Current measurement system

Abstract

A current measurement system includes a multiphase open-loop current sensor for measuring phase currents (I1, I2, I3) flowing in a plurality of (n) primary conductors in a multiphase electrical system. The sensor includes: a housing (2); a magnetic core (3) including a first core component (3a) and a second core component (3b); and a plurality of (n+1) magnetic field detectors (4) mounted in the housing (2) between the first core component and the second core component, on a portion of the primary conductors traversing the housing of the current sensor. The system further includes a non-volatile memory and a computing unit storing at least one coupling matrix (K) predefined during calibration, the at least one coupling matrix linking the phase currents (I1, I2, I3) flowing in the primary currents with magnetic induction fields (B1, B2, B3, B4) detected by the magnetic field detectors, the computing unit being configured to use the coupling matrix to calculate the values ​​of the n phase currents using the outputs of the n+1 magnetic field detectors. The computing unit is also configured to use n+1 reduced-order mode coupling matrices to estimate n phase currents in a reduced-order mode, thereby allowing the detection of faults, leakage currents or overcurrents in the magnetic field detector.

Description

[0001] This invention relates to a current measurement system for multiphase electrical systems, including a multiphase open-loop current transducer.

[0002] Many electrical systems are supplied with multiphase current (especially three-phase current), such as electric motors in vehicle applications such as electric vehicles. In such applications, robust and reliable current sensors are required, but whose manufacture and installation are also economical.

[0003] Safety is a critical factor; therefore, current sensors should detect faults quickly and reliably so that the control system can shut down or change the settings of the faulty system. Overcurrent and leakage current typically indicate a fault in the electrical system.

[0004] The influence of external magnetic fields (e.g., which may originate from other electrical conductors and components near the current sensor) should not adversely affect the accuracy and reliability of the current sensor.

[0005] Current sensors, such as those found in electric vehicles, which are implemented in harsh environments, also need to withstand mechanical shocks, vibrations, and large thermal changes.

[0006] For existing sensors, responding to the needs of economical manufacturing and installation while also meeting high requirements for safety, durability, reliability, and accurate current measurement is a challenge.

[0007] A three-phase open-loop current sensor is known, comprising a core assembly assembled on opposite sides of three primary conductors arranged in a common plane to generate a current output in each phase. Note that if the current in two of the phases is measured, the current in the third phase can be inferred from the two other phases. However, such conventional open-loop current sensors are relatively expensive to install and drive, and may also lack the response time necessary for rapid fault handling. Furthermore, the detection of sensor faults may be unreliable.

[0008] In view of the above, one object of the present invention is to provide a multiphase (particularly, three-phase) current measurement system with an open-loop current sensor, which is economical to manufacture and install, robust, safe and reliable, while ensuring accurate measurement.

[0009] Advantageously, a multiphase current measurement system is provided that can detect faults, especially leakage current or overcurrent, very quickly.

[0010] Advantageously, a multiphase open-loop current sensor is provided for a compact multiphase current measurement system.

[0011] The objective of this invention has been achieved by providing a multiphase current measurement system according to claim 1.

[0012] The object of the present invention has been achieved by providing a method for measuring multiple currents flowing in multiple (n) primary conductors in a multiphase electrical system, as described in claim 14.

[0013] This document discloses a current measurement system comprising a multiphase open-loop current sensor for measuring phase currents (I1, I2, I3) flowing in multiple (n) primary conductors of a multiphase electrical system. The sensor includes: a housing; a magnetic core comprising a first core component and a second core component; and multiple (n+1) magnetic field detectors mounted within the housing, where a portion of the primary conductor traverses the current sensor housing, located between the first and second core components. The system also includes a non-volatile memory and a computation unit storing information about at least one coupling matrix (K) of predefined size n×n+1, defined during calibration. This coupling matrix links the phase currents (I1, I2, I3) flowing in the primary currents with magnetic induction fields (B1, B2, B3, B4) detected by the magnetic field detectors. The computation unit is configured to use the coupling matrix to calculate the values ​​of the n phase currents using the outputs of the n+1 magnetic field detectors. The computing unit is also configured to use n+1 reduced-order mode coupling matrices to estimate n phase currents in a reduced-order mode, each of size n×n based on the output of a subset n of the n+1 magnetic field detectors, thereby allowing the detection of faults, leakage currents or overcurrents in the magnetic field detectors.

