Current divider using vias

Abstract

Current divider (31) comprising: - plated holes (105, 106) forming a first branch (32) of the current divider and a second branch (33) of the current divider through which the target current flows; - the first branch comprising first plated holes (105a) extending between a first surface (107) of a first conductive layer and a first surface (109) of a second conductive layer, and second plated holes (105b) extending between a second surface (108) of the first conductive layer and the first surface of the second conductive layer, the plated holes (105) of the first branch comprising pairs of adjacent plated holes, each comprising a first plated hole (105a) and a second plated hole (105b). FIGURE IN ABRIDGED DIAGRAM: Fig. 9

Description

Title of the invention: Current divider using vias

[0001] The invention relates to the field of current dividers.

[0002] BACKGROUND

[0003] Aircraft decarbonization is a fundamental challenge for the aeronautical industry. Many onboard systems and equipment are being progressively electrified, and electric motors are therefore being integrated more and more frequently into aircraft. Electrification concerns both propulsion functions and actuation (replacing hydraulic, or rather hydromechanical, actuation devices with electromechanical systems).

[0004] The electrification of aircraft is accompanied by the growing need to know the operational status of onboard equipment and systems at all times. This need arises, on the one hand, from safety justification requirements, and on the other hand, from requirements relating to the operational performance of said equipment and systems.

[0005] Equipment and systems are therefore instrumented with numerous sensors enabling the measurement of different physical quantities.

[0006] The intrusive aspects of these sensors must be minimized to impact the overall mass of the equipment and systems as little as possible, but also to be able to install these sensors in different locations on the aircraft as easily as possible, without calling into question the certification of the equipment and systems they monitor.

[0007] One of the key elements for the control of an electric motor and the control of its energy expenditure is the current sensor, which is classically located near the power electronics associated with the motor, and therefore subject to the same constraints.

[0008] Similarly, for power conversion devices (e.g., PEM, for Power Electronic Module) and protection devices (e.g., SSPC, for Solid State Power Controllers), it is necessary to know the current flowing in certain equipotential bonds. In the case of the PEM, the current of each motor phase must be measured. In the case of the SSPC, the current delivered to its user must be measured.

[0009] Current sensors must typically meet the following requirements: - ability to withstand significant common modes, for example a few hundred volts; - to measure currents, both direct and alternating, with frequencies up to several kHz or even several tens of kHz; - guarantee MTBF (Mean Time Between Flights) performance and measurement accuracy over a wide temperature range (from -55°C to +125°C, and possibly even beyond); - mastering the "current measurement" function for cost optimization, resistance to obsolescence and optimization of integration into user systems.

[0010] The flow valve current sensor is a very good candidate to meet these requirements.

[0011] With reference to [Fig. 1], a flow valve current sensor 1 is similar in design to a transformer comprising a primary winding 2 and a secondary winding 3. The current to be measured Im flows in the secondary winding. An excitation circuit 4 excites the magnetic core 5 via the primary winding 2. A measuring circuit 6 measures a resulting current representative of the current to be measured.

[0012] A flow valve current sensor utilizes the property of a magnetic material forming a magnetic core to saturate above a certain level of magnetic excitation. Referring to [Fig. 2], for an increasing magnetic field H, the slope of the transfer function between the magnetic field H and the magnetic induction B decreases significantly from a value known as the saturation of the magnetic core. The saturation value in [Fig. 2] corresponds to the intervals AH and AB.

[0013] In a traditional flow valve current sensor, the entire current to be measured, Im, flows through a single turn (the secondary winding simply passing through the magnetic core). This is acceptable for low currents (with an amplitude less than IA, for example). For higher currents, the technological challenge is significant: the demagnetization current must be equal to the value of the current to be measured divided by the turns ratio with the demagnetization winding.

[0014] The number of turns in the demagnetizing winding is limited by its size and the resulting inductance. The higher the resulting inductance, the more limited the rate of change of the demagnetizing current, and therefore the more limited the AC bandwidth of the sensor.

[0015] To counteract this effect, it was considered to divide the current to be measured into a main current flowing outside the magnetic core and a target current, a fraction of the main current and a representation of the current to be measured. For this purpose, with reference to [Fig. 3], one possible solution is to use a current divider bridge 7. This idea seems trivial in principle but is not at all so in practice. The main current flows in the first branch 8 of the current divider bridge 7 and the target current flows in the second branch 9.

[0016] Documents WO 2020 / 002484 Al and WO 2020 / 002475 Al reveal a flow valve current sensor that was designed in this context.

