Power electronics device with an integrated current sensor in a busbar unit; and electric machine

Abstract

The invention relates to a power electronics device (1) for an electric machine (2), having a DC-side busbar unit (3), an AC-side busbar unit (4) and at least one current sensor (5) that ascertains an electrical current value, wherein the at least one current sensor (5) is directly integrated into a conductor (6a, 6b, 7a, 7b, 7c) of the DC-side busbar unit (3) or the AC-side busbar unit (4). The invention also relates to an electric machine (2) having this power electronics device (1).

Description

[0001] Power electronic device with integrated current sensor in a busbar unit; and electrical machine

[0002] The invention relates to a power electronics device for an electrical machine, comprising a DC-side busbar unit, an AC-side busbar unit and at least one current sensor determining an electrical current value.

[0003] Furthermore, the invention relates to an electrical machine with this power electronics device.

[0004] Generic power electronic devices and electrical machines are already well known in the art. A generic design is disclosed, for example, in US 2022 / 0214382 A1.

[0005] However, it has generally been found that the current sensors used in the state of the art are designed and used in a relatively space-intensive manner.

[0006] It is therefore an object of the present invention to provide a power electronics device that, including the sensors it contains, is as compact and space-saving as possible. A further object is to reduce the number of connections. Fewer connections also means greater reliability and lower contact resistance.

[0007] This is achieved according to the invention in that the at least one current sensor is integrated or directly mounted on / in a conductor of the DC-side busbar unit or the AC-side busbar unit. Thus, the current sensor is directly attached to a conductor, which is preferably made of a sheet metal material. This results in a particularly flat design of the busbar unit with the current sensor.

[0008] Further advantageous embodiments are claimed in the dependent claims and explained in more detail below. Accordingly, it is also advantageous if the DC-side busbar unit and / or the AC-side busbar unit (each) are designed as a laminated structure and the at least one current sensor is integrated directly into the laminated structure. Preferably, conductors and insulation layers are arranged alternately one above the other, with the at least one current sensor also being placed at a point on the conductor and finally pressed together (under the influence of heat). The result is a structure with the smallest possible overall height.

[0009] For easy attachment of the current sensor, it is also advantageous if at least one current sensor is glued to the conductor.

[0010] Alternatively or in addition to this adhesive bond, it is further advantageous if the at least one current sensor is fastened to the conductor in a form-fitting manner, for example by clipping / snapping it on, or is fastened to the conductor in a force-fitting manner, for example by means of an additional screw (preferably made of plastic).

[0011] This allows the connection between the current sensor and the conductor to be further strengthened.

[0012] Furthermore, it is advantageous if both the DC-side busbar unit and the AC-side busbar unit are each equipped with at least one current sensor. This further reduces the required installation space.

[0013] It is also advantageous if the DC-side busbar unit has two current sensors, each integrated into a (different) of two mutually insulated (preferably parallel) conductors. This further optimizes current detection.

[0014] For the most precise current measurement, it is also advantageous to install a metallic shielding layer between the conductors of the DC-side busbar unit. Regarding the AC-side busbar unit, it is also advantageous to have two current sensors, more preferably even three current sensors, each integrated into one of two or three mutually insulated conductors. This also further optimizes current detection.

[0015] Current flow is further optimized when all (two or three) current sensors of the AC-side busbar unit are located in a common plane, i.e., are arranged coplanar to each other. Here, too, it is advantageous to install a metallic shielding layer between the respective current sensors of the AC-side busbar unit.

[0016] Furthermore, it is advantageous if the AC-side busbar unit is designed with multiple conductor layers in the direction of a motor-side phase connection. This counteracts the current displacement effect.

[0017] Furthermore, the invention relates to an electrical machine having a stator, a rotor and a power electronics device according to the invention connected to a coil arrangement of the stator or the rotor according to at least one of the previously described embodiments, wherein the conductors of the AC-side busbar unit of the power electronics device are each connected to a phase connection of the coil arrangement.

[0018] The invention will now be explained in more detail below with reference to figures, in which context various embodiments are also shown.

