Current measuring assembly, balancing system, balancing method and method for producing a current measuring assembly

Abstract

The invention relates to a current measuring assembly (1) having a current measuring resistor (2) with two connection parts (4,5) made of a conductor material and a resistor element (8) made of a resistor material between the connection parts. The current measuring assembly also has a printed circuit board (3) which is electrically and mechanically connected to the current measuring resistor (2) and has two voltage taps (12,13) for measuring the voltage drop across the current measuring resistor (2). According to the invention, one of the two voltage taps (12, 13) on the printed circuit board (3) has a plurality of separate conductor tracks (15) which are made of a conductor material and which branch off from the second contact surface (13) and are brought together at a junction point (16) such that the conductor tracks (15) form a parallel circuit. The invention further relates to a balancing system, to a balancing method, and to a method for producing such a current measuring assembly.

Description

[0001] DESCRIPTION

[0002] Current measuring arrangement, balancing system, balancing procedure and

[0003] Manufacturing method for a current measuring arrangement

[0004] Technical field of the invention

[0005] The invention relates firstly to a current measuring arrangement for measuring an electric current by means of a low-ohm current measuring resistor ("shunt"). Furthermore, the invention relates to a calibration system for calibrating the temperature coefficient (TK) of the resistance value of such a current measuring resistor. Furthermore, the invention also comprises a corresponding calibration method. Finally, the invention also relates to a manufacturing method for a current measuring arrangement according to the invention with a low-ohm current measuring resistor.

[0006] Background of the invention

[0007] It is known from the prior art (e.g., EP 0 605 800 A1) to measure an electric current using a low-resistance current measuring resistor according to the four-wire technique. The electric current to be measured is passed through the low-resistance current measuring resistor, and the voltage drop across the low-resistance current measuring resistor is measured and, according to Ohm's law, is a measure of the electric current.

[0008] It is also known from the prior art (e.g., DE 10 2009 031 408 A1) to arrange a circuit board on such a low-resistance current measuring resistor, wherein the circuit board is electrically and mechanically connected to the low-resistance current measuring resistor. In this case, measuring electronics (e.g., ASIC - Application-Specific Integrated Circuit) are arranged on the circuit board to measure the voltage drop across the low-resistance current measuring resistor. For this purpose, the circuit board has two voltage taps that engage the two terminals of the low-resistance current measuring resistor in order to measure the voltage drop across the resistance element of the low-resistance current measuring resistor.

[0009] The problem with the current measurement described above according to the four-wire technique using a low-ohm current measuring resistor is the fact that the temperature coefficient (TK) of the resistance value of the low-ohm current measuring resistor is subject to component variations, which leads to corresponding measurement errors.

[0010] US 2007 / 0 177 318 A1 discloses a corresponding current measuring arrangement comprising a current measuring resistor and a circuit board. The circuit board measures the voltage across the resistance element of the current measuring resistor via several spatially separated pairs of voltage taps, and the individual voltage taps each originate from a separate contact surface on the circuit board. Adapting the measuring geometry is achieved, at most, by adapting the evaluation of the various voltage measured values.

[0011] For the general technical background of the invention, reference should also be made to DE 10 2016 010 012 B4.

[0012] Description of the invention

[0013] The invention is therefore based on the object of solving the problem of component scattering of the temperature coefficient of the resistance value of the low-ohm current measuring resistor in current measurement according to the four-wire technique.

[0014] This object is achieved by a current measuring arrangement according to the invention, a corresponding adjustment system, an adjustment method or a manufacturing method according to the independent claims.

[0015] The current measuring arrangement according to the invention, in accordance with the known current measuring arrangement described above, firstly comprises a low-ohm current measuring resistor ("shunt"). The low-ohm current measuring resistor has two connection parts made of a conductor material (e.g., copper) for introducing the current to be measured into the current measuring resistor and for discharging the electrical current to be measured from the current measuring resistor. In addition, the current measuring resistor according to the invention has a resistance element made of a resistance material (e.g., Manganin®), wherein the resistance element is arranged between the two connection parts in the current flow direction, so that the electrical current to be measured flows through the resistance element during operation. Such a low-ohm current measuring resistor is known, for example, from EP 0 605 800 A1 and therefore needs no further description.Furthermore, the current measuring arrangement according to the invention, in accordance with the prior art described at the outset (e.g. DE 10 2009 031 408 A1), also comprises a printed circuit board that is electrically and mechanically connected to the current measuring resistor and can, for example, carry measuring electronics to measure the voltage drop across the low-ohm current measuring resistor. For this purpose, the printed circuit board has two voltage taps, each with a contact surface made of a conductor material (e.g. copper), for contacting the two connection parts of the low-ohm current measuring resistor. The two contact surfaces for contacting the low-ohm current measuring resistor are preferably arranged on the underside of the printed circuit board facing the current measuring resistor and are connected to the top side of the printed circuit board via vias.

[0016] The current measuring arrangement according to the invention is distinguished from the prior art in that at least one of the two voltage taps on the circuit board has several separate conductor tracks made of a conductor material that branch off from the respective contact surface and are joined at a junction point, so that the conductor tracks form a parallel circuit. The individual conductor tracks of these parallel circuits can each be individually separated, thereby changing the measurement geometry and the electrical resistance value of the parallel circuit. In the current measuring arrangement according to the invention, the individual conductor tracks of the parallel circuit between the respective contact surface and the junction point can each be individually separated to enable adaptation. This adaptation can serve various purposes, which are briefly described below.