[0017] In these documents, the reproducibility of the electrical characteristics of several plated-through holes (vias) of the same diameter in the same printed circuit board is exploited. The fabrication of the plated-through holes on the printed circuit board is highly reproducible. The resistance variation of the plated-through holes is very low, provided that care is taken in the manufacturing process (reusing the same drill bit for all the plated-through holes, etc.).

[0018] With reference to Figures 4 and 5, a current divider 10 is thus obtained, comprising two branches 11, 12, each equivalent to a shunt resistance. The absolute value of each resistance is not well known, but the ratio between these resistances is known with great precision.

[0019] Thus, for example, the realization of a forest of one hundred metallized holes 13 will allow up to a division by one hundred of the current since the intensity circulating in each of these metallized holes will be identical by design.

[0020] The metallized holes 13a of the first branch 12 are positioned outside the core 14. The metallized holes 13b of the second branch 12 are therefore positioned inside the core 14.

[0021] The current to be measured Im is therefore divided into two parts, the distribution being done by the ratio of the number of metallized holes 13 in the printed circuit 15. For example, for a total current of 10A, nine holes are allocated to the passage of the main current and one hole for the measurement (target current): we thus have one tenth of the current flowing in the second branch and nine tenths in the external holes.

[0022] The current divider is manufactured as follows. The magnetic core 14 is simply deposited between a first conductive layer 16 and a second conductive layer 17 (and therefore within the insulating layer 18 between these two copper planes 16, 17) during the manufacturing process of the printed circuit board 15. Once all the layers are assembled with the encapsulated core, the holes are drilled and then plated. The plated holes 13 thus extend between the first conductive layer 16 and the second conductive layer 17. The current to be measured enters the current divider 10 through a trace 19 of the first conductive layer 16 and exits through a trace 20 of the second conductive layer 17.

[0023] However, two difficulties were observed in this flow valve current sensor.

[0024] The first difficulty is the following.

[0025] The first branch 11 of the current divider 10, whose resistance is significantly lower than that of the second branch 12, causes the equivalent of a near short-circuit load on the measuring "transformer". This situation requires The excitation must be more powerful so that this charge does not prevent the saturation of the magnetic core. In practice, the impedance of the first branch 11 in the excitation frequency range (a few MHz) remains quite high, but its weakness nevertheless remains a significant drawback.

[0026] The second difficulty is as follows. It relates more specifically to the current divider. A magnetic pollution phenomenon was observed in the printed circuit 15.

[0027] As we have just seen, the design of the current divider 10 consists of passing a strong current through a forest of identical metallized holes.

[0028] With reference to [Fig. 6], the flow of this strong current through the metallized hole forest 13a locally generates a magnetic field Hl. The sum total of the magnetic fields Hl generated by the metallized hole forest 13a can then disrupt the operation of the magnetic sensor. It is therefore essential to try to cancel out, or at least reduce, the magnetic fields generated by this forest.

[0029] OBJECT

[0030] The invention aims to solve the second difficulty that has just been mentioned.

[0031] SUMMARY

[0032] To achieve this goal, a current divider is proposed, arranged to divide an input current to obtain a target current, and comprising:

[0033] - a printed circuit comprising a first conductive layer, a second conductive layer, an insulating layer extending between the first conductive layer and the second conductive layer, and metallized holes extending into the insulating layer and forming a first branch of the current divider and a second branch of the current divider in which the target current flows;

[0034] - the first branch comprising first metallized holes extending between a first surface of the first conductive layer and a first surface of the second conductive layer, and second plated holes extending between a second surface of the first conductive layer and the first surface of the second conductive layer, the plated holes of the first branch comprising pairs of adjacent plated holes each comprising a first plated hole and a second plated hole;

[0035] - the second branch comprising at least a third metallized hole extending between the first surface of the first conductive layer and a second surface of the second conductive layer.

[0036] Thus, each pair of adjacent metallized holes in the first branch comprises a first metallized hole through which a current flows in one direction, and a second metallized hole through which the same current flows in the opposite direction. The resulting magnetic field generated by the flow of the current in each pair of plated holes, and therefore in the entire first branch (in which a high main current flows).

[0037] A current divider as previously described is further proposed, in which at least a portion of the first surface of the first conductive layer and a portion of the second surface of the first conductive layer are arranged in an interlocking comb arrangement comprising a first comb including at least a first tooth belonging to the first surface of the first conductive layer and from which extend first plated holes of the first branch, and a second comb including at least a second tooth belonging to the second surface of the first conductive layer and from which extend second plated holes of the first branch, the interlocking comb arrangement including at least one pair of adjacent teeth comprising a first tooth and a second tooth.

[0038] A current divider as previously described is further proposed, wherein the second branch further comprises at least a fourth metallized hole extending between the second surface of the second conductive layer and the second surface of the first conductive layer.

