CN116868063A - Current sensing resistor - Google Patents

Abstract

The invention relates to a current sense resistor (1) for measuring a current (I), comprising: two connections (2, 3) for introducing and discharging, respectively, a current (I) to be measured; a resistor element (6) made of a resistor material; a first voltage measurement contact (9) at the first connection (2) for measuring a voltage at the first connection (2); a second voltage measurement contact (11) at the second connection (3) for measuring a voltage at the second connection (3); and a cutout (13) in the second connection (3), the cutout (13) surrounding the second voltage measurement contact (11) and preventing a current from flowing through the cutout (13). In the invention, a third voltage measuring contact (12) is also provided at the second connection (3) for measuring the voltage at the second connection (3). The third voltage measurement contact (12) at the second connection (3) is arranged laterally offset with respect to the second voltage measurement contact (11) at the second connection (3) with respect to the main current flow direction.

Description

Current sensing resistor

Technical Field

The present invention relates to a current-sensing resistor (current-sensing resistor) for measuring current according to four-wire (four-wire) technology.

Background

It is known from patent document EP 0 605 A1 to measure the current by means of a low-resistance current sensing resistor ("shunt") according to the four-wire technique. The current to be measured flows through a low-resistance current sense resistor, whereby the voltage drop across the low-resistance current sense resistor is measured. The measured voltage drop across the low-resistance current sense resistor is then a measure of the current flowing through the low-resistance current sense resistor in accordance with ohm's law.

Further, a further developed low-resistance current sensing resistor is known from international application WO 2012/019784 A1, wherein the voltage measuring contacts of the low-resistance current sensing resistor are surrounded by cut-outs, which are also referred to as current shadows (current shadows) and are capable of preventing a current from flowing through the respective cut-outs. These cuts have a positive effect on the electric field distribution in the low-resistance current sense resistor. The disadvantage of this known current sense resistor according to the prior art is that: measurement errors cannot be easily detected.

With regard to the technical background of the invention, reference should also be made to patent documents DE 10 2020 111 634B3, DE 10 2013 005 939 A1, US2017/0089955 A1 and EP 3 671 225 A1.

Disclosure of Invention

The invention is therefore based on the task of creating a suitably improved low-resistance current sense resistor.

The above-mentioned task is solved by a current sensing resistor according to the invention as set forth in the independent claim.

The invention comprises the following general technical teachings: a three-point tap (three-point tap) for voltage measurement is provided on the low-resistance current sensing resistor, which allows three voltage measurements to be performed on a closed loop extending over the resistor element. Thus, the three-point tap provides three measurement channels that provide three voltage measurements. For error-free measurement, the sum of all voltages in the closed loop must be zero according to kirchhoff's second law. However, in the case of measurement errors, deviations from zero occur, which enable error detection.

First, as with the known current sensing resistor described at the outset, the current sensing resistor according to the invention has a first connection which is composed of a conductive conductor material (e.g. copper) and is preferably used for introducing the current to be measured into the current sensing resistor.

Furthermore, as in the case of the known current-sensing resistor described at the outset, the current-sensing resistor according to the invention has a second connection which is also composed of a conductive conductor material (for example copper) and is preferably used to draw the current to be measured out of the current-sensing resistor again.

In addition, the current sensing resistor according to the present invention also has a circuit formed of a resistor material (e.g.,) A resistor element is made which is arranged between the first connection portion and the second connection portion in the main current flow direction so that a current to be measured flows through the resistor element.

Furthermore, the current sensing resistor according to the present invention further comprises a first voltage measurement contact at the first connection and a second voltage measurement contact at the second connection for voltage measurement.

The second voltage measuring contact is surrounded by a cutout, which is also called a current shadow and which is able to prevent a current from flowing through the cutout. In contrast to the known current sensing resistor according to international application WO 2012/019784 A1, in the current sensing resistor according to the present invention, it is preferred that only one of the above-mentioned two connection parts is provided with a cut (current shadow) and the other connection part does not comprise such a cut.

The current sensing resistor according to the invention is characterized in that a third voltage measuring contact is additionally arranged on the second connection for measuring the voltage at the second connection. The third voltage measurement contact on the second connection is arranged laterally offset with respect to the second voltage measurement contact on the second connection with respect to the main current flow direction. Thus, three voltage measurement contacts enable the three-point tap and form a closed loop for voltage measurement, which allows the diagnostic function described above to be implemented. Thus, with four voltage measuring contacts, two such loops can be formed, each comprising three voltage measuring contacts, whereby the sum of the voltages on one loop circuit has to be zero.

In a preferred embodiment of the invention, the first voltage measuring contact on the first connection and the second voltage measuring contact on the second connection together form a first measuring channel for voltage measurement, on which first measuring channel a first voltage measurement value (U12) is output. Preferably, the first voltage measurement at the first measurement channel is performed parallel to the main current flow direction in the current sense resistor. In this embodiment, it is furthermore provided that the first voltage measuring contact on the first connection and the third voltage measuring contact on the second connection together form a second measuring channel for measuring a second voltage drop (U13) across the resistor element, which voltage drop is inclined relative to the main current flow direction. Furthermore, it is preferred that the second voltage measuring contact on the second connection and the third voltage measuring contact on the second connection together form a third measuring channel for measuring a third voltage drop (U23) transverse to the main current flow direction, in particular perpendicular to the main current flow direction. Thus, the three measurement channels provide three measurement voltage values (U12, U13, U23) which add up to zero taking into account error-free measurement of the sign. On the other hand, in the case where there is a deviation from zero, there is a measurement error.

