Current sensor

Abstract

A current sensor (1) comprises: a magnetic field sensor (3); and a T-shaped ferromagnetic structure (2) having an air gap (5). The current sensor (1) is intended to be arranged in a recess (40) of a busbar (4). The T-shaped ferromagnetic structure (2) may comprise two L-shaped ferromagnetic elements (20).

Description

Technical Field

[0001] The invention relates to a current sensor for measuring the intensity of a current in an electrical conductor. Background Art

[0002] Current sensors themselves have a wide range of applications. One of the many areas of application is electric drive systems, such as those used in motor vehicles, though the present invention is not intended to be limited to this area. In electric drive systems, current sensors can be used between power electronics units and electric motors or within power electronics units; for example, they can measure DC current at the input of a power electronics unit or monitor the status of a battery system.

[0003] Known current sensors have many disadvantages; in particular, they are often cumbersome to assemble, both during initial installation and during replacement. Current sensors with a toroidal core are known, for example, from international patent applications WO 2013 / 008205 A2 and WO 2015 / 140129 A1. The electrical conductor passes through the toroidal core and is therefore surrounded by it. During assembly, the conductor must be guided through the toroidal core before further installation. A change or subsequent installation of such a current sensor requires at least partial disassembly of the conductor. In another method, known, for example, from international application WO 2017 / 130437 A1, the magnetic element is mounted from one side of the conductor and the sensor chip, including the evaluation electronics, is mounted from the opposite side of the conductor. In this case, the conductor does not need to be guided through the sensor, but must be accessible on both sides. Furthermore, various approaches are known, such as those described in International Applications WO 2016 / 190087 A1 and WO 2016 / 125638 A1, in which the current sensor already includes a section of an electrical conductor. However, this section must then be connected to other conductors to form a path in which the current intensity is to be measured. Other approaches, such as those disclosed in International Applications WO 2017 / 187809 A1, WO 2018 / 116852 A1, and WO 2013 / 172109 A1, all use a large number of sensor elements on a carrier, some of which have several electrical conductors. These approaches require several sensor elements to measure current intensity, which results in high costs and complex assembly. Summary of the Invention

[0004] It is an object of the present invention to provide a current sensor which does not have at least some of the above mentioned disadvantages.In particular, the current sensor should be easy to assemble and replace.

[0005] This object is achieved by a current sensor according to claim 1. The dependent claims contain advantageous further developments. Claim 9 relates to an electrical system having such a current sensor.

[0006] A current sensor for measuring the current intensity in an electrical conductor according to the present invention includes a magnetic field sensor that determines the current intensity by measuring a magnetic field. According to the present invention, the current sensor has a T-shaped ferromagnetic structure. An air gap is formed between the interfaces of the ferromagnetic structure. In this context, the interface of the ferromagnetic structure refers to the surface of a component of the ferromagnetic structure or a partial region of the surface of a component of the ferromagnetic structure.

[0007] Corresponding to the T-shape of the ferromagnetic structure, the structure has a region forming the main bar of the T and a region forming the crossbar of the T. The current sensor is designed to be inserted, along with the main bar, into a recess in an electrical conductor, such as a busbar. A portion of the conductor then extends on both sides of the main bar. This allows the current sensor to be deployed after the conductor is installed and replaced without partially disassembling the conductor. In this regard, it is sufficient for the current sensor to be accessible from one side of the conductor.

[0008] Preferably, the ferromagnetic structure consists of a laminated core, such as silicon steel, which reduces eddy current losses in the ferromagnetic structure.

[0009] In one embodiment, a T-shaped ferromagnetic structure comprises two L-shaped ferromagnetic elements. In this respect, at least a portion of the main bar of the T is formed by a total of two parallel legs of the two ferromagnetic elements, while the remaining two legs form the crossbar. In particular, the two ferromagnetic elements can have the same shape and size and then be arranged in a mirror-symmetrical manner relative to each other in the T-shaped structure. However, embodiments are also possible in which the two ferromagnetic elements differ in shape and / or size; such embodiments enable a better differential assessment of the magnetic flux density.

[0010] In a further development, the air gap is delimited on both sides by a leg of one of the L-shaped ferromagnetic elements, more precisely by a leg belonging to the main rod of the T.

[0011] In one embodiment, the T-shaped structure has at least one ferromagnetic terminal element. The at least one terminal element forms part of the main bar of the T. In another embodiment, the air gap is bounded on one side by the at least one terminal element. The at least one terminal element can be designed in particular in the form of a plate or disk.

[0012] The T-shaped structure can also have two L-shaped ferromagnetic elements and one or more ferromagnetic terminal elements. In particular, two terminal elements can be provided, one for each L-shaped element. In this arrangement, two intersecting air gaps can exist in the current sensor, bounded on the one hand by the L-shaped elements and on the other hand by the terminal elements.

