Current monitor combining shunt resistor with Rogowski coil

Abstract

A current monitor combines a shunt resistor with a Rogowski coil. A current measuring device has: a shunt resistor having an opening and a resistive core of a measuring lead; a Rogowski coil having an electrical contact surrounding the resistor core; a conductive layer on the first and second sides of the resistive core; and one or more insulating layers between the conductive layer and the Rogowski coil, the current measurement device configured to combine signals from the shunt resistor and the Rogowski core. The current measurement device may have a Rogowski coil on a flexible substrate, the Rogowski coil at least partially wound around a shunt resistor. The current measuring device includes: a rigid substrate; a via filled with a conductive material through the rigid substrate; a conductive layer connected to the via to form a top surface and a bottom surface of the Rogowski coil structure; one or more insulating layers directly on the coil structure; and a shunt resistor directly on the one or more insulating layers.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] The present disclosure is a continuation-in-part of U.S. non-provisional patent application No. 18 / 198,800, filed on May 17, 2023, entitled “SHUNT FOR USE IN BUSBAR-TO-MODULE CONNECTIONS,” which claims the benefit of U.S. Provisional Application No. 63 / 400,831, filed on August 25, 2022, entitled “LOW INSERTION INDUCTANCE HIGH-POWER BUSBAR CURRENT SHUNT,” and U.S. Provisional Application No. 63 / 344,981, filed on May 23, 2022, entitled “COAXIAL SHUNT FOR USE INBUSBAR-TO-MODULE CONNECTIONS.” The present disclosure is also a continuation-in-part of U.S. non-provisional application No. 18 / 225,034, filed on July 21, 2023, entitled “CURRENT MONITOR COMBINING A SHUNT RESISTOR WITH AROGOWSKI COIL,” which claims the benefit of U.S. provisional application No. 63 / 392,471, filed on July 26, 2022, entitled “CURRENT MONITOR COMBINING A SHUNT RESISTOR WITH A ROGOWSKI COIL.” The present disclosure also claims the benefit of U.S. Provisional Application No. 63 / 515,570, filed on July 25, 2023, entitled “WASHER SHUNT WITH A ROGOWSKI COIL FOR MEASURING CURRENT IN A DEVICE UNDERTEST,” U.S. Provisional Application No. 63 / 516,093, filed on July 27, 2023, entitled “CURRENT MONITOR COBINING A SHUNT RESISTOR WITH A ROGOWSKI COIL USING THIN FILM PROCESS,” and U.S. Provisional Application No. 63 / 580,970, filed on September 6, 2023, entitled “FLEX CIRCUIT INCLUDINGA ROGOWSKI COIL.” The disclosures of all of the above-referenced applications are incorporated herein by reference in their entirety. Technical Field

[0003] The present disclosure relates to test and measurement systems, and more particularly to apparatus and methods for measuring or monitoring electrical current. Background Art

[0004] High power switchgear is usually built in module form with screw terminals for connection to busbars for high current terminals. To support the rapid current changes during switching transients, capacitor banks are usually mounted on the busbars, and often close to the modules to minimize series inductance. This then leads to difficulties when inserting current measurement equipment between the capacitor bank and the module to measure the switching transients, as it may insert so much inductance that it changes the transient being measured.

[0005] Various approaches have addressed this problem, but all have their own drawbacks. For example, one solution employs Rogowski coils around the busbars. Rogowski coils lack DC capability, have limited bandwidth, and may have accuracy issues depending on the location of the coils. Similarly, another solution uses current transformers around the busbars and the extension poles between the modules. However, current transformers, in addition to lacking DC capability, may also add inductance and typically have limited bandwidth.

[0006] Another approach is to insert a coaxial shunt into the gap in the busbar. Typically, these coaxial shunts have three concentric conductors in a cylindrical shape: a return path on the outside, a resistive shunt material in the middle, and a sensing lead extending through the innermost portion of the coaxial shunt. Such coaxial shunts constrain the magnetic field between the outside and the middle material to offset any inductance affecting the sensing lead, and they allow DC coupling and wide measurement bandwidth. However, these shunts may be difficult to insert into the gap in the busbar, and may extend the electrical path, inserting unwanted inductance in the current path.

[0007] Large and rapidly changing currents, such as those commonly found in switching power supplies and motor drives using wide-bandgap semiconductors (as well as in lightning or other arc discharges), are notoriously difficult to measure accurately.

[0008] A common method is to place a series resistor (or "shunt") in the current path, measure the voltage drop caused by the current, and then divide by the resistance. This method handles DC and lower frequencies well, but suffers at higher frequencies due to the inductive drop across the shunt. For frequency f c Above this frequency, the inductor voltage drop exceeds the resistor voltage drop:

[0009]

[0010] When measuring large currents, a relatively small shunt resistor R is required to keep the voltage drop and power dissipation across the shunt within reasonable limits, which results in a usable bandwidth f c Inappropriately (objectionably) low.

[0011] The inductive voltage drop can be eliminated by using a coaxial shunt, where the resistive element is a cylinder, the return current passes through a larger and concentric outer cylinder, and the voltage measurement lead is taken out of the shunt inside the resistive cylinder. The symmetrical nature and external return current path ensure that the magnetic field generated by the current circulates between the shunt and the external return path, leaving no magnetic field to produce an inductive voltage drop on the measured voltage inside the shunt. Coaxial shunts eliminate the measured inductance (the inductance included in the measured voltage drop), but require a longer current path through the shunt, thereby increasing the insertion inductance (the inductance inserted into the current path of the system being measured). Even without the measured inductance, coaxial shunts have limited bandwidth due to the skin effect of the shunt material. As frequency increases, the skin depth of the current in the conductor decreases. Once the skin depth approaches the thickness of the resistive cylinder, a significantly reduced portion of the current flows on the inside of the shunt, resulting in a smaller resistive voltage drop on the inside where the voltage is measured.

[0012] Another method for increasing the usable bandwidth of a shunt is to add a cancelling mutual inductance M in the lead dressing of the voltage measuring leads of a conventional shunt. c :

[0013]

[0014] This minimizes insertion inductance by not requiring a specific return current path, but is more difficult to implement because the return current path must still be known to determine lead placement to achieve cancellation (M C = L). This cancellation method also suffers at high frequencies due to the skin effect: when the skin depth approaches the shunt thickness, the current path through the shunt will be physically shifted, changing M C , L and R.

[0015] Another current measurement method is to sense the magnetic field along a closed loop around the current to be measured. The Rogowski coil senses the time derivative of this magnetic field; the voltage induced across the Rogowski coil can then be integrated to determine the current. Rogowski coils have the advantages of inherent isolation and relative ease of installation, but cannot measure DC currents. In fact, there is a trade-off between the low-frequency usable range and high-frequency bandwidth of the Rogowski coil. Achieving low-frequency coverage means that the mutual inductance between the coil and the current is large to maximize the coil voltage at low di / dt, while high bandwidth means that the self-inductance of the coil is small to minimize its time constant of the load impedance driving the integrator.

[0016] The configuration of the disclosed technology solves the shortcomings of the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1A The screw terminals of the switchgear module are shown.

[0018] Figure 1B Additional examples of screw terminals of a switchgear module are shown.

[0019] Figure 2 An example of a conventional coaxial shunt is shown.

