Current measurement device and manufacturing method for the same

Abstract

To minimize an electric path length of a shunt.SOLUTION: A current measurement device includes a shunt resistor of a resistive core 1208 with an opening 1214 and measurement leads, a Rogowski coil 1206 with electrical contacts surrounding the resistive core 1208, conductive layers 1202, 1204, 1210 on first and second sides of the resistive core 1208, one or more insulative layers between the conductive layers and the Rogowski coil 1206, and the current measurement device is configured to combine signals from the shunt resistor and the Rogowski coil 1206. The current measurement device may have a Rogowski coil 1206 on a flexible substrate at least partially wrapped around the shunt resistor. The current measurement device has a rigid substrate and vias filled with a conductive material through the rigid substrate.SELECTED DRAWING: Figure 19

Description

[Technical field]

[0001] The present disclosure relates to current measuring devices, and more particularly to current measuring devices and methods for manufacturing current measuring devices. [Background technology]

[0002] High power switching devices are often built in modular form with screw terminals to connect to bus bars for high current termination. To support the rapid current changes during switching transients, capacitor banks, consisting of multiple large capacitors, are typically mounted on the bus bars and usually close to the module to minimize series inductance. This makes it difficult to insert a current measurement device between the capacitor bank and the module to measure the switching transients, because it would potentially insert so much inductance that it would change the transient being measured.

[0003] There are various approaches to address this problem, each with its own drawbacks. For example, one solution employs a Rogowski coil around the busbar. Rogowski coils have no DC capability, limited bandwidth, and can cause accuracy issues depending on the coil's position. Similarly, another solution uses a current transformer around an extension post between the busbar and the module. However, current transformers not only have no DC capability, they may add inductance, and typically have limited bandwidth.

[0004] Another approach is to insert coaxial shunts into the gaps of the busbars. Typically, these coaxial shunts have three concentric conductors in a cylindrical shape: an outer return path, a resistive shunt material in the middle, and a sense lead that runs through the innermost part of the coaxial shunt. Such coaxial shunts suppress the magnetic field between the outer and middle materials, cancelling the inductance that affects the sense lead, allowing DC coupling and wide measurement bandwidth. However, these shunts can be difficult to insert into the gaps of the busbars and can lengthen the electrical path and introduce unwanted inductance into the current path.

[0005] Large, rapidly changing currents, such as those commonly found in switching power supplies and motor drive circuits that use wide bandgap semiconductors (and also in lightning and other arcing flashes), are notoriously difficult to measure accurately.

[0006] One commonly used approach is to place a series resistor (or "shunt") in the current path and measure the voltage drop caused by the current and divide by the resistance. This approach handles DC and low frequencies well, but does not work well for frequencies below f c For frequencies above 100 Hz, the inductive voltage drop across the shunt exceeds the resistive voltage drop, causing adverse effects at high frequencies.

number

[0007] Inductive voltage drops can be eliminated by using a coaxial shunt, where the resistive element is a cylinder, the return current passes through a larger concentric outer cylinder, and the voltage measurement leads are routed out from the shunt inside the resistive cylinder. This symmetrical nature, and the outer return current path, ensures that the magnetic field generated by the current circulating between the shunt and the outer return path does not leave a magnetic field that would impart an inductive voltage drop to the measured voltage inside the shunt. Coaxial shunts eliminate the measurement inductance (the inductance involved in the measured voltage drop), but require a longer current path through the shunt, thus increasing the insertion inductance (the inductance inserted into the current path of the system under test). Even without the measurement inductance, coaxial shunts are bandwidth limited by the skin effect of the shunt material. As the frequency increases, the skin depth of the current in the conductor decreases. When the skin depth approaches the thickness of the resistive cylinder, a much lower component of the current flows inside the shunt, resulting in a smaller resistive voltage drop inside where the voltage is measured.

[0008] Another method to improve the usable bandwidth of a shunt is to add a cancelling mutual inductance M to the lead dress of the voltage measurement leads of a conventional shunt. c That is,

number

[0009] [Patent Document 1] JP 2004-257905 A [Patent Document 2] JP 2012-088318 A [Patent Document 3] JP 2022-054461 A [Patent Document 4] Japanese Patent Application Publication No. 7-43387 [Non-patent literature]

[0010] [Non-Patent Document 1] Materials referring to "Zirconia Materials", "Yttria Partially Stabilized Zirconia", CoorsTek Corporation, USA, [online], [Retrieved November 21, 2023], Internet<https: / / www.coorstek.com / media / 4256 / zirconia-materials.pdf> [Non-Patent Document 2] "What is a shunt resistor (current detection resistor)?", Electronics Trivia, ROHM Co., Ltd., [online], [Retrieved November 21, 2023], Internet<https: / / www.rohm.co.jp / electronics-basics / resistors / r_what14> [Non-Patent Document 3] "Four-terminal sensing" article, also known as Kelvin sensing, Wikipedia (English version), [online], [Retrieved November 21, 2023], Internet<https: / / en.wikipedia.org / wiki / Four-terminal_sensing> [Non-Patent Document 4] "TRCP Series Rogowski Current Probe" introduction site, Tektronix, [online], [searched November 21, 2023], Internet<https: / / www.tek.com / ja / datasheet / current-probes-0> Summary of the Invention [Problem to be solved by the invention]

[0011] Another current measurement technique is to sense the magnetic field along a closed loop that surrounds the measured current. A Rogowski coil senses the time derivative of this magnetic field, and the voltage induced in the Rogowski coil can then be integrated to determine the current flow. The Rogowski coil has the advantage of being inherently isolating and relatively easy to install, but it cannot measure DC currents. In fact, there is a trade-off between the low-frequency usable range of the Rogowski coil and its high-frequency bandwidth. Achieving low-frequency coverage would require a large mutual inductance between the coil and the current flow to maximize the coil voltage at low di / dt, while a high bandwidth would require a small self-inductance of the coil to minimize the time constant of the coil driving the integrator load impedance.

[0012] The disclosed technical configurations address shortcomings in the prior art. [Means for solving the problem]

[0013] Some embodiments of the present application include a test and measurement accessory device that includes a shunt configured to be inserted between a bus bar and a module. The accessory device can measure the voltage drop across the shunt so that a known resistance of the accessory device can be used to measure the current flowing between the bus bar and the module. Some embodiments of the shunt are configured as a washer with a sense lead passing through an interior portion or opening of the shunt. As described in more detail below, embodiments of the shunt minimize the length of the electrical path, and therefore the inductance inserted into the current path, while maintaining the DC performance and wide measurement bandwidth advantages of conventional shunt resistors. [Brief description of the drawings]

