Power electronic circuit arrangement and power converter

Abstract

The invention relates to a power electronic circuit arrangement comprising a multilayer printed circuit board (10) with a conductor track arrangement formed in several layers, and comprising components arranged on the printed circuit board (10) and electrically contacted via the conductor track arrangement. In order to minimize heat loss in the case of intersecting conductor tracks with high currents, the circuit arrangement, according to the invention, includes a first busbar (20) and a second busbar (30) that crosses it in plan view and includes a current-sensing resistor (33), wherein in a crossing region of the two busbars (20, 30), the first busbar (20) is formed by conductor tracks formed in at least 80% of the layers, which are electrically connected to each other via vias (25).and the second busbar (30) is formed by a first busbar section (31) and a second busbar section (32), each formed by conductor tracks extending in at least 80% of the layers, including an uppermost of these layers, which are electrically connected to each other via vias (35), and by the current-sensing resistor (33), which is arranged on a top surface (12) of the circuit board (10) bridging the first busbar (20) and is electrically contacted on both sides of it by the conductor track formed in the uppermost layer of the respective first and second busbar sections (31, 32).

Description

[0001] The present invention relates to a power electronic circuit arrangement according to the preamble of claim 1, in particular for example for the implementation of a power converter (rectifier, DC-DC converter, inverter or converter) and in particular for example for use in vehicles.

[0002] Such a circuit arrangement is known in various embodiments from the prior art and comprises a multilayer printed circuit board, i.e., a printed circuit board with a conductor arrangement formed in several layers, wherein these layers comprise a first layer arranged on a top side of the printed circuit board and one or more further layers arranged below it. Furthermore, the circuit arrangement comprises components arranged on the printed circuit board and electrically contacted via the conductor arrangement.

[0003] Unless explicitly stated otherwise below, the terms "layer" and "layers" used here refer only to those layers of the printed circuit board (PCB) that contain electrically conductive material (e.g., copper) to form conductive traces. The entirety of the conductive traces formed on or within the PCB by the electrically conductive material, including the vias typically provided for electrical connections between traces of different layers, constitutes the aforementioned conductive trace arrangement of the PCB. It is understood that the PCB also contains electrically insulating material between adjacent layers (conductor layers). Commonly used materials for this purpose include, for example, epoxy resin systems such as FR-4 or polyimide. Particularly in PCBs for power electronic circuits, ceramic materials are also frequently used for this purpose.

[0004] The components electrically contacted via the conductor track arrangement can include, in particular, power semiconductor components such as diodes, transistors (e.g., MOSFETs), thyristors, etc. Furthermore, depending on the application, other components, and especially passive components such as resistors, inductors, capacitors, etc., can also be arranged on the circuit board.

[0005] DE 10 2020 214 311 A1 discloses a printed circuit board arrangement with a printed circuit board having at least two current-conducting layer layers, wherein the current-conducting layer layers extend in the axial direction of the printed circuit board and are arranged successively in the thickness direction of the printed circuit board, characterized in that the printed circuit board arrangement has a busbar which is arranged on one of the side surfaces of the printed circuit board and is contacted with at least a part of, in particular all, the current-conducting layer layers of the printed circuit board.

[0006] DE 10 2019 135 274 A1 relates to a power module with a printed circuit board on which at least one power component is arranged. Furthermore, the power module includes at least one busbar for connecting the power module to at least one potential. The printed circuit board has at least one through-hole through which the at least one busbar is thermally connected to the at least one power component. Also disclosed are a power converter and a motor vehicle component, each with such a power module.

[0007] DE 10 2009 022 110 A1 discloses a printed circuit board arrangement, in particular a multilayer printed circuit board arrangement, with at least one low-current conductor track, wherein the printed circuit board arrangement is suitable for mounting with at least one electronic power component to be cooled, wherein the printed circuit board consisting of a non-conductive material comprises at least one cooling inlay embedded in the printed circuit board for cooling the power component, wherein the cooling inlay at least partially forms a high-current conductor element for the at least one electronic power component, wherein the conductor cross-section or the current-carrying capacity of the high-current conductor element is significantly higher than the conductor cross-section or the current-carrying capacity of the low-current conductor track, and wherein the high-current conductor element is used and / or co-used for electrical contacting the power component.

[0008] DE 100 63 367 A1 relates to an electric motor vehicle lock module with a body made of injection-molded plastic, which serves to hold electrical components and is embedded in the conductor tracks which electrically connect the electrical components to each other according to a predetermined circuit, wherein the circuit comprises at least a first and a second conductor track which cross without touching each other, and wherein a serially arranged electrical component is located in the first conductor track.

[0009] DE 39 20 686 A1 discloses an electrical connection or distribution box for the electrical system of a motor vehicle, which includes flat parts for heat dissipation. These flat parts are formed on upright or raised sections of busbars and do not protrude higher than the busbars. They extend essentially parallel to an electrically insulating circuit board and do not require any increase in the dimensions of the connection or distribution box.

