Current sensor with primary conductor

Abstract

Current sensor (1) comprising a primary conductor arrangement (2) comprising a primary conductor (3) and a sensor unit (10) mounted on the primary conductor arrangement, wherein the sensor unit comprises an insulating body (20) and at least one magnetic field sensor element (12) which is rigidly attached to or in the insulating body, wherein the magnetic field sensor serves to detect a magnetic field generated by a current flowing in the primary conductor (3), wherein the sensor unit (10) further comprises at least one mounting element (30, 30') which is rigidly attached to the insulating body (20), wherein the current sensor (1) comprises a weld (9) which attaches the mounting element (30, 30') of the sensor unit (10) to the primary conductor assembly (2).

Description

[0001] The present invention relates to a current sensor comprising a primary conductor and a magnetic field sensor for detecting a magnetic field generated by a current flowing in the primary conductor.

[0002] For a reliable measurement of the magnetic field generated by a current flowing in the primary conductor, it is essential that the positions of the magnetic field sensor elements relative to the primary conductor are fixed. Any change in the position of the magnetic field sensor elements relative to the primary conductor leads to a change in the output signal and thus to a systematic error.

[0003] In light of the foregoing, one object of the invention is to provide a current sensor with an integrated primary conductor that is reliable and accurate.

[0004] It is advantageous to provide a current sensor with an integrated primary conductor, the manufacture of which is economical.

[0005] It is advantageous to provide a current sensor with an integrated primary conductor that is robust and durable.

[0006] It is advantageous to provide a current sensor with an integrated primary conductor that is compact.

[0007] The objectives of the invention were achieved by providing a current sensor according to claim 1.

[0008] The dependent claims set out various advantageous features of embodiments of the invention.

[0009] Herein lies a current sensor comprising a primary conductor arrangement including a primary conductor and a sensor unit mounted on the primary conductor arrangement, wherein the sensor unit comprises an insulating body and at least one magnetic field sensor element rigidly attached to or in the insulating body, wherein the magnetic field sensor serves to detect a magnetic field generated by a current flowing in the primary conductor.

[0010] The sensor unit further comprises at least one mounting element rigidly attached to the insulating body, whereby the current sensor mounting surface includes a weld seam which attaches the sensor unit to the primary conductor assembly.

[0011] In one embodiment, the current sensor mounting surface is attached directly to the primary conductor through the weld seam.

[0012] In another embodiment, the primary conductor arrangement further comprises an insulating body and at least one mounting surface rigidly attached to the insulating body, wherein the weld connects the at least one mounting element of the sensor unit to the at least one mounting surface of the primary conductor arrangement.

[0013] In one embodiment, the primary conductor and the at least one mounting element of the sensor unit consist of a non-ferromagnetic metal, preferably copper or a copper alloy.

[0014] In one embodiment, the primary conductor, the at least one mounting element of the sensor unit and the at least one mounting surface consist of a non-ferromagnetic metal, preferably copper or a copper alloy.

[0015] In some embodiments, the weld seam is obtained by laser welding, electron beam welding, or ultrasonic welding.

[0016] In an advantageous embodiment, the primary conductor is a rectangular profiled busbar.

[0017] In an advantageous embodiment, the at least one magnetic field sensor element is arranged on a measuring section of the primary conductor and the primary conductor comprises a structure for increasing a gradient of the magnetic field generated by the current flowing in the primary conductor in the measuring section.

[0018] In an advantageous embodiment, a width W m the measuring section is smaller than a total width W totalof the primary conductor.

[0019] In one embodiment, the sensor unit comprises a gradient magnetic field sensor configured to measure a spatial gradient of a magnetic field, or a differential magnetic field sensor configured to measure a difference in the magnetic field between two positions.

[0020] In one embodiment, the sensor unit comprises a Hall sensor and the at least one magnetic field sensor element is at least one Hall element.

[0021] In an advantageous embodiment, the sensor unit comprises an integrated sensor circuit that includes the at least one magnetic field sensor element.

[0022] In an advantageous embodiment, the integrated sensor circuit further comprises one or more signal processing circuits, such as one or more amplifiers and / or one or more analog-to-digital converters.

[0023] In an advantageous embodiment, the insulating body of the sensor unit comprises an insulating substrate, preferably a printed circuit board, and the integrated sensor circuit is mounted on the insulating substrate.

