Direct current filter inductor and electronic device

Abstract

The embodiment of the application provides a DC filtering inductor and electronic equipment, and relates to the technical field of inductors; the DC filtering inductor comprises a PCB circuit board, a coil assembly and a magnetic flux cancellation assembly; the coil assembly comprises a magnetic core, a primary winding and a secondary winding; the primary winding and the secondary winding are both wound on a magnetic column of the magnetic core; the magnetic column is provided with an air gap and is located between two primary coils of the primary winding; a first external connection terminal of the primary winding is arranged on the PCB circuit board; the magnetic flux cancellation assembly comprises a Hall sensor integrated on the PCB circuit board and a differential amplification circuit; a detection end of the Hall sensor is located in the air gap; two ends of the differential amplification circuit are connected with the detection end of the Hall sensor and an input connection end of the secondary coil; a cancellation current output by the differential amplification circuit and a magnetic field generated by the primary winding on the secondary winding are mutually cancelled, so that the cost of the DC inductor can be reduced while the large-current filtering function of the DC filtering inductor is considered.

Description

Technical Field

[0001] This application relates to the field of inductor technology, and more particularly to a DC filter inductor and electronic device. Background Technology

[0002] DC inductors are commonly used for DC filtering. However, when a DC current is applied, the magnetic flux density on the core increases with the current. But due to the BH property of the core material, the inductance of the DC inductor gradually decreases as the magnetic flux density increases. When the current reaches a certain value, the core saturates, and the inductance of the DC inductor drops sharply, leading to the failure of its filtering capability. Therefore, in related technologies, to ensure that the DC filter inductor can carry a larger current, a current transformer is often introduced outside the DC inductor, and the DC inductor and the current transformer are used together. However, this method increases assembly and management costs. Therefore, how to reduce the cost of DC filter inductors while taking into account their high-current filtering function is an urgent technical problem to be solved. Summary of the Invention

[0003] The main objective of this application is to propose a DC filter inductor that can reduce the cost of DC filter inductors while maintaining their high-current filtering function.

[0004] To achieve the above objectives, a first aspect of this application provides a DC filter inductor, comprising: PCB circuit board; A coil assembly is located above the PCB circuit board. The coil assembly includes a magnetic core, a primary winding, and a secondary winding. Both the primary and secondary windings are wound on the magnetic core. An air gap is provided on the magnetic core, and the two primary coils of the primary winding are located on both sides of the air gap. The two primary coils are located between the two secondary coils of the secondary winding. The first external connection terminals of the two primary coils are provided on the PCB circuit board, and the two primary coils are connected in parallel through the PCB circuit board. A flux cancellation component includes a Hall sensor and a differential amplifier circuit. The Hall sensor and the differential amplifier circuit are integrated on the PCB circuit board. The detection end of the Hall sensor is located in the air gap. The input end of the differential amplifier circuit is connected to the detection end of the Hall sensor. The output end of the differential amplifier circuit is connected to the input connection end of the secondary coil. The output connection end of the secondary coil is grounded. The primary winding forms a primary-side current loop through the PCB circuit board. The direction of the cancelling current output by the differential amplifier circuit is opposite to the direction of the current in the primary-side current loop, so that the cancelling current and the magnetic field generated by the primary-side current loop cancel each other out.

[0005] To achieve the above objectives, a second aspect of the embodiments of this application provides an electronic device, such as any of the electronic devices described in the first aspect.

[0006] The DC filter inductor and electronic device proposed in this application form a conventional DC filter inductor by winding two primary coils on a magnetic column with an air gap. A Hall sensor is placed in the air gap between the two primary coils on the magnetic column. The Hall effect occurs when the sensor senses magnetic flux generated by the primary coils, which in turn generates a canceling current opposite to the current in the primary current loop via a differential amplifier circuit. Since the canceling current and the magnetic field generated by the primary current loop cancel each other out, the magnetic circuit of the entire DC filter inductor is kept as close to zero flux as possible. Consequently, the inductance value of the DC filter inductor remains at its initial 0A and does not decrease with increasing current, thus achieving high-current filtering. Furthermore, since the Hall sensor and differential amplifier circuit are directly integrated on the PCB board, and the PCB board is integrated with the primary and secondary windings, the manufacturing of the DC filter inductor is simpler, reducing maintenance and production costs. Therefore, compared with related technologies, the embodiments of this application can reduce the cost of the DC filter inductor while still achieving high-current filtering functionality. Attached Figure Description