[0019] They show:

[0020] Fig. 1 is a plan view of a DC-side busbar unit of a power electronics device according to the invention according to a first embodiment, wherein two mutually insulated conductors are included, each of which is equipped with a current sensor, Fig. 2 is a sectional view of the DC-side busbar unit according to Fig. 1 in the region of a first conductor having a current sensor,

[0021] Fig. 3 is a perspective view of the power electronics device according to the invention with the housing partially hidden, wherein an internal structure of the power electronics device is clearly shown,

[0022] Fig. 4 is a plan view of a DC-side busbar unit according to a second embodiment, wherein the conductors accommodating the current sensors are now provided with a special structure / recess,

[0023] Fig. 5 is a plan view of an AC-side busbar unit of the power electronics device according to the invention, wherein a total of three current sensors are attached to three different conductors each,

[0024] Fig. 6 is a sectional view of the AC-side busbar unit according to Fig. 5 along one of the conductors, illustrating the current sensor mounted thereon, and

[0025] Fig. 7 is a schematic longitudinal sectional view of an electrical machine comprising a power electronics device according to one of the previously described embodiments.

[0026] The figures are merely schematic in nature and therefore serve exclusively to understand the invention. The same elements are provided with the same reference numerals. Furthermore, the various features of the different embodiments can, in principle, be freely combined with one another.

[0027] In conjunction with Figs. 3 and 7, the preferred area of ​​application of the power electronics device 1 according to the invention should first be noted. The power electronics device 1 is preferably part of an electric machine 2. The power electronics device 1 thus preferably serves to control the electric machine 2 in its operating state. The electric machine 2 is preferably used as the drive motor of a (more preferably purely battery-electrically powered) motor vehicle.

[0028] Fig. 7 also shows that the power electronics device 1, with its output-side connections / outputs (here three), is electrically connected to phase connections 16a, 16b, 16c of the electric machine 2, namely a coil arrangement 15 of the electric machine 2. In this embodiment, the coil arrangement 15 is formed as part of a stator 14, but can alternatively also be part of a rotor 19 of the electric machine 2. It should also be noted that, although three phases / phase connections 16a, 16b, 16c are present in this embodiment, this number of phases can, in principle, also vary.

[0029] A basic structure of the power electronics device 1 according to the invention can be seen in Fig. 3. A housing 12 of the power electronics device 1 is illustrated only halfway (namely, its lower half as viewed in the installed position), so that in particular the structure inside the housing 12 can be seen.

[0030] Fig. 4 shows power modules 18 connected to outputs of the power electronics device 1 in the power electronics device 1. A capacitor arrangement 13 (configured as a capacitor module, preferably a DC link capacitor module) is connected upstream of the three power modules 3.

[0031] The power modules 18 are connected to an AC side / to (AC) outputs of the capacitor arrangement 13. The power modules 18 are further connected to the outputs of the power electronics device 1 by means of an AC-side busbar unit 4, described in more detail below.

[0032] A DC side / a (DC) input of the capacitor arrangement 13 is connected to a current coupling 21. The current coupling 21 preferably has a DC-side busbar unit 3, described in more detail below. A current sensor 5 of the DC-side busbar unit 3 is also indicated in Fig. 4. Furthermore, an EMC filter 22 is connected upstream of the capacitor arrangement 13 and is directly connected to input-side terminals of the power electronics device 1 (not shown in detail here).

[0033] A preferred first embodiment of a power electronics device 1 according to the invention can be seen in conjunction with Figs. 1 to 4, 5, and 6. The power electronics device 1 is illustrated in Figs. 1, 2, and 5, 6, particularly with respect to its busbar units 3, 4. Fig. 4 is similar in design to Fig. 1, with the difference that the parallel busbars / conductors have a constriction at the point where the sensor is attached. This constriction amplifies the current density and thus also the measurement signal for the current sensor 5.

