CURRENT-SENSING RESISTOR

Abstract

The invention relates to a current-sensing resistor for measuring an electric current (I), comprising two connection parts, a resistor element, a pair of voltage-sensing contacts for measuring a voltage drop across the resistor element, and at least one incision in at least one of the connection parts the incision surrounding one of the voltage-sensing contacts and preventing current flow across the incision. The invention provides for multiple pairs of voltage sensing contacts to be arranged in series in the direction of current flow.

Claims

1-15. (canceled)

16. A current-sensing resistor for measuring an electric current, having a) a first connection part made of a conductor material for introducing the electric current to be measured into the current-sensing resistor, b) a second connection part made of a conductor material for discharging the electric current to be measured from the current-sensing resistor, c) a resistor element made of a resistor material, the resistor element being arranged in the direction of current flow between the first connection part and the second connection part so that the current to be measured flows through the resistor element, d) at least one pair of voltage-sensing contacts for measuring a voltage drop across the resistor element, the voltage-sensing contacts each engaging one of the connection parts, and e) at least one incision in at least one of the connection parts, the incision surrounding one of the voltage-sensing contacts and preventing a current flow across the incision, f) wherein a plurality of pairs of voltage-sensing contacts are arranged one behind the other in the direction of current flow.

17. The current-sensing resistor according to claim 16, wherein the incision and the voltage-sensing contact surrounded by the incision are arranged centrally in the connection part with respect to the position transverse to the current flow direction.

18. The current-sensing resistor according to claim 16, wherein a) the current-sensing resistor has a certain center axis parallel to the current flow direction, b) the connection part with the incision has a certain width transverse to the current flow direction, and c) the voltage-sensing contact surrounded by the incision has an eccentricity relative to the center axis of the current-sensing resistor which is smaller than 50% of the width of the current-sensing resistor.

19. The current-sensing resistor according to claim 16, wherein a) the connection part with the incision has a certain width transverse to the current flow direction, and b) the incision in the connection part extends transversely to the current flow direction over at most 60% of the width of the connection part.

20. The current-sensing resistor according to claim 16, wherein a) the incision is arcuate, with a base transverse to the current flow direction and legs facing the resistor element parallel to the current flow direction, b) the legs of the incision have a width perpendicular to the current flow direction which is at least as large as the thickness of the resistor element, and c) the base of the incision has a width parallel to the current flow direction which is at least as large as the thickness of the resistor element.

21. The current-sensing resistor according to claim 20, wherein the legs of the incision project in the current flow direction into the resistor element and end in the resistor element.

22. The current-sensing resistor according to claim 20, wherein the legs of the incision end in the connection part in front of the resistor element in the current flow direction.

23. The current-sensing resistor according to claim 20, wherein the legs of the incision end in the direction of current flow at the boundary between the resistor element and the connection part.

24. The current-sensing resistor according to claim 16, wherein the incision in the connection part delimits a contact island, the contact island between the incision and the resistor element having an area of at least 4 mm.sup.2.

25. The current-sensing resistor according to claim 16, wherein a) at least one incision is arranged in each of the two connection parts, which incision surrounds a contact island for a voltage-sensing contact, and b) the incisions are arranged in pairs on opposite sides of the resistor element in the connection parts, namely in the same late-running position with respect to the central axis of the current-sensing resistor.

26. The current-sensing resistor according to claim 16, wherein in at least one of the two connection parts a plurality of incisions are arranged next to one another with respect to the direction of current flow, which incisions each surround a contact island for a voltage-sensing contact.

27. The current-sensing resistor according to claim 16, wherein a) the resistor element is divided into a first part and a second part, so that the current to be measured is divided into a first current path through the first part and a second current path through the second part of the resistor element, b) a cutout is provided in the resistor element which prevents current flowing across the cutout, so that the two current paths run on either side of the cutout, c) the cutout extends in the direction of current flow preferably over the entire length of the resistor element, and d) the cutout preferably extends in the direction of current flow into the connection parts.

28. The current-sensing resistor according to claim 27, wherein a) in the first current path in each case a plurality of voltage-sensing contacts are arranged one behind the other along the direction of current flow, b) in the second current path in each case a plurality of voltage-sensing contacts are arranged one behind the other along the current flow direction, and c) a pair of voltage-sensing contacts engages on the two parts of the resistor element in order to measure the voltage drop between the two parts of the resistor element transversely to the current flow direction.

29. The current-sensing resistor according to claim 27, wherein a) in the first current path in each case a plurality of voltage-sensing contacts are arranged side by side transversely to the direction of current flow, b) in the second current path in each case a plurality of voltage-sensing contacts are arranged side by side transversely with respect to the current flow direction, and c) in each case a plurality of voltage-sensing contacts are arranged on the two parts of the resistor element, namely transversely to the current flow direction next to one another.