[0007] Figure 1 This is a schematic diagram of the structure of one embodiment of the DC filter inductor provided in this application; Figure 2 This is an exploded view of the structure of one embodiment of the DC filter inductor provided in this application; Figure 3 This is a cross-sectional structural schematic diagram of one embodiment of the DC filter inductor provided in this application; Figure 4 This is a schematic diagram of the circuit principle of the DC filter inductor provided in this application.

[0008] Figure label: Coil assembly 100, magnetic core 110, magnetic column 111, first magnetic column 1111, second magnetic column 1112, primary winding 120, primary coil 121, secondary winding 130, secondary coil 131, air gap 140, primary side current 150, magnetic yoke 160, first magnetic yoke 161, second magnetic yoke 162. PCB circuit board 200, support component 210, second external connection terminal 220, Magnetic flux cancellation component 300, Hall sensor 310, differential amplifier circuit 320. Detailed Implementation

[0009] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0010] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. The terminology used herein is for the purpose of describing embodiments of this application only and is not intended to limit this application. The terms “first,” “second,” “third,” “fourth,” etc. (if present) in the specification and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence.

[0011] Furthermore, the described features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. Numerous specific details are provided in the following description to give a thorough understanding of embodiments of this disclosure. However, those skilled in the art will recognize that the technical solutions of this disclosure can be practiced without one or more of the specific details, or other methods, components, apparatuses, steps, etc., can be employed. In other instances, well-known methods, apparatuses, implementations, or operations are not shown or described in detail to avoid obscuring various aspects of this disclosure.

[0012] DC inductors are commonly used for DC filtering. However, when a DC current is applied, the magnetic flux density on the core increases with the current. Due to the BH property of the core material, the inductance gradually decreases as the flux density increases. Once the current reaches a certain value, the core saturates, and the inductance drops sharply, leading to a failure of the filtering capability. Therefore, in related technologies, to ensure that the DC filter inductor can handle larger currents, a current transformer is often introduced externally, and the DC inductor and current transformer are used in conjunction. However, since the current transformer and DC transformer are independent devices, they need to be managed and manufactured separately. Furthermore, the current transformer contains many components, and this loosely coupled connection increases assembly and management costs. Therefore, how to reduce the cost of DC filter inductors while maintaining their high-current filtering function is a pressing technical problem. Based on this, this application proposes a DC filter inductor that can reduce its cost while maintaining its high-current filtering function.

[0013] Reference Figures 1 to 4 As shown, the DC filter inductor provided according to the embodiments of this application includes: PCB circuit board 200; A coil assembly 100 is located above a PCB circuit board 200. The coil assembly 100 includes a magnetic core 110, a primary winding 120, and a secondary winding 130. Both the primary winding 120 and the secondary winding 130 are wound on magnetic posts 111 of the magnetic core 110. An air gap 140 is provided on the magnetic post 111, and the two primary coils 121 of the primary winding 120 are located on both sides of the air gap 140. The two primary coils 121 are located between the two secondary coils 131 of the secondary winding 130. The first external connection terminals of the two primary coils 121 are provided on the PCB circuit board 200, and the two primary coils 121 are connected in parallel through the PCB circuit board 200. The flux cancellation component 300 includes a Hall sensor 310 and a differential amplifier circuit 320. The Hall sensor 310 and the differential amplifier circuit 320 are integrated on the PCB circuit board 200. The detection end of the Hall sensor 310 is located in the air gap 140. The input end of the differential amplifier circuit 320 is connected to the detection end of the Hall sensor 310. The output end of the differential amplifier circuit 320 is connected to the input connection end of the secondary coil 131. The output connection end of the secondary coil 131 is grounded. The primary winding 120 forms a primary current loop through the PCB circuit board 200. The direction of the canceling current output by the differential amplifier circuit 320 is opposite to the direction of the current in the primary current loop, so that the canceling current and the magnetic field generated by the primary current loop cancel each other out.