[0014] [Figure 1A] Figure 1A shows the screw terminals of the switching device module. [Figure 1B] Figure 1B shows another example of a switching device module screw terminal. [Diagram 2] FIG. 2 shows an example of a conventional coaxial shunt. [Diagram 3] FIG. 3 shows a cross-sectional view of the busbar and module connections with an embodiment of the shunt inserted. [Figure 4] FIG. 4 is a top view of the busbar and module connections of FIG. [Diagram 5] FIG. 5 shows a cross-sectional view of components of the shunt of FIG. [Figure 6] FIG. 6 shows a cross-sectional view of another embodiment of a shunt. [Figure 7] FIG. 7 illustrates an embodiment of a shunt. [Figure 8] FIG. 8 is a cross-sectional view of the shunt of FIG. [Figure 9] FIG. 9 shows a rotated cross-sectional view of the shunt of FIG. [Figure 10A] FIG. 10A shows a diagram of another embodiment of a shunt. [Figure 10B] FIG. 10B shows an exploded view of the shunt of FIG. 10A. [Figure 11] FIG. 11 shows a diagram of the components of an embodiment of the shunt. [Figure 12] FIG. 12 shows a diagram of the shunt of FIG. [Figure 13] FIG. 13 shows a block diagram of a current measurement accessory in a test and measurement system. [Figure 14A] FIG. 14A illustrates various embodiments of a current shunt. [Figure 14B] FIG. 14B illustrates various embodiments of the current shunt. [Figure 14C] FIG. 14C illustrates various embodiments of the current shunt. [Figure 14D] FIG. 14D illustrates various embodiments of the current shunt. [Figure 15A] Figure 15A shows an embodiment of a current shunt combined with a Rogowski coil. [Figure 15B] FIG. 15B is an enlarged view of the Rogowski coil of FIG. 15A. [Figure 16A] Figure 16A shows another embodiment of a current shunt combined with a Rogowski coil. [Figure 16B] FIG. 16B is an enlarged view of the Rogowski coil of FIG. 16A. [Figure 17] Figure 17 shows an embodiment of a current shunt combined with a Rogowski coil for installation on a busbar. [Figure 18] Figure 18 shows an embodiment of a current shunt combined with a Rogowski coil for surface mounting on a printed circuit board. [Figure 19] Figure 19 shows an exploded view of an embodiment of a washer-type current shunt combined with a Rogowski coil. [Figure 20] Figure 20 shows the resistor portion and contact plate of an embodiment of a washer-type current shunt combined with a Rogowski coil. [Figure 21] Figure 21 shows an embodiment of a Rogowski coil. [Figure 22] FIG. 22 shows an embodiment of the resistor portion of an embodiment of a washer-style current shunt. [Diagram 23] Figure 23 shows an embodiment of the assembled Rogowski coil and an embodiment of the measurement leads. [Figure 24] Figure 24 shows a single-ended embodiment of a Rogowski coil on a flexible substrate. [Diagram 25] Figure 25 shows a single-ended embodiment of a Rogowski coil on a flexible substrate. [Figure 26] Figure 26 shows an embodiment of a Rogowski coil on a flexible substrate that outputs a differential signal. [Figure 27] Figure 27 shows an embodiment of a Rogowski coil on a flexible substrate that outputs a differential signal. [Figure 28] Figure 28 shows an embodiment of a Rogowski coil on a flexible substrate that outputs a differential signal. [Figure 29] Figure 29 shows an embodiment of a Rogowski coil for a rigid substrate. [Diagram 30] FIG. 30 shows an embodiment in which a Rogowski coil is surface mounted on a rigid substrate. [Diagram 31] FIG. 31 shows an embodiment in which a Rogowski coil is surface mounted on a rigid substrate. [Diagram 32] FIG. 32 shows the current and field diagrams of an embodiment of a current monitor in a rigid substrate. [Diagram 33] Figure 33 shows the process flow for fabricating Rogowski coils on a rigid substrate. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] 1A and 1B show a module for a high power switching device. The module has screw terminals 100 that are used to connect the module to a bus bar (not shown in FIGS. 1A and 1B). The screw terminals 100 have bolts 110 to mechanically attach the bus bar to the screw terminals 100 and provide a current path between the module and the bus bar. To accommodate the rapid current changes during switching transients, a capacitor bank may be attached to the bus bar and may be mounted close to the module to minimize series inductance. However, this can make it difficult to insert a current measurement device between the capacitor bank and the module to measure the switching transient current, as this may introduce a large inductance that would change the transient current being measured.

[0016] FIG. 2 shows a cross section of an example of a conventional coaxial shunt 200 used to measure the voltage drop across the shunt. The shunt is comprised of multiple coaxial cylinders. The outer cylinder 202 is typically constructed of copper, while the inner cylinder 204 is formed of manganin. Pins 206 and 208 are current pins, and pins 210 and 212 are voltage pins. A center pin (sense lead) 212 is at the center of the coaxial shunt. A problem that arises with this type of structure is its current path. The current flows through the current pin 206 and along the outer cylinder 202 along a line indicated at 214. This relatively long current path increases the overall electrical path length of the circuit or device being measured. This can insert inductance into the path and alter the transient current being measured. As described below, embodiments of the present application minimize the added current path length.

[0017] FIG. 3 illustrates a test and measurement accessory having a shunt 300 that is inserted between a screw terminal 320 of an electronic module, such as the module illustrated in FIGS. 1A and 1B, and a bus bar 310. The screw terminal 320 may be an example of or similar to the screw terminal 100 illustrated in FIGS. 1A and 1B, but is shown enlarged in FIG. 3 to better illustrate the current path through the assembled components. The shunt 300 includes an opening 306, e.g., a hole that extends through the shunt. An embodiment of the shunt 300 is shaped to resemble a washer. Within its washer-like shape, the shunt 300 includes a resistive portion 302 and, in some embodiments, may also include an insulating portion 304.

[0018] In some embodiments, the resistive portion 302 surrounds the insulating portion 304, forming the outer and inner layers of the shunt 300. The shunt 300 may be between the screw terminal 320 and the bus bar 310, and provides a current path 330 between the bus bar 310 and the screw terminal 320 of the electronic module through the shunt 300. Specifically, the resistive portion 302 of the shunt 300 is configured to form part of the current path 330. The bolt 110 may then be inserted through the bus bar 310 and through the opening 306 in the shunt 300 and tightened into the threaded portion 322 of the screw terminal 320. This secures the shunt 300 between the bus bar 310 and the screw terminal 320, making good electrical contact between these components.

[0019] This bolt 110 may act as one contact 340 of the shunt, allowing detection of the voltage at the "bottom" end of the shunt 300 (the bottom end of the shunt 300 contacts the screw terminal 320). A second contact may be located on the bus bar 310 or connected directly to the bus bar 310 (e.g., at position 360) and detects the voltage at the "top" end of the shunt 300 (the top end of the shunt 300 contacts the bus bar 310). The resistive element 302 creates a voltage drop across the shunt 300 that can be measured at the first and second contacts. The measured voltage drop, along with the known resistance of the shunt, can be used to determine the current flowing through the shunt, and therefore the current flowing between the bus bar 310 and the screw terminal 320 of the module.

[0020] The bolt 110 extends through an opening 306 in the shunt 300 and conveniently functions as a sense lead, providing a contact 340 on the same "top" as the second contact 360 of the assembled accessory device. The contact 340 and bolt 110 are electrically isolated from the resistive portion 302 of the shunt 300 within the opening 306. In some embodiments, an insulating portion 304 of the shunt 300 electrically insulates the contact 340 from the resistive portion 302. In some embodiments, an air gap electrically insulates the contact 340 from the resistive portion 302. In some embodiments, there is both an insulating portion 304 and an air gap in the shunt.

[0021] FIG. 4 shows a top view of the assembly of FIG. 3 in which the busbar 310 is mechanically secured to the screw terminals 320 of the electronic module with the shunt 300 inserted between them. As mentioned above, embodiments of the disclosed technology utilize the bolt 110 as one sense lead for the shunt 300 and the busbar 310 as the other sense lead. These provide contact surfaces for making measurements, such as to which cables, test probe leads, or other measurement leads of a test and measurement device may be connected. These contacts allow the measurement of the voltage drop across the shunt, which is later converted into a measurement of current. Nevertheless, current crowding at the module can create a magnetic field that loops through the bolt 110, so that the measurement lead that contacts the contact surface can be affected by the magnetic flux generated by the current flowing through the busbar. As a result, the particular location of two or more contacts for the measurement leads on the contact surfaces of the bolt 110 and the busbar 310 may result in altered measurements due to the magnetic field looping through the bolt 110.