[0020] Figure 3 A cross-sectional view of the bus bar and module connections of an embodiment with a shunt as inserted is shown.

[0021] Figure 4 Shows Figure 3 Top view of the busbar and module connections.

[0022] Figure 5 Shows Figure 3 A cross-sectional view of the components of a flow diverter.

[0023] Figure 6 A cross-sectional view of another embodiment of a flow splitter is shown.

[0024] Figure 7 An embodiment of a flow splitter is shown.

[0025] Figure 8 and 9 An alternative embodiment of a flow diverter is shown.

[0026] Fig.10 Views and embodiments of a flow diverter are shown.

[0027] Fig.11 Views showing components of an embodiment of a flow splitter are shown.

[0028] Fig.12 Shows Fig.11 View of the shunt.

[0029] Fig.13 A block diagram of a current measurement accessory within a test and measurement system is shown.

[0030] Figures 14A-14D Different embodiments of current shunts are shown.

[0031] Fig.15 An embodiment of a current shunt in combination with a Rogowski coil is shown.

[0032] Fig.16 An alternative embodiment of a current shunt in combination with a Rogowski coil is shown.

[0033] Fig.17 An embodiment of a current shunt in combination with a Rogowski coil for installation in a bus bar is shown.

[0034] Fig.18 An embodiment of a current shunt in combination with a Rogowski coil for surface mounting on a printed circuit board is shown.

[0035] Fig.19 An exploded view of an embodiment of a washer current shunt in combination with a Rogowski coil is shown.

[0036] Fig. 20 The resistive portion and contact plate of an embodiment of a washer current shunt in combination with a Rogowski coil are shown.

[0037] Fig.21 An embodiment of a Rogowski coil is shown.

[0038] Fig. 22 An embodiment of a resistive portion of an embodiment of a washer current shunt is shown.

[0039] Fig.23 An embodiment of an assembled Rogowski coil with an embodiment of measurement leads is shown.

[0040] Figure 24-25 A single-ended embodiment of a Rogowski coil on a flexible substrate is shown.

[0041] Figure 26-28 Different embodiments of Rogowski coils on a flexible substrate are shown.

[0042] Fig.29 An embodiment of a Rogowski coil for a rigid substrate is shown.

[0043] Figure 30-31 A surface mounted embodiment of a Rogowski coil in a rigid substrate is shown.

[0044] Fig.32 Current and magnetic field diagrams showing an embodiment of a current monitor in a rigid substrate.

[0045] Fig.33 A process flow for fabricating a Rogowski coil in a rigid substrate is shown. DETAILED DESCRIPTION

[0046] Embodiments herein relate to a test and measurement accessory device including a shunt configured to be inserted between a bus bar and a module. The accessory device enables measurement of a voltage drop across the shunt and, therefore, using the known resistance of the device, measurement of the current flowing between the bus bar and the module. Some embodiments of the shunt are configured as a washer with a sense lead extending through an interior portion or opening of the shunt. As discussed in further detail below, embodiments of the shunt minimize electrical path length, and therefore minimize inductance inserted into the current path, while maintaining the advantages of the DC capability and wide measurement bandwidth of conventional shunt resistors.

[0047] Figure 1A and 1B A module for a high power switchgear is shown, the module having screw terminals 100 for connecting the module to a bus bar ( Figure 1A and 1B 1 and 1 ). The screw terminal 100 includes a bolt 110 for mechanically attaching the bus bar to the screw terminal 100 and for providing a current path between the module and the bus bar. To support the rapid current changes during switching transients, a capacitor bank can be mounted on the bus bar and the capacitor bank can be mounted close to the module to minimize series inductance. However, this can cause difficulties when inserting a current measurement device between the capacitor bank and the module to measure the switching transient because it may insert so much inductance that it changes the transient being measured.

[0048] Figure 2 A cross section of an example of a conventional coaxial shunt 200 for measuring a voltage drop across the shunt is shown. The shunt includes a coaxial cylinder. The outer cylinder 202 will typically be composed of copper, and the inner cylinder 204 is made of manganese copper. Pins 206 and 208 are current pins, and pins 210 and 212 are voltage pins. The center pin or sense lead 212 is located in the center of the coaxial shunt. The problem that arises with this type of structure is the current path. The current flows through the current pin 206 and along the outer cylinder 202 along the line shown at 214. This relatively long current path increases the total electrical path length of the circuit or device being measured. This inserts inductance into the path, which may change the transient being measured. As discussed below, the embodiments herein minimize any length added to the current path.

[0049] Figure 3 A test and measurement accessory is shown, which includes a Figure 1A and 1B The shunt 300 between the bus bar 310 and the screw terminal 320 of the module shown in FIG. The screw terminal 320 may be Figure 1A and 1B An example of a screw terminal 100 as shown in FIG. 1 , or similar to Figure 1A and 1B The screw terminals shown in 100, but in Figure 3 300 is shown as elongated to better illustrate the current path through the assembled components. The shunt 300 includes an opening 306, such as a hole extending through the shunt. An embodiment of the shunt 300 is shaped so that it resembles a washer. The shunt 300 with its washer-like shape includes a resistive portion 302, and in some embodiments may also include an insulating portion 304.

[0050] In some embodiments, the resistive portion 302 surrounds the insulating portion 304, thereby forming the outer and inner layers of the shunt 300. The shunt 300 can be between the screw terminal 320 and the bus bar 310, and provide 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 is configured to form a portion of the current path 330. Then, the bolt 110 can be inserted through the bus bar 310 and through the opening 306 of the shunt 300, and fastened to the screw portion 322 of the screw terminal 320. This fixes the shunt 300 between the bus bar 310 and the screw terminal 320, and forms a good electrical contact between these components.

[0051] The bolt 110 can be used as one contact 340 of the shunt to allow sensing of the voltage at the "bottom" end of the shunt 300, the end of which contacts the screw terminal 320. A second contact can be located on or directly connected to the bus bar 310, such as at location 360, to sense the voltage at the "top" end of the shunt 300, the end of which contacts the bus bar 310. The resistive portion 302 causes a voltage drop across the shunt 300, which can be measured at the first and second contacts. The measured voltage drop, together with the known resistance value 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.

[0052] The bolt 110 extends through the opening 306 of the shunt to conveniently serve as a sense lead and provide a contact 340 at the same "top" surface of the assembled accessory device as a second contact 360. The contact 340 and the bolt 110 are electrically isolated from the resistive portion 302 of the shunt. In some embodiments, an insulating portion 304 of the shunt 300 electrically isolates the contact 340 from the resistive portion 302. In some embodiments, an air gap electrically isolates the contact 340 from the resistive portion 302. However, without the insulating layer 304, it may be more challenging to install the shunt 300 and maintain the air gap to prevent the bolt 110 from shorting with the resistive portion 302 of the shunt 300 when the bolt is tightened. Some embodiments include both the insulating portion 304 of the shunt and the air gap.