[0014] A conventional DC filter inductor is formed by winding two primary coils 121 on a magnetic post 111 with an air gap 140 on the magnetic post 111. The detection end of a Hall sensor 310 is placed in the air gap 140 between the two primary coils 121 on the magnetic post 111. The Hall sensor 310 can generate a Hall effect when it senses the magnetic flux generated by the primary coil 121. This generates a canceling current opposite to the current direction of the primary current loop through the differential amplifier circuit 320. Since the canceling current and the magnetic field generated by the primary current loop in the two primary coils 121 cancel each other out, the magnetic circuit of the entire DC filter inductor can be kept as close to zero magnetic flux as possible. Consequently, the inductance value of the DC filter inductor will always be in the initial 0A inductance state and will not decrease as the current increases, thus achieving high current filtering. Meanwhile, since the Hall sensor 310 and the differential amplifier circuit 320 are directly integrated on the PCB board, and the PCB board is integrated with the primary winding 120 and the secondary winding 130, the fabrication of the DC filter inductor is simpler, thereby reducing maintenance and production costs. Therefore, the embodiments of this application can reduce the cost of the DC filter inductor while still maintaining its high-current filtering function.

[0015] The input connection terminal of the secondary coil 131 represents the terminal at which the secondary winding 130 is input, and the output connection terminal of the secondary coil 131 represents the terminal at which the secondary winding 130 is output. Two secondary coils 131 can be connected in series. Taking two secondary coils 131 connected in series as an example, the input connection terminal and the output connection terminal represent the non-series-connected ends of the secondary coils 131, respectively.

[0016] By connecting two primary coils 121 in parallel, the DC filter inductor can achieve current filtering over a wider range.

[0017] The differential amplifier circuit 320 amplifies the small voltage on the Hall element using the principle of a Hall current transformer. Then, a differential comparison is performed, and a reverse current is output to the secondary coil 131. This application embodiment does not limit the type of Hall sensor 310; those skilled in the art can selectively configure it according to the required detection accuracy. This application embodiment does not limit what the flux cancellation component 300 also includes. In some embodiments, the flux cancellation component 300 is further provided with a bias circuit, the output terminal of which is connected to the bias input terminal of the Hall sensor 310. For example, see [reference]. Figure 4 As shown, the bias circuit includes operational amplifier U2, and the non-inverting input of U2 is connected to the bias current I. H The inverting input of U2 is connected to the input pin of Hall sensor 310, and the output of U2 provides a stable DC bias current to Hall sensor 310.

[0018] In some embodiments, the total number of turns of the primary winding 120 may be the same as or different from the total number of turns of the secondary winding 130. This application embodiment does not limit whether the number of turns of the two primary windings 121 is the same; in some embodiments, the two primary windings 121 have the same number of turns. This application embodiment does not limit whether the number of turns of the two secondary windings 131 is the same; in some embodiments, the two secondary windings 131 have the same number of turns. This application embodiment does not limit the size of the air gap 140; those skilled in the art can selectively set it based on the actual inductance and the thickness of the detection end of the Hall sensor 310.

[0019] This application does not limit the shape of the magnetic core 110, nor does it limit whether other circuits are integrated on the PCB circuit board 200.

[0020] In some embodiments, such as Figure 1 and Figure 2 As shown, a conductive line connecting two primary coils 121 is provided on the PCB circuit board 200, thereby enabling the two primary coils 121 to be connected in parallel via the PCB circuit board 200. Higher current filtering can be achieved by connecting the two secondary coils 131 in parallel. The first external connection terminal of the primary coil 121 is a terminal for connecting to an external power supply; in some embodiments, such as... Figure 1 As shown, the two first external connection terminals of the primary coil 121 extend out of the PCB circuit board 200, so that the external power supply can directly supply the primary side current 150 through the first external connection terminals.

