Current identification device

Abstract

The present invention relates to a temperature measurement device including a circuit board (2) and a temperature sensor (3), where the circuit board (2) has a milled groove (4) extending approximately helically around the temperature sensor (3), and the temperature sensor (3) is movable parallel to a normal vector to the plane of the circuit board (2), and movement of the temperature sensor (3) relative to the plane of the circuit board (2) results in a restoring force between the circuit board (2) and the temperature sensor (3). This device can be part of a current-determining device that uses, for example, a shunt, and measure its temperature. The present invention also relates to a power converter including this type of device.

Description

Technical Field

[0001] The present invention relates to a temperature measurement device, a current identification device having a temperature measurement assembly, and a power converter having a current identification assembly.

Background Art

[0002] In order to accurately measure the temperature of an object using a temperature sensor such as a temperature-dependent resistor, generally, it is necessary that the thermal contact between the temperature sensor and the object to be measured is good. In this case, the temperature sensor and the related evaluation electronic unit can be arranged on a printed circuit board, and the temperature sensor can be arranged between the printed circuit board and the surface of the object to be measured during operation. However, in this arrangement, it is necessary to arrange the printed circuit board itself at least at a distance corresponding to the overall height of the temperature sensor from the above surface.

[0003] A measuring resistor with low resistance, so-called shunt, can be used to accurately measure a high current in the region of several kiloamperes, especially current. For example, a measuring device for measuring current is known from DE102016010012B4. In this case, a pair of voltage taps measures the voltage drop between both ends of a resistance element, and a measuring circuit obtains a measured value of the current flowing through the resistance element from the voltage drop and the resistance value of the resistance element based on Ohm's law. Since the resistance value of the resistance element depends on temperature, a temperature sensor is arranged on the resistance element, and the measuring circuit adjusts the resistance value used to obtain the current intensity as a function of the temperature measured by the temperature sensor.

[0004] In particular, when the resistance element is made of a common material having very good conductivity such as copper, but its resistivity strongly depends on temperature, it is necessary to accurately measure the temperature of the resistance material at the position where the related voltage drop occurs. As conventionally known, arranging a temperature sensor on the side of the printed circuit board facing the resistance element enables good thermal connection with the resistance element, but a distance of at least about the overall height of the temperature sensor is formed between the printed circuit board and the resistance element.

[0005] Furthermore, to avoid conductor loops in particular, it is desirable to place the connection between the voltage tap and the measurement circuit very close to the resistive element. Conductor loops can cause significant interference and distortion in measurements due to electromagnetic effects, especially near high currents, if the current contains periodic or transient components.

[0006] To avoid such conductive loops, placing the temperature sensor on the side of the printed circuit board opposite the resistive element allows the printed circuit board containing the connection between the voltage tap and the measurement circuit to be positioned as close to the resistive element as possible. However, in this case, the heat flow from the resistive element must first enter the printed circuit board and pass through the board, resulting in increased thermal resistance between the temperature sensor and the busbar.

[0007] Another possibility is to mount the temperature sensor on the shunt side opposite the printed circuit board (see DE102016010012B4 again). However, this requires an additional connection between the temperature sensor and the measuring circuit, which extends outside the printed circuit board, resulting in additional assembly work and cost. Furthermore, to obtain a sufficiently good temperature measurement, the temperature sensor needs to be pressed firmly against the surface being measured, but the pressure should not be too high so as not to damage the temperature sensor.

[0008] DE102011004174A1 describes an electrical connection device in which a printed circuit board has a height-flexible printed circuit board area on which electronic components can be arranged. The components are mechanically connected to a functional unit and fixed in place, and the mechanical connection to the functional unit is improved by adding a spring element between the printed circuit board and the components. [Overview of the project]

[0009] Problems of the present invention The object of the present invention is to provide a temperature measuring device that ensures good thermal contact of a temperature sensor with the surface of an object to be measured, and to present a current determination device that can measure the voltage drop across a resistive element having a temperature-dependent resistance value without interference, and from the voltage drop and the resistance value adjusted by accurately measuring the temperature of the resistive element, the current can be determined.

[0010] solution This objective is achieved by a temperature measuring device having the features of claim 1, a current identifying device having the features of independent claim 14, and a power converter as described in claim 22. Preferred embodiments are provided in the dependent claims.

