Fluxgate current sensor

Abstract

A fluxgate current sensor (1) comprising a fluxgate head (2) and a main conductor assembly (5), the fluxgate head comprising a soft magnetic core (14) and an excitation coil (16) wound thereon, the soft magnetic core surrounding a central channel (20, 20a). The fluxgate sensor further comprises a planar substrate extending through the central channel between a first connection edge (10) and a second connection edge (11), the primary conductor assembly comprising a plurality of stacked primary conductor layers formed on or inside the planar substrate, each main conductor layer is separated from the adjacent main conductor layer through an insulating layer.

Description

[0001] This invention relates to a fluxgate current sensor, and more particularly to a fluxgate current sensor mounted on a circuit board.

[0002] Fluxgate sensors are known to be configured for mounting on an electronic circuit board, suitable for measuring leakage current in a single-phase or multi-phase main conductor assembly passing through its central channel. Unless residual current is generated due to leakage or short circuit in at least one phase, the magnetic fields generated by the main conductors should cancel each other out. Fluxgate sensors are known to include a soft magnetic core surrounded by an excitation coil, which is configured to alternately saturate when an alternating excitation current passes through the excitation coil. An external magnetic field affects this alternating saturation, thus affecting the excitation behavior, the magnitude of which can be determined by measuring this behavior. For residual current sensors, when leakage occurs in at least one phase, the magnetic field generated by the main conductor assembly is not zero, and its magnitude corresponds to the amplitude of the leakage current.

[0003] In some conventional fluxgate sensors 1', as shown in Figure 4, the main conductor 5' is wire-shaped and passes through the circular channel 20' of the annular sensor. This annular core has a certain height, and the main conductor is soldered to the pins of the circuit board 101'. Combined with the height of the annular core, this results in the component's height exceeding that of other electronic components. Given the space requirements of various electronic components, it is necessary to reduce the height of the components on the circuit board. Furthermore, the diameter and position of the wires in the main conductor assembly lead to different spacings between each main conductor and the fluxgate sensor, resulting in incomplete cancellation of the generated magnetic fields. One problem caused by the electric field distribution of the conductors is the need for an electrical shielding layer between the fluxgate sensor and the main conductor to weaken the dipole field effect generated by each wire; such shielding structures also incur additional costs. The production and circuit board assembly costs of such conventional residual current sensors are also relatively high, and the assembly process requires manual intervention. The positioning of the pin connections of the main conductor assembly and the corresponding wiring holes on the circuit board often has slight deviations, making assembly difficult.

[0004] In view of the above, the purpose of this invention is to provide a fluxgate current sensor that is compact, highly accurate, and inexpensive to manufacture and install.

[0005] Advantageously, a low-height fluxgate sensor is provided that can be mounted on an external electronic system circuit board.

[0006] Advantageously, a fluxgate sensor for residual current measurement is provided, which can be mounted on a circuit board of an electronic system and can be automated using conventional electronic component assembly equipment.

[0007] Advantageously, a robust, reliable, and accurate fluxgate sensor for residual current measurement is provided.

[0008] Advantageously, a lightweight fluxgate current sensor is provided.

[0009] In some applications, it is advantageous to provide a fluxgate current sensor that can be easily installed and connected to an external electronic system circuit board.

[0010] In some applications, it is advantageous to provide a fluxgate current sensor that is particularly suitable for residual current measurement.

[0011] In some applications, it is advantageous to provide a fluxgate current sensor that is particularly suitable for measuring residual current in multiphase conductor devices.

[0012] The objective of this invention has been achieved by providing the system according to claim 1. The dependent claims set forth various advantageous technical features of embodiments of the invention.

[0013] The present invention discloses a fluxgate current sensor, including a fluxgate head and a main body assembly. The fluxgate head includes a soft magnetic core and an excitation coil wound around the soft magnetic core. The soft magnetic core surrounds a central channel in the form of an elongated slot.

[0014] The fluxgate sensor also includes a flat substrate extending through the central channel located between a first connecting edge and a second connecting edge. The main body assembly includes a plurality of stacked main conductor layers formed on or inside the flat substrate, each main body layer being separated from an adjacent main conductor layer by an insulating layer.

[0015] In a preferred embodiment, the main body assembly includes a first connecting terminal disposed along a first connecting edge of the substrate and a second connecting terminal disposed along a second connecting edge of the substrate, the first connecting edge being located outside the central channel on one side of the fluxgate head, and the second connecting edge being formed outside the central channel on a second axial side of the fluxgate head.

[0016] In a preferred embodiment, the substrate is in the form of a circuit board, and the dominant body layer is formed on different layers within the circuit board.