[0010] In power electronic circuit arrangements known from the prior art, printed circuit boards (PCBs) are often used to conduct both small signal currents and high operating currents. The components can be electrically interconnected by means of the multilayer conductor arrangement, e.g., copper traces distributed across several layers of the PCB, as well as vias to create electrical connections between traces of different layers. To measure the aforementioned operating currents, low-resistance resistors (so-called current-sensing resistors or shunts) are often used, which can be soldered, for example, onto a surface (top or bottom) of the PCB.

[0011] Due to specifications regarding the circuit design ("circuit diagram") including the components and their current flow to each other, regarding the positioning of inputs and outputs of the circuit arrangement, as well as regarding mechanical aspects (dimensioning etc.) and physical implementation (e.g. heat dissipation etc.), the optimal arrangement of the components and the conductor tracks, especially for example for carrying relatively high currents, in the available layers of the printed circuit board often presents a difficult challenge.

[0012] Optimal design takes into account factors such as the size of the printed circuit board, the power dissipation, and the temperature ranges in which the circuit arrangement is to be used. High currents, such as the aforementioned operating currents, necessitate large conductor cross-sections to keep electrical losses within acceptable limits.

[0013] A conductor for carrying a relatively high current is often also referred to as a "busbar" and, in known power electronic circuit arrangements of the type of interest here, is often realized from several conductor tracks running parallel to each other (in different positions of the printed circuit board) and electrically connected to each other via vias.

[0014] Problematic situations arise, for example, when two such busbars must cross according to a predefined circuit design. In the crossing area of ​​the busbars, this reduces the cross-section per busbar to 50% of the maximum cross-section available due to the layer structure of the printed circuit board, in known designs.

[0015] Furthermore, in known circuit arrangements, e.g., for current regulation and / or overcurrent protection, current-sensing resistors are often used, through which a high operating current to be measured is passed. Such current-sensing resistors develop a high current despite their low resistance value (e.g., less than 10 ohms) due to the higher currents. -1 Ω) generates significant heat that must be dissipated accordingly.

[0016] It is an object of the present invention to eliminate or at least mitigate the problems mentioned above in a power electronic circuit arrangement of the type mentioned at the outset, and thus in particular to provide a circuit arrangement which generates low heat loss even with crossing conductor tracks and high currents.

[0017] According to the present invention, this problem is solved by a circuit arrangement according to claim 1. The dependent claims relate to advantageous embodiments of the invention. The invention advantageously combines the possibility of measuring a high current with a current-sensing resistor in the circuit arrangement with a reduction or minimization of line losses in crossing lines for carrying high currents. These latter lines are hereinafter also referred to as "busbars".

[0018] The power electronic circuit arrangement according to the invention is characterized in that it comprises a first busbar and a second busbar which crosses the first busbar when viewed from above on the circuit board and includes a current-sensing resistor, and in a crossing area of ​​these two busbars - the first busbar is formed by conductor tracks formed in at least 80% of the layers, preferably all (i.e. 100%) of the layers, which are electrically connected to each other via vias, and - the second busbar is formed by a first busbar section and a second busbar section, each formed by conductor tracks in at least 80% of the layers, comprising the first layer, preferably all (i.e. 100%) of the layers, which are electrically connected to each other via vias, and by the current-sensing resistor, which is arranged on the top side of the printed circuit board bridging the first busbar and is electrically contacted on both sides of this bridging point on the conductor track formed in the first layer of the respective first and second busbar sections.

[0019] The term "power electronic" is to be interpreted broadly and, in the context of the invention, means that a comparatively high electrical power is involved for electronic devices, which is generated or controlled by the circuit arrangement during operation. This is generally the case, for example, when the circuit arrangement is intended for the generation and / or control of electrical energy not solely for data processing, but rather for supplying this energy to "electrical loads." This refers primarily to loads whose power requirements can reach values ​​of at least 100 W, and in particular at least 1 kW (up to a maximum of 50 kW in many applications).

[0020] In this context, the term "busbar" as used in the invention can also be understood to mean that a current flowing via the busbar during operation is intended for the purpose of transmitting electrical energy for purposes other than pure signal or data transmission. This can include, in particular, applications where, during operation of the circuit arrangement, electrical power values ​​exceeding 100 W, especially exceeding 1 kW (and, for example, a maximum of 40 kW), are reached and transmitted via the busbar.

[0021] The “crossing area” within the meaning of the invention comprises at least the area viewed in a top view of the circuit board in which the conductor tracks formed to create the two busbars overlap.