[0053] Figure 4 Shows Figure 3 310 is a top view of an assembly of a bus bar 310 mechanically fastened to a screw terminal 320 of an electronic module and a shunt 300 inserted therebetween. As discussed, embodiments of the present disclosure may utilize the bolt 110 as one sensing lead of the shunt 300 and the bus bar 310 as another sensing lead, thereby providing a contact surface for making measurements, for example, by connecting a cable, a lead of a test probe, or other measurement leads of a test and measurement instrument. The contacts allow for the measurement of a voltage drop across the shunt, which can then be converted into a current measurement. Nevertheless, the measurement leads contacting the contact surface may be sensitive to magnetic flux from the current flowing through the bus bar, as current crowding on the module side may cause some magnetic field to wrap around through the bolt 110. Therefore, the specific location of the two or more contacts for the measurement leads on the contact surface of the bolt 110 and the bus bar 310 may change the measurement due to the magnetic field wrapping around through the bolt 110.

[0054] For example, Figure 4 As illustrated in FIG, the measurement leads contacting the bolt 110 and the bus bar 310 at a first position 410 (denoted by A' and B') and a second position 420 (denoted by A" and B") can enclose some loop areas that are sensitive to magnetic flux. The positions marked with changes in A exist on the bolt and changes in B exist on the bus bar 310. Because the polarity of the magnetic pickup will change between measurement positions, a third measurement position 430, denoted by A and B, can be used as an intermediate position that experiences minimal magnetic pickup in the measurement leads. The specific location of this third measurement position 430 can depend on factors such as the thickness of the shunt 300 (shown as a dashed line because it is located below the top of the bolt and bus bar 310) and the specific current paths in the bus bar 310 screw terminals 320 of the electronic module.

[0055] However, in general, embodiments will have first and second contacts 340, 360 of sufficient size to allow for some intermediate position for placement of the measurement leads that reduces the effects of magnetic flux. Because the washer-like shape of the shunt 300 maintains a relatively flat profile, it minimizes the additional length of the current path from the shunt 300 compared to conventional shunt components. Minimizing the current path across the shunt 300 in this manner reduces the additional inductance inserted into the current path. Thus, utilizing the shunt 300 and carefully placing the measurement leads can minimize two potential sources of measurement errors in high power switching devices.

[0056] In addition, Figure 3In the embodiment of the shunt 300 shown in FIG. 1 , an insulating shoulder washer 350 may be included. The insulating shoulder washer 350 may be present together with the shunt 300 and may have a portion parallel to the bus bar 310 to be placed between the bolt 110 and the bus bar 310. Figure 5 As shown in FIG. 1 , the insulating shoulder washer 350 may also include conductive portions 356 and 358 to contact the Figure 3 The conductive portions 356 and 358 may include pins 352 and 354. The pins 352 and 354 are Figure 5 denoted by A and B in the figure. Pins 352, 354 can provide connection locations for measuring the voltage between points A and B, which includes the voltage drop across the shunt 300 and the voltage drop due to the contact resistance of the shunt 300 with the bus bar 310 above and the screw terminal 320 below. Pins 352, 354, together with conductive portions 356, 358 and the bus bar 310 and bolt 110, form at least two contacts for measuring the voltage drop across the assembled components. Figure 4 As with the measurement positions described above, before fully tightening the bolt 110 to the screw terminal 320, the user can rotate the shoulder washer 350 to adjust the specific position of the pins 352 and 354 to minimize magnetic flux pickup. Figure 4 and Figure 5 In both examples, the optimum rotational position can be found experimentally by minimizing the high frequency content in the measured voltage. The magnetic pickup (proportional to di / dt) is always orthogonal to the resistor drop, regardless of polarity, and thus the high frequency content can only be artificially increased. Therefore, the minimum high frequency content as a function of rotation coincides with zero magnetic pickup.

[0057] Figure 6 Another example of a shunt 600 is shown. Shunt 600 is similar to shunt 300, including a resistive portion 602 and an insulating portion 604, but includes a Kelvin sensing configuration with a sense lead 610 on the shunt 600 itself. The sense lead 610 is present on an inner portion of the shunt 600, extending parallel to the central axis of the shunt 600, for example, through the insulating portion 604. In this way, having the sense lead 610 on the shunt 600 itself can avoid measuring the voltage across the shunt 600 and the insulating portion 604. Figure 3 The voltage drop of the contact resistance between the bus bar and the module is shown in FIG. 6A . In addition, extending the sense lead 610 through an interior portion of the shunt 600 can minimize magnetic flux pickup.

[0058] The embodiments of the shunts herein each have an opening through which one of the sense leads will extend. While this is similar to the current example of the shunt given above, here the sense lead is configured as part of the current path so that it is not directly connected to the current path. Figure 3The length added to the current path is minimized compared to the length of the current path shown in .

[0059] Figure 7 An embodiment of a shunt 700 is shown. In this embodiment, the shunt 700 may still include a resistive portion 702 and an insulating portion 704. The insulating portion 704 may include a ceramic washer, and the resistive portion 702 may include a resistive material on a surface of the ceramic washer (e.g., as shown, painted on an inner surface of the ceramic washer). An example material for the ceramic washer may be CoorsTek YZTP zirconia, but many other materials may also be used in embodiments to provide a structural substrate for the resistive material. Embodiments may also include first and second conductive elements 720 and 722, wherein the first conductive element 720 is placed on a top surface of the ceramic washer forming the insulating portion 704, and the second conductive element 722 is placed on a bottom surface. The conductive elements 720, 722 may be formed of, for example, gold or other metals, and may be electrically connected to the resistive portion 702 by, for example, solder or brazing. In addition, instead of Figure 7 The screw terminals used as sense leads are not shown, but the first sense lead 710 provides a contact point for the measuring lead and is connected from the nearest Figure 1A and 1B The conductive element 722 on the bottom surface of the electronic module extends to the top of the shunt 700 closest to the bus bar ( Figure 3 ). The conductive material forming the sense lead contact 710 may extend perpendicularly parallel to the central axis of the shunt 700, but be insulated from the coating circuit forming the resistive portion 702. In this manner, the first sense lead extends through an opening in the interior portion of the shunt 700. Figure 7 The sense lead 710 is illustrated with an exaggerated height in FIG, but the sense lead 710 typically extends vertically through the thickness or height of the ceramic gasket.

[0060] The second sense lead 712 provides another contact point formed by extending conductive material from the conductive element 720 on the top surface. The ceramic washer forming the insulating portion 704 may also include a first slot 714 and a second slot 716 for accommodating the first sense lead 710 and the second sense lead 712, respectively. As shown, the conductive element 720 placed on the top surface of the ceramic washer forming the insulating portion 704 may have a gap aligned with the slot 714, which prevents the sense lead 710 from contacting the top conductive element 720. By rotating the shunt 700, the user can position the first sense lead 710 and the second sense lead 712 so that they experience minimal magnetic pickup from the magnetic field surrounding through the shunt 700.

[0061] Figure 7Embodiments may also include at least one compressible conductive gasket 730. For example, a 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. The compressible conductive gasket may be present in either or both of the above configurations and may protect the shunt 700 from the compressive forces of a mechanical attachment, such as the screw forces of a screw terminal. Finally, Figure 7 Embodiments may include at least one conductive locking washer 740. Although Figure 7 A single locking washer 740 is shown placed at the top of the shunt 700, but embodiments may have locking washers at the top or bottom or both. The locking washer(s) may replace one or more of the compressible conductive washers.