[0022] For example, as illustrated in FIG. 4, the measurement leads contacting the bolt 110 and busbar 310 at first locations 410, designated A' and B', and second locations 420, designated A" and B", may include several loop regions that are sensitive to magnetic flux. The locations labeled with the A variation are on the bolt, and the B variation is on the busbar 310. Because the polarity of the magnetic pickup varies between the measurement locations, a third measurement location 430, designated A and B, may serve as an intermediate location where magnetic pickup on the measurement leads is minimal. The specific location of this third measurement location 430 may depend on factors such as the thickness of the shunt 300 (shown in dashed lines since it is placed under the top of the bolt and on the busbar 310) and the particular current path within the screw terminals 320 of the electronic module's busbar 310.

[0023] In general, however, embodiments will have first and second contacts 340 and 360 of sufficient size to allow some intermediate position for placement of the measurement leads that reduces the effects of magnetic flux. The washer-like shape of shunt 300 maintains a relatively flat profile, thereby minimizing the added length of the current path due to shunt 300 compared to conventional shunt components. Minimizing the current path across shunt 300 in this manner reduces the added inductance inserted in the current path. Thus, by utilizing shunt 300 and careful placement of the measurement leads, two potential sources of measurement error in high power switching devices can be minimized.

[0024] Additionally, in the embodiment of the shunt 300 shown in FIG. 3, there may be an insulating shoulder washer 350. This insulating shoulder washer 350 may be present with the shunt 300 and may have a portion parallel to the bus bar 310 that is disposed between the bolt 110 and the bus bar 310. As shown in FIG. 5, the insulating shoulder washer 350 may also have conductive portions 356 and 358 that contact the bus bar 310 and the bolt 110 of FIG. 3. The conductive portions 356 and 358 may have pins 352 and 354, represented as A and B in FIG. 5. The pins 352 and 354 may provide connection locations for measuring the voltage between points A and B, including the voltage drop across the shunt 300 and the voltage drop due to contact resistance to the bus bar 310 on the upper side and the screw terminal 320 on the lower side of the shunt 300. Pins 352 and 354, together with conductive portions 356 and 358, busbar 310, and bolt 110, form at least two contacts for measuring the voltage drop across the assembly of components. Similar to the measurement location described in connection with FIG. 4, the user may rotate shoulder washer 350 to adjust the specific position of pins 352 and 354 to minimize magnetic flux pickup before fully tightening bolt 110 to screw terminal 320. In both the examples of FIG. 4 and FIG. 5, the optimal rotation position can be found experimentally by minimizing the high frequency content in the measured voltage. Since magnetic pickup (proportional to di / dt) is always orthogonal to the resistive voltage drop, regardless of polarity, the high frequency content can only be artificially increased. Thus, the minimum high frequency content corresponds to zero magnetic pickup, depending on the rotation.

[0025] FIG. 6 illustrates another example shunt 600. The shunt 600 includes a resistive portion 602 and an insulating portion 604 similar to the shunt 300, but includes a Kelvin sense configuration with a sense lead 610 present on the shunt 600 itself. The sense lead 610 resides on an interior portion of the shunt 600, e.g., passing through the insulating portion 604 and running parallel to the central axis of the shunt 600. In this manner, the shunt 600 may include its own sense lead 610 to avoid voltage drop across the contact resistance between the shunt 600 and the busbar and module shown in FIG. 3. Additionally, passing the sense lead 610 on an interior portion of the shunt 600 minimizes magnetic flux pickup.

[0026] All of the embodiments of the shunts herein have an opening through which one of the sense leads extends, similar to the conventional shunts described above, but the sense leads of the present invention are configured to be part of the current path, thereby adding minimal length to the current path, as opposed to the long current path of the conventional shunt shown in Figure 2.

[0027] FIG. 7 illustrates an embodiment of a shunt 700. In this embodiment, the shunt 700 may also include a resistive portion 702 and an insulating portion 704. The insulating portion 704 may be comprised of a ceramic washer, and the resistive portion 702 may be comprised of a resistive material on the surface of the ceramic washer, for example, painted on the inner surface of the ceramic washer as shown. An example of a material for the ceramic washer may be YTZP zirconia from CoorsTek, USA, although many other materials may be used in embodiments to provide a structural substrate for the resistive material. The embodiment may also include first and second conductive elements 720 and 722, with the first conductive element 720 disposed on the top surface and the second conductive element 722 disposed on the bottom surface of the ceramic washer forming the insulating portion 704. The conductive elements 720, 722 may be formed of, for example, gold or other metal, and may be electrically connected to the resistive portion 702, for example, by soldering or brazing. In addition, a first sense lead 710, which functions as a sense lead rather than a screw terminal bolt but is not shown in FIG. 7, provides one contact for the measurement lead and extends from the conductive element 722 on the bottom surface closest to the electronics module in FIGS. 1A and 1B to the top of the shunt 700 immediately adjacent the bus bar shown in FIG. 3. The conductive material forming this sense lead contact 710 may extend vertically parallel to the central axis of the shunt 700 but is insulated from the paint circuit forming the resistive portion 702. Thus, the first sense lead extends through an opening in the interior portion of the shunt 700. The sense lead 710 generally extends vertically through the thickness or height of the ceramic washer but is shown at an exaggerated height in FIG. 7.

[0028] The second sense lead 712 provides another contact and is formed by extending conductive material from the conductive element 720 on the top surface. The ceramic washer forming the insulator 704 may further include a first slot 714 and a second slot 716 for receiving the first sense lead 710 and the second sense lead 712, respectively. As shown, the conductive element 720 disposed on the top surface of the ceramic washer forming the insulator 704 may include a gap aligned with the slot 714, which prevents the sense lead 710 from contacting the upper conductive element 720. By rotating the shunt 700, a user can position the first sense lead 710 and the second sense lead 712 to minimize magnetic pickup from the magnetic field looping through the shunt 700.

[0029] The embodiment of FIG. 7 may further include at least one compressible conductive gasket 730. For example, the compressible conductive gasket 730 may be present on the top surface of the top conductive element 720 between the shunt 700 and the bus bar 310. An additional compressible conductive gasket 732 may be present on the bottom surface of the bottom conductive element 722 between the shunt 700 and the bottom of the screw terminal 320 of the electronic module. A compressible conductive gasket may be present in either or both of the above configurations and may protect the shunt 700 from compressive forces of mechanical attachment, such as the screw forces of the screw terminal. Finally, the embodiment of FIG. 7 may include at least one conductive locking washer 740. Although FIG. 7 shows a single washer 740 located on the top of the shunt 700, an embodiment may include a washer on either or both the top or bottom. A washer may replace one or more of the compressible conductive gaskets.

[0030] 8 illustrates a cross-sectional view of another embodiment of a shunt 700. As shown, embodiments of the shunt 700 may incorporate optional compressible conductive gaskets 730 and 732 on both the top and bottom surfaces of the shunt 700 to protect the insulation 704 from compressive forces. Additionally, in embodiments, the second sense lead 712 connected to the upper conductive element 720 may extend through a second slot 716 in the insulation 704 and exit the side of the shunt 700. The first sense lead 710 from the lower conductive element 722 is not visible in the cross-section illustrated in FIG. 8 because the first sense lead 710 extends through the insulation 704 and exits the side of the shunt 700 at a different circumferential location of the shunt 700 relative to the second sense lead 712. Stated another way, in the view shown in FIG. 8, the first sense lead 710 resides in a portion of the shunt 700 and emerges from a portion of the shunt 700 that is hidden and not shown in this cross-sectional view.