[0039] An electrical device is also proposed, comprising:

[0040] - a current divider as previously described;

[0041] - a first magnetic core extending through the thickness of the insulating layer of the printed circuit board, the first plated holes and the second plated holes of the first branch being positioned outside the first magnetic core, and at least one third plated hole of the second branch being positioned inside the first magnetic core;

[0042] at least one third metallized hole of the second branch forming a secondary winding or a primary winding of the electrical device.

[0043] An electrical device as previously described is further proposed, comprising in addition a second magnetic core, the at least one fourth metallized hole of the second branch being positioned inside the second magnetic core.

[0044] An electrical device as previously described is also proposed, the electrical device being a flow valve current sensor.

[0045] An electrical device as previously described is also proposed, the electrical device being a current transformer.

[0046] We further propose an electrical equipment incorporating a current divider as previously described.

[0047] The invention will be better understood in the light of the following description of a particular, non-limiting embodiment of the invention. Brief description of the drawings

[0048] Reference will be made to the attached drawings, among which:

[0049] [Fig. 1] [Fig. 1] represents a prior art flow valve current sensor;

[0050] [Fig.2] [Fig.2] represents the curve of a transfer function between a field magnetic and magnetic induction;

[0051] [Fig.3] [Fig.3] is a figure similar to [Fig.1], with the use of a divisor of fluent ;

[0052] [Fig.4] [Fig.4] represents a cross-sectional view of a prior art printed circuit board used to make the sensor of [Fig.3], along a plane parallel to the thickness of the printed circuit board, and a top view of the printed circuit board;

[0053] [Fig. 5] [Fig. 5] is also a top view of the printed circuit board, on which is also represented the excitation and measurement circuit;

[0054] [Fig.6] [Fig.6] is a cross-sectional and perspective view of the printed circuit board of the art previous, metallized holes of the current divider and a core;

[0055] [Fig.7] [Fig.7] represents an electrical diagram of the valve current sensor flow;

[0056] [Fig.8] [Fig.8] represents two magnetic cores used to implement the flow valve current sensor, and a measuring conductor passing through them;

[0057] [Fig.9] [Fig.9] is a cross-sectional and perspective view of a printed circuit board used to make the current divider, and represents an arrangement of nested combs;

[0058] [Fig. 10] [Fig. 10] is a view of the first conductive layer of the printed circuit;

[0059] [Fig. 11] [Fig. 11] is a view of the second conductive layer of the printed circuit;

[0060] [Fig. 12] the [Fig. 12] represents a first via and a second adjacent via;

[0061] [Fig. 13] [Fig. 13] is a top and perspective view of a portion of the circuit printed, on which only one arrangement of nested combs is visible, part of the first conductive layer being removed;

[0062] [Fig. 14] [Fig. 14] is a cross-sectional and perspective view of the printed circuit, on which the two nested comb arrangements and the two cores can be seen;

[0063] [Fig. 15] [Fig. 15] is a view similar to that of [Fig. 13], on which the two nested comb arrangements are visible. DETAILED DESCRIPTION

[0064] With reference to Figures 7 and 8, the flow valve current sensor 30 is used to measure a current Im. The flow valve current sensor 30 includes a current divider 31 which comprises a first branch 32 and a second branch 33. The input current of the current divider is the current to be measured Im which is divided into a main current Ip which flows in the first branch 32 and a target current le which flows in the second branch 33. The resistance of the second branch 33 is significantly higher than that of the first branch 32, so that the target current le, image of the current to be measured Im, has a significantly lower amplitude than that of the current to be measured Im (and than that of the main current Ip).

[0065] The second branch 33 is therefore a measuring conductor on which the target current flows.

[0066] The flow valve current sensor 30 comprises a first magnetic core 34 and a second magnetic core 35.

[0067] The first magnetic core 34 and the second magnetic core 35 are identical and each has a cylindrical external shape, which here has a circular cross-section. The axes XI, X2 of the cores 34, 35 are therefore axes of revolution of the cores. The shape of the cores could be different, for example cylindrical with a square or rectangular cross-section, or toroidal.

[0068] Axes XI and X2 are parallel.

[0069] The first magnetic core 34 and the second magnetic core 35 are positioned "parallel" to each other, that is to say in particular that their upper faces extend in the same plane and that their lower faces extend in the same plane parallel to the previous one.

[0070] The first magnetic core 34 and the second magnetic core 35 are both positioned between a first plane PI and a second plane P2 which are parallel to each other and which are perpendicular to the axes XI and X2 (and therefore which are parallel to the upper and lower faces of the cores).