[0011] Description of the present invention The temperature measuring device comprises a printed circuit board, an evaluation unit, and a temperature sensor. The printed circuit board has a milled groove that extends substantially spirally around the temperature sensor, thereby positioning the temperature sensor on the plateau of the printed circuit board and allowing it to be displaced 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 is generated between the printed circuit board and the temperature sensor.

[0012] Temperature measuring devices are particularly advantageous for being placed directly on the surface of an object whose temperature is to be detected by the temperature sensor. For this purpose, the temperature sensor can be placed on a printed circuit board plateau, which is located in the center of a helical milled groove and thus on the inner edge of the remaining printed circuit board web formed by the milled groove. When the printed circuit board is placed coplanar with the surface of the object to be measured, and the temperature sensor is placed between the printed circuit board and the surface, the printed circuit board plateau is pushed out from the plane of the printed circuit board by the height of the temperature sensor, so that both the printed circuit board itself and the temperature sensor can be placed in contact with the surface. This simplifies the mounting of the temperature measuring device to the surface of the object to be measured.

[0013] The temperature sensor is preferably mounted spring-loaded by a printed circuit board web remaining between turns of a helical milled groove. Similarly, the helical remaining printed circuit board web creates a spring effect on the printed circuit board plateau, and thereby on the temperature sensor, when the plateau moves outside the plane of the printed circuit board. This is particularly true when the printed circuit board is placed flat on the surface of the object being measured, and the milled grooves extending around the temperature sensor provide height compensation so that the temperature sensor moves parallel to the normal vector of the plane of the printed circuit board. Thus, the temperature sensor is displaceable by a spring stroke that includes at least its total height.

[0014] Preferably, the milled grooves of the printed circuit board can extend along a continuous helical shape. In this case, the helical shape can include a number of substantially linear sections and changes of direction between those sections, where the changes of direction form, for example, substantially right angles between those sections, and in this case the changes of direction themselves are continuous, i.e., can include, for example, quarter circles. In particular, a continuous helical shape is especially easy to manufacture in one go, and it is possible to easily reproduce the restoring force when the printed circuit board plateau is displaced outside the plane of the printed circuit board.

[0015] The milled groove can be formed such that the radial vector of the groove's trajectory sweeps over an angle of at least 600 degrees, preferably at least 700 degrees, so that the remaining printed circuit board web extends at least 3 / 4 of a turn, preferably at least 1 turn, around the temperature sensor. As a result, when the printed circuit board plateau is displaced by the height of the temperature sensor from the plane of the printed circuit board, the remaining printed circuit board web elastically deforms, which safely stays below the limit of plastic deformation of the printed circuit board material. Consequently, the restorative force of the printed circuit board web is permanently maintained and does not significantly decrease even under the influence of temperatures above 100°C.

[0016] In designs with straight sections, the number of straight sections can be selected such that the sum of the angles of direction changes between the straight sections reaches the aforementioned degree. For example, if the direction changes at right angles, seven or more sections are required.

[0017] In one embodiment of this device, the width of the printed circuit board web, the width of the milled groove, and the length of the milled groove can be set such that when the temperature sensor is displaced by its total height parallel to the normal vector of the plane of the printed circuit board, the restoring force between the printed circuit board and the temperature sensor is 0.1 to 10 Newtons, preferably 1 to 5 Newtons. As a result, when the printed circuit board and temperature sensor are placed flat on the surface of the object to be measured, a force acts on the temperature sensor to ensure reliable thermal contact between the temperature sensor and the surface. For example, the printed circuit board may have a thickness of 0.5 to 3 millimeters, while the milled groove and the remaining printed circuit board web may each have a width of 0.3 to 3 millimeters.

[0018] In an advantageous embodiment, the outer edge of the milled groove surrounds an area smaller than 200 square millimeters, preferably smaller than 100 square millimeters. This allows for the use of a temperature sensor with a small housing that occupies substantially the entire area of ​​the printed circuit board plateau, and allows peripheral components on the printed circuit board to be placed very close to the temperature sensor, particularly on the side of the printed circuit board opposite the temperature sensor.

[0019] To bring the temperature sensor into contact with the evaluation unit, electrical conductor tracks can be extended along the remaining printed circuit board web. These conductor tracks can have a width of 50 to 1000 micrometers and be spaced 50 to 1000 micrometers apart from one another. This eliminates the need to bring the temperature sensor into external contact, particularly via wires, cables, etc.

[0020] The temperature sensor can be implemented as a passive component connected to the evaluation unit via at least two conductor tracks. Alternatively, the temperature sensor may be configured as an active component and connected to the evaluation unit via at least three conductor tracks.