[0031] 9 shows a rotated cross-sectional view of the shunt 700. In this view, the first sense lead 710 exits to the side through an opening in the insulation 704 and is separated from the top conductive element 720 by a portion of the insulation 704.

[0032] FIG. 10A illustrates another embodiment of a shunt, shunt 900, and FIG. 10B illustrates an exploded view of the main elements of shunt 900. The shunt 900 includes a resistive portion 902 formed of multiple resistors 932 mounted on a flexible circuit 930, and an insulating portion 904. The resistive portion 902 may have an outer layer surrounding the insulating portion 904. According to this embodiment, conductive elements 920 and 922 may be disposed on both the top and bottom surfaces of the shunt 900. Each conductive element may contact the insulating portion 904 for mechanical support and may contact the resistive portion 902 using one or more clips. For example, clip 924 extends from conductive element 920 toward the opposing conductive element 922, and clip 926 extends from conductive element 922 toward conductive element 920. Each of the clips 924 or 926 has a structure that allows the conductive element (or lid) to contact the flexible circuit 930 and provide a conductive path across the shunt 900 via the resistor portion 902. Additionally, each of the conductive elements 920 or 922 may have a structure that shares a central axis with the shunt 900, allowing each of the clips 924 or 926 to rotate about the axis without losing contact with the flexible circuit 930.

[0033] A first sense lead contact 910 may be provided and extends from a bottom conductive element 922 through the inside of the opening of the shunt 900 and out a slot near the top of the shunt 900 (as shown in the bottom right image). In this embodiment, the sense lead may be fully integrated into the flex circuit. A second sense lead 912 may extend from the top conductive element 920 as shown in the top right image. By rotating the shunt 900, a user can position the first 910 and second 912 sense leads to minimize magnetic pickup by these measurement leads from the magnetic field looping through the shunt 900.

[0034] 11 and 12 show another embodiment 1000 of the shunt. FIG. 12 shows a ceramic insulator 1004 that provides a structural substrate for the shunt 1000, which has been removed in FIG. 11 to show the sense line lead and resistor. The conductive element 1020 is connected to the upper side of the resistor portion 1002 and has a sense lead 1012 as one of the contacts. The resistor portion 1002 in this embodiment may include multiple resistors and may have a circuit 1030. A hexagonal conductive element 1006 is electrically connected to the lower side of the resistor and has a second sense lead 1008 that extends through an opening inside the shunt 100 and exits on either side of the other sense lead 1012. FIG. 12 shows an assembly with an insulator 1004 that includes a ceramic washer on which the resistor 1002 and circuit 1030 reside. The resistors and circuit may be painted onto the exterior of the ceramic washer body 1004. By rotating the shunt 1000 , the user can position the sensing leads to minimize magnetic pickup from the magnetic field looping through the shunt 1000 .

[0035] Thus, embodiments provide a test measurement accessory for measuring the voltage of a current path between a busbar and a module that does not contribute significant inductance to the measurement. The accessory has a shunt with an opening through which one of the sense leads extends. The shunt allows the voltage drop across the shunt to be measured and converted to a current measurement while minimizing additional path length that may affect the measurement.

[0036] Embodiments of the disclosed technology generally include measuring a current using an apparatus including a combination shunt and Rogowski coil. The output of the combination shunt and Rogowski coil may be fed through a compensation pole, such as a passive RC or LR filter. Some embodiments may connect an output of the current measuring device to an isolation probe. This embodiment includes inserting a shunt having a sense lead into a current path to be measured. The current measuring device includes a Rogowski coil that wraps at least partially around the shunt. The current measuring device is configured to combine output signals from the shunt and the Rogowski coil. In some embodiments, the Rogowski coil is placed in series with the sense lead of the shunt.

[0037] This configuration reduces the voltage, i.e.

number

[0038] M c ≒L and M R >>LM c By doing so, the voltage can be approximated as follows:

number

[0039] Since DC and low frequencies are handled by the shunt action, the inductance of the Rogowski coil may be optimized for high frequency operation, allowing for designs with smaller coil inductance and a higher frequency range than a standalone Rogowski coil.

[0040] FIG. 13 shows a block diagram of a test and measurement system including a current measurement device in the form of a current shunt. Note that this diagram shows several components that are not necessary for the current measurement device, but provides a context for various embodiments of the current measurement device. In FIG. 13, a device under test (DUT) 1110 has a current measurement device 1112 attached to the DUT. The current measurement device may include built-in or "soldered" components, or removable components. The DUT is generally connected to a test and measurement instrument 1120 via one or more probes 1114. In some cases, one or more of the probes may comprise "isolation probes," where the probes are galvanically isolated from the test and measurement instrument. For high voltage and high frequency operation, including operation with wide band gap (WBG) devices, isolation probes allow for more accurate measurements and reduce the risk of electric shock.

[0041] As will be described in more detail below, one or more filters at the test and measurement instrument level may receive the output of the measurement device 1112. These are different from the compensation pole filters described above. The filters 1116 may take the form of separate components such as a digital signal processor or analog filters, or may result from the processor 1118 executing instructions to apply filtering to the input signal.

[0042] The Rogowski coil may be implemented in a two (or more) layer flexible circuit board, which may then be wrapped and soldered around a busbar or surface mounted metal alloy shunt 1130 as shown in Figures 14A-14D. The coil may be wrapped around a resistive section 1132 or 1136 of the shunt 1130, which may typically be made of manganin. In the embodiment of Figure 14A, a sensing lead such as 1134 protrudes from the shunt bar. Figures 14B-14D show different embodiments of the resistive section 1132 or 1136 in the center of a copper section.

[0043] 15A and 16A show various embodiments of a current measurement device combining a shunt with a sense lead and a Rogowski coil. FIGS. 15B and 16B show close-up views of the Rogowski coils 1141 and 1151 of FIGS. 15A and 16A, respectively. In the single-ended implementation shown in FIG. 15A, a reference potential (which may consist of the shield or isolation barrier of an isolation probe) may be connected to one side of the shunt 1140. A Rogowski coil 1141 may be connected to the other side of the shunt, R f One end of the coil may be connected to this Rogowski coil, and R f The other end of C f and may be connected to the input of the probe, C f The other end may be connected to the reference potential of the probe.

[0044] One set of traces, designated 1142, is formed on one layer of the flex circuit closest to the shunt. The other set of traces, designated 1144, is formed on the opposite layer of the flex circuit, away from the shunt. In some embodiments, the flexible circuit may have an insulating layer or flexible dielectric core between the layer with traces 1142 and the layer with traces 1144, and in some embodiments may further have insulating layers as the top and bottom layers of the flexible circuit. Traces 1142 are connected to traces 1144 through vias 1143 in the flex circuit, such that the traces and vias form a continuous conductive Rogowski coil structure within the flex circuit. This allows the magnetic field that loops around the shunt to flow between the two sets of traces as the coil wraps around the shunt. M c A section of the trace labeled 1146 is placed on the opposite side of the return current path, as close as possible to the shunt, to form a canceling mutual inductance. A section of the Rogowski coil then wraps around at least a portion of the shunt's circumference. In one embodiment, a transmission line (such as 1148) is connected to the coil. In another embodiment, the transmission line may be connected to an isolation barrier, and in yet another embodiment, the isolation barrier is in the probe head. The output of the coil may be connected to a fixed time constant unipolar compensation circuit 1146. FIG. 15A shows an embodiment of a unipolar compensation circuit, with a filter resistor R f and the filter capacitor C f The present invention includes an RC filter having a

[0045] FIG. 16A illustrates an embodiment for differential signaling. In a differential implementation, a shield portion of an isolation barrier, such as the shield of an isolation probe, may be connected to either side of the shunt. One half of a Rogowski coil 1151 (i.e., one half of a first set of traces 1152 and one half of a second set of traces 1154) may be placed on either side of the shunt to provide a differential signal through a compensation pole circuit 1156. This differential signal is then fed to the Cf R on both sides leading to f Alternatively, C f Two capacitors, 2·C, from each signal line to the reference potential. f A first trace 1152, shown in black, and a second trace 1154, shown in grey, are connected by a via 1153 in the flex circuit. In another embodiment, the differential transmission line may be periodically "twisted" to cancel stray electric field pickup.

