• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    An apparatus for measuring a magnetic field comprises four cores (1-4) with cores (1N-4N) of superparamagnetic material, and injection means in the coils of a direct current and of two alternating currents which have different frequencies. . The value of the magnetic field is deduced from the value of the DC current which is necessary to cancel a component amplitude at a mixing frequency. A structure of the electrical connections to the coils reduces disturbances by the alternating currents that are used on the detection of the component at the mixing frequency. Particular configurations for the coils further reduce the influence of spurious electromagnetic radiation on the measurement results. The device can also be used to measure DC currents.
    公开号:FR3038063A1
    申请号:FR1555928
    申请日:2015-06-26
    公开日:2016-12-30
    发明作者:Thierry Augais
    申请人:Atware；
    IPC主号:
    专利说明:

    [0001] The present invention relates to an apparatus for measuring a magnetic field, as well as methods that use such an apparatus for measuring a magnetic field or a direct current. Many applications require measuring a magnetic field, either because the value of the magnetic field is sought by itself, or because it gives access to the value of another physical quantity that is sought. In particular, it is known that the value of a direct current can be deduced from a measurement of the magnetic field that is generated by this direct current.
    [0002] However, there is still a great need for improved magnetic field measuring devices, in particular on the following criteria: the device enables accurate and reliable measurements; - the device can be manufactured at reduced cost; - the device causes energy consumption that is low to achieve each measurement; the results of the measurements that are made with the apparatus are not affected, or are little affected, by involuntary offsets of signals, called offsets; the measurements which are carried out with the apparatus have a signal-to-noise ratio which is high; the device produces measurement results that are robust with respect to external electromagnetic disturbances; and - the device must meet the regulatory requirements for electromagnetic compatibility (EMC compatibility). To improve these criteria over existing devices, a first aspect of the present invention provides a novel apparatus for measuring a magnetic field, which comprises: - four superparamagnetic core electrical wire coils, the four core coils having electrical and electromagnetic geometries and properties which are identical or substantially identical, and the four coils being electrically connected in series so as to form a chain with two end terminals of the chain, a center terminal in the chain, and two secondary terminals of the chain which are each located between the central terminal and one of the two extreme terminals; Means for injecting a direct current into the coil chain, which are connected to the two end terminals of the coil chain, and means for adjusting a direct current intensity; means for injecting a first alternating current having a first frequency, which are connected to inject the first alternating current into the coil chain via the central terminal, and to take up this first alternating current through the two end terminals, whereby the first alternating current flows with first intensities which are identical or substantially identical by the two extreme terminals without flowing through the secondary terminals; means for injecting a second alternating current having a second frequency different from the first frequency, these means for injecting the second alternating current being connected to inject the second alternating current into the coil chain via the two secondary terminals; , and to take the second alternating current by the central terminal and the two end terminals so that the second alternating current flows with second intensities which are identical or substantially identical by the two secondary terminals, and that flows with third intensities which are identical or substantially identical in all the coils but in opposite directions between two coils which are successive in the chain; and means for detecting at least one voltage component that exists between the two secondary terminals of the coil chain, a frequency of this electrical voltage component, called the mixing frequency, being a linear combination of the first frequency and the second frequency, with linear combination coefficients that are fixed, integer and non-zero. The apparatus of the invention is adapted to adjust the intensity of the DC current so as to cancel an amplitude of the voltage component which has the mixing frequency. Thus, when the four coils are placed in the magnetic field, a value of the DC current which cancels the magnitude of the voltage component having the mixing frequency, is proportional to an intensity of the magnetic field. In the context of the invention, superparamagnetic material is understood to mean a non-linear magnetic material which exhibits no hysteresis when the magnetic excitation, or magnetic field, which is applied to this material is varied periodically.
    [0003] In the apparatus of the invention, the superparamagnetic material of the cores is used as a developer of a total permanent magnetic field which is not zero inside the coils. This total permanent magnetic field is the sum of the magnetic field to be measured, which is assumed to be permanent, or static, and a compensating magnetic field that is produced by the DC current injected into the coils. However, the superparamagnetic material exhibits a non-linear behavior with respect to the first and second alternating currents as soon as the total permanent magnetic field is not zero, whereas this behavior becomes substantially linear if the total permanent magnetic field is zero. With this, the nullity of the total permanent magnetic field is detected by the detection means, through the nullity of the voltage component at the mixing frequency. By knowing the relation between the DC current which is injected into the coils and the compensation magnetic field produced by this direct current, by calibration or by calculation, the value of this direct current which produces the cancellation of the voltage component at the mixing frequency provides a value for the magnetic field to be measured. In other words, the apparatus of the invention uses a compensation measurement principle, for which the nullity of the voltage component at the mixing frequency constitutes an exact compensation indicator. Such an apparatus can be manufactured using electrical components that are commercially available at low cost, especially because they are already produced in large batches for other applications. The connection of the direct current injection means to the coils, those of the injection means of the first and second alternating currents, as well as the connection of the detection means, reduce or eliminate by their connection directions contributions in the signal which is transmitted to the detection means that would be due to the first and second alternating currents. The detection of the voltage component at the mixing frequency is then more accurate and more reliable. In addition, the current injection means can be selected or designed easily to ensure electromagnetic compatibility.