[0021] In one embodiment of the device, the temperature sensor may be placed on the first printed circuit board side and the evaluation unit on the second printed circuit board side, so that the evaluation unit is on the side of the printed circuit board opposite to the temperature sensor. For example, the first printed circuit board side may contain substantially only the temperature sensor, and all other components may be placed on the second side opposite to the temperature sensor. Particularly advantageous is that the first printed circuit board side having a spring-mounted temperature sensor can be placed coplanar with the surface of the object being measured. The conductive track between the temperature sensor and the evaluation unit may have through-plating that penetrates the printed circuit board.

[0022] In an alternative embodiment, the temperature sensor and evaluation unit can be located on the same side of the printed circuit board. This allows for a thermal connection between the underside of the temperature sensor and the surface of the object being measured via the printed circuit board, and enables optimization of the printed circuit board with respect to thermal conductivity at the location of the temperature sensor.

[0023] The current-determining device comprises a shunt and a temperature-measuring device as described above. The shunt has two connection regions and a resistive region electrically positioned between the connection regions and having a substantially flat surface. The current-determining device is positioned in the resistive region of the shunt's surface such that the temperature sensor is thermally connected to the resistive region of the shunt. Here, voltage taps are positioned on both sides of the temperature sensor to electrically contact the surface of the shunt in order to detect the potential difference along the resistive region.

[0024] In one embodiment of the device, a printed circuit board is placed flat on the shunt so that the voltage taps electrically contact the surface of the shunt, and a temperature sensor is placed on the surface of the shunt. In this case, in the assembled state of the device, the temperature sensor is displaced by its entire height relative to the plane of the printed circuit board, thereby the remaining printed circuit board web provides a restoring force to the printed circuit board plateau, thereby applying contact pressure to the temperature sensor. In this embodiment, the temperature sensor is directly positioned in the resistive region and is optimally thermally connected to the resistive material by the spring action of the remaining printed circuit board web, resulting in high-precision temperature measurement, thus optimally satisfying the main requirements of a current-specification device. Furthermore, since the temperature sensor can be positioned in the center of the resistive region and in the center between the voltage taps, the temperature can be measured in the very region where the voltage drop due to the current flowing through the shunt is also measured. In this way, when specifying the current flowing through the shunt, temperature-related changes in the resistance of the material in the resistive region of the shunt can be optimally compensated for. At the same time, because the printed circuit board is placed almost flush with the surface of the resistive region, the conductor tracks within the printed circuit board that connect the voltage taps to the measurement circuit for measuring the voltage drop between the voltage taps are also placed very close to the surface of the resistive region, thus virtually avoiding conductor loops during voltage measurement.

[0025] In an alternative embodiment of the device, the temperature sensor and the evaluation unit are arranged on the side of the printed circuit board opposite the shunt. In this case, the printed circuit board plateau is mechanically connected to the surface of the shunt, and the printed circuit board plateau is displaceable with respect to the plane of the printed circuit board. In particular, the side of the printed circuit board plateau opposite the temperature sensor can be connected to the shunt, for example, by an adhesive. In this case, the offset between the plane of the printed circuit board and the surface of the shunt is compensated at the position of the printed circuit board plateau by displacing the printed circuit board plateau, and thus the temperature sensor, by only the offset with respect to the rest position in the plane of the printed circuit board. This embodiment optimally meets the requirements of the current determination device because the temperature sensor is optimally thermally connected to the resistive material by its lower surface, especially over the entire printed circuit board plateau, and the state is maintained even if the position of the printed circuit board with respect to the surface of the shunt changes.

[0026] The thermal connection of the lower surface of the temperature sensor can be further improved by the printed circuit board plateau having a heat conductor, such as a metal insert or a plurality of copper layers that are at least partially connected to each other. Starting from the state where the printed circuit board is arranged on the shunt so as to be as flush as possible with the above surface, due to the thermal and electromechanical effects acting on the shunt, especially at a high operating current, deformation of the shunt and / or the printed circuit board may occur, whereby the printed circuit board may be at least partially lifted from the shunt. In this case, since the printed circuit board plateau is mechanically fixed to the shunt to compensate for the offset between the plane of the printed circuit board and the surface of the shunt, it does not affect the thermal connection between the temperature sensor and the shunt.

