Device for measuring temperature and device for determining current

Description

TECHNICAL FIELD OF THE INVENTION

[0001] The invention relates to a device for temperature measurement, a device for current determination with a temperature measuring module and an electrical power converter with a current determination module. STATE OF THE ART

[0002] A precise measurement of the temperature of an object using a temperature sensor, for example, one with a temperature-dependent resistor, generally requires good thermal contact between the temperature sensor and the object being measured. The temperature sensor and associated evaluation electronics can be arranged on a circuit board, so that the temperature sensor is located between the circuit board and a surface of the object being measured during operation. However, this arrangement requires that the circuit board itself be spaced from the surface by at least the height of the temperature sensor.

[0003] Low-ohmic measuring resistors, so-called shunts, can be used to precisely determine electrical currents, especially high currents in the range of several kiloamperes. For example, DE 10 2016 010 012 B4 discloses a measuring arrangement for measuring a current in which pairs of voltage taps measure a voltage drop across a resistance element. A measuring circuit uses Ohm's law to determine a measure of the electrical current flowing through the resistance element from the dropped voltage and the resistance value of the resistance element. The resistance value of the resistance element is temperature-dependent, so a temperature sensor is arranged on the resistance element, and the measuring circuit adjusts the resistance value used to determine the current intensity depending on the temperature measured by the temperature sensor.

[0004] EP 3 620 799 A1 and EP 1 435 524 A1 disclose further devices for determining current, in which a voltage drop across a resistance element is measured, wherein additionally a temperature measurement and a calibration of the determination of the current intensity from the measured voltages as a function of the measured temperature are provided.

[0005] Especially when the resistance element is made of a common material with very good conductivity, such as copper, whose specific resistance is highly temperature-dependent, the temperature of the resistance material must be measured precisely where the relevant voltage drop occurs. A conventional arrangement of the temperature sensor on a side of a circuit board facing the resistance element allows for good thermal connection to the resistance element, but results in a distance between the circuit board and the resistance element that is at least on the order of magnitude of the height of the temperature sensor.

[0006] Additionally, it is desirable to position the connections between the voltage taps and the measuring circuit very close to the resistance element, especially to avoid conductor loops. Conductor loops, especially near high currents, can cause significant interference or measurement distortion due to electromagnetic effects, especially if the currents contain periodic or transient components.

[0007] To avoid such conductor loops, it is possible to place the temperature sensor on the side of the circuit board facing away from the resistance element, so that the circuit board with the connections between the voltage taps and the measuring circuit can be positioned as close as possible to the resistance element. However, this increases the thermal resistance between the temperature sensor and the busbar, as the heat flow from the resistance element must first penetrate and pass through the circuit board.

[0008] Another option would be to mount the temperature sensor on the side of the shunt opposite the circuit board (see DE 10 2016 010 012 B4). However, this requires additional connections between the temperature sensor and the measuring circuit, which run outside the circuit board and thus incur additional assembly effort and costs. Furthermore, for sufficiently accurate temperature measurement, the temperature sensor must be pressed against the surface being measured. However, this pressure must not be too high to avoid damaging the temperature sensor.

[0009] DE 10 2011 004 174 A1 discloses an electrical connection arrangement in which a printed circuit board has a height-flexible circuit board area in which an electronic component can be arranged. The component is mechanically connected to a functional unit and thus fixed in position. The mechanical connection to the functional unit can be improved by additional spring elements between the printed circuit board and the component. OBJECT OF THE INVENTION

[0010] The invention is based on the object of providing a device for temperature measurement which ensures good thermal contact of a temperature sensor with the surface of an object to be measured, as well as a device for current determination in which a voltage drop across a resistance element with a temperature-dependent resistance value can be measured undisturbed, the current being determined from the voltage drop and a resistance value which is adapted by means of an exact measurement of the temperature of the resistance element. SOLUTION

[0011] The object is achieved by a device for current detection with a shunt as defined in claim 1. DESCRIPTION OF THE INVENTION

[0012] A temperature measurement device comprises a printed circuit board, an evaluation unit, and a temperature sensor. The printed circuit board has a milled recess that runs essentially spirally around the temperature sensor, allowing the temperature sensor to be arranged on a printed circuit board plateau and displaceable parallel to the normal vector of the plane of the printed circuit board. When the temperature sensor is displaced relative to the plane of the printed circuit board, a restoring force acts between the printed circuit board and the temperature sensor.