[0062] Figure 8 700. As shown, embodiments of the shunt 700 can be assembled with optional compressible conductive washers 730 and 732 on both the top and bottom surfaces of the shunt 700 to protect the insulating portion 704 from compressive forces. Additionally, in embodiments, the second sense lead 712 connected to the top conductive element 720 can extend through the second slot 716 in the insulating portion 704 and extend out the side of the shunt 700. The first sense lead 710 from the bottom conductive element 722 is Figure 8 , because the first sense lead 710 extends through the insulating portion 704 and extends out of the side of the shunt 700 at a different circumferential position on the shunt 700 relative to the second sense lead 712. In other words, in Figure 8 In the view shown in FIG. 7 , the first sense lead 710 is present in and leads out from a portion of the shunt 700 , which is hidden to illustrate the cross section.

[0063] Fig. 9 A rotated cross-sectional view of the shunt 700 is shown. In this view, the first sense lead 710 is led out to the side through an opening in the insulating portion 704 , where it is separated from the top conductive element 720 by a portion of the insulating portion 704 .

[0064] exist Fig.10In another embodiment shown in FIG. 1 , a shunt 900 includes a resistive portion 902 and an insulating portion 904, the resistive portion 902 being formed by a plurality of resistors 932 mounted on a flexible circuit 930. The resistive portion 902 may include an outer layer surrounding the insulating portion 904. According to this embodiment, conductive elements 920 and 922 may be placed 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, a clip 924 extends from the conductive element 920 in the direction of the conductive element 922, and a clip 926 extends from the conductive element 922 in the direction of the conductive element 920. Each clip 924 or 926 has a structure that allows a conductive element or cap to contact the flexible circuit 930 and provide a conductive path across the shunt 900 through the resistive portion 902. Furthermore, each conductive element 920 or 922 may have a structure that shares a central axis with the shunt 900 and may be rotated about the axis without the corresponding clip 924 or 926 losing contact with the flexible circuit 930 .

[0065] A first sense lead contact 910 may be provided that extends from the bottom conductive element 922 through the interior of the opening of the shunt 900 and extends out of the slot near the top of the shunt 900, as shown in the lower right view. In this embodiment, the sense leads may be built entirely into the flexible circuit. A second sense lead 912 may extend from the top conductive element 920, as shown in the upper right view. By rotating the shunt 900, the user may position the first sense lead 910 and the second sense lead 912 so that the measurement leads will experience minimal magnetic pickup from the magnetic field that surrounds and passes through the shunt 900.

[0066] Fig.11 and 12 Another embodiment of a flow splitter 1000 is illustrated. Fig.12 A ceramic insulating portion 1004 is shown which provides a structural substrate for the shunt 1000, but in Fig.11 1002 and has been removed to show the sense line leads and resistor. Conductive element 1020 is connected to the high side of resistive portion 1002 and has a sense lead portion 1012 as one of the contacts. Resistive portion 1002 in this embodiment includes a resistor that may have circuit 1030. Hexagonal conductive element 1006 is electrically connected to the low side of the resistor and has a second sense lead, such as 1008, that extends upward through an opening on the interior of shunt 100 and that comes out on either side of another sense lead 1012. Fig.12An assembly is shown with an insulating portion 1004 comprising a ceramic washer on which resides a resistor 1002 and circuitry 1030. The resistor and circuitry may be coated on the exterior of the ceramic washer body 1004. By rotating the shunt 1000, the user may position the sense leads so that they experience minimal magnetic pickup from the magnetic field surrounding through the shunt 1000.

[0067] In this manner, an embodiment provides a test and measurement accessory for measuring voltage in a current path between a bus bar and a module without contributing too much inductance to the measurement. The accessory includes a shunt having an opening through which one of the sense leads extends. The shunt allows a measurement of a voltage drop across the shunt to be converted to a current measurement while minimizing any additional path length that may affect the measurement.

[0068] Embodiments of the present disclosure generally include measuring current using a device including a combined shunt and Rogowski coil. The output of the combined shunt and Rogowski coil can be fed through a compensation pole (such as a passive RC or LR filter). Some embodiments can connect the output (one or more) of the current measuring device to an isolation probe. The embodiments involve inserting a shunt with a sense lead into a current path to be measured. The current measuring device includes a Rogowski coil at least partially wrapped around the shunt. The current measuring device is configured to combine the output signals from the shunt and the Rogowski coil. In some embodiments, the Rogowski coil is placed in series with the shunt sense lead.

[0069] This configuration produces the voltage:

[0070]

[0071] Among them, M R is the mutual inductance of the Rogowski coil and the current in the shunt. The coil is attached to the shunt sense lead as opposite the current return path as practical. This avoids the strongest magnetic field and thereby produces a canceling mutual inductance M that is approximately equal to L C . With M C Unlike L, M of a uniform Rogowski coil around a conductor R Does not change with skin depth induced shifts in the current path.

[0072] By making M c ≈L and M R >>LM c , the voltage can be approximated closely as:

[0073]

[0074] This represents a single-zero frequency response and can be flattened with a single-pole compensator such as an RC filter with the same time constant, i.e., R f C f =M R / R. At low frequencies, the R·i term dominates the shunt voltage, the compensation pole / RC filter is flat, and the shunt operates as a standard shunt. At high frequencies, M R The di / dt term dominates the shunt voltage, the compensation pole acts as an integrator for the Rogowski coil, and the final output voltage remains flat. The output voltage of the compensation pole can be measured by an isolated probe to maintain the isolation advantage of the Rogowski coil. The compensation pole can take many forms, including various architectures of RC (resistor capacitor) filters or LR (inductor resistor) filters.

[0075] Since DC and low frequencies are handled by the shunt action, the Rogowski coil inductance can be optimized for high frequency operation. This allows designs to have smaller coil inductance and higher frequency coverage than a stand-alone Rogowski coil.

[0076] Fig.13 A block diagram of a test and measurement system including a current measuring device in the form of a current shunt is shown. It should be noted that the figure shows several components that are not required for the current measuring device, but provides context for various embodiments of the device. Fig.13 1, a device under test (DUT) 1110 has a current measurement device 1112 attached to it. The current measurement device may include built-in or "welded" components, or attachable / detachable components. The DUT will typically be connected to a test and measurement instrument 1120 via one or more probes 1114. In some cases, one or more probes may include an "isolated probe," where the probe is galvanically isolated from the instrument. For higher voltage and frequency operations, including those with wide bandgap (WBG) devices, isolated probes allow for more accurate measurements and reduce shock hazards.

[0077] As will be discussed in more detail later, one or more filters at the instrumentation stage may receive the output of the measurement device 1112. These are different from the compensated pole filters discussed above. The filter 1116 may take the form of a discrete component, such as a digital signal processor or an analog filter, or may be generated by the processor 1118 executing instructions to apply filtering to the incoming signal.

[0078] The Rogowski coil may be implemented in a two layer (or more) flexible circuit board which may then be wrapped and soldered to a bus bar or surface mount metal alloy shunt 1130 such as Figures 14A-14DThe coil may be wound around the resistive portion 1132 or 1136 of the shunt 1130, which may typically be made of manganese copper. Fig.14A In an embodiment, a sense lead such as 1134 protrudes from the shunt bar. Figures 14B-14D Different embodiments of a resistor portion 1132 or 1136 in the middle of a copper portion are shown.