[0017] In one variant of the invention, the separation of the individual conductor tracks of the parallel circuit serves to adjust or adjust the temperature coefficient of the resistance of the current measuring resistor, thereby solving the problem of disruptive component variations in the temperature coefficient of the resistance of the current measuring resistor. For this purpose, as many conductor tracks of the parallel circuit can be separated as necessary to adjust the temperature coefficient of the resistance of the current measuring resistor to the desired value. This is because separating the individual conductor tracks of the parallel circuit changes the measurement geometry and the resistance of the parallel circuit at the respective contact surface.

[0018] In another variant of the invention, however, the separation of the individual conductor tracks serves to adapt the circuit board, which is designed for various types of current measuring resistors and is designed as a universal circuit board, to the respective type of current measuring resistor. This also exploits the fact that separating the conductor tracks of the parallel circuit changes the measuring geometry and also the resistance value of the parallel circuit at the respective contact surface, which enables adaptation to the respective type of current measuring resistor.

[0019] In a preferred embodiment of the invention, the parallel conductor tracks run directly on the circuit board, preferably substantially parallel to the main current flow direction in the current measuring resistor and preferably also parallel to the longitudinal side edge of the current measuring resistor.

[0020] Furthermore, as already mentioned above, the contact surfaces for contacting the two connection parts of the current measuring resistor are preferably located on the underside of the circuit board facing the current measuring resistor, whereas the parallel and individually separable conductor tracks of the aforementioned parallel circuit are preferably located on the top side of the circuit board facing away from the current measuring resistor. This is advantageous because the parallel conductor tracks are thus freely accessible on the top side of the circuit board and can therefore be easily separated. The electrical connection between the respective contact surface on the underside of the circuit board and the parallel conductor tracks on the top side of the circuit board can be made by a through-hole in the circuit board, whereby such through-holes are known per se from the prior art and therefore need not be described in more detail.

[0021] Furthermore, in the preferred embodiment of the invention, there are preferably incisions ("current shadows") in the two connection parts in order to influence the current density in the current measuring resistor. Such incisions are also referred to as current shadows in the usual technical terminology and are known, for example, from DE 10 2021 103 241 A1.

[0022] The above-mentioned incisions ("current shadows") preferably originate from a longitudinal side edge of the current measuring resistor, preferably from the same longitudinal side edge of the current measuring resistor. It should also be noted that the two incisions transverse to the longitudinal side edge can optionally have the same depth or a different depth.

[0023] In a further development of the invention, the circuit board not only has two voltage taps for contacting the two terminals of the low-resistance current measuring resistor. Rather, the circuit board can have a total of four voltage taps for contacting the terminals of the current measuring resistor at four measuring points, which enables optimization of the voltage measurement at the low-resistance current measuring resistor. Thus, the four voltage taps can each be arranged in two pairs on the two terminals of the low-resistance current measuring resistor, so that the two voltage taps of a pair are located next to each other with respect to the main current flow direction.

[0024] Even with these additional voltage taps, it is possible that several separate conductor tracks are present, which form a parallel circuit and can each be separated individually to enable adaptation, as already described above.

[0025] In general, it should be noted that the conductor material of the connection parts of the low-ohm current measuring resistor or the contact surfaces of the circuit board preferably has a lower specific electrical resistance than the resistance material of the resistance element.

[0026] For example, the conductor material can be copper, a copper alloy, aluminum or an aluminum alloy.

[0027] Furthermore, it should be mentioned in general that the connecting parts and the resistance element as well as the complete current measuring resistor are preferably plate-shaped, as is also known from the prior art.

[0028] The current measuring resistor is preferably low-ohmic and preferably has a very small resistance value, which is preferably less than 1 Q, 500 mQ, 250 mQ, 100 mQ, 50 mQ, 20 mQ, 10 mQ, 5 mQ, 2 mQ, 1 mQ, 500 pQ, 250 pQ, 100 pQ or 50 pQ.

[0029] In addition, it should generally be mentioned that the conductor material has a specific electrical resistance that is preferably less than 10' 6 Om or 10' 7 Om.

[0030] The resistance material of the resistance element, on the other hand, preferably has a specific electrical resistance that is less than 10' 4 Om, 10' 5 Om or 10' 6 Om.

[0031] As already mentioned above, a resistance alloy can be used as the resistance material for the resistance element of the low-ohm current measuring resistor. For example, this can be a copper-manganese-nickel alloy, in particular CuMnl2Ni or CuMnNi 25-10. Alternatively, a copper-nickel alloy, in particular CuNi44, can be used. Furthermore, a nickel-chromium alloy, in particular NiCRbOAISi or NiCr3020, can also be used. However, the above-mentioned examples of resistance alloys are merely exemplary and do not limit the scope of protection.

[0032] Furthermore, it should be mentioned that the resistance element can be connected to the connecting parts by a welded joint, in particular by electron beam welding.

[0033] Furthermore, it should be noted that the circuit board may have an interface to output the measured voltage drop across the resistive element.

[0034] Regarding the parallel connection of separable conductor tracks mentioned above, it should be noted that the number of parallel-connected and individually separable conductor tracks can be greater than two, three, four, five, seven or ten in order to enable precise adjustment of the temperature coefficient (TC).

[0035] Furthermore, the circuit board can carry a measuring circuit which is connected to the voltage taps on the connection parts of the current measuring resistor in order to measure the voltage drop across the current measuring resistor.