[0027] Specifically, the voltage taps can be arranged symmetrically around the temperature sensor and can optionally be embodied as press-fit pins, spring contacts, solder connections, or screw connections to the shunt of the printed circuit board and / or the shunt.

[0028] In one embodiment, the shunt can be configured to pass a current with a current intensity greater than 100 amperes, preferably greater than 1000 amperes. In this case, the shunt can be integrally formed from one material, and the resistance region is substantially formed by a reduction in cross-section with respect to the cross-section of the connection region of the shunt. Thereby, material migration is avoided, and manufacturing costs and assembly costs are reduced.

[0029] Alternatively, the resistance region of the shunt can be made of a material different from the connection region, for example, a material having different electrical properties, and optionally, can include a reduction in the cross-section of the shunt. In this case, by knowing the electrical properties of the material of the resistance region more accurately than the electrical properties of the material of the connection region, particularly with respect to the temperature dependence of the resistivity of the material of the resistance region, a further improvement in current determination accuracy can be achieved. Here, it is not absolutely necessary to use a material with a particularly low temperature dependence of resistivity in the resistance region of the shunt. Rather, it is sufficient if the temperature dependence can be grasped and / or specified as accurately and reproducibly as possible.

[0030] In one embodiment, the reduction in the cross-section of the shunt in the resistance region can include a reduction in the cross-section to a value of 10 - 60% of the cross-section of the connection region of the shunt. Thereby, the current density becomes higher in the resistance region of the shunt than in the connection region, and as a result, the voltage drop for a given current flowing through the shunt becomes larger. This local increase in current density is accompanied by a temperature rise in the resistance region, but the effect is nullified by temperature compensation using a temperature measurement value representative of the resistance region and overcompensated by limiting it locally to a clearly defined measurement range.

[0031] To avoid unwanted electrical contact, an electrical insulation foil can be arranged between the temperature sensor and the surface of the shunt.

[0032] The power converter has energizing lines for carrying the DC and / or AC currents to be processed by the power converter. At least one of the energizing lines includes the current-finding device described above, which either bridges a portion of the energizing line or is incorporated into the energizing line. The power converter is configured to determine the current flowing through the energizing lines during the operation of the power converter from the potential difference along the resistance region of the shunt, detected by a voltage tap, and the resistance value of the resistance region, the resistance value used to calculate the current strength being a function of temperature, detected by a temperature sensor.

[0033] In a preferred embodiment, the power converter is configured for rated powers greater than 10 kW, preferably greater than 100 kW, and particularly preferably greater than 1000 kW. In those power classes, the identification of DC and / or AC currents handled by the power converter is particularly demanding due to their corresponding high amplitudes and can be performed with particular accuracy using the current identification devices described above, which can be particularly easily incorporated into the structure of the power converter. [Brief explanation of the drawing]

[0034] The present invention will be further described and explained below with reference to exemplary embodiments shown in the drawings. [Figure 1] Figure 1 shows a temperature measurement device. [Figure 2] Figure 2 shows a current identification device. [Figure 3] Figure 3 shows a cross-section of one embodiment of a current identification device. [Figure 4] Figure 4 shows a cross-section of a further embodiment of the current-specification device. [Modes for carrying out the invention]

[0035] Figure 1 shows a temperature measuring assembly 1 as one embodiment of a temperature measuring device according to the present invention. The temperature measuring assembly 1 comprises a printed circuit board 2. A temperature sensor 3 is disposed on the printed circuit board 2. A milled groove 4 extends around the temperature sensor 3 on the printed circuit board 2. The milled groove 4 can be formed on the printed circuit board 2 before component placement on the printed circuit board 2 or following the component placement process. The milled groove 4 extends substantially helically around the temperature sensor 3, leaving a printed circuit board web 5 adjacent to the milled groove 4 on both sides and similarly extending substantially helically.

[0036] The helical shape from which the milled groove 4 extends can be realized in various ways. Specifically, it can have a nearly straight section and a nearly right-angle turning section (see Figure 1), or it can be composed of arc segments with different radii. It is also conceivable to have a turning section that is not rectangular. For manufacturing reasons, it should be understood that a certain minimum radius is always unavoidable when milling the turning section. For this reason, the turning section usually includes an arc, and in the case of a 90-degree bend, it can specifically be a quarter circle. This means that the milled groove 4 can be manufactured inexpensively in one go, for example, using standard tools.