[0014] This paper also discloses a method for measuring multiple currents (I1, I2, I3) flowing in multiple (n) primary conductors in a multiphase electrical system.

[0015] - Provide a current measurement system, the current measurement system including a sensor, the sensor including: a housing, a magnetic core including a first magnetic core component and a second magnetic core component, and a plurality (n+1) magnetic field detectors mounted in the housing between the first and second magnetic core components, a portion of the current sensor housing mounted on the primary conductor, wherein the sensor is connected to the circuitry of the multiphase electrical system;

[0016] - Prior to the operation of the sensor used to measure the phase current flowing in the primary conductor, a calibration method is performed to calculate at least one coupling matrix (K) of size n×n+1, which links the phase currents (I1, I2, I3) flowing in the primary current with the magnetic induction fields (B1, B2, B3, B4) detected by the magnetic field detector.

[0017] - Store the at least one coupling matrix in the non-volatile memory of the sensor or the non-volatile memory of the circuit of the multiphase electrical system;

[0018] - During the operation of the sensor used to measure the phase current flowing in the primary conductor, in the calculation unit of the current measurement system, the values ​​of the n phase currents are calculated using the measurement outputs of the n+1 magnetic field detectors with the at least one coupling matrix;

[0019] - In the computational unit, a reduced-order coupling matrix of size n×n is used to calculate redundant measurements of the multiple currents (I1, I2, I3) to detect faults in the magnetic field detectors. For an n-phase system with n+1 magnetic field detectors, n of them are used to calculate n+1 reduced-order mode coupling matrices (K). 123 K 124 K 134 K 234 ).

[0020] In an advantageous embodiment, the non-volatile memory storing information about at least one coupling matrix (K) is disposed in at least one application-specific integrated circuit (ASIC) forming at least one magnetic field detector in the magnetic field detector, or disposed in the memory of the circuitry of the sensor.

[0021] In an advantageous embodiment, the non-volatile memory storing information about at least one coupling matrix (K) is readable by external circuitry via a connector of a current sensor, so as to transfer the information about the at least one coupling matrix to the external circuitry and calculate the value of the phase current in the external circuitry.

[0022] In an advantageous embodiment, the non-volatile memory storing information about at least one coupling matrix (K) is arranged in the electrical system outside the sensor.

[0023] In an advantageous embodiment, the system further includes a computing unit configured to perform at least two different computing methods to estimate the current, including pseudo-inverse methods such as Moore-Penrose inverse calculation and differential methods.

[0024] In an advantageous embodiment, the first and second magnetic core components are in the form of substantially straight rectangular strips formed by stacking laminated sheets of soft magnetic material.

[0025] In an advantageous embodiment, each of the magnetic core components is received in a corresponding housing component, the housing components being formed as individual parts assembled together, one of the housing components housing the plurality of magnetic field detectors, and the primary conductor portion extending through the housing.

[0026] In an advantageous embodiment, the channel through which the primary conductor extends is formed by a recess or through-cavity in one of the housing components, the other housing component having a substantially flat mating surface.

[0027] In an advantageous embodiment, the sensor includes a circuit board arranged in a plane substantially orthogonal to the plane in which the air gap between the magnetic core components is formed, along the side of the housing that overlaps with the connection terminals of the magnetic field detector.

[0028] In an advantageous embodiment, the magnetic field detector is pre-assembled to the circuit board during manufacturing, whereby, during the assembly of the circuit board against the housing base component, the magnetic field detector is inserted into a cavity in the housing component for receiving the magnetic field detector, the cavity including a cavity located on either side of the primary conductor and a cavity between adjacent primary conductors.

[0029] In an advantageous embodiment, the sensor is used in a three-phase electrical system and includes four magnetic field detectors, two of which are arranged outside the three primary conductors and each of the other two is arranged between corresponding adjacent primary conductors.

[0030] In an advantageous embodiment, the magnetic field detector is in the form of an ASIC.

[0031] In an advantageous embodiment, the comparator can be connected to each magnetic field detector and configured to generate a control signal at a specific voltage threshold determined for each magnetic field detector, so as to generate a shutdown control signal for an electrical system controlled by current in the event of an electrical fault or overcurrent.

