies I... CR A current of ampere revolutions passes through, therefore:

[0088]

[0089] When the flow sensor (i.e., the SPM transducer) provides a zero value, it can be said that: I CR =-I P .

[0090] Therefore, for a primary current of 500A, the feedback winding must be able to generate 500A.t, and the average fill factor of the winding must be approximately K. r =0.6. If we limit the current density to J max =5A / mm 2 Therefore, it is preferable to have a minimum winding cross-section S. Coil for:

[0091]

[0092] That is to say, the coil thickness is between 3mm and 4mm.

[0093] Such a 3mm to 4mm feedback winding is difficult to produce directly on existing SPM coils, which are typically produced on a core with a small cross-section of about 1mm.

[0094] Therefore, this invention proposes a novel configuration in which feedback is generated by means of a coil with a larger cross-section, the winding core of which is hollow and can accommodate the SPM measurement winding, such as... Figures 2a to 3b As shown.

[0095] By properly adjusting the geometric parameters of magnetic circuit 5 and feedback coil 3, any fluctuations (one or more) of the magnetic field along the opening perimeter C can be reduced.

[0096] The magnetic circuit material is preferably made of a material with high magnetic permeability and low coercivity (e.g., based on 80% FeNi). In fact, the absence of any magnetic deflection in the SPM coil does not mean that the device is also free of magnetic deflection. The SPM core material is characterized by its coercivity H... C And in the absence of current, we have:

[0097]

[0098] The field inside the material is between +H C and -H C Therefore, it can be stated as follows:

[0099]

[0100] Among them, l mag It is the length of magnetic circuit 5, which can close the circumference C.

[0101] Therefore, the resulting current I0 may be affected by I0 <H c l mag Restrictions.

[0102] Therefore, to reduce I0, materials with low coercivity can be selected, such as H. c FeNi type alloy with 80% Ni and a strength of 0.6 A / m.

[0103] In addition, in order to reduce l mag One solution involves, when these conductors have a rectangular cross-section, such as Figure 5 The outward and return primary conductors are oriented. In this way, magnetic circuit 5 becomes more compact.

[0104] In some applications, it may be advantageous to be able to measure overload currents greater than the maximum current that the feedback current can compensate for, especially for protection purposes. Therefore, such as... Figure 6a and Figure 6bAs shown, a Hall effect sensor 6 can be arranged between the two primary conductors 41, 42. This Hall effect sensor 6 will be advantageously supported by a printed circuit 7 configured to connect to an SPM transducer.

[0105] Finally, the short-circuit current can be measured using a device of the type of Rogowski coil or winding 8. Therefore, it is advantageous that the sensor can integrate one or more Rogowski coils 8, each placed around one of the primary conductors 41, 42. These Rogowski coils 8 can advantageously be integrated into a printed circuit 8. For example, Rogowski coils in the form of printed circuits described in document EP3268754 and / or Hall effect sensors described in document FR2947060 can be implemented in the sensor of the present invention, but these examples are not limiting, as any type of commercially available sensor may be suitable.

[0106] according to Figures 7a to 7c In another embodiment shown, the primary outward conductor 41 and the return conductor 42 can be formed by two branches of a single electrical conductor 40 having a generally U-shaped profile. An SPM transducer 1 is arranged between the two branches of the U-shape, and a magnetic circuit 5 surrounds the two branches. Therefore, two flow curves C1' and C2' can be identified for measurement purposes. The first flow curve C1' of the field flow around the branch 41 of the primary conductor consists of an open flow curve C and an open flow curve C2'. mag1 Formation. The measuring circumferential line C passes along the SPM transducer 1 and connects the two planar surfaces 51 and 52 of the magnetic circuit 5. Circumferential line C mag1 The magnetic circuit flows through the branch connecting the two planar surfaces 51 and 52 and around the primary conductor. The second circumference C2' of the field flow around the other branch 42 of the primary conductor is formed by the open circumference C and the second open circumference C flowing through the other part of the magnetic circuit 5 connecting the two planar surfaces 51 and 52 and around the other branch of the primary conductor. mag2 form.