[0079] Fig.15 and 16 A current measuring device including a combined shunt with a sense lead and a Rogowski coil in various embodiments is shown. Fig.15 In the single-ended implementation shown in , a shielded reference, which may include an isolation probe or an isolation barrier, 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 is connected to the coil, R f The other end is connected to C f and the probe input, while C f The other end of the probe is connected to the probe reference.

[0080] A set of traces, represented by 1142, is formed on a layer of the flexible circuit closest to the shunt. Another set of traces, represented by 1144, is formed on the opposite side of the flexible circuit layer away from the shunt. In some embodiments, the flexible circuit may have an insulating layer or a flexible dielectric core between the layer with traces 1142 and the layer with traces 1144, and in some embodiments may also have insulating layers as the top and bottom layers of the flexible circuit. Trace 1142 is connected to trace 1144 through a via in the flexible circuit so that the traces and vias form a continuous conductive Rogowski coil structure in the flexible circuit. When the coil is wrapped around the shunt, this causes the magnetic field surrounding the shunt to flow between the two sets of traces. The portion of the trace marked Mc is placed as close to the shunt as possible and opposite the return current path to form a canceling mutual inductance. The Rogowski coil portion is then at least partially wrapped around the shunt. In one embodiment, a transmission line such as 1148 is connected to the coil. In another embodiment, the transmission line may be connected to the isolation barrier, and in yet another embodiment, the isolation barrier is present in the probe.The coil output may also be connected to a single-pole compensator 1146 with a fixed time constant. Fig.15 An embodiment comprising an RC filter having a filter resistor R f and filter capacitor C f .

[0081] Fig.16A differential signaling embodiment is shown. In a differential implementation, a shielded portion of the isolation barrier, such as the shield of an isolation probe, can be connected to either side of the shunt. One half of the Rogowski coil 1151 can be placed on each side of the shunt to feed the differential signal through the compensation pole 1156. This can be fed from one side of the differential probe input to the other side to the R on each side. f / 2 to C f Alternatively, C f Two capacitors 2 C from each signal line to the reference f In another embodiment, the differential transmission line can be periodically "twisted" to cancel out the pickup of stray electromagnetic fields.

[0082] Fig.17 An embodiment of a shunt with a Rogowski coil in a bus bar embodiment is shown, where the Rogowski coil is sandwiched within a folded bus bar shunt. The bus bar shunt 1170 has a resistive portion 1172. The shunt is folded in half to reduce 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 wrapped around the top to connect to one side of the shunt, and another sense lead is wrapped underneath (which is hidden in this view) to connect to the other side of the shunt. A square pin connector 1178 at the end of a portion of the flex wire 1176 connects it to an isolation barrier or probe. The traces on the flex wire of the coil and the compensation pole components are not shown.

[0083] Fig.18 An embodiment of a surface mount shunt is shown with a flex circuit 1180 underneath it between the shunt and the return path in the circuit board on which the shunt will be mounted. The shunt includes a metal portion 1182 and a resistive portion 1184. Each sense lead (such as 1183) is wrapped around the top of the shunt through a portion 1181 of the flex circuit 1180 and connected to each metal portion (such as 1182) on either side of the shunt. In this figure, the flex circuit traces that form the Rogowski coil are shown at 1186. Although not shown, those traces will continue up the flex circuit 1180 to the compensation pole component and square pin connector 1188.

[0084] There are many modifications and variations. For example, the filter resistor R f Can be used as a termination for the transmission line between the shunt / coil and the filter, allowing the probe 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 providing additional space for the probe, minimizing insertion inductance.

[0085] Since the Rogowski coil is directly connected to the shunt wound around it, it does not require high voltage insulation and can be placed very close to the shunt. This can further reduce the coil inductance by keeping the coil as short as possible.

[0086] If the return current path is well defined, such as for a surface mounted shunt on a return plane layer within a PCB, the Rogowski coil self-inductance can be further minimized by shortening the coil to cover only the space between the shunt and the return path, rather than completely surrounding the shunt. The magnetic field is strongest within the current loop, so this arrangement will achieve nearly as much mutual inductance as full enclosure, but with considerably lower self-inductance. This arrangement also avoids vias used to implement the coil in the flex circuit in the sharp bends around the sides of the shunt, reducing the likelihood of via cracking.

[0087] The compensation filter time constant can be combined with M by any combination of methods. R / R time constants. For example, in one embodiment, the shunt and Rogowski coil can be built together as a single unit with appropriate component values. As an example, this can take the form of Fig.17 or the form shown in 18.

[0088] Another embodiment provides for the selection of a fixed time constant filter suitable for a given shunt Rogowski coil pair. This can be done in Fig.15 and 16 In another embodiment, the filter block can provide one or more programmable filters, such as using FETs to switch C f The capacitor in the DAC. Due to the self-inductance of the Rogowski coil, the filter resistor R f The response pole caused by the load can be reduced by placing some f In another embodiment, the Rogowski loop area and / or pitch can be gradually reduced along the length of the coil so that the mutual inductance M R This can be adjusted by sliding the appropriate section of the progressively smaller coil under the shunt.

[0089] about Fig.13 The system shown in FIG. 1 can also use the acquired signal from the probe as it enters the instrument to adjust the time constant of the compensation pole and M R / R. For example, the filter 1116 applied after the signal is acquired by the probe can take the form of a DSP zero-pole filter applied to the acquired waveform to offset any remaining filter time constant mismatch. In addition, if the skin effect begins to significantly change the effective resistance R at the frequency, M RIf the di / dt term is not sufficient to dominate the R·I term, filter 1116 may include an analog and / or DSP filter applied to compensate for the resulting error in the crossover region between the shunt and Rogowski dominated responses.

[0090] Fig.19 An embodiment of a washer current shunt 1200 similar to those described above is shown. The embodiment here includes a Rogowski coil in a washer current shunt, where the coil surrounds a resistive portion. 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 measuring device in this embodiment has a resistive core with an opening 1214 from the top surface of the core to the opposite surface (from top to bottom as shown in the figure) through which a screw will be inserted. Although there are many different ways to provide a Rogowski coil, and other structures for including it in a washer current shunt, one possible embodiment is to manufacture the Rogowski as a printed circuit board (PCB).

[0091] Similarly, for the other embodiments of the Rogowski coil and shunt resistor discussed above, the signals from the Rogowski coil and the shunt resistor can be combined by the test and measurement equipment. The combination can include placing the coil in series with the shunt resistor, or combining them by adding the two signals together. The shunt resistor and the coil can be wired in parallel, and the combination of their signals applied by the test and measurement equipment.

[0092] Fig. 20 A more detailed view of one of the resistor core and conductive surface is shown. As shown here, the resistor core 1208 has a contact area on the end face of the core 1216. The other end face has the same contact area. An insulating layer surrounds the core, much like a coil structure, until the outside of the resistor core to allow the core to contact the conductive surface.

[0093] Fig.21 A more detailed view of the Rogowski coil 1206 is shown. In this view, electrical contacts such as 1218 can be seen. As will be shown in more detail below, these allow a connection in a series configuration between a resistive core on one contact and a measurement lead on another contact.