In another embodiment of the invention, on the other hand, the second voltage measuring contact on the second connection and the third voltage measuring contact on the second connection together form a first measuring channel for measuring a first voltage drop (U23) transverse to the main current flow direction, in particular perpendicular to the main current flow direction. In this embodiment, it is preferred that the first voltage measuring contact on the first connection and the third voltage measuring contact on the second connection together form a second measuring channel for measuring a second voltage drop (U13) across the resistor element and inclined with respect to the main current flow direction. In addition, it is preferred that the first voltage measuring contact on the first connection and the second voltage measuring contact on the second connection together form a third measuring channel for measuring a third voltage drop (U12) across the resistor element, preferably parallel to the main current flow direction. In this embodiment, three-point tapping can also be implemented as well, and allows the above diagnostic function to be implemented.

In addition, a fourth voltage measuring contact, which is electrically conductively connected to the third voltage measuring contact for jointly measuring the voltage at the third voltage measuring contact and at the fourth voltage measuring contact, can be provided on the second connection within the scope of the invention. Thus, the third voltage measurement contact and the fourth voltage measurement contact provide a common voltage tap.

In addition, a fifth voltage measuring contact can be arranged on the first connection, which is electrically conductively connected to the first voltage measuring contact for jointly measuring the voltage at the first voltage measuring contact and at the fifth voltage measuring contact. Thus, the first voltage measurement contact and the fifth voltage measurement contact form one common voltage tap.

Furthermore, it should be mentioned that the first voltage measurement contact in the first connection is preferably arranged in the first connection in a centered manner with respect to both sides of the current sensing resistor, in particular with an eccentricity of less than 50%, 40%, 30%, 20%, 10% or even 5% of the width of the current sensing resistor.

The same preferably applies to the second voltage measuring contact and the cutout around the second voltage measuring contact in the second connection, which are also preferably arranged in the second connection in a centered manner with respect to the two sides of the current sensing resistor, in particular with an eccentricity of less than 50%, 40%, 30%, 20%, 10% or 5% of the width of the current sensing resistor.

On the other hand, the third voltage measurement contact in the second connection is preferably arranged in the second connection in an off-centered manner, so that the three-point tap forms a triangular loop on the resistor element.

Furthermore, it should be mentioned that the distance of the first voltage measurement contact at the first connection and the second voltage measurement contact at the second connection from both sides of the current sense resistor may preferably be substantially the same, such that the first voltage drop across the resistor element is measured parallel to the main current flow direction in the current sense resistor.

Furthermore, it should be mentioned that in the second connection, the third voltage measurement contact and the optional fourth voltage measurement contact may preferably be substantially the same distance from the central axis of the current sense resistor.

Furthermore, it should be mentioned that in the second connection, the second voltage measurement contact is preferably arranged between the third voltage measurement contact and the fourth voltage measurement contact (if any).

The aforementioned cut-outs (current shadows) in the second connection are preferably arc-shaped, in particular V-shaped or U-shaped. The base of the arc-shaped cutout is preferably arranged transversely to the main current flow direction in the current-sensing resistor, and the legs of the arc-shaped cutout are preferably arranged substantially parallel to the main current flow direction and face the resistor element.

Various possibilities exist with respect to the length of the leg of the incision, which will be briefly described below, within the scope of the present invention.

In a variant of the invention, the legs of the cut-out extend into the resistor element in the main current flow direction and terminate in the resistor element. In this case it is also possible that both legs protrude into the resistor element to the same extent or to different extents. The length of the legs in the resistor element may be in the range of 0.1mm to 3mm, 0.2mm to 2mm, 0.5mm to 1.5mm or may be about 1mm.

On the other hand, in another modification of the present invention, the leg portions of the slit terminate before reaching the resistor element in the main current flow direction, i.e., the leg portions of the slit do not protrude into the resistor element. In this case, the leg may be located at a distance from the resistor element, for example, the distance may be in the range of 0.1mm to 3mm, 0.2mm to 2mm, 0.5mm to 1.5mm, or may be 1mm.

On the other hand, in the third modification of the present invention, the leg portions of the cutout extend exactly to the boundary between the resistor element and the second connection portion.

Furthermore, it should be mentioned that the second voltage measuring contact and the cutout surrounding the second voltage measuring contact may alternatively be arranged in an off-center manner in the second connection. This means that the second voltage measurement contact and the cut-out around the second voltage measurement contact are at a smaller distance from one side of the current sense resistor than they are from the other opposite side of the current sense resistor. In this case, the cutout preferably starts from the nearer side of the current-sensing resistor and extends into the resistor element in an arc-shaped or L-shaped manner or at least to the boundary between the second connection and the resistor element.

In general, it should be noted that the present invention is not limited to a particular conductor material for each connection. For example, the conductor material may be copper, copper alloy, aluminum or aluminum alloy.

However, it should be mentioned that the conductor material of each connection generally has a resistivity that is smaller than the resistivity (specific electrical resistance) of the resistor material of the resistor element.

As such, the invention is not limited to a particular resistor material with respect to the resistor material of the resistor element. For example, copper alloys, such as copper-manganese alloys, etc., may be used. Examples of copper-manganese alloys include CuMn12Ni2 or CuMn7Sn2,3. In addition, copper-manganese-nickel alloys such as Cu84Ni4Mn12 or Cu65Mn25Ni10 may also be used. Furthermore, copper-chromium alloys may alternatively be used, or nickel alloys may alternatively be used.

In a preferred embodiment of the invention, the resistor element is electrically and mechanically connected to the two adjacent connections, for example by means of a welded connection, wherein an electron beam welded connection has proved to be particularly advantageous.