[0032] In an advantageous embodiment, the computational unit of the current measurement system's circuitry performs differential measurements on the phase currents, wherein the coupling matrix K′ for the differential measurements is determined using the calibration method.

[0033] In an advantageous embodiment, the reduced-order mode matrix is ​​formed by n×n coefficients.

[0034] Other objects and advantageous features of the invention will be apparent from the claims, detailed description and drawings, wherein:

[0035] Figure 1a This is a perspective view of the current sensor of a current measurement system according to an embodiment of the present invention;

[0036] Figure 1b Through Figure 1a A cross-sectional view of the current sensor;

[0037] Figure 1c It does not have a primary conductor section. Figure 1a A 3D view of the current sensor;

[0038] Figure 1d The base and cover components were disassembled. Figure 1a A view of the sensor;

[0039] Figure 2 This is a perspective view of a variant of the current sensor according to an embodiment of the present invention, with the housing component removed.

[0040] Figure 3a This is a perspective view of a current sensor according to another embodiment of the present invention;

[0041] Figure 3b yes Figure 3a A side view of the sensor;

[0042] Figure 4 This is a simplified schematic diagram illustrating the magnetic core component, magnetic field detector, and primary conductor of a current sensor according to an embodiment of the present invention;

[0043] Figure 5 The illustration shows a flowchart of a calibration method for a current sensor according to an embodiment of the present invention;

[0044] Figure 6 This is a flowchart of the safety analysis process of a current sensor according to an embodiment of the present invention;

[0045] Figure 7 A flowchart illustrating the measurement process of a current sensor according to an embodiment of the present invention is shown;

[0046] Figure 8 This is a schematic diagram of a portion of the signal processing circuit of a current sensor according to an embodiment of the present invention, particularly illustrating the comparator function for detecting faults.

[0047] The current measurement system according to an embodiment of the present invention includes a current sensor 1 for connection to a circuit (not shown) of an electrical system (not shown). The electrical system may be, for example, a motor or a controller for a motor or other type of electrical machine. The current measurement system includes circuit elements for processing measurement signals, which include a computing unit. The computing unit may be included within the sensor 1 or as part of the electrical system for processing the measurement signals external to the sensor. In the latter embodiment, the current sensor 1 may output measurement signals from each of the magnetic field detectors 4, and then process these measurement signals in circuitry external to the sensor to calculate a current measurement value of the current flowing in the primary conductor.

[0048] The computing unit may include or be composed of any form of computing device (integrated circuit, FPGA, microcontroller, etc.) suitable for performing calculations and processing measurement signals.

[0049] Referring to the attached diagram, specifically from Figures 1a to 4 Initially, according to an embodiment of the present invention, a multiphase (in this case, a three-phase) open-loop current sensor 1 includes: a housing 2; a magnetic core 3, including a first core component 3a and a second core component 3b; and a plurality of magnetic field detectors 4 mounted in the housing 2.

[0050] Optionally, the current sensor may also include a signal processing circuit 5 connected to the magnetic field detector 4, and may optionally include multiple primary conductor portions 6a, 6b, 6c integrated or pre-assembled into the current sensor.

[0051] In some embodiments, circuit 5 may include circuit traces for interconnecting the magnetic field detector with a connector for connecting to an external circuit, but without electronic components for signal processing, which is performed in the circuitry of the electrical system to which the sensor is connected.

[0052] In one embodiment, the current sensor may be configured without a primary conductor portion and be assembled around a primary conductor 6 of a multiphase electrical system (not shown). The current sensor housing includes a channel 11 for receiving the external primary conductor 6 passing through it. In the illustrated embodiment, the current sensor is used in a three-phase electrical system, for example, for the control of a three-phase motor. The primary conductor carries the current to be measured. However, within the scope of the invention, current sensors with two, four, five, six, or more phases can also be used, utilizing the principles described for the three-phase embodiment.

[0053] The magnetic core components 3a and 3b are made of materials with high permeability, particularly soft magnetic materials such as FeSi alloys or FeNi, which are well known in themselves.

[0054] Advantageously, the magnetic core components 3a, 3b can be in the form of straight or substantially straight rectangular strips, which are particularly economical to manufacture, for example, by stamping soft magnetic material sheets stacked to form the strips.