    [0004] Furthermore, a quotient between the first and second frequencies may preferably be greater than 10, so that the means for detecting the voltage component at the mixing frequency isolate this component with a higher efficiency. In preferred embodiments of an apparatus according to the invention, the direct current injection means, the first alternating current injection means and the second alternating current injection means may together comprise four connection cables. which are dedicated respectively to each of the four coils. Each of the cables comprises two electrical wires which are connected one-to-one to the two successive terminals in the chain of coils which directly connect the coil to which this cable is dedicated. Thus, all the DC current, all the first AC current and all the second AC current that are injected into the coils are transported back and forth through the four cables. Then, respective lengths of the four cables can be adjusted so that the third intensities of the second alternating current are identical or substantially identical in absolute value in all the coils of the chain. In addition, the transfer of electrical energy to the coils from the AC injection means having the highest frequency can be improved in this way. The energy consumption of the device, for an identical measurement sensitivity, can thus be reduced. On the other hand, when the second frequency is greater than the first frequency, the second alternating current injection means may comprise a source of the second alternating current and a primary winding of a transformer, with a current output of the source which is connected to a midpoint of the primary winding of the transformer. The two end terminals of the primary winding are then connected respectively to the two secondary terminals of the coil chain, and a secondary winding of the transformer belongs to the voltage voltage component detecting means which has the mixing frequency. In such an embodiment, the voltage which is transmitted to the detection means has, by design of the apparatus, components at the first and second frequencies which have zero amplitudes. For this reason, the apparatus of the invention may be said to be self-compensated with respect to possible contributions of the excitation signals at the first and second frequencies in the signal that is detected. The mixing frequency component can thus be isolated with higher efficiency and purity. In particular, in order to obtain a higher signal-to-noise ratio, the means for detecting the voltage component which has the mixing frequency in an apparatus according to the invention may comprise: a first synchronous demodulator which is coupled to the injection means of the second alternating current, and which is arranged to frequency shift the voltage component which has the mixing frequency, by suppressing a contribution of the second frequency in this frequency mixture ; and a second synchronous demodulator which is coupled to the injection means of the first alternating current, and which is arranged to frequency shift the voltage component which has the mixing frequency, by suppressing a contribution of the first frequency in this mixing frequency. These first and second synchronous demodulators are then cascaded to output a continuous electrical signal which is proportional to an amplitude of the voltage component that has the mixing frequency. This signal constitutes the detection signal, after possible amplification. In addition, when the second frequency is greater than the first frequency, the second alternating current injection means may comprise means for multiplying an instantaneous intensity of the second alternating current by a pseudo-random sequence of factors each equal to +1. or -1, so as to create a modulation of the second alternating current which is also suppressed by the first synchronous demodulator. The signal-to-noise ratio of the device can be further increased in this way.