[0013] Depending on the embodiment, the magnetic field sensor can be arranged inside the air gap or outside the air gap. In the case where the magnetic field sensor is located outside the air gap, it is obvious to a person skilled in the art that the magnetic field sensor must still be located in the vicinity of the T-shaped ferromagnetic structure so that the magnetic field caused by the current flow in the electrical conductor can still be reliably measured, and ultimately the current intensity in the electrical conductor can be reliably measured. Known measurement concepts can be used for the magnetic field sensor; for example, without limiting the present invention, the magnetic field sensor can be a sensor based on the Hall effect or a magnetoresistive effect, such as the giant magnetoresistive (GMR) effect.

[0014] In one embodiment, the magnetic field sensor is electrically conductively connected to a circuit board. Circuitry on the circuit board can be configured to control and read the magnetic field sensor. The circuit board can be arranged in various ways within the current sensor, and depending on this and the placement of the magnetic field sensor, electrical connectors, such as multiple pins, can be oriented between the magnetic field sensor and the circuit board. However, in principle, it is also conceivable to connect the magnetic field sensor directly to a higher-level system that is independent of the current sensor for control and reading purposes.

[0015] In one embodiment, the current sensor is enclosed in a housing. Preferably, the housing is designed in such a way that the current sensor can be inserted together with the housing into a corresponding recess in the electrical conductor. In particular, the housing itself can be T-shaped or also cross-shaped. If a housing is present, it can also surround the above-mentioned circuit board. In a special further development, only one or more connectors for connecting the circuit board to a higher-level system are accessible from the outside of the housing. For example, the connector can include one or more connecting pins or one or more connectors. The housing can be manufactured in any known manner; for example, without limiting the invention, the other components of the current sensor can be overmolded using a plastic material.

[0016] The electrical system according to the invention has an electrical conductor and is characterized by a current sensor as described above for measuring the current intensity in the electrical conductor of the electrical system. A recess is provided in the electrical conductor for inserting the current sensor into it. More precisely, the main rod of a T-shaped structure, which may be the main rod of a T-shaped or cross-shaped housing of the current sensor, is to be inserted into the recess. In principle, the recess can have any shape, such as rectangular, circular, or oval; the cross-section of the region of the current sensor to be inserted into the recess is preferably adapted to the shape of the recess, as this provides good mechanical stability for the arrangement. The recess for the current sensor in the electrical conductor can also be designed asymmetrically. When a current flows through the electrical conductor, this leads to an asymmetry in the magnetic flux density, which can sometimes be advantageous with regard to the frequency response. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The invention and its advantages are explained in more detail below with reference to the accompanying schematic drawings.

[0018] Figure 1 A current sensor according to the invention inserted into a busbar is shown.

[0019] Figure 2 A current sensor according to the invention inserted into a busbar is shown.

[0020] Figure 3 A current sensor according to the invention inserted into a busbar is shown.

[0021] Figure 4 A busbar is shown, into which a current sensor according to the invention can be inserted.

[0022] Figure 5 A further busbar is shown, into which a current sensor according to the invention can be inserted.

[0023] Figure 6 A perspective view of a current sensor according to the invention inserted into a busbar is shown.

[0024] Figure 7 A current sensor according to the invention inserted into a busbar is shown.

[0025] Figure 8 A perspective view of a current sensor according to the invention inserted into a busbar is shown.

[0026] Figure 9 A current sensor according to the invention inserted into a busbar is shown.

[0027] Figure 10 A perspective view of a current sensor according to the invention inserted into a busbar is shown.

[0028] Figure 11A perspective view of a current sensor according to the invention inserted into a busbar is shown.

[0029] Figure 12 A current sensor according to the invention is shown with a housing, which is inserted into a busbar.

[0030] Figure 13 A current sensor according to the invention is shown with a housing, which is inserted into a busbar.

[0031] Figure 14 A side view of a current sensor according to the invention with a housing inserted into a busbar is shown.

[0032] Figure 15 A side view of a current sensor according to the invention with a housing inserted into a busbar is shown.

[0033] Figure 16 A side view of a current sensor 1 according to the invention is shown with a housing, inserted into a busbar.

[0034] The drawings represent only exemplary embodiments of the invention and should in no way be interpreted as limiting the invention to the exemplary embodiments shown. DETAILED DESCRIPTION

[0035] Figure 1 An embodiment of a current sensor 1 according to the present invention is shown inserted into a busbar 4, which in this example forms an electrical conductor. The illustration is a cross-sectional view, allowing for visibility of two portions of the busbar 4 on either side of a recess in the busbar 4 for the current sensor 1. The current sensor 1 comprises a T-shaped ferromagnetic structure 2. In the illustrated embodiment, the T-shaped ferromagnetic structure comprises two L-shaped ferromagnetic elements 20 and two ferromagnetic terminal elements 23, one for each L-shaped element 20. Each L-shaped element 20 comprises a first leg 21 and a second leg 22. In the illustrated example, the first leg 21 and the terminal element 23 together form the main leg of the T-shaped structure 2, while the second leg 22 together form the crossbar of the T-shaped structure 2. In the illustrated embodiment, the first leg 21 and the terminal element 23 define an air gap 51 and an air gap 52. The air gaps 51 and 52 intersect.