[0037] At the end of the remaining printed circuit board web 5, a printed circuit board plateau 2a is located, on which a temperature sensor 3 is positioned. The printed circuit board plateau 2a is completely surrounded by a milled groove 4. Furthermore, the remaining printed circuit board web 5 makes one full turn around the printed circuit board plateau 2a. The radius vector of the trajectory of the milled groove 4, in this case the vector from the center of the printed circuit board plateau 2a to the point of the milled groove 4, makes approximately two full turns around the temperature sensor 3, sweeping an angle of approximately 700 degrees from the beginning to the end of the milled groove 4, as shown in Figure 1, for example. In an alternative embodiment, the milled groove 4 may be even shorter, making only one and a half turns or one and a half turns, or one and a half turns, or one and a half turns, respectively, corresponding to an angle of approximately 500 degrees or 600 degrees, or respectively, around the temperature sensor 3.

[0038] The temperature measurement assembly 1 further comprises an evaluation unit 7. The evaluation unit 7 can be located on the same side of the printed 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 a conductor track 6. The conductor track 6 here extends along the rest of the printed circuit board web 5.

[0039] The temperature sensor 3 can be implemented as an active or passive component. An active temperature sensor 3 typically needs to be connected to the evaluation unit 7 via at least three lines, while a passive temperature sensor 3 needs to be connected to the evaluation unit 7 via two to four lines. For this purpose, the conductor track 6 contains an appropriate number of individual lines that run adjacent to each other or vertically on the rest of the printed circuit board web 5. When an active component is used as the temperature sensor 3, the evaluation unit 7 may also be located outside the printed circuit board 2, for example, in a separate assembly, so that the temperature sensor 3 is connected to an appropriate programmable logic or microcontroller via the conductor track 5 and further wiring.

[0040] Figure 2 shows a current-specification device having a current-specification assembly 10 and a shunt 11. In this example, the shunt 11 is integrally formed and includes a connection region 11a and a resistance region 11b. Here, the connection region 11a is, for example, part of a power converter and is configured to connect to a busbar carrying a high DC or AC current. For this purpose, the shunt 11 can bridge a disrupted portion of the busbar or form a busbar itself, for example, by making the input terminals or semiconductor circuit of the power converter connectable to one end of the shunt 11 and / or making the inductor or relay connectable to the other end of the shunt 11. Alternatively or additionally, the connection region 11a can be formed to connect to other types of current-carrying lines, such as cables, and the connection region can be provided with connection elements 14 for electrical and / or mechanical connection to adjacent components. In principle, the resistance region 11b can also be incorporated into a current-carrying line so that the connection region 11a simply defines an electrical contact point between the resistance region 11b and an adjacent component.

[0041] The current determination assembly 10 comprises a temperature measuring device as shown in Figure 1, having a printed circuit board 2, a temperature sensor 3, and a milled groove 4 extending around the temperature sensor 3. The temperature sensor 3 can be positioned 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 (see Figure 3). Alternatively, the temperature sensor 3 can be positioned on the side of the printed circuit board 2 opposite to the shunt 11, i.e., on the same side as the evaluation unit 7 (see Figure 4). Furthermore, the current determination assembly 10 has two voltage taps 12, which are positioned before and after the temperature sensor 3 along the direction of current I flow and are conductively connected to the surface of the resistance region 11b. A voltmeter 13 is connected to the voltage taps 12 to detect the voltage difference between potentials on the surface of the resistance region 11b at the location of the voltage taps 12.

[0042] An evaluation unit, which can be combined with or implemented separately from the evaluation unit 7, is not shown here, but it is possible to determine the amplitude of the current I flowing through the shunt 11 based on Ohm's law, using the measurement from the voltmeter 13 and the electrical resistance of the resistance region 11b. In this case, the electrical resistance of the resistance region 11b is generally temperature-dependent. Therefore, the electrical resistance used mathematically when determining the current strength is specified as a function of the temperature of the resistance region 11b, which is determined by the temperature sensor 3.

[0043] The resistive region 11b has a smaller cross-section than the connection region 11a. As a result, the current density of the current I flowing through the shunt 11 increases in the resistive region 11b. Since the shunt 11 is inherently optimized for the lowest possible losses, increasing the current density is advantageous in order to generate a voltage difference between the voltage taps 12 that is high enough to safely fall within the measurement range of the voltmeter 13. Alternatively, or in addition to the reduction in cross-section shown in Figure 2, the resistive region 11b can have a different material composition than the connection region 11a, for example, a material with (slightly) increased electrical resistance and / or a material with reduced temperature dependence of electrical resistance.

