WO2014036731A1

WO2014036731A1 - Magnetic core for sensor

Info

Publication number: WO2014036731A1
Application number: PCT/CN2012/081167
Authority: WO
Inventors: Huabin Fang; Cunxiao JIA; Xinhui Mao
Original assignee: Honeywell International Inc.
Priority date: 2012-09-10
Filing date: 2012-09-10
Publication date: 2014-03-13
Also published as: CN107103982B; CN104603890B; CN104603890A; CN107103982A

Abstract

A magnetic core is formed of three C-shaped segments (405, 420, 435) that define a first window (450) for receiving a current carrying conductor and a second window (455) for concentrating the magnetic flux from the current carrying conductor towards a flux-responsive sensor (230, 495). The magnetic core may include a first C-shaped core segment (405), a second C-shaped core segment (420), and a third C-shaped core segment (435). The first and second segments may define the first window (450) and the second and third core segments may define the second window (455). In response to the magnetic flux, the flux-responsive sensor (230, 495) may generate an output signal indicative of the primary. The low cost, low permeability three-part magnetic core may be used to accurately sense current using a magnetoresistive sensor or a flux gate based sensor.

Description

MAGNETIC CORE FOR SENSOR

TECHNICAL FIELD

Various embodiments described herein may relate generally to a magnetic core, and more particularly to an improved low cost magnetic core design used with a sensor for electrical current.

BACKGROUND

With the development of smart grid and other applications, for example, current sensors have been demanded more and more. Current sensors detect electrical current in a wire and generate a signal proportional to the incoming electrical current. The signal can be utilized to display the measured current in an ammeter or can be stored for further analysis in a data acquisition system or utilized for control purposes.

Some current sensors employ the use of a magnetic core to concentrate magnetic flux produced by the measured current so as to obtain a more accurate measurement. Some magnetic cores may be comprised of a material having certain permeability which permits the magnetic flux to be concentrated and guided in the core material to a current sensor.

SUMMARY

Apparatus and associated methods relate to a magnetic core formed of three C- shaped segments that define a first window for receiving a current carrying conductor and a second window for concentrating the magnetic flux from the current carrying conductor towards a flux-responsive sensor. In an illustrative example, the magnetic core may include a first C-shaped core segment, a second C-shaped core segment, and a third C- shaped core segment. The first and second core segments may define the first window and the second and third core segments may define the second window, for example. In response to the magnetic flux, the flux-responsive sensor may generate an output signal indicative of the primary current, for example. In an illustrative embodiment, a low cost, low permeability three-part core may be used to accurately sense current using a magnetoresistive sensor or a flux gate-based sensor, for example. Various embodiments may provide one or more advantages. For example, certain embodiments may provide for a cost effective and easy to manufacture magnetic core. In an illustrative example, each core segment may be formed from a unitary or one-piece metal strip employing two right angle bends. For example, each core segment may include a base and a pair of legs formed at opposing ends of the base via a ninety degree bend. The core segments may be positioned along interior and exterior faces of adjacent core segments to form a rectangular -shaped structure which has the first window and the second window, for example. Various embodiments may be readily suited for machine assembly in a high speed production line, for example.

In some implementations, the highly-sensitive flux-responsive sensor used and positioned within the second window may enable the simplified construction and minimal core segments comprising the magnetic core. For example, the highly-sensitive flux- responsive sensor may be able to detect small amounts of magnetic flux concentrated within the second window. In some examples, the highly-sensitive flux -responsive sensor may enable a lower permeable material to be used in forming the core segments, thus providing for a more cost effective magnetic core.

Some embodiments may also retain a printed circuit board within the second window for connecting the flux -responsive sensor. In some examples, the printed circuit board may include process circuitry for configuring an output signal from the flux- responsive sensor. In some examples, multiple flux -responsive sensors may be present upon the printed circuit board. The flux-responsive sensors may also be in various orientations relative the magnetic flux lines, depending upon the type of sensor used, for example.

The details of various embodiments are set forth in the accompanying drawings and the description below. Other features and advantages will be apparent from the description and drawings, and from the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 illustrates an overview of an exemplary field installation for a current assembly.