The resistor material of the resistor element preferably has a relatively small resistivity, which is preferably less than 2 x 10 ^-4 Ω·m、2×10 ^-5 Omega.m or 2X 10 ^-6 Omega.m. On the other hand, the resistivity of the resistor material is preferably greater than 2×10 ^-6 Omega.m or 2X 10 ^-7 Ω·m。

On the other hand, the conductor material of each connection preferably has an even lower resistivity, preferably less than 10 ^-6 Omega.m or 10 ^-7 Ω·m。

As already mentioned above, the current sense resistor in the present preferred embodiment has a low resistance. For example, the resistance value may be at most 1 μΩ, 10 μΩ, 20 μΩ, 33 μΩ, 50 μΩ, 100 μΩ, 500 μΩ, 10mΩ, 5mΩ, 2mΩ, or 1mΩ.

Furthermore, it should be mentioned that the current sensing resistor according to the invention may have a current carrying capability (current carrying capacity) allowing at least 1A, 10A, 100A, 1kA or even 5kA under continuous loading.

As regards the constructional design of the current sensing resistor, it should be mentioned that the resistor element and the respective connection portions are preferably each plate-shaped, wherein these plate-shaped elements may optionally be flat or curved.

The length of the current sensing resistor in the main current flow direction is preferably less than 30cm, 20cm, 10cm, 5cm, 2cm or 1cm, while the width of the current sensing resistor is preferably less than 20cm, 10cm, 5cm, 2cm or 1cm. On the other hand, the thickness of the current sensing resistor is preferably less than 10mm, 5mm, 4mm, 2mm or 1mm.

Furthermore, it should be mentioned that, as is known from patent document EP 0 605 A1, the two connection parts may each comprise a current connection for introducing current into or discharging current from a current sensing resistor, wherein these current connections may comprise holes capable of receiving screws, for example.

The voltage measurement contacts may each be formed as contact pads, which are composed of a conductive coating on the respective connection portions. For example, the contact pads may be substantially rectangular, wherein the coating material of the contact pads may be composed of a different conductor material than the underlying connection.

Furthermore, it should be mentioned that a trimming cut (trim cut) may be made in one or both sides of the resistor element for adjusting the resistance value of the current sensing resistor and/or the temperature coefficient of the resistance value of the current sensing resistor.

In a preferred embodiment of the invention, the current sense resistor has voltage measurement contacts for exactly three voltage measurement channels to enable the aforementioned three-point tap. The three-point tap enables voltage measurement along a closed loop over the resistor element, which allows for a diagnostic function.

The current sensing resistor according to the present invention has been described above as a single component. However, the invention also claims a current measuring device comprising such a current sensing resistor and a voltage measuring device for individually measuring the voltage at each measuring channel of the current sensing resistor.

The current measuring device may furthermore have an evaluation unit for determining the current flowing through the current sensing resistor from the respective voltage measurement values. Here, the evaluation unit can also realize a diagnostic function. For this purpose, the voltage measuring device may measure the voltages at the three measuring channels of the three-point tap and then calculate the voltage deviations that occur during the cyclic measurement along the closed loop. The evaluation unit may generate an error signal if the deviation exceeds a maximum allowable value.

Further advantageous embodiments of the invention are described in the dependent claims, and a more detailed explanation will be given below with reference to the accompanying drawings together with a description of preferred embodiments of the invention.

Drawings

Fig. 1A shows a perspective view of a current sense resistor of the present invention with three-point taps.

Fig. 1B shows a top view of the current sense resistor of fig. 1A.

Fig. 2A shows a top view of a current sense resistor of the present invention similar to the current sense resistor of fig. 1A and 1B.

Fig. 2B shows a modification of the current sensing resistor in fig. 2A, in which the legs of the cut-out terminate at the boundary of the resistor element.

Fig. 2C shows a modification of the current sensing resistor in fig. 2A, in which the leg of the slit does not extend to the resistor element.

Fig. 3 shows a series of resistance values as a function of leg length of the cut-out within the resistor element.

Fig. 4 shows an enlarged detail view of the current sense resistor of fig. 1A and 1B at the cut-out region.

Fig. 5 shows the resistance value variation as a function of temperature for different lengths of the slit inside and outside the resistor element.

Fig. 6 also shows the resistance value variation as a function of temperature for the case of different lengths of the slit inside and outside the resistor element.

Fig. 7 shows a current measuring device of the present invention comprising a current sensing resistor of the present invention.

Fig. 8 shows a top view of a variant embodiment of the current sense resistor of the present invention.

Fig. 9 shows a perspective view of a variant embodiment of the current sense resistor of the present invention.

Fig. 10 shows a flow chart for explaining the diagnostic process of the present invention.

Fig. 11A shows a modification of the embodiment of fig. 9, in which two additional cutouts are provided for influencing the temperature characteristic.

Fig. 11B shows a graph for explaining the temperature characteristic in the embodiment of fig. 11A.

Fig. 12 to 17 show various modifications of the embodiment of fig. 11A.

Detailed Description

Hereinafter, an embodiment of the current sense resistor 1 of the present invention as shown in fig. 1A and 1B will be described. Here, the current sense resistor 1 may be used for current measurement according to the four-wire technique as known from the prior art.

First, the current sensing resistor 1 comprises a first plate-like connection part 2 made of copper for introducing a current I into the current sensing resistor 1.

In addition, the current sensing resistor 1 further comprises a plate-like connection 3, which is also made of copper, and is used for leading out the current I from the current sensing resistor 1.

As is known from patent document EP 0 605 A1, in each of the two connection parts 2, 3, a hole 4 or 5 is provided in order to let a screw for a current connection pass through.

From the material of the resistor (e.g.,) The resistor element 6 is made between the two connections 2, 3. Here, the resistor element 6 is electrically connected at its two endsAnd is connected to the two connection portions 2 and 3 by beam welding.