[0107] according to Figure 8a and Figure 8b In another embodiment shown, the primary conductor is formed by a single conductor 43 arranged between two SPM transducers 1A and 1B. SPM transducers 1A and 1B are substantially identical. The magnetic route is formed by two plates 54 and 55, creating two planar surfaces. The first plate 54 is located opposite one free end of the two SPM transducers 1A and 1B, while the second plate 55 is located opposite the other free end of the two SPM transducers 1A and 1B. Figure 8b As shown, the measuring curve C' is formed by curves C1A and C1B flowing along the corresponding SPM transducers 1A and 1B, and curves Cmag54 and Cmag55 flowing in the corresponding plates 54 and 55. Therefore, curve C' is a closed curve around the primary conductor 43.

[0108] In some types of DC current applications, the number of primary conductors can be three: a first primary conductor P0, specifically used as a reference (0 volts), a second primary conductor P... + Used to supply current I + Passing through, and the third primary conductor P - Used to supply current I - Through, current I - Direction and current I + On the contrary, in reality, the current I + and I - They may not have the same amplitude, which means that a current I0 may exist in the first primary reference conductor. Therefore, in the absence of leakage current, I0+I + +I - =0.

[0109] Figure 9a and Figure 9b The configuration shown solves this problem based on the same principle as the aforementioned embodiments. Therefore, three primary conductors 44, 45, and 46 are arranged alternately with two SPM transducers 1A and 1B, and a magnetic circuit 5 surrounds the assembly. Thus, each SPM transducer 1A and 1B is arranged between two primary conductors 44, 45, and 46 and extends parallel to axis X. Furthermore, as in the aforementioned embodiments, the magnetic circuit 5 ( Figure 9a (Drawn in dashed lines) includes two planar surfaces 51 and 52 located opposite the two free ends of the SPM transducer to form different circumferences.

[0110] The first primary conductor 44 can be used to supply current I + Conductor P passing through + The second conductor 45 can be a reference conductor P0, and the third conductor 46 can be used to supply current I. - The conductor P- passes through.

[0111] If the flow sensor (i.e., SPM transducer 1A) is placed on conductor P + Between P0 and P0, the field flow rate is measured along the path formed by the circumferential line C+', which is formed by the path C along the SPM transducer 1A. + and through the left side of magnetic circuit 5 to surround conductor P + Path C mag+ This, in the absence of any feedback current, results in:

[0112]

[0113] Since the flux in the material of the magnetic circuit can be considered negligible, therefore in path C +The flow rate measured is approximately equal to I+. When the same number of amperes per revolution is applied in the feedback, zero flow is obtained. The same reasoning applies to the flow rates placed on conductors P0 and P1. - SPM transducer 1B between.

[0114] This invention is obviously not limited to the exemplary embodiments described, but covers any modifications and variations within the scope of the appended claims that will be obvious to those skilled in the art. Furthermore, the technical features of the various embodiments and variations mentioned above can be combined in whole or in part.

Claims

1. A magnetic field flow sensor for measuring direct current, the magnetic field flow sensor comprising at least one SPM superparamagnetic material transducer, the transducer being designed to be influenced by an external magnetic field to be measured, the external magnetic field being induced by a current passing through a primary conductor (40-46) formed of at least one electrical conductor, at least a portion of said at least one electrical conductor extending along the Z-axis (Z), characterized in that, The sensor includes at least: -SPM superparamagnetic material SPM transducer (1), the transducer includes: At least one SPM coil (2), said at least one SPM coil being formed of a core (20) having a longitudinal axis, said core (20) being made of SPM, and said core (20) having at least one electrical conductor wound around said core (20) along said longitudinal axis; and At least one feedback winding (3); A rigid body (10) having a longitudinal central axis (X) and two planar surfaces (101, 102) at each of the opposite ends of the body (10) in the direction of the longitudinal central axis (X), the two planar surfaces (101, 102) being substantially perpendicular to the longitudinal central axis (X); At least one support channel (103) is formed in the body (10) and accommodates the SPM coil (2). The support channel (103) extends parallel to the longitudinal central axis (X) and opens to two planar surfaces (101, 102). The feedback winding (3) is formed by an electrical conductor that is wound along the longitudinal central axis (X) and around the outer surface of the body (10); The SPM transducer (1) has two opposing free ends along the longitudinal central axis (X), and the SPM transducer (1) is formed by the feedback winding (3) coupled to the at least one SPM coil (2) extending between the two free ends. And wherein the sensor includes: - Magnetic circuit (5), the magnetic circuit (5) having at least two parts (51, 52) that are parallel to each other and perpendicular to the longitudinal central axis (X), the two parts (51, 52) being positioned opposite to the corresponding free ends of the SPM transducer (1); Furthermore, the sensor is positioned relative to the primary conductor (40-46) such that the Z-axis (Z) is perpendicular to the longitudinal central axis (X) and parallel to the two portions (51, 52).