[0013] The temperature measuring device is particularly advantageously suited to being placed directly on the surface of an object whose temperature is to be measured by the temperature sensor. The temperature sensor can be arranged on a circuit board plateau that is located in the center of the spiral milled cutout and thus at the inner end of the remaining circuit board web formed by the milled cutout. When the circuit board is placed flush with the surface of the object to be measured with the temperature sensor between the circuit board and the surface, the circuit board plateau is pressed out of the plane of the circuit board by the height of the temperature sensor, so that both the circuit board itself and the temperature sensor can rest on the surface. This particularly simplifies the installation of the temperature measuring device on the surface of the object to be measured.

[0014] The temperature sensor is preferably spring-mounted by a printed circuit board web remaining between the turns of the spiral-shaped cutout. The remaining printed circuit board web, which is also spiral-shaped, creates a spring effect on the printed circuit board plateau and thus on the temperature sensor when the printed circuit board plateau is moved out of the plane of the printed circuit board. This occurs in particular when the printed circuit board is placed flat on the surface of the object to be measured and the cutout, which runs around the temperature sensor, ensures height compensation so that the temperature sensor is moved parallel to the normal vector of the plane of the printed circuit board. The temperature sensor can be displaceable by a spring travel that covers at least its overall height.

[0015] The cutout in the circuit board can preferably extend along a continuous spiral shape. The spiral shape can comprise a plurality of essentially straight sections and changes in direction between the sections, wherein the changes in direction particularly result in a substantially right angle between the sections. The changes in direction themselves can be continuous, for example, comprising a quarter circle. A continuous spiral shape, in particular, is particularly easy to produce in a single step and has a readily reproducible restoring force when the circuit board plateau is displaced out of the circuit board plane.

[0016] The milling can be configured such that a radius vector of the milling trajectory sweeps an angle of at least 600 degrees, preferably at least 700 degrees, so that the remaining circuit board land surrounds the temperature sensor at least three-quarters of its length, preferably at least once. As a result, a displacement of the circuit board plateau by the height of the temperature sensor out of the circuit board plane leads to an elastic deformation of the remaining circuit board land, which is certainly below the limit for plastic deformation of the circuit board material, so that the restoring force of the circuit board land is permanently maintained and is not significantly reduced even under the influence of temperatures above 100 degrees Celsius.

[0017] In a design with straight sections, the number of straight sections can be selected so that the sum of the angles of the changes of direction between the straight sections reaches the aforementioned degrees. For example, in the case of right-angled changes of direction, more than six sections must be provided.

[0018] In one embodiment of the device, the width of the circuit board land, the width of the cutout, and the length of the cutout can be designed such that the restoring force between the circuit board and the temperature sensor is between 0.1 and 10 Newtons, preferably between 1 and 5 Newtons, when the temperature sensor is displaced by its overall height parallel to the normal vector of the plane of the circuit board. As a result, when the circuit board and the temperature sensor rest flat on the surface of the object to be measured, a force acts on the temperature sensor that ensures reliable thermal contact between the temperature sensor and the surface. Specifically, the circuit board can have a thickness between 0.5 and 3 millimeters, while the cutout and the remaining circuit board land can each have a width between 0.3 and 3 millimeters.

[0019] In an advantageous embodiment, the outer edge of the cutout encloses an area that is less than 200 square millimeters, preferably less than 100 square millimeters. This allows the use of a temperature sensor with a small housing that occupies essentially the entire surface of the circuit board plateau, whereby any peripheral components on the circuit board can be arranged very close to the temperature sensor, in particular on the side of the circuit board level facing away from the temperature sensor.