[0024] In an advantageous embodiment, the insulating substrate comprises a lower metallization layer on a lower surface facing the primary conductor and conductor tracks formed in the lower metallization layer and / or an edge metallization, wherein the at least one mounting element is formed in the lower metallization layer at an edge or edges of the insulating substrate and / or in the edge metallization, and the weld seam is formed between the edge or edges or the edge metallization and the primary conductor or the at least one mounting surface of the primary conductor arrangement.

[0025] In an advantageous embodiment, the insulating substrate comprises an upper metallization layer on an upper surface facing away from the primary conductor and conductor tracks formed in the upper metallization layer.

[0026] In an advantageous embodiment, the conductor tracks in the upper metallization layer comprise contact surfaces and the integrated sensor circuit is electrically connected to the contact surfaces.

[0027] In an advantageous embodiment, the sensor unit further comprises sensor connections that are electrically connected to the contact surfaces, wherein the sensor connections include sleeves for press fits.

[0028] In an advantageous embodiment, the sensor unit comprises a shield formed by a conductor track of the upper metallization layer of the insulating substrate, and the integrated sensor circuit is mounted on the shield.

[0029] In an advantageous embodiment, the sensor comprises a plurality of conductors of a conductor frame, and the integrated sensor circuit is mounted on a first conductor of the plurality of conductors.

[0030] In an advantageous embodiment, the sensor unit comprises a shield formed by the first conductor.

[0031] In an advantageous embodiment, at least some of the plurality of conductors form contact surfaces at a first end for electrically connecting the integrated sensor circuit and sensor terminals at a second end.

[0032] In an advantageous embodiment, the insulating body of the sensor unit is obtained by forming, preferably by transfer forming.

[0033] In an advantageous embodiment, at least one of the plurality of conductors is rigidly attached to the insulating body of the sensor unit and electrically isolated from the integrated sensor circuit and forms the at least one mounting element of the sensor unit.

[0034] In an advantageous embodiment, the weld seam is formed at a first end of the at least one mounting element of the sensor unit and a second end of the at least one mounting element of the sensor unit is at least partially embedded in the insulating body of the sensor unit.

[0035] In an advantageous embodiment, the at least one mounting element of the sensor unit comprises a thermal relief structure to increase the thermal resistance from the at least one mounting element of the sensor unit to the insulating body of the sensor unit.

[0036] Further advantageous features of the invention will become apparent from the following detailed description of embodiments of the invention and the accompanying illustrations. Brief description of the characters Fig. Figure 1 is a schematic view of a current sensor according to an embodiment of the invention; Fig. Figure 2 is a schematic view of a current sensor according to an embodiment of the invention; Fig. Figure 3 is a perspective schematic view of a current sensor according to an embodiment of the invention; Fig. Figure 4 is a top view of the current sensor of Fig. 3; Fig. 5 is a side view of the current sensor of Fig. 3; Fig. Figure 6 is a perspective schematic view of a current sensor according to an embodiment of the invention; Fig. Figure 7 is a top view of the current sensor of Fig. 6; Fig. Figure 8 is a side view of the current sensor of Fig. 6.

[0037] Referring to the figures, a current sensor 1 according to embodiments of the invention comprises a primary conductor arrangement 2 and a sensor unit 10 mounted on the primary conductor arrangement.

[0038] According to one aspect of the invention, the sensor unit 10 is rigidly attached to the primary conductor arrangement 2 by a weld 9.

[0039] The primary conductor arrangement 2 comprises a primary conductor 3 and, in certain embodiments, may further comprise an insulating housing 7 and a mounting surface 8, as shown in Fig. 2 illustrated.

[0040] The sensor unit comprises at least one magnetic field sensor element 12 for detecting a magnetic field generated by a current flowing in the primary conductor 3, and an insulating body 20 designed to electrically isolate the at least one magnetic field sensor element 12 from the primary conductor 3.

[0041] The at least one magnetic field sensor element 12 is rigidly attached to the insulating body 20 of the sensor unit 10. The sensor unit 10 further comprises at least one mounting element 30, which is rigidly attached to the insulating body 20 of the sensor unit 10. The at least one mounting element 30 of the sensor unit 10 can be a single element arranged on one side of the sensor unit 10, as shown in the Fig. 1 and Fig.Figure 2 illustrates this. Alternatively, the single element can partially or completely surround the sensor unit 10 (not shown in the figures). In the embodiments of the Fig. 6 to 8 and 3 to 5 two and three elements respectively. The at least one mounting element 30 of the sensor unit 10 can comprise a different number of elements, e.g. four elements (not shown in the figures).