[0094] Fig. 22A more detailed view of the resistor core 1208 is shown. The resistor 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 measurement device will enter a mode in which the Rogowski coil becomes active. As discussed above, the shunt resistor is active from DC up to lower frequencies. As the frequency of the signal increases, the Rogowski coil becomes active. The choice of wall thickness determines the effective measurement bandwidth.

[0095] Fig.23 An assembled current measurement device is shown having conductive layers 1202 and 1210 in contact with a resistive core 1208. The 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 to allow for insertion of a screw or other fastener.

[0096] The contacts on the Rogowski coil can be electrically connected to the resistive core to place it in series in different ways. In a first embodiment, one of the electrical contacts on the coil structure is connected to one of the conductive layers through a sense lead 1220 . Fig.23 One example shown in uses the top conductive surface. Another electrical contact has a measurement lead 1222. Another measurement lead 1224 is electrically connected to another conductive surface of the structure.

[0097] Alternatively, the insulating layer may have a gap or slot. In one embodiment, the insulating layer has the shape of the letter "C". This allows the connection of the measurement lead 1226 to the Rogowski coil electrical contact directly from the top surface of the resistor core. The measurement lead 1222 will be the same, and the other measurement lead 1228 will directly contact the resistor core and lead out through the slot or gap in the lower insulating layer now shown.

[0098] In this manner, a washer current shunt having a shunt resistor and a Rogowski coil in a form factor that allows for insertion into a fastener may be provided.

[0099] In another embodiment, the coil is present in a flexible circuit substrate as discussed above, but in a multi-layer embodiment that may provide improved cancellation of magnetic fields. Fig.24 A flexible substrate 1230 having multiple layers is shown. A first layer 1232, shown in a set of single hash marks, has a first set of coil traces and contact points, such as 1238, which define a through hole between the layers. A second layer 1234 having a single hash mark in the opposite direction has a second set of coil traces and contact points for the other "end" of the through hole. The first and second coil traces are configured so that one set partially covers the other set in a first dimension. The coil structure is connected to a shunt resistor in any of the ways discussed above.

[0100] As can be seen in the upper right corner, when oriented here, the x direction or dimension spans the page from left to right or from right to left, the y direction or dimension extends from the top to the bottom or from the bottom to the top of the page, and the z direction or dimension enters and leaves the page. The view of the substrate is a top view looking down into the page. In the example here, this is the dimension in which the first and second coil traces overlap at least partially. The area where overlap occurs (such as 1236) is shaded with cross-hatching.

[0101] Two sets of coil traces form a Rogowski coil. A via (such as 1238) between the first layer and the second layer, a first series of coil traces and a first contact point, a second series of coil traces and a second contact point forming a Rogowski coil, and one of the first contact point and the second contact point are connected to a shunt resistor. Fig.24 In the embodiment of the present invention, the Rogowski coil has a single-ended output signal. The substrate is connected to the Rogowski coil as shown in the earlier embodiment discussed above and has similarly configured sense leads. Fig.24 In the embodiment of the present invention, the Rogowski coil has a single-ended output signal. The substrate is connected to the Rogowski coil as shown in the earlier embodiment discussed above, and has similarly configured sense leads.

[0102] Figure 24-28 The embodiment in has the advantage that there is no current loop region in the dimension perpendicular to the coil structure. This provides better cancellation and therefore more accurate measurements.

[0103] Fig.25 An embodiment of a third layer 1240 represented by a center trace is shown. The third layer provides mechanical stability to the structure. This prevents the coil structure from collapsing and keeps the other two layers in a substantially planar orientation. In addition, the trace on the third layer located at the center of the coil acts as a return current path. The center trace can be wider than the other traces to provide this mechanical stability.

[0104] Figure 26-28 An embodiment is shown in which the Rogowski coil has a differential output signal. When two coils overlap, the relationship between them can define the way in which the coils operate. In the figures, the coils are defined by through holes from top to bottom. Fig.26 In an embodiment of the invention, the through holes define an A coil and a B coil, wherein the coils have an ABAB pattern when looking down into 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 coils, which serve to locally cancel the magnetic field in the z direction.

[0105] exist Fig. 27In the example, the vias from top to bottom are associated with the coils 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 to locally cancel the magnetic field in the z-direction.

[0106] Fig.28 A coil configuration is shown where the coils again have an ABBA configuration, centered in the x-direction, but differ in the y-direction. While the winding traces around the outside of the coils serve to cancel the fields in the z-direction, each loop at one end of the coil in the y-direction has its complement at the other end. This cancels the fields across a greater distance than the local cancellation embodiment described above.

[0107] Fig.29 An embodiment of a coil structure 1250 implemented in a rigid substrate such as ceramic or glass is shown. This type of substrate may have the advantages of surface mount technology (SMT) and the ability to manufacture the coil structure at the wafer level using thin and thick film processes. They will then be cut to produce individual current measurement devices. Fig.29 A detailed view of the conductive structure without the substrate is shown.

[0108] The coil structure has metal traces (such as 1252) on a first surface of the rigid substrate. Vias (such as 1254) connect those traces with traces (such as 1256) on the bottom surface. This forms the coil structure. Contact pads (such as 1258 and 1260) allow connection to measurement leads. As will be discussed below, the shunt resistor will typically be mounted to the top surface. It should be noted that references to top and bottom are relative to the individual orientations shown in the figures. Although Fig.29 , but may include a center trace through the middle of the coil structure to provide a return path, similar to Fig.25 Of the 1240.

[0109] In one embodiment, discrete SMT resistors are laminated or otherwise mounted on top of the coil substrate by soldering, gluing to exposed pads, etc. In any embodiment, the resistors can be mounted above the center axis of the coil structure to provide a return path. Thin film resistor material or solder mask prevents the coil from shorting to the resistor. Fig.30 , resistor 1262 is shown in the upper portion of the image, and Rogowski coil structure 1250 and its substrate are shown in the lower portion of the image. Traces on the surface of the substrate forming part of the coil can be seen, as well as contact pads 1258 and 1260 and their counterparts providing Kelvin sensing.

[0110] Alternatively, the thin film process used to form the coil can be adapted to include a shunt resistor. Fig.31 As shown in , after forming the coil in the substrate, an insulating layer 1264 can be deposited on the coil structure. A resistive layer 1266 will then be deposited on the insulator to overlap to connect to the conductive surface. This process is very suitable for thin film and thick film processes at the wafer level.

[0111] Fig.32 Current and field diagrams of a current monitor including a shunt resistor and a Rogowski coil in a rigid substrate are shown. Arrows such as 1268 show current flow, with darker shading such as 1273 representing conductive material, including a coil structure 1274. Measurement contacts are shown at 1271 and 1272. Resist 1270 is located on insulator 1269. Magnetic field lines are shown by black dots such as 1276. Field lines represented by black dots can be located anywhere within the current loop specified by the arrows.

[0112] Fig.33 A method for making a Rogowski coil in a rigid substrate is shown. At 1280, the substrate undergoes masking and patterning with a through-hole pattern. Typically, the mask covers the portion of the substrate to be retained and the exposed portion to be removed, although the reverse is also possible. If the substrate is glass, the substrate is baked at 1282 to convert the exposed area into ceramic. If the substrate is ceramic, this step is not required. The portion of the substrate defined by the masking and patterning steps is then removed to form a through hole, such as 1274. Then a conductive material is deposited into the through hole, such as by electroplating at 1286. Then a thicker metal layer is deposited on both the top and bottom surfaces of the substrate at 1288. Then, it is masked, patterned and processed, for example by etching, at 1290 to form a coil trace connecting the through hole and the contact pad and other conductive portions. As discussed above, the shunt resistor is connected at 1292 by lamination and welding / pasting or by deposition of an insulator and a resistive layer.