[0055] A gap is formed between the magnetic core components 3a and 3b, in which the primary conductor 6 and the magnetic field detector 4 are located. The gap extends substantially along plane P, thereby, in an advantageous embodiment, the primary conductor and the magnetic field detector can be substantially aligned along plane P.

[0056] In an advantageous embodiment, the magnetic core components can be identical to further reduce manufacturing costs and simplify the number of components used in the fabrication of the current sensor.

[0057] Advantageously, the magnetic field detector 4 can be in the form of an application-specific integrated circuit (ASIC), in which the integrated circuit of the magnetic field detector is overmolded and connected to connection pins for power and signal transmission; such ASICs are well known in the field of current sensors. ASICs can typically be based on Hall effect detectors, which are also well known. In embodiments, other magnetic field detectors such as TMR (tunneling magnetoresistance) or GMR (giant magnetoresistance) can be used.

[0058] Each of the core components 3a, 3b is received in a corresponding housing component 2a, 2b. In an advantageous embodiment, the housing components may be formed as separate parts, which are assembled together and secured by latching element 12 or other fixing members (such as screws or clamps), or the housing components may be secured together by welding or joining such that they are inseparable after assembly.

[0059] In a variant, as illustrated, the housing components can be assembled in situ, for example, to mount around the primary conductor of an external system.

[0060] In a variant in which the primary conductor portions 6a, 6b, and 6c are directly integrated into the current sensor, the housing components 2a and 2b may be permanently shaped, welded, or arranged around the primary conductor portions for connection to the external primary conductor carrying the current to be measured before the current sensor is assembled into an external device.

[0061] The magnetic core components 3a and 3b, positioned on either side of the magnetic field detector 4, have sufficient width and length to completely cover and extend beyond the surface area of ​​the magnetic field detector when viewed in a direction D orthogonal to the plane P aligned with the primary conductor 6 and the magnetic field detector. This allows the external magnetic field (e.g., due to electrical components near the current sensor) to be distributed substantially uniformly in the air gap between the two core components 3a and 3b. The magnetic core components 3a and 3b have a cross-section configured to remain unsaturated with high reliability at the specified maximum current to be measured by the sensor.

[0062] As will be discussed below, differential measurements using a magnetic field detector allow for the elimination of magnetic field values ​​originating from external fields.

[0063] The channel 11 through which the primary conductors 6, 6a, 6b, and 6c extend can be formed by a recess or through cavity in one of the housing components 2a (base component 2a), and the other housing component 2b has a substantially flat mating surface that connects with the mating surface of the base portion 2a. The primary conductors 6a, 6b, and 6c can be provided in the shape of rectangular strips, for example, as shown in the figure; however, they can also be provided as cylindrical, elliptical, trapezoidal, or other contoured primary conductor strips.

[0064] The connecting surface of the second housing component 2b, in which the magnetic component 3b is assembled, may be coated or provided with an insulating layer to insulate the magnetic core component 3b from the primary conductors 6a, 6b, and 6c.

[0065] Circuit 5 includes circuit board 7, which is advantageously arranged along the side 13 of the housing that overlaps with the connection terminals of magnetic field detector 4 in a plane substantially orthogonal to the plane P along which the air gap is aligned.

[0066] The magnetic field detector 4 can be pre-assembled to the circuit board 7 during manufacturing, whereby, during the assembly of the circuit board against the housing base component 2a, the magnetic field detector 4 is inserted into a cavity 13 in the housing component for receiving the magnetic field detector, the cavity including cavities 13a, 13d located on either side of the primary conductor and cavities 13b, 13c between adjacent primary conductors. Thus, for a three-phase electrical system, there are four magnetic field detectors 4a, 4b, 4c, 4d, and in a particular advantageous embodiment, they are in the form of ASICs (hereinafter referred to as ASIC1, ASIC2, ASIC3, ASIC4).

[0067] The housing 2 may include other components, such as mounting lugs 14 for securing the current sensor to an external support.

[0068] Circuit 5 also includes connector 8 for connection to external circuitry, which includes signal processing circuitry for driving the current sensor and power supply for the magnetic field detector, as well as current measurement output from the current sensor.