[0022] In the invention, the two intersecting busbars, i.e., the first busbar and the second busbar, are each advantageously formed using several, specifically at least 80% of the available layers. If the circuit board has only two or three layers in total, these are at least two layers. If the circuit board has four layers in total, these are at least three layers, and so on.

[0023] In one embodiment of the circuit arrangement, the printed circuit board has at least three layers, i.e., the first layer on the top side of the board and at least two further layers below it, i.e., inside the board and optionally on a bottom side of the board. Preferably, the printed circuit board has at least four and more preferably at least five layers.

[0024] The terms "top," "bottom," and similar terms such as "upper," "lower," "bottom," "underside," "below," etc., serve only to simplify the description of geometric directions or the relative positions of components within the circuit arrangement. Such terms therefore do not represent any restriction regarding the orientation of the circuit arrangement or its components in use (the circuit arrangement, or its printed circuit board, for example, can be used with its top side facing down or in any other direction).

[0025] Advantageously, the invention enables a significant reduction in the electrical resistance of the first and second busbars, resulting in less power loss during operation of the circuit arrangement and consequently a corresponding reduction in the overall power loss of the circuit arrangement. This allows, for example, higher currents to be carried with comparable printed circuit board dimensions when using the invention, and / or the dimensions of the printed circuit board and thus the circuit arrangement can be reduced.

[0026] In one embodiment of the circuit arrangement, the lowest layer of the further layers is provided inside the printed circuit board, in which case a heat-conducting layer (e.g. layer of printed circuit board substrate material such as FR-4 or ceramic material or metallization layer) and a heat sink thermally connected via this heat-conducting layer can be arranged underneath on the underside of the printed circuit board (e.g. soldered or glued, or connected via a sintered layer).

[0027] In another embodiment of the circuit arrangement, the lowest layer of the further layers is provided on the underside of the printed circuit board, in which case, for example, one or more of the components of the circuit arrangement can also be electrically contacted on the underside of the printed circuit board via conductor tracks formed there.

[0028] In one embodiment of the circuit arrangement, the conductor track arrangement of the circuit board is formed with conductor tracks made of a copper material.

[0029] The printed circuit board can have a layer of electrically non-conductive material between adjacent layers (with electrically conductive material) for electrical insulation between the respective conductor tracks. Such layers can be formed, for example, from an epoxy resin system such as FR-4 or from a ceramic material (e.g., based on aluminum nitride or the like).

[0030] In a preferred embodiment of the invention, all available layers, i.e., the first layer on the top side of the circuit board and all further layers arranged below it, are used to form the first busbar and / or second busbar.

[0031] In the first busbar, the advantage of low electrical resistance in the crossing area of ​​the busbars is consistently achieved through the utilization of at least 80% of the layers. In the second busbar, this advantage applies to the first busbar section and the second busbar section, which together with the current-sensing resistor form the second busbar. The connections (e.g., terminals) of the current-sensing resistor can be electrically connected to the conductor tracks formed in the first layer of the two busbar sections, for example, by soldering, welding (e.g., ultrasonic welding), or via a sintered layer.

[0032] In one embodiment of the invention, at least one of the first and second busbars of the circuit arrangement is provided to carry a current (either direct or alternating current) during operation of the circuit arrangement, the current strength of which can assume values ​​of at least 20 A, in particular at least 50 A (and, for example, a maximum of 1000 A). In one embodiment of such a use of a circuit arrangement according to the invention, this current strength is at least 500 A.

[0033] Within the scope of the invention, power electronic uses or configurations of the circuit arrangement, for example as an inverter, converter (AC / AC converter), rectifier (AC / DC converter) or DC / DC converter, or as a part of such a device (power converter), are particularly interesting, since in such devices the circuit boards in question are often used for conducting both small signal currents (e.g. control signals and / or sensor signals) and high operating currents (e.g. input current, output current).

[0034] In one embodiment of the invention, the circuit arrangement is used or configured as an inverter (or part of an inverter), for example, for the pulsed power supply of an electric machine, in particular, for example, an electric machine in a powertrain of an electric or hybrid vehicle (e.g., BEV, HEV, etc.). In this application, a relevant busbar of the circuit arrangement can, for example, represent an electrical conductor through which an input-side direct current or an output-side alternating current (e.g., phase current of a multi-phase electric machine) is supplied.

[0035] Furthermore, the circuit arrangement's use and configuration as a rectifier (or as part of a rectifier) ​​are also of interest, for example, in a vehicle charging device. This device connects an electrical charging infrastructure, such as an electrical supply network (with alternating current), to a vehicle's electrical energy storage system containing an electric battery, enabling the charging of the vehicle's battery (with direct current). In this application, the busbar in question can, for example, represent an electrical conductor through which an input alternating current (e.g., one of several phases) or an output direct current is carried.