30. The current-sensing resistor according to claim 16, wherein a) the conductor material is copper, a copper alloy, aluminum or an aluminum alloy, b) the conductor material of the connection parts has a smaller specific electrical resistance than the resistance material of the resistor element, c) the resistor element is electrically and mechanically connected to the two connection parts by a welded joint, d) the resistance material has a specific electrical resistance which is less than 2.Math.10.sup.-4 Ω.Math.m, e) the resistive material has an electrical resistivity greater than 2.Math.10.sup.-6 Ω.Math.m, f) the conductor material has a specific electrical resistance which is smaller than 10.sup.-6 Ω.Math.m, g) that the resistance is low resistance with a resistance value of at most than 1 .Math.Ω, h) the resistor element is plate-shaped, i) the connection parts are each plate-shaped, j) the current-sensing resistor has a length in the current flow direction which is less than 30 cm, k) the current-sensing resistor has a width at right angles to the current flow direction which is smaller than 20 cm, and l) the current-sensing resistor has a thickness which is smaller than 10 mm.

31. A current measuring device, comprising: a) the current-sensing resistor according to claim 16, b) a voltage measuring device for voltage measurement at the voltage-sensing contacts of the current-sensing resistor and for determining corresponding voltage measurement values, and c) an evaluation unit for determining the current flowing through the current-sensing resistor from the voltage measurement values.

32. The current measuring device according to claim 31, wherein the voltage-sensing contacts form a Wheatstone measuring bridge.

33. The current measuring device according to claim 32, wherein the voltage-sensing contacts form several redundant current measuring channels.

Description

[0041] Other advantageous further embodiments of the invention are indicated in the dependent claims or are explained in more detail below together with the description of the preferred embodiments of the invention with reference to the figures.

[0042] FIG. 1 shows a perspective view of a current-sensing resistor according to the invention.

[0043] FIG. 1B shows a top view of the current-sensing resistor according to FIG. 1A.

[0044] FIG. 1C shows an enlarged section of FIG. 1B with a voltage diagram.

[0045] FIG. 2 shows a variation of FIG. 1B with two incisions in the two connection parts.

[0046] FIG. 3 shows a variation of the embodiment according to FIGS. 1A-1C with a cutout in the current sensing resistor to divide the current flow into two parallel current paths.

[0047] FIG. 4 shows a modification of FIG. 3.

[0048] FIG. 5 shows a variation of FIG. 3.

[0049] FIG. 6 shows a further variation of FIG. 3.

[0050] Finally, FIG. 7 shows a current measuring device with a current-sensing resistor according to the invention.

[0051] In the following, a first embodiment of a current-sensing resistor 1 according to the invention will now be described, as shown in FIGS. 1A-1C. The current-sensing resistor 1 essentially consists of two connection parts 2, 3 made of a conductor material (e.g. copper) and a resistor element 4 made of a resistor material (e.g. Manganin®), the resistor element 4 being arranged in the direction of current flow between the two connection parts 2, 3, so that an electric current I to be measured is introduced into the current-sensing resistor 1 via the connection part 2, then flows through the resistor element 4 and is then discharged from the current-sensing resistor 1 again by the connection part 3. The electrical voltage dropping across the resistor element 4 is thus a measure of the electrical current I flowing through the current-sensing resistor 1 in accordance with Ohm’s law, which enables current measurement in accordance with the four-wire technique known per se.

[0052] For the introduction and discharge of the electric current, the two connection parts 2, 3 each have current connections 5 and 6 in the form of two bores, which are arranged on both sides of a central axis 7 of the current-sensing resistor 1. The bores of the current connections 5 and 6 respectively enable the screwing on of corresponding contacts, as is known per se from the prior art.

[0053] The voltage measurement at the current-sensing resistor 1 is carried out by numerous voltage-sensing contacts 8-19, which are arranged on the two connection parts 2, 3 in matrix form in rows transverse to the current flow direction and tracks along the current flow direction. The voltage-sensing contacts 8-19 are each formed as rectangular contact islands consisting of a separate conductive coating applied to the respective connection parts 2 and 3. The voltage-sensing contacts 8-19 can be connected together in any pairings within the scope of the voltage measurement and thus form several voltage measuring channels.

[0054] The voltage-sensing contact 14 is surrounded by a U-shaped incision 20. First, the U-shaped incision 20 has a base within the connection part 2. Furthermore, the U-shaped incision 20 has two legs which extend in the direction of current flow and reach into the resistor element 4, as can be seen in particular in FIG. 1C. The legs of the U-shaped incision 20 have a width b.sub.s perpendicular to the current flow direction, while the base of the U-shaped incision 20 has a width I.sub.s along the current flow direction. Furthermore, it can be seen from FIG. 1C that the resistor element 4 has a width I.sub.RM along the current flow direction. Finally, it is also apparent from FIG. 1C that the legs of the U-shaped incision 20 within the resistor element 4 have a leg length dl.