    [0005] Optionally, to further increase the sensitivity of the detection means, these can be adapted to detect an association of two components of the alternating voltage that exists between the two secondary terminals of the coil chain, corresponding to two distinct mixing frequencies. . However, in such a case, these two components have opposing contributions for the lowest between the first and the second frequencies in the linear combinations that constitute the two mixing frequencies, and contributions that are identical for the highest. between the first and the second frequency. In general, when the second frequency is greater than the first frequency, the first alternating current injection means can be connected to the central terminal of the coil chain by a first capacitor which is adapted to be an AC conductor 3038063 At the first frequency and the second frequency. Simultaneously, the second alternating current injection means may be connected to each of the two secondary terminals of the coil chain by a respective second capacitor which is adapted to conduct AC current at the second frequency but not at the first frequency. . Such an embodiment of the apparatus contributes to the distribution in the four coils which is desired for the direct current, the first alternating current and the second alternating current. The arrangement of the four coils relative to one another, as well as their respective winding directions for the electrical wire, can be advantageously adapted to the geometry and symmetries of the magnetic field to be measured. Thus, the sensitivity of the apparatus to the magnetic field to be measured can be improved, while its sensitivity to stray magnetic fields unrelated to the magnetic field to be measured can be decreased. A second aspect of the invention provides a method for measuring a magnetic field, which comprises the following steps: placing the four coils of an apparatus which is in accordance with the first aspect of the invention in a magnetic field; and 20/2 / adjusting the intensity of the DC current that is produced by the DC injection means so as to cancel the amplitude of the voltage component that has the mixing frequency. Then, the value of the DC current that is produced by the DC injection means and which has been adjusted to step / 2 / is a measurement result for the magnetic field. A third aspect of the invention provides a method for measuring a continuous electric current, which comprises the steps of: providing a device that is in accordance with the first aspect of the invention; 30/2 / arranging the four coils near the continuous electrical current to be measured, called the unknown current, or around this unknown current so that this unknown current passes through the loops of the four cores at the same time. outside the coils; and / 3 / adjusting the intensity of the DC current that is produced by the DC injection means in the coil chain so as to cancel the amplitude of the voltage component which has the mixing frequency. Then, the value of the intensity of the direct current which is produced by the DC injection means and which has been adjusted to step / 3 /, constitutes a measurement result for the unknown current.
    [0006] Other features and advantages of the present invention will appear in the following description of nonlimiting exemplary embodiments, with reference to the appended drawings, in which: FIGS. 1a, 1b and 1c are views in perspective of three possible configurations for the four coils of an apparatus according to the invention; FIG. 2 is a block diagram of an apparatus according to the invention; and FIG. 3 corresponds to FIG. 2 for particular embodiments of the current injection means.
    [0007] For the sake of clarity of Figs. 1c-1c, the apparent dimensions of the elements shown therein correspond neither to actual dimensions nor to actual dimension ratios. In addition, identical references which are indicated in different figures designate identical elements or which have identical functions.
    [0008] In FIGS. 1a-1c, references 1 to 4 denote four coils of electrical wire which are designed to be identical. References 1N to 4N denote four superparamagnetic material cores which are designed to be identical, and are each placed in one of coils 1 to 4, in the same way for all coils.
    [0009] Coils 1 to 4 are electrically connected in series. A and B respectively denote the extreme terminals of the series connection of the coils 1-4, the terminal A being on the coil 1 side and the B terminal on the coil side 4. S1 and S2, so-called terminals. secondary, are respectively intermediate between the coils 1 and 2, and between the coils 3 and 4, and C, said central terminal, is intermediate between the coils 2 and 3.
    [0010] In the configuration of Figure 1a, the four coils 1-4 are all parallel to a common axis, which is vertical in the figure. They are juxtaposed with each other and have respective winding directions of the electrical wire around the cores N1-N4 which are identical with respect to the common axis. This first configuration is adapted to measure a magnetic field that is substantially uniform in the space portion that is occupied by the four core coils. The magnetic field to be measured is noted Field B in Figure 1a. For its measurement, all four core coils must be brought into the area of the magnetic field and oriented so that the common axis of the coils 1-4 and N1-N4 cores is parallel to the magnetic field to be measured. In the configuration of Figure 1b, the four coils 1-4 are still all parallel to a common axis, which is vertical in the figure. But they are divided into two pairs of coils, with