CN119375529A - Current monitor incorporating shunt resistor with rogowski coil - Google Patents

Abstract

A current monitor incorporating a shunt resistor with a rogowski coil. A current measurement device having a shunt resistor with an opening and a resistive core with a measurement lead, a rogowski coil with electrical contacts surrounding the resistive core, conductive layers on first and second sides of the resistive core, one or more insulating layers between the conductive layers 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 the flexible substrate, the rogowski coil being at least partially wound around the shunt resistor. The current measurement device has a rigid substrate, a via filled with a conductive material through the rigid substrate, conductive layers connected to the via to form top and bottom surfaces 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

Current monitor incorporating shunt resistor with rogowski coil

Cross Reference to Related Applications

The present disclosure continues in section 18/198,800 of U.S. non-provisional patent application Ser. No. 18/198,800 entitled "SHUNT FORUSE IN BUSBAR-TO-MODULE CONNECTIONS" filed 5/17/2023, which claims the benefits of U.S. provisional application Ser. No. 63/400,831 entitled "LOW INSERTION INDUCTANCE HIGH-POWER BUSBAR CURRENT SHUNT" filed 8/25/2022 and U.S. provisional application Ser. No. 63/344,981 entitled "COAXIAL SHUNT FOR USE IN BUSBAR-TO-MODULE CONNECTIONS" filed 23/5/2022. The present disclosure also continues in section 18/225,034 of U.S. non-provisional application No. 18/225,034 entitled "CURRENT MONITOR COMBINING A SHUNT RESISTOR WITH A ROGOWSKI COIL" filed on day 21 of 7 in 2023, which claims the benefit of U.S. provisional application No. 63/392,471 entitled "CURRENT MONITOR COMBINING A SHUNT RESISTOR WITH A ROGOWSKI COIL" filed on day 26 of 7 in 2022. The present disclosure also claims the benefit of U.S. provisional application No. 63/515,570 entitled "WASHER SHUNT WITH A ROGOWSKI COIL FOR MEASURING CURRENT IN A DEVICE UNDER TEST" filed on 25 th 2023, U.S. provisional application No. 63/516,093 entitled "CURRENT MONITOR COMBINING A SHUNT RESISTOR WITH A ROGOWSKI COIL USING THIN FILM PROCESS" filed on 27 th 2023, and U.S. provisional application No. 63/580,970 entitled "FLEX CIRCUIT INCLUDING A ROGOWSKI COIL" filed on 6 th 2023 9. The disclosures of all of the above-referenced applications are incorporated herein by reference in their entirety.

Technical Field

The present disclosure relates to test and measurement systems, and more particularly to an apparatus and method for measuring or monitoring current.

Background

High-power switching devices are usually constructed in a module form, which has screw terminals for connection to bus bars (bus bars) of high-current terminals. To support rapid current changes in switching transients (SWITCHING TRANSIENTS), capacitor banks are typically mounted on the bus bars and are typically close to the module to minimize series inductance. This then results in difficulties in inserting a current measurement device between the capacitor bank and the module to measure switching transients, as it may insert so much inductance as to alter the measured transients.

Various approaches have addressed this problem, but all have their own drawbacks. For example, one solution employs rogowski coils around the bus bars. Rogowski coils lack DC capability, have limited bandwidth, and may have accuracy problems depending on the location of the coil. Similarly, another solution uses a current transformer around the extension pole between the bus bar and the module. However, current transformers may increase inductance in addition to lacking DC capability and typically have limited bandwidth.

Another approach is to insert a coaxial shunt into the gap in the bus bar. Typically, these coaxial shunts have three concentric conductors in the shape of a cylinder, a return path on the outside, a resistive shunt material in the middle, and a sense lead extending through the innermost portion of the coaxial shunt. Such coaxial shunts constrain the magnetic field between the outer and intermediate materials to cancel any inductance affecting the sense leads, and they allow for DC coupling and wide measurement bandwidth. These shunts may be difficult to insert into the gap in the bus bar and may lengthen the electrical path such that unwanted inductance is inserted in the current path.

Such as large and rapidly varying currents common in switching power supplies and motor drives using wide bandgap semiconductors (and in lightning or other arcing), are well known to be difficult to measure accurately.

One method commonly used 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 approach works well for DC and lower frequencies, but is affected at higher frequencies by the inductive voltage drop (inductive drop) across the shunt, which exceeds the resistive voltage drop for frequencies above frequency f _c:

When measuring large currents, a relatively small shunt resistance R is required to keep the voltage drop and power consumption of the shunt within reasonable limits, which results in an unfavorably low available bandwidth f _c (objectionably).

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 leads exit the shunt within the resistive cylinder. The symmetrical nature and the 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 create an inductive voltage drop to the measured voltage inside the shunt. The coaxial shunt eliminates the measured inductance (inductance contained in the measured voltage drop), but requires a longer current path through the shunt, thereby increasing the inserted inductance (inductance inserted into the current path of the system under test). Even without measuring inductance, coaxial shunts have limited bandwidth due to the skin effect of the shunt material. As the 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, creating a smaller resistive voltage drop on the inside where the voltage is measured.