[0044] Figure 3 shows a cross-section of the current-determining device according to Figure 2 along the resistive region 11b. The printed circuit board 2 is placed flat on the surface of the shunt 11. The temperature sensor 3 is positioned 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 resistive region 11b, and rests on the surface of the resistive region 11b. As a result, relative to its resting position when the printed circuit board 2 is not mounted, the temperature sensor 3 is shifted by its total height 8a relative to the plane of the printed circuit board 2, in that the printed circuit board plateau 2a is offset by its total 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 connected to the rest of the printed circuit board 2 only by the remaining printed circuit board web 5. The offset of the printed circuit board plateau 2a by a height of 8a is distributed over the elastic deformation of the entire printed circuit board web 5, which has a suitable incline with respect to the plane of the printed circuit board 2.

[0045] The elastic deformation of the printed circuit board web 5 generates a restoring force that presses the temperature sensor 3 against the surface of the resistive region 11b. Simultaneously, the voltage tap 12 is pressed against the surface of the resistive region 11b by the printed circuit board 2 itself, resulting in electrical contact. Alternatively or additionally, the voltage tap 12 may also provide a mechanical connection between the printed circuit board 2 and the shunt 11, for example, by being formed as a press-fit contact that is pressed into corresponding holes on the surfaces of the printed circuit board 2 and the shunt 11. Other methods of making the voltage tap 12 electrically and / or mechanically contact the resistive region 11b are also possible, for example, by spring pins, screws or solder connections.

[0046] In particular, the offset of the printed circuit board plateau 2a made possible by the milled groove 4 allows the printed circuit board 2 to be placed coplanar with the surface of the resistance region 11b, even if the temperature sensor 3 is positioned between the printed circuit board 2 and the surface of the shunt 11. As a result, the electrical connections necessary to measure the voltage drop between the voltage taps 12, especially the line between the voltage taps 12 and the voltmeter 13, can extend in the immediate vicinity of the surface of the resistance region 11b, thereby minimizing undesirable conductor loops, especially those oriented perpendicular to the surface of the shunt 11.

[0047] Figure 4 shows a cross-section of a further embodiment of the current-determining device according to Figure 2 along the resistance region 11b. The temperature sensor 3 is located on the side of the printed circuit board 2 opposite to the shunt 11, i.e., on the same side as the evaluation unit 7. The printed circuit board plateau 2a on which the temperature sensor 3 is located rests on the surface of the resistance region 11b and is mechanically connected to the shunt 11 by, for example, an adhesive 9a. The adhesive can be embodied as a thermally conductive adhesive and optimized for high thermal conductivity. A thermal conductor 9b, for example, a copper inlay or a plurality of copper layers at least partially connected to each other, can be placed on the printed circuit board plateau 2a, thereby improving the thermal connection between the underside of the temperature sensor 3 and the shunt 11-side surface of the printed circuit board plateau 2a.

[0048] The printed circuit board 2 may have a specific offset 8b from the surface of the shunt 11. This offset may be intentionally selected for design reasons, for example. The plane offset of the printed circuit board 2 from the surface of the shunt 11 can also be minimized during manufacturing, particularly by placing the printed circuit board flat on the shunt 11. However, after assembly, an additional offset may occur if the shunt 11 and / or the printed circuit board 2 deform, particularly at the position of the printed circuit board plateau 2a. In particular, if the shunt 11 is mechanically fixed to the connection area 11a by the connection element 14, the action of mechanical forces during assembly or transport, or thermal expansion and / or electromagnetic forces occurring during operation, may cause inherently undesirable deformation of the shunt 11.

[0049] The mechanical connection of the printed circuit board plateau 2a to the shunt 11 causes the temperature sensor 3 to displace at the position of the printed circuit board plateau 2a by an amount equal to a specific offset between the printed circuit board 2 and the surface of the shunt 11, 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 connected to the rest of the printed circuit board 2 only by the remaining printed circuit board web 5. The offset of the printed circuit board 2 relative to the surface of the shunt 11 is distributed here over the elastic deformation of the entire printed circuit board web 5, which has a moderate inclination with respect to the plane of the printed circuit board 2. This offset generates a restoring force between the fixed printed circuit board level 2a and the printed circuit board 2, resulting in the printed circuit board 2 being pulled towards the shunt 11 by the printed circuit board web 5. Furthermore, the printed circuit board web 5 can compensate for the lateral offset of the printed circuit board 2 from its nominal mounting position.