[0036] As already mentioned above, separating the individual conductor tracks of the parallel circuit allows for the temperature coefficient of the resistance of the low-ohm current-sense resistor to be adjusted. To do this, preferably, enough of the parallel-connected conductor tracks are separated so that the temperature coefficient (TC) of the resistance of the current-sense resistor is less than ±500 ppm / K, 250 ppm / K, ±100 ppm / K, ±50 ppm / K, ±25 ppm / K, ±10 ppm / K, or ±5 ppm / K.

[0037] It should also be noted that the parallel-connected conductor tracks preferably all branch off from the second contact surface toward the first contact surface, while the parallel-connected conductor tracks starting from the second contact surface preferably all run essentially parallel to the long side edge of the current-sense resistor. It has already been mentioned above that separating the individual conductor tracks of the parallel circuit enables the current-sense resistor to be calibrated. For this purpose, the individual conductor tracks are preferably separated from the outside inward, so that in practice, only the outer conductor tracks of the parallel-connected conductor tracks are usually separated.

[0038] Furthermore, within the scope of the invention, it is possible for a trim cut to be introduced into the resistance element of the current measuring resistor in order to adjust the resistance value of the current measuring resistor.

[0039] In addition, a through hole can be arranged in the first connection part and / or in the second connection part for electrical and mechanical contacting, as is also known, for example, from EP 0 605 800.

[0040] Furthermore, it's generally worth mentioning that the conductor material for one of the two terminals can be copper or a copper alloy, while the conductor material for the other terminal is aluminum or an aluminum alloy. The terminals of the current measuring resistor can therefore be made of different conductor materials.

[0041] The current measuring arrangement according to the invention has been described above. However, the invention also comprises a calibration system for calibrating the temperature coefficient of the resistance value of the current measuring resistor in such a current measuring arrangement. For this purpose, the calibration system according to the invention has a current source for supplying an electric current to the current measuring resistor. Furthermore, the calibration system according to the invention has a temperature control device for controlling the current measuring resistor to a predetermined temperature. Furthermore, the calibration system according to the invention also has a voltage measuring device for measuring the voltage drop across the resistance element of the current measuring resistor. Furthermore, the calibration system according to the invention has a separating device for separating the parallel conductor tracks of the parallel circuit individually, which enables adjustment of the temperature coefficient.Furthermore, the balancing system according to the invention preferably also comprises an evaluation device for determining the number of conductor tracks to be separated in order to adjust the temperature coefficient of the resistance value of the current measuring resistor as a function of the measured voltage drops at different temperatures. The balancing system according to the invention thus sets various temperatures of the current measuring resistor and measures the respective voltage drops, which then enables the temperature coefficient to be calculated. Then, sufficient numbers of the parallel conductor tracks are separated in each case to adjust the temperature coefficient.

[0042] Furthermore, the invention also includes a calibration method for calibrating the temperature coefficient of the resistance value of the current measuring resistor of the current measuring arrangement according to the invention. The calibration method according to the invention comprises the following steps:

[0043] • Tempering the current measuring resistor to a specific temperature,

[0044] • Energizing the current measuring resistor with an electric current,

[0045] • Measuring the voltage drop across the resistance element of the current measuring resistor, and

[0046] • Disconnecting at least one of the conductor tracks of the second voltage tap depending on the electrical current, the measured voltage drop and the temperature.

[0047] In the preferred embodiment of the adjustment method according to the invention, the following steps are provided:

[0048] • Tempering the current measuring resistor to a predetermined first temperature, in particular to room temperature,

[0049] • Energizing the current measuring resistor at the first temperature with an electric current,

[0050] • Measuring a first voltage drop across the resistance element at the first temperature of the current measuring resistor,

[0051] • optionally calculating a first resistance value from the measured first voltage drop,

[0052] • Tempering the current measuring resistor to a specified second temperature,

[0053] • Energizing the current measuring resistor at the second temperature with an electric current,

[0054] • Measuring a second voltage drop across the resistance element at the second temperature of the current measuring resistor,

[0055] • Optionally, calculating a second resistance value from the measured second voltage drop. Furthermore, the calibration method according to the invention offers two alternative developments, which are briefly described below.

[0056] An alternative includes the following additional steps:

[0057] • Calculating a number of conductor tracks of the second voltage tap to be separated in order to adjust the temperature coefficient (TK) of the resistance value of the current measuring resistor as a function of the two temperatures and the measured voltage drops and the current, in particular such that the temperature coefficient (TK) of the resistance value of the current measuring resistor is less than +500 ppm / K, +250 ppm / K, +100 ppm / K, +50 ppm / K, +25 ppm / K, +10 ppm / K or 5 ppm / K, and

[0058] • Separating the calculated number of tracks of the second voltage tap.

[0059] Another alternative to the comparison method according to the invention, however, provides for the following additional steps in a further development:

[0060] • Calculate the temperature coefficient of the resistance value as a function of the two temperatures, the measured voltage drops and the current,

[0061] • Check whether the calculated temperature coefficient of the resistance value is within a specified acceptable range, and

[0062] • Disconnecting at least one of the conductor tracks if the calculated temperature coefficient is not within the specified acceptable range and repeating the above steps until the calculated temperature coefficient is within the specified acceptable range.

[0063] Furthermore, it should be mentioned in general that the separation of the parallel-connected conductor tracks in the current measuring arrangement according to the invention can be carried out, for example, by milling, scribing, drilling, reading or lithography, to name just a few examples.