Another method for increasing the available bandwidth of a shunt is to add a cancellation mutual inductance M _c in the lead dressing (dress) of the voltage measurement lead of a conventional shunt:

This minimizes the insertion inductance by not requiring a specific return current path, but is more cumbersome to implement, as the return current path must still be known to determine the lead placement to achieve cancellation (M _C =l). The cancellation method is also affected at high frequencies due to the skin effect, in that as the skin depth approaches the shunt thickness, the current path through the shunt will shift in physical position, changing M _C, L, and R.

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 the magnetic field and the voltage induced on 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 current. In fact, there is a tradeoff between the low frequency availability range and the high frequency bandwidth of rogowski coils. 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 driving the load impedance of the integrator.

The disclosed technology arrangement addresses the shortcomings of the prior art.

Drawings

Fig. 1A shows a screw terminal of a switchgear module.

Fig. 1B shows an additional example of a screw terminal of a switchgear module.

Fig. 2 shows an example of a conventional coaxial splitter.

Fig. 3 shows a cross-sectional view of a busbar and module connection with an embodiment as an interposed shunt.

Fig. 4 shows a top view of the bus bar and module connection of fig. 3.

Fig. 5 shows a cross-sectional view of a component of the shunt of fig. 3.

Fig. 6 shows a cross-sectional view of another embodiment of a shunt.

Fig. 7 shows an embodiment of a shunt.

Fig. 8 and 9 illustrate alternative embodiments of the shunt.

Fig. 10 shows a view and an embodiment of a shunt.

Fig. 11 shows a view of the components of an embodiment of the shunt.

Fig. 12 shows a view of the shunt of fig. 11.

FIG. 13 shows a block diagram of a current measurement accessory within the test and measurement system.

Fig. 14A-14D illustrate different embodiments of current splitters.

Fig. 15 shows an embodiment of a current shunt in combination with a rogowski coil.

Fig. 16 shows an alternative embodiment of a current shunt in combination with a rogowski coil.

Fig. 17 shows an embodiment of a current shunt for installation in a bus bar in combination with a rogowski coil.

Fig. 18 shows an embodiment of a current shunt in combination with a rogowski coil for surface mounting on a printed circuit board.

Fig. 19 shows an exploded view of an embodiment of a washer current shunt in combination with a rogowski coil.

Fig. 20 shows the resistive portion and contact plate of an embodiment of a washer current shunt in combination with a rogowski coil.

Fig. 21 shows an embodiment of a rogowski coil.

Fig. 22 shows an embodiment of the resistive portion of an embodiment of a washer current shunt.

Fig. 23 shows an embodiment of an assembled rogowski coil with an embodiment of a measurement lead.

Fig. 24-25 illustrate single ended embodiments of rogowski coils on a flexible substrate.

Fig. 26-28 illustrate different embodiments of rogowski coils on a flexible substrate.

Fig. 29 shows an embodiment of a rogowski coil for a rigid substrate.

Figures 30-31 illustrate surface mount embodiments of rogowski coils in a rigid substrate.

Fig. 32 shows a current and magnetic field diagram of an embodiment of a current monitor in a rigid substrate.

Fig. 33 shows a process flow for manufacturing a rogowski coil in a rigid substrate.

Detailed Description

Embodiments herein relate to a test and measurement accessory device including a shunt configured to be interposed between a bus bar and a module. The accessory device enables measurement of the voltage drop across the shunt and, therefore, the current flowing between the bus bar and the module using the known resistance of the device. Some embodiments of the shunt are configured as a gasket 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 the electrical path length, and thus the inductance inserted into the current path, while maintaining the advantages of the DC capability and wide measurement bandwidth of conventional shunt resistors.

Fig. 1A and 1B show a module for a high-power switching device, which module has screw terminals 100 for connecting the module to a bus bar (not shown in fig. 1A and 1B). Screw terminal 100 includes a bolt 110 for mechanically attaching a bus bar to screw terminal 100 and for providing a current path between the module and the bus bar. To support rapid current changes in switching transients, a capacitor bank may be mounted on the bus bar and mounted close to the module to minimize series inductance. However, this may lead to difficulties in inserting a current measurement device between the capacitor bank and the module to measure switching transients, as it may insert so much inductance as to change the measured transients.

Fig. 2 shows a cross-section of an example of a conventional coaxial shunt 200 for measuring voltage drop across the shunt. The flow splitter comprises 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. A problem that arises with this type of structure is the current path. Current flows through the current pin 206 along the line shown at 214 and along the outer cylinder 202. This relatively long current path increases the overall electrical path length of the circuit or device being measured. This inserts an inductance into the path, which may change the measured transient. As discussed below, embodiments herein minimize any length added to the current path.

Fig. 3 shows a test and measurement accessory that includes a shunt 300 to be inserted between a bus bar 310 and a screw terminal 320 of an electronic module (such as the module shown in fig. 1A and 1B). Screw terminal 320 may be an example of screw terminal 100 shown in fig. 1A and 1B, or similar to screw terminal 100 shown in fig. 1A and 1B, but is shown as elongated in fig. 3 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. The embodiment of the flow splitter 300 is shaped such that it resembles a gasket. The shunt 300 having its washer-like shape includes a resistive portion 302 and may also include an insulating portion 304 in some embodiments.

