A device including a receptacle for a C-shaped magnetic core surrounding a conductive strip

Abstract

The present invention relates to an apparatus comprising: a C-shaped magnetic core (5); a conductive strip (1) around which the C-shaped magnetic core (5) is mounted; and a component forming a receiving portion (7) comprising a bottom (8) and sidewalls (9) defining a receiving volume (10) of the receiving portion in which the C-shaped magnetic core (5) is received, the component forming a groove in an air gap (6) of the C-shaped magnetic core (5) adapted to receive a current sensor. The receiving portion (7) includes a centering element for centering the C-shaped magnetic core (5) in a transverse plane parallel to the bottom (8) of the receiving portion. The apparatus comprises resin or adhesive in the receiving portion (7), the C-shaped magnetic core (5) being at least partially embedded in the resin or adhesive. The bottom (8) of the receiving portion (7) includes a support post on which the C-shaped magnetic core (5) is supported. The conductive strip (1) passes through the bottom (8) and is in direct contact with the resin or the adhesive.

Description

Technical Field

[0001] This invention claims priority to French application 2401530, filed on February 16, 2024, the contents of which (text, drawings and claims) are incorporated herein by reference.

[0002] This invention relates to the field of electrical connection between an inverter and a motor controlled by the inverter.

[0003] The present invention relates in particular to components for measuring current in an electrical connection and the assembly of such components.

[0004] The invention is described below in the context of an inverter that supplies power to and controls a traction motor in a motor vehicle, which is a preferred application of the invention. However, the invention is applicable to any assembly including an inverter and a motor powered by the inverter. Background Technology

[0005] Electric or hybrid vehicles are typically equipped with one or more inverters that can generate, in particular, the AC voltage required to operate a synchronous or asynchronous traction motor from a DC voltage source (such as a battery).

[0006] The inverter includes power modules that form a "power stage", the power modules including electronic switches whose opening and closing are appropriately controlled by a control module to supply power to a phase (e.g., three-phase) of the motor.

[0007] The electrical connection between the inverter and the motor (which allows an electrical connection to be established between the power stage of the inverter and the phase of the motor) is usually implemented by means of conductive strips (commonly referred to as "buses").

[0008] In the following text, the term "conductive strip" is used to refer to these busbars, which correspond to thick conductors typically made of copper, used to transmit power with low resistance and minimal loss.

[0009] The important thing is to be able to measure the current flowing through these conductive strips.

[0010] Current measurements are particularly useful for providing feedback to the inverter, allowing for precise adjustment of power output and more effective control of motor speed and torque. Furthermore, the provided current measurements are important for system monitoring and protection. For example, the current measurements can be used to detect potential overloads or faults in the motor.

[0011] It is known to measure the current in a conductive strip using a component that includes a C-shaped magnetic core and a Hall effect sensor.

[0012] The term "C-shaped core" refers to a component made of magnetic material having a "C"-shaped geometry. C-shaped cores are also simply referred to as "C-shaped cores" or "C-cores." These terms are used synonymously throughout the remainder of this document.

[0013] Therefore, to measure the current in the conductive strip, the C-core is used in conjunction with a current sensor (in this case, a Hall effect sensor). The C-core is used to concentrate the magnetic field created by the current passing through the conductive strip, which allows for improved measurement accuracy. Due to the open shape of the C-core, the current sensor can be mounted in the air gap (the open portion of the C-core). The C-core protects the sensor from external magnetic interference, thereby improving the reliability and accuracy of the measurement.

[0014] There are many different types of C-shaped magnetic cores on the market, which differ in the materials used or the manufacturing methods. C-shaped magnetic cores can be, in particular, laminated or wound. Laminated C-shaped magnetic cores consist of multiple layers of insulating magnetic material stacked to form the C-shape of the core, while wound C-shaped magnetic cores are made from a single strip of magnetic material to create a continuous core that is more efficient at high frequencies.

[0015] Depending on the application being considered, the C-core can be held in place in several ways: it can be held in place by resin bonding, by overmolding, or by mechanical fasteners (clamps, screws, etc.).