[0034] The power electronics device 1 accordingly has the DC-side and AC-side busbar units 3, 4, which are explained in more detail below. The DC side is understood to be the side of the capacitor arrangement 13 that is connected to an energy source / battery during operation, i.e., the area positioned between an input-side / battery-side connection and the capacitor module 13. The AC side is understood to be the side of the capacitor arrangement 13 that is further connected (via the power modules 18) to the electric machine 2 during operation, i.e., the area arranged between the capacitor arrangement 13 and an output-side / electric motor-side connection of the power electronics device 1.

[0035] The DC-side busbar unit 3 can be seen in more detail in a preferred embodiment in Figs. 1 and 2. Looking at these two figures together, it can be seen that this DC-side busbar unit 3 contains two conductors 6a, 6b (made of sheet metal) that run parallel to one another at least in some sections. The conductors 6a, 6b overlap towards their end sections 23a, 23b and are electrically decoupled from one another in these sections 23a, 23b by means of several insulation layers 9. A sandwich-like structure of the DC-side busbar unit 3 created in this way can be seen particularly well in Fig. 2. Accordingly, the conductors 6a, 6b are arranged at least in sections alternately with the insulation layers 9 on their sections 23a, 23b, forming a laminated structure.In a central section 24, which extends between sections 23a, 23b, the insulation layers 9 are recessed, and the conductors 6a, 6b run parallel to each other. However, a recess in the insulation film / insulation layer 9 is not absolutely necessary. Furthermore, the two conductors 6a, 6b are preferably arranged in one plane / coplanarly in this central section 24.

[0036] Furthermore, a metallic shielding layer 8 is provided, which, viewed in the intended installation position in the gravitational field, is arranged above the conductors 6a, 6b as shown in Fig. 2. A current sensor 5, which is mounted on a first conductor 6a shown in Fig. 2, protrudes through a recess / passage / window in this shielding layer 8.

[0037] The current sensor 5 is integrated into the first conductor 6a, i.e., glued directly thereto. The current sensor 5 preferably includes a printed circuit board 10. The printed circuit board 10 can, in principle, have different shapes and strengths and can be designed, for example, as a rigid or flexible plate or a layered structure. The printed circuit board 10 is preferably glued directly to a surface / top side of the first conductor 6a. However, the printed circuit board 10 can also be applied to the back of the first conductor 6a.

[0038] The attachment of a further current sensor 5 to the second conductor 6b, as can be seen in Fig. 1, is carried out in the same way as for the current sensor 5 to the first conductor 6a. Thus, the DC-side busbar unit 3 in this embodiment has two current sensors 5. Fig. 1 also shows that a further metallic shielding layer 8 is arranged to form a shielding wall between the parallel regions of the first conductor 6a and the second conductor 6b that accommodate the current sensors 5, such that it shields against magnetic interference signals between the current sensors 5.

[0039] In this context, it should be noted again that the DC-side busbar unit 3 is preferably constructed as a laminated structure. Thus, the current sensors 5 are also connected to the conductors 6a, 6b in a lamination process and integrated into the laminated structure.

[0040] It is also advantageous if the current sensors 5 are alternatively or additionally attached to the conductors 6a, 6b by means of an additional adhesive, or another force-fitting fastening method, such as by means of screws, or a form-fitting fastening method, such as by means of a locking geometry.

[0041] In conjunction with Fig. 4, an alternative design for the DC-side busbar unit 3 according to a further, second exemplary embodiment of the power electronics device 1 according to the invention is apparent. According to this design, the conductors 6a, 6b are each specially structured. Each conductor 6a, 6b has a recess in the central section 24, which forms a laterally open window 11. The goal is to reduce the conductor cross-section for a short section in order to increase the current density. Furthermore, it would also be possible to have the window 11 / the "window cutout" facing inwards or to attach it to both sides.

[0042] The recesses / windows 11 of the conductors 6a, 6b face away from each other. It can also be seen in Fig. 4 that each current sensor 5 is arranged at least partially above the cavity formed by the window 11 / projects into it. Figs. 5 and 6 further illustrate a preferred embodiment of an AC-side busbar unit 4, which is also used in the first embodiment of the power electronics device 1 according to the invention.

