CN117665360A

CN117665360A - Closed loop current sensor

Info

Publication number: CN117665360A
Application number: CN202410094147.5A
Authority: CN
Inventors: 王雄星
Original assignee: Shanghai Xinggan Semiconductor Co ltd
Current assignee: Shanghai Xinggan Semiconductor Co ltd
Priority date: 2024-01-23
Filing date: 2024-01-23
Publication date: 2024-03-08

Abstract

The invention discloses a closed loop current sensor, comprising: a U-shaped magnetic core; a planar coil surrounding the U-shaped magnetic core; the Hall chip is used for inducing the change of a magnetic field in the U-shaped magnetic core to form a voltage signal, the signal modulation chip is respectively and electrically connected with the Hall chip and the planar coil, and the signal modulation chip is used for amplifying the voltage signal output by the Hall chip and outputting a current signal; the planar coil is used for compensating the magnetic field in the U-shaped magnetic core according to the current signal. The invention can reduce the volume of the closed-loop current sensor and improve the measurement accuracy of the closed-loop current sensor.

Description

Closed loop current sensor

Technical Field

The invention relates to the technical field of power semiconductors, in particular to a closed loop current sensor.

Background

The sensor is a detecting device, which can detect the relative information of the detected equipment, and convert the relative information into an electric signal or other information output in a required form according to a certain rule so as to meet the requirements of information transmission, processing, storage, display, recording, control and the like.

The existing closed-loop current sensor is more stable than the open-loop current sensor because the compensation coil is provided for secondary side compensation. However, the existing closed-loop current sensor is limited by the magnetic core and the compensation coil structure, and has the problem of low measurement accuracy.

Disclosure of Invention

The invention provides a closed-loop current sensor, which can improve the measurement accuracy of the closed-loop current sensor.

The embodiment of the invention provides a closed loop current sensor, which comprises: a U-shaped magnetic core; a planar coil surrounding the U-shaped magnetic core; the Hall chip is used for inducing the change of a magnetic field in the U-shaped magnetic core to form a voltage signal, the signal modulation chip is respectively and electrically connected with the Hall chip and the planar coil, and the signal modulation chip is used for amplifying the voltage signal output by the Hall chip and outputting a current signal; the planar coil is used for compensating the magnetic field in the U-shaped magnetic core according to the current signal.

Optionally, the U-shaped magnetic core includes a first T-shaped magnetic core body, a second T-shaped magnetic core body, and a curved portion; the first T-shaped magnetic core body and the second T-shaped magnetic core body are oppositely arranged, and the first T-shaped magnetic core body and the second T-shaped magnetic core body are connected through a bending part to form a U-shaped magnetic core.

Optionally, the closed loop current sensor further comprises a PCB board, and the U-shaped magnetic core is plugged on the PCB board from one side of the PCB board.

Optionally, the PCB board includes a groove, and the bending portion is at least partially disposed in the groove.

Optionally, the hall chip and the signal modulation chip are both arranged on one side of the PCB; the vertical projection of the Hall chip on the PCB is at least partially overlapped with the vertical projections of the first T-shaped magnetic core body and the second T-shaped magnetic core body on the PCB.

Optionally, the planar coil includes the coil body and first pin and the second pin of being drawn forth by the coil body, and the PCB board includes first pad and second pad, and first pad and second pad set up in the opposite side of PCB board, and when U-shaped magnetic core pegged graft on the PCB board, first pin and first pad dress, second pin and second pad dress.

Optionally, the planar coil includes the coil body and first pin and the second pin of being drawn forth by the coil body, and the PCB board includes first pad and second pad, and first pad and second pad set up in one side of PCB board, and when U-shaped magnetic core pegged graft on the PCB board, first pin passes through first wire with first pad and is connected, and second pin passes through the second wire with the second pad and is connected.

Optionally, the closed loop current sensor further comprises a sampling unit and a plurality of external pins; the first end of the sampling unit is connected with the signal modulation chip, the second end of the sampling unit is connected with the planar coil, and the sampling unit is used for outputting a current signal according to a voltage signal provided by the signal modulation chip; the external pins are soldered on the PCB board.

Alternatively, the hall chip comprises a gallium arsenide hall chip or an indium antimonide hall chip.

Optionally, the material of the U-shaped magnetic core is nanocrystalline soft magnetic material.