[0050] In this case, the voltage tap 12 is electrically and mechanically connected to the resistance region 11b by means of, for example, press-fit contacts, spring pins, screws, plug-ins, or solder connections.

[0051] In this way, the milled groove 4 makes it possible to offset the printed circuit board 2, and at the same time, it is possible to ensure a thermal connection between the temperature sensor 3 and the resistance region 11b. As a result, a certain degree of deformation of the shunt 11 can be tolerated during operation. Alternatively or additionally, the requirements for 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 economical.

[0052] In the embodiment shown in Figure 4, the lower surface of the temperature sensor 3 is thermally connected to the resistance region 11b of the shunt 11 via the printed circuit board plateau 2a. In this case, since the temperature sensor 3 can be isolated from the surrounding air by the hood, the upper surface of the temperature sensor 3 is not affected by the airflow above the printed circuit board 2 and is mostly in thermal equilibrium with only the resistance region. This further improves the accuracy of temperature measurement in the resistance region. [Explanation of symbols]

[0053] 1. Temperature measurement assembly 2 Printed circuit boards 2a Printed circuit board plateau 3. Temperature sensor 4. Milled grooves 5 Printed Circuit Board Web 6 Conductor Tracks 7 Evaluation Units 8a Overall height 8b offset 9a Adhesive 9b Thermal conductor 10 Current Identification Assembly 11 Shunt 11a Connection area 11b Resistance area 12 Voltage Tap 13 Voltmeter 14 connection elements

Claims

1. A temperature measuring device comprising a printed circuit board (2), an evaluation unit (7) and a temperature sensor (3), a printed circuit board (2) having a milled groove (4) extending approximately spirally around the temperature sensor (3), the temperature sensor (3) being disposed on a printed circuit board plateau (2a) and displaceable parallel to a normal vector of the plane of the printed circuit board (2), and a restoring force being exerted between the printed circuit board (2) and the temperature sensor (3) when the temperature sensor (3) is displaced relative to the plane of the printed circuit board (2).

2. 10. The device of claim 1, A device characterized in that the temperature sensor (3) is spring-mounted by a printed circuit board web (5) remaining between the turns of the spiral milled groove (4).

3. 3. The device according to claim 1 or 2, A device characterized in that the temperature sensor (3) is displaceable by a spring stroke that includes at least its overall height (8a).

4. The device according to any one of claims 1 to 3, A device characterized in that said milled groove (4) extends along a continuous spiral shape.

5. The device according to any one of claims 1 to 4, A device characterized in that the milled groove (4) extends along a spiral shape including a plurality of substantially straight sections with substantially right-angle turns between them.

6. The device according to any one of claims 1 to 5, A device characterized in that the radius vector of the locus of the milled groove (4) sweeps over an angle of at least 600 degrees, preferably at least 700 degrees, so that the remaining printed circuit board web (5) makes at least three-quarters of a revolution around the temperature sensor (3), preferably at least one revolution.

7. The device according to any one of claims 1 to 6, 1. A device characterized in that the width of the printed circuit board web (5), the width of the milled groove (4) and the length of the milled groove (4) are set so that the restoring force between the printed circuit board (2) and the temperature sensor (3) is 0.1 to 10 Newtons, preferably 1 to 5 Newtons, when the temperature sensor (3) is displaced by its entire height (8a) parallel to the normal vector of the plane of the printed circuit board (2).

8. The device according to any one of claims 1 to 7, The device is characterized in that the thickness of the printed circuit board (2) is between 0.5 and 3 millimeters, the width of the milled groove (4) is between 0.3 and 3 millimeters, and the width of the remaining printed circuit board web (5) is between 0.3 and 3 millimeters.

9. The device according to any one of claims 1 to 8, A device characterized in that the outer edge of said milled groove (4) encompasses an area of ​​less than 200 square millimeters, preferably less than 100 square millimeters.

10. The device according to any one of claims 1 to 9, A device characterized in that electrical conductor tracks (6) for contacting said temperature sensor (3) with said evaluation unit (7) extend along the remaining printed circuit board web (5).

11. The device according to any one of claims 1 to 10, A device characterized in that the temperature sensor (3) is embodied as a passive component and is connected to the evaluation unit (7) via at least two conductor tracks (6).