the coils of the same pair which have winding directions of the electrical wire around the cores which are identical for the two coils of this pair, and inverse in the winding direction. coils of the other pair. In addition, the coils of the same pair are juxtaposed while the two pairs of coils are spaced from each other perpendicular to the common axis. In Fig. 1b, coils 1 and 2 together constitute the first pair, and coils 3 and 4 together constitute the second pair. d is the separation distance between the two pairs. This second configuration is adapted to measure a magnetic field which is inverted, but equal in modulus, between the location of the first pair and that of the second pair. It is adapted in particular to measure the magnetic field produced by an electric current denoted I, whose trajectory is rectilinear and centered between the two pairs of coils, perpendicular to the common axis of the coils and also to the separation direction two pairs of coils. The ellipses which are drawn in FIG. 1b are field lines of the magnetic field B which is created by the current I. These field lines are circles in space whose axis is the trajectory of the current I. , and appear as ellipses in the perspective view. Such a configuration makes it possible to compensate between the two pairs of coils for parasitic electrical voltages which are induced by external electromagnetic radiation. Obviously, the configuration of FIG. 1b can be modified by equivalence by sliding one of the pairs along the lines of the magnetic field, so that the coils of this pair remain parallel to the field lines at the location of the pair. In the configuration of FIG. 1c, each core 1N-4N is in the form of a closed loop and each coil 1-4 is wound on the core of this coil perpendicular to a longitudinal direction of the loop. In addition, the four core coils are juxtaposed to each other over a full loop length of the cores, and have winding directions of the electrical wire that are identical. This third configuration is adapted to measure magnetic fields that have distributions similar to that just described with reference to Figure 1b. In particular, it is adapted to measure the magnetic field that is created by a current I whose trajectory is superimposed on the axis of the loops which are constituted by the cores. This third configuration ensures that external electromagnetic radiation has almost no influence on the measurement results provided by the apparatus of the invention. The designations which have been used in the general part of the present description have the following correspondences with those of the embodiment of FIGS. 2 and 3: the first frequency may be equal to 1 kHz for example and is denoted BF, and the second frequency can be equal to 200 kHz and is denoted HF. These values for the frequencies BF and HF make it possible to use filters which are commercially available, in particular for radio applications. The first and second alternating currents, which respectively have the frequencies BF and HF, are denoted IBF and IHF. DC current is noted IDc. The following references which are indicated in FIG. 2 have the meanings given below: DC generator Inc, referred to as DC injection means; 6 IBF current generator, called injection means of the first alternating current; IHF current generator, called injection means of the second alternating current; 8 transformer, with a primary winding referenced 73 and a secondary winding referenced 91; Means for detecting an AC voltage component which exists between the secondary terminals S1 and S2, with a mixing frequency which is a linear combination of the frequencies BF and HF; 10 means for measuring the direct current; 11 electrical resistances equal to each other, denoted SHUNT; Means for measuring the voltage across the electrical resistor 5, such as a continuous voltmeter denoted VDC; C1 capacitor sized to transmit the current IBF, and which therefore also transmits a current at the frequency HF; and C2 capacitors sized to transmit currents at the RF frequency, but to prevent current flows at the frequency BF. The generator 5 can be formed of a DC voltage source 51, a variable DC-DC converter 52 and a filter 53. VDD is the DC voltage that is produced by the source 51. The converter 52 can be Controlled by an operator to adjust the value of the intensity of the current Inc. The filter 53 ensures that currents at the frequencies BF and HF can flow out of the coils 1-4 by the end terminal A. The generator 5 therefore produces the current Ipc with an intensity value that is adjustable at will.
    [0011] The resistor 11 and the voltmeter 12 together constitute the means 3038063 for measuring the intensity lac. These means 10 are advantageously interposed in series between the output of the generator 5 and the terminal A of the chain of the coils 1-4. The two resistors 11 arranged symmetrically at terminals A and B ensure that the alternating currents are balanced in the four coils 1-4. The generator 6 may be formed of an alternating current source at the frequency BF, referenced 61, and optionally a modulator 62, denoted MOD. LF. When used, the modulator 62 is connected in series with the output of the source 61. CTRL BF designates a control signal or a source signal of the generator 6. The output of the source 61, or of the modulator 62, is connected to the central terminal C via the capacitor C1. The capacitor 63 ensures that a current at the RF frequency can flow out of the coils 1-4 by the terminal C. The generator 6 produces the current IBF. The generator 7 may be formed of an alternating current source at the frequency HF, referenced 71, optionally a modulator 