[0016] When the C-shaped core is of the laminated type, these layers can be mechanically held together and / or surface-treated, for example, using a punch. When the core is wound, it cannot be coated or overmolded and therefore cannot be protected from corrosion. However, untreated wound C-shaped cores can achieve the best magnetic characteristics. However, these cores, typically made of iron-silicon, are very susceptible to corrosion.

[0017] Regardless of the C-core technology considered, it is generally necessary to ensure the mechanical strength, protection, and positioning of the C-core as precisely as possible when it is positioned around the conductive strip. Furthermore, the C-core should be placed as close as possible to the conductive strip.

[0018] For example, document JP2013140140 discloses a generally annular receiving portion for receiving a C-core. The receiving portion includes an outer wall and an inner wall, and includes elements projecting inward from the outer wall of the receiving portion. These elements ensure the centering of the C-core in the transverse plane of the receiving portion. The C-core is fixed with resin, and a conductive strip passes through an opening formed by the inner wall.

[0019] Document US2012032667 relates to a current sensor structure comprising a generally toroidal magnetic core. The magnetic core includes stacked magnetic plates received in an insulating housing and secured to the housing by a molding compound cast into the housing. The structure is configured such that the magnetic core is supported by the front wall of the housing, while leaving a space between the core and the front wall.

[0020] Nevertheless, the proposed assembly can be further improved, in particular to ensure higher efficiency of the current sensor and to guarantee perfect, reproducible positioning and better protection of the C-shaped magnetic core. Furthermore, the C-shaped magnetic core must be easy to implement and industrialize, and, where possible, automatable. Summary of the Invention

[0021] Therefore, the present invention was developed in the above context and tends to improve the assembly of a system including a C-shaped magnetic core and a conductive strip in order to perform the measurement of the current in the conductive strip.

[0022] Therefore, the present invention relates to an apparatus comprising: a C-shaped magnetic core; a conductive strip around which the C-shaped magnetic core is mounted; and a component forming a receiving portion, the receiving portion including a bottom and sidewalls defining a receiving volume of the receiving portion, the C-shaped magnetic core being received in the receiving volume, the component forming recesses in the air gap of the C-shaped magnetic core, the recesses being adapted to receive a current sensor. The receiving portion includes a centering element for centering the C-shaped magnetic core in a transverse plane parallel to the bottom of the receiving portion. The apparatus further includes a hardening resin or adhesive in the receiving portion, the C-shaped magnetic core being at least partially embedded in the hardening resin or adhesive. The bottom of the receiving portion includes plots on which the C-shaped magnetic core is supported. A conductive strip passing through the bottom is in direct contact with the resin or adhesive.

[0023] Therefore, the device proposed in the context of this invention allows the C-shaped core to be positioned and maintained relative to the conductive strip at a precise and reproducible position. Specifically, the distance between the outer edge of the conductive strip and the inner edge of the C-core is preferably substantially constant over the entire circumference of the conductive strip, and can be between 0.5 mm and 3 mm, preferably between 1 mm and 2 mm. This avoids premature saturation of the C-core under high current, allows for better concentration of the magnetic field, and reduces the volume of the C-core. In fact, this distance is a trade-off between mechanical considerations (the distance should be minimized) and electronic considerations (sufficient distance should be provided to ensure electrical insulation). Therefore, the magnetic field created by the current flowing through the strip is perfectly predictable, and current measurements performed by means of a sensor suitable for this position will be highly accurate.

[0024] Furthermore, the support pillar at the bottom of the receiving portion not only ensures the position and alignment of the C-shaped core within the depth of the receiving portion, but also ensures that the liquid resin or adhesive can flow entirely around the C-shaped core in a liquid state. Due to this good fluidity, the risk of air bubbles in the resin or adhesive is limited, and the time required to embed the C-shaped core into the resin or adhesive is reduced. The resin or adhesive absorbs thermal deformation (from the conductive strip and the receiving portion), which affects measurement quality.