[0055] The following dimensioning rules should be observed for the above quantities:

[00001]$dl=0,1\text{-0},9\cdot I_{RM}$

[00002]$I_S\ge h$

[00003]$b_S\ge h$

[0056] The current-sensing resistor 1 has a length L=80 mm along the direction of current flow and a width B=40mm across the direction of current flow, while the thickness h=3 mm.

[0057] The potential diagram in FIG. 1C shows qualitatively the relationship of the voltage measurement values for different pairs of voltage-sensing contacts 8-19. The indices of the voltage values in the potential diagram correspond to the reference signs of the corresponding voltage-sensing contacts. The voltage value U1,2 thus designates the voltage between the voltage-sensing contacts 1 and 2.

[0058] FIG. 2 shows a modification of the embodiment example according to FIGS. 1A-1C, so that in order to avoid repetition, reference is first made to the above description, with the same reference signs being used for corresponding details.

[0059] A special feature of this embodiment example is that the current-sensing resistor 1 has two incisions 20.1, 20.2 arranged in the two connection parts 2 and 3, respectively, on opposite sides of the resistor element 4.

[0060] FIG. 3 shows a variation of the embodiments described above, so that to avoid repetition reference is again made to the above description, the same reference signs being used for corresponding details.

[0061] First of all, a special feature of this embodiment example is that the two incisions 20.1, 20.2 are not arranged on opposite sides of the resistor element 4, but on the same side of the resistor element 4, namely in the connection part 2.

[0062] A further special feature of this embodiment example is that the current-sensing resistor 1 has a incision 21 which extends along the center axis 7 of the current-sensing resistor 1 over the entire length of the resistor element 4 and extends into the adjacent connection parts 2 and 3, respectively. The incision 21 may, for example, consist of a protrusion and prevents current flow across the incision 21. The incision 21 thus divides the current I into two current paths on either side of the incision 21.

[0063] Furthermore, it should be mentioned that four additional voltage-sensing contacts 22-25 are provided in this embodiment example. The voltage-sensing contacts 8-25 are thus arranged in a matrix in four rows and four tracks.

[0064] FIG. 4 shows a variation of the embodiment example according to FIG. 3, so that in order to avoid repetition, reference is made to the above description, with the same reference signs being used for corresponding details.

[0065] It should be mentioned here that the incision 20.1 is arranged eccentrically with respect to the center axis 7 of the current-sensing resistor with a certain eccentricity e with respect to the center axis 7.

[0066] FIG. 5 again shows a further modification of the embodiment example according to FIG. 3, so that in order to avoid repetitions, reference is again made to the above description, the same reference signs being used for corresponding details.

[0067] A special feature of this embodiment example is that a total of four incisions 20.1-20.4 are arranged in the current-sensing resistor 1.

[0068] FIG. 6 shows a variation of the embodiment example according to FIG. 3, so that in order to avoid repetition, reference is made to the above description, with the same reference signs being used for corresponding details.

[0069] A special feature of this embodiment example is that there is only a single incision 20.

[0070] FIG. 7 shows a complete current measuring device with the current measuring stand 1 according to the invention and a voltage measuring device 26, which measures the voltage at the voltage-sensing contacts 8-19 in pairs and thus provides several measuring channels.

[0071] The measured voltage values are then forwarded to an evaluation unit 27, which calculates the electric current I from the measured voltage values, whereby the evaluation unit 27 can also weight the individual measured voltage values individually, whereby automatic calibration is also possible.

[0072] The invention is not limited to the preferred embodiments described above. Rather, the invention also enables a large number of variants and variations which also make use of the inventive concept and therefore fall within the scope of protection. In particular, the invention also claims protection for the subject-matter and the features of the dependent claims independently of the claims referred to in each case and, in particular, also without the technical teaching of the main claim. Thus, the invention comprises different aspects of the invention which enjoy protection independently of each other. For example, an independent aspect of the invention is the division of the current into two parallel current paths by means of the cutout running in the direction of current flow.

TABLE-US-00001 List of reference signs 1 Current sensing resistor 2, 3 Connection parts 4 Resistor element 5, 6 Current connections (holes in the connection parts) 7 Center axis of the current-sensing resistor 8-19 Voltage-sensing contacts 20, 20.1-20.4 Incision 21 Cutout in the current-sensing resistor 22-25 Voltage-sensing contacts 26 Voltage measuring device 27 Evaluation unit B Width of current-sensing resistor perpendicular to current flow direction b.sub.S Width of the legs of the incision perpendicular to the current flow direction d.sub.l Leg length of the legs of the incision within the resistor element e Eccentricity of the incision h Thickness of the current-sensing resistor I Current I.sub.RM Width of the resistor element along the current flow direction I.sub.S Width of the base of the incision along the current flow direction L Length of the current-sensing resistor along the current flow direction