72, denoted MOD. HF, and the primary winding 73 of the transformer 8. When used, the modulator 72 is connected in series to the output of the source 71. CTRL HF designates a control signal or a source signal of the generator 7. The output of the source 71, or the modulator 72, is connected to a midpoint J of the primary winding 73 of the transformer 8. The end terminals F and H of the primary winding 73 are connected to the secondary terminals S1 and S2 of the chain of coils 1-4, respectively, via capacitors C2. Generator 7 produces the HF current. Thanks to these connections, the four coils 1-4 are each traversed by the direct current lac, by a part of the intensity of the current IBF and also by a part 13 of the intensity of the current 1HF, with the currents orientations. which are indicated in the right-hand part of FIG. 2. In addition, the portions of intensities and 13 of the two alternating currents are: = IBF / 2 and 13 = IHF / 4. In addition, the 1HF current is injected into the coil chain 1-4 with an intensity of 12 = IHF / 2 by each of the secondary terminals S1 and S2. The detection means 9 comprise the secondary winding 91 of the transformer 8, an amplifier 92, denoted AMPLI, a first synchronous demodulator 93, denoted DEMOD. 1, and a second synchronous demodulator 94, denoted DEMOD. 2. The synchronous demodulator 93 receives as input the voltage that exists across the secondary winding 91, after amplification of this voltage, and simultaneously receives the signal CTRL HF which is introduced into the generator 7. It is adapted to perform a frequency transfer on the component of the voltage in the secondary winding 91 which has the frequency HF-BF, and also advantageously on the component of the same voltage which has the frequency HF + BF. Preferably, the synchronous demodulator 93 may be of analog type. When the modulator 72 is used, the modulation of the IHF current that is produced by this modulator 72 is automatically taken into account by the synchronous demodulator 93. For example, this modulation of the IHF current may consist in reversing the direction of the IHF current repeatedly. in a random or pseudo-random time sequence. Such inversions of current return to multiply the current IHF by successive factors each equal to +1 or -1, for varying periods of time, and produce a spectral spread of the current IHF such that this current is delivered by the generator 7. Advantageously, the signal which is outputted by the synchronous demodulator 93 can be amplified before being introduced into the synchronous demodulator 94. The synchronous demodulator 94 thus receives as input the signal which is produced by the synchronous demodulator 93, after possible amplification, and simultaneously receives the signal CTRL BF which is introduced into the generator 6. It is adapted to perform a frequency transfer on the signal which is produced by the synchronous demodulator 93. Preferably, the synchronous demodulator 94 may be of digital type. When the modulator 62 is used, the modulation of the current IBF which is produced by this modulator 62 is automatically taken into account by the synchronous demodulator 94.
    [0012] In this way, the detecting means 9 outputs a DC voltage which is proportional to the magnitude of the HF-BF component contained in the voltage between the secondary terminals S1 and S2. . This component at the frequency HF-BF results from the non-linear behavior of the superparamagnetic material of the sample 100. Due to this nonlinear behavior, the response of the superparamagnetic material of the nuclei 1N-4N to the simultaneous excitations according to the two frequencies HF and BF contain signals at frequencies that are linear combinations of the two frequencies HF and BF, with linear combination coefficients that are integers. In the present case, the synchronous demodulators 93 and 94 select that of these combinations which is the difference HF-BF. The amplitude of the component at this HF-BF frequency constitutes the detection signal, and can be evaluated by a voltmeter. FIG. 3 illustrates possible embodiments for the generators 5-7 which are particularly economical, and a way of connecting them to the coils 1-4 which makes it possible to improve the energy transfer of the generators 5-7 to the coils 1- 4.
    [0013] The DC generator 5 can be formed by two generators 5a and 5b which are identical but respectively connected to the terminals A and B so as to be able to inject the direct current IDc into the coil chain of the terminal A to the terminal B or in the opposite direction. Only one of the two generators 5a and 5b is therefore activated for each measurement, depending on the sign that is desired for the current C. Each generator 5a, 5b comprises two switches which are connected in series between the two terminals (VDD and ground) of the source 51. Such an assembly, designated by the reference 54, is commonly called "bridge arm" in the language of the skilled person. It is intended for a hash function. The intermediate terminal between the two switches of each generator 5a, 5b is connected to the output of this generator via the filter 53. The control of the switches by pulse width modulation, or PWM for "pulse width modulation" in English, adjusts the absolute value of the intensity of the direct current IDc. The means 10 for measuring the current IDc are advantageously interposed in series between the output of the generator 5a and the terminal A of the chain of the coils 1-4, and the other resistor 11 can be interposed in series between the output of the generator 5b. and terminal B of the chain of coils 1-4. The alternating current generator 6 can also be made