Figure 2 illustrates a flow diagram of an exemplary sensor assembly.

Figure 3 illustrates an upper perspective view of an exemplary sensor assembly. Figure 4 illustrates an exploded upper perspective view of an exemplary sensor assembly.

Figure 5 illustrates another upper perspective view of an exemplary sensor assembly.

Figure 6 illustrates a cross-sectional view of an exemplary magnetic core for a sensor for electrical current.

Like reference symbols in the various drawings indicate like elements.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

To aid understanding, this document is organized as follows. First, with reference to Figure 1, an overview of an exemplary field installation of a current sensor assembly is illustrated. Second, with reference to Figure 2, an exemplary flow diagram of the magnetic core and flux-responsive sensor is illustrated. Finally, with reference to Figures 3 through 6, exemplary construction views of the magnetic core and flux -responsive sensor are illustrated.

Figure 1 illustrates an overview of an exemplary field installation for a sensor assembly. The exemplary field installation is shown as a power distribution network 100. The power distribution network 100 includes a generating station 105 arranged to provide bulk power. The voltage at the generating station 105 is stepped up at a transmission substation 110 to a higher transmission level voltage for more efficient transfer of electricity via transmission lines 115.

At a down line distribution substation 120, voltage is reduced for distribution over local distribution lines 125. As depicted, the voltage is further reduced to supply the electricity via secondary lines 130 to a residential customer 135.

The amount of electricity used by the customer 135 is monitored through a meter 140 having a sensor assembly 145 with a magnetic core. The magnetic core provides a magnetic flux path. The sensor assembly 145 detects a magnetic flux associated with the current flow delivered through the meter 140. The sensor assembly 145 includes a sensing module for detecting the magnetic flux to generate an output signal in response to a current flow. The reference arrow leading to the sensor assembly 145 represents the incoming primary current (Ip) that flows through an opening in the magnetic core. The reference arrow I* at the output of the sensor assembly 145 is a measurement signal that represents the time-varying waveform of the primary current Ip. In some examples, the signal I* may be transferred to a control center or central database in real time. In some embodiments, the signal I* may be retained internally for later retrieval or evaluation. The sensor assembly 145 may be connected to a closed-loop or open-loop signal-processing architecture, examples of which will be described in further detail with reference to Figure 2.

Figure 2 illustrates a flow diagram of an exemplary sensor assembly. A sensor assembly 200 is arranged to receive an incoming primary current 205 that is magnetically coupled to a magnetic core 210. In the depicted example, the magnetic core 210 is also arranged with a secondary winding, which is coupled to receive a secondary current signal 215 from an external circuit 220 (e.g., amplification, signal conditioning, and/or signal processing). In some examples, an amplitude of the secondary current 215 may be substantially less than an amplitude of the primary current 205.

As the primary current 205 passes through the magnetic core 210, magnetic flux 225 may be caused to flow along a path formed by the magnetic core 210 and detected by a sensing module comprised of a flux-responsive sensor 230. The amount of magnetic flux 225 in the magnetic core 210 may be indicative of the magnitude of the primary or secondary current 205, 215. The flux-responsive sensor 230 has leads connected for power 235, ground 240, and signal 245.

In a closed-loop type sensor system, the signal 245 from the external circuit 220 may be connected to a secondary and/ or a tertiary winding on the magnetic core 210 to provide an accurate and sensitive secondary current 215. In some examples, the external circuit 220 may be arranged to drive a compensating current that substantially offsets the magnetic flux 225 in the core 210 being generated by the primary current 205. As a result, the external circuit 220 may operate to substantially maintain the total flux in the core at substantially near or at zero. In an illustrative embodiment, the external circuit 220 comprises an amplifier with positive and negative input terminals coupled to the differential output signal of the sensor 230, and an output terminal coupled to the secondary winding, for example. The output signal 215 may be driven by an operational amplifier circuit, in some examples. The external circuit 220 may provide an output signal 250, which may be relayed to a database or control center as the output current signal 250, for example. In an illustrative example, the output signal 250 signal 215 may be generated by the current signal 215 that flows through secondary windings on the magnetic core 210 and then through a resistive element, where it produces a voltage signal that is an accurate, scaled, linear representation of the primary current signal 205. In some implementations, the return path of the signal 245 to the magnetic core 210 may be omitted with the signal 245 being directly output as an open-loop type.