[0036] Finally, the circuit arrangement's use and configuration as a DC-DC converter (or as part of such a converter) are also of interest, for example, in a vehicle to transfer electrical energy between different vehicle electrical systems. Furthermore, the DC-DC converter in a vehicle can also be a component of a vehicle charging system (e.g., an on-board battery charger), which, installed on board the vehicle, facilitates energy transfer between, on the one hand, an electrical charging infrastructure (e.g., the power grid) and, on the other hand, the vehicle's electrical energy storage system containing an electric battery. In these applications, the busbar in question can, for example, represent an electrical conductor through which an input or output DC current is carried.

[0037] It is generally preferred if the conductor tracks intended to form the two busbars have a uniform width, if possible, when viewed along their respective paths.

[0038] In one embodiment of the circuit arrangement, the conductor tracks forming the first busbar and / or the conductor tracks forming the two busbar sections of the second busbar, viewed from above on the circuit board, run at least approximately congruently to each other. This alignment can be straight, at least in the area where the two busbars cross.

[0039] In some designs, however, it can be advantageous to provide an at least approximately identical path (when viewed from above) only for the conductors in the subsequent layers forming the first and / or second busbars, and to provide a different shape for conductors in the first layer (on the top side of the circuit board). The conductors with an identical path can each have a uniform width when viewed along their respective paths.

[0040] In an embodiment advantageous for achieving a further reduction in the electrical resistance of the busbars, (at least) the conductor tracks provided for forming the first busbar and / or the second busbar (or all conductor tracks of the conductor track arrangement) can be made relatively thick. In one embodiment, the thickness of these conductor tracks (or all conductor tracks of the conductor track arrangement) is, for example, at least 70 µm, in particular at least 100 µm. On the other hand, this thickness can be, for example, a maximum of 300 µm, in particular a maximum of 200 µm.

[0041] Furthermore, it is advantageous to design the conductor tracks intended for forming the first busbar and / or the second busbar to be relatively wide. In one embodiment, the width of these conductor tracks is, for example, at least 25 times, and in particular at least 50 times, their thickness. On the other hand, this width can be, for example, a maximum of 400 times, and in particular a maximum of 200 times, this thickness.

[0042] In one embodiment of the circuit arrangement, the conductor tracks formed in the first layer, viewed from above on the circuit board, taper towards the center of the intersection area of ​​the two busbars. This embodiment is particularly advantageous when the longitudinal extent of the current-sensing resistor (or at least a body of the current-sensing resistor), viewed in the direction of the second busbar, is smaller than the width provided for conductor tracks forming the first busbar in the intersection area. In this case, the ability of the current-sensing resistor to bridge the conductor track of the first busbar in the first layer can be achieved by providing a corresponding "constriction" in the conductor track width in the first layer for the first busbar. Such a constriction can, for example, be...The conductor track must be symmetrical to a center line of the respective conductor path. In contrast, conductor tracks of the first busbar formed below, i.e., in the further layers of the printed circuit board, can run without such a constriction (and here, for example, be congruent with each other and / or have a uniform width in the direction of travel).

[0043] In one embodiment, the two busbars cross each other in the intersection area, viewed from above on the circuit board, at an angle of at least approximately 90°, e.g. deviating by a maximum of 10°.

[0044] In one embodiment, the current-sensing resistor has a rectangular contour when viewed from above on the circuit board.

[0045] In one embodiment, the current-sensing resistor has a plate-shaped body and connecting tabs projecting laterally from opposite end faces for electrical contact. These connecting tabs can, for example, be bent downwards to bridge a vertical gap between the resistor body and the surface of the first layer of the printed circuit board. The connecting tabs can, for example, have the same width as the body and be bonded flat to the upper surface of the respective conductor track on their undersides.

[0046] In one embodiment, the current measuring resistor (e.g. on connecting tabs of the type mentioned above) is electrically contacted by means of soldering or welding (e.g. ultrasonic welding) or via a sintered layer on the relevant conductor tracks in the first layer (of the two busbar sections of the second busbar).

[0047] In one embodiment of the circuit arrangement, a current-sensing signal conductor branches off from at least one of the two conductor tracks in the first layer, where the current-sensing resistor is electrically contacted, and leads away from the intersection area. In this case, each of the at least one current-sensing signal conductor can branch off, for example, at a point that, viewed from above on the circuit board, lies on a center line of the respective conductor track.

[0048] In a further development of this embodiment, it is provided that in the intersection area, a current-measuring signal conductor branches off from each of the conductor tracks formed in the first layer, where the current-sensing resistor is electrically contacted. One of the two current-measuring signal conductor tracks leads away from the intersection area, passing under the current-measuring resistor. Advantageously, both current-measuring signal conductor tracks can thus be led out of the intersection area "on the same side" with respect to both the first and second current rails.