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 may provide a current path 330 between the screw terminal 320 and the bus bar 310, and 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. The bolt 110 may then be inserted through the bus bar 310 and through the opening 306 of the shunt 300 and tightened into the screw portion 322 of the screw terminal 320. This secures the shunt 300 between the bus bar 310 and the screw terminal 320 and provides good electrical contact between these components.

The bolt 110 may be used as one contact 340 of the shunt to allow sensing of the voltage at the "bottom" end of the shunt 300, with the end of the shunt 300 contacting the screw terminal 320. The second contact may be located on bus bar 310, for example, at location 360, or directly connected to bus bar 310 to sense the voltage at the "top" end of shunt 300, with the end of shunt 300 contacting bus bar 310. The resistive portion 302 causes a voltage drop across the shunt 300, which may be measured at the first and second contacts. The measured voltage drop, along with a known resistance value of the shunt, may be used to determine the current flowing through the shunt, and thus the current flowing between the bus bar 310 and the screw terminal 320 of the module.

The bolt 110 extends through the shunt opening 306 to conveniently act as a sense lead and provide a contact 340 at the same "top" face of the assembled accessory device as a second contact 360. The contact 340 and the bolt 110 are electrically insulated from the resistive portion 302 of the shunt. In some embodiments, the insulating portion 304 of the shunt 300 electrically insulates the contact 340 from the resistive portion 302. In some embodiments, the 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 an 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.

Fig. 4 shows a top view of the assembly of fig. 3, with bus bars 310 mechanically fastened to screw terminals 320 of the electronic module and a shunt 300 interposed therebetween. As discussed, embodiments of the present disclosure may utilize the bolt 110 as one sense lead of the shunt 300 and the bus bar 310 as another sense lead, providing a contact surface for taking measurements, such as by connecting wires, leads of a test probe, or other measurement leads of a test and measurement instrument. The contacts allow for measurement of the voltage drop across the shunt, which can then be converted to 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 circulate through the bolt 110. Thus, the specific location of two or more contacts for the measurement leads on the contact surfaces of the bolt 110 and the bus bar 310 may change the measurement due to the magnetic field that surrounds the bolt 110.

For example, as illustrated in fig. 4, the measurement leads contacting the bolt 110 and the bus bar 310 at the first location 410 (denoted a 'and B') and the second location 420 (denoted a "and B") may enclose some loop area that is sensitive to magnetic flux. The locations marked with the changes in a are present on the bolts and the changes in B are present on the bus bar 310. Because the polarity of the magnetic pick-up will change between measurement locations, the third measurement location 430, denoted a and B, can be used as an intermediate location in the measurement lead where minimal magnetic pick-up is experienced. The specific location of this third measurement location 430 may depend on factors such as the thickness of the shunt 300 (shown as a dashed line because it is below the top of the bolt and bus bar 310) and the particular current path in the screw terminal 320 of the bus bar 310 of the electronic module.

In general, however, embodiments will have first and second contacts 340, 360 of sufficient size to allow some intermediate positions for placement of the measurement leads that reduce 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 error in high power switching devices.

Furthermore, in the embodiment of the shunt 300 shown in fig. 3, an insulating shoulder washer 350 may be included. The insulating shoulder washer 350 may be present 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. As shown in fig. 5, the insulating shoulder gasket 350 may also include conductive portions 356 and 358 to contact the bus bar 310 and the bolt 110 from fig. 3. Conductive portions 356 and 358 may include pins 352 and 354, pins 352 and 354 being represented by a and B in fig. 5. Pins 352, 354 may provide connection locations for measuring the voltage between points a and B, including the voltage drop across shunt 300 and the voltage drop due to the contact resistance of shunt 300 with upper bus bar 310 and lower screw terminal 320. Pins 352, 354, along with conductive portions 356, 358 and bus bar 310 and bolt 110, form at least two contacts for measuring voltage drops across the assembled components. As with the measurement position described with respect to fig. 4, prior to fully tightening bolt 110 to screw terminal 320, a user may rotate shoulder washer 350 to adjust the specific positions of pins 352 and 354 to minimize magnetic flux pick-up. In both examples of fig. 4 and 5, the optimal rotational position can be found experimentally by minimizing the high frequency content in the measured voltage. The magnetic pick-up (proportional to di/dt) is always orthogonal to the resistance drop, irrespective of the polarity, and therefore only artificially increases the high frequency content. Thus, the minimum high frequency content as a function of rotation is consistent with zero magnetic pickup.

Fig. 6 shows another example of a shunt 600. Shunt 600 is similar to shunt 300, including resistive portion 602 and insulating portion 604, but includes a kelvin sensing configuration with sensing leads 610 on shunt 600 itself. The sense leads 610 are present on an interior portion of the shunt 600 that extend parallel to the central axis of the shunt 600, e.g., through the insulating portion 604. In this way, having the sense leads 610 on the shunt 600 itself may avoid measuring voltage drops across the shunt 600 and the contact resistance between the bus bar and the module shown in fig. 3. Furthermore, extending the sense leads 610 through the interior portion of the shunt 600 may minimize magnetic flux pickup.

Embodiments of the shunt herein each have an opening through which one of the sense leads will extend. Although this is similar to the current example of the shunt given above, the sense leads herein are configured as part of the current path such that the length added to the current path is minimized compared to the length of the current path shown in fig. 3.