[0043] In this embodiment, the AC-side busbar unit 4 has three conductors 7a, 7b, 7c, which run at least in sections in a common extension plane and are thus arranged coplanar.

[0044] Here, too, each conductor 7a, 7b, 7c has a current sensor 5. The current sensors 5 are positioned on parallel sections of the three conductors 7a, 7b, 7c, as can be seen in Fig. 5.

[0045] With regard to the attachment of the respective current sensor 5 to the respective conductor 7a, 7b, 7c, reference is made to the previously described attachment of the current sensors 5 to the conductors 6a, 6b, which is carried out in a similar manner. Thus, the AC-side busbar unit 4 is also preferably designed as a laminated structure. The insulation layers 9 and shielding layers 8 running between the individual conductors 7a, 7b, 7c are particularly clearly visible in Fig. 6.

[0046] In the transverse direction to the conductors 7a, 7b, 7c, shielding layers 8 in the form of shielding walls are again introduced between each two adjacent current sensors 5.

[0047] Fig. 6 again shows that a thermally conductive layer 17, such as a TIM layer, for example a gap pad, is preferably inserted between an underside of the AC-side busbar unit 4 and a housing 12 of the power electronics device 1.

[0048] In this regard, it should also be noted that the current sensors 5, viewed along the extension of the conductors 7a, 7b, 7c, are arranged closer to a terminal of the power modules 18 than to an end region of the conductors 7a, 7b, 7c forming an electric motor-side terminal 20. It can also be seen here that the AC-side busbar unit 4 is designed in multiple layers on a side facing the three phases / phase terminals 16a, 16b, 16c of the electric machine.

[0049] In other words, with respect to the DC-side busbar unit 3, the two busbars (conductors 6a, 6b) of the laminated busbar (busbar unit 3) are guided in parallel in the current measurement area.

[0050] A current sensor 5 can be placed on both the DC+ busbar (second conductor 6b) and the DC- busbar (first conductor 6a). Optionally, the sensor electronics can be positioned on both busbars. Measuring on both the DC+ and DC- sides can increase measurement accuracy and enhance functional safety.

[0051] The current sensor electronics / current sensors 5 is / are mounted (e.g. by soldering) on ​​a (rigid) printed circuit board (PCB) or flexible printed circuit board (FPC) or on another structured substrate (IMS - Insulated Metal Substrate or DCB - Direct Copper Bonding).

[0052] This substrate / circuit board 10 is in turn attached to the busbar (possible connection technology: gluing, screwing with plastic screw, clipping).

[0053] The sensor PCB (circuit board 10) can be mounted directly on the busbar if the PCB can provide the required electrical insulation from below.

[0054] If the PCB is not electrically insulated on the underside, then the insulation layer 9 can be extended or extended over both busbars and the PCB is attached to the insulation layer 9.

[0055] The laminated busbar can be optionally structured to increase the current density at desired locations. A conductor layer / shielding layer is integrated into the laminated busbar as a shield. This shielding prevents the magnetic fields around the DC+ and DC- conductors from influencing each other. The goal is to increase the measurement accuracy of current sensor 5(s).

[0056] With respect to the AC-side busbar unit 4, the three conductor layers (conductors 7a, 7b, 7c) connected to the various phases on the power module 18 or the electric machine 2 are arranged side by side. As with a molded busbar, the phase conductors can be placed relatively close to one another.

[0057] Insulation layers 9 are applied above and below the conductor layers.

[0058] One possible implementation could be that the conductor layers and insulation layers are designed in the form of a laminated busbar.

[0059] A conductor layer (shielding layer 8) is integrated into the laminated busbar as a shield. This shielding prevents the magnetic fields around the conductors 7a, 7b, 7c of the individual phase from influencing each other. The goal is to increase the measurement accuracy of the current sensors 5.

[0060] In a further design variant, each of the phases can be constructed as a multilayer conductor (e.g., instead of a 3 mm thick conductor, a conductor with three layers of 1 mm thickness). The multilayer structure can reduce the effect of current displacement to a certain extent.