[0064] Finally, the invention also claims protection for a novel manufacturing method for a current measuring arrangement that uses a universal printed circuit board suitable for many different types of current measuring resistors. Separating the individual conductor tracks of the parallel circuit allows the universal printed circuit board to be adapted to the respective type of current measuring resistor. The manufacturing method according to the invention preferably comprises the following steps:

[0065] • Providing a current measuring resistor, wherein the current measuring resistor belongs to one of several different types of current measuring resistors,

[0066] • Determination of the type of current measuring resistor,

[0067] • Providing a printed circuit board with a first voltage tap with a first contact surface made of a conductor material for voltage measurement at the current measuring resistor, in particular at the first connection part of the current measuring resistor, and a second voltage tap with a second contact surface made of a conductor material for voltage measurement at the current measuring resistor, in particular at the second connection part of the current measuring resistor, wherein the second voltage tap on the printed circuit board has a plurality of separate conductor tracks made of a conductor material that branch off from the second contact surface and are brought together at a junction point, so that the conductor tracks form a parallel circuit, wherein the printed circuit board is a universal printed circuit board that is suitable for the various types of current measuring resistors,

[0068] • Determining the number of parallel-connected conductor tracks of the printed circuit board to be separated in order to adapt the printed circuit board to the type of current measuring resistor, in particular by reading the number of parallel-connected conductor tracks to be separated from a database depending on the type of current measuring resistor, and

[0069] • Separating the determined number of parallel-connected conductor tracks on the circuit board to adapt the circuit board to the type of current measuring resistor.

[0070] The number of parallel conductor tracks to be separated can, for example, be read from a database depending on the type of current measuring resistor, whereby the number of conductor tracks to be separated is stored in the database for each of the different types of current measuring resistor.

[0071] Other advantageous developments of the invention are characterized in the subclaims or are explained in more detail below together with the description of the preferred embodiments of the invention with reference to the figures.

[0072] Brief description of the drawings

[0073] Figure 1A shows a schematic plan view of a current measuring arrangement according to the invention with a low-ohm current measuring resistor and a printed circuit board.

[0074] Figure 1B shows a detailed view of Figure 1A. Figure 1C shows the detailed view of Figure 1B, with some traces of the parallel circuit cut to adjust the temperature coefficient.

[0075] Figure 2 shows a diagram illustrating the temperature coefficient as a function of the number of separated conductor tracks of the parallel circuit at the measuring point.

[0076] Figure 3 shows a modification of the first embodiment according to Figures 1A-1C with four contact surfaces for voltage measurement at the low-ohm current measuring resistor.

[0077] Figure 4 shows a flow chart to illustrate the adjustment method according to the invention.

[0078] Figure 5 shows a highly simplified schematic representation of an adjustment system according to the invention.

[0079] Figure 6 shows a flow chart illustrating the adaptation of a universal printed circuit board to a specific type of current measuring resistor.

[0080] Figure 7 shows a modification of the flow chart according to Figure 4.

[0081] Figure 8A shows a perspective view of a modified current measuring arrangement.

[0082] Figure 8B shows a sectional view through the current measuring arrangement according to Figure 8A.

[0083] Figure 9 shows a modification of Figure 8B.

[0084] Figure 10 shows a further modification of the sectional view according to Figure 8B.

[0085] Detailed description of the drawings

[0086] In the following, the embodiment of a current measuring arrangement 1 according to the invention shown in Figures 1A-1C will now be described.

[0087] Thus, this embodiment initially comprises a low-ohm current measuring resistor 2 ("shunt") and a printed circuit board 3, wherein the printed circuit board 3 is electrically and mechanically connected to the current measuring resistor 2, as will be described in detail below.

[0088] The current measuring resistor 2 itself is largely conventionally constructed and essentially consists of two plate-shaped connecting parts 4, 5 made of a conductor material (e.g. copper) for introducing an electrical current I to be measured into the current measuring resistor 2 or for discharging the electrical current I to be measured from the current measuring resistor 2.

[0089] In the two connecting parts 4, 5 there are holes 6, 7 for electrical contacting of the two connecting parts 4, 5, as is known from the prior art.

[0090] In addition, the current measuring resistor 2 has a resistance element 8, which is arranged between the two connection parts 4, 5 and is thus passed through by the electrical current I to be measured during a measurement. The resistance element 8 is electrically and mechanically connected to the two adjacent connection parts 4, 5 via two weld seams 9, 10.

[0091] It should be noted that the resistance element 8 consists of a low-ohm resistance alloy (e.g. Manganin®), which, however, has a higher specific electrical resistance than the conductor material (e.g. copper) of the connecting parts 4, 5.

[0092] Furthermore, it should be mentioned that a trimming cut 11 is made laterally in the resistance element 8 in order to adjust the resistance value of the current measuring resistor 2, as is known per se from the prior art.

[0093] The circuit board 3 has two contact surfaces 12, 13 made of a conductor material (e.g., copper) on its underside facing the current measuring resistor 2. Contact surface 12 serves to measure the voltage at the connection part 4, while the other contact surface 13 serves to measure the voltage at the connection part 5. The two contact surfaces 12, 13 are connected by conductor tracks and vias to an interface 14 mounted on the top side of the circuit board 3.