[0071] The measuring conductor 33 passes through the first plane PI, then through the first magnetic core 34 to the second plane P2, then through the second plane P2, then through the second magnetic core 35 to the first plane PL. Thus, it can be seen in [Fig.8] that when the first magnetic core 34 and the second magnetic core 35 are positioned horizontally, the measuring conductor 33 descends and passes through the internal central hole of the first magnetic core 34, then ascends and passes through the internal central hole of the second magnetic core 35. The direction of the passage of the target current is therefore reversed in the magnetic cores.

[0072] The flow valve current sensor 30 includes an excitation and measurement circuit comprising excitation components 37 and measurement components 38.

[0073] The excitation and measurement circuit includes a processing unit 39 which belongs to both the excitation components 37 and the measurement components 38.

[0074] The processing unit 39 comprises at least one processing component 40 (for example a processor, a microcontroller, a programmable logic component such as an FPGA (for Field Programmable Gate Arrays) or an ASIC (for Application Specified Integrated Circuit), etc.) and at least one memory 41 integrated in or connected to the processing component 40. At least one of these memories 41 forms a computer-readable recording medium on which is recorded at least one computer program comprising instructions which lead the processing unit 39 to execute the steps of the measurement process which will be described below.

[0075] The processing unit 39 also includes a digital-to-analog converter 42 (which belongs to the excitation components 37) and an analog-to-digital converter 43 (which belongs to the measurement components 38).

[0076] The excitation components 37 comprise a first excitation winding 45 and a second excitation winding 46. The first excitation winding 45 is wound around the first magnetic core 34 and the second excitation winding 46 is wound around the second magnetic core 35. We thus obtain a first transformer 47 having as its primary winding the first excitation winding 45 and as its secondary winding the first portion 48 of the measuring conductor 33 which extends through the first magnetic core 34, and a second transformer 49 having as its primary winding the second excitation winding 46 and as its secondary winding the second portion 50 of the measuring conductor 33 which extends through the second magnetic core 35.

[0077] The excitation components 37 further include a first operational amplifier 52, a second operational amplifier 53, a third operational amplifier 54, and a center-tapped transformer 55.

[0078] The processing unit 39 drives the digital-to-analog converter 42 to produce a primary excitation voltage Va. The primary excitation voltage Va is amplified by the first operational amplifier 52. The amplified primary excitation voltage Vb comprises a first component H1 of frequency f0, a first component H3 of frequency 3.f0 and a first low-frequency DC component.

[0079] The first component H1 at frequency f0 is the main high-frequency excitation component. The first component H3 at frequency 3f0 is a slight 3rd harmonic excitation, which is intended to be canceled by the effect of the onset of saturation of the magnetic cores. The first low-frequency DC component is a low-frequency DC component intended to compensate for the effect of the current to be measured Im (more precisely here, the target current le).

[0080] The amplified primary excitation voltage Vb is applied to the input of the second operational amplifier 53, which forms a current amplifier presenting a unity voltage gain. A capacitor 56 is connected in series with the output of the second operational amplifier 53 and the primary winding 57 of the center-tapped transformer 55. This capacitor 56 forms a series capacitive connection, which allows the low-frequency component to be eliminated.

[0081] The center tap transformer 55 comprises, in addition to the primary winding 57, a first secondary winding 58, a second secondary winding 59 and a center tap 60 between the first secondary winding 58 and the second secondary winding 59.

[0082] The voltage Vc comprising the first component H1 of frequency f0 and the first component H3 of frequency 3.f0, is applied to one terminal of the primary winding 57 of the center tap transformer 55, the other terminal of the primary winding 57 being connected to electrical ground.

[0083] The third operational amplifier 54, the resistors 62, 63, 64 and the capacitors 65, 66, 67 form a 3rd order low-pass active filter.

[0084] The amplified primary excitation voltage is applied to the input of said filter, which makes it possible to retain the first low-frequency component and to suppress the high-frequency components (H1 + H3).

[0085] The voltage Vd including the first low frequency DC component is applied to the midpoint 60 of the midpoint transformer 55.

[0086] A first excitation voltage Vel is thus generated on terminal 67 of the first secondary winding 58. A second excitation voltage Ve2 is thus generated on terminal 68 of the second secondary winding 59.

[0087] The first excitation voltage Vel comprises a first component H1 of frequency f0, a first component H3 of frequency 3.f0, and a first low-frequency DC component. The second excitation voltage Ve2 comprises a second component -H1 of frequency f0 equal to the opposite of the first component H1 of frequency f0, a second component -H3 of frequency 3.f0 equal to the opposite of the first component H3 of frequency 3.f0, and a second low-frequency DC component equal to the first low-frequency DC component.