[0046] FIG. 17 shows an embodiment of a shunt with a Rogowski coil in a busbar embodiment, where the Rogowski coil is sandwiched within the folded busbar shunt. Busbar shunt 1170 has a resistive portion 1172. The shunt is folded in half to lower insertion inductance, and two screw terminals such as 1173 are placed on the same axis, with a flexible circuit 1177 between the folded halves. One sense lead 1174 is connected to one side of the shunt over the top perimeter, and the other sense lead is connected to the other side of the shunt over the bottom perimeter, hidden in this view. An angle pin connector 1178 at the end of a portion 1176 of the flexible circuit connects it to an isolation barrier or probe head. Traces on the flexible circuit and compensation pole components of the Rogowski coil are not shown.

[0047] FIG. 18 shows one embodiment of a surface mounted shunt with a flexible circuit 1180 underneath the surface mounted shunt and between the shunt and the return path in the circuit board on which the shunt is mounted. The shunt has a metal portion 1182 and a resistive portion 1184. Each of the sense leads (e.g., 1183) goes over the top of the shunt via a portion 1181 of the flexible circuit 1180 and connects to each of the metal portions (e.g., 1182) on either side of the shunt. In this view, the flexible circuit traces that form the Rogowski coil are shown at 1186. Although not shown, these traces continue up the flexible circuit 1180 to the compensation pole components and square pin connector 1188.

[0048] Many modifications and variations exist. For example, the filter resistor R f may act as the termination of the transmission line between the shunt / coil and the filter, allowing the probe head to be placed some distance from the shunt while still maintaining high bandwidth. This allows the shunt to be placed very close to the load without giving the probe head any extra space, thereby minimizing insertion inductance.

[0049] The Rogowski coil does not require high voltage insulation and may be placed very close to the shunt because the Rogowski coil wraps around the shunt and is connected directly to the shunt, which further reduces the coil inductance by keeping the coil as short as possible.

[0050] If the return current path is well defined, such as a surface mounted shunt on the return plane layer in the PCB, the self-inductance of the Rogowski coil can be further minimized by shortening the coil so that it only covers the space between the shunt and the return path, rather than completely encircling the shunt. Because the magnetic field is strongest inside the current loop, this arrangement achieves nearly the same mutual inductance as complete encirclement, but with significantly less self-inductance. This configuration also eliminates the vias in the tight bends around the sides of the shunt that are used to mount the coil in a flex circuit, reducing the possibility of via cracking.

[0051] The compensation filter time constant can be determined by any combination of several methods: R The shunt and Rogowski coil may be constructed together as a single unit with appropriate component values, which may take the form shown in Figures 17 or 18, for example.

[0052] Another embodiment provides for the selection of a fixed time constant filter appropriate for a given shunt and Rogowski coil pair. This may be implemented in the form of filter blocks 1146 and 1156 in Figures 15A and 16A, respectively. In yet another embodiment, the filter block is f Alternatively, one may provide one or more programmable filters, such as by using FETs to switch in capacitors in a capacitor DAC. The resistance of the filter, R, is related to the self-inductance of the Rogowski coil. f The response pole due to the load is C f In yet another embodiment, the area or pitch of the Rogowski loop may be tapered along the length of the coil, so that the mutual inductance M can be reduced by sliding an appropriate portion of the tapered coil under the shunt. R may be adjusted.

[0053] For the system shown in FIG. 13, the signal obtained from the probe can be manipulated as it enters the test and measurement equipment to determine the time constant and M R / R. For example, the filter 1116 applied after the signal is acquired by the probe may take the form of a DSP pole-zero filter applied to the acquired waveform to cancel any remaining mismatch in filter time constants. In addition, at frequencies where the skin effect begins to significantly change the effective resistance R, if M R If the ·di / dt term does not sufficiently dominate the R·I term, a filter 1116, consisting of an analog or DSP filter, may be applied to compensate for the resulting error in the crossover region between the shunt-dominated and Rogowski-dominated responses.

[0054] FIG. 19 shows an embodiment of a washer-type current shunt 1200 similar to that described above. The present embodiment has a Rogowski coil within the washer-type current shunt, which surrounds a resistor. The structure has a top conductive contact layer 1202, one or more insulating layers 1204, a Rogowski coil 1206, a resistive core 1208, and a bottom conductive contact layer 1210. The current measurement device in this embodiment has a resistive core with an opening 1214 through which a screw is inserted, from the top surface of the core to the opposite surface (top to bottom as shown). There are many different ways to provide a Rogowski coil, but as with other structures that house a Rogowski coil within a washer-type current shunt, one possible embodiment would be to manufacture the Rogowski as a printed circuit board (PCB).

[0055] As with the other Rogowski coil and shunt resistor embodiments discussed above, the signals from the Rogowski coil and shunt resistor may be combined by the test and measurement instrument. This combination includes placing the coil in series with the shunt resistor or combining the two signals by adding them together. The shunt resistor and coil can be wired in parallel and the combination of their signals applied by the test and measurement instrument.

[0056] Figure 20 shows a more detailed view of the resistive core and one of the conductive surfaces. As shown, resistive core 1208 has a contact area on end face 1216 of the core. The other end face has the same contact area. An insulating layer surrounds the periphery of the resistive core to the outside, similar to a coil structure, allowing the core to contact the conductive surfaces.

[0057] 21 shows a more detailed view of the Rogowski coil 1206. In this view, one can see the electrical contacts, such as 1218. These allow the connection of a resistive core at one contact with a measurement lead at the other contact in a series configuration, as will be shown in more detail below.

[0058] FIG. 22 shows a more detailed view of the resistive core 1208. The resistive core has a height "h" and a wall thickness "t". The wall thickness determines the electrical skin depth of the coil. The electrical skin depth determines the frequency at which the current measuring device enters a mode where the Rogowski coil becomes active. As mentioned above, the shunt resistor is active from DC down to low frequencies. As the frequency of the signal increases, the Rogowski coil becomes active. The choice of wall thickness determines the effective measurement bandwidth.

[0059] 23 shows an assembled current measuring device with conductive layers 1202 and 1210 in contact with a resistive core 1208. A Rogowski coil structure 1206 is separated from the conductive layers by one or more insulators 1204, and the entire assembly has a central opening 1214 that allows for the insertion of a screw or other fastener.

[0060] The contacts of the Rogowski coil are electrically connected to the resistive core, and the Rogowski coils can be arranged in series in a variety of ways. In a first embodiment, one of the electrical contacts on the coil structure is connected to one of the conductive layers by a sense lead 1220. One example shown in FIG. 23 uses the top conductive surface. The other electrical contact has a measurement lead 1222. The other measurement lead 1224 is electrically connected to the other conductive surface of the coil structure.

[0061] Alternatively, there may be gaps or slots in the insulating layer. In one embodiment, the insulating layer has the shape of the letter "C". This allows the connection of measurement lead 1226 to the electrical contact of the Rogowski coil to come directly from the top surface of the resistive core. Measurement lead 1222 is identical, while the other measurement lead 1228 would contact the resistive core directly and exit through a slot or gap in the bottom insulating layer as currently shown.