[0021] This application does not limit the type of the primary coil 121. In some embodiments, it can be wound with flat wire, while in others, it can be wound with round copper wire. The specific type can be determined based on the magnitude of the primary current 150 that the primary coil 121 is allowed to pass through and the winding space on the magnetic post 111. This application also does not limit the type of the secondary coil 131.

[0022] Reference Figure 3 As shown, in this embodiment of the application, the width of the air gap 140 is at least greater than the thickness of the detection end of the Hall sensor 310, thereby allowing the Hall sensor 310 to perform magnetic flux detection on the primary coil 121.

[0023] Understandably, referring to Figure 4As shown, the differential amplifier circuit 320 includes an operational amplifier, a first transistor, and a second transistor. The collector of the first transistor is connected to a positive power supply, and the collector of the second transistor is connected to a negative power supply. The bases of the first and second transistors are shorted to form a signal input terminal, and the emitters of the first and second transistors are shorted to form a signal output terminal. The output terminal of the operational amplifier is connected to the signal input terminal, and the signal output terminal is connected to the input connection terminal. The two input terminals of the operational amplifier are connected to the detection terminal of the Hall sensor 310.

[0024] A differential circuit structure is formed by the first transistor and the second transistor. At this time, the induced voltage of the Hall sensor 310 is integrated and amplified by the operational amplifier. The amplified voltage is then fed back to the secondary coil 131 through the differential circuit structure (the first transistor and the second transistor). Since the differential circuit structure can provide a suitable current to the secondary coil according to the feedback voltage difference, it can ensure that the canceling current passing through the secondary coil 131 can just cancel the magnetic field generated by the primary current on the primary coil 121, so that the induced voltage of the Hall sensor 310 is infinitely close to 0, and thus the entire magnetic circuit exhibits zero magnetic flux.

[0025] The embodiments of this application do not impose any restrictions on the selection of the first transistor, the second transistor, and the operational amplifier. Those skilled in the art can selectively set them according to actual needs.

[0026] For example, refer to Figure 4 As shown, taking the first transistor as VT1, the second transistor as VT2, and the operational amplifier as U1 as an example, the collector of VT1 is connected to the positive power supply +UC, the collector of VT2 is connected to the negative power supply -UC, the bases of VT2 and VT1 are shorted to form the signal input terminal, the emitters of VT2 and VT1 are shorted to form the signal output terminal, the output terminal of U1 is connected to the signal input terminal, the signal output terminal is connected to the input connection terminal, and the two input terminals of the operational amplifier are connected to the detection terminal of the Hall sensor 310.

[0027] Understandably, referring to Figure 4 As shown, the differential amplifier circuit 320 also includes a first resistor, a second resistor, and a third resistor. The first resistor is connected between the first detection terminal of the Hall sensor 310 and the non-inverting input terminal of the operational amplifier. The second resistor is connected between the second detection terminal of the Hall sensor 310 and the inverting input terminal of the operational amplifier. The first terminal of the third resistor is connected to the input connection terminal, and the second terminal of the third resistor is grounded.

[0028] This application does not limit the resistance values ​​of the first, second, and third resistors, nor does it limit the number of the first, second, and third resistors. Those skilled in the art can selectively set these resistors according to the actual circuit structure and the magnitude of the offset current. Therefore, this application will not elaborate on these details.

[0029] For example, refer to Figure 4 As shown, the first resistor is R0, the second resistor is R2, and the third resistor is R1, and one of each is provided. The two ends of R0 are connected to the first detection terminal of the Hall sensor 310 and the non-inverting input terminal of the operational amplifier, respectively; the two ends of R2 are connected to the second detection terminal of the Hall sensor 310 and the inverting input terminal of the operational amplifier, respectively; and the two ends of R3 are connected to the input connection terminal and ground, respectively.

[0030] Understandably, referring to Figure 2 As shown, the magnetic core 110 has a magnetic yoke 160 including a first magnetic yoke 161 and a second magnetic yoke 162. The first magnetic yoke 161 and the second magnetic yoke 162 enclose a hollow cavity with open sides on opposite sides. The magnetic column 111 is disposed in the hollow cavity, and the PCB circuit board 200 is located below the opening side of the hollow cavity.