[0049] For example, the two current measurement signal traces in the relevant area of ​​the circuit board can be routed, for example, in parallel and with a small separation, to a circuit component (e.g., comprising a measuring amplifier) ​​of the circuit arrangement intended for processing and / or evaluating the current measurement signals. Alternatively, this continuation could also be provided, for example, to a connection or interface device of the circuit arrangement, such as for processing and / or evaluating the current measurement signals by an external device.

[0050] Since each current-measuring signal conductor typically only needs to carry a very small current, the (at least one) current-measuring signal conductor can be designed with a very small width, e.g., a maximum of 2 mm or a maximum of 1 mm (on the other hand, e.g., at least 0.2 mm, in particular at least 0.5 mm). In one embodiment, the width of the (at least one) current-measuring signal conductor is, for example, a maximum of 0.05 times, in particular a maximum of 0.01 times, a maximum width of the two conductor rails, and / or at least 0.001 times the maximum width of the two conductor rails.

[0051] In one embodiment of the invention, a heat sink is attached to the underside of the printed circuit board. The heat sink can be attached to the underside of the printed circuit board, for example, via a thermal interface material (TIM), such as a heat-conducting layer (e.g., an electrically insulating one). The connection can be made, for example, to a layer of epoxy resin or ceramic material, or a layer of metal material (metallization layer) provided on the underside of the printed circuit board.

[0052] Alternatively or additionally, a heat sink can be attached to the top side of the printed circuit board (PCB), for example, via a thermally conductive material (such as TIM, which is electrically insulating). Such a heat sink on the top side can be positioned and shaped so that the heat generated by the current-sensing resistor is transferred via a surface of the resistor to the thermally conductive material and then directly to the heat sink (without having to pass through the PCB to a heat sink located on the underside). For example, the heat sink on the top side of the PCB can have a recess (cavity) on its underside to accommodate the current-sensing resistor.Direct cooling of the resistor by means of the heat sink located on the top of the circuit board, especially in combination with the use of at least 80% (in particular all) of the layers to form the first busbar, significantly reduces the thermal resistance between the measuring resistor and the environment. Heat generated by the current measuring resistor can be dissipated downwards to the first busbar via thermal conduction and / or thermal radiation and from there distributed laterally along the first busbar.

[0053] In a frequently advantageous embodiment, a heat sink is arranged on both the top and bottom surfaces of the printed circuit board. These two surfaces of the circuit board can be connected to the respective (upper or lower) heat sink, in particular via an electrically insulating thermal interface material.

[0054] In all the above-mentioned embodiments with (at least) one heat sink, it can be provided that such a heat sink has a cooling channel through which a cooling medium such as cooling water can flow during operation of the circuit arrangement.

[0055] The invention is further described below with reference to exemplary embodiments and the accompanying drawings. These schematically depict: Fig. 1 a perspective view of a circuit arrangement in the area of ​​a crossing of two busbars of the circuit arrangement according to an embodiment, Fig. 2. A top view of the upper side of a printed circuit board of the circuit arrangement of Fig. 1, Fig. 3. A top view of the underside of the circuit board of Fig. 2, Fig. 4 A perspective sectional view of a circuit arrangement similar to that of Fig. 1, however with a heat sink on the underside of the circuit board, Fig. 5 a perspective sectional view of a circuit arrangement similar to that of Fig. 1, however with a heat sink on the top of the circuit board, and Fig. 6. A perspective sectional view of a circuit arrangement similar to that of Fig. 1, however with heat sinks on the top and bottom of the circuit board.

[0056] Fig. Figure 1 illustrates an embodiment of a power electronic circuit arrangement and, for the sake of simplicity, shows only an area in which two busbars 20, 30 formed on a multilayer printed circuit board 10 of the circuit arrangement and running in a straight line intersect at an angle of 90° when viewed from above.

[0057] The circuit arrangement comprises the multilayer printed circuit board 10 with a conductor track arrangement formed in several layers (6 layers in the example), wherein these layers comprise a first layer arranged on a top surface 12 of the printed circuit board 10 and several further layers arranged below it (5 further layers in the example). The circuit arrangement further comprises components arranged on the printed circuit board 10 and electrically contacted via the conductor track arrangement, of which in Fig. Figure 1, however, shows only a current-measuring resistor 33. The resistor 33 serves to measure a current flowing through the second busbar 30 during operation of the circuit arrangement. The conductor arrangement consists of copper conductors (and vias described below) distributed across the layers of the printed circuit board.