[0062] In this way, a washer-type current shunt with a shunt resistor and Rogowski coil can be provided in a form factor that allows for the insertion of a fastener.

[0063] In another embodiment, the Rogowski coil is present in a flexible circuit board as described above, but in a multi-layer embodiment that allows for better cancellation of magnetic fields. FIG. 24 shows a flexible board 1230 having multiple layers. A first layer 1232, indicated by a set of single hash marks, has a first set of coil traces and contacts such as 1238 that define vias between the various layers. A second layer 1234, indicated by a single hash mark in the opposite direction, has a second set of coil traces and contacts for the other "end" of the vias. These first and second sets of coil traces are configured such that one set overlaps the other set in the first dimension. The coil structure is connected to a shunt resistor in any of the ways described above.

[0064] In this view orientation, as seen in the upper right corner, the x-direction or dimension is left to right or right to left across the page, the y-direction or dimension runs from top to bottom or bottom to top of the page, and the z-direction or dimension is into and out of the page. The view of the substrate is a top view looking down onto the page. In this example, this is the dimension where the first and second coil traces at least partially overlap. Areas such as 1236 where the overlap occurs are cross-hatched.

[0065] These two sets of coil traces form a Rogowski coil. Vias such as 1238 between the first and second layers, a series and a first junction of the first coil trace, and a series and a second junction of the second coil trace form a Rogowski coil, with either the first or second junction connected to a shunt resistor. In the embodiment of FIG. 24, the Rogowski coil has a single ended output signal. The board has sense leads connected to the Rogowski coil and configured similarly as shown in the previous embodiment above.

[0066] The embodiment of Figures 24-28 has the advantage that there are no current loop areas in the dimensions perpendicular to the coil structure, which allows for improved cancellation and more accurate measurements.

[0067] FIG. 25 shows an embodiment of a third layer 1240, represented by a central trace. This third layer provides mechanical stability to the structure. It prevents the coil structure from collapsing and holds the other two layers in a generally planar orientation. Additionally, the third layer trace in the center of the coil acts as a return current path. This central trace may be wider than the other traces to provide its mechanical stability.

[0068] Figures 26-28 show an embodiment where the Rogowski coil has a differential output signal. The overlapping relationship of the two coils defines how the coil operates. The coils are defined by vias from the top to the bottom of the figure. In the embodiment of Figure 26, the vias define the A coil and the B coil, where the coils have an ABAB pattern when viewed from the top down the page along the z direction. Each coil structure is slightly offset from each other in the x direction. The traces form opposing loops around the outside of the coil, which serve to locally cancel the magnetic field in the z direction.

[0069] In Figure 27, the vias from top to bottom are associated with the coil in an ABBA pattern. This results in a coil structure that is centered in the x direction but has different dimensions in the y direction. The traces form opposing loops around the outside of the coil, locally canceling the magnetic field in the z direction.

[0070] Figure 28 shows a coil configuration where the coils again have an ABBA configuration, being centred in the x direction but different in the y direction. The traces that go around the outside of the coil serve to cancel the magnetic field in the z direction, but each loop at the farthest end of the coil in the y direction has its complement at the farthest end of the other. This results in magnetic field cancellation over a longer distance than the local cancellation embodiment described above.

[0071] FIG. 29 shows an embodiment of the coil structure 1250 mounted on a rigid substrate such as ceramic or glass. This type of substrate offers the advantages of surface mount technology (SMT) as well as the possibility of manufacturing the coil structure at wafer level using thin and thick film processes. Dicing is then performed to produce the individual current measuring devices. FIG. 29 shows a detailed view of the conductive structure without the substrate.

[0072] The coil structure has metal traces (such as 1252) on a first side of a rigid substrate. Vias (such as 1254) connect these traces with traces (such as 1256) on the bottom side, thereby forming the coil structure. Contact pads such as 1258 and 1260 allow connection to measurement leads. As described below, the shunt resistor is typically mounted on the top side. Note that the references to top and bottom refer to the respective orientations shown in the figures. Although not shown in FIG. 29, there may be a central trace similar to 1240 in FIG. 25 that runs through the center of the coil structure and provides a return path.

[0073] In one embodiment, a discrete SMT resistor is laminated or otherwise mounted onto the coil substrate by soldering, gluing, etc. to an exposed pad. In any embodiment, a resistor may be mounted over the central axis of the coil structure to provide a return path. A thin film resistive material or solder mask prevents the coil from shorting to the resistor. In FIG. 30, the resistor 1262 is shown at the top of the image, and the Rogowski coil structure 1250 and its substrate are shown at the bottom of the image. Traces on the substrate surface, the shape of a portion of the coil, contact pads 1258 and 1260 providing the Kelvin sense, and their counterparts are shown.

[0074] Alternatively, the thin film process for forming the coil can be modified to include the shunt resistor. After the coil is formed in the substrate, as shown in Figure 31, an insulating layer 1264 can be deposited over the coil structure. A resistive layer 1266 would then be deposited over the insulator to connect to the conductive surface. This process is suitable for wafer level thin and thick film processing.

[0075] Figure 32 shows a current and magnetic field diagram for a current monitor including a shunt resistor and Rogowski coil in a rigid substrate. Arrows such as 1268 indicate current flow, while dark shading such as 1273 represents conductive material including coil structure 1274. Measurement contacts are shown at 1271 and 1272. Resist 1270 sits on insulator 1269. Magnetic field lines are shown as black dots such as 1276. The magnetic field lines represented by the black dots can be anywhere within the current loop indicated by the arrows.

[0076] FIG. 33 shows a method for fabricating a Rogowski coil in a rigid substrate. The substrate is masked and patterned at 1280 with a via pattern. Typically, the mask covers the portion of the substrate to be retained and the exposed portion is removed, but it can be the other way around. If the substrate is glass, the substrate is baked at 1282 to convert the exposed areas to ceramic. If the substrate is ceramic, this step is not necessary. Next, the portions of the substrate defined by the masking and patterning steps are removed to form the vias at 1274. Next, a conductive material is deposited in the vias, such as by plating, at 1286. Then, a thicker metal layer is deposited on both the top and bottom surfaces of the substrate at 1288. This is then masked, patterned, and processed, such as by etching, at 1290 to form the coil traces connecting the vias, as well as the contact pads and other conductive features. At 1292, the shunt resistors are connected by lamination and soldering / gluing or deposition of insulating and resistive layers as described above. Working Example

[0077] In the following, examples useful for understanding the technology disclosed in the present application are presented. The embodiment of the technology may include one or more of the examples described below and any combination thereof.

[0078] Example 1 is a current measuring device comprising: a shunt resistor having a plurality of measurement leads, including a resistive core with an opening, configured to be positioned in a current path to be measured; a Rogowski coil having electrical contacts and surrounding the resistive core; a conductive layer on a first side of the resistive core, a conductive layer on a second side of the resistive core opposite the first side, and one or more insulating layers between each of the conductive layers and the Rogowski coil, wherein the current measuring device is configured to combine signals from the shunt resistor and the Rogowski coil.

[0079] Example 2 is the current measuring device of Example 1, wherein the current measuring device is configured to combine signals by either placing the Rogowski coil in series with the measurement lead or by adding a signal from the shunt resistor and a signal from the Rogowski coil.

[0080] Example 3 is a current measuring device of either Example 1 or 2, wherein the resistive core is electrically connected to one of the electrical contacts of the Rogowski coil, and another of the electrical contacts of the Rogowski coil is electrically connected to a first measurement lead among the plurality of measurement leads.