[0069] In the illustrated embodiment, connector 8 includes a housing portion directly integrated into housing base component 2a and including pin terminals for connection to an external circuit board or for insertion connection to an external connector. Other types of contacts may be provided for insertion, clamping, or soldering connections, as known per se in the field of connection systems.

[0070] In one embodiment, the circuit board 7 of circuit 5 includes contact portions for the magnetic field detector 16, which are interconnected via circuit traces to electronic components on the circuit board. These electronic components allow for processing or preprocessing of the measurement signal before output via connector 8. A microcontroller for signal processing may, for example, be mounted on the circuit board 7. In another embodiment, the circuit board 7 of circuit 5 includes contact portions for the magnetic field detector 16 interconnected via circuit traces to connector 8, thereby performing processing of the measurement signal output by the magnetic field detector in an external circuit to which the sensor is connected.

[0071] According to an embodiment, a computing unit implemented externally in the sensor or in the circuitry of the electrical system to which the sensor is connected can be advantageously configured to perform several methods to process the currents measured by multiple magnetic field detectors, thereby obtaining accurate primary current values ​​for each phase, for example, such as Figure 7 As shown in the diagram.

[0072] In an advantageous embodiment, the method includes a pseudo-inverse method and a difference method. For these two methods, as well as other methods that can be used within the scope of this invention, the following is performed: Figure 5 The calibration process illustrated in the diagram is to determine the coupling matrix K, which links the phase currents I1, I2, I3 flowing in the primary conductor with the magnetic fields B1, B2, B3, B4 detected by magnetic field detectors 4a, 4b, 4c, 4d (ASIC1, ASIC2, ASIC3, ASIC4). The coupling matrix can be a rectangular matrix with n×n+1 coefficients, where n is the number of phases to be measured and n+1 is the number of magnetic field detectors.

[0073] The pseudo-inverse method can advantageously perform calculations using the known Moore-Penrose inverse, which is useful for inverting non-invertible matrices including rectangular matrices. This method uses the pseudo-inverse matrix K of the coupling matrix K of the magnetic field {B1, B2, B3, B4} discovered by magnetic field detectors ASIC1, ASIC2, ASIC3, and ASIC4. + It should be noted that this method is expressed as the actual magnetic flux density measured by the ASIC, and it can also be expressed as the output signal of the ASIC (which can be a voltage signal V1, V2, V3, V4, or a current signal, which may or may not include the offset in the signal).

[0074]

[0075]

[0076] Therefore, K + It is represented as follows.

[0077] K + = t K(K t K) -1

[0078] This method enables the direct discovery of a unique matrix that links I and B, thereby allowing the coupling matrix to be determined during a calibration process, preferably performed during or after sensor fabrication, before the sensor performs current measurement operations when connected to the electrical system circuitry.

[0079] According to an advantageous aspect of the invention, the coupling matrix can be stored in the non-volatile memory of circuit 5 or in one or more non-volatile memories of the ASIC. Therefore, the sensor contains information about the coupling matrix. In a first embodiment, in the case of an embodiment including a signal processing circuit with a calculation unit configured to output current measurements, the information about the coupling matrix can be used to calculate the current measurements within the sensor.

[0080] In another embodiment, information about the coupling matrix stored in the sensor can be sent to circuitry of an electrical system (not shown) to which the sensor is connected, in which the current measurement value is processed.

[0081] In another embodiment, information about the coupling matrix can be stored in the circuitry of an electrical system external to the sensor, with the coupling matrix dedicated to the sensor and loaded into the memory of the circuitry after a calibration process is performed on the sensor.

[0082] The value of the coupling matrix, determined during the calibration process for each sensor or each batch of sensors, prior to using the sensor for current measurement in the electrical system to which it is connected, advantageously provides a matrix value adjusted for each sensor or sensor batch. Therefore, the matrix value takes into account the manufacturing and material tolerances and variations of each sensor, thus providing an accurate measurement value for each sensor when used to measure current in an electrical system.

[0083] In most cases, the external magnetic field generates essentially the same flux along the central air gap between the core components 3a and 3b. In this case, for example, the influence of this field can be eliminated in the current measurement using the following method. The principle is to perform differential measurements for each current, where the coupling matrix K′ for the differential measurement can be determined using the same calibration method as described above (although V1, V2, V3, V4 are used instead in the following formula as the output voltage signals of the ASIC representing the measured magnetic inductions B1, B2, B3, B4).