[0058] Fig. Figure 1 shows only a detail of the circuit arrangement that is essential for understanding the invention in this example and omits the depiction of any further components and conductor tracks that may be present in this area for electrically contacting such further components. Such components may include, for example, power semiconductor components such as diodes and / or transistors, one or more additional resistors, coils, capacitors, etc. Furthermore, the circuit arrangement may also include, for example, one or more electrical connection devices such as connectors (sockets), etc., through which the circuit arrangement is integrated into a relevant electrical environment (e.g., in a vehicle). The connection device may have electrical contacts that are electrically connected to the busbars 20, 30 in order to supply a respective current to the respective busbar or...to route from this busbar out of the circuit arrangement. Depending on the design of the circuit arrangement, further such contacts may be provided, for example to transmit supply potentials (supply voltage, etc.) or electrical data signals (e.g., control signals and / or sensor signals).

[0059] The circuit arrangement can, for example, be used to implement a power converter (e.g., located in a vehicle), in which case the busbars 20, 30 shown in the figure, as well as any additional busbars (not shown in the figure), can each carry an input current or an output current of the power converter. Such a power converter can also be composed of several circuit arrangements of the type described here, or may have several such circuit arrangements, particularly, for example, in the case of a power converter with a multi-phase alternating current input or output (e.g., one circuit arrangement per phase).

[0060] A special feature of the circuit arrangement in the illustrated embodiment is that - that the first busbar 20 is formed by conductor tracks (here: copper conductor tracks) formed in all of the (in the example: 6) layers, which are electrically connected to each other via vias 25 (here: copper-plated holes), and - that the second busbar 30 is formed by a first busbar section 31 and a second busbar section 32, each formed by conductor tracks (here: copper conductor tracks) formed in all of the (in the example: 6) layers, which are electrically connected to each other via vias 35 (here: copper-plated holes), and by the current-sensing resistor 33, which is arranged on the top side 12 of the circuit board 10 bridging the first busbar 20 and is electrically contacted on both sides of this bridging point (on both sides of the first busbar 20) on the conductor track formed in the first layer of the respective first and second busbar sections 31, 32.

[0061] The current measuring resistor 33, via which the busbar sections 31, 32 of the second busbar 30 are electrically connected to each other, enables the measurement of a current flowing via the second busbar 30 during operation of the circuit arrangement (by tapping and evaluating a measuring voltage drop across the current measuring resistor 33).

[0062] In this example, the current-measuring resistor 33 has a plate-shaped body, meaning its transverse dimensions are significantly larger than its vertical dimensions (height, for example, approximately 1-2 mm). Viewed from above, the body appears roughly square, but it could also have a different shape, such as an elongated rectangle.

[0063] The body can be made, for example, of a metal alloy that has a low specific electrical resistance (e.g., on the order of about 10 to 10). -1 Ω mm 2 / m), which is only slightly temperature-dependent, such as a material offered under the trade name "Manganin", "Konstantan" or "Zeranin" or a material with similar properties. The advantage of this is that the voltage drop (measuring voltage) measured across the current-measuring resistor 33 for current measurement purposes is only minimally affected by any temperature fluctuations of the current-measuring resistor 33.

[0064] The body, or rather this material, forms the functional core of the current-sensing resistor 33. Laterally projecting and, in this example, downwardly bent connecting tabs are attached to opposite end faces of the body. These tabs, made of copper, are electrically contacted on both sides of the first busbar 20 by the conductor tracks of the second busbar 30 formed in the first layer. The connecting tabs of the current-sensing resistor 33 are soldered to the respective conductor tracks, thus ensuring a mechanical, electrical, and thermal connection of the current-sensing resistor 33 to the copper conductor tracks of the second busbar 30 formed in the first layer. In an advantageous embodiment, a thermally conductive material or layer can be provided between the underside of the current-sensing resistor and the top side of the circuit board.

[0065] Fig. Figure 2 shows a top view of the top of the circuit board 10 (without the current-sensing resistor 33) and Fig. 3 a top view of the underside of the circuit board 10.

[0066] The circuit arrangement shown is designed according to the Fig. 1, Fig. 2 to Fig. 3 advantageously combines the possibility of measuring a current flowing via the second busbar 30 (by means of the current measuring resistor 33) in the circuit arrangement with a maximization of a conductor cross-section (and consequently minimization of electrical conductor losses) at the intersecting busbars 20, 30.

[0067] The circuit arrangement comprises the first busbar 20, which extends in a first direction and is formed by conductor tracks that are present in all (here: 6) layers of the printed circuit board (circuit carrier) 10 in order to minimize line losses. Furthermore, the circuit arrangement comprises the second busbar 30, which extends transversely to the first direction in a second direction (here: at a 90° angle) and, apart from the section formed by the current-sensing resistor 33, i.e., in the first and second busbar sections 31, 32, is also advantageously formed by conductor tracks that are present in all (here: 6) layers of the printed circuit board 10.The current-sensing resistor 33, which is mounted on the surface of the circuit board 10 and bridges the first busbar 20 without electrical contact, thus forms a further section of the second busbar 30, connecting the two busbar sections 31, 32 of the second busbar 30. Advantageously, the resistor 33 is thermally connected to both busbars 20, 30 due to its arrangement.