[0094] In this respect, the current measuring arrangement 1 according to the invention corresponds to other current measuring arrangements, as are known per se from the prior art (e.g., DE 10 2009 031 408 A1). However, the invention is distinguished in that the contact surface 13 is connected via several parallel conductor tracks 15 to a junction point 16, which is then connected in a conventional manner to the interface 14. The parallel conductor tracks 15 form a parallel circuit and can each be individually separated in order to be able to adjust the temperature coefficient (TK) of the resistance value of the current measuring resistor 2. Figure 1B shows an initial state in which the conductor tracks 15 are all intact.Figure 1C, on the other hand, shows a calibrated state in which the outer conductor tracks 15 are separated, changing the measurement geometry and the resistance value of the parallel circuit at the contact surface 13, which influences the temperature coefficient TK, as can be seen in Figure 2. When calibrating the current measuring arrangement 1, as many of the conductor tracks 15 are separated as necessary to bring the temperature coefficient TK of the resistance value of the current measuring resistor 2 into an acceptable range. Figure 2 thus shows the curve of the temperature coefficient TK as a function of the number of separated conductor tracks 15.

[0095] Furthermore, the drawings also show two so-called current shadows 17, 18 in the connecting parts 4, 5. The two current shadows 17, 18 serve to influence the current density in the connecting parts 4, 5, as is known per se from the prior art.

[0096] Figure 3 shows a modification of the embodiment according to Figures 1A-1C, so that in order to avoid repetition, reference is made to the above description, the same reference numerals being used for corresponding details.

[0097] A special feature here is that, in addition to the contact surfaces 12, 13, two additional contact surfaces 19, 20 are provided, so that a total of four voltages U1a, Ulb, U2a, U2b can be measured at the connection parts 4, 5. The parallel connection of several parallel conductor tracks described above is provided at all four of these contact surfaces 12, 13, 19, 20, which enables adjustment of the temperature coefficient.

[0098] A further special feature of this embodiment is that not only the two current shadows 17, 18 are provided, but also two additional current shadows 21, 22 on the opposite side.

[0099] The flow chart shown in Figure 4 is now described below, which serves to clarify the adjustment method according to the invention.

[0100] In a first step S1, the current measuring resistor is first heated to a temperature T A =+20°C. In the next step S2, the current measuring resistor is then energized with a measuring current I=IMESS.

[0101] In the next step S3, it is then intended that the voltage drop U A across the current measuring resistor, ie at temperature T A =+20°C.

[0102] In the next step S4, it is then provided that the resistance value R A = U A / IMESS is calculated.

[0103] The steps S1-S4 are then repeated in the following steps S5-S8, but for a different temperature T B >+20°C.

[0104] In the next step S9, the number n of conductor tracks to be separated is calculated, which is required to adjust the temperature coefficient of the resistance value of the current measuring resistor.

[0105] In the next step S10, the previously calculated number n of conductor tracks is then separated.

[0106] Figure 5 shows a highly simplified schematic representation of a balancing system according to the invention with the current measuring arrangement 1 described above. In addition, the balancing system has a current source 23 in order to be able to supply current to the current measuring resistor 2 during a balancing process.

[0107] In addition, the adjustment system has a tempering device 24 to temper the current measuring resistor 2 during the adjustment process, as described above.

[0108] Furthermore, the adjustment system according to the invention has a voltage measuring device 25 in order to be able to measure the voltage across the current measuring resistor 2.

[0109] Furthermore, the adjustment system according to the invention has an evaluation unit 26 which calculates the number of parallel conductor tracks to be separated, which is necessary in order to adjust the temperature coefficient of the resistance value of the current measuring resistor 2.

[0110] A trimming device 27 then separates the required number of parallel conductor tracks on the top side of the circuit board 3. Figure 6 shows a flow chart illustrating the adaptation of a universal circuit board to a specific type of current measuring resistor.

[0111] In a first step S1, a universal circuit board is provided which is basically suitable for different types of current measuring resistors.

[0112] In the next step S2, a current measuring resistor of a specific type is then provided.

[0113] The next step S3 then involves mechanically and electrically connecting the universal circuit board to the current measuring resistor.

[0114] A step S4 then provides for the type of current measuring resistor to be determined.

[0115] In the next step (S5), the number of tracks to be cut is determined, which is necessary to adapt the universal circuit board to the respective type of current-sense resistor. For example, the number of parallel tracks to be cut can be read from a database depending on the type of current-sense resistor.

[0116] In the next step S6, the previously determined number of parallel conductor tracks on the top side of the universal circuit board is then separated in order to adapt the universal circuit board to the respective type of current measuring resistor.

[0117] Figure 7 shows a modification of the flow chart according to Figure 4, so that in order to avoid repetition, reference is again made to the above description.

[0118] A special feature of this embodiment is that the process is repeated iteratively until the temperature coefficient is within an acceptable range. If this is not the case, the outermost conductor track is separated in a step S11, which is repeated until the temperature coefficient is within the specified acceptable range.

[0119] The modified embodiment shown in Figures 8A and 8B will now be described. This modified embodiment largely corresponds to the previously described embodiments, so that, to avoid repetition, reference is made to the above description, with the same reference numerals being used for corresponding details.

[0120] A special feature of this embodiment is that the circuit board 3 has a notch 28 that runs across the resistance element 8, transverse to the current flow direction. This exposes the side edges of the circuit board 3 above the resistance element 8. The two contact surfaces 12, 13 each encompass the side edges of the circuit board 3 in the region of the notch 28 in a cap-like manner.

[0121] From Figure 8B it can also be seen that the notch 28 of the circuit board 3 has a width along the current flow direction that is smaller than the width of the resistance element 8 along the current flow direction.

[0122] Figure 9 shows a modification of the sectional view according to Figure 8B, wherein the width of the notch 28 in the circuit board 3 is substantially equal to the width of the resistance element 8 along the current flow direction.