[0025] In some embodiments, the core is effectively protected from corrosion by the resin or adhesive because it is completely embedded without air. In some preferred embodiments, a wound C-shaped core can be used.

[0026] Furthermore, since the conductive strip is in direct contact with the resin or adhesive, this means that when the conductive strip passes through the bottom of the receiving portion, the receiving portion does not include the wall surrounding the conductive strip between the conductive strip and the C-shaped magnetic core. This allows for greater proximity between the conductive strip and the C-shaped magnetic core. Finally, the current measurement generated by the sensor is reproducible and stable.

[0027] The centering element may include two intermediate walls inside the accommodating portion, the two intermediate walls forming the groove, and the C-shaped magnetic core includes two air gap surfaces that are parallel to each other, each air gap surface contacting one of the intermediate walls.

[0028] The device may further include a Hall effect sensor positioned in a groove in the receiving portion, the groove being formed between the intermediate walls.

[0029] The groove may have an flared inlet, and the inlet wall in the groove is formed at an angle between 30° and 90°, for example, 60°.

[0030] The centering element may include a protrusion that extends perpendicularly to the bottom into the receiving volume of the receiving portion, the protrusion contacting the inner surface of the C-core.

[0031] The number of pillars can advantageously be three.

[0032] The parts forming the accommodating portion may be made of plastic material, preferably polyphenylene sulfide.

[0033] The part forming the receiving portion may be an overmolded part on the conductive strip.

[0034] The C-shaped magnetic core can be a wound type core.

[0035] The device may include three conductive strips, three receiving portions, and three C-shaped magnetic cores.

[0036] The present invention also relates to a component comprising an inverter, a motor, and means as described above, wherein each conductive strip connects a power module of the inverter to a phase of the motor.

[0037] The present invention relates to a motor vehicle comprising components as described above, wherein the electric motor is configured to ensure all or part of the vehicle traction. Attached Figure Description

[0038] Other advantages, objects, and special features of the invention will become clearer from the following non-limiting description of at least one particular embodiment of the apparatus and method that are the subject of the invention, and with reference to the accompanying drawings, in which... - Figure 1 This is a schematic perspective view of a device according to an embodiment of the present invention; - Figure 2 This is a schematic front view of a housing portion for a C-shaped magnetic core, which can be used in a device according to the invention; - Figure 3 yes Figure 2 A schematic diagram of the cross-section of the receiving part; - Figure 4 yes Figure 2 and Figure 3 A schematic diagram of the receiving part, in which a C-shaped magnetic core is installed; - Figure 5 yes Figure 1 A schematic diagram of the cross-section of the device. Detailed Implementation

[0039] This specification is given as a non-limiting example.

[0040] Figure 1 An apparatus according to an embodiment of the invention is shown within a frame of a conductive bar assembly for connecting an inverter to a motor. In this case, the assembly includes three conductive bars 1. Each conductive bar 1 includes a first end 2 for connecting (e.g., welding to) an output conductive bar of an inverter power module. Each conductive bar 1 also includes a second end 3 for connecting (e.g., by screws) to a phase of the motor.

[0041] In the example shown here, the overmolded part 4 is formed around the conductive strip 1 to hold the conductive strip in place, protect the conductive strip, and insulate the conductive strip. The overmolded part 4 can be made of various plastic materials. For example, the overmolded part can be made of polyphenylene sulfide (PPS).

[0042] This material can be used to form complex shapes with very thin thicknesses.

[0043] Importantly, it is possible to determine the current flowing in each phase of the motor and therefore in each conductive bar 1. The current measurement is performed as follows. A C-shaped magnetic core (referenced as 5 in the figures, also referred to as C-core 5) is positioned around the conductive bar 1. According to various embodiments, the C-shape can be perfectly circular, or it can include straight branches configured as a “C”. C-core 5 is capable of concentrating the magnetic field created by the current flowing through the conductive bar. A sensor (typically a Hall effect sensor) is used to measure the current. C-core 5 has a general C-shape, as its name suggests. The two ends of the “C” are separated by an air gap 6. The Hall effect sensor is placed in the air gap of C-core 5, thereby allowing accurate and reliable measurement of the current in the conductive bar.