[0068] In the illustrated embodiment, it is provided that a current measurement signal conductor 41 or 42 branches off from each of the conductor tracks formed in the first layer, where the current measuring resistor 33 is electrically contacted (differential voltage measuring line), wherein one (41) of the two current measurement signal conductor tracks 41, 42, starting from the branch point, first passes under the current measuring resistor 33 and then runs parallel to the other (42) of the two current measurement signal conductor tracks 41, 42 leading out of the center of the intersection area (cf. Fig. 1 and Fig. 2) Advantageously, both current-measuring signal conductors 41, 42 run on the same side with respect to both the first conductor rail 20 and the second conductor rail 30 out of the crossing area. Since the current-measuring signal conductors 41, 42 do not carry any significant current, they can be designed with a very narrow width, as shown (compared to the widths of the conductors used to form the conductor rails 41, 42).

[0069] As it is in Fig. As can be seen in Figure 2, the conductor track of the first conductor rail 20 formed in the first layer is interrupted in the area of ​​the measuring line routing (current measurement signal conductor track 41) in order to realize the section of the current measurement signal conductor track 41 which passes under the current measurement resistor 33 in this area.

[0070] Furthermore, as it is in the Fig. 1 and Fig. As can be seen in Figure 2, in the illustrated example, the conductor tracks of the two busbars 20 and 30 formed in the first layer taper towards the center of the intersection area when viewed from above on the circuit board 10. In busbar 20, these tapers create a kind of "narrowing" of the conductor track width formed in the first layer (and interrupted below the resistor 33), with this narrowing or the contour of this conductor track being symmetrical to a center line of the conductor track's path. In the area of ​​the respective taper, one of the connecting tabs of the current-sensing resistor 33 is attached to each of the two busbar sections 31 and 32 of the second busbar 30.

[0071] As already explained, in the illustrated example, the first busbar section 31 and the second busbar section 32 of the second busbar 30 are each formed by conductor tracks extending through all (here: 6) layers of the printed circuit board 10, with the electrical current conduction of the two busbar sections 31, 32 being extended to all layers of the printed circuit board structure by means of the vias 35. The vias 35, or at least a portion thereof, provided for the electrical connection of the respective conductor tracks, can advantageously be arranged, for example, as shown, adjacent to or near the two contact areas of the current-sensing resistor 33, to which the terminals of the current-sensing resistor 33 are electrically connected.

[0072] Similarly, in this example, the first busbar 20 is formed by conductor tracks in all (here: 6) layers of the printed circuit board 10, whereby the electrical current conduction of the busbar 20 is extended to all layers of the printed circuit board structure by means of the vias 25. The vias 25, or at least some of them, provided for the electrical connection of the conductor tracks can advantageously be arranged, for example, as shown, in the intersection area of ​​the busbars 20, 30, and in particular extending into a region below the current-sensing resistor 33.

[0073] The electrical vias 25, 35 serve to distribute the current to be carried via the busbars 20, 30 as evenly as possible across all relevant layers of the printed circuit board 10. Furthermore, the vias 25, 35 advantageously reduce the temperature gradient between the opposing surfaces (top, bottom) of the printed circuit board 10 by correspondingly increasing the thermal conductivity of the printed circuit board 10 in the vertical direction.

[0074] In this example, the vias 25 and 35 are implemented as holes through the circuit board 10, the walls of which are plated with copper. Since the reduction in the cross-sectional area of ​​the conductors caused by the holes is partially compensated for by the copper plating, the vias 25 and 35 do not significantly increase the electrical resistance in the longitudinal direction of the respective busbar.

[0075] In the illustrated embodiment, it is provided that all of the illustrated vias 25, 35 extend continuously from the uppermost (first) layer of the printed circuit board to the lowermost layer of the printed circuit board, which is not mandatory but is particularly advantageous for achieving the aforementioned most uniform distribution of the current and the reduction of the temperature gradient.

[0076] Furthermore, it is advantageous if, in the intersection area, the vias 25 and 35 provided in each of the “4 areas” (on both sides of the first busbar 20 and on both sides of the second busbar 30) (and in particular, for example, extending from the top 12 to the bottom 14 of the circuit board 10) are arranged evenly distributed over the available area.

[0077] In particular, each such distribution can provide several (preferably at least 3, or at least 5) mounting locations distributed orthogonally to the relevant busbar direction. Alternatively or additionally, the distribution can also provide several (preferably at least 3, or at least 5) mounting locations distributed along the relevant busbar direction. Both are, for example, also shown in the example of the Fig. 1, Fig. 2 to Fig. 3 the case in which the respective vias 25 and 35 are arranged on a grid (here e.g. square grid).