[0031] The magnetic core 110 consists of a yoke 160 and a magnetic post 111. In some embodiments, refer to Figure 2 As shown, the magnetic pillar 111 includes a first magnetic pillar 1111 and a second magnetic pillar 1112. The first magnetic pillar 1111 is integrally formed with the first magnetic yoke 161, and the second magnetic pillar 1112 and the second magnetic yoke 162 are integrally formed.

[0032] In some embodiments, the opposite sides of the first magnetic yoke 161 and the second magnetic yoke 162 abut against each other to form a hollow cavity with through sides, thereby improving the convenience of coil winding and Hall sensor 310 assembly through two independent magnetic yokes 160.

[0033] In some embodiments, the outer contour of the PCB circuit board 200 is smaller than the outer contour dimension of the hollow cavity formed by the first magnetic yoke 161 and the second magnetic yoke 162.

[0034] Understandably, referring to Figure 1 and Figure 2 As shown, a plurality of support members 210 are provided on the PCB circuit board 200, and the plurality of support members 210 are used to support the first magnetic yoke 161 and the second magnetic yoke 162.

[0035] This application embodiment does not limit the number of support members 210, nor does it limit how the support members 210 are distributed, nor does it limit the support height of the support members 210, nor does it limit the material of the support members 210. Those skilled in the art can selectively set the support members 210 according to the weight of the magnetic core 110, the direction of the magnetic circuit, and the width of the magnetic core 110.

[0036] For example, refer to Figure 2As shown, multiple support members 210 are distributed on two opposite sides of the PCB circuit board 200, located on the side where the magnetic post 111 connects to the magnetic yoke 160. At least three support members 210 are distributed on each side, and at least two support members 210 are located at the corners of the PCB circuit board 200. In some embodiments, the support member 210 is block-shaped, with its upper surface abutting against the lower surface of the magnetic yoke 160. In some embodiments, the support member 210 is a plastic block. In other embodiments, the support member 210 may also be made of other non-conductive materials. The support member 210 may also be of other shapes.

[0037] Therefore, by setting multiple support members 210, the PCB circuit board 200 and the magnetic core 110 can be more stably combined together, while ensuring that the magnetic core 110 and the PCB circuit board 200 are at least a preset distance apart, so as to reduce the impact of the magnetic field generated by the primary coil 121 on the electronic components in the PCB circuit board 200 when energized.

[0038] Understandably, referring to Figure 4 As shown, the DC filter inductor also includes a sampling resistor, which is integrated on the PCB circuit board 200. The first end of the sampling resistor is connected to the output connection terminal of the secondary coil 131, and the second end of the sampling resistor is grounded. The sampling resistor is used to connect to the current detection circuit so that the current detection circuit can determine the primary side current of the primary winding based on the voltage across the sampling resistor.

[0039] By setting a sampling resistor, it is possible to predict the magnitude of the current in the primary side current loop through which the primary coil 121 flows.

[0040] This application does not limit the structure of the current detection circuit. In some embodiments, a voltage acquisition circuit can be integrated on the PCB board to sample the voltage of the sampling resistor, thereby determining the current passing through the secondary winding 130 based on the sampled voltage. In this case, using the ampere-turn balance principle Np*Ip=Ns*Is, and given that the number of turns in the secondary winding 130 and the primary winding 120 are known, the magnitude of the current in the primary current loop can be determined. In other embodiments, an external integrated chip can also be used to sample the resistor; however, this application will not elaborate on these specific examples.

[0041] This application does not limit what operation to be performed after determining the magnitude of the primary current 150 in the primary current loop based on the sampling resistor. In some embodiments, current warning can be performed, and in other embodiments, the trend of current change can be recorded for fault location. This application will not elaborate on these aspects. For example, refer to Figure 4As shown, the sampling resistor is set to RL, and its two ends are connected to the output terminal of the secondary coil 131 and ground, respectively. The end of RL furthest from the secondary coil 131 is connected to the signal output terminal through R1.