[0036] Magnetic field sensor 3 is arranged in air gap 51 to determine the current intensity in busbar 4 by measuring the magnetic field. Examples of possible alternative positions 31 and 32 for the magnetic field sensor are shown with dashed lines. Such alternative positions are also generally possible for the other embodiments shown. A person skilled in the art will select the position and orientation of the magnetic field sensor based on known magnetic field sensor types and the specific installation situation of the current sensor.

[0037] Figure 2 Another embodiment of the current sensor 1 according to the present invention, which is inserted into a busbar 4, is shown. Figure 1 The embodiment shown is similar, and the elements shown have been described. Figure 1 In contrast to the illustrated embodiment, the T-shaped structure 2 lacks the terminal element 23. The main stem of the T is formed by the first leg 21 of the L-shaped ferromagnetic element 20, which delimits the air gap 5 on both sides. Since the terminal element 23 is absent, there is no second air gap. A magnetic field sensor 3 is arranged in the air gap 5. Alternative locations for the magnetic field sensor are not shown.

[0038] Figure 3 Another embodiment of a current sensor 1 according to the invention is shown, which is inserted into a busbar 4. In this embodiment, a T-shaped ferromagnetic structure 2 comprises a ferromagnetic main portion 25 and a ferromagnetic terminal element 23; the main portion 25 and the terminal element 23 delimit an air gap 5. A magnetic field sensor 3 is arranged in the air gap 5.

[0039] Figure 4 A busbar 4 is shown with a recess 40, here of rectangular shape, into which a current sensor 1 according to the invention can be inserted. The direction 100 of the current through the busbar 4 is also shown.

[0040] Figure 5 A busbar 4 is shown with a recess 40, here oval in shape, into which a current sensor 1 according to the invention can be inserted. The direction 100 of the current through the busbar 4 is also shown.

[0041] Figure 6 A perspective view of a current sensor 1 according to the invention inserted into a busbar 4 is shown. More precisely, the main rod of the T-shaped ferromagnetic structure 2 is inserted into a recess 40 in the busbar 4. The configuration of the current sensor 1 corresponds to Figure 2 The configuration shown. Accordingly, the T-shaped structure 2 is formed by two ferromagnetic elements 20, which delimit an air gap 5 on both sides. A magnetic field sensor 3 is shown in this air gap, along with connection pins 33 for the magnetic field sensor. Furthermore, the direction 100 of the current through the busbar 4 is shown.

[0042] Figure 7 The present invention shows Figure 2 The current sensor 1 is similar to the one shown and is inserted into the busbar 4. Figure 2 In addition to the elements described, the current sensor 1 here comprises a circuit board 7 for controlling and reading the magnetic field sensor 3. The magnetic field sensor 3 is connected to the circuit board 7 via connection pins 33. The circuit board 7 has one or more connection pins 71 for connecting the circuit board 7 to a higher-level system.

[0043] Figure 8 A perspective view of a current sensor 1 according to the invention inserted into a busbar 4 is shown. Figure 7 The embodiment shown corresponds to the embodiment shown. Figure 7 All shown elements of the current sensor 1 are discussed. Furthermore, the direction 100 of the current through the busbar 4 is shown.

[0044] Figure 9 The present invention shows Figure 1 The current sensor 1 is similar to the one shown and is inserted into the busbar 4. Figure 1 In addition to the elements described, the current sensor 1 here comprises a circuit board 7 for controlling and reading the magnetic field sensor 3. The circuit board 7 has one or more connection pins 71 for connecting the circuit board 7 to a higher-level system. Apart from the configuration of the T-shaped ferromagnetic structure 2, the embodiment shown here is similar to Figure 7 The embodiment shown differs in the different arrangement of the printed circuit board 7 relative to the other components of the current sensor 1. Here, too, the printed circuit board 7 is partially inserted into a recess in the busbar 4.

[0045] Figure 10 A perspective view of a current sensor 1 according to the invention inserted into a busbar 4 is shown, with Figure 8 The implementation shown here is similar to Figure 8 The embodiment shown differs in the arrangement of the circuit board 7, which is connected to the magnetic field sensor 3 via the connection pins 33. The arrangement of the circuit board corresponds to Figure 9 Here, too, the circuit board 7 is partially inserted into the recess 40 in the busbar 4 .