[0017] In a preferred embodiment, the first connection terminal includes conductive pads arranged along and spaced apart from adjacent connection terminals, the conductive pads being configured for surface mount soldering connections to conductive traces on an external circuit board.

[0018] In a preferred embodiment, the soft magnetic core of the fluxgate is mounted in the core receiving cavity of the coil support housing, and the excitation coil is wound on the coil support housing.

[0019] In a preferred embodiment, the fluxgate head is mounted within a housing, the housing having a central channel for inserting the substrate forming the main body assembly.

[0020] In a preferred embodiment, each of the main conductor layers of the main conductor assembly includes a central portion connecting the first connection terminal and the second connection terminal, wherein the central portions of the plurality of stacked main conductor layers completely overlap each other.

[0021] In a preferred embodiment, each of the main body layers includes a groove extending from a side edge that extends axially along the central channel.

[0022] In a preferred embodiment, the first and second connecting terminals of each dominant body layer are arranged radially opposite each other with a centerline extending axially along the central channel as the axis of symmetry.

[0023] The present invention also discloses an electronic system comprising a fluxgate current sensor according to any of the foregoing embodiments and a system circuit board having conductive traces, the system circuit board further comprising a fluxgate head receiving cutout, a portion of the fluxgate head being inserted into the fluxgate head receiving cutout (103).

[0024] Further objects and advantages of the present invention will be apparent from the claims, detailed description and drawings, wherein: Figure 1a This is a perspective view of an embodiment of a fluxgate current sensor according to the present invention; Figure 1b yes Figure 1a Exploded perspective view of the embodiment shown; Figure 2a This is a perspective view of an embodiment of a current sensor according to the present invention, which will be assembled onto a circuit board of an external electronic system; Figure 2b This is a view of the current sensor assembled and connected to an external electronic system circuit board. Figure 3 According to an embodiment of the present invention, a perspective exploded view of each layer of the main body assembly in a fluxgate sensor, particularly the three-phase plus neutral line main body assembly, is shown. Figure 4a is a top view of a fluxgate sensor used to measure residual current according to existing technology; Figure 4b is a side view of the sensor shown in Figure 4a.

[0025] See attached document Figures 1a to 3 According to one embodiment of the present invention, the fluxgate sensor 1 includes a fluxgate head 2 to include a circuit board 4 comprising a main body assembly 5.

[0026] The fluxgate head 2 includes a saturated soft magnetic core 14, around which an excitation coil 16 is surrounded. The soft magnetic core 14 may optionally be supported and mounted within a coil support housing 18, which has a core receiving cavity 19 for accommodating the soft magnetic core. The excitation coil 16 may be wound around the coil support housing 18 containing the soft magnetic core.

[0027] The excitation coil and an optional coil support housing 18 can be accommodated within the housing 3. In the illustrated embodiment, the housing includes a base 3a and a cover plate 3b. The base 3a has a cavity for accommodating the fluxgate head 2, and the cover plate 3b is used to enclose the fluxgate head 2 within the housing. Those skilled in the art will understand that the housing 3 can adopt different structural forms. In addition to using separate assembly components of the base and the cover plate, the fluxgate head can also be overmolded with an insulating material, such as plastic.

[0028] Although in one embodiment the fluxgate head 2 has a coil support housing 18 with a cavity 19 for mounting the soft magnetic core 14, in another variation, the coil support housing may be omitted, and the excitation coil may be wound directly on the soft magnetic core. In this case, the conductors constituting the excitation coil 16 may be provided with an insulating layer to provide sufficient electrical isolation and protection for the wires directly wound on the soft magnetic core. Other variations exist where an insulating foil is wrapped around the soft magnetic core before the excitation coil is wound.

[0029] In one embodiment of the present invention, the fluxgate sensor 1 is configured to operate in an open-loop mode; in a variant, a compensation coil may be further wound on the soft magnetic core 14 to achieve a closed-loop operation mode for the fluxgate sensor.

[0030] In one variant, in addition to the excitation coil, a test coil can be wound separately on the soft magnetic core to inject a test current signal, which is well known in the field of fluxgate sensors.

[0031] The fluxgate head 2 has a central channel 20 that allows the main conductor assembly to pass through. The cross-sectional area of ​​the central channel for the main conductor assembly to pass through may be defined by a housing 3, which has a central channel 20a inside the central channel 20 of the fluxgate head.