As is known from the prior art, in the resistor element 6, trimming cuts 7, 8 are provided in its sides for adjusting the resistance value and the temperature coefficient of the current sensing resistor 1.

On the upper side of the current sensing resistor 1 four voltage measuring contacts 9, 10, 11, 12 are provided on the two connections 2, 3 for measuring the voltage drop across the resistor element 6 and also enabling a diagnostic function, which will be described in detail later.

The voltage measuring contact 11 in the second connection 3 is arranged centrally in the second connection 3 here and is surrounded by a cut-out 13, which cut-out 13 is also referred to as a current shadow and can prevent a current from flowing vertically through the cut-out 13. The cutout 13 is U-shaped with a base 14 and two legs 15, 16, the base 14 being perpendicular to the main current flow direction in the current sensing resistor 1, the two legs 15, 16 being parallel to the main current flow direction in the current sensing resistor 1 and facing the resistor element 6, where in the present embodiment the legs 15, 16 of the cutout 13 protrude into the resistor element 6 (see fig. 4).

The voltage measuring contact 9 forms, together with the voltage measuring contact 11, a first measuring channel 17, at which first measuring channel 17 a corresponding voltage measurement value U12 is output.

Furthermore, the voltage measuring contact 9 forms a second measuring channel 18 with the voltage measuring contact 12, at which second measuring channel 18 a further voltage measurement value U13 is output.

Finally, the voltage measuring contact 11 forms, together with the voltage measuring contact 12, a third measuring channel 19, at which third measuring channel 19 a further voltage measurement U23 is output.

The voltage measurement contacts 9, 11 and 12 form here a closed loop over the resistor element 6, so that the sum of all voltages in this loop must be zero according to kirchhoff's second law. Thus, as will be explained in detail later, the voltage taps 9, 11, 12 form three-point taps, which enable a diagnostic function to be achieved.

The optional voltage measurement contact 10 is conductively connected to the voltage measurement contact 12 such that the voltage measurement contacts 10, 12 form a common voltage tap.

The embodiment of fig. 2A corresponds to the above-described embodiment to a large extent, and therefore, with respect to the corresponding details, reference is made to the previous description to avoid repetition, and the same reference numerals are used. In this embodiment, the two legs 15, 16 of the U-shaped cutout 13 also protrude into the resistor element 6.

In the variant of fig. 2B, the legs 15, 16 of the U-shaped cutout 13 do not extend into the resistor element 6, but terminate at the boundary between the resistor element 6 and the connection 3.

In the variant of fig. 2C, the legs 15, 16 of the U-shaped cut 13 even end inside the connection 3, whereby the boundary between the resistor element 6 and the connection 3 is not reached.

Fig. 4 shows an enlarged view of the embodiment of fig. 1B in this region of the U-shaped cutout 13. Here it can be seen that the legs 15, 16 of the U-shaped cut-out 13 extend into the resistor element 6 by a length dx.

Fig. 3 shows the dependence of the resistance values on the kerf length dx for the local resistances R12, R13, R23 of the three-point taps (U12, U13, U23).

Further, fig. 5 shows the relative variation dR12 of the resistance value R12 as a function of temperature for different dx values.

Another such graph for R23 is also shown in fig. 6.

Fig. 7 no longer shows the current sensing resistor 1 of the invention as a separate component, but rather as a component of a current measuring device.

The voltage measuring channels 17, 18 and 19 are read out by a voltage measuring device 20, which voltage measuring device 20 records three voltage measured values U12, U13 and U23. Then, the voltage measuring device 20 transmits the measured voltage values U12, U13, U23 to the evaluation unit 21 having two functions.

On the one hand, the evaluation unit 21 calculates the current I flowing through the current sense resistor 1 from the measured voltage values U12, U13, U23 according to ohm's law.

On the other hand, the evaluation unit 21 also performs a diagnostic function for detecting a measurement error, which will be described later herein with reference to the flowchart in fig. 10. It has been mentioned above that the voltage measurements U12, U13, U23 represent voltages in a closed loop and that the sum of these voltages must be zero according to kirchhoff's second law.

Thus, the diagnostic method of the present invention provides in step S1 the following procedure: the current to be measured is caused to flow through the current sense resistor 1.

Then, in steps S2 to S4, voltage drops U12, U13, U23 are measured.

Then, in the next step S5, calculation of the deviation Δu=u12+u23-U13 is performed.

Then, in a next step S6, it is checked whether the deviation Δu exceeds a predetermined maximum value U _MAX 。

If this is the case, the current measurement is determined to be erroneous in step S8.

If this is not the case, the current measurement is deemed to be correct in step S7.

Fig. 8 shows a modification of the above embodiment. With regard to corresponding details, reference may be made to the previous description to avoid repetition and the same reference numerals are used.

A particular feature of this embodiment is that: further voltage measuring contacts 22, 23 are arranged in the connection 2 next to the voltage measuring contact 9, these voltage measuring contacts 22, 23 however forming a common voltage tap with the voltage measuring contact 9.

The embodiment of fig. 9 also corresponds in part to the above-described embodiments. With regard to corresponding details, reference may be made again to the previous description to avoid repetition and the same reference numerals are used.

A particular feature of this embodiment is that: the slit 13 is not U-shaped but L-shaped. The L-shaped cut 13 starts from one side of the current sensing resistor 1 and its other leg extends into the resistor element 6.

The embodiment of fig. 11A corresponds to a large extent to the embodiment of fig. 9. With regard to corresponding details, reference may be made to the previous description to avoid repetition and the same reference numerals are used.

A particular feature of this embodiment is that: a further cut 24 is arranged in the connection 3 at the side edge, which cut 24 can prevent a current from flowing through the cut 24.