Some embodiments may provide access to either or both the open loop signals 245 and/or closed-loop output signals 250. Various embodiments may provide additional post- processing, signal conditioning, amplification, analog or digital multiplexing, filtering, and may be sampled by an analog-to-digital converter to generate a digital representation of either or both of the signals 245, 250. In some examples, the flux-responsive sensor 230 may be highly sensitive. Highly sensitive flux-responsive sensor 230 may advantageously facilitate use of reduced core material (e.g., cross sectional area) and/or enable use of reduced permeability core materials. Such reductions may yield savings in weight, size, and cost, for example. Such embodiments may advantageously enable novel core designs that employ simplified construction, in accordance with various embodiments described herein. Simplified core designs may yield compound benefits with respect to savings in assembly with respect to construction of the magnetic core 210 to form embodiments of a current sensor assembly.

In one example, the highly sensitive flux-responsive sensor 230 may include a tunnel magneto resistance (TMR) sensor. In another example, the highly sensitive flux- responsive sensor 230 may be comprised of an anisotropic magneto resistance (AMR) sensor. In another example, the highly sensitive flux-responsive sensor 230 may be comprised of a flux gate based sensor. In still other examples, the flux -responsive sensor 230 may comprise a type of sensor not as highly sensitive such as a Hall magnetic sensor. For TMR, AMR, flux gate magnetic sensors, the sensitive direction of the flux-responsive sensor 230 may be oriented with flux responsive components approximately in parallel with a magnetic flux guided to the sensor via the core 210. For Hall magnetic sensors, the sensitive direction of the flux-responsive sensor 230 may be oriented substantially perpendicular to a flux vector in the core 210.

The use of highly sensitive flux-responsive sensors 230 may also permit the magnetic core to be formed of one or more materials having a reduced magnetic permeability. For example, the highly sensitive flux-responsive sensors 230 may be able to accurately detect much smaller amounts of magnetic flux 225, thus affording lesser requirements for the magnetic core to intensify and concentrate the magnetic flux 225 towards the flux-responsive sensor 230. Because of the greater freedom in material permeability selection, a wider variety of materials may be used to construct the core, thus permitting the use of more cost effective materials. By way of example and not limitation, the material used to construct the magnetic core 210 may comprise, for example, permalloy. In some examples, the material used to construct the magnetic core 210 may include, for example, a soft magnetic material.

Figure 3 illustrates an upper perspective view of an exemplary sensor assembly. A sensor assembly 300 includes a magnetic core 305 adapted to concentrate and provide a path for the magnetic flux produced by a current to be measured. The magnetic core 305 has no more than layers for ease of construction as well as a reduction in cost. For example, the layers of the magnetic core 305 may comprise one or two layers of a material having a relative magnetic permeability substantially greater than unity.

The magnetic core 305 defines a first window 310 and a second window 315 for providing a magnetic flux path. In the depicted example, the first window 310 is of a much larger size and area than the second window 315 in Figure 3 such that the magnetic flux lines generated in the first window 310 may be concentrated in the smaller-sized second window 315. In some examples, the first window 310 and the second window 315 may have approximately equal areas. In other examples, the second window 315 may be of a greater area than the first window 310. For example, when employing multiple circuits in the second window 315, the size of the second window 315 may be larger to accommodate the multiple circuits. In some examples, the circuits may be highly sensitive to permit accurate measurements of the magnetic flux with a larger sized second window 315.

The sensor assembly 300 includes primary current conductors 320 passing through the first window 310 of the magnetic core 305. The primary current conductors 320 may comprise a multi-phase arrangement or a single-phase arrangement, for example. The primary current conductors 320 may be looped through the first window 310 once or multiple times, for example. The sensor assembly 300 also includes a pair of bobbins 325 encircling upper and lower legs of the magnetic core 305 along the first window 310. The bobbins 325 receive secondary current conductors 330 which are wound around the bobbins 325. The number of turns of the secondary current conductors 330 around the bobbins 325 may vary and is proportional to the magnitude of the outputted, secondary current passing through the secondary current conductors 330 relative the primary current passing through the primary current conductors 320.