[0020] To connect the temperature sensor to an evaluation unit, electrical conductor tracks can run along the remaining PCB bridge. The conductor tracks can have a width between 50 and 1000 micrometers and be spaced between 50 and 1000 micrometers apart. This eliminates the need for external contact with the temperature sensor via wires, cables, or similar.

[0021] The temperature sensor can be designed as a passive component connected to the evaluation unit via at least two conductor tracks. Alternatively, the temperature sensor can be designed as an active component and connected to the evaluation unit via at least three conductor tracks.

[0022] In one embodiment of the device, the temperature sensor can be arranged on a first side of the circuit board and the evaluation unit on a second side of the circuit board, so that the evaluation unit is arranged on the side of the circuit board opposite the temperature sensor. In particular, the first side of the circuit board can essentially exclusively have the temperature sensor, while all other components are arranged on the second side, opposite the temperature sensor. This particularly advantageously enables the first side of the circuit board with the spring-mounted temperature sensor to rest flush with the surface of the object to be measured. The conductor tracks between the temperature sensor and the evaluation unit can have vias through the circuit board.

[0023] In an alternative embodiment, the temperature sensor and the evaluation unit can be arranged on the same side of the circuit board. This allows a thermal connection between the underside of the temperature sensor and the surface of the object to be measured to be established via the circuit board, whereby the circuit board can be optimized for thermal conductivity at the location of the temperature sensor.

[0024] A current-detecting device comprises a shunt and a temperature-measuring device as described above. The shunt has two connection regions and a resistance region with a substantially flat surface located electrically between the connection regions. The current-detecting device is arranged in the resistance region on the surface of the shunt such that the temperature sensor is arranged in thermal connection with the resistance region of the shunt. Voltage taps are arranged on both sides of the temperature sensor, which electrically contact the surface of the shunt to detect a potential difference along the resistance region.

[0025] In one embodiment of the device, the circuit board rests flat on the shunt so that the voltage taps are electrically connected to the surface of the shunt and the temperature sensor rests on the surface of the shunt. In the assembled state of the device, the temperature sensor is offset from the plane of the circuit board by its overall height so that the remaining circuit board web exerts a restoring force on the circuit board plateau and thus a contact force on the temperature sensor. This embodiment optimally meets the essential requirements of the device for current detection by placing the temperature sensor directly on the resistance area and optimally thermally connecting it to the resistance material through the spring action of the remaining circuit board web, so that a temperature measurement with high accuracy can be achieved.Additionally, the temperature sensor can be placed in the center of the resistance section and centrally between the voltage taps, so that the temperature is measured in precisely the same area where the voltage drop due to a current flowing through the shunt is also measured. This allows temperature-related changes in the resistance of the material in the resistance section of the shunt to be optimally compensated for when determining the current flowing through the shunt. At the same time, the circuit board rests largely flush with the surface of the resistance section, so that the conductor tracks in the circuit board that connect the voltage taps to a measuring circuit for determining the voltage drop between the voltage taps also lie close to the surface of the resistance section, largely avoiding conductor loops during voltage measurement.

[0026] In an alternative embodiment of the device, the temperature sensor and the evaluation unit are arranged on the side of the circuit board opposite the shunt. The circuit board plateau is mechanically connected to the surface of the shunt, wherein the circuit board plateau is displaceable relative to the plane of the circuit board. In particular, the side of the circuit board plateau opposite the temperature sensor can be connected to the shunt, in particular by means of an adhesive. Any offset between the plane of the circuit board and the surface of the shunt at the location of the circuit board plateau is compensated for by displacing the circuit board plateau, and thus the temperature sensor, by the offset relative to its rest position in the plane of the circuit board.This embodiment also optimally meets the requirements of the device for current detection, since the temperature sensor, in particular with its underside, is optimally thermally connected to the resistance material via the circuit board plateau and remains so even if the position of the circuit board relative to the surface of the shunt should change.