The slit 24 starts from one side edge of the connection portion 3 and extends transversely to the main current flow direction in the current sense resistor 1.

The voltage measurement contact 12 is provided between the cutout 24 and the resistor element 6 and is located on a contact pad that is isolated from the cutout 24.

In addition, a slit 25 is provided in the connection portion 2, and the slit 25 can prevent a current from flowing through the slit 25.

In this case, the slit 25 starts from one opposite side edge of the connection part 2 and extends transversely to the main current flow direction in the current sense resistor 1. Thus, two slits 24, 25 are provided on opposite sides of the current sensing resistor 1, where the two slits 24, 25 have different lengths in this example, i.e. the slit 25 is longer than the slit 24.

The voltage measuring contact 9 is arranged between the cutout 25 and the resistor element 6 and is located on a contact pad isolated from the cutout 25.

As can be seen from the graph in fig. 11B, the notches 24, 25 improve the temperature characteristic of the current sense resistor 1. Here, each characteristic curve in fig. 11B shows the relative change of each of the voltage measurement values U12, U23, and U13 as a function of temperature. The voltage U12 is measured between the two voltage measuring contacts 9, 11, while the voltage U23 is measured between the two voltage measuring contacts 11, 12. Finally, the voltage U13 is measured between the voltage measuring contacts 9, 12. In this graph, the circular measurement points show the temperature dependence without the cuts 24, 25, while the triangular measurement points show the corresponding curves of the embodiment shown in fig. 11A with the cuts 24, 25. The comparison of the different characteristic curves clearly shows that: with the two incisions 24, 25 the temperature dependence of the measured voltage values is significantly reduced.

The embodiment of fig. 12 largely corresponds to the embodiment shown in fig. 11A described above. With regard to corresponding details, reference may be made to the previous description to avoid repetition and the same reference numerals are used.

A particular feature of this embodiment is that: the slit 13 is not L-shaped but circular.

Fig. 13 shows another modification of the embodiment of fig. 11A. With regard to corresponding details, reference may be made again to the previous description to avoid repetition and the same reference numerals are used.

A particular feature of this embodiment is that: the slit 13 is neither L-shaped nor circular, but extends straight and in a direction inclined with respect to the side of the current sensing resistor 1.

Fig. 14 shows a further variant of the embodiment which largely corresponds to the embodiment shown in fig. 11A described above, so that reference can be made again to the previous description to avoid repetition.

A particular feature of this embodiment is that: the two cutouts 24, 25 are circular. The two cutouts 24, 25 here start from opposite sides of the current sensing resistor 1 and then extend in an arc towards the resistor element 6, where the cutouts 24, 25 do not extend so far as to reach the resistor element 6.

Fig. 15 shows another modification of the embodiment of fig. 11A. For corresponding details, reference is again made to the description above for fig. 11A to avoid repetition, and the same reference numerals are used.

A particular feature of this embodiment is that: the two cutouts 24, 25 are L-shaped. These two slits 24, 25 start from opposite sides of the current sensing resistor 1 and then turn towards the resistor element 6, where the slits 24, 25 do not reach the resistor element 6.

Fig. 16 shows another modification of the embodiment of fig. 11A. With regard to corresponding details, reference may be made again to the previous description to avoid repetition and the same reference numerals are used.

A particular feature of this embodiment is that: a further voltage measuring contact 26 is additionally provided in the connection 2, which voltage measuring contact 26 is located adjacent to the resistor element 6 at a side of the connection 2.

In addition, the connection part 2 has a further cutout 27, which cutout 27 starts from the side of the connection part 2 and then extends in an L-shape into the resistor element 6, the cutout 27 in the connection part 2 isolating the contact pads for the voltage measuring contacts 26.

Thus, in this embodiment, the current sense resistor 1 has four voltage measurement contacts 9, 11, 12, 26, which enables a wide variety of voltage measurements.

The embodiment of fig. 17 corresponds to a large extent to the embodiment shown in fig. 16 described above. With regard to corresponding details, reference may be made to the previous description to avoid repetition and the same reference numerals are used.

The specific features of this embodiment are as follows: in the embodiment of fig. 17, the cut 27 extends further into the resistor element 6 than in the embodiment of fig. 16. The present invention is not limited to the above-described respective preferred embodiments. On the contrary, many variations and modifications are possible which utilize the concepts of the invention and are therefore within the scope of the invention. In particular, the invention also claims the subject matter and features of the dependent claims independent of the respective claims mentioned and in particular also without the features of the main claim. Accordingly, the present invention includes various aspects of the invention that enjoy protection independently of each other.

List of reference numerals:

1: current sensing resistor

2: connection for introducing a current into a current sense resistor

3: connection for extracting current from a current sense resistor

4: holes in connections for introducing current

5: holes in connections for drawing current

6: resistor element between connection portions

7. 8: trimming cut in resistor element

9 to 12: voltage measuring contact

13: u-shaped cut-outs in the connection

14: base of U-shaped incision

15. 16: leg of U-shaped notch

17 to 19: measuring channel of voltage measuring device

20: voltage measuring device

21: evaluation unit

22. 23: voltage measuring contact

24: cutouts in the connection

25: cutouts in the connection

26: voltage measuring contact

27: cutouts in the connection

I: current flowing through the current sense resistor

dx: leg length of U-shaped cut-out in resistor element

U12: voltage measurement

U13: voltage measurement

U23: voltage measurement

R12: resistance measurement

R13: resistance measurement

R23: resistance measurement

dR12: relative change in resistance measurements

dR13: relative change in resistance measurements

dR23: relative change in resistance measurements

Claims (23)