from a bridge arm, referenced 64, and a matched filter 65. The bridge arm of the generator 6 can also be powered by the source 51, and its two switches are alternately controlled at the frequency BF. The filter 65, denoted by the filter BF, selects the fundamental component for transmission at the output to the central terminal C. Finally, the alternating current generator 7 can still be produced from a bridge arm, referenced 74, and from A matched filter 75. The bridge arm of the generator 7 can be powered similarly by the source 51, and its two switches are alternately controlled at the RF frequency. The filter 75 selects a spectral interval around the fundamental component for transmission at the secondary terminals Si and S2. In known manner, such a constitution of the generator 7 makes it possible to simply perform the spectral spreading modulation, by shifting the control pulses of the bridge arm by a half-period in a random time sequence. The outputs of the generators 5a, 5b and 6 and the two end terminals F and H of the primary winding 73 of the transformer 8, can be connected to the terminals A, B, C and 51, S2 by four two-wire cables CC1-CC4. The four CC1-CC4 cables are advantageously of the same type, two-wire or coaxial, preferably shielded and with characteristic impedance controlled. They are connected in the following way: the first wire of the cable CC1 connects the output of the generator 5a to the terminal A of the chain of the coils 1-4; the second wire of the cable CC1 and the first wire of the cable CC2 are connected in parallel to connect the extreme terminal F of the primary winding of the transformer 8 to the secondary terminal Si of the chain of the coils 14, via the first capacitor C2; the second wire of the cable CC2 and the first wire of the cable CC3 are connected in parallel to connect the output G of the generator 6 to the central terminal 30C of the chain of the coils 1-4, via the capacitor C1; the second wire of the cable CC3 and the first wire of the cable CC4 are connected in parallel to connect the extreme terminal H of the primary winding of the transformer 8 to the secondary terminal S2 of the chain of the coils 1-4, via the second capacitor C2; and the second wire of the cable CC4 connects the output of the generator 5b to the terminal B 5 of the chain of the coils 1-4. Then, the respective lengths of the CC1-CC4 cables can be selected advantageously to adjust the connection impedances that are effective for the IHF alternating current. Thus, it is possible to increase the electrical energy that is transferred by the generator 7 to the coils 1-4, at equivalent power consumption of the apparatus. An apparatus according to the invention which for example has the configuration of the coils of FIG. 1a, can be used in the following way to measure the magnetic field B. The set of four coils 1-4 is placed in the magnetic field to measure, preferably with the common axis 15 of the coils which is parallel to the magnetic field. In the absence of direct current IDc (Ipc = 0), the two alternating currents IBF and IHF generate a detection signal which is non-zero at the output of the synchronous modulator 94. The intensity of the direct current IDc is then adjusted by means of of the variable converter 52 to cancel this detection signal. Optionally, this adjustment may be automated by slaving a command from the converter 52 to the output of the synchronous demodulator 94. The value of the DC current IDc which produces the cancellation of the detection signal is the measurement result of the magnetic field. It may optionally be converted to a magnetic field unit by knowing a numerical relationship between the magnitude of the magnetic field of compensation that is produced by the coils 1-4 and the intensity of the DC current. However, an apparatus which is in accordance with FIG. The invention can also be used to measure a DC current I which is unknown. The unknown current I is then measured by means of the magnetic field that it generates. This magnetic field is measured in the manner just described, and the value of the unknown current is deduced from the value that has been measured for the magnetic field, knowing the trajectory of the unknown current I and the positions of the current. - Coils 1-4 with respect to this trajectory. Those skilled in the art, particularly competent in magnetostatics, know how to relate the value measured for the magnetic field to the value of the intensity of the unknown current I. Advantageously, the coils 1-4 are arranged relative to the path of the unknown current I. In a way that is adapted to the shape of the magnetic field lines, and to have a simple numerical relationship between the value of the unknown current I and that of the measured magnetic field. The configurations of Figures 1b and 1c are particularly suitable for this. It is to be understood that the invention may be reproduced by modifying secondary aspects thereof in relation to the detailed description which has been given above, while retaining at least some of the advantages mentioned. Among these modifications, mention may be made in a nonlimiting manner: the positions and relative orientations of the four coils 1-4 can be changed; The use of the modulators 62 and 72 can be combined with the production of the generators 6 and 7 from bridge arms; the generators 5, 6 and 7 may have constitutions different from those described with reference to FIGS. 2 and 3; and - the frequency mixture which is selected by the detecting means 9 to obtain the measurement signal, can be a linear combination of the frequencies BF and HF other than the difference HF-BF and the sum HF + BF.