Fig. 7 illustrates an embodiment of a shunt 700. In this embodiment, the shunt 700 may still include a resistive portion 702 and an insulating portion 704. The insulating portion 704 may comprise a ceramic washer, and the resistive portion 702 may comprise a resistive material on a surface of the ceramic washer (e.g., coated (painted) on an inner surface of the ceramic washer as shown). One example material for the ceramic washer may be CoorsTek YZTP zirconia, but many other materials may 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 the top surface of the ceramic washer forming the insulating portion 704 and the second conductive element 722 is placed on the bottom surface. 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 by, for example, solder or braze. Furthermore, instead of the bolt, not shown in fig. 7, being used as a screw terminal for the sense leads, the first sense lead 710 provides one contact for the measurement leads and extends from the conductive element 722 on the bottom surface closest to the electronics module of fig. 1A and 1B to the top of the shunt 700 closest to the bus bar (shown in fig. 3). The conductive material forming the sense lead contact 710 may extend vertically parallel to the central axis of the shunt 700, but is insulated from the coated circuitry forming the resistive portion 702. In this way, the first sense lead extends through an opening in the interior portion of the shunt 700. Although the sense leads 710 are illustrated in an exaggerated height in fig. 7, the sense leads 710 generally extend vertically through the thickness or height of the ceramic washer.

The second sense lead 712 provides another contact 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 receiving the first and second sense leads 710 and 712, respectively. As illustrated, 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 that prevents the sense lead 710 from contacting the top conductive element 720. By rotating the shunt 700, the user can position the first and second sense leads 710, 712 such that they experience minimal magnetic pickup from the magnetic field circulating through the shunt 700.

The embodiment of fig. 7 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 washer 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 configurations described above, and may protect the shunt 700 from mechanical attachment compression forces, such as the screw forces of a screw terminal. Finally, the embodiment of fig. 7 may include at least one electrically conductive lock washer 740. Although fig. 7 illustrates a single lock washer 740 placed at the top of the shunt 700, embodiments may have lock washers at the top or bottom or both the top and bottom. The lock washer(s) may replace one or more of the compressible conductive washers.

Fig. 8 illustrates a cross-sectional view of another embodiment of a shunt 700. As shown, embodiments of the shunt 700 may be assembled with optional compressible conductive gaskets 730 and 732 on both the top and bottom surfaces of the shunt 700 to protect the insulating portion 704 from compressive forces. Further, in an embodiment, the second sense lead 712 connected to the top conductive member 720 may extend through the second slot 716 in the insulating portion 704 and out the side of the shunt 700. The first sense lead 710 from the bottom conductive element 722 is not visible in the illustrated cross-section of fig. 8 because the first sense lead 710 extends through the insulating portion 704 and out the sides of the shunt 700 at different circumferential locations on the shunt 700 relative to the second sense lead 712. In other words, in the view shown in fig. 8, the first sense lead 710 is present in and exits from a portion of the shunt 700 that is hidden from view in cross-section.

Fig. 9 shows a rotational cross-sectional view of the flow splitter 700. In this view, the first sense lead 710 exits to the side through an opening in the insulating portion 704, which is separated from the top conductive element 720 by a portion of the insulating portion 704.

In another embodiment shown in fig. 10, a shunt 900 includes a resistive portion 902 and an insulating portion 904, the resistive portion 902 being formed from 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 shunt 900. Each conductive element may contact the insulating portion 904 for mechanical support and one or more clips may be used to contact the resistive portion 902. For example, clip 924 extends from conductive element 920 in the direction of opposing conductive element 922, and clip 926 extends from conductive element 922 in the direction of conductive element 920. Each clip 924 or 926 has a structure that allows the conductive element or cap to contact the flexible circuit 930 and provide a conductive path across the shunt 900 through the resistive portion 902. Further, each conductive element 920 or 922 may have a structure that shares a central axis with the shunt 900 and may rotate about that axis without the respective clip 924 or 926 losing contact with the flexible circuit 930.

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 out of the slot near the top of the shunt 900, as shown in the bottom right view. In this embodiment, the sense leads may be fully built into the flex circuit. The second sense lead 912 may extend from the top conductive element 920, as shown in the top right view. By rotating the shunt 900, the user can position the first and second sense leads 910, 912 such that the measurement leads will experience minimal magnetic pickup from the magnetic field circulating through the shunt 900.

Fig. 11 and 12 illustrate another embodiment of a shunt 1000. Fig. 12 shows a ceramic insulating portion 1004 that provides a structural substrate for the shunt 1000, but has been removed in fig. 11 to show the sense line leads and resistors. Conductive element 1020 is connected to the high side of resistive portion 1002 and has sense lead portion 1012 as one of the contacts. The resistive portion 1002 in this embodiment includes a resistor that may have a circuit 1030. The 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 the shunt 100 and that exits on either side of another sense lead 1012. Fig. 12 shows an assembly with an insulating portion 1004, the insulating portion 1004 comprising a ceramic washer on which the resistor 1002 and the circuit 1030 are present. The resistor and circuitry may be coated on the exterior of the ceramic washer body 1004. By rotating the shunt 1000, the user can position the sense leads such that they experience minimal magnetic pickup from the magnetic field circulating through the shunt 1000.