[0113] Example

[0114] Illustrative examples of the disclosed technology are provided below. Embodiments of the technology may include one or more of the examples described below and any combination thereof.

[0115] Example 1 is a current measuring device comprising: a shunt resistor having a measuring lead, the shunt resistor including a resistor core having an opening, the shunt resistor being configured to be located in a current path of a current to be measured; a Rogowski coil surrounding the resistor core, the Rogowski coil having electrical contacts; a conductive layer on a first side of the resistor core, and a conductive layer on a second side of the resistor core opposite to the first side; and one or more insulating layers between each of the conductive layers and the Rogowski coil, the current measuring device being configured to combine signals from the shunt resistor and the Rogowski core.

[0116] Example 2 is the current measurement device of Example 1, wherein the current measurement device is configured to combine the signals by one of placing a Rogowski coil in series with the sense lead, or by adding the signals.

[0117] Example 3 is the current measuring device of Example 1 or 2, wherein the resistive core is electrically connected to one of the Rogowski coil electrical contacts, and another of the Rogowski coil electrical contacts is electrically connected to a first one of the measurement leads.

[0118] Example 4 is the current measurement device of Example 3, wherein the resistive core is electrically connected to one of the Rogowski coil electrical contacts through a conductive layer on the first side of the resistive core.

[0119] Example 5 is the current measurement device of Example 3, wherein the resistive core is electrically connected directly to one of the Rogowski coil electrical contacts through a gap in one or more insulating layers.

[0120] Example 6 is the current measurement device of any one of Examples 1 to 5, wherein one of the measurement leads is one of: electrically connected to the resistor core through a conductive layer on the second side of the resistor core, or directly electrically connected to the resistor core through a gap in one or more insulating layers.

[0121] Example 7 is the current measurement device of any of Examples 1 to 6, wherein the resistive core has a wall thickness selected to set a frequency at which the Rogowski coil becomes active.

[0122] Example 8 is the current measurement device of any of Examples 1 to 7, wherein the Rogowski coil comprises a coil in a printed circuit board.

[0123] Example 9 is a current measuring device comprising: a shunt resistor having a sensing lead, the shunt being configured to be located in a current path of a current to be measured; and a Rogowski coil on a flexible substrate at least partially wrapped around the shunt, the current measuring device being configured to combine signals from the shunt resistor and the Rogowski coil.

[0124] Example 10 is the current measurement apparatus of Example 9, wherein the Rogowski coil is configured such that no loop region exists in a dimension perpendicular to the Rogowski coil.

[0125] Example 11 is a current measuring device of any one of Examples 9 or 10, wherein the Rogowski coil includes: a first layer of flexible substrate, which includes a first series of coil traces and a first contact point; a second layer of flexible substrate, which includes a second series of coil traces and a second contact point, the second series of coil traces and the second contact point at least partially covering the first series of coil traces and the first contact point in the z direction; and a through hole between the first layer and the second layer, the first series of coil traces and the first contact point and the second series of coil traces and the second contact point forming the Rogowski coil, and one of the first contact point and the second contact point is connected to a shunt resistor.

[0126] Example 12 is the current measuring device of Example 12, further comprising a third layer between the first layer and the second layer.

[0127] Example 13 is the current measurement device of Example 12, wherein the third layer includes a trace located at the center of the Rogowski coil to serve as a return path.

[0128] 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.

[0129] 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.

[0130] Example 16 is the current measurement device of any of Examples 9 to 15, wherein the current measurement device is configured to generate a differential output signal.

[0131] Example 17 is the current measurement device of Example 16, wherein the first series of coil traces overlap the second series of coil traces so that the first contact points and the second contact points form an alternating ABAB pattern in the y-direction dimension to locally cancel the field in the first dimension.

[0132] Example 18 is the current measurement device of Example 16, wherein the first series of coil traces overlap the second series of coil traces so that the first contact point and the second contact point form an ABBA pattern centered in the x direction and varying in the y direction to locally cancel the field in the first dimension.

[0133] Example 19 is a current measuring device of Example 16, wherein the first series of coil traces overlap the second series of coil traces so that the first contact point and the second contact point form an ABBA pattern centered in the x direction and having opposite loops at the ends in the y direction to cancel the field at a greater distance than the local cancellation coil.

[0134] Example 20 is a current measuring device comprising: a rigid substrate having a top surface and a bottom surface; a through hole passing through the rigid substrate from the top surface to the bottom surface, the through hole being filled with a conductive material; a conductive layer connected to the through hole on the top surface and the bottom surface to form a Rogowski coil structure; one or more insulating layers directly on the coil structure; a shunt resistor directly on the one or more insulating layers; and a measurement contact on the bottom surface.

[0135] Example 21 is the current measuring device of Example 20, wherein the rigid substrate is one of glass or ceramic.

[0136] Example 22 is a current measuring device of any of Examples 20 or 21, wherein at least one of the one or more insulating layers is present on a top surface of a rigid substrate, the top surface having exposed contact pads electrically connected to the coil structure, and a shunt resistor is present on the insulating layer on the top surface of the rigid substrate and is electrically connected to the exposed pads.

[0137] Example 23 is the current measurement device of any of Examples 20 to 22, wherein the shunt resistor is centered over a central axis of the coil structure.

[0138] Example 24 is the current measurement device of any of Examples 20 to 23, wherein the device further comprises a conductive trace passing through the middle of the coil structure to provide a return path.

[0139] Example 25 is a current measuring device of any one of Examples 20 to 24, 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 includes a resistive material layer located on the at least one insulating layer and in contact with a conductive layer on the top surface.

[0140] Example 26 is a method for manufacturing a current measuring device, comprising: masking a rigid substrate with a through-hole pattern; removing a portion of the substrate to form a hole through the substrate; depositing a conductive material to form a conductive through-hole in the hole; and depositing a second layer of conductive material on the top and bottom surfaces of the substrate to connect the through-holes to form a coil pattern and a measurement contact on one surface of the rigid substrate; masking and patterning the second layer of conductive material on the top and bottom surfaces to connect the through-holes to form a Rogowski coil structure and a contact pad on the top surface; and connecting a shunt resistor to the Rogowski coil structure.

[0141] Example 27 is the method of manufacturing of Example 26, wherein the rigid substrate comprises glass, and masking the rigid substrate with the via pattern comprises baking the rigid substrate to convert the exposed areas to ceramic prior to removing portions of the substrate.

[0142] Example 28 is the method of manufacturing any of Examples 26 or 27, wherein connecting the shunt resistor includes attaching a surface mount resistor to the contact pad.

[0143] Example 29 is the method of making any of Examples 26 to 28, wherein connecting the shunt resistor includes depositing one or more insulating layers on the coil structure and depositing a resistive material on the one or more insulating layers.

[0144] Example 30 is the method of manufacturing 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.