[0088] The first excitation voltage Vel and the second excitation voltage Ve2 are therefore identical voltages (same amplitude, same frequency) but in opposite phase.

[0089] The center-tapped transformer 55 therefore plays the role of a phase shifter.

[0090] The impedance seen at the midpoint 60 on the two secondary windings 58, 59 of the transformer 55 is zero because the two secondary windings 58, 59 are wound in opposite directions with respect to each other. The fluxes generated are identical in magnitude and opposite in sign, which results in a zero magnetic flux (the load impedances are considered identical, therefore the currents are also identical). zero impedance, therefore short-circuit behavior (therefore direct transmission without disturbance of the low-frequency voltage).

[0091] The first excitation voltage Vel is applied to the first terminal 70 of the first excitation winding 45. The second terminal 71 of the first excitation winding is connected to ground via a first resistor 72.

[0092] The second excitation voltage Ve2 is applied to the first terminal 73 of the second excitation winding 46. The second terminal 74 of the second excitation winding 46 is connected to ground via a second resistor 75.

[0093] A first resulting current II flows in the first excitation winding 45 and produces a first measurement voltage Vml across the first resistor 72, which is representative of the first resulting current II. A second resulting current 12 flows in the second excitation winding 46 and produces a second measurement voltage Vm2 across the second resistor 75, which is representative of the second resulting current 12.

[0094] The first measurement voltage Vml includes the first component H1 of frequency f0, the first component H3 of frequency 3.f0, the first low frequency DC component, as well as a first component H2 of frequency 2.f0.

[0095] The second measurement voltage Vm2 comprises the second component -H1 of frequency f0, the second component -H3 of frequency 3.f0, the second low frequency DC component, as well as a second component -H2 of frequency 2.f0 which is equal to the opposite of the first component of frequency 2.f0.

[0096] The low-frequency DC components remain of the same sign because they are emitted in phase on the first excitation winding 45 and the second excitation winding 46.

[0097] The measuring components 38 produce an output voltage Vs representative of the target current le (and therefore of the current to be measured Im) from the first measuring voltage Vml and the second measuring voltage Vm2.

[0098] The measuring components 38 comprise a measuring amplifier device with three operational amplifiers: a first operational amplifier 80, a second operational amplifier 81, and a third operational amplifier 82. The third operational amplifier 82 is a differential instrumentation amplifier. The measuring components also comprise a fourth operational amplifier 83.

[0099] The first operational amplifier 80 has its non-inverting input connected to the first resistor 72 and its inverting input connected to its output. The first measurement voltage Vml is therefore applied to the non-inverting input of the first operational amplifier 80.

[0100] The output of the first operational amplifier 80 is connected to the inverting input of the differential amplifier 82 via the resistor 84.

[0101] The inverting input of the differential amplifier 82 loops back to its output via the resistor 85.

[0102] The second operational amplifier 81 has its non-inverting input connected to the second resistor 75 and its inverting input which loops back to its output. The second measurement voltage Vm2 is therefore applied to the non-inverting input of the second operational amplifier 81.

[0103] The output of the second operational amplifier 81 is connected to the non-inverting input of the differential amplifier 82 via the resistor 86. The non-inverting input of the differential amplifier 82 is connected to ground via the resistor 87.

[0104] The output of the first operational amplifier 80 is connected to the non-inverting input of the fourth operational amplifier 83 via the resistor 87. The output of the second operational amplifier 81 is connected to the non-inverting input of the fourth operational amplifier 83 via the resistor 88.

[0105] The output of the differential amplifier 82 is connected to the inverting input of the fourth operational amplifier 83 via the resistor 89.

[0106] The inverting input of the fourth operational amplifier 83 loops back to its output via the resistor 90.

[0107] The first operational amplifier 80 and the second operational amplifier 81 act as non-inverting input buffers.

[0108] The output voltage Vf of the differential amplifier 82 is: -2 (H1 + H3 + H2).

[0109] The fourth operational amplifier 83 has on its non-inverting input the first low frequency DC component (multiplied by 2) and therefore on its inverting input -2 (H1 + H3 + H2).

[0110] We therefore have the output voltage Vs at the output of the fourth operational amplifier 83: [YES] 2 (H1 + H3 + DC + H2).

[0112] The analog-to-digital converter 43 digitizes the output voltage Vs and provides the digitized output voltage to the processing unit 39.

[0113] The processing unit 39 recovers the first component H2 of frequency 2.f0 and the first component H3 of frequency 3.f0.

[0114] The first component H2 of frequency 2.f0 is representative of the current to be measured Im.

[0115] It is also used to produce and control the demagnetizing currents which compensate for the magnetic fluxes produced by the target current in the first core 34 and the second core 35.