[0027] The thermal connection of the underside of the temperature sensor can be further improved by incorporating a heat conductor into the circuit board plateau, for example, a metallic insert or several at least partially interconnected copper layers. Assuming that the circuit board is arranged as flush as possible with the shunt, thermal and electromechanical effects acting on the shunt at high operating currents can cause deformation of the shunt and / or the circuit board, leading to at least partial detachment of the circuit board from the shunt. This does not affect the thermal connection of the temperature sensor to the shunt, as the circuit board plateau is mechanically firmly connected to the shunt and compensates for the offset between the plane of the circuit board and the surface of the shunt.

[0028] Specifically, the voltage taps can be arranged symmetrically around the temperature sensor and can be designed either as press-fit pins in the circuit board and / or in the shunt, as spring contacts, as soldered connections or as screw connections with the shunt.

[0029] In one embodiment, the shunt can be designed to conduct currents with a current intensity of more than 100 amperes, preferably more than 1000 amperes. The shunt can be formed integrally from a single material, with the resistance region essentially formed by a tapered cross-section compared to the cross-section of the shunt's connection areas. This avoids material transitions and reduces manufacturing and assembly costs.

[0030] Alternatively, the resistance region of the shunt can be made of a different material than the connection regions, for example, a material with different electrical properties, and optionally include a tapered cross-section of the shunt. Further improved current measurement accuracy can be achieved by knowing the electrical properties of the material in the resistance region more precisely than those of the connection region material, particularly with regard to the temperature dependence of the resistivity of the material in the resistance region. It is not absolutely necessary to use a material with a particularly low temperature dependence of the resistivity in the resistance region of the shunt; rather, it is sufficient to know and / or determine the temperature dependence as precisely and reproducibly as possible.

[0031] In one embodiment, the tapering of the shunt's cross-section in the resistance region may involve reducing the cross-section to a value between 10 and 60 percent of the cross-section of the shunt's terminal regions. This results in a higher current density in the resistance region than in the shunt's terminal regions, which in turn results in a higher voltage drop for a given current flowing through the shunt. While this locally increased current density is accompanied by an increased temperature in the resistance region, this effect is neutralized by temperature compensation based on the temperature measurement representative of the resistance region and overcompensated by confinement to a locally limited and well-defined measurement range.

[0032] To avoid any unwanted electrical contact, an electrically insulating foil can be arranged between the temperature sensor and the surface of the shunt.

[0033] A power converter has current-carrying lines for conducting the direct and / or alternating currents processed by the power converter. At least one of the current-carrying lines comprises a device for current detection according to the preceding description, wherein the device bridges an interruption in the current-carrying lines or is integrated into the current-carrying lines. The power converter is configured to determine a current flowing through the current-carrying lines during operation of the power converter from a potential difference detected by the voltage taps along the resistance range of the shunt and a resistance value of the resistance range. The resistance value used to calculate the current intensity is a function of the temperature detected by the temperature sensor.

[0034] In a preferred embodiment, the power converter is designed for a rated power greater than 10 kW, preferably greater than 100 kW, and particularly preferably greater than 1000 kW. In these power classes, determining the direct and / or alternating currents processed by the power converter is particularly challenging due to their correspondingly high amplitudes and can be performed particularly accurately using the described current-determining device. The described current-determining device can be integrated particularly easily into the design of the power converter. BRIEF DESCRIPTION OF THE CHARACTERS

[0035] In the following, the invention is further explained and described with reference to embodiments shown in the figures. Fig. 1 shows a device for temperature measurement, Fig. 2 shows a device for current detection, Fig. 3 shows a cross section through an embodiment of the device for current detection, and Fig. 4 shows a cross section through a further embodiment of the device for current detection. FIGURE DESCRIPTION

[0036] Fig. 1shows a temperature measuring module 1 as an embodiment of a temperature measuring device according to the application. The temperature measuring module 1 comprises a printed circuit board 2. A temperature sensor 3 is arranged on the printed circuit board 2. A cutout 4 in the printed circuit board 2 runs around the temperature sensor 3. The cutout 4 can be introduced into the printed circuit board 2 before the components are populated or subsequently after the components have been populated. The cutout 4 runs essentially spirally around the temperature sensor 3, leaving a printed circuit board web 5 that is bordered on both sides by the cutout 4 and also runs essentially spirally.