[0032] The dominant conductor assembly 5 includes multiple dominant conductor layers 6, including at least one electrical phase dominant conductor layer. In a single-phase power system, a second dominant conductor layer, i.e., a return conductor or a neutral conductor, is also present. For a multiphase power system with a multiphase dominant conductor assembly, the dominant conductor layers include one dominant conductor layer for each phase, and optionally an additional dominant conductor layer for the neutral phase. It should be noted that in a multiphase system, for the purpose of measuring residual current, it is not mandatory for the neutral phase in the dominant conductor assembly to be located in the central channel passing through the fluxgate sensor. This is because, in the absence of leakage or other forms of residual current, the sum of the currents in each phase of a multiphase system should be zero. Nevertheless, it is still preferable to have the neutral conductor as the dominant conductor layer passing through the central channel of the fluxgate head 2.

[0033] According to one aspect of the invention, a main body assembly 5 is formed on a circuit board 4 extending from a first surface mount connection edge 10 to a second surface mount connection edge 11 and penetrating the central channel 20 of the fluxgate head 2. The first surface mount connection edge 10 is located outside the central channel on one side of the fluxgate head, the second surface mount connection edge 11 is located outside the central channel on the other side of the fluxgate head, and the middle portion of the main body assembly is located within the central channel 20 of the fluxgate head, thereby being surrounded by the soft magnetic core 18 and the excitation coil 16.

[0034] Each dominant layer includes conductive traces, typically metallized conductive traces, and adjacent dominant layers are separated by insulating layers. Dominant layers 6a, 6b, 6c, and 6d can be fabricated as conductive traces on different layers of a circuit board using multilayer circuit board manufacturing processes known in the art, with each conductive trace separated by an insulating layer. However, other variations can be employed without departing from the scope of the invention: for example, stacking separately fabricated conductive and insulating foils, stacking insulating foils with metal lines, or using various other known processes to form a stacked insulating and conductive layer structure. In these manufacturing variations, the term "circuit board" does not specifically refer to printed circuit board technology, but rather to the aforementioned types of flat substrates that can be fabricated with stacked dominant components, which can subsequently be connected to external circuit boards of electronic systems.

[0035] Each dominant layer includes a first connection pad 7, a center portion 9, and a second connection pad 8. The center portion 9 connects the first connection pad and the second connection pad to each other, wherein the first connection pad 7 is located at the first surface mount connection edge 10 of the circuit board 4, and the second connection pad 8 is located at the second surface mount connection edge 11. The first connection pad 7 and the second connection pad 8 are configured to be directly connected to corresponding conductive pads or conductive traces on the external circuit board 101 via surface mount technology. These conductive traces are... Figure 2a and Figure 2bThe conductive trace 102 is shown in the diagram. Therefore, the fluxgate current sensor is configured to be surface-mount connected to the external circuit board 101 via a conventional surface-mount connection method known to those skilled in the art.

[0036] However, it should be noted that in some variations, the first and second connection pads may have various configurations, such as allowing pluggable connections to a receptacle connector, whose receptacle contacts abut against the corresponding connection pads by spring preload. This can be achieved at the first end, the second end, or both ends. For example, one end of a fluxgate sensor may be soldered to a circuit board or flexible circuit with conductive traces, while the other end may be configured for pluggable connection to a receptacle connector. In other variations, both the first connection edge 10 and the second connection edge 11 may be configured for pluggable connections to mating connectors.

[0037] Each of the dominant conductor layers 6a, 6b, 6c, and 6d completely overlaps at its central 9 points, or at least partially overlaps at its central 9 points. This ensures that the magnetic fields generated by each dominant conductor layer 6a, 6b, 6c, and 6d are highly aligned and cancel each other out, thus avoiding the adverse effects of spatial distribution caused by the physical size of the dominant conductors (as is common in conventional systems composed of conductors made of wires). The overlapping relationship between the dominant conductor layers also eliminates the need for shielding, as the electric fields generated by the dominant conductors can also be effectively canceled out, and there is almost no effect from uneven spatial distribution.

[0038] The dominant layer preferably includes slots 22 extending into the dominant layer, which extend perpendicularly to the outer edge of the conductor layer extending axially along the central channel 20. The slots 22 provide the dominant layer with a large surface area, which helps dissipate heat generated by the main current flowing through the dominant layer, while also guiding the flow of the main current. These slots ensure that the main current of each phase flows through the central portion 9, which is designed to optimize the overlap and cancellation of the magnetic fields generated by the dominant phases.

[0039] The first connection pad 7 and the second connection pad 8 of each main conductor layer are preferably arranged radially opposite each other, and the connection pads of different conductor layers 6a, 6b, 6c and 6d are staggered, so that the positions of the first connection pad 7 and the second connection pad 8 are distributed along the first surface mount connection edge 10 and the second surface mount connection edge 11 of the circuit board, respectively.