[0116] The flow valve current sensor 30 also implements a control system to control the primary excitation voltage Va so as to cancel the frequency component 3.f0 of the first resulting current II and the frequency component 3.f0 of the second resulting current 12, which corresponds to an optimal operating point of the flow valve current sensor 30. The optimal operating point corresponds to the bend 92 of the transfer function between the magnetic field H and the magnetic induction B visible in [Fig. 2]. The optimal operating point corresponds to a maximum gain of the flow valve current sensor.

[0117] The 30 flow valve current sensor has the following advantages.

[0118] Since the first transformer 47 and the second transformer 49 are wired in the same way, the voltages induced on the two secondaries (the two portions of the measuring conductor 33, one passing through the first magnetic core 34, the other through the second magnetic core 35) are the same but in opposite phase, hence with a zero vector sum. Therefore, no current is generated in the measuring conductor.

[0119] Consequently, the excitations emitted on the two primary windings have impedances tending towards infinity (no-load transformers). Only the magnetic fluxes emitted by the currents to be measured modify the operating point of the excitation H1 on the curve B=f(H) of [Fig.2].

[0120] It is further noted that this also eliminates any signal injection at the frequency fO (Hl) on the power line, which is favorable for limiting conducted electrical disturbances.

[0121] By performing a differential measurement at the foot of each transformer, the sensor 30 is desensitized to external fields because the two magnetic cores undergo the same disturbances.

[0122] The flow valve current sensor 30 also has the following additional advantage. Comparison between the primary and secondary DC components makes it possible to detect drifts in the analog system.

[0123] With reference to figures 9 to 11, the flow valve current sensor 30 comprises a printed circuit board 100. The printed circuit board 100 may be the one on which the components just described are mounted, but not necessarily, it may also be a separate printed circuit board.

[0124] The printed circuit 100 includes a first conductive layer 101 which extends here in the first plane PI previously mentioned, a second conductive layer 102 which extends in the second plane P2 previously mentioned, and an insulating layer 103 which extends between the first conductive layer 101 and the second conductive layer 102.

[0125] The first magnetic core 34 and the second magnetic core 35 extend into the insulating layer 103 (only the first magnetic core 34 is visible on the [Fig.9]).

[0126] The primary windings 45, 46 of the first transformer 47 and of the second transformer 49, as well as the branches 32, 33 of the current divider 31, include metallized holes extending in the insulating layer 103 between the first conductive layer 101 and the second conductive layer 102.

[0127] The first excitation winding 45 and the second excitation winding 46 include metallized holes (not shown for clarity) extending into the insulating layer 103 between the first conductive layer 101 and the second conductive layer 102.

[0128] The first branch 32 of the current divider 31 includes metallized holes 105 extending into the insulating layer 103 between the first conductive layer 101 and the second conductive layer 102.

[0129] The second branch 33 of the current divider 31 also includes one or more metallized holes 106 extending into the insulating layer 103 between the first conductive layer 101 and the second conductive layer 102.

[0130] We are now more particularly interested in the current divider 31.

[0131] The current divider 31 therefore includes the printed circuit board 100 which includes the first conductive layer 101, second conductive layer 102, insulating layer 103 extending between first conductive layer 101 and second conductive layer 102, and metallized holes 105, 106 extending in insulating layer 103 and forming the first branch 32 of the current divider 31 in which the main current Ip flows and the second branch 33 of the current divider 31 in which the target current Ip flows.

[0132] As can be seen in Figures 10 and 11, the first insulating layer 101 comprises a first surface 107 and a second surface 108, which are electrically insulated from each other. The second conductive layer 102 also comprises a first surface 109 and a second surface 110, which are electrically insulated from each other.

[0133] The current to be measured Im enters the current divider 31 by flowing over the first surface 107 of the first conductive layer 101, and exits on the second surface 108 of the first conductive layer 101.

[0134] The number of plated-through holes 105 in the first branch 32 of the current divider 31 is much higher than the number of plated-through holes 106 in the second branch 33, which makes it possible to increase in the current divider 31 the ratio between the resistance of the second branch 33 and that of the first branch 32, and therefore to reduce the current flowing in the second branch 33 (target current the image of the current to be measured Im).

[0135] The first branch 32 of the current divider 31 includes first metallized holes 105a extending between the first surface 107 of the first conductive layer 101 and the first surface 109 of the second conductive layer 102, and second metallized holes 105b extending between the second surface 108 of the first conductive layer 101 and the first surface 109 of the second conductive layer 102. The second branch includes at least one third metallized hole 106a extending between the first surface of the first conductive layer 101 and the second surface of the second conductive layer 102.