[0123] Figure 10 shows a further modification of the sectional view according to Figure 8B, wherein the width of the notch 28 in the circuit board 3 is greater than the width of the resistance element 8 along the current flow direction.

[0124] The invention is not limited to the preferred embodiments described above. Rather, the invention allows for numerous modifications that also utilize the inventive concept and therefore fall within the scope of protection. In particular, the invention also claims protection for the subject matter and features of the subclaims, independent of the respective claims referred to. The invention thus encompasses various aspects of the invention that enjoy independent protection.

[0125] List of reference symbols:

[0126] 1 current measuring arrangement

[0127] 2 current measuring resistor,

[0128] 3 circuit board

[0129] 4 Connection part of the current measuring resistor for introducing the current to be measured

[0130] 5 Connection part of the current measuring resistor for conducting the current to be measured 6, 7 Holes in the connection parts for electrical contact

[0131] 8 resistance element

[0132] 9, 10 welds

[0133] 11 Trim cut in the resistance element

[0134] 12, 13 Contact surfaces on the underside of the circuit board for contacting the connection parts of the current measuring resistor

[0135] 14 Interface on the circuit board

[0136] 15 parallel conductor tracks

[0137] 16 Junction point of the parallel circuit

[0138] 17, 18 Current shadow in the connection parts of the low-ohm current measuring resistor

[0139] 19, 20 Contact surfaces on the underside of the circuit board for contacting the connection parts of the current measuring resistor

[0140] 21, 22 Current shadow

[0141] 23 Current source for energizing the current measuring resistor

[0142] 24 Temperature control device

[0143] 25 Voltage measuring device

[0144] 26 Evaluation unit

[0145] 27 Trim device

[0146] 28 Cut in the circuit board d Depth of the current shadow

[0147] I Current through the current measuring resistor

[0148] Ul voltage at the connection part for introducing the current into the current measuring resistor

[0149] U2 Voltage at the connection part for discharging the current from the current measuring resistor

[0150] Ula, Ulb Voltage at the connection parts for introducing the current into the current measuring resistor

[0151] U2a, U2b Voltage at the terminal for discharging the current from the current measuring resistor

Claims

CLAIMS 1. A current measuring arrangement (1) for measuring an electrical current (I), comprising a) a current measuring resistor (2) with a1) a first connection part (4) made of a conductor material, in particular for introducing the current (I) to be measured into the current measuring resistor (2), a2) a second connection part (5) made of a conductor material, in particular for conducting the electrical current (I) to be measured from the current measuring resistor (2), and a3) a resistance element (8) made of a resistance material, wherein the resistance element (8) is arranged in the current flow direction between the first connection part (4) and the second connection part (5) so that the electrical current (I) to be measured flows through the resistance element (8) during operation, and b) a printed circuit board (3) which is electrically and mechanically connected to the current measuring resistor (2), with b1) a first voltage tap (12) with a first contact surface (12) made of a conductor material for voltage measurement at the current measuring resistor (2),in particular on the first connection part (4) of the current measuring resistor (2), and b2) a second voltage tap (13) with a second contact surface (13) made of a conductor material for voltage measurement at the current measuring resistor (2), in particular on the second connection part (5) of the current measuring resistor (2), characterized in that c) the second voltage tap (13) on the circuit board (3) has a plurality of separate conductor tracks (15) made of a conductor material, which branch off from the second contact surface (13) and are brought together at a junction point (16), so that the conductor tracks (15) form a parallel circuit.

2. Current measuring arrangement (1) according to claim 1, characterized in that the parallel-connected conductor tracks (15) can be separated individually, in particular a) in order to adjust the temperature coefficient (TK) of the resistance value of the current measuring resistor (2) or b) in order to adapt the printed circuit board (3) provided for different types of current measuring resistors to the type of current measuring resistor (2).

3. Current measuring arrangement (1) according to one of the preceding claims, characterized in that a) the parallel-connected conductor tracks (15) run directly on the circuit board (3), and / or b) the parallel-connected conductor tracks (15) run essentially parallel to the main current flow direction in the current measuring resistor (2), and / or c) the parallel-connected conductor tracks (15) run essentially parallel to the long side edge of the current measuring resistor (2), and / or d) the second contact surface (13) is arranged on the underside of the circuit board (3) facing the current measuring resistor (2), while the parallel-connected conductor tracks (15) are arranged on the top side of the circuit board (3) facing away from the current measuring resistor (2), wherein the second contact surface (13) is connected to the parallel-connected conductor tracks (15) via a through-hole in the circuit board (3).

4. Current measuring arrangement (1) according to one of the preceding claims, characterized by a) a first notch (17) in the first connection part (4) of the current measuring resistor (2) for influencing the current density in the current measuring resistor (2), and / or b) a second notch (18) in the second connection part (5) of the current measuring resistor (2) for influencing the current density in the current measuring resistor (2).

5. Current measuring arrangement (1) according to claim 4, characterized in that a) the first notch (17) and the second notch (18) start from a longitudinal side edge of the current measuring resistor (2), in particular from the same longitudinal side edge of the current measuring resistor (2), and / or b) the first notch (17) and the second notch (18) have the same depth (d) or a different depth transversely to the longitudinal side edge.

6. Current measuring arrangement (1) according to one of the preceding claims, characterized by a) a third voltage tap (19) on the circuit board (3) with a third contact surface (19) made of a conductor material for voltage measurement at the current measuring resistor (2), in particular at the first connection part (4) of the current measuring resistor (2), and b) a fourth voltage tap (20) on the circuit board (3) with a fourth contact surface (20) made of a conductor material for voltage measurement at the current measuring resistor (2), in particular at the second connection part (5) of the current measuring resistor (2).