[0145] Example 31 is a method of manufacturing of Examples 26 to 30, wherein a plurality of current measuring devices are manufactured at a wafer level and then cut to produce individual current measuring devices.

[0146] Although particular aspects of the present disclosure have been illustrated and described for purposes of illustration, it will be appreciated that various modifications may 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.

[0147] In addition, this written description refers to specific features. It is to be understood that the disclosure in this specification includes all possible combinations of those specific features. For example, where a specific feature is disclosed in the context of a particular aspect, the feature may also be used in the context of other aspects to the extent possible.

[0148] Furthermore, when reference is made in the present application to a method having two or more defined steps or operations, the defined steps or operations may be performed in any order or simultaneously, unless the context excludes those possibilities.

[0149] All features disclosed in this specification (including claims, abstract and drawings) and all steps in any disclosed method or process may be combined in any combination, unless at least some of the combinations of such features and / or steps are mutually exclusive. Unless otherwise expressly stated, each feature disclosed in the specification (including claims, abstract and drawings) may be replaced by an alternative feature for the same, equivalent or similar purpose.

[0150] Although specific examples of the present invention have been illustrated and described for purposes of illustration, it will be appreciated that various modifications may be made without departing from the spirit and scope of the present invention.Accordingly, the present invention should not be limited, except as by the appended claims.

Claims

1. A current measuring device, comprising: a shunt resistor having a measurement lead, the shunt resistor including a resistive core having an opening, the shunt resistor being configured to be located in a current path of a current to be measured; a Rogowski coil surrounding a resistive core, the Rogowski coil having electrical contacts; a conductive layer on a first side of the resistive core, and a conductive layer on a second side of the resistive core opposite the first side; as well as Between each of the conductive layers and the one or more insulating layers of the Rogowski coil, a current measurement device is configured to combine signals from the shunt resistor and the Rogowski core.

2. The current measurement device of claim 1, wherein the current measurement device is configured to combine the signals by one of: placing a Rogowski coil in series with the sense lead, or by adding the signals.

3. The current measuring device of claim 1, wherein the resistor core is electrically connected to one of the Rogowski coil electrical contacts, and the other of the Rogowski coil electrical contacts is electrically connected to a first of the measuring leads.

4. The current measuring apparatus of claim 3, wherein the resistive core is electrically connected to one of the Rogowski coil electrical contacts through a conductive layer on a first side of the resistive core.

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

6. The current measurement device of claim 1, wherein one of the measurement leads is one of: electrically connected to the resistive core through a conductive layer on the second side of the resistive core, or directly electrically connected to the resistive core through a gap in one or more insulating layers.

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

8. The current measuring apparatus of claim 1, wherein the Rogowski coil comprises a coil in a printed circuit board.

9. A current measuring device, comprising: a shunt resistor having a sense lead, the shunt being configured to be located in a current path of a current to be measured; as well as A Rogowski coil is at least partially wrapped on a flexible substrate around the shunt resistor, the current measurement device being configured to combine signals from the shunt resistor and the Rogowski coil.

10. The current measuring apparatus according to claim 9, wherein the Rogowski coil is configured such that no loop region exists in a dimension perpendicular to the Rogowski coil.

11. The current measuring device according to claim 9, wherein the Rogowski coil comprises: a first flexible substrate including a first series of coil traces and first contact points; a second layer of flexible substrate comprising a second series of coil traces and second contact points, the second series of coil traces and second contact points at least partially covering the first series of coil traces and first contact points in the z-direction; as well as A via between the first layer and the second layer, the first series of coil traces and the first contact point and the second series of coil traces and the second contact point form a Rogowski coil, and one of the first contact point and the second contact point is connected to a shunt resistor.

12. The current measuring device of claim 11, further comprising a third layer between the first layer and the second layer.

13. The current measurement apparatus of claim 12, wherein the third layer includes a trace located at the center of the Rogowski coil to serve as a return path.

14. The current measurement device of claim 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.

15. The current measurement device of claim 9, wherein the current measurement device is configured to generate a single-ended output signal.

16. The current measurement device of claim 9, wherein the current measurement device is configured to generate a differential output signal.

17. The current measurement apparatus of claim 16, wherein the first series of coil traces overlay the second series of coil traces such that the first and second contact points form an alternating ABAB pattern in the y-direction to locally cancel the field in the first dimension.

18. The current measurement apparatus of claim 16, wherein the first series of coil traces overlay the second series of coil traces such that the first and second contact points form an ABBA pattern centered in the x-direction and varying in the y-direction to locally cancel the field in the first dimension.

19. The current measuring device according to claim 16, wherein: The first series of coil traces overlay the second series of coil traces so that the first and second contact points form an ABBA pattern centered in the x-direction and having opposing loops at the ends in the y-direction to cancel fields at a greater distance than a local cancellation coil.

20. A current measuring device comprising: a rigid substrate having a top surface and a bottom surface; a through hole passing through the rigid substrate from the top surface to the bottom surface, the through hole being filled with a conductive material; a conductive layer connected to the vias on the top and bottom surfaces to form a Rogowski coil structure; one or more insulating layers directly on the coil structure; Shunt resistors directly on one or more insulating layers; as well as Measuring contacts on the bottom surface.

21. The current measuring apparatus of claim 20, wherein the rigid substrate is one of glass or ceramic.

22. The current measuring device of claim 20, wherein at least one of the one or more insulating layers is present on a top surface of a rigid substrate, the top surface having exposed contact pads electrically connected to the coil structure, and a shunt resistor is present on the insulating layer on the top surface of the rigid substrate and is electrically connected to the exposed pads.

23. The current measurement apparatus of claim 20, wherein the shunt resistor is centered over a central axis of the coil structure.

24. The current measuring device of claim 20, wherein the device further comprises a conductive trace passing through the middle of the coil structure to provide a return path.

25. The current measurement device of claim 20, 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 comprises a layer of resistive material on the at least one insulating layer and in contact with the conductive layer on the top surface.

26. A method of manufacturing a current measuring device, comprising: masking the rigid substrate with a through-hole pattern; removing portions of the substrate to form a hole through the substrate; depositing a conductive material to form a conductive via in the hole; depositing a second layer of conductive material on the top and bottom surfaces of the substrate to connect the vias to form a coil pattern and measurement contacts on one surface of the rigid substrate; masking and patterning a second layer of conductive material on the top and bottom surfaces to connect the vias to form a Rogowski coil structure and contact pads on the top surface; and Connect a shunt resistor to the Rogowski coil structure.

27. The method of manufacturing of claim 26, wherein the rigid substrate comprises glass, and masking the rigid substrate with the via pattern comprises baking the rigid substrate to convert the exposed areas to ceramic prior to removing portions of the substrate.

28. The method of manufacturing as recited in claim 26, wherein connecting the shunt resistor comprises attaching a surface mount resistor to the contact pads.

29. The method of manufacturing as recited in claim 26, wherein connecting the shunt resistor comprises depositing one or more insulating layers on the coil structure and depositing a resistive material on the one or more insulating layers.

30. The method of manufacturing as recited in claim 26, further comprising passivating the second layer of conductive material on the top and bottom surfaces prior to attaching the shunt resistor.

31. The method of manufacturing as claimed in claim 26, wherein a plurality of current measuring devices are manufactured at a wafer level and then diced to produce individual current measuring devices.

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