1. Current sense resistor (1) for measuring a current (I), comprising:

a) -a first connection (2) made of an electrically conductive conductor material, in particular for introducing a current (I) to be measured into the current sensing resistor (1);

b) -a second connection (3) made of an electrically conductive conductor material, in particular for draining the current (I) to be measured from the current sensing resistor (1);

c) A resistor element (6) made of a resistor material, the resistor element (6) being arranged between the first connection (2) and the second connection (3) in a main current flow direction such that the current (I) to be measured flows through the resistor element (6);

d) -a first voltage measurement contact (9) at the first connection (2) for measuring a voltage at the first connection (2);

e) -a second voltage measurement contact (11) at the second connection (3) for measuring a voltage at the second connection (3); and

f) A first cutout (13) in the second connection (3), the first cutout (13) surrounding the second voltage measurement contact (11) and preventing current from flowing through the first cutout (13),

the method is characterized in that:

g) A third voltage measuring contact (12) is arranged at the second connection (3) for measuring the voltage at the second connection (3) and

h) The third voltage measurement contact (12) at the second connection (3) is arranged laterally offset with respect to the second voltage measurement contact (11) at the second connection (3) with respect to the main current flow direction.

2. The current sense resistor (1) according to claim 1, characterized in that:

a) The first voltage measurement contact (9) at the first connection (2) forms together with the second voltage measurement contact (11) at the second connection (3) a first measurement channel (17) for measuring a first voltage drop (U12) across the resistor element (6) and preferably parallel to the main current flow direction, and

b) The first voltage measurement contact (9) at the first connection (2) forms together with the third voltage measurement contact (12) at the second connection (3) a second measurement channel (18) for measuring a second voltage drop (U13) across the resistor element (6) and inclined with respect to the main current flow direction.

3. The current sense resistor (1) according to claim 2, characterized in that:

the second voltage measurement contact (11) at the second connection (3) forms together with the third voltage measurement contact (12) at the second connection (3) a third measurement channel (19) for measuring a third voltage drop (U23) transverse to the main current flow direction, in particular perpendicular to the main current flow direction.

4. The current sense resistor (1) according to claim 1, characterized in that:

a) The second voltage measurement contact (11) at the second connection (3) forms together with the third voltage measurement contact (12) at the second connection (3) a first measurement channel for measuring a first voltage drop (U23) transverse to the main current flow direction, in particular perpendicular to the main current flow direction, and

b) The first voltage measurement contact (9) at the first connection (2) forms together with the third voltage measurement contact (12) at the second connection (3) a second measurement channel for measuring a second voltage drop (U13) across the resistor element (6) and inclined with respect to the main current flow direction.

5. The current sense resistor (1) of claim 4, characterized in that:

the first voltage measurement contact (9) at the first connection (2) forms together with the second voltage measurement contact (11) at the second connection (3) a third measurement channel for measuring a third voltage drop (U12) across the resistor element (6) and preferably parallel to the main current flow direction.

6. The current sense resistor (1) according to any of the preceding claims, characterized in that:

a) A fourth voltage measuring contact (10) is arranged at the second connection (3), the fourth voltage measuring contact (10) being connected to the third voltage measuring contact (12) in an electrically conductive manner for jointly measuring the voltages at the third voltage measuring contact (12) and at the fourth voltage measuring contact (10), and/or

b) A fifth voltage measuring contact (22, 23) is arranged at the first connection (2), the fifth voltage measuring contact (22, 23) being electrically conductively connected to the first voltage measuring contact (9) for jointly measuring the voltage at the first voltage measuring contact (9) and at the fifth voltage measuring contact (22, 23).

7. The current sense resistor (1) according to any of the preceding claims, characterized in that:

a) The first voltage measuring contact (9) is arranged in the first connection (2) in a centered manner with respect to both sides of the current sensing resistor (1), in particular with an eccentricity of less than 50%, 40%, 30%, 20%, 10% or 5% of the width of the current sensing resistor (1), and/or

b) The second voltage measuring contact (11) and the first cutout (13) surrounding the second voltage measuring contact are arranged in the second connection (3) in a centered manner with respect to both sides of the current sensing resistor (1), in particular with an eccentricity of less than 50%, 40%, 30%, 20%, 10% or 5% of the width of the current sensing resistor (1), and/or

c) The third voltage measuring contact (12) is arranged in an off-center manner in the second connection (3) and/or

d) The first voltage measurement contact (9) in the first connection (2) and the second voltage measurement contact (11) in the second connection (3) are substantially the same distance from both sides of the current sensing resistor (1) such that the first voltage drop (U12) across the resistor element (6) is measured parallel to the main current flow direction, and/or

e) In the second connection (3), the third voltage measurement contact (12) and the fourth voltage measurement contact are substantially the same distance from the central axis of the current sense resistor (1).

8. The current sense resistor (1) according to any of the preceding claims, characterized in that:

in the second connection (3), the second voltage measurement contact (11) is arranged between the third voltage measurement contact (12) and the fourth voltage measurement contact.

9. The current sense resistor (1) according to any of the preceding claims, characterized in that:

the first cutout (13) in the second connection (3) is arc-shaped, in particular U-shaped or V-shaped, and the first cutout (13) has a base and legs (15, 16), the base being transverse to the main current flow direction, the legs (15, 16) being substantially parallel to the main current flow direction and facing the resistor element (6).