The sensor assembly 300 includes a printed circuit board 335 disposed within the second window 315 of the magnetic core 305. The printed circuit board 335 includes a flux-responsive sensor for sensing magnetic flux generated within the first window 310 by primary and secondary current conductors 330. The printed circuit board 335 also includes various signal-processing circuitry. For example, the processing circuitry may filter or condition (e.g., amplify) or otherwise process the measured signal. In some implementations, the processing circuitry may digitally sample and hold, or eve convert the analog output signal to a digital representation, for example, in the form of a signal representing a numeric value indicative of the primary or secondary current amplitude and/or phase information.

In the depicted example, the printed circuit board 335 has a power lead 340 for providing an operating voltage thereto from an external source (not shown). The printed circuit board 335 also has a ground lead 345 to couple to the external source. The printed circuit board 335 also has a signal output lead 350 connectable to a sensing module for detecting a magnetic flux within said second window 315 to generate an output signal in response to a current flow through said first window 310. In some examples, the signal output lead 350 is directed towards a data storage device either local or remote. In other examples, the signal output lead 350 is directed towards a real-time control center. The signal 350 from the signal output lead 350 may be transferred through a wired connection in some examples, or through a wireless connection in other examples. In some examples, the printed circuit board 335 may include necessary wireless transmission hardware for wirelessly transmitting the signal direct from the printed circuit board 335. In some embodiments, an optical output signal source may modulate (e.g., amplitude to intensity, amplitude to frequency) to output an encoded signal representative of the primary current 320.

The magnetic core 305 is housed upon or within a casing 355. The housing may be, for example, formed (e.g., potted or injection molded) into forms of various shapes and sizes to contain or protect at least a portion of the core 305, bobbins 325, windings 320, 330, and/or circuit board 335, for example.

Figure 4 illustrates an exploded upper perspective view of an exemplary sensor assembly. A sensor assembly 400 includes the magnetic core as previously discussed in reference to Figure 3 to provide a magnetic flux path. The primary and secondary current conductors as well as the casing and leads have been omitted from the sensor assembly 400 of Figure 4 so as to focus on the construction of the magnetic core.

The magnetic core of the sensor assembly 400 includes a first core segment 405 having an elongated base 410 and opposing legs 415 extending from opposite ends of the elongated base 410 to form a C-shaped structure, a second core segment 420 having an elongated base 425 and opposing legs 430 extending from opposite ends of the elongated base 425 to form a C-shaped structure, and a third core segment 435 having an elongated base 440 and opposing legs 445 extending from opposite ends of the elongated base 440 to form a C-shaped structure.

The first core segment 405, second core segment 420, and third core segment 435 each employ a rectangular-shaped cross-section. Also as shown in Figure 4, the opposing legs 415, 430, 445 of each of the respective core segments 405, 420, 435 parallel each other, and the bases 410, 425, 440 of the first, second, and third core segments 405, 420, 435 parallel each other. Additionally, the bases 410, 425, 440 of the first, second, and third core segments 405, 420, 435 are perpendicular to the respective legs 415, 430, 445. In other examples, the legs 415, 430, 445 or bases 410, 425, 440 of one or more of the core segments 405, 420, 435 may be arcuate or take on the form of other shapes. The first window 450 and the second window 455 are formed by the interconnection of the first core segment 405, the second core segment 420, and the third core segment 435 and form the magnetic flux path.

As shown in Figure 4, the first core segment 405, the second core segment 420, and the third core segment 435 each comprise a one-piece structure. Each core segment 405, 420, 435 also employs two bends for forming the opposing legs 415, 430, 445 respective of the base 410, 425, 440. The one-piece and minimal shaping to form the respective core segments 405, 420, 435 allow for a simple and cost effective construction of the core segments 405, 420, 435. The minimalist construction of the magnetic core via the one-piece first core segment 405, second core segment 420, and third core segment 435 is possible because of the highly sensitive flux-responsive sensors used in conjunction with the magnetic core.