[0044] The C-core and sensor are advantageously positioned at the output of the inverter, i.e., close to the first end 2 of the conductive strip.

[0045] According to the present invention, each C-core is mounted in the receiving portion 7. In the example shown, the receiving portion 7 is integrally formed with the overmolded part 4.

[0046] Reference for 7-section housing Figure 2 , Figure 3 and Figure 4 To describe in more detail.

[0047] The receiving portion 7 includes a bottom 8 and a sidewall 9. The sidewall 9 is substantially perpendicular to the bottom 8. A receiving volume 10 is thus formed for receiving a C-core 5, which is surrounded by the sidewall 9. The receiving portion is advantageously configured such that the C-core 5 is received within the receiving portion, with a substantially constant gap J between the outer surface 11 of the C-core 5 and the sidewall 9 of the receiving portion 7. In the example shown here, however, as Figure 4 As shown, the sidewall 9 forms at least one (two in this case) concavité 12 to facilitate the introduction of liquid resin into the receiving portion 7.

[0048] In a variation, C-core 5 may be at least partially embedded in the adhesive (e.g., silicone or acrylic adhesive). For the remainder of this specification, it is assumed that C-core 5 is wholly or partially embedded in the resin, but this description applies to the adhesive with appropriate modifications.

[0049] The bottom 8 of the receiving portion 7 includes a support column 13. The support column 13 corresponds to a partial protrusion protruding into the receiving volume 10. The support column can have various shapes. The support column can be conical, truncated conical, prismatic, cylindrical, hemispherical, etc.

[0050] In this way, each pillar forms a small point-support surface for the C-core 5. The number of pillars is preferably at least three. The three pillars form balanced supports for the C-core within the receiving portion 7. This has several advantages. First, compared to the case where the support of the C-core in the receiving portion is plane-to-plane, the precise orientation of the C-core is better controlled and reproducible by using this support on point pillars (especially three pillars). Moreover, when manufacturing the receiving portion by molding or overmolding, using pillars as a reference is simpler and more reproducible than using a large reference surface (which must be perfectly flat and perfectly oriented). Finally, the pillars 13 create a space E between the bottom 8 and the C-shaped core 5 (in... Figure 5 (See in the middle).

[0051] The space E allows liquid resin to flow between the bottom 8 and the C-core 5. Therefore, due to the gap J and the space E, the C-core 5 can be completely immersed in the resin to fix and protect the C-core, thereby limiting the risk of trapped air bubbles in the resin.

[0052] Although pillar 13 guarantees the position of core 5, Figure 3 The example shown illustrates how to suggest a position for C-core 5 in a transverse plane parallel to the bottom 8 of the accommodating portion 7.

[0053] A centering element is disposed in the receiving portion 7 as a reference and mechanically engages with the C-core 5 to ensure the positioning of the C-core in the transverse plane (referred to as centering). In the preferred example shown, the centering component includes two intermediate walls 14. The C-core 5 includes two air gap surfaces 15 parallel to each other on both sides of its air gap 6. When the C-core is placed in the receiving portion 7, each air gap surface 15 contacts one of the intermediate walls 14. This ensures the position of the C-core in the receiving portion in a direction perpendicular to the air gap surfaces 15 and the intermediate walls 14.

[0054] Furthermore, the protrusion 16 is formed protruding from the bottom 8 and is configured to contact the inner surface 17 of the C-core 5 when the C-core 5 is positioned in the receiving portion 7, such as... Figure 4 As shown. In particular, the protrusion 16 is configured to ensure the centering of the C-core 5 in the receiving portion in a direction parallel to the air gap surface 15 and the intermediate wall 14.

[0055] Furthermore, a recess 18 suitable for receiving a Hall effect sensor is formed between the intermediate walls 14. The Hall effect sensor can be, for example, glued into the recess. Because the intermediate walls 14 can be very thin, especially when the receiving portion is made of PPS or other plastic materials with similar properties, the Hall effect sensor is positioned very close to the C-shaped magnetic core.