[0037] The spiral shape along which the milling 4 runs can be designed in different ways; in particular, it can have essentially straight sections and essentially right-angled changes in direction (cf. Fig. 1), or it can be composed of arc segments with different radii. It is also conceivable to provide non-rectangular changes of direction. It goes without saying that, for manufacturing reasons, certain minimum radii are always unavoidable when milling out a change of direction. Therefore, a change of direction usually comprises an arc; in the case of a 90-degree bend, this can in particular be a quarter circle. Thus, the milling 4 can be manufactured cost-effectively in one go, and in particular using a standard tool.

[0038] At the end of the remaining circuit board web 5 is a circuit board plateau 2a, on which the temperature sensor 3 is arranged. The circuit board plateau 2a is completely surrounded by the cutout 4. In addition, the remaining circuit board web 5 runs once around the circuit board plateau 2a. A radius vector of the trajectory of the cutout 4, i.e. a vector from the center of the circuit board plateau 2a to a point of the cutout 4, runs approximately twice around the temperature sensor 3, i.e. it sweeps from the beginning to the end of the cutout 4 according to Fig. 1 an angle of approximately 700 degrees. In alternative embodiments, the cutout 4 can also be shorter and, for example, only encircle the temperature sensor 3 one and a half or one and three-quarters of a time, corresponding to an angle of approximately 500 degrees or 600 degrees, respectively.

[0039] The temperature measurement module 1 further comprises an evaluation unit 7. The evaluation unit 7 can be arranged on the same side of the circuit board 2 as the temperature sensor 3 or on the opposite side. The temperature sensor 3 is connected to the evaluation unit 7 via conductor tracks 6. The conductor tracks 6 run along the remaining circuit board web 5.

[0040] The temperature sensor 3 can be designed as an active or passive component. An active temperature sensor 3 must generally be connected to the evaluation unit 7 via at least three lines, while a passive temperature sensor 3 is connected to the evaluation unit 7 via two to four lines. Accordingly, the conductor tracks 6 comprise a suitable number of individual lines that run next to one another or one above the other in the remaining circuit board web 5. When using an active component as the temperature sensor 3, the evaluation unit 7 can also be arranged outside the circuit board 2, e.g., on another assembly, so that the temperature sensor 3 can be connected to a suitable programmable logic or a microcontroller via the conductor tracks 5 and additional cabling.

[0041] Fig. 2shows a device for current detection with a current detection module 10 and a shunt 11. In this example, the shunt 11 is formed in one piece and comprises connection areas 11a and a resistance area 11b. The connection areas 11a are designed here for connection to a busbar, which is, for example, part of a power converter and transports high direct currents or alternating currents. For this purpose, the shunt 11 can bridge an interruption in the busbar or even form the busbar itself, for example by connecting an input terminal or a semiconductor circuit of the power converter to one end of the shunt 11 and / or an inductance or a relay to the other end of the shunt 11. Alternatively or additionally, the connection areas 11a can be used for connection to other types of current-carrying lines, e.g.Cables and have connecting elements 14 for electrical and / or mechanical connection to adjacent components. In principle, the resistance region 11b can also be integrated into a current-carrying line in such a way that the connection regions 11a merely indicate the electrical contacts of the resistance region 11b with adjacent components.

[0042] The current detection assembly 10 has a device for temperature measurement according to Fig. 1 with a circuit board 2, a temperature sensor 3 and a cutout 4 running around the temperature sensor 3. The temperature sensor 3 can be arranged on the side of the circuit board 2 facing the shunt 11, ie between the circuit board 2 and the surface of the resistance area 11b, compare Fig. 3. The temperature sensor 3 can also be arranged on the side of the circuit board 2 opposite the shunt 11, ie on the same side as the evaluation unit 7, compare Fig. 4 . In addition, the current detection assembly 10 has two voltage taps 12, which are arranged upstream and downstream of the temperature sensor 3 along the flow direction of the current I and are electrically connected to the surface of the resistance region 11b. The voltage taps 12 are connected to a voltmeter 13, which detects a voltage difference between the potentials on the surface of the resistance region 11b at the positions of the voltage taps 12.