[0136] With reference to [Fig. 12], each first plated hole 105a is adjacent to a second plated hole 105b, i.e. the plated hole closest to a first plated hole 105a is a second plated hole 105b.

[0137] Thus, the metallized holes 105 of the first branch comprise pairs of adjacent metallized holes, each comprising a first metallized hole 105a and a second metallized hole 105b. The main current Ip, flowing in the first branch 32, flows in a first direction in each first metallized hole 105a (and locally creates a magnetic field H11), and in a second direction opposite to the first direction in each second metallized hole 105b (and locally creates a magnetic field H12).

[0138] Consequently, the forest of metallized holes in the first branch 32 is arranged so that one metallized hole (the first metallized hole 105a, for example) carrying the current in one direction a, in the immediate vicinity, another metallized hole (the second metallized hole 105b in this example) carrying the current in the opposite direction. This results in the cancellation of the resulting magnetic field, since the currents flowing inside the first metallized hole 105a and the second metallized hole 105b are identical except for their signs.

[0139] Here, as can be seen in Figures 10, 13 and 14, at least a portion of the first surface 107 of the first conductive layer 101 and a portion of the second surface 108 of the first conductive layer 101 are arranged in a nested comb arrangement comprising a first comb 111 including at least a first tooth 112 belonging to the first surface 107 of the first conductive layer 101 and from which extend the first plated holes 105a of the first branch 32 of the current divider 31, and a second comb 114 including at least a second tooth 115 belonging to the second surface 108 of the first conductive layer 101 and from which extend the second plated holes 105b of the first branch 32.

[0140] The combs shown here each comprise five teeth. Five metallized holes extend from each tooth.

[0141] The arrangement in interlocking combs includes at least one pair of adjacent teeth comprising a first tooth 112 and a second tooth 115, that is to say that the tooth closest to each first tooth 112 is a second tooth 115 parallel to said first tooth 112.

[0142] Each first tooth 112 therefore belongs to the first surface 107 of the first conductive layer 101. Five first plated holes 105a extend here from said first tooth 112 to the first surface 109 of the second conductive layer 102. Similarly, each second tooth 115 belongs to the second surface 108 of the first conductive layer 101. Five second plated holes 105b extend here from said second tooth 115 to the first surface 109 of the second conductive layer 108.

[0143] We can therefore see that each first plated hole 105a of a first tooth 112 is adjacent to a second plated hole 105b of a second tooth 115, and vice versa.

[0144] Here, as has been understood, the second branch 33 of the voltage divider 31 is a measuring conductor on which flows the target current le which is measured by the flow valve current sensor 30. As has been seen, with reference to Figures 14 and 15, the flow valve current sensor 30 comprises two magnetic cores: a first magnetic core 34 belonging to a first transformer 47 and a second magnetic core 35 belonging to a second transformer 49.

[0145] The first branch 32 is located outside the magnetic cores 34, 35. The second branch 33 comprises a first portion 48 located inside the first magnetic core 34 to form a single turn of the secondary winding of the first transformer 47, and a second portion 50 located inside the second magnetic core 35 to form a single turn of the secondary winding of the second transformer 49.

[0146] The current divider arrangement just described is therefore present not once but twice in the printed circuit 100 of the flow valve current sensor 30.

[0147] The flow valve current sensor 30 therefore comprises two nested comb arrangements. The second branch 33 of the current divider 31 therefore comprises at least a third plated hole 106a and at least a fourth plated hole 106b.

[0148] The at least one third metallized hole 106a extends between the first surface 107 of the first conductive layer 101 and the second surface 110 of the second conductive layer 102, the at least one third metallized hole 106a being positioned inside the first magnetic core 34. Here we have only one third metallized hole 106a.

[0149] The at least one fourth metallized hole 106b extends between the second surface 110 of the second conducting layer 102 and the second surface 108 of the first conducting layer 101, the at least one fourth metallized hole 106b being positioned inside the second magnetic core 35. Here we have only one fourth metallized hole 106b.

[0150] Consequently, the third metallized hole 106a and the fourth metallized hole 106b are at the same potential. These metallized holes 106a, 106b are connected by the second surface 110 of the second conductive layer 102. This second surface 110 is surrounded by the first surface 109, and here has, for example, the shape of a rectangle ([Fig. 14]), or of a rectangle whose widths are semicircles extending outwards from the rectangle (Figures 11 and 15).

[0151] We thus have electrical continuity of the measuring conductor via the second surface 110 of the second conductive layer 102.

[0152] The target current flows over the first surface 107 of the first conductive layer 101, in the third metallized hole 106a, over the second surface 110 of the second conductive layer 102, in the fourth metallized hole 106b, and over the second surface 108 of the first conductive layer 101.