[0042] Understandably, the current detection circuit includes a detection chip integrated on the PCB circuit board 200. The detection chip is configured to determine the primary side current 150 of the primary winding 120 based on the sampling voltage of the sampling resistor, the number of turns of the first coil of the secondary winding 130, and the number of turns of the second coil of the primary winding 120.

[0043] With the sampling resistor known, the total current of the secondary winding 130 can be determined based on the sampling voltage. Then, according to the ampere-turn balance principle Np*Ip=Ns*Is, the primary current passing through the primary winding 120 can be determined.

[0044] The detection chip can be an integrated chip. This application does not limit the type of detection chip, and those skilled in the art can selectively set it according to actual needs. Integrating the detection chip into the PCB circuit board 200 can simplify the structure of the DC filter inductor, making the overall size of the DC filter inductor more concentrated and smaller, and thus applicable to more electronic devices.

[0045] Understandably, a plurality of second external connection terminals 220 are provided on the side of the PCB circuit board 200 away from the coil assembly 100, and the plurality of second external connection terminals 220 are used to connect to an external power supply.

[0046] By placing all the second external connection terminals 220 on one side, the connection between the PCB circuit board 200 and an external power supply can be facilitated. This embodiment does not limit the number of second external connection terminals 220; those skilled in the art can selectively set them according to actual needs. Voltage can be supplied to the differential amplifier circuit 320 through the second external connection terminals 220; however, this embodiment will not elaborate on this aspect.

[0047] Understandably, the number of turns and air gap length of the primary winding 120 are determined based on the pre-configured current range, the desired inductance value, and the magnetic permeability parameters of the core 110. The wire diameter of the secondary winding 130 and the wire diameter of the primary winding 120 are determined based on the number of turns and the magnitude of the primary current 150, given that their respective number of turns are determined.

[0048] The current range indicates the magnitude of the current supported by the DC filter inductor in this embodiment of the application, and the desired inductance value indicates the inductance value designed to meet the filtering performance within this current range. The air gap length indicates the distance between the first magnetic post 1111 and the second magnetic post 1112.

[0049] The magnetic permeability parameters include the effective cross-sectional area, effective magnetic path length, initial permeability, and vacuum permeability of the magnetic core 110. Based on the initial permeability, effective magnetic path length, and air gap length, the effective permeability can be determined. Then, based on the effective permeability, vacuum permeability, effective cross-sectional area, effective magnetic path length, and desired inductance value, the number of coil turns in the primary winding 120 can be calculated.

[0050] In some embodiments, the dimensions of the magnetic core 110 can be determined first, thereby determining the effective cross-sectional area and effective magnetic circuit length of the magnetic core 110. Then, the inductance value can be determined using the formula L = ... By adjusting the air gap length and the number of coil turns, a combination of air gap length and coil turns that meets the desired inductance value can be obtained. Where, Ue = Ae represents the effective cross-sectional area; Le represents the effective magnetic path length; Lg represents the air gap length; Ue represents the effective permeability; Ui represents the initial permeability; U0 represents the free permeability; and N represents the total number of turns of the primary coil 121 (i.e., the number of turns of the primary winding 120). At this point, for the primary winding 120, given a fixed number of turns, the wire diameter can be determined based on the current range. Correspondingly, according to the ampere-turn balance principle Np*Ip=Ns*Is, given a fixed number of turns and wire diameter for the primary winding 120, the number of turns and wire diameter for the secondary winding 130 can be determined.

[0051] It is understood that the electronic device provided according to the embodiments of this application includes the electronic device of any of the above embodiments.

[0052] This application does not limit the type of electronic device, such as terminal devices, routing devices, etc.

[0053] The system architecture and application scenarios described in this application are intended to more clearly illustrate the technical solutions of this application and do not constitute a limitation on the technical solutions provided in this application. Those skilled in the art will understand that as system architectures evolve and new application scenarios emerge, the technical solutions provided in this application are also applicable to similar technical problems.

[0054] The above description, with reference to the accompanying drawings, illustrates some embodiments of this application, but does not limit the scope of the invention. Any modifications, equivalent substitutions, and improvements made by those skilled in the art without departing from the scope and spirit of this invention should be considered within the scope of this application.