In this way, embodiments provide a test and measurement accessory for measuring the voltage in the current path between the bus bar and the 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 the measurement of the voltage drop across the shunt to be converted to a current measurement while minimizing any additional path length that may affect the measurement.

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 may be fed through a compensation pole, such as a passive RC or LR filter. Some embodiments may connect the output(s) of the current measurement device to the isolation probe. The embodiments relate to inserting a shunt with a sense lead into a current path to be measured. The current measuring device comprises a rogowski coil at least partially wound around the shunt. The current measurement 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.

This configuration generates a voltage:

Wherein M _R is the mutual inductance of the rogowski coil with the current in the shunt. The coil is attached to the shunt sense lead as practically as possible opposite the current return path. This avoids the strongest magnetic field and thereby produces a cancellation mutual inductance M _C that is approximately equal to L. Unlike M _C and L, M _R of a uniform rogowski coil around a conductor does not change with skin depth induced offset in the current path.

By letting M _c be L and M _R>>L-M_c, the voltage can be approximated closely as:

This represents a single zero frequency response and may be flattened with a single pole compensator (such as an RC filter with the same time constant), i.e. R _fC_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, the M _R 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 isolation probe to maintain the isolation advantage of the rogowski coil. The compensation pole can take a variety of forms, including various architectures of RC (resistor capacitor) filters or LR (inductor resistor) filters.

Since DC and low frequencies are handled by shunt action, the rogowski coil inductance can be optimized for high frequency operation. This allows the design to have a smaller coil inductance and higher frequency coverage than an independent rogowski coil.

Fig. 13 shows a block diagram of a test and measurement system comprising a current measurement device in the form of a current shunt. It should be noted that this figure shows several components that are not needed for the current measurement device, but provides context for various embodiments of the device. In fig. 13, a Device Under Test (DUT) 1110 has a current measurement device 1112 attached to it. The current measuring device may comprise built-in or "welded" components, or attachable/detachable components. The DUT will typically be connected to test and measurement instrumentation 1120 through one or more probes 1114. In some cases, one or more probes may include an "isolation probe" in which the probe is galvanically isolated from the instrument. For higher voltage and frequency operation, including those with Wide Bandgap (WBG) devices, the isolation probe allows for more accurate measurements and reduces shock hazards.

As will be discussed in more detail later, one or more filters at the instrument level may receive the output of the measurement device 1112. These are different from the compensation pole filters discussed above. The filter 1116 may take the form of a separate 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.

The rogowski coil may be implemented in a two-layer (or more) flexible circuit board which may then be wound and soldered onto a bus bar or surface mount metal alloy shunt 1130, such as shown in fig. 14A-14D. A coil may be wrapped around the resistive portion 1132 or 1136 of the shunt 1130, and the shunt 1130 may typically be made of manganese copper. In the embodiment of FIG. 14A, sense leads such as 1134 protrude from the shunt strip. Fig. 14B-14D illustrate different embodiments of the resistive portion 1132 or 1136 in the middle of the copper portion.

Fig. 15 and 16 illustrate current measurement devices including a combined shunt with a sense lead and a rogowski coil in various embodiments. In a single ended implementation, shown in fig. 15, a reference to a shield, which may include an isolation probe or isolation barrier, may be connected to one side of the shunt 1140. Rogowski coil 1141 may be connected to the other side of the shunt, with one end of R _f connected to the coil, the other end of R _f connected to C _f and the input of the probe, and the other end of C _f connected to the probe reference.

A set of traces, indicated by 1142, is formed on a layer of the flex circuit closest to the shunt. Another set of traces, indicated by 1144, are formed on the opposite side of the flex circuit layer from the shunt. In some embodiments, the flex circuit may have an insulating layer or flexible dielectric core between the layer with trace 1142 and the layer with trace 1144, and in some embodiments may also have an insulating layer as the topmost and bottommost layers of the flex circuit. Trace 1142 is connected to trace 1144 through a via in the flex circuit such that the trace and via form a continuous conductive rogowski coil structure in the flex circuit. When a coil is wound around the shunt, this causes a magnetic field around the shunt to flow between the two sets of traces. The portion of the trace labeled Mc is placed as close as possible to the shunt and opposite the return current path to form the cancellation mutual inductance. The rogowski coil portion is then at least partially wound 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 an isolation barrier, and in yet another embodiment, the isolation barrier is present in the probe. The coil output may also be connected to a fixed time constant monopole compensator 1146. Fig. 15 shows an embodiment comprising an RC filter with a filter resistor R _f and a filter capacitor C _f.

Fig. 16 shows a differential signaling embodiment. In a differential implementation, shielding portions of the isolation barrier, such as the shielding of the isolation probe, may be connected to either side of the shunt. Half of the rogowski coil 1151 may be placed on each side of the shunt to feed the differential signal through the compensation pole 1156. This can be fed from side to side of the differential probe input to R _f/2 to C _f on each side. Alternatively, C _f may be replaced with two capacitors 2·c _f from each signal line to the reference. In another embodiment, the differential transmission line may be periodically "twisted" to counteract the pick-up of stray electromagnetic fields.

Fig. 17 shows an embodiment of a shunt with a rogowski coil in a busbar embodiment, where the rogowski coil is sandwiched within a folded busbar shunt. The bus bar shunt 1170 has a resistive portion 1172. The shunt is folded in half to reduce the insertion inductance and the two screw terminals (such as 1173) are placed on the same shaft 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 the other 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 flex 1176 connects it to an isolation barrier or probe. The traces on the flexible wires of the coil and the compensating pole components are not shown.