10. The current sense resistor (1) according to claim 9, characterized in that:

a) The legs (15, 16) of the first cut protrude into the resistor element (6) in the main current flow direction and terminate in the resistor element (6), the legs (15, 16) of the first cut optionally protruding into the resistor element (6) to different extents or to the same extent, in particular with the following leg lengths (dx) within the resistor element (6):

a1 At most 3mm, 2mm, 1.5mm or 1mm, and/or

a2 At least 0.1mm, 0.2mm, 0.5mm or 1mm,

b) The legs (15, 16) of the first cutout terminate in the second connection (3) before reaching the resistor element (6) in the main current flow direction, in particular in the second connection (3) at a distance from the resistor element (6) of:

b1 At most 3mm, 2mm, 1.5mm or 1mm, and/or

b2 At least 0.1mm, 0.2mm, 0.5mm or 1mm,

c) The leg (15, 16) of the first cutout ends at a boundary between the resistor element (6) and the second connection (3) in the main current flow direction.

11. The current sense resistor (1) according to any of the preceding claims, characterized in that:

a) The second voltage measuring contact (11) and the first cutout (13) surrounding the second voltage measuring contact are arranged in an off-centered manner in the second connection (3) and/or

b) In the second connection (3), the first cut (13) starts from one side of the current sensing resistor (1) and extends into the resistor element (6) in an arc-shaped or L-shaped manner or at least to the boundary between the second connection (3) and the resistor element (6).

12. The current sense resistor (1) according to any of the preceding claims, characterized in that:

a) A second cutout (24) in the second connection (3) for influencing the temperature characteristic of the resistance value, the second cutout (24) in the second connection (3) preventing a current from flowing through the second cutout (24),

b) A third slit (25) in the first connection portion (2) for affecting a temperature characteristic of a resistance value, the third slit (25) in the first connection portion (2) preventing a current from flowing through the third slit (25), and

c) -an optional fourth cut (27) in the first connection (2) for generating a further voltage loop and/or for influencing the temperature characteristic of the resistance value, the fourth cut (27) in the first connection (2) preventing a current from flowing through the fourth cut (27).

13. The current sense resistor (1) of claim 12, characterized in that:

a) The second cutout (24) starts from a side edge of the second connecting portion (3) on the opposite side of the first cutout (13),

b) In the second connection (3), the third voltage measurement contact (12) is arranged on the same side edge of the second connection (3) as the second cutout (24),

c) In the second connection (3), the third voltage measurement contact (12) is arranged between the resistor element (6) and the second cutout (24),

d) The third cutout (25) starts from the side edge of the first connecting portion (2) on the same side as the first cutout (13),

e) In the first connection (2), the first voltage measurement contact (9) is arranged on the same side edge of the first connection (2) as the third cutout (25),

f) In the first connection (2), the first voltage measurement contact (9) is arranged between the resistor element (6) and the third cutout (25),

g) The optional fourth cutout (27) in the first connection (2) starts from the side edge of the first connection (2) opposite to the third cutout (25), and/or

h) A fourth voltage measurement contact (26) is optionally provided in the first connection (2), the fourth voltage measurement contact (26) being arranged between the fourth cutout (27) and the resistor element (6).

14. Current sense resistor (1) according to claim 12 or 13, characterized in that:

a) The second cutout (24) is L-shaped or arcuate, or extends straight and optionally transversely to the main current flow direction, and/or

b) The third cut (25) is L-shaped or arc-shaped, or extends straight and optionally transversely to the main current flow direction, and/or

c) The fourth cutout (27) is L-shaped or arc-shaped, or extends straight and transversely to the main current flow direction, and/or

d) The second cutout (24) in the second connection (3) extends up to the resistor element (6) or into the resistor element (6) or ends in the second connection (3) before reaching the resistor element (6), and/or

e) The third cutout (25) in the first connection (2) extends up to the resistor element (6) or into the resistor element (6) or ends in the first connection (2) before reaching the resistor element (6), and/or

f) The fourth cutout (27) in the first connection (2) extends up to the resistor element (6) or into the resistor element (6) or ends in the first connection (2) before reaching the resistor element (6).

15. The current sense resistor (1) according to any of claims 12 to 14, characterized in that:

a) The second incision (24) has a length substantially the same as the length of the third incision (25), or

b) The second incision (24) has a length different from the length of the third incision (25).

16. The current sense resistor (1) according to any of claims 12 to 15, characterized in that:

a) The first incision (13) has a length substantially the same as the length of the fourth incision (27), or

b) The first incision (13) has a length different from the length of the fourth incision (27).

17. The current sense resistor (1) according to any of the preceding claims, characterized in that:

a) The conductor material of the connection (2, 3) is copper, copper alloy, aluminum or aluminum alloy, and/or

b) The resistivity of the conductor material of the connection (2, 3) is smaller than the resistivity of the resistor material of the resistor element (6), and/or

c) The resistor material of the resistor element (6) is one of the following alloys:

c1 Copper alloys, in particular copper-manganese-tin alloys, in particular CuMn12Ni2 or CuMn7Sn2,3, or copper-manganese-nickel alloys, in particular Cu84Ni4Mn12 or Cu65Mn25Ni10, or copper-chromium alloys,

c2 Nickel alloys, in particular NiCr or CuNi, and/or

d) The resistor element (6) is electrically and mechanically connected to the two connections (2, 3), in particular by a welded connection, in particular by electron beam welding, and/or

e) The resistivity of the resistor material is less than 2 x 10 ^-4 Ω·m、2×10 ^-5 Omega.m or 2X 10 ^-6 Ω·m, and/or

f) The resistivity of the resistor material is greater than 2 x 10 ^-6 Omega.m or 2X 10 ^-7 Ω·m, and/or

g) The resistivity of the conductor material is less than 10 ^-6 Omega.m or 10 ^-7 Ω·m, and/or