[0081] Example 4 is the current measuring device of Example 3, wherein the resistive core is electrically connected to one of the electrical contacts of the Rogowski coil via the conductive layer on the first surface of the resistive core.

[0082] Example 5 is the current measuring device of Example 3, wherein the resistive core is directly electrically connected to one of the electrical contacts of the Rogowski coil through a gap in the one or more insulating layers.

[0083] Example 6 is a current measuring device of any of Examples 1 to 5, wherein one of the plurality of measurement leads is either electrically connected to the resistive core via the conductive layer on the second surface of the resistive core or directly electrically connected to the resistive core via a gap in the one or more insulating layers.

[0084] Example 7 is the current measuring device of any of Examples 1 to 6, wherein the resistive core has a wall thickness selected to set the frequency at which the Rogowski coil becomes active.

[0085] Example 8 is the current measuring device of any of Examples 1 to 7, wherein the Rogowski coil comprises a coil within a printed circuit board.

[0086] Example 9 is a current measuring device comprising a shunt resistor having a sense lead and configured to be placed in a current path to be measured, and a Rogowski coil on a flexible substrate at least partially surrounding the shunt resistor, the current measuring device configured to combine signals from the shunt resistor and the Rogowski coil.

[0087] Example 10 is the current measuring device of example 9, wherein the Rogowski coil is configured such that there is no loop region in a dimension perpendicular to the Rogowski coil.

[0088] Example 11 is a current measuring device of any of Examples 9 or 10, wherein the Rogowski coil comprises a first layer of the flexible substrate including a first coil trace series and a first contact, a second layer of the flexible substrate including a second coil trace series and a second contact at least partially overlapping the first coil trace series and the first contact in the z-direction, and a via between the first layer and the second layer, wherein the first coil trace series and the first contact and the second coil trace series and the second contact form a Rogowski coil, and either the first contact or the second contact is connected to the shunt resistor.

[0089] Example 12 is the current measuring device of example 12, further comprising a third layer between the first layer and the second layer.

[0090] Example 13 is the current measuring device of example 12, wherein the third layer includes a central trace of the Rogowski coil serving as a return path.

[0091] Example 14 is the current measurement device of Example 12, wherein the third layer is configured to provide mechanical stability to the flexible substrate, including being wider than other traces in the flexible substrate.

[0092] Example 15 is the current measurement device of any of examples 9 to 14, wherein the current measurement device is configured to generate a single-ended output signal.

[0093] Example 16 is the current measuring device of any of examples 9 to 15, wherein the current measuring device is configured to generate a differential output signal.

[0094] Example 17 is a current measuring device of Example 16, wherein the first coil trace series overlaps the second coil trace series, and the first contacts and the second contacts form an alternating ABAB pattern in a y-direction dimension to locally cancel a magnetic field in the first dimension.

[0095] Example 18 is the current measuring device of Example 16, wherein the first coil trace series overlaps the second coil trace series, and the first contact and the second contact form an ABBA pattern centered in the x direction and diverse in the y direction, to locally cancel a magnetic field in the first dimension.

[0096] Example 19 is the current measuring device of Example 16, wherein the first coil trace series overlaps the second coil trace series, and the first contact and the second contact form an ABBA pattern with loops centered in the x direction and facing each other at the farthest ends in the y direction, canceling magnetic fields at a greater distance than locally canceling coils.

[0097] Example 20 is a current measuring device comprising a rigid substrate having a top surface and a bottom surface, a via penetrating the rigid substrate from the top surface to the bottom surface and filled with a conductive material, conductive layers on the top surface and bottom surface connected to the via to form a Rogowski coil structure, one or more insulating layers disposed directly on the Rogowski coil structure, a shunt resistor disposed directly on the one or more insulating layers, and a measurement contact on the bottom surface.

[0098] Example 21 is the current measuring device of Example 20, wherein the rigid substrate is made of either glass or ceramic.

[0099] Example 22 is a current measuring device of either Example 20 or 21, wherein at least one of the one or more insulating layers is present on the top surface of the rigid substrate and has an exposed contact pad electrically connected to the Rogowski coil structure, and the shunt resistor is present in an insulating layer on the top surface of the rigid substrate and is electrically connected to the exposed contact pad.

[0100] Example 23 is the current measuring device of any of Examples 20 to 22, wherein the shunt resistor is centered on a central axis of the Rogowski coil structure.

[0101] Example 24 is the current measuring device of any of Examples 20 to 23, wherein the current measuring device further comprises a conductive trace passing through a center of the Rogowski coil structure to provide a return path.

[0102] Example 25 is the current measuring device of any of Examples 20 to 24, wherein at least one insulating layer of the one or more insulating layers is present on a top surface of the rigid substrate, and the shunt resistor is disposed on the at least one insulating layer and includes a layer of resistive material in contact with a conductive layer on the top surface.

[0103] Example 26 is a method for manufacturing a current measurement device, comprising the steps of masking a rigid substrate with a via pattern, removing a portion of the rigid substrate to form a hole through the rigid substrate, depositing a conductive material in the hole to form a conductive via, depositing a second layer of conductive material on a top and bottom surface of the rigid substrate to connect the vias to form a coil pattern and to form measurement contacts on one side of the rigid substrate, masking and patterning the second layer of conductive material on the top and bottom surfaces to connect the vias to form a Rogowski coil structure and to form contact pads on the top surface, and connecting a shunt resistor to the Rogowski coil structure.

[0104] Example 27 is the method of manufacturing example 26, wherein the rigid substrate comprises glass, and masking the rigid substrate with a via pattern comprises heat treating (baking) the rigid substrate to convert exposed areas to ceramic before removing portions of the rigid substrate.

[0105] Example 28 is the method of any of Examples 26 or 27, wherein connecting the shunt resistor includes attaching a surface mount resistor to the contact pad.

[0106] Example 29 is the method of any of Examples 26 to 28, wherein the process of connecting the shunt resistor includes depositing one or more insulating layers on the Rogowski coil structure and depositing a resistive material on the one or more insulating layers.

[0107] Example 30 is the manufacturing method of any of Examples 26 to 29, further comprising passivating the second layer of conductive material on the top and bottom surfaces before connecting the shunt resistor.

[0108] Example 31 is a manufacturing method of Examples 26 to 30, in which a plurality of current measuring devices are manufactured at a wafer level and then diced to manufacture individual current measuring devices.

[0109] For purposes of illustration, specific embodiments of the invention have been illustrated and described, but it will be understood that various modifications can be made without departing from the spirit and scope of the invention. Accordingly, the invention should not be limited, except as by the appended claims.

[0110] In addition, the description of this application refers to specific features. It is to be understood that the disclosure herein includes all possible combinations of those specific features. For example, if a specific feature is disclosed in connection with a particular embodiment, that feature can also be used in connection with other embodiments, to the extent possible.

[0111] Furthermore, when the application refers to a method having two or more defined steps or processes, those defined steps or processes may be performed in any order or simultaneously, unless the context precludes such a possibility.

[0112] All features disclosed in the specification, claims, abstract and drawings, and all steps in any disclosed method or process, may be combined in any combination, except where at least some of such features or steps are mutually exclusive combinations. Each feature disclosed in the specification, abstract, claims and drawings may be replaced by an alternative feature serving the same, equivalent or similar purpose, unless expressly stated otherwise.