Fig. 18 shows an embodiment of a surface mount shunt having a flex circuit 1180 underneath, the flex circuit 1180 being located between the shunt and a return path in the circuit board on which the shunt is to 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 by a portion 1181 of flexible circuit 1180 and connected to each metal portion (such as 1182) on either side of the shunt. In this figure, the flex circuit trace forming the rogowski coil is 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.

Many modifications and variations exist. For example, the filter resistor R _f may be used as a termination of the transmission line between the shunt/coil and the filter, allowing the probe to be placed at a distance from the shunt while still maintaining a high bandwidth. This allows the shunt to be placed very close to the load without providing additional space for the probe, thereby minimizing the insertion inductance.

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

If the return current path is well defined, such as for a surface mounted shunt on a return planar layer within the 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 in the current loop and thus this arrangement will achieve a mutual inductance almost as large as a complete enclosure, but with a rather low self-inductance. This arrangement also avoids through holes in the sharp bend around the sides of the shunt for implementing coils in the flex circuit, thereby reducing the likelihood of through hole cracking.

The compensation filter time constant may be matched to the M _R/R time constant in any combination of ways. For example, in one embodiment, the shunt and rogowski coil may be built together as a single unit with appropriate component values. This may take the form shown in fig. 17 or 18, as examples.

Another embodiment provides for the selection of a fixed time constant filter suitable for a given shunt rogowski coil pair. This may be implemented in filter blocks 1146 and 1156 of fig. 15 and 16, respectively. In yet another embodiment, the filter block may provide one or more programmable filters, such as using FETs to switch capacitors in the capacitor DAC of C _f. The response pole due to the loading of the filter resistor R _f on the self-inductance of the rogowski coil can be compensated with a corresponding zero by placing some resistor in series with C _f. In yet another embodiment, the rogowski loop region and/or the pitch may taper along the length of the coil such that the mutual inductance M _R may be adjusted by sliding the appropriate portion of the tapered coil under the shunt.

With respect to the system shown in FIG. 13, the acquired signal from the probe can also be used as it enters the instrument to adjust the difference between 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 may take the form of a DSP pole-zero filter applied to the acquired waveform to cancel any remaining filter time constant mismatch. Furthermore, if the M _R ·di/dt term is insufficient to dominate the r·i term at frequencies where the skin effect begins to significantly change the effective resistance R, the filter 1116 may comprise an analog and/or DSP filter applied to compensate for the resulting error in the crossover region between the shunt and rogowski dominated responses.

Fig. 19 shows an embodiment of a gasket current shunt 1200 similar to those set forth above. Embodiments herein include 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 (top to bottom as shown in the figure) through which a screw is to be inserted. While there are many different ways of providing the rogowski coil, and other structures for including it within a washer current shunt, one possible embodiment is to manufacture the rogowski coil as a Printed Circuit Board (PCB).

Similarly, for other embodiments of the rogowski coil and shunt resistor discussed above, the signals from the rogowski coil and shunt resistor may be combined by a test and measurement apparatus. The combination may comprise a coil placed in series with a shunt resistor or by combining the two signals by summing them together. The shunt resistor and the coil may be wired in parallel and their combination of signals applied by the test and measurement equipment.

Fig. 20 shows a more detailed view of one of the resistive core and the conductive surface. As shown here, the resistor core 1208 has a contact area on an end face of the core 1216. The other end face has the same contact area. The insulating layer surrounds the core much like a coil structure, up to the outside of the resistive core, to allow the core to contact the conductive surface.

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

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 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.

Fig. 23 shows an assembled current measurement device having conductive layers 1202 and 1210 in contact with a resistive core 1208. The rogowski coil structure 1206 is separated from the conductive layer by one or more insulators 1204 and the entire assembly has a central opening 1214 to allow insertion of a screw or other fastener.

The contacts on the rogowski coil may be electrically connected to the resistive core to place them 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 by a sense lead 1220. One example shown in fig. 23 uses a top conductive surface. The other electrical contact has a measurement lead 1222. Another measurement lead 1224 is electrically connected to another conductive surface of the structure.

Alternatively, the insulating layer may have a gap or a groove. In one embodiment, the insulating layer has the shape of the letter "C". This allows the connection of the measurement leads 1226 to the rogowski coil electrical contacts to come directly from the top surface of the resistive core. The measurement lead 1222 will be identical and the other measurement lead 1228 will directly contact the resistive core and exit through a slot or gap in the lower insulating layer now shown.

In this way, a washer current shunt having a shunt resistor and a rogowski coil to allow for the insertion of the form factor of the fastener may be provided.

In another embodiment, the coil is present in a flexible circuit substrate as discussed above, but in a multilayer embodiment that can provide improved cancellation of the magnetic field. Fig. 24 shows a flexible substrate 1230 having multiple layers. The first layer 1232, shown in a set of single hash marks, has a first set of coil traces and contact points, such as 1238, that define vias between layers. A second layer 1234 with a single hash mark in the opposite direction has a second set of coil traces and contact points for the other "end" of the via. The first and second coil traces are configured such that one set partially overlaps the other set in the first dimension. The coil structure is connected to the shunt resistor in any of the ways discussed above.