[0078] In contrast to the exemplary embodiment according to the Fig. 1, Fig. 2 to Fig. 3. The top and / or bottom of the printed circuit board can be connected to an upper or lower heat sink, respectively. Examples are given below with reference to the... Fig. 4, Fig. 5 to Fig. 6 described.

[0079] In the following description of further embodiments, the same reference numerals are used for components with the same effect. Essentially, only the differences from the embodiment(s) already described are addressed, and otherwise, reference is expressly made to the description of the preceding embodiments.

[0080] Fig. Figure 4 shows a perspective sectional view of another example of a circuit arrangement similar to that of the example of Fig. 1, Fig. 2 to Fig. 3, but with a heat sink 50 on the underside of the circuit board 10. In this example, the circuit board surface (underside) opposite the current-sensing resistor 33 is cooled by means of the heat sink 50. The heat sink 50 can advantageously be attached, for example, by means of an electrically insulating thermally conductive material. In the example, a layer of thermally conductive material 70 is provided for this purpose.

[0081] Fig. Figure 5 shows a further example of a circuit arrangement similar to that of the example in a perspective sectional view. Fig. 1, Fig. 2 to Fig. 3, but with a heat sink 60 on the top side of the circuit board 10. In this example, the circuit board surface (top side) adjacent to the current-sensing resistor 33 is cooled by means of the heat sink 60. The heat sink 60 can advantageously be connected, for example, by means of an electrically insulating thermal conductivity material 70, as shown.

[0082] The heat sink 60 can be viewed from above on the circuit board 10 as shown in Fig. Figure 5 shows that the heat sink 60 extends, in particular, over an area in which the current-sensing resistor 33 is also located. In this example, the heat sink 60 is provided on its underside with a cavity into which the current-sensing resistor 33 projects or is received. The cavity is preferably also filled with an electrically insulating thermal conductivity material 70. Heat generated by the current-sensing resistor 33 is transferred via its surface to the thermal conductivity material 70 and then to the heat sink 60. In a preferred embodiment, an electrically insulating thermal conductivity material is also present between the resistor 33 (or its body) and the underlying surface of the circuit board 10.

[0083] Fig. Figure 6 shows a perspective sectional view of another example of a circuit arrangement similar to that of the example of Fig. 1, Fig. 2 to Fig. 3, however, with a heat sink 50 on the underside of the circuit board 10 and another heat sink 60 on the top side of the circuit board 10. In this example, both the circuit board surface opposite the current-sensing resistor 33 and the circuit board surface adjacent to or near the current-sensing resistor 33 are cooled by means of the respective heat sink 50 or 60. Each of the two heat sinks 50, 60 can advantageously be connected to the respective surface of the circuit board 10, for example, by means of an electrically insulating thermal interface material. The heat sink 60 can, for example, be constructed as in the previous example. Fig. 5 be formed and arranged, i.e. with a cavity filled with thermal conductivity material 70 for receiving and thus thermally connecting the current measuring resistor 33.

[0084] In summary, the invention and the described embodiments offer in particular the following advantages:By arranging the current-sensing resistor above the first busbar, combined with its distribution across several (especially all) layers of the printed circuit board, the thermal resistance between the resistor and its surroundings is advantageously and significantly reduced. In this respect, for example, the underside of the resistor's body can be thermally connected to the top side of the circuit board via an electrically insulating thermal interface material. This advantageously reduces the influence of temperature fluctuations on the voltage drop (measuring voltage) measured across the resistor for current measurement purposes. Such temperature fluctuations can be caused, for example, by fluctuations in ambient temperature, particularly in the mobile applications preferred here (e.g., power electronics in a vehicle, such as power converters).Furthermore, the current flowing through the current measuring resistor generates waste heat, which, if the current is not constant over time, leads to corresponding temperature fluctuations in the current measuring resistor.

[0085] The use of multiple layers, preferably all layers (i.e., utilization of the entire layer cross-section) of the printed circuit board for the first busbar also significantly reduces the electrical resistance of the first busbar, resulting in less power loss and thus reducing the overall power loss of the circuit arrangement. The same applies to the first and second busbar sections of the second busbar. This allows higher currents to be carried with comparable dimensions, and the dimensions of the circuit arrangement or printed circuit board can be reduced for comparable currents. The circuit arrangement according to the invention is therefore highly versatile and can be used in numerous devices and equipment with high operating currents, such as DC / DC converters, rectifiers, inverters, etc., particularly in mobile applications (e.g., in a vehicle). Reference symbol list 10 circuit boards 12 Top side (of the circuit board) 14 Underside (of the circuit board) 20 first busbar 25 vias 30 second busbar 31 first conductor rail section 32 second conductor rail section 33 Current measuring resistor 35 vias 41 Measuring line (conductor track) 42 Measuring leads (conductor track) 50 heat sinks (on top) 60 heat sinks (on the underside) 70 Thermal conductivity material

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