    权利要求:
    Claims (11)
    [0001]
    CLAIMS1 Apparatus for measuring a magnetic field, comprising: - four coils (1-4) of non-linear magnetic core wire without hysteresis, called superparamagnetic cores (1N-4N), the four core coils having geometries and properties electrically and electromagnetically which are identical or substantially identical, and being electrically connected in series so as to form a chain with two end terminals (A, B) of said chain, a center terminal (C) in said chain, and two secondary terminals ( Si, S2) of said chain which are each located between the central terminal and one of the two end terminals; means (5) for injecting a direct current (Ipc) into the coil chain, connected to the two end terminals (A, B) of the coil chain (1-4), and adjustment means a direct current intensity; means (6) for injecting a first alternating current (IBF) having a first frequency (BF), connected to inject said first alternating current into the coil chain (1-4) via the central terminal (C) , and to take back said first alternating current through the two extreme terminals (A, B), so that the first alternating current flows with first intensities which are identical or substantially identical by said two extreme terminals without flowing through them. secondary terminals (51, S2); means (7) for injecting a second alternating current (IHF) having a second frequency (HF) different from the first frequency (BF), connected to inject said second alternating current into the coil chain (1-4 ) by the two secondary terminals (Si, S2), and to take back said second alternating current by the central terminal (C) and the two end terminals (A, B) so that the second alternating current flows with second intensities which are identical or substantially identical by said two secondary terminals, and so that said second alternating current flows with third intensities which are identical or substantially identical in all the coils but in opposite directions between two coils which are 5 successive in the chain; and means (9) for detecting at least one voltage component that exists between the two secondary terminals (S1, S2) of the coil chain (1-4), a frequency of said voltage component, said mixing frequency, being a linear combination of the first frequency (BF) and the second frequency (HF), with fixed linear combination coefficients, integer and non-zero, said apparatus being adapted to adjust the intensity of the current continuous (Ion) so as to cancel an amplitude of the voltage component which has the mixing frequency, so that when the four coils (1-4) are placed in the magnetic field, a value of the intensity of the DC current (Ion) which cancels the amplitude of the voltage component having the mixing frequency, proportional to an intensity of the magnetic field. 20
    [0002]
    Apparatus according to claim 1, wherein a quotient between the first (BF) and second (HF) frequencies is greater than 10.
    [0003]
    3. Apparatus according to claim 1 or 2, wherein the injection means (5) of the direct current (Ion), the means (6) of injection of the first alternating current (IBF) and the means (7) of injection of the second alternating current (IHF) together comprise four connection cables (CC1-CC4) which are respectively dedicated to each of the four coils (1-4), each cable comprising two electrical wires connected one-to-one to the two terminals successive in the chain of coils that directly connect the coil to which said cable is dedicated, so that all the DC current (Ion), the entire first AC current (IBF) and all the second AC current (IHF) that are injected in the coils (1-4) are transported back and forth by said cables, and respective lengths of said cables are adjusted so that the third intensities of the second alternating current are identical or substantially identical in value ab. solue in all the reels of the chain. 5
    [0004]
    Apparatus according to any one of the preceding claims, wherein the second frequency (HF) is greater than the first frequency (BF), and wherein the means (7) for injecting the second alternating current (IHF) comprise a source (71) of the second alternating current and a primary winding (73) of a transformer (8), a current output of said source being connected to a center point (J) of the primary winding of the transformer, and two end terminals (F, H) of said primary winding being respectively connected to the two secondary terminals (S1, S2) of the coil chain (1-4), and wherein a secondary winding (91) of the transformer (8) belongs to the means (9) for detecting the voltage component which has the mixing frequency.
    [0005]
    Apparatus according to any one of the preceding claims, wherein the means (9) for detecting the voltage component which has the mixing frequency comprise: a first synchronous demodulator (93) which is coupled to the means ( 7) for injecting the second alternating current (IHF), and which is arranged to frequency shift the voltage component which has the mixing frequency, by suppressing a contribution of the second frequency (HF) in said frequency mixture ; and a second synchronous demodulator (94) which is coupled to the injection means (6) of the first alternating current (IBF), and which is arranged to frequency shift the voltage component which has the mixing frequency, by suppressing a contribution of the first frequency (BF) in said mixing frequency, wherein said first (93) and second (94) synchronous demodulators are cascaded to output a continuous electrical signal which is proportional to the amplitude of the voltage component that has the mixing frequency. 5
    [0006]
    Apparatus according to any one of the preceding claims, wherein the second frequency (HF) is greater than the first frequency (BF), and the means (6) for injecting the first alternating current (IBF) are connected to the central terminal (C) of the coil chain (1-4) by a first capacitor (C1) which is adapted to conduct AC current at the first frequency (BF) and the second frequency (HF); and the means (7) for injecting the second alternating current (IHF) are connected to each of the two secondary terminals (S1, S2) of the coil chain (1 -4) by a respective second capacitor (C2) which is adapted to be AC driver at the second frequency (HF) but not at the first frequency (BF).
    [0007]
    Apparatus according to any one of claims 1 to 6, adapted so that the four coils (1-4) are all parallel to a common axis, are juxtaposed to each other and have respective winding directions of the wire. around the cores (1N-4N) which are identical with respect to said common axis.
    [0008]
    8. Apparatus according to any one of claims 1 to 6, adapted so that the four coils (1-4) are all parallel to a common axis, and are divided into two pairs of coils, with the coils of the same pair (1, 2) having winding directions of the electrical wire around the cores which are identical for the two coils of said pair, and inverse in the winding direction of the coils of the other pair (3, 4), and with the coils of the same pair which are juxtaposed while the two pairs of coils are spaced from each other perpendicularly to said common axis. 3038063 - 22 -
    [0009]
    Apparatus according to any one of claims 1 to 6, wherein each core (1N-4N) is in the form of a closed loop and each coil (1-4) is wound on the core of said coil perpendicular to a longitudinal direction of the loop, and the four core coils are juxtaposed to each other over a full loop length of the cores, and have winding directions of the wire that are identical.