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

The two sets of coil traces form a rogowski coil. One of the vias (such as 1238) between the first and second layers, the first series of coil traces and first contacts and the second series of coil traces and second contacts forming the rogowski coil, and the first and second contacts is connected to a shunt resistor. In the embodiment of fig. 24, the rogowski coil has a single ended output signal. The substrate is connected to a rogowski coil, as shown in the earlier embodiments discussed above, and has similarly configured sense leads. In the embodiment of fig. 24, the rogowski coil has a single ended output signal. The substrate is connected to a rogowski coil, as shown in the earlier embodiments discussed above, and has similarly configured sense leads.

The embodiments in fig. 24-28 have the advantage that there is no current loop area in the dimension perpendicular to the coil structure. This provides better cancellation and thus more accurate measurements.

Fig. 25 shows an embodiment of a third layer 1240 represented by a center trace. 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. Further, the trace on the third layer at the center of the coil acts as a return current path. The center trace may be wider than the other traces to provide this mechanical stability.

Fig. 26-28 illustrate embodiments in which the rogowski coil has a differential output signal. When two coils overlap, the relationship between them may define the manner in which the coils operate. In the figures, the coil is defined by a through hole from top to bottom. In the embodiment of fig. 26, the vias define an A-coil and A B-coil, wherein the coils have an A-B-A-B 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 coil that are used to locally cancel the magnetic field in the z-direction.

In fig. 27, the top-to-bottom vias are associated with coils in the A-B-A pattern. This results in a coil structure centered in the x-direction but having a different dimension 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.

Fig. 28 shows A coil structure in which the coil again has an A-B-A structure centered on the x-direction but different in the y-direction. Although the wound trace around the outside of the coil is used to cancel the field in the z-direction, each loop at one end of the coil has its complement at the other end in the y-direction. This counteracts a field spanning a greater distance than the local counteraction embodiment described above.

Fig. 29 shows an embodiment of a coil structure 1250 implemented in a rigid substrate (such as ceramic or glass). This type of substrate may have advantages in Surface Mount Technology (SMT) and is capable of manufacturing coil structures at the wafer level using thin and thick film processes. They will then be cut to produce individual current measuring devices. Fig. 29 shows a detailed view of the conductive structure without the substrate.

The coil structure has a metal trace (such as 1252) on a first surface of the rigid substrate. Vias (such as 1254) connect those traces with traces on the bottom surface (such as 1256). This forms a 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 not shown in fig. 29, a center trace through the middle of the coil structure may be included to provide a return path, similar to 1240 in fig. 25.

In one embodiment, discrete SMT resistors are laminated or otherwise mounted on top of the coil substrate by soldering, adhering to exposed pads, etc. In any embodiment, the resistor may be mounted above the central axis of the coil structure to provide a return path. A thin film resistive material or solder mask (soldermask) prevents shorting of the coil to the resistor. In 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 and contact pads 1258 and 1260 and their counterparts providing kelvin sensing can be seen.

Alternatively, the thin film process of forming the coil may be adapted to include a shunt resistor. As shown in fig. 31, after forming the coil in the substrate, an insulating layer 1264 may be deposited on the coil structure. A resistive layer 1266 would then be deposited over the insulator to overlap to connect to the conductive surface. The process is well suited for wafer level thin and thick film processes.

Fig. 32 shows the current and field patterns of a current monitor including a shunt resistor and rogowski coil in a rigid substrate. Arrows (such as 1268) illustrate current flow, with darker shading (such as 1273) representing the conductive material, including coil structure 1274. Measurement contacts are shown at 1271 and 1272. A resist 1270 is located on insulator 1269. The magnetic field lines are shown by black dots (such as 1276). The field lines represented by the black dots may be located anywhere within the current loop specified by the arrows.

Fig. 33 illustrates a method of manufacturing a rogowski coil in a rigid substrate. At 1280, the substrate is subjected to masking and patterning with a via pattern. Typically, the mask covers portions of the substrate to be retained and exposed portions to be removed, although vice versa. If the substrate is glass, the substrate is baked at 1282 to convert the exposed region to 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 via, such as 1274. Conductive material is then deposited into the vias, such as by electroplating at 1286. A thicker metal layer is then deposited onto both the top and bottom surfaces of the substrate at 1288. It is then masked, patterned and processed, such as by etching, at 1290 to form coil traces connecting the vias and contact pads and other conductive portions. As discussed above, the shunt resistor is connected at 1292 by lamination and soldering/pasting or by deposition of insulator and resistive layers.

Example

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.

Example 1 is a current measurement device comprising a shunt resistor having a measurement lead, the shunt resistor comprising a resistive core having an opening, the shunt resistor configured to be positioned in a current path of a current to be measured, a rogowski coil surrounding the resistive core, the rogowski coil having an electrical contact, 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, and one or more insulating layers between each of the conductive layers and the rogowski coil, the current measurement device configured to combine signals from the shunt resistor and the rogowski core.

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.

Example 3 is the current measurement device of example 1 or 2, wherein the resistive 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 one of the measurement leads.

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 a first side of the resistive core.

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

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 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.

Example 7 is the current measurement device of any one 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.