[0061] Additional conductor layers / shielding layers 8 can be integrated above and below the current-carrying conductor layers for shielding. The goal is to reduce EMC interference – similar to a shielded cable. It also ensures optimal thermal connection between the busbar and the inverter housing (housing 12).

[0062] Thus, according to the invention, one or more current sensors 5 are integrated on the DC busbar (DC-side busbar unit 3) and the AC busbar (AC-side busbar unit 4) as an inverter application. This means that the current sensor 5 is not a separate component that must be connected to the busbar in an additional process step. Shielding elements (shielding layers 8) are integrated into the busbar in the area of ​​the current sensors to limit the influence of magnetic fields in the conductor.

[0063] Shielding layers (shielding layers 8) can be integrated on the AC busbar at the phase outputs to reduce EMC interference.

[0064] List of reference symbols

[0065] power electronics device electrical machine

[0066] DC-side busbar unit AC-side busbar unit Current sensor a First conductor of the DC-side busbar unitb Second conductor of the DC-side busbar unita First conductor of the AC-side busbar unitb Second conductor of the AC-side busbar unitc Third conductor of the AC-side busbar unit Shielding layer Insulation layer 0 Printed circuit board 1 Window 2 Housing 3 Capacitor module 4 Stator 5 Coil assembly 6a First phase connection 6b Second phase connection 6c Third phase connection 7 Thermally conductive layer 8 Power module 9 Rotor 0 Connection 1 Current coupling 2 EMC filter 3a First section 3b Second section 4 Middle section

Claims

Patent claims 1 . Power electronics device (1) for an electrical machine (2), comprising a DC-side busbar unit (3), an AC-side busbar unit (4) and at least one current sensor determining an electrical current value (5), characterized in that the at least one current sensor (5) is integrated directly on a conductor (6a, 6b, 7a, 7b, 7c) of the DC-side busbar unit (3) or the AC-side busbar unit (4).

2. Power electronics device (1) according to claim 1, characterized in that the DC-side busbar unit (3) and / or the AC-side busbar unit (4) are / are designed as a laminated structure and the at least one current sensor (5) is directly integrated into the laminated structure.

3. Power electronics device (1) according to claim 1 or 2, characterized in that the at least one current sensor (5) is glued onto the conductor (6a, 6b, 7a, 7b, 7c).

4. Power electronics device (1) according to one of claims 1 to 3, characterized in that the at least one current sensor (5) is fastened to the conductor (6a, 6b, 7a, 7b, 7c) in a form-fitting or force-fitting manner.

5. Power electronics device (1) according to one of claims 1 to 4, characterized in that both the DC-side busbar unit (3) and the AC-side busbar unit (4) are each equipped with at least one current sensor (5).

6. Power electronics device (1) according to one of claims 1 to 5, characterized in that the DC-side busbar unit (3) has two current sensors (5), each of which is integrated on one of two mutually insulated conductors (6a, 6b, 7a, 7b, 7c).

7. Power electronics device (1) according to claim 6, characterized in that a metallic shielding layer (8) is attached between the conductors (6a, 6b, 7a, 7b, 7c) of the DC-side busbar unit (3).

8. Power electronics device (1) according to one of claims 1 to 7, characterized in that the AC-side busbar unit (4) has two current sensors (5), each of which is integrated on one of two mutually insulated conductors (6a, 6b, 7a, 7b, 7c).

9. Power electronics device (1) according to claim 8, characterized in that the two current sensors (5) of the AC-side busbar unit (4) are arranged in a common plane.

10. Electrical machine (2) with a stator (14), a rotor (19) and a power electronics device (1) connected to a coil arrangement (15) of the stator (14) or the rotor (19) according to one of claims 1 to 9, wherein the conductors (6a, 6b, 7a, 7b, 7c) of the AC-side busbar unit (4) of the power electronics device (1) are each connected to a phase connection (16a, 16b, 16c) of the coil arrangement (15).

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