[0153] In order to limit the fields generated by the metallized holes with the current division function, there are therefore two groups of current dividers located on either side of the nuclei with comb networks allowing to locally cancel the flux emitted by each of the metallized holes of the divider.

[0154] It is noted that the configuration of [Fig.8] is indeed found: when the printed circuit 100 and therefore the first magnetic core 34 and the second magnetic core 35 are positioned horizontally, the target current flows from top to bottom in the first magnetic core 34, and from bottom to top in the second magnetic core 35.

[0155] Of course, the invention is not limited to the embodiment described but encompasses any variant falling within the scope of the invention as defined by the claims.

[0156] The flow valve current sensor described here incorporates a current divider. However, the flow valve current sensor could be implemented without a current divider. Similarly, the current divider is not necessarily integrated into a flow valve current sensor.

[0157] The electrical equipment incorporating the flow valve current sensor and / or the current divider is possibly, but not necessarily, integrated into an aircraft system.

[0158] The excitation components and measurement components of the flow valve current sensor could be different from those described here.

[0159] The current divider is not necessarily integrated into a flow valve current sensor but could be integrated into another electrical device. This other electrical device is, for example, a current transformer. It could also be an electrical device that does not perform measurements but requires current division (power supply circuit, protection circuit, etc.). The input current Im of the current divider is therefore not, in this case, a current "to be measured".

[0160] The electrical device incorporating the current divider may not have a magnetic core, or it may have a number of magnetic cores other than two (for example, a single core). If the electrical device has a single core, the second branch of the current divider comprises only the third plated hole(s) (106a).

[0161] The plated-through holes in the second branch of the current divider here form a secondary winding, but they could also form a primary winding. This is the case, for example, if the electrical device is a current transformer intended to measure the target current (and therefore the current to be measured).

Claims

Demands

1. Current divider (31), arranged to divide an input current (Im) to obtain a target current (le), and comprising: - a printed circuit (100) comprising a first conductive layer (101), a second conductive layer (102), an insulating layer (103) extending between the first conductive layer and the second conductive layer, and plated-through holes (105, 106) extending in the insulating layer and forming a first branch (32) of the current divider and a second branch (33) of the current divider in which the target current flows;- the first branch comprising first metallized holes (105a) extending between a first surface (107) of the first conductive layer and a first surface (109) of the second conductive layer, and second metallized holes (105b) extending between a second surface (108) of the first conductive layer and the first surface of the second conductive layer, the first surface (107) of the first conductive layer and the second surface (108) of the first conductive layer being electrically isolated from each other, the metallized holes (105) of the first branch comprising pairs of adjacent metallized holes each comprising a first metallized hole (105a) and a second metallized hole (105b);- the second branch comprising at least a third metallized hole (106a) extending between the first surface of the first conductive layer and a second surface (110) of the second conductive layer, the first surface (109) of the second conductive layer and the second surface (110) of the second conductive layer being electrically insulated from each other.

2. Current divider according to claim 1, wherein at least a portion of the first surface (107) of the first conductive layer (101) and a portion of the second surface (108) of the first conductive layer (101) are arranged in a nested comb arrangement comprising a first comb (111) including at least one first tooth (112) belonging to the first surface (107) of the first conductive layer and from which extend first plated holes (105a) of the first branch, and a second comb (114) comprising at least a second tooth (115) belonging to the second surface (108) of the first conductive layer and from which extend second metallized holes (105b) of the first branch, the arrangement in nested combs comprising at least one pair of adjacent teeth comprising a first tooth (112) and a second tooth (115).

3. Current divider according to any one of the preceding claims, wherein the second branch further includes at least a fourth metallized hole (106b) extending between the second surface (110) of the second conductive layer (102) and the second surface (108) of the first conductive layer (101).

4. Electrical device, comprising: - a current divider (31) according to any one of the preceding claims; - a first magnetic core (34) extending into the thickness of the insulating layer (103) of the printed circuit board (100), the first plated holes (105a) and the second plated holes (105b) of the first branch (32) being positioned outside the first magnetic core, and at least one third plated hole (106a) of the second branch (33) being positioned inside the first magnetic core; the at least one third plated hole of the second branch forming a secondary winding or a primary winding of the electrical device.

5. Electrical device according to claim 4, further comprising a second magnetic core (35), the current divider being a current divider according to claim 3, at least one fourth metallized hole (106b) of the second branch (33) being positioned inside the second magnetic core.

6. Electrical device according to any one of claims 4 or 5, the electrical device being a flow valve current sensor.

7. Electrical device according to any one of claims 4 or 5, the electrical device being a current transformer.

8. Electrical equipment incorporating a current divider according to any one of claims 1 to 3.

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