2. The magnetic field flow sensor according to claim 1, characterized in that, The transducer also includes several different support channels (103), each channel (103) accommodating an SPM coil (2), the support channels (103) extending parallel to the longitudinal central axis (X) and arranged around the longitudinal central axis (X) within the body (10), each channel (103) opening at two planar surfaces (101, 102) of the body.

3. The magnetic field flow sensor according to any one of claims 1 to 2, characterized in that, The core (20) of the at least one SPM coil (2) has a diameter of less than or equal to 5 mm. 2 The cross-section has a volume concentration of less than 10% SPM material.

4. The magnetic field flow sensor according to any one of claims 1 to 2, characterized in that, Two planar surfaces (101, 102) form an outer volume with the outer surface (100) of the main body (10), and the feedback winding (3) is contained in the outer volume.

5. The magnetic field flow sensor according to any one of claims 1 to 2, characterized in that, The main body (10) is formed by a first substructure (10a) and a second hollow substructure (10b). The first substructure (10a) includes at least one support channel (103), and the second hollow substructure (10b) includes two planar surfaces (101, 102) and an outer surface (100) supporting the feedback winding (3). The first substructure (10a) is inserted into the hollow volume of the second hollow substructure (10b). The at least one support channel (103) opens radially toward the outer surface of the main body of the first substructure (10a) and opens at both ends of the main body of the first substructure (10a).

6. The magnetic field flow sensor according to any one of claims 1 to 2, characterized in that, For primary conductors, including: - A primary conductor, referred to as the "outward" conductor (41), is used to allow current to flow along the Z-axis (Z) direction; and - The primary conductor, known as the "return" conductor (42), is used to allow current to flow in the opposite direction; The SPM transducer (1) is arranged along a transverse axis (Y) perpendicular to the longitudinal central axis (X) and the Z axis (Z) between the primary outward conductor (41) and the return conductor (42). The magnetic circuit (5) surrounds the primary outward conductor (41), the return conductor (42) and the SPM transducer (1) to form a field flow circumference perpendicular to the direction of current flow.

7. The magnetic field flow sensor according to claim 6, characterized in that, The SPM transducer (1) is arranged between the two branches, which are formed by two branches of a single electrical conductor with a generally U-shaped profile, forming an outward primary conductor (41) and a return primary conductor (42).

8. The magnetic field flow sensor according to any one of claims 1 to 2, characterized in that, For a single primary conductor (43), two SPM transducers (1A, 1B) are arranged on both sides of the primary conductor (43) and extend parallel to the longitudinal central axis (X), and the magnetic circuit (5) includes two plates (54, 55) forming two parts (51, 52), one plate (54) being positioned opposite the free ends of the two SPM transducers (1A, 1B), and the other plate (55) being positioned opposite the other free ends of the two SPM transducers (1A, 1B).

9. The magnetic field flow sensor according to any one of claims 1 to 2, characterized in that, For the three primary conductors (44, 45, 46), the sensor includes two SPM transducers (1A, 1B) alternately positioned with the primary conductors (44, 45, 46) along a transverse axis (Y) perpendicular to the longitudinal central axis (X) and the Z axis (Z), and the magnetic circuit (5) surrounds the assembly formed by the three primary conductors (44, 45, 46) and the two SPM transducers (1A, 1B).

10. The magnetic field flow sensor according to any one of claims 1 to 2, characterized in that, The sensor also includes a Hall effect sensor (7) and / or a Rogowski coil (9) around each primary conductor.

Images