[0056] To facilitate the introduction of the sensor into the recess 18, the recess 18 may include a flared (e.g., chamfered) inlet. For example, the inlet wall in the recess may be formed at an angle β between 30° and 90°, such as 60° or approximately 60°. The term "approximately" is interpreted as indicating the corresponding value plus or minus 10%. Current sensors (typically Hall effect sensors) are often soldered to a PCB and are relatively long, which causes some positioning dispersion at the end of the current sensor to be introduced into the recess, and this angle allows for a certain degree of recentering of the sensor. This facilitates the automation of the placement of the sensor into the recess 18.

[0057] According to another aspect of the invention, contrary to what is typically observed in known systems, the receiving portion 7 does not have a wall that contacts or surrounds the conductive strip 1, i.e., it does not have a wall formed around the conductive strip 1 between the conductive strip 1 and the C-shaped magnetic core. This is made possible, on the one hand, by the very precise centering of the C-core 5, which is achieved as described above. Furthermore, the flow of liquid resin around the C-core is ensured by the support 13 and the gap J, ensuring the presence of resin between the conductive strip 1 and the inner surface 17 of the C-core, thereby guaranteeing good insulation between the C-core 5 and the conductive strip 1. In other words, except for the area of ​​the groove 18 (between the intermediate walls 14) and the area including the protrusion 16, the conductive strip is in direct contact with the resin filling the receiving portion 7, and the C-shaped magnetic core is wholly or partially embedded in the resin.

[0058] The absence of a wall also allows the conductive strip 1 to be very close to the C-shaped magnetic core 5, which improves the concentration of the magnetic field formed by the current flowing in the conductive strip. Due to this close proximity, current measurements performed by the Hall effect sensor mounted in the recess 18 are accurate and reliable.

[0059] This is also Figure 5 As can be seen, Figure 5 yes Figure 1 A cross-sectional view of the device in the plane of the conductive strip 1 at the location of the receiving part. Figure 5 The cross section AA is also Figure 1 As shown in the image. From Figure 5 The space E formed between the bottom 8 and the gap J is particularly visible above, allowing the core 5 C to be immersed in the resin R that completely fills the receiving portion 7. A cap 19 can be added at the opening of the receiving portion 7, especially before the resin hardens, to seal the receiving portion 7. This cap can be attached, particularly by means of the resin R.

[0060] Therefore, the device according to the invention can be obtained as follows. First, a receiving portion 7 is formed. Advantageously, the receiving portion can be formed by an overmolded part 4 of a conductive strip 1. The conductive strip 1 passes through the bottom 8 of the receiving portion 7. A C-shaped magnetic core 5 is disposed in the receiving portion. The position of the C-shaped magnetic core in depth and its orientation in a plane parallel to the bottom 8 are ensured by support on a support column 13. The centering of the C-shaped magnetic core is ensured by contact of the air gap surface 15 on the intermediate wall 14 and by the fit between the inner surface 17 of the C-core and the protrusion 16.

[0061] Once the C-core is in place, liquid resin is introduced into the receiving portion 7 via the recess 12. Specifically, one or more delivery nozzles are introduced into one or more recesses 12, and the receiving portion 7 is filled with liquid resin. In the example shown, the C-core 5 is completely embedded in the resin without any trapped air bubbles. The cover 19 is then placed in place. The resin hardens, thereby permanently holding and protecting the C-core and insulating it from the conductive strip. This also secures the cover 19. Finally, a Hall effect sensor is introduced into the recess 18, where it is secured. For example, the Hall effect sensor can be glued on.

[0062] Finally, the housing structure proposed in this invention can be easily used in a variety of applications (e.g., a series of electric motors) by simply changing the thickness of the C-shaped magnetic core.