[0043] An evaluation unit (not shown here), which can be combined with the evaluation unit 7 or implemented separately, can determine the amplitude of a current I flowing through the shunt 11 based on Ohm's law from the measured values ​​of the voltmeter 13 and the electrical resistance of the resistance region 11b. The electrical resistance of the resistance region 11b is generally temperature-dependent. Therefore, the electrical resistance used to calculate the current intensity is specified as a function of the temperature of the resistance region 11b determined by the temperature sensor 3.

[0044] The resistance region 11b has a cross-section that is smaller than the cross-section of the connection regions 11a. This increases the current density of a current I flowing through the shunt 11 in the resistance region 11b. Since the shunt 11 itself is optimized for the lowest possible losses, an increase in the current density is advantageous in order to generate a voltage difference between the voltage taps 12 that is high enough to be safely within the measuring range of the voltmeter 13. Alternatively or in addition to the tapering of the cross-section according to Fig. 2 the resistance region 11b may have a different material composition than the connection regions 11a, for example a material with a (slightly) increased electrical resistance and / or a reduced temperature dependence of the electrical resistance.

[0045] Fig. 3 shows a cross section through the device for current determination according to Fig. 2at the level of the resistance region 11b. The printed circuit board 2 lies flush with the surface of the shunt 11. The temperature sensor 3 is arranged on the side of the printed circuit board 2 facing the shunt 11, i.e. between the printed circuit board 2 and the surface of the resistance region 11b, and also lies on the surface of the resistance region 11b. As a result, the temperature sensor 3 has shifted by its overall height 8a relative to its rest position in the unassembled state of the printed circuit board 2 relative to the plane of the printed circuit board 2, in that the printed circuit board plateau 2a is offset by the overall height 8a parallel to the normal vector of the plane of the printed circuit board 2. This is possible because the printed circuit board plateau 2a is only connected to the rest of the printed circuit board 2 by the remaining printed circuit board web 5.The offset of the circuit board plateau 2a by the overall height 8a is thus distributed over an elastic deformation of the entire circuit board web 5 with a moderate gradient relative to the plane of the circuit board 2.

[0046] The elastic deformation of the circuit board web 5 causes a restoring force that presses the temperature sensor 3 onto the surface of the resistance region 11b. At the same time, the voltage taps 12 are pressed onto the surface of the resistance region 11b by the circuit board 2 itself, thus bringing them into electrical contact. Alternatively or additionally, the voltage taps 12 can also themselves establish the mechanical connection between the circuit board 2 and the shunt 11, for example, by the voltage taps 11 being designed as press-in contacts that are pressed into corresponding holes in the circuit board 2 and the surface of the shunt 11. Other electrical and / or mechanical contacting of the voltage taps 12 with the resistance region 11b is also conceivable, for example via spring pins, screw or solder connections, or the like.

[0047] The offset of the circuit board plateau 2a enabled by the cutout 4 allows, in particular, the flush arrangement of the circuit board 2 on the resistance area 11b, even though the temperature sensor 3 is arranged between the circuit board 2 and the surface of the shunt 11. As a result, the electrical connections necessary for measuring the voltage drop between the voltage taps 12, in particular the lines between the voltage taps 12 and the voltmeter 13, can run in the immediate vicinity of the surface of the resistance area 11b, and in this regard, disadvantageous conductor loops, in particular those oriented perpendicular to the surface of the shunt 11, can be largely minimized.

[0048] Fig. 4 shows a cross section through a further embodiment of the device for current determination according to Fig. 2at the level of the resistance region 11b. The temperature sensor 3 is arranged on the side of the circuit board 2 opposite the shunt 11, i.e. on the same side as the evaluation unit 7. The circuit board plateau 2a, on which the temperature sensor 3 is arranged, rests on the surface of the resistance region 11b and is mechanically connected to the shunt 11, for example by means of an adhesive 9a, which can be designed as a thermally conductive adhesive and optimized for high thermal conductivity. A heat conductor 9b can be arranged in the circuit board plateau 2a, for example a copper inlay or several at least partially interconnected copper layers, whereby the thermal connection between the underside of the temperature sensor 3 and the side of the circuit board plateau 2a facing the shunt 11 is improved.