7. Current measuring arrangement (1) according to claim 6, characterized in that a) the first voltage tap (12) and the third voltage tap on the first connection part (4) are arranged next to one another with respect to the main current flow direction, and / or b) the second voltage tap (13) and the fourth voltage tap on the second connection part (5) are arranged next to one another with respect to the main current flow direction.

8. Current measuring arrangement (1) according to claim 7, characterized in that several or all of the voltage taps (12, 13, 19, 20) each have several separate conductor tracks (15) made of a conductor material, which branch off from the respective contact surface (12, 13, 19, 20) and are brought together at a respective junction point (16), so that the conductor tracks (15) form a parallel circuit.

9. Current measuring arrangement (1) according to one of the preceding claims, characterized in that a) the conductor material has a lower specific electrical resistance than the resistance material of the resistance element (8), and / or b) the conductor material is copper, a copper alloy, aluminum or an aluminum alloy, and / or c) the first connection part (4) and / or the second connection part (5) and / or the resistance element (8) is plate-shaped, in particular in the form of a flat or curved plate, and / or d) the current measuring resistor (2) has a resistance value that is less than 1 Ω, 500 mΩ, 250 mΩ, 100 mΩ, 50 mΩ, 20 mΩ, 10 mΩ, 5 mΩ, 2 mΩ, 1 mΩ, 500 Ω, 250 Ω, 100 Ω or 50 Ω, and / or e) the conductor material has a specific electrical resistance that is less 10' 6 Om or 10' 7Om, and / or f) that the resistance material of the resistance element (8) has a specific electrical resistance which is less than 10' 4 Om, 10' 5 Om or 10' 6 Om, and / or g) that the resistance material is a resistance alloy, in particular g1) a copper-manganese-nickel alloy, in particular CuMnl2Ni or CuMnNi 25-10, g2) a copper-nickel alloy, in particular CuNi44 or g3) a nickel-chromium alloy, in particular NiCRbOAISi, NiCr3020, and / or h) that the resistance element (8) is connected to the connection parts (4, 5) by a welded joint, in particular by electron beam welding, and / or i) that the circuit board (3) has an interface (14) to output the measured voltage drop across the resistance element (8), and / or j) that the number of parallel-connected and individually separable conductor tracks (15) is greater than two, three, four, five, seven or ten in order to enable a precise adjustment of the temperature coefficient (TK), and / or k) that the circuit board (3) carries a measuring circuit which, for measuring the voltage drop across the current measuring resistor (2), is connected on the one hand to the first voltage tap (12) and on the other hand to the junction point (16) of the second voltage tap, and / or l) that as many of the parallel-connected Conductor tracks (15) are separated,that the temperature coefficient (TK) of the resistance value of the current measuring resistor (2) is less than ±500 ppm / K, 250 ppm / K, ±100 ppm / K, ±50 ppm / K, ±25 ppm / K, ±10 ppm / K or ±5 ppm / K, and / or m) that the parallel-connected conductor tracks (15) all branch off from the second contact surface (13) in the direction of the first contact surface (12), and / or n) that the parallel-connected conductor tracks (15) all run essentially parallel to the longitudinal side edge of the current measuring resistor (2), starting from the second contact surface (13), and / or o) that only outer conductor tracks (15) of the parallel-connected conductor tracks (15) are separated, and / or p) that a trimming cut is made in the resistance element (8) of the current measuring resistor (2) (11) is inserted to adjust the resistance value of the current measuring resistor (2),and / or q) that a through hole (6, 7) is arranged in the first connection part (4) and / or in the second connection part (5) for electrical and mechanical contacting, and / or r) that the conductor material in one of the two connection parts (4, 5) is copper or a copper alloy, while the conductor material in the other connection part (4, 5) is aluminum or an aluminum alloy., 10. Current measuring arrangement (1) according to one of the preceding claims, characterized in that a) the printed circuit board (3) has a notch (28) which runs transversely to the current flow direction, and / or b) the first voltage tap (12) with the first contact surface (12) surrounds a side edge of the printed circuit board (3) in a cap-like manner, in particular on a side edge to the notch (28), and / or c) the second voltage tap (13) with the second contact surface (13) surrounds a side edge of the printed circuit board (3) in a cap-like manner, in particular on a side edge to the notch (28), and / or d) the notch (28) in the printed circuit board (3) has a width along the current flow direction which is d1) equal to the width of the resistance element along the current flow direction, d2) greater than the width of the resistance element along the current flow direction, or d3) smaller than the width of the resistance element along the current flow direction.

11. Adjustment system for adjusting the temperature coefficient (TK) of the resistance value of a current measuring resistor (2), comprising a) a current measuring arrangement (1) according to one of the preceding claims, b) a current source (23) for supplying the current measuring resistor (2) with an electric current (IMESS), c) a temperature control device (24) for controlling the temperature of the current measuring resistor (2) to a predetermined temperature (T A , T B ), and d) a voltage measuring device (25) for measuring the voltage drop (U A , U B ) across the resistance element (8) of the current measuring resistor (2) during the current supply by the current source (23) and at the temperature set by the temperature control device (24).