Claims

1. A DC filter inductor, characterized in that, The DC filter inductor includes: PCB circuit board; A coil assembly is located above the PCB circuit board. The coil assembly includes a magnetic core, a primary winding, and a secondary winding. Both the primary and secondary windings are wound on the magnetic core. An air gap is provided on the magnetic core, and the two primary coils of the primary winding are located on both sides of the air gap. The two primary coils are located between the two secondary coils of the secondary winding. The first external connection terminals of the two primary coils are provided on the PCB circuit board, and the two primary coils are connected in parallel through the PCB circuit board. A flux cancellation component includes a Hall sensor and a differential amplifier circuit. The Hall sensor and the differential amplifier circuit are integrated on the PCB circuit board. The detection end of the Hall sensor is located in the air gap. The input end of the differential amplifier circuit is connected to the detection end of the Hall sensor. The output end of the differential amplifier circuit is connected to the input connection end of the secondary coil. The output connection end of the secondary coil is grounded. The primary winding forms a primary-side current loop through the PCB circuit board. The direction of the cancelling current output by the differential amplifier circuit is opposite to the direction of the current in the primary-side current loop, so that the cancelling current and the magnetic field generated by the primary-side current loop cancel each other out.

2. The DC filter inductor according to claim 1, characterized in that, The differential amplifier circuit includes an operational amplifier, a first transistor, and a second transistor. The collector of the first transistor is connected to a positive power supply, and the collector of the second transistor is connected to a negative power supply. The bases of the first and second transistors are shorted to form a signal input terminal, and the emitters of the first and second transistors are shorted to form a signal output terminal. The output terminal of the operational amplifier is connected to the signal input terminal, and the signal output terminal is connected to the input connection terminal. The two input terminals of the operational amplifier are connected to the detection terminal of the Hall sensor.

3. The DC filter inductor according to claim 2, characterized in that, The differential amplifier circuit further includes a first resistor, a second resistor, and a third resistor. The first resistor is connected between the first detection terminal of the Hall sensor and the non-inverting input terminal of the operational amplifier. The second resistor is connected between the second detection terminal of the Hall sensor and the inverting input terminal of the operational amplifier. The first terminal of the third resistor is connected to the input connection terminal, and the second terminal of the third resistor is grounded.

4. The DC filter inductor according to claim 1, characterized in that, The magnetic core's yoke includes a first yoke and a second yoke, which together form a hollow cavity with open sides. The magnetic pillar is disposed within the hollow cavity, and the PCB circuit board is located below the opening side of the hollow cavity.

5. The DC filter inductor according to claim 4, characterized in that, The PCB circuit board is provided with multiple support members, which are used to support the first magnetic yoke and the second magnetic yoke.

6. The DC filter inductor according to claim 1, characterized in that, The DC filter inductor also includes a sampling resistor, which is integrated on the PCB circuit board. The first end of the sampling resistor is connected to the output connection terminal of the secondary coil, and the second end of the sampling resistor is grounded. The sampling resistor is used to connect to a current detection circuit so that the current detection circuit can determine the primary side current of the primary winding based on the voltage across the sampling resistor.

7. The DC filter inductor according to claim 6, characterized in that, The current detection circuit includes a detection chip integrated on the PCB circuit board. The detection chip is configured to determine the primary side current of the primary winding based on the sampling voltage of the sampling resistor, the number of turns of the first coil of the secondary winding, and the number of turns of the second coil of the primary winding.

8. The DC filter inductor according to claim 1, characterized in that, The PCB circuit board has a plurality of second external connection terminals on the side away from the coil assembly, which are used to connect to an external power supply.

9. The DC filter inductor according to claim 1, characterized in that, The number of turns and air gap length of the primary winding are determined based on the pre-configured current range, desired inductance value, and magnetic core permeability parameters. The wire diameter of the secondary winding and the primary winding are determined based on the number of turns and the magnitude of the primary current, given their respective coil turns.

10. An electronic device, characterized in that, Includes the electronic device as described in any one of claims 1 to 9.

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