[0084]

[0085] Since K′ is square, it is therefore reversible, and the current can be estimated as follows:

[0086]

[0087] The advantages of this method are:

[0088] • A squared K′ matrix (calculated more easily)

[0089] • Perform differential measurements on each current (to eliminate the influence of external fields on the measurement results).

[0090] After analyzing the differential coupling matrix K′, the coefficients representing the output of the ASIC closest to the phase conductor are significantly higher than those of other ASICs located further away from the phase conductor—for example, approximately 1000 times higher. This means that using the two closest ASICs surrounding the phase conductor is sufficient to perform differential measurements, and other ASICs are not necessary for good measurements. In other words, the coupling coefficients from the more distant ASICs can be ignored in terms of the coupling coefficients from the nearest ASIC.

[0091] Therefore, the problem can be simplified by using only the following three coefficients:

[0092] I1≈k 11 '.(V4-V3)I2≈k 22 '.(V3-V2)I3≈k 33 '.(V2-V1)

[0093]

[0094] To provide measurement redundancy and detect faults in the magnetic field detector 4, n of the n+1 magnetic field detectors for an n-phase system (e.g., three of the four magnetic field detectors (for a three-phase system) in this example) can be used to define n+1 new degraded mode matrices (i.e., four in this example), which can then be used to estimate the phase current in another mode (referred to herein as the degraded mode).

[0095] K 123 K 124 K 134 K 234

[0096] in

[0097] The n+1 new reduced-order mode matrix K abc It can be a square matrix of n×n coefficients, where n is the number of phases to be measured and n+1 is the number of magnetic field detectors.

[0098] Because each reduced-order coupling matrix K abc Since it's a square matrix, we can directly invert it. Current matrix I abc While it doesn't provide a precise estimate of the current, it allows for the detection of faults in the magnetic field detector. Reduced-order mode coupling matrix K abc Composed of n rows (Moore Penrose K matrix):

[0099]

[0100]

[0101]

[0102] If the magnetic field detector malfunctions, the error will affect the calculated values ​​of specific phase currents I1, I2, or I3, depending on which reduced-order mode coupling matrix is ​​used. Therefore, by comparing these calculated phase currents I1, I2, or I3 with the reduced-order mode coupling matrix, the origin of the fault can be determined. Furthermore, this method enables the detection of leakage current. The following description... Figure 6 The security analysis method illustrated in the diagram:

[0103] 1. Using the reduced-order mode coupling matrix K 123 K 124 K 134 K 234 K Pseudo and K Diff Estimate phase currents I1I2I3

[0104] 2. Obtain the sum of the three-phase currents for each matrix.

[0105] 3. If the sum of all these (S1) is zero,

[0106]

[0107] Then there shouldn't be any problem.

[0108] 4. If all these sums (S2) have the same value,

[0109]

[0110] Therefore, there exists a leakage current with the value stated in the system being measured.

[0111] 5. If one or both of these sums (S3) are zero,

[0112]

[0113] Then the magnetic field detector is faulty, and the reduced-order mode can be used to determine which magnetic field detector is faulty.

[0114] 5.1 If from K 123 The sum of the currents is zero (S4).

[0115] Then the magnetic field detector ASIC4 is faulty, and only the reduced-order mode matrix needs to be used, because the matrix does not use the faulty ASIC to calculate the current.

[0116] 5.2 If from K 234 The sum of the currents is zero (S5).

[0117] So the magnetic field detector ASIC1 is faulty, and only this matrix is ​​needed.

[0118] 5.3 If from K 124 and K 134 The sum of the currents is zero (S6).

[0119]

[0120] Then any fault in either ASIC2 or ASIC3 of the magnetic field detector

[0121] 5.3.1 For low current (<300A), I2 can be estimated as follows: (I2) Deg =K Deg (B1-B4) where K Deg The constants determined during calibration

[0122] 5.3.2 If (I2) 124 (I2) Deg The absolute error is less than (I²). 134 If the magnetic field detector ASIC3 malfunctions, then the coupling matrix K needs to be used. 124 Otherwise, the magnetic field detector ASIC2 malfunctions and the coupling matrix K needs to be used. 134 (S7)

[0123]

[0124] To improve safety, rapid detection of electrical faults is required; however, estimating current takes too much time. To achieve faster detection, a feature such as... can be implemented in the signal processing circuit. Figure 8 The comparator illustrated in the diagram generates control signals, such as a turn-off signal at a specific voltage threshold. When a high current is flowing in the current sensor, each current can be roughly estimated using only the magnetic field detector closest to the corresponding primary conductor. Therefore, a voltage threshold can be determined for each magnetic field detector to generate a shutdown control signal for an externally controlled system in the event of an electrical fault or overcurrent.