Also shown is a pair of bobbins 460 as previously described for receiving the secondary current conductors. The bobbins 460 have an interior lumen sized for receiving the legs 415, 430, 445 of the first core segment 405, second core segment 420, and third core segment 435. Each bobbin 460 has a first end plate 465 having a notch 470 along an outer face sized for receiving the base 410 of the first core segment 405. The bobbin 460 also has a second end plate 475 at an opposing end and also having a notch 480 along an outer face sized for receiving the base 425 of the second core segment 420. Extending between the first end plate 465 and the second end plate 475 is a central portion 485 in which the secondary current conductors are wound around. The central portion 485 may employ a rounded, square, or rectangular cross-sectional shape along an exterior side in various examples. In some examples, the central portion 485 may employ rounded corners along an exterior side to minimize damage to the secondary current conductors when tightly wound around the central portion 485.

A printed circuit board 490 is retained within the second window 455 defined by the second core segment 420 and third core segment 435. The printed circuit board 490 has slots for receiving the legs 445 of the third core segment 435. In construction, the interior side of the printed circuit board 490 may be positioned in a flush manner against the exterior side of the second end plate 475 to form a compact magnetic core construction. The printed circuit board 490 may also be glued to the base 425 of the second core segment 420 or the second end plate 475 to fixedly retain the printed circuit board 490, for example. As previously described, the printed circuit board 490 includes the sensing module comprised of a flux-responsive sensor 495 for detecting a magnetic flux within said second window 455 to generate an output signal in response to a current flow through said first window 450.

Figure 5 illustrates another upper perspective view of an exemplary sensor assembly. The sensor assembly 500 includes the magnetic core 505 having a first core segment 510, a second core segment 515, and a third core segment 520 to define the first window 525 and the second window 530 as previously discussed in reference to Figure 4. The core segments 510, 515, 520 define the first window 525 and second window 530 and provide a magnetic flux path.

The first window 525, as previously described, is defined by the first core segment 510 and the second core segment 515. In construction, the opposing legs of the second core segment 515 are received along an interior face of the opposing legs of the first core segment 510 and abut an interior face of the elongated base of the first core segment 510 to form the first window 525. The second window 530, as previously described, is defined by the second core segment 515 and the third core segment 520. In construction, the opposing legs of the third core segment 520 are received along an exterior face of the opposing legs of the second core segment 515 and abut outer ends of the opposing legs of the first core segment 510 to form a second window 530 defined by the second core segment 515 and the third core segment 520.

Also shown in Figure 5 is an example of a sensor element 535 (shown with printed circuit substrate removed) that is sandwiched between the base of the second core segment 515 and the base of the third core segment 520. In one example, the sensor element 535 is fixed within the second window 530 between the bases via an adhesive such as glue, for example. The sensor element 535 includes a plurality of highly-sensitive sensing modules comprised of flux-responsive sensors 540 for detecting a magnetic flux within said second window 530 to generate an output signal in response to a current flow through said first window 525.

Figure 6 illustrates a cross-sectional view of an exemplary magnetic core for a flux-responsive sensor. The exemplary magnetic core 600 provides a magnetic flux path and has a first window 605 and a second window 610. The first window 605 and the second window 610 are different sizes, with the first window 605 being substantially larger than the second window 610 so as to allot space for winding of primary and secondary conductors in the first window 605 and to concentrate the magnetic flux within the second window 610 for being read by a flux-responsive sensor (not shown in Figure 6). The illustrative embodiment may also include a sensing module for detecting a magnetic flux within said second window 610 to generate an output signal in response to a current flow through said first window 605.

Exemplary dimensions are also given in Figure 6. By way of example and not limitation, a height H of the magnetic core is about 14 millimeters. A length L of the magnetic core is about 20 millimeters. A thickness T of the magnetic core is about 0.4 millimeters. A width of the magnetic core is about 3 millimeters. In an exemplary arrangement of the magnetic core, a primary current supplying 30 amps looped through the first window, and a secondary feedback coil wrapped 1000 turns around the legs of the magnetic core also within the first window may provide a magnetic field approximately equal to 106 gauss within the second window. By way of example and not limitation, the relative permeability of the magnetic core in the previous example may be about 2500 μ₀, for example.