[0049] The printed circuit board 2 can have a certain offset 8b from the surface of the shunt 11. This offset can be deliberately chosen, for example for design reasons. An offset of the plane of the printed circuit board 2 from the surface of the shunt 11 can also be minimized at the time of production, in particular by the printed circuit board lying flat on the shunt 11; after assembly, however, an additional offset can arise, in particular at the location of the printed circuit board plateau 2a, e.g. if the shunt 11 and / or the printed circuit board 2 should deform. An inherently undesirable deformation of the shunt 11 can arise, for example, due to the application of mechanical force during assembly or transport as well as due to thermal expansion and / or electromagnetic forces occurring during operation, in particular if the shunt 11 is mechanically fixed in the connection areas 11a by means of the connecting elements 14.

[0050] Due to the mechanical connection of the circuit board plateau 2a to the shunt 11, the temperature sensor 3 is displaced parallel to the normal vector of the plane of the circuit board 2, by the same amount as the actual offset between the circuit board 2 and the surface of the shunt 11 at the location of the circuit board plateau 2a. This is possible because the circuit board plateau 2a is only connected to the rest of the circuit board 2 by the remaining circuit board web 5. The offset of the circuit board 2 relative to the surface of the shunt 11 is distributed over an elastic deformation of the entire circuit board web 5 with a moderate gradient relative to the plane of the circuit board 2. The offset generates a restoring force between the fixed circuit board level 2a and the circuit board 2, so that the circuit board 2 is pulled by the circuit board web 5 in addition to the shunt 11.In addition, the circuit board bridge 5 allows compensation of any lateral offset of the circuit board 2 compared to a nominal installation position.

[0051] In this case, the voltage taps 12 are electrically and mechanically connected to the resistance area 11b, for example via press-in contacts, spring pins, screw, plug or solder connections or the like.

[0052] The cutout 4 thus allows for offsetting of the printed circuit board 2 while simultaneously ensuring the thermal connection between the temperature sensor 3 and the resistance region 11b. This allows for a certain degree of deformation of the shunt 11 during operation to be tolerated. Alternatively or additionally, the requirements for the dimensional stability of the shunt 11 can be reduced depending on the thermal and / or mechanical boundary conditions, for example, by making the shunt 11 thinner overall and correspondingly more cost-effective.

[0053] In the embodiment according to Fig. 4 The underside of the temperature sensor 3 is thermally connected to the resistance region 11b of the shunt 11 via the circuit board plateau 2a. The temperature sensor 3 can be decoupled from the surrounding air by means of a hood, so that the top side of the temperature sensor 3 is not affected by any air flow above the circuit board 2, but is largely in thermal equilibrium exclusively with the resistance region. This further improves the measurement of the temperature of the resistance region. LIST OF REFERENCE SYMBOLS

[0054] 1Temperature measurement module 2PCB 2aPCB plateau 3Temperature sensor 4Cutout 5PCB bridge 6Conductor tracks 7Evaluation unit 8aHeight 8bOffset 9aAdhesive 9bHeat conductor 10Current detection module 11Shunt 11aConnection area 11bResistance area 12Voltage tap 13Voltmeter 14Connecting elements

Claims

1. A device for determining current, with a shunt (11), a printed circuit board (2), an evaluation unit (7) and a temperature sensor (3), the shunt comprising a resistance region (11b) with a substantially planar surface, the device for determining current being arranged in the resistance region (11b) on the surface of the shunt (11) in such a way the temperature sensor (3) is arranged in thermal connection with the resistance region (11b) of the shunt (11), wherein voltage taps (12) are arranged on either side of the temperature sensor (3) and making electrical contact with the surface of the shunt (11) in order to detect a potential difference along the resistance region (11b), wherein the printed circuit board (2) comprises a milled-out section (4) which runs essentially in a spiral around the temperature sensor (3), such that the temperature sensor (3) is arranged on a printed circuit board plateau (2a) and is spring-mounted by a printed circuit board web (5) remaining between the turns of the spiral milled-out section (4), wherein the temperature sensor (3) is displaceable parallel to the normal vector of the plane of the printed circuit board (2) and a restoring force acts between the printed circuit board (2) and the temperature sensor (3) by means of the printed circuit board web (5) when the temperature sensor (3) is displaced relative to the plane of the printed circuit board (2).