[0125] For example, when I1 is high (with a relative error of 5 to 10%), I1 ≈ k1.V4; if the maximum current of the external system is turned off... ,therefore

[0126] The current sensor according to embodiments of the invention advantageously enables the provision of compact and simple multiphase current sensors (e.g., three-phase current sensors).

[0127] The signal processing circuit of the sensor or the signal processing circuit connected to the external circuit of the current sensor can be advantageously configured with at least two calculation methods to accurately estimate the current: it can advantageously include the pseudo-inverse method and the differential method.

[0128] The signal processing circuitry of the sensor or the signal processing circuitry connected to the external circuitry of the current sensor may advantageously include reduced-order mode calculations to estimate the current that enables the detection of faults, leakage currents, or overcurrents in the magnetic field detector.

[0129] List of reference symbols used

[0130] Current measurement system

[0131] Current sensor 1

[0132] Casing 2

[0133] housing components

[0134] Base 2a

[0135] Cover 2b

[0136] Latch element 12

[0137] Channel 11 for primary conductor

[0138] Install lug 14

[0139] Magnetic core 3

[0140] First core component 3a and second core component 3b

[0141] Magnetic field detectors 4, 4a, 4b, 4c, 4d, 4e, 4f

[0142] ASIC

[0143] ASIC1, ASIC2, ASIC3, ASIC4

[0144] Hall effect detector

[0145] Circuit 5

[0146] Circuit Board 7

[0147] Contact portion for detector 16

[0148] Circuit traces

[0149] Contact portion for connector 18

[0150] Connector 8

[0151] Primary conductor 6

[0152] Phase conductors 6a, 6b, 6c

[0153] Computing unit

Claims

1. A current measurement system, The current measurement system includes a multiphase open-loop current sensor for measuring n phase currents (I1, I2, I3) flowing in multiple, i.e., n primary conductors of a multiphase electrical system. The sensor includes: The housing (2); the magnetic core (3), including a first magnetic core component (3a) and a second magnetic core component (3b); and a plurality of, i.e., n+1, magnetic field detectors (4), mounted in the housing (2) between the first magnetic core component and the second magnetic core component in the portion of the housing that traverses the current sensor of the primary conductor. The system further includes a non-volatile memory and a computing unit. The non-volatile memory stores information about at least one coupling matrix (K) of predefined size [n+1] × n during calibration. This coupling matrix (K) links the phase currents (I1, I2, I3) flowing in the primary conductor with the magnetic induction fields (B1, B2, B3, B4) detected by the magnetic field detectors. The computing unit is configured to use the coupling matrix to calculate the values ​​of the n phase currents from the outputs of the n+1 magnetic field detectors. The computing unit is characterized in that it is further configured to estimate the n phase currents in a reduced-order mode redundancy using n+1 reduced-order mode coupling matrices, each having a size of n×n, based on the output of a subset of the n+1 magnetic field detectors, wherein all n phase currents are considered for each magnetic field detected by the subset of magnetic field detectors, and the computing unit is further configured to detect faults, leakage currents, or overcurrents in the magnetic field detectors based on the redundantly estimated n phase currents.

2. The current measurement system according to claim 1, wherein, The non-volatile memory storing information about at least one coupling matrix (K) is disposed in at least one application-specific integrated circuit (ASIC) forming at least one of the magnetic field detectors, or disposed in the memory of the circuit (5) of the sensor.

3. The current measurement system according to claim 2, wherein, The non-volatile memory storing information about at least one coupling matrix (K) is readable via an external circuit through the connector (8) of the current sensor to transmit the information about the at least one coupling matrix to the external circuit and to calculate the value of the phase current in the external circuit.