Although various embodiments have been described with reference to the Figures, other embodiments are possible. For example, the magnetic core may comprise a one- piece structure or may comprise a multi-piece structure. For example, in the multi-piece structure, the magnetic core may include first, second, and third core segments connected together to provide an optimal flux path arrangement. In a one-piece structure, the magnetic core may be cast in a solid one-piece form, for example.

In various examples, the magnetic core employs a rectangular-shaped cross-section. In some examples, the magnetic core may employ a circular -shaped cross-section. In yet other examples, the magnetic core may employ a square-shaped cross-section with equal length width and height. In some examples, each core segment may be symmetrical. In other examples, the core segments may be non-symmetrical. For example, the respective legs of the core segments may be different lengths.

In some examples, the length of the legs of the first core segment may be similar to the lengths of the legs of the second and third core segments. In other examples, the lengths of the legs of the second core segment may be longer than the lengths of the legs of the first and third core segments. In some examples, the core segments may be assembled to form a rectangular shaped magnetic core. In other examples, the core segments may be assembled to form a cylindrical shaped magnetic core or a square shaped magnetic core.

In various examples, the magnetic core and attached flux-responsive sensor may be assembled by hand. The magnetic core employs a minimal number of bends and is comprised of a unitary structure thus providing for a simple manufacturing and assembling process, for example. In some examples, the magnetic core and attached flux-responsive sensor may be assembled by machine. For example, during manufacturing, the magnetic core may be formed via a mold.

The core segments may form a smooth, linear structure in some examples. Other examples may benefit from a jagged or non-smooth exterior or interface face of the core segments. In some examples an interlocking piece may extend from one or more core segments for connecting the adjacent core segments such as to prohibit relative movement between core segments. For example, an aperture and locking pin arrangement may be employed between adjacent core segments.

In some examples, the first core segment, second core segment, and/or third core segment may adjust relative each other to adjust the size of the respective defined window. For example, the first core segment and the second core segment may slide apart relative each other to increase the width of the first window if more space is needed for an increased number of turns in the secondary current conductors. In some examples, the second core segment and the third core segment may slide together relative each other to decrease the width of the second window thus providing a more confined space to concentrate the magnetic flux which may provide for a more accurate measurement.

The adjustment of the core segments relative to each other may be made manually, for example, where the first core segment may be manually pulled away from the second core segment to increase separation. In some examples, a motor or actuator may be employed to automate the adjustment of the core segments relative each other. For example, if the magnetic field concentrated within the second window is deemed too weak, an actuator may adjust the width of the second window. In other examples, magnetic core may adjust in size determinant upon an ambient temperature.

The shape, size, and/or position of the printed circuit board may likewise adjust to accommodate the adjusted second window, for example. In some examples, the flux- responsive sensor and printed circuit board may be retained within the second window in a floating manner, such as by being supported by an external object and not being directly connected to the magnetic core, for example. In some examples, the sensor of the printed circuit board may sense and monitor current. The sensor may additionally or alternately sense and monitor magnetic flux, for example.

In some examples, multiple different types of high sensitivity flux-responsive sensors may be used to detect the magnetic field produced by the primary current conductors through the first window. For example, an AMR, TMR, and flux gate based sensor may be employed on a singular printed circuit board. The use of multiple different types of flux-responsive sensors may be useful in experimental arrangements when sizing the first or second window along with the magnetic core. In some examples, one or more the flux-responsive sensors may employ the use of an operational amplifier.