2. The device according to claim 1, wherein the printed circuit board (2) rests flat on the shunt (11) such that the voltage taps (12) are in electrical contact with the surface of the shunt (11) and the temperature sensor (3) rests on the surface of the shunt (11), wherein the temperature sensor (3) is displaced relative to the plane of the printed circuit board (2) by its overall height (8a), such that the remaining printed circuit board web (5) exerts a restoring force on the printed circuit board plateau (2a) and thus a contact pressure on the temperature sensor (3).

3. The device according to claim 1, wherein the temperature sensor (3) and the evaluation unit (7) are arranged on the side of the printed circuit board (2) opposite the shunt (11), wherein the printed circuit board plateau (2a) is mechanically connected to the surface of the shunt (11), wherein the printed circuit board plateau (2a) is displaceable relative to the plane of the printed circuit board (2) and compensates for an offset between the plane of the printed circuit board (2) and the surface of the shunt (3) at the location of the printed circuit board plateau (2a).

4. The device according to claim 3, wherein the printed circuit board plateau (2a) comprises a heat conductor (9b) for producing the thermal connection between the temperature sensor (3) and the resistance region (11b).

5. The device according to one of the preceding claims, wherein electrical conductor tracks (6) for making contact between the temperature sensor (3) and the evaluation unit (7) run along the remaining printed circuit board web (5).

6. The device according to one of the preceding claims, wherein the voltage taps (12) are realized as press-fit pins in the printed circuit board (2), as spring contacts, as solder connections, or as screw connections with the shunt (11).

7. The device according to one of the preceding claims, wherein the shunt (11) is designed for conducting currents whose amplitude is more than 100 amperes, preferably more than 1000 amperes.

8. The device according to one of the preceding claims, wherein the shunt (11) has two terminal regions (11a), wherein the resistance region (11b) is arranged between the terminal regions (11a) and is essentially formed by a tapering of the cross section with respect to the cross section of the terminal regions (11a) of the shunt (11).

9. The device according to one of the claims 1 to 7, wherein the shunt (11) has two connection areas (11a), wherein the resistance area (11b) is arranged between the connection areas (11a) and is made of a different material than the connection areas (11a) and optionally comprises a tapering of the cross-section of the shunt (11).

10. The device according to one of the preceding claims, wherein the tapering comprises a reduction of the cross section to a value between 10 and 60 percent of the cross section of the connection areas (11a) of the shunt (11).

11. The device according to claim 2, wherein an electrically insulating film is arranged between the temperature sensor (3) and the surface of the shunt (11).

12. The device according to claim 3 or 4, wherein the printed circuit board plateau (2a) is mechanically connected to the surface of the shunt (11) by means of an adhesive (9a)13. Power converter with current-carrying lines for conducting the direct currents and / or alternating currents processed by the power converter, wherein at least one of the current-carrying lines comprises a device for determining current in accordance with one of claims 1 to 12, which bridges an interruption in the current-carrying lines or is integrated into the current-carrying lines, wherein the power converter is configured to determine a current flowing through the current-carrying lines during operation of the power converter from a potential difference, detected by means of the voltage taps (12), along the resistance region (11b) of the shunt (11), and from a resistance value of the resistance region (11b), the resistance value being a function of the temperature detected by the temperature sensor (3).

14. The power converter according to claim 13, wherein the power converter is designed for a nominal power which is greater than 10 kW, preferably greater than 100 kW, particularly preferably greater than 1000 kW.