h) The current sensing resistor (1) has a low resistance with a resistance value of at most 1 μΩ, 10 μΩ, 20 μΩ, 33 μΩ, 50 μΩ, 100 μΩ, 500 μΩ, 10mΩ, 5mΩ, 2mΩ or 1mΩ, and/or

i) The current sense resistor (1) has a current carrying capacity of at least 1A, 10A, 100A, 1kA or 5kA, and/or

j) The resistor element (6) is plate-shaped, in particular flat, and/or

k) The connecting parts (2, 3) are respectively plate-shaped, in particular flat, and/or

l) the length of the current sense resistor (1) in the main current flow direction is less than 30cm, 20cm or 10cm, and/or

m) the current sense resistor (1) has a width perpendicular to the main current flow direction of less than 20cm, 10cm or 5cm, and/or

n) the thickness of the current sensing resistor (1) is less than 10mm, 5mm, 4mm, 2mm or 1mm, and/or

o) the two connections (2, 3) each have at least one current connection (4, 5) for introducing and discharging the current (I), each current connection preferably having at least one hole (4, 5) in the respective connection, and/or

p) each of the voltage measuring contacts is a contact pad, which is formed by a conductive coating on the corresponding connection portion, and/or

q) each of said contact pads is substantially rectangular, and/or

r) the coating of the contact pad is composed of a different conductor material than the connection (2, 3), and/or

s) trimming cuts are made on one or both sides of the resistor element (6) for adjusting the resistance value of the current sensing resistor (1) and/or the temperature coefficient of the resistance value of the current sensing resistor (1),

t) the current sensing resistor (1) optionally has voltage measurement contacts for exactly two or exactly three measurement channels,

u) are optionally provided with three voltage measurement contacts (9, 11, 12), which three voltage measurement contacts (9, 11, 12) form a three-point tap on the closed loop at the first connection (2) on the one hand and at the second connection (3) on the other hand, which three-point tap provides three measurement channels (17 to 19), which three measurement channels (17 to 19) provide three voltage measurement values (U12, U13, U23) to enable fault diagnosis to be carried out.

18. A current measuring apparatus comprising:

a) The current sensing resistor (1) according to any of the preceding claims;

b) -voltage measuring means (20) for measuring the voltages in the first measuring channel (17) and in the second measuring channel (18) separately, and optionally additionally for measuring the voltages in the third measuring channel (19) separately; and

c) An evaluation unit (21),

c1 The evaluation unit (21) determines the current (I) flowing through the current-sensing resistor (1) from the voltage measurements (U12, U13, U23) in the respective measurement channel (17 to 19), and/or

c2 The evaluation unit (21) diagnoses measurement errors by evaluating the voltage measured values (U12, U13, U23) in the respective measurement channels (17 to 19).

19. The current measurement device of claim 18, wherein:

a) The voltage measuring device (20) measures the following voltages U12, U23 and U13,

u12 is: -a voltage between the first voltage measuring contact (9) at the first connection (2) and the second voltage measuring contact (11) at the second connection (3),

u23 is: -a voltage between the second voltage measurement contact (11) at the second connection (3) and the third voltage measurement contact (12) at the second connection (3),

u13 is: -a voltage between the first voltage measurement contact (9) at the first connection (2) and the third voltage measurement contact (12) at the second connection (3),

b) The evaluation unit (21) calculates the following deviations Δu from the voltages U12, U23, U13: Δu=u12+u23-U13, and

c) The evaluation unit generates an error signal if the deviation deltau exceeds a maximum allowable value.

20. Current measurement method, which measures a current by means of a current sense resistor (1) according to any of claims 1 to 17, and which comprises the steps of:

a) -flowing the current (I) to be measured through the current sense resistor (1);

b) During the current (I) to be measured flowing through the current sensing resistor (1), the following voltages U12, U23 and U13 at the current sensing resistor (1) are measured,

u12 is: -a voltage between the first voltage measuring contact (9) at the first connection (2) and the second voltage measuring contact (11) at the second connection (3),

u23 is: -a voltage between the second voltage measurement contact (11) at the second connection (3) and the third voltage measurement contact (12) at the second connection (3),

u13 is: -a voltage between the first voltage measurement contact (9) at the first connection (2) and the third voltage measurement contact (12) at the second connection (3); and

c) The current (I) is calculated from at least one of the measured voltages U12, U13, U23.

21. The current measurement method according to claim 20, wherein:

the fault diagnosis is performed by the following steps,

a) The deviation Δu is calculated from the voltages U12, U23, U13 according to the following formula:

Δu=u12+u23-U13; and

b) If the deviation DeltaU exceeds a maximum value, an error signal is generated.

22. Current measurement method, which measures a current by means of a current sense resistor (1) according to any of claims 1 to 17, and which comprises the steps of:

a) -flowing the current (I) to be measured through the current sense resistor (1);

b) During the current (I) to be measured flowing through the current sensing resistor (1), the following voltages U34, U41 and U31 at the current sensing resistor (1) are measured,

u34 is: -a voltage between the third voltage measurement contact (12) at the second connection (3) and the fourth voltage measurement contact (26) at the first connection (2),

u41 is: -a voltage between the fourth voltage measurement contact (26) at the first connection (2) and the first voltage measurement contact (9) at the first connection (2),

u31 is: -a voltage between the third voltage measurement contact (12) at the second connection (3) and the first voltage measurement contact (9) at the first connection (2); and

c) The current (I) is calculated from at least one of the measured voltages U34, U41, U31.

23. The current measurement method according to claim 22, wherein:

the fault diagnosis is performed by the following steps,

a) The deviation Δu is calculated from the voltages U34, U41, U31 according to the following formula:

Δu=u34+u41-U31; and

b) If the deviation DeltaU exceeds a maximum value, an error signal is generated.