In some implementations, a closed loop current sensor may include a magnetic- flux responsive sensor mounted in an air gap of a magnetic core, a secondary coil wound around the core and a current amplifier. The current carrying conductor placed through the aperture of the current sensor produces a magnetic field that is proportionate to the current. This field is concentrated by the core and sensed by the magnetic -flux responsive sensor. The magnetic-flux responsive sensor is connected to the input of the current amplifier, which drives the secondary coil. The current through the secondary coil produces an opposing field to that provided by the current through the aperture. Thus the flux in the core is constantly driven to zero. The secondary coil connects the output of the current sensor. Therefore the output is a current proportional the aperture current multiplied by the number of turns on the coil. A sensor with a 1000 turn coil provides an output of 1mA per ampere. The current output is converted to a voltage by connecting a resistor to the output of the sensor and ground. The output is scaled by selecting the resistor value. Closed loop sensors measure dc and ac currents and provide electrical isolation. They offer fast response, high linearity and low temperature drift. The current output of the closed loop sensor is relatively immune to electrical noise. They are the sensor of choice when high accuracy is essential. In some implementations, an open loop current sensor may include a magnetic-flux responsive sensor mounted in an air gap of a magnetic core. The current carrying conductor placed through the aperture of the sensor produces a magnetic field that is proportionate to the current. The field is concentrated by the core and measured by the magnetic-flux responsive sensor. Open loop current sensors measure DC and AC currents and provide electrical isolation between the circuit being measured and the output of the sensor.

A number of implementations have been described. Nevertheless, it will be understood that various modification may be made. For example, advantageous results may be achieved if the steps of the disclosed techniques were performed in a different sequence, or if components of the disclosed systems were combined in a different manner, or if the components were supplemented with other components. Accordingly, other implementations are within the scope of the following claims.

Claims

CLAIMS What is claimed is:

1. A magnetic core for a flux-responsive sensor, the magnetic core comprising:

a first core segment (405), said first core segment (405) having an elongated base (410) and opposing legs (415) extending from opposite ends of said elongated base to form a C-shaped structure; a second core segment (420), said second core segment (420) having an elongated base (425) and opposing legs (430) extending from opposite ends of said elongated base to form a C-shaped structure; wherein said opposing legs (430) of said second core segment (420) are received along an interior face of said opposing legs (415) of said first core segment (405) and abut an interior face of said elongated base (410) of said first core segment (405) to form a first window (450) defined by said first core segment (405) and said second core segment (420); and a third core segment (435), said third core segment (435) having an elongated base (440) and opposing legs (445) extending from opposite ends of said elongated base to form a C-shaped structure, wherein said opposing legs (445) of said third core segment (435) are received along an exterior face of said opposing legs (430) of said second core segment (420) and abut outer ends of said opposing legs (415) of said first core segment (405) to form a second window (455) defined by said second core segment (420) and said third core segment (435), and wherein at least one flux -responsive sensor (230, 495) may be disposed in said second window (455) to detect magnetic flux and generate an output signal (250) in response to a current that flows through the first window (450).

2. The magnetic core for a flux-responsive sensor of claim 1, wherein said opposing legs (415, 430, 445) of said first core segment (405), said second core segment (420), and said third core segment (435) substantially parallel each other.

3. The magnetic core for a flux -responsive sensor of claim 1 , wherein said elongated bases (410, 425, 440) of said first core segment (405), said second core segment (420), and said third core segment (435) substantially parallel each other.

4. The magnetic core for the flux -responsive sensor of claim 1 , wherein said first core segment (405) is comprised of a one-piece structure, wherein said second core segment (420) is comprised of a one-piece structure, and wherein said third core segment (435) is comprised of a one-piece structure.

5. The magnetic core for the flux -responsive sensor of claim 5, wherein said first core segment (405), said second core segment (420), and said third core segment (435) each have a substantially rectangular cross-section.

6. The magnetic core for the flux -responsive sensor of claim 5, wherein said first core segment (405) employs a maximum of two bends, wherein said second core segment (420) employs a maximum of two bends, and wherein said third core segment (435) employs a maximum of two bends.

7. The magnetic core for the flux -responsive sensor of claim 1 , wherein said at least one flux-responsive sensor (230) is comprised of a tunnel magneto resistance sensor.

8. The magnetic core for a flux -responsive sensor of claim 1, wherein said at least one flux-responsive sensor (230) is comprised of an anisotropic magneto resistance sensor.

9. The magnetic core for the flux -responsive sensor of claim 1 , wherein said at least one flux-responsive sensor (230) has a closed-loop output.

10. The magnetic core for the flux -responsive sensor of claim 1 , including at least one bobbin (460) for encircling at least one of said opposing legs (415, 430, 445) of said first core segment (405), said second core segment (420), and said third core segment (435).