[0046] Figure 11 A perspective view of a current sensor 1 according to the invention inserted into a busbar 4 is shown. This illustration corresponds largely to Figure 9 A perspective view of the embodiment shown. Figure 11 Only for Figure 9 Magnetic field sensor 3 in FIG. 3 shows alternative positions 31 , 32 . Furthermore, direction 100 of the current through busbar 4 is shown.

[0047] Figure 12 An embodiment of a current sensor 1 according to the invention is shown, which corresponds largely to Figure 7 In addition to the embodiment shown Figure 7In addition to the embodiment shown, the current sensor 1 is enclosed in a housing 8. Only the connection pins 71 for connecting the circuit board 7 to a higher-level system are accessible from the outside of the housing 8. The housing 8 is also T-shaped here, and the main rod of the T is inserted into the recess in the busbar 4. For the other elements shown, refer to Figure 7 Description.

[0048] Figure 13 A current sensor 1 according to the invention is shown, which corresponds largely to Figure 9 The embodiment shown, except for the alternative position of the magnetic field sensor 3. Figure 9 In addition to the embodiment shown, the current sensor 1 is enclosed in a housing 8. Only the connection pins 71 for connecting the circuit board 7 to a higher-level system are accessible from the outside of the housing 8. The housing 8 is cross-shaped here, and the main rods are inserted into the recesses in the busbar 4. For the other elements shown, refer to Figure 9 Description.

[0049] Figure 14 A side view of a current sensor 1 according to the invention with a housing 8 is shown. The housing 8 is inserted into a busbar 4. The L-shaped ferromagnetic element 20 of the current sensor 1 and the connection pins 33 of the magnetic field sensor, which are concealed here, for connecting the magnetic field sensor to a circuit board 7 are shown. Only the connection pins 71 for connecting the circuit board 7 to a higher-level system are accessible from outside the housing 8. Furthermore, the direction 100 of the current through the busbar 4 is shown.

[0050] Figure 15 FIG. 1 shows a side view of a current sensor 1 having a housing 8 according to the present invention. Figure 14 The embodiment shown differs primarily in the arrangement of the circuit board 7 .

[0051] Figure 16 A side view of a current sensor 1 according to the present invention with a housing 8 is shown. Here, the current sensor 1, together with the housing 8, is inserted into a busbar 4, which has an angled profile. Also shown with the current sensor 1 is a circuit board 7 and connection pins 33 for connecting the circuit board 7 to a magnetic field sensor. The magnetic field sensor is covered by one of the L-shaped ferromagnetic elements 20. The circuit board 7 is connected to a higher-level circuit board 300 via connection pins 71.

[0052] Description of Reference Numerals

[0053] 1 Current sensor 2 T-shaped ferromagnetic structure 3 Magnetic field sensor 4 Electrical conductor (busbar) 5 Air gap 7 Circuit board 8 Housing 20 L-shaped ferromagnetic element 21 First leg 22 Second leg 23 Ferromagnetic terminal element 25 Main part (main part of T-shaped structure) 31 Alternative position (current sensor) 32 Alternative position (current sensor) 33 Connecting pin 40 Recess (in busbar) 51 Air gap 52 Air gap 71 Connecting pin 100 Current direction 300 Higher-level circuit board

Claims

1. A current sensor (1) for measuring the intensity of a current in an electrical conductor (4), the current sensor (1) comprising: Magnetic field sensor (3), The current sensor (1) is characterized in that A T-shaped ferromagnetic structure (2) having an air gap (5) between interfaces of the ferromagnetic structure (2); the T-shaped ferromagnetic structure (2) comprises two L-shaped ferromagnetic elements (20) and at least one ferromagnetic terminal element (23), each L-shaped ferromagnetic element (20) having a first leg (21) and a second leg (22), the first leg (21) and the ferromagnetic terminal element (23) together forming a main rod of the T-shaped ferromagnetic structure (2), and the second leg (22) together forming a crossbar of the T-shaped ferromagnetic structure (2), the first leg (21) and the ferromagnetic terminal element (23) defining a first air gap (51) and a second air gap (52) intersecting each other.

2. The current sensor (1) according to claim 1, wherein The magnetic field sensor (3) is arranged inside the air gap (5) or outside the air gap (5).

3. The current sensor (1) according to claim 1, wherein The magnetic field sensor (3) is connected to the circuit board (7) in an electrically conductive manner.

4. The current sensor (1) according to any one of the preceding claims, wherein The current sensor (1) is encapsulated in a T-shaped or cross-shaped housing.

5. An electrical system having an electrical conductor (4), characterized in that A current sensor (1) for measuring the current intensity in an electrical conductor (4) of an electrical system according to any one of claims 1 to 4, wherein the electrical conductor (4) has a recess (40) into which the current sensor (1) is inserted.

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