    [0010]
    10. A method of measuring a magnetic field, comprising the steps of: / 1 / placing the four coils (1-4) of an apparatus according to any one of claims 1 to 8 in a magnetic field; and / 2 / adjusting the intensity of the DC current (Ion) produced by the DC injection means so as to cancel the amplitude of the voltage component which has the mixing frequency; The value of the DC current intensity (Ipc) which is produced by said DC injection means (5) and which has been adjusted to step / 2 / constituting a measurement result for the magnetic field.
    [0011]
    11. A method of measuring a continuous electric current, comprising the steps of: 20/1 / providing an apparatus according to any one of claims 1 to 9; / 2 / arranging the four coils (1-4) near the continuous electrical current to be measured, called the unknown current (I), or around said unknown current so that said unknown current passes through the loops of the four nuclei (1 N -4N) outside the coils; and / 3 / adjusting the intensity of the direct current (Ion) which is produced by the DC injection means (5) in the coil chain (1-4), so as to cancel the amplitude of the component electrical voltage which has the mixing frequency; The value of the intensity of the direct current (Ion) which is produced by said direct current injection means (5) and which has been adjusted to step / 3 /, constituting a measurement result for the unknown current (I).
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    同族专利:
    公开号 | 公开日
    FR3038063B1|2018-10-26|
    WO2016207508A1|2016-12-29|
    US10488444B2|2019-11-26|
    EP3314281B1|2019-09-18|
    US20180196087A1|2018-07-12|
    EP3314281A1|2018-05-02|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    US20090143665A1|2007-11-26|2009-06-04|Yusuke Seki|Magnetic detection coil and apparatus for magnetic field measurement|
    US20140253113A1|2011-11-30|2014-09-11|Japan Aviation Electronics Industry, Limited|Geomagnetic sensor|
    US20150108974A1|2012-04-12|2015-04-23|Institute Of Geological And Nuclear Sciences Limited|Magnetometer|WO2021084169A1|2019-10-31|2021-05-06|Atware|Device for measuring an amount of superparamagnetic material and use of such a device|RU2166751C1|2000-03-09|2001-05-10|Никитин Петр Иванович|Process of analysis of mixture of biologic and/or chemical components with use of magnetic particles and device for its implementation|
    FR3038060B1|2015-06-26|2018-11-02|Atware|APPARATUS FOR MEASURING A QUANTITY OF SUPERPARAMAGNETIC MATERIAL|FR3063544B1|2017-03-06|2021-01-22|Neelogy|INSULATED DC / AC CURRENT SENSOR WITH NEEL® EFFECT INTEGRATED IN A PCB|
    CN107356800B|2017-07-04|2020-03-17|西安交通大学|Large current detection device and method for magnetic field cancellation|
    CN109755007B|2018-12-03|2020-11-27|北京航空航天大学|Space four-coil system and miniature octopus robot|
    法律状态:
    2016-06-27| PLFP| Fee payment|Year of fee payment: 2 |
    2016-12-30| PLSC| Search report ready|Effective date: 20161230 |
    2017-06-28| PLFP| Fee payment|Year of fee payment: 3 |
    2018-05-29| PLFP| Fee payment|Year of fee payment: 4 |
    2019-04-26| PLFP| Fee payment|Year of fee payment: 5 |
    2020-05-20| PLFP| Fee payment|Year of fee payment: 6 |
    2021-05-19| PLFP| Fee payment|Year of fee payment: 7 |
    优先权:
    申请号 | 申请日 | 专利标题
    FR1555928A|FR3038063B1|2015-06-26|2015-06-26|APPARATUS FOR MEASURING A MAGNETIC FIELD|
    FR1555928|2015-06-26|FR1555928A| FR3038063B1|2015-06-26|2015-06-26|APPARATUS FOR MEASURING A MAGNETIC FIELD|
    EP16739207.5A| EP3314281B1|2015-06-26|2016-06-10|Device for measuring a magnetic field|
    PCT/FR2016/051397| WO2016207508A1|2015-06-26|2016-06-10|Device for measuring a magnetic field|
    US15/738,720| US10488444B2|2015-06-26|2016-06-10|Device for measuring a magnetic field|
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