12. Adjustment system according to claim 11, characterized by a) a separating device (27) for separating at least one of the parallel-connected conductor tracks (15) of the second voltage tap (13), and / or b) an evaluation device (26) for determining the number of conductor tracks (15) to be separated in order to adjust the temperature coefficient (TK) of the resistance value of the current measuring resistor (2) as a function of the measured voltage drops (U A , U B ) at different temperatures (T A , T B ), in particular such that the temperature coefficient (TK) of the resistance value of the current measuring resistor (2) is less than ±500 ppm / K, ±250 ppm / K, ±100 ppm / K, ±50 ppm / K, ±25 ppm / K, ±10 ppm / K or ±5 ppm / K.

13. Adjustment method for adjusting the temperature coefficient (TK) of the resistance value of a current measuring resistor (2) of a current measuring arrangement (1) according to one of claims 1 to 10, comprising the following steps: a) tempering the current measuring resistor (2) to a specific temperature (T A , T B ), b) applying an electric current (IMESS) to the current measuring resistor (2), c) measuring the voltage drop (U A , U B ) across the resistance element (8) of the current measuring resistor (2), and d) separating at least one of the conductor tracks (15) of the second voltage tap (13) as a function of dl) the electrical current (IMESS), d2) the measured voltage drop (U A , U B ) and d3) the temperature (T A , T B ).

14. Adjustment method according to claim 13, characterized by the following steps: a) tempering the current measuring resistor (2) to a predetermined first temperature (T A), in particular to room temperature, b) energizing the current measuring resistor (2) at the first temperature (T A ) with an electric current (I ESS), c) measuring a first voltage drop (U A ) across the resistance element (8) at the first temperature (T A ) of the current measuring resistor (2), d) optionally calculating a first resistance value (R A ) from the measured first voltage drop (U A ), e) tempering the current measuring resistor (2) to a predetermined second temperature (T B ), f) energizing the current measuring resistor (2) at the second temperature (T B ) with an electric current (IMESS), g) measuring a second voltage drop (U B ) across the resistance element (8) at the second temperature (T B ) of the current measuring resistor (2), h) optionally calculating a second resistance value (R B ) from the measured second voltage drop (U B ).

15. Adjustment method according to claim 14, characterized by the following steps: a) Calculating a number of conductor tracks (15) of the second voltage tap (13) to be separated in order to adjust the temperature coefficient (TK) of the resistance value of the Current measuring resistor (2) depending on the two temperatures (T A , T B ) and the measured voltage drops (U A , U B ) and the current ( I MESS), in particular such that the temperature coefficient (TK) of the resistance value of the current measuring resistor (2) is less than ±500 ppm / K, ±250 ppm / K, ±100 ppm / K, ±50 ppm / K, ±25 ppm / K, ±10 ppm / K or 5 ppm / K, and b) separating the calculated number of conductor tracks (15) of the second voltage tap (13).

16. Adjustment method according to claim 14, characterized by the following steps: a) calculating the temperature coefficient (TK) of the resistance value as a function of a1) the two temperatures (T A , T B), a2) the measured voltage drops (U A , U B ) and a3) the current (I MESS), b) checking whether the calculated temperature coefficient (TK) of the resistance value lies within a predetermined acceptable range, and c) separating at least one of the conductor tracks (15) if the calculated temperature coefficient is not within the predetermined acceptable range and repeating the steps of claim 13 and the steps of claim 15 until the calculated temperature coefficient (TK) lies within the predetermined acceptable range.

17. Adjustment method according to one of claims 13 to 16, characterized in that the separation of the parallel-connected conductor tracks (15) of the second voltage tap (13) at the current measuring resistor (2) is carried out by one of the following methods: a) milling, b) scribing, c) drilling, d) lasering, e) lithography.

18. Adjustment method according to one of claims 13 to 17, characterized in that the conductor tracks (15) of the second voltage tap (13) at the current measuring resistor (2) are separated during adjustment, starting from the outside to the inside.

19. Manufacturing method for a current measuring arrangement (1), in particular for a current measuring arrangement (1) according to one of claims 1 to 10, comprising the following steps: a) providing a current measuring resistor (2), wherein the current measuring resistor (2) belongs to one of several different types of current measuring resistors, b) determining the type of the current measuring resistor (2), c) providing a printed circuit board (3) with c1) a first voltage tap (12) with a first contact surface (12) made of a conductor material for voltage measurement at the current measuring resistor (2), in particular at the first connection part (4) of the current measuring resistor (2), and c2) a second voltage tap with a second contact surface (13) made of a conductor material for voltage measurement at the current measuring resistor (2), in particular at the second connection part (5) of the current measuring resistor (2), c3) wherein the second voltage tap (13) on the printed circuit board (3) has several separate conductor tracks (15) made of a conductor material, which branch off from the second contact surface (13) and are brought together at a junction point (16),so that the conductor tracks (15) form a parallel circuit, c4) wherein the printed circuit board (3) is a universal printed circuit board (3) which is suitable for the various types of current measuring resistors, d) determining the number of parallel-connected conductor tracks (15) of the printed circuit board (3) to be separated in order to adapt the printed circuit board (3) to the type of current measuring resistor (2), in particular by reading the number of parallel-connected conductor tracks (15) to be separated from a database as a function of the type of current measuring resistor (2), and e) separating the determined number of parallel-connected conductor tracks (15) of the printed circuit board (3) to adapt the printed circuit board (3) to the type of current measuring resistor (2).

20. Manufacturing method according to claim 19, characterized in that the number of parallel-connected conductor tracks (15) to be separated is read out from a database as a function of the type of current measuring resistor (2), wherein the number of conductor tracks (15) of the universal printed circuit board (3) to be separated is stored in the database for the different types of current measuring resistors.

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