[0042] In preferred embodiments, as in the Fig. As illustrated in Figures 1 and 3 to 8, the current sensor 1 comprises a weld 9 that connects the at least one mounting element 30, 30' of the sensor unit 10 to the primary conductor 3.

[0043] In alternative embodiments, such as in Fig.As illustrated in Figure 2, the primary conductor assembly 2 comprises the primary conductor 3, an insulating body 7, and at least one mounting surface 8. The at least one mounting surface 8 and the primary conductor 3 are rigidly attached to the insulating body 7 of the primary conductor assembly 2. The current sensor 1 comprises a weld 9 that connects the at least one mounting element 30 of the sensor unit 10 to the at least one mounting surface 8 of the primary conductor assembly 2.

[0044] In preferred embodiments, the primary conductor 3 is a busbar. The primary conductor 3 consists of a non-ferromagnetic metal, preferably copper or a copper alloy. The at least one mounting element 30, 30' of the sensor unit 10 also consists of a non-ferromagnetic metal, for example, copper or a copper alloy, preferably the same metal as that of the primary conductor 3. The at least one mounting surface 8 of the primary conductor arrangement 2 also consists of a non-ferromagnetic metal, for example, copper or a copper alloy, preferably the same metal as that of the at least one mounting element 30, 30' of the sensor unit 10.

[0045] The insulating body 7 of the primary conductor arrangement 2 and the insulating body 20 of the sensor unit 10 are rigid, and the at least one mounting surface 8 of the primary conductor arrangement 2 and the at least one mounting element 30, 30' of the sensor unit 10 are shaped and arranged such that the at least one magnetic field sensor element 12 has a fixed position with respect to the primary conductor 3.

[0046] The advantage of weld 9 is that it produces a continuous metal area which, compared to solder, silver sintering paste, adhesives, etc., is less prone to fracture and less affected by surface properties such as cleanliness, impurities, oxidation, and roughness, which make the manufacturing process susceptible to variations in other types of joints.

[0047] In preferred embodiments, the weld seam 9 is obtained by laser welding. The laser welding process can be seamlessly integrated into other laser welding steps in a power electronics assembly process, is fast, dry, requires no curing, heating, etc., and is therefore highly desirable from a sustainability perspective. It requires no additives, which are often characterized by a short shelf life. The laser welding process can be tailored to a small heat-affected zone, such that the heat load beyond the target area is minimal and therefore compatible with the electronics housing.

[0048] In alternative embodiments, the weld seam 9 is obtained by electron beam welding, ultrasonic welding or electrical resistance welding, such as spot welding.

[0049] The at least one magnetic field sensor element 12 is arranged on a measuring section 4 of the primary conductor 2, for example vertically above the primary conductor 2.

[0050] In preferred embodiments, the primary conductor 3 comprises a structure such as a notch, a slot, a meander structure, a constriction or a narrowing to increase a gradient of the magnetic field generated by the current flowing in the primary conductor 3 in the measuring section 4 or to align the magnetic field favorably compared to disturbing gradient fields generated by other sources.

[0051] In the in the Fig. In embodiments 3 to 8 illustrated, the structure includes a narrowing 6, i.e., the measuring section 4 has a smaller width W. m on as a total width W total of the primary conductor 2. This narrowing is created by slots 5 extending from the sides of the busbar 3.

[0052] In a preferred embodiment, the sensor unit 10 is a gradient magnetic field sensor designed to measure a spatial gradient of a magnetic field, or a differential magnetic field sensor designed to measure a difference in the magnetic field between two positions.

[0053] In preferred embodiments, the magnetic field sensor is a Hall sensor and the at least one magnetic field sensor element 12 is at least one Hall element.

[0054] The sensor unit 10 can comprise an integrated sensor circuit 11, which includes at least one magnetic field sensor element 12. The integrated sensor circuit 11 can further comprise one or more signal processing circuits, such as one or more amplifiers and / or one or more analog-to-digital converters.

[0055] In preferred embodiments, the integrated sensor circuit 11 is a single silicon chip.

[0056] The sensor unit 10 is a current transformer for detecting a current flowing in the primary conductor 3 based on at least one signal from the at least one magnetic field sensor element 12. The output signal of the sensor unit 10 can be calibrated. Calibration of the output signal of the sensor unit 10 can be performed in the integrated sensor circuit 11 or in a separate circuit or chip.