[0113] For purposes of illustration, specific embodiments of the invention have been illustrated and described, but it will be understood that various modifications can be made without departing from the spirit and scope of the invention. Accordingly, the invention should not be limited, except as by the appended claims. [Explanation of symbols]

[0114] 110 Volts 300 Shunt 302 Resistance section 304 Insulation 306 Opening 310 Busbar 320 screw terminal 322 Threaded part 330 Current Path 340 First Contact 350 Insulating Shoulder Washer 352 Pin 354 Pin 360 Second Contact 600 Shunt 602 Resistance section 604 Insulation 700 Shunt 702 Resistance section 704 Insulation 710 First detection lead 712 Second detection lead 714 1st Slot 716 2nd Slot 720 First conductive element 722 Second conductive element 730 No. 1 Compressible Conductive Gasket 732 Second compressible conductive gasket 740 Washer 900 Shunt 902 Resistance section 904 Insulation 910 First detection lead 912 Second detection lead 920 First conductive element 922 Second conductive element 924 1st Clip 926 2nd Clip 930 Flexible Circuit 932 resistor 1000 Shunt 1002 Resistance section 1004 Insulation part 1006 Hexagonal Conductive Element 1008 Second detection lead 1012 First detection lead 1032 resistor 1110 Device Under Test (DUT) 1112 Current measuring device 1114 Probe 1116 Filter 1118 Processor 1120 Test and measurement equipment 1125 Test and Measurement System 1130 Shunt 1132 Resistance section 1134 Detection Lead 1136 Resistance section 1140 Shunt 1141 Rogowski Coil 1142 1st Trace Set 1143 Beer 1144 2nd Trace Set 1146 Fixed time constant single pole compensation circuit 1148 Transmission Line 1150 Shunt 1151 Rogowski Coil 1152 1st Trace Set 1153 Beer 1154 2nd Trace Set 1156 Compensation pole 1158 Reference potential line 1160 Transmission Line 1170 Busbar Shunt 1172 Resistance section 1173 Screw Terminal 1174 Detection lead wire 1176 Part of a flex circuit 1177 Flex Circuit 1178 Square Pin Connector 1180 Flex Circuit Shunt 1181 Part of a flex circuit 1182 Metal Part 1183 Detection lead wire 1184 Resistance section 1186 Rogowski Coil 1188 Square Pin Connector 1200 Washer Current Shunt 1202 Top conductive contact layer 1204 One or more insulating layers 1206 Rogowski Coil 1208 Resistive Core 1210 Bottom conductive contact layer 1214 Opening 1216 Core end face 1218 Electrical contacts 1220 Detection lead wire 1222 Measurement lead wire 1224 Measurement lead wire 1226 Rogowski coil electrical contacts on measuring leads 1228 Measurement lead wire 1230 Flexible PCB 1232 1st layer 1234 2nd layer 1236 area 1238 Contact (via) 1240 3rd layer 1250 Coil Structure 1252 Metal Trace 1254 Beer 1256 Trace 1258 Contact Pad 1260 Contact Pad 1262 resistor 1264 Insulating layer 1266 Resistance layer 1268 Current Flow 1269 Insulator 1270 Resist 1271 Measurement junction 1272 Measuring junction 1273 Conductive materials 1274 Coil Structure 1276 Magnetic Field Lines

Claims

1. a shunt resistor having a plurality of measurement leads, the shunt resistor including a resistive core with an aperture, the shunt resistor configured to be placed in a path of a current to be measured; a Rogowski coil having electrical contacts and surrounding the resistive core; a conductive layer on a first surface of the resistive core; a conductive layer on a second surface of the resistive core opposite the first surface; one or more insulating layers between said conductive layers and the Rogowski coil; Equipped with A current measuring device configured to combine signals from the shunt resistor and the Rogowski coil.

2. 2. The current measuring device of claim 1, wherein the resistive core is electrically connected to one of the electrical contacts of the Rogowski coil through the conductive layer on the first surface of the resistive core.

3. 2. The current measuring device of claim 1, wherein the resistive core is directly electrically connected to one of the electrical contacts of the Rogowski coil through a gap in the one or more insulating layers.

4. 2. The current measuring device of claim 1, wherein one of the plurality of measurement leads is either electrically connected to the resistive core through the conductive layer on the second surface of the resistive core or directly connected to the resistive core through a gap in the one or more insulating layers.

5. 2. The current measuring device of claim 1, wherein the resistive core has a wall thickness selected to set the frequency at which the Rogowski coil becomes active.

6. a shunt resistor having sense leads and configured to be placed in a path of a current to be measured; a Rogowski coil on a flexible substrate at least partially surrounding the shunt resistor; Equipped with A current measuring device configured to combine signals from the shunt resistor and the Rogowski coil.

7. 7. The current measurement device of claim 6, wherein the Rogowski coil is configured such that there are no loop regions in a dimension perpendicular to the Rogowski coil.

8. The Rogowski coil is a first layer of the flexible substrate including a first series of coil traces and a first contact; a second layer of the flexible substrate including a second series of coil traces and second contacts at least partially overlapping in the z-direction with the first series of coil traces and the first contacts; a via between the first layer and the second layer; Equipped with 7. The current measuring device of claim 6, wherein the first coil trace series and the first contact and the second coil trace series and the second contact form a Rogowski coil, and either the first contact or the second contact is connected to the shunt resistor.

9. 9. The current measuring device of claim 8, further comprising a third layer between the first layer and the second layer, the third layer configured to provide mechanical stability to the flexible substrate, including being wider than other traces in the flexible substrate.

10. 9. The current measurement device of claim 8, wherein the first series of coil traces overlap the second series of coil traces, and the first and second contacts form an alternating A-B-A-B pattern in a y-dimension to locally cancel a magnetic field in the first dimension.

11. 9. The current measurement device of claim 8, wherein the first series of coil traces overlap the second series of coil traces such that the first and second contacts form an A-B-B-A pattern centered in the x direction and diverse in the y direction, providing localized cancellation of a magnetic field in a first dimension.

12. 9. The current measurement device of claim 8, wherein the first series of coil traces overlap the second series of coil traces, and the first and second contacts form an A-B-B-A pattern with loops centered in the x direction and facing each other at their farthest ends in the y direction, canceling magnetic fields at a greater distance than locally canceling coils.

13. a rigid substrate having a top surface and a bottom surface; a via extending through the rigid substrate from the top surface to the bottom surface and filled with a conductive material; a conductive layer on the top and bottom surfaces connected to the vias to form a Rogowski coil structure; one or more insulating layers disposed directly on said Rogowski coil structure; a shunt resistor disposed directly on the one or more insulating layers; The measurement contacts on the bottom surface A current measuring device comprising:

14. 14. The current measuring device of claim 13, wherein at least one of the one or more insulating layers is present on the top surface of the rigid substrate and has exposed contact pads electrically connected to the Rogowski coil structure, and the shunt resistor is present in an insulating layer on the top surface of the rigid substrate and electrically connected to the exposed contact pads.

15. 14. The current measuring device of claim 13, wherein at least one of the one or more insulating layers is present on a top surface of the rigid substrate, and the shunt resistor is disposed on the at least one insulating layer and includes a layer of resistive material in contact with a conductive layer on the top surface.

16. masking the rigid substrate with the via pattern; removing a portion of the rigid substrate to form a hole through the rigid substrate; depositing a conductive material into the hole to form a conductive via; depositing a second layer of conductive material on the top and bottom surfaces of the rigid substrate to connect the vias to form a coil pattern and to form measurement contacts on one side of the rigid substrate; masking and patterning the second layer of conductive material on the top and bottom surfaces to connect the vias to form a Rogowski coil structure and to form contact pads on the top surface; connecting a shunt resistor to the Rogowski coil structure; A method for manufacturing a current measuring device comprising the steps of:

17. 17. The method of claim 16, further comprising passivating the second layer of conductive material on the top and bottom surfaces before connecting the shunt resistor.

Images