Example 8 is the current measurement device of any one of examples 1 to 7, wherein the rogowski coil comprises a coil in a printed circuit board.

Example 9 is a current measurement device comprising a shunt resistor having a sense lead, the shunt configured to be positioned in a current path of a current to be measured, and a rogowski coil at least partially wound on a flexible substrate around the shunt, the current measurement device configured to combine signals from the shunt resistor and the rogowski coil.

Example 10 is the current measurement device of example 9, wherein the rogowski coil is configured such that no loop region exists in a dimension perpendicular to the rogowski coil.

Example 11 is the current measurement device of any of examples 9 or 10, wherein the rogowski coil comprises a first layer of flexible substrate comprising 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 at least partially covering the first series of coil traces and first contact points in the z-direction, and a via between the first layer and the second layer, the first series of coil traces and first contact points and the second series of coil traces and second contact points forming a rogowski coil, and one of the first contact points and the second contact points being connected to a shunt resistor.

Example 12 is the current measurement device of example 12, further comprising a third layer between the first layer and the second layer.

Example 13 is the current measurement device of example 12, wherein the third layer comprises a trace located at a center of the rogowski coil to act as a return path.

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.

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

Example 16 is the current measurement device of any one of examples 9 to 15, wherein the current measurement device is configured to generate a differential output signal.

Example 17 is the current measurement device of example 16, wherein the first series of coil traces overlie the second series of coil traces such that the first contact points and the second contact points form an alternating A-B-A-B pattern in the y-direction dimension to locally cancel the field in the first dimension.

Example 18 is the current measurement device of example 16, wherein the first series of coil traces overlie the second series of coil traces such that the first contact point and the second contact point form an A-B-A pattern centered in the x-direction and varying in the y-direction to locally cancel the field in the first dimension.

Example 19 is the current measurement device of example 16, wherein the first series of coil traces overlie the second series of coil traces such that the first contact point and the second contact point form an A-B-A pattern centered in the x-direction and having opposite loops at ends in the y-direction to cancel the field at A greater distance than the locally cancel coil.

Example 20 is a current measurement device comprising a rigid substrate having a top surface and a bottom surface, a via passing through the rigid substrate from the top surface to the bottom surface, the via filled with a conductive material, conductive layers connected to the via 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.

Example 21 is the current measurement apparatus of example 20, wherein the rigid substrate is one of glass or ceramic.

Example 22 is the current measurement 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 the rigid substrate, the top surface has exposed contact pads electrically connected to the coil structure, and the shunt resistor is present on the insulating layer on the top surface of the rigid substrate and is electrically connected to the exposed pads.

Example 23 is the current measurement device of any of examples 20 to 22, wherein the shunt resistor is centered above a central axis of the coil structure.

Example 24 is the current measurement device of any one of examples 20 to 23, wherein the device further comprises a conductive trace through a middle of the coil structure to provide a return path.

Example 25 is the current measurement 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 comprises a layer of resistive material on the at least one insulating layer and in contact with the conductive layer on the top surface.

Example 26 is a method of manufacturing a current measurement device comprising masking a rigid substrate with a pattern of vias, removing portions of the substrate to form holes through the substrate, depositing a conductive material to form conductive vias in the holes, and depositing a second layer of conductive material on 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 the 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 connecting shunt resistors to the rogowski coil structure.

Example 27 is the method of manufacturing of example 26, wherein the rigid substrate comprises glass, and masking the rigid substrate with the pattern of through holes comprises baking the rigid substrate to convert the exposed regions to ceramic prior to removing portions of the substrate.

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

Example 29 is the method of manufacturing of any of examples 26 to 28, wherein connecting the shunt resistor includes depositing one or more insulating layers over the coil structure, and depositing a resistive material over the one or more insulating layers.

Example 30 is the method of manufacturing of any one of examples 26 to 29, further comprising passivating the second layer of conductive material on the top and bottom surfaces prior to connecting the shunt resistor.

Example 31 is the method of manufacturing of examples 26 to 30, wherein the plurality of current measurement devices are manufactured at a wafer level and then cut to produce individual current measurement devices.

While specific aspects of the disclosure have been illustrated and described for purposes of description, it will be appreciated that various modifications may be made without deviating from the spirit and scope of the invention. Accordingly, the invention should not be limited except as by the appended claims.

Furthermore, the written description references specific features. It is to be understood that the disclosure in this specification includes all possible combinations of those particular features. For example, where a particular feature is disclosed in the context of a particular aspect, that feature may also be used in the context of other aspects, insofar as possible.

Furthermore, when reference is made in the present disclosure 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.

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

Although specific examples of the invention have been illustrated and described for purposes of description, 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.

Claims (31)

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; and 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; and 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; and 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 A-B-A-B pattern in the y-dimension to locally cancel the field in the first dimension. 18. The current measurement apparatus of claim 16, wherein the first series of coil traces overlap the second series of coil traces such that the first contact point and the second contact point form an A-B-B-A pattern centered in the x-direction and varying in the y-direction to locally cancel the field in the first dimension. 19. The current measurement apparatus of claim 16, wherein the first series of coil traces overlap the second series of coil traces such that the first contact point and the second contact point form an A-B-B-A pattern centered in the x-direction and having opposite 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; A shunt resistor directly on one or more insulating layers; and 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.