[0040] To configure connection pads for surface mount connections on one or both sides of circuit board 4, conductive vias penetrating all layers of the circuit board are provided between the connection pads of the main body layer and the connection pads for external connections. These conductive vias can be configured in a known manner to interconnect stacked conductor layers within the circuit board.

[0041] The main conductor structure is preferably disposed on a circuit board 4, which can be inserted along the axial direction of the central channels 20, 20a, thereby facilitating the assembly of the fluxgate sensor. The fluxgate head 2 and the housing 3 can also be assembled along the said axial direction. Furthermore, the main conductor assembly 5 is formed on the circuit board 4, and the very flat main conductor structure can be inserted into the low-height central channels 20, 20a and connected to the thinner fluxgate sensor, which is particularly advantageous for integrating it into the circuit board of the external electronic system 100 or onto its surface.

[0042] The external electronic system may include a circuit board 101 having conductive traces 102 for connecting a first connection pad 7 and a second connection pad 8 of the main body assembly 5. The external circuit board 101 preferably has a fluxgate receiving notch 103 into which a portion of the fluxgate 2 can be inserted, thereby minimizing the overall height of the fluxgate sensor.

[0043] The excitation coil 16 and any other coils, such as test coils or compensation coils, can also be connected in various ways to coil connection pads formed on the circuit board 4, which may also be provided with connection pads for surface mount connection to complementary conductive pads or traces 112 on the system circuit board 101.

[0044] Reference List Fluxgate Current Sensor 1 Magnetic flux gate 2 Soft magnetic core 14 Excitation coil 16 Test or compensation coil Coil support housing 18 Core housing cavity 19 Central Passage 20 Casing 3 Base 3a Cover plate 3b Circuit board 4 Main component 5 Dominant body layers 6, 6a, 6b, 6c, 6d First connection pad 7 Second connection pad 8 Central Part 9 Slot 22 First surface mount connection edge 10 Second surface mount connection edge 11 Electronic Systems 100 System Circuit Board 101 Conductive trace 102 Magnetic flux gate receiver cutout 103 Secondary conductor connection pad 112

Claims

1. A fluxgate current sensor (1), comprising a fluxgate head (2) and a main body assembly (5), the fluxgate head comprising a soft magnetic core (14) and an excitation coil (16) wound on the soft magnetic core, the soft magnetic core surrounding a central channel (20, 20a) in the form of an elongated slot, characterized in that, The fluxgate sensor also includes a flat substrate extending through the central channel between a first connecting edge (10) and a second connecting edge (11). The main body assembly includes a plurality of stacked main conductor layers formed on or inside the flat substrate, each main body layer being separated from an adjacent main conductor layer by an insulating layer.

2. The fluxgate current sensor according to claim 1, wherein, The main body assembly includes a first connection terminal (7) disposed along the first connection edge (10) of the substrate and a second connection terminal (8) disposed along the second connection edge (11) of the substrate. The first connection edge is located outside the central channel (20) on one side of the fluxgate (2), and the second connection edge is formed outside the central channel on the second side of the fluxgate in the axial direction.

3. The fluxgate current sensor according to any of the preceding claims, wherein, The substrate is in the form of a circuit board (4), and the main body layer is formed on different layers within the circuit board.

4. The fluxgate current sensor according to any of the preceding claims, wherein, The first connection terminal (7) includes conductive pads arranged along adjacent connection terminals and spaced apart from adjacent connection terminals, the conductive pads being configured for surface mount soldering connection with conductive traces of an external circuit board (101).

5. The fluxgate current sensor according to any of the preceding claims, wherein, The soft magnetic core (14) of the fluxgate is installed in the core receiving cavity (19) of the coil support housing (18), and the excitation coil (16) is wound on the coil support housing (18).

6. The fluxgate current sensor according to any of the preceding claims, wherein, The fluxgate is installed inside the housing (3), which has a central channel (20a) for inserting the substrate forming the main body assembly.

7. The fluxgate current sensor according to any of the preceding claims, wherein, Each of the main conductor layers of the main conductor assembly (5) includes a central portion (9) connecting the first connection terminal and the second connection terminal, wherein the central portions of the plurality of stacked main conductor layers completely overlap each other.

8. The fluxgate current sensor according to any of the preceding claims, wherein, Each of the main body layers includes a groove (22) extending from a side, the side extending axially along the central channel.

9. The fluxgate current sensor according to any of the preceding claims, wherein, The first and second connection terminals of each dominant body layer are arranged radially opposite each other with the centerline extending axially along the central channel as the axis of symmetry.

10. An electronic system (100) comprising a fluxgate current sensor according to any of the preceding claims and a system circuit board (101) having conductive traces (102), the system circuit board further comprising a fluxgate head receiving cutout (103) into which a portion of the fluxgate head (2) is inserted.

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