4. The current measurement system according to claim 1, wherein, The non-volatile memory storing information about at least one coupling matrix (K) is arranged in the electrical system outside the sensor.

5. The current measurement system of claim 1, further comprising a calculation unit configured to perform at least two different calculation methods to estimate the current, the at least two different calculation methods including a pseudo-inverse method and a differential method.

6. The current measurement system according to claim 1, wherein, The first magnetic core component and the second magnetic core component are in the form of substantially straight rectangular strips formed by stacking laminated soft magnetic material sheets.

7. The current measurement system according to claim 1, wherein, Each of the magnetic core components is received in a corresponding housing component (2a, 2b) of the housing (2), the housing component being formed as a separate component and assembled together, one of the housing components (2a) accommodating the plurality of magnetic field detectors, and the primary conductor portion extending through the housing.

8. The current measurement system according to claim 7, wherein, The channel (11) through which the primary conductor extends is formed by a recess or through cavity in one (2a) of the housing component, and the other housing component (2b) has a substantially flat mating surface.

9. The current measurement system according to claim 1, wherein, The sensor includes a circuit board (7) arranged in a plane substantially orthogonal to the plane (P) in which the air gap between the magnetic core components is formed, along the side of the housing that overlaps with the connection terminal of the magnetic field detector.

10. The current measurement system according to claim 9, wherein, The magnetic field detector is pre-assembled to the circuit board during manufacturing, whereby during the assembly of the circuit board against the base component of the housing, the magnetic field detector is inserted into a cavity (13) in the base component of the housing for receiving the magnetic field detector, the cavity including cavities (13a, 13d) located on either side of the primary conductor and cavities (13b, 13c) between adjacent primary conductors.

11. The current measurement system according to claim 1, wherein, The sensor is used in a three-phase electrical system and includes four magnetic field detectors (4a, 4b, 4c, 4d). Two of the four magnetic field detectors (4a, 4d) are arranged outside three primary conductors (6a, 6b, 6c), while each of the other two of the four magnetic field detectors (4b, 4c) is arranged between corresponding adjacent primary conductors (6a, 6b; 6b, 6c).

12. The current measurement system according to claim 1, wherein, The magnetic field detector is in the form of an ASIC.

13. The current measurement system of claim 1, wherein the current measurement system includes a comparator connected to each magnetic field detector and configured to generate a control signal at a specific voltage threshold determined for each magnetic field detector to generate a shutdown control signal for the electrical system controlled by the current in the event of an electrical fault or overcurrent.

14. A method for measuring multiple currents (I1, I2, I3) flowing in multiple, i.e., n, primary conductors of a multiphase electrical system, the method comprising: - Provide a current measurement system, the current measurement system including a sensor, the sensor including: a housing (2); a magnetic core (3) including a first magnetic core component (3a) and a second magnetic core component (3b); and a plurality of, i.e., n+1, magnetic field detectors (4) installed in the housing (2) between the first magnetic core component and the second magnetic core component in the portion of the housing that traverses the primary conductor of the sensor, the sensor being connected to the circuit of the multiphase electrical system; - Before operating the sensor for measuring the n phase currents flowing in the primary conductor, a calibration method is performed to calculate at least one coupling matrix (K) of size [n+1] × n, which links the phase currents (I1, I2, I3) flowing in the primary conductor with the magnetic induction fields (B1, B2, B3, B4) detected by the magnetic field detector. - Store the at least one coupling matrix in the non-volatile memory of the sensor or the non-volatile memory of the circuit of the multiphase electrical system; - During the operation of the sensor used to measure the phase current flowing in the primary conductor, in the calculation unit of the current measurement system, the values ​​of the n phase currents are calculated using the measurement outputs of the n+1 magnetic field detectors with the at least one coupling matrix; - In the computing unit, n+1 reduced-order mode coupling matrices of size n×n are used to calculate redundant measurements of the plurality of currents (I1, I2, I3) to detect faults in the magnetic field detectors. For an n-phase system, n of the n+1 magnetic field detectors are used to calculate the n+1 reduced-order mode coupling matrices, wherein for each magnetic field detected by the magnetic field detectors, all n phase currents are considered.

15. The method according to claim 14, wherein, The computational unit of the current measurement system performs differential measurements on the current of each phase, wherein the calibration method is used to determine the coupling matrix for the differential measurements. .

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