[0057] In the Fig. In the illustrated embodiment shown in Figures 3 to 5, the insulating body of the sensor unit 10 comprises an insulating substrate 20a, and the integrated sensor circuit 11 is mounted on the insulating substrate 20a. The insulating substrate 20a can be a printed circuit board, in particular a ceramic printed circuit board. The insulating substrate 20a comprises an upper metallization layer 21 on an upper surface facing away from the primary conductor 3 and conductive traces formed in the upper metallization layer 21.

[0058] The conductive traces in the upper metallization layer 21 comprise contact surfaces 22. The sensor unit 10 further comprises bond wires 13, which electrically connect the integrated sensor circuit 11 to the contact surfaces 22. The contact surfaces 22 are electrically connected to the sensor terminals 26. The sensor terminals 26 comprise sleeves 27 for press fits. The insulating body 20 of the sensor unit 10 may further comprise an encapsulation (not shown in the figures) which at least partially covers the upper surface of the insulating substrate 20a. The encapsulation is designed to provide mechanical stability to the sleeves 27 and / or to electrically insulate the upper metallization layer 21 and the electrical components on the upper surface of the insulating substrate 20a.

[0059] The sensor unit 10 can include a shield 23, 43. The sensor unit 10 of the embodiment of Fig.3 to 5 comprise a shield 23 formed by a conductor track of the upper metallization layer 21 of the insulating substrate 20a. The integrated sensor circuit 11 is mounted on the shield 23.

[0060] The insulating substrate 20a further comprises a lower metallization layer 24 on a lower surface facing the primary conductor 3 and conductor tracks formed in the lower metallization layer 24. In addition, or alternatively to the lower metallization layer 24, the insulating substrate 20a further comprises an edge metallization (not shown in the figures).

[0061] The at least one mounting element 30' is formed in the lower metallization layer 24 at an edge or edges 25 of the insulating substrate 20a and / or in the edge metallization. The edge or edges 25 are accessible for welding. The weld seam 9 is formed between the edge or edges 25 or the edge metallization and the primary conductor 3 or the at least one mounting surface 8 of the primary conductor arrangement 2.

[0062] In the Fig. In the illustrated embodiment shown in Figures 6 to 8, the sensor unit 10 comprises a plurality of conductors 40a-e of a conductor frame 40, and the integrated sensor circuit 11 is mounted on a first conductor 40a of the plurality of conductors. The sensor unit 10 includes a shield 23 formed by the first conductor 40a.

[0063] Three of the multiple conductors 40a, 40b, 40c form contact surfaces 41 at a first end for electrically connecting the integrated sensor circuit 11 and the sensor terminals 42 at a second end. The integrated sensor circuit 11 is electrically connected to the contact surfaces 41 via bond wires 13.

[0064] In the Fig. In the embodiment illustrated in Figures 6 to 8, the insulating body 20 of the sensor unit 10 is obtained by forming, preferably by transfer forming. The insulating body 20 completely surrounds the integrated sensor circuit 11 and the bond wires 13 and partially encapsulates the plurality of lines 40a to e to form a chip package.

[0065] Two of the multiple conductors 40d, 40e are rigidly attached to the insulating body 20 of the sensor unit 10 and are electrically insulated from the integrated sensor circuit 11 and form the mounting elements 30 of the sensor unit 10.

[0066] The weld 9 is formed at a first end 30a of each mounting element 30 of the sensor unit 10, and a second end 30b of each mounting element 30 of the sensor unit 10 is partially embedded in the insulating body 20 of the sensor unit 10. The second end 30b of each mounting element 30 of the sensor unit 10 can include a thermal relief structure 30c to increase the thermal resistance from the mounting element 30 to the chip housing and to reduce the heat load from the weld, while maintaining sufficient mechanical strength and stiffness. List of reference symbols Current sensor 1 Primary conductor arrangement 2 Primary conductor, busbar 3 - total width W total Measuring section 4 Slots 5 Narrowing 6 - Width W m Insulating body 7 Mounting surface 8 Sensor unit 10 Integrated sensor circuit 11 Magnetic field sensor element(s) 12 Bond wires 13 Insulating body 20 Insulating substrate 20a Upper metallization layer 21 Contact surfaces 22 Shielding 23 Lower metallization layer 24 Mounting elements 30' Edge 25 for weld seam Encapsulation (not shown in the figures) 26 sensor connections Sleeves 27 for press fits Insulating body, shape 20 Wiring frame 40 Lines 40a-e 41 contact surfaces 42 sensor connections Shielding 43 Mounting elements 30 End for weld 30a End connected to the insulating body Thermal relief structure 30c Weld 9

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