[0063] This invention therefore proposes a device that allows for the precise and automatic placement of a C-shaped magnetic core around a conductive strip, enabling accurate and reliable current measurement using suitable sensors, particularly Hall effect sensors. The component configuration developed in this invention, which allows for the positioning and centering of the C-shaped magnetic core, also allows for easy flow of liquid resin within the receiving portion completely around the C-shaped core, enabling the C-shaped core to be embedded in the resin quickly and without air bubbles, which is of industrial interest. This invention also allows for the elimination of the need for a wall around the conductive strip between the conductive strip and the C-shaped magnetic core. This reduces the distance between the conductive strip and the C-shaped magnetic core, improving the concentration of the magnetic field by the C-shaped core.

[0064] In a device comprising multiple receiving portions and multiple C-cores, the dispersion of the positions and orientations of the C-cores is limited.

[0065] Glossary: ● 1: Conductive strip ● 2: The first end of each conductive strip ● 3: The second end of each conductive strip ● 4: Overmolded parts ● 5: C-shaped magnetic core, also known as C core ● 6: Air gap ● 7: Reception Section ● 8: Bottom ● 9: Sidewall ● 10: Receiving volume ● 11: Outer surface of C-core ● 12: Concave ● 13: Pillar ● 14: Intermediate wall ● 15: Air gap surface ● 16: Protrusion ● 17: Inner surface of C-core ● 18: Groove ● 19: Cover

Claims

1. An apparatus, the apparatus comprising: C-shaped magnetic core (5). A conductive strip (1) is provided, and the C-shaped magnetic core (5) is mounted around the conductive strip. The component forming the receiving portion (7) includes a bottom (8) and a sidewall (9), the bottom and the sidewall defining a receiving volume (10) of the receiving portion, the C-shaped magnetic core (5) being received in the receiving volume, the component forming a groove (18) in the air gap (6) of the C-shaped magnetic core (5), the groove being adapted to receive a current sensor, the receiving portion (7) including a centering element for centering the C-shaped magnetic core (5) in a transverse plane parallel to the bottom (8) of the receiving portion; The device further includes resin or adhesive in the receiving portion (7), and the C-shaped magnetic core (5) is at least partially embedded in the resin or adhesive. The characteristic feature is that the bottom (8) of the accommodating portion (7) includes a support column (13), and the C-shaped magnetic core (5) is supported on the support column. Furthermore, the conductive strip (1) passing through the bottom (8) is in direct contact with the resin or the adhesive.

2. The apparatus according to claim 1, wherein, The centering element includes two intermediate walls (14) inside the receiving portion (7), the two intermediate walls forming the groove (18), and the C-shaped magnetic core (5) includes two air gap surfaces (15) parallel to each other, each air gap surface (15) contacting one of the intermediate walls (14).

3. The apparatus according to claim 2, further comprising a Hall effect sensor positioned in a groove (18) of the receiving portion (7), the groove (18) being formed between the intermediate walls (14).

4. The apparatus according to claim 3, wherein, The groove (18) has a flared inlet, and the inlet wall in the groove is formed at an angle (β) between 30° and 90°, for example, 60°.

5. The apparatus according to any one of the preceding claims, wherein, The centering element includes a protrusion (16) that protrudes perpendicularly from the bottom (8) into the receiving volume (10) of the accommodating portion, the protrusion contacting the inner surface (17) of the C-core.

6. The apparatus according to any one of the preceding claims, wherein, The number of the pillars (13) is three.

7. The apparatus according to any one of the preceding claims, wherein, The parts forming the accommodating portion (7) are made of plastic material, preferably polyphenylene sulfide.

8. The apparatus according to any one of the preceding claims, wherein, The part forming the receiving portion (7) is an overmolded part (4) on the conductive strip (1).

9. The apparatus according to any one of the preceding claims, wherein, The C-shaped magnetic core (5) is a wound core.

10. The device according to any one of the preceding claims, the device comprising three conductive strips (1), three receiving portions (7) and three C-shaped magnetic cores (5).

11. A component comprising an inverter, a motor, and the apparatus of claim 10, wherein, Each conductive strip (1) connects the power module of the inverter to one phase of the motor.

12. A motor vehicle comprising the components according to claim 11, wherein, The electric motor is configured to ensure full or partial vehicle traction.

Images