12. The device according to any one of claims 1 to 10, A device characterized in that the temperature sensor (3) is embodied as an active component and is connected to the evaluation unit (7) via at least three conductor tracks (6).

13. The device according to any one of claims 1 to 12, 1. A device characterized in that the temperature sensor (3) is arranged on a first printed circuit board side and the evaluation unit (7) is arranged on a second printed circuit board side opposite the first printed circuit board side.

14. The device according to any one of claims 1 to 12, 10. A device characterized in that the temperature sensor (3) and the evaluation unit (7) are arranged on the same side of a printed circuit board.

15. A current determining device comprising a shunt (11) and a temperature measuring device according to any one of claims 1 to 14, the shunt includes a resistive region (11b) having a substantially flat surface; the current determining device is disposed on a resistive area (11b) on the surface of the shunt (11) such that the temperature sensor (3) is disposed in thermal connection with the resistive area (11b) of the shunt (11); A current determining device characterized in that voltage taps (12) are disposed on either side of the temperature sensor (3) and are in electrical contact with the surface of the shunt (11) to detect the potential difference along the resistive region (11b).

16. 16. The device of claim 15, The printed circuit board (2) is placed flat on the shunt (11) so that the voltage tap (12) is in electrical contact with the surface of the shunt (11), and the temperature sensor (3) is on the surface of the shunt (11); 1. A device characterized in that the temperature sensor (3) is displaced by its entire height (8a) relative to the plane of the printed circuit board (2), the remaining printed circuit board web (5) exerting a restoring force on the printed circuit board plateau (2a), thereby exerting a contact pressure on the temperature sensor (3).

17. 16. The device of claim 15, the temperature sensor (3) and the evaluation unit (7) are arranged on the side of the printed circuit board (2) opposite the shunt (11), and the printed circuit board plateau (2a) is mechanically connected to a surface of the shunt (11); The device is characterized in that the printed circuit board plateau (2a) is displaceable relative to the plane of the printed circuit board (2), and the position of the printed circuit board plateau (2a) compensates for the offset between the plane of the printed circuit board (2) and the surface of the shunt (3).

18. 18. The device of claim 17, A device characterized in that said printed circuit board plateau (2a) comprises a thermal conductor (9b) for making a thermal connection between said temperature sensor (3) and said resistive area (11b).

19. The device according to any one of claims 15 to 17, The device, characterized in that the voltage tap (12) is embodied as a press-fit pin on the printed circuit board (2), as a spring contact, as a solder connection, or as a screw connection to the shunt (11).

20. The device according to any one of claims 15 to 19, The device is characterized in that the shunt (11) is configured to pass a current having an amplitude greater than 100 amperes, preferably greater than 1000 amperes.

21. The device according to any one of claims 15 to 20, 1. A device characterized in that the shunt (11) has two connection regions (11a), the resistor region (11b) being arranged between the connection regions (11a) and being formed substantially by a cross-sectional reduction relative to the cross-section of the connection regions (11a) of the shunt (11).

22. The device according to any one of claims 15 to 20, 1. A device characterized in that the shunt (11) has two connection regions (11a), the resistive region (11b) being arranged between the connection regions (11a) and made of a different material than the connection regions (11a), and optionally comprising a cross-sectional reduction of the shunt (11).

23. The device according to any one of claims 15 to 22, A device characterized in that said cross-sectional reduction comprises a reduction in cross-section to a value between 10 and 60% of the cross-section of the connection region (11a) of said shunt (11).

24. 17. The device of claim 16, A device characterized in that an electrically insulating foil is arranged between the temperature sensor (3) and the surface of the shunt (11).

25. 19. The device according to claim 17 or 18, A device characterized in that the printed circuit board plateau (2a) is mechanically connected to the surface of the shunt (11) by an adhesive (9a).

26. 1. A power converter having current carrying lines for conducting direct current and / or alternating current processed by the power converter, at least one of the current carrying lines comprises a current determining device according to any one of claims 15 to 25, said device bridging an interruption in said current carrying line or being integrated in said current carrying line; The power converter is configured to determine a current flowing through the current-carrying line during operation of the power converter from a potential difference along a resistive area (11b) of the shunt (11) detected by the voltage tap (12) and a resistance value of the resistive area (11b), the resistance value being a function of a temperature detected by the temperature sensor (3).

27. 27. The power converter of claim 26, A power converter, characterized in that it is configured for a rated power greater than 10 kW, preferably greater than 100 kW, particularly preferably greater than 1000 kW.

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