The closed loop current sensor provided by the embodiment of the invention has the advantages that the resistance value of the planar coil is small, the heating value is low, the loss is low, the measurement precision of the current sensor can be improved, and meanwhile, a primary side wire is not required to be arranged, so that the structure of the closed loop current sensor can be simplified, the whole volume of the closed loop current sensor is further reduced, a Hall chip and a signal modulation chip are integrated, peripheral circuit devices are reduced, and the design time of a user and the cost of raw materials are saved.

It should be understood that the description in this section is not intended to identify key or critical features of the embodiments of the invention or to delineate the scope of the invention. Other features of the present invention will become apparent from the description that follows.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for the description of the embodiments will be briefly described below, and it is apparent that the drawings in the following description are only some embodiments of the present invention, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a circuit block diagram of a closed loop current sensor provided by an embodiment of the present invention;

FIG. 2 is a schematic view of a 3D structure of a U-shaped magnetic core and a planar coil according to an embodiment of the present invention;

FIG. 3 is a schematic cross-sectional view of FIG. 2;

FIG. 4 is a schematic diagram of a closed loop current sensor according to the present invention;

FIG. 5 is an exploded view of the structure of FIG. 4;

FIG. 6 is a schematic cross-sectional view of FIG. 4;

fig. 7 is a schematic structural diagram of the front surface of a PCB board according to an embodiment of the present invention;

fig. 8 is a schematic structural diagram of the back surface of a PCB board according to an embodiment of the present invention;

FIG. 9 is a schematic diagram of yet another closed loop current sensor provided by the present invention;

FIG. 10 is a graph showing the magnetic permeability of a nanocrystalline core and ferrite core according to the embodiment of the present invention;

FIG. 11 is a graph showing the magnetic field strength of a nanocrystalline core and ferrite core according to the present invention;

FIG. 12 is a graph showing the temperature variation of the loss of a nanocrystalline core and ferrite core provided by an embodiment of the present invention;

FIG. 13 is a product appearance diagram of a closed loop current sensor of the present invention;

fig. 14 is a front view of fig. 13;

FIG. 15 is a top view of FIG. 13;

FIG. 16 is a side view of FIG. 13;

FIG. 17 is a product appearance diagram of yet another closed loop current sensor of the present invention;

fig. 18 is a product appearance view of still another closed loop current sensor of the present invention.

Detailed Description

In order that those skilled in the art will better understand the present invention, a technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in which it is apparent that the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the present invention without making any inventive effort, shall fall within the scope of the present invention.

It should be noted that the terms "first," "second," and the like in the description and the claims of the present invention and the above figures are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used may be interchanged where appropriate such that the embodiments of the invention described herein may be implemented in sequences other than those illustrated or otherwise described herein. Furthermore, the terms "comprise" and "have," as well as any variations thereof, are intended to cover a non-exclusive inclusion.

Fig. 1 is a circuit structure diagram of a closed loop current sensor according to an embodiment of the present invention, fig. 2 is a 3D structure diagram of a U-shaped magnetic core and a planar coil according to an embodiment of the present invention, fig. 3 is a cross-sectional structure diagram of fig. 2, and in combination with fig. 1, fig. 2 and fig. 3, the closed loop current sensor includes:

a U-shaped magnetic core 11;

a planar coil 12, the planar coil 12 surrounding the U-shaped magnetic core 11;

the Hall chip 13 is used for sensing the change of the magnetic field in the U-shaped magnetic core 11 to form a voltage signal, the signal modulation chip 14 is respectively and electrically connected with the Hall chip 13 and the planar coil 12, and the signal modulation chip 14 is used for amplifying the voltage signal output by the Hall chip 13 and outputting a current signal; the planar coil 12 is used to compensate the magnetic field in the U-shaped core 11 in dependence of the current signal.

Specifically, the U-shaped magnetic core 11 is used for converting a current signal to be measured into a magnetic signal. The planar coil 12 may comprise a multi-turn coil that may be etched on a conductive material by a microelectromechanical casting (Micro-Electro-Me chanical System, MEMS) process. In some embodiments, the planar coil 12 may employ a multi-layer coil arrangement, and the number of turns of the different layers of coils may be the same or different. The outside of the U-shaped magnetic core 11 and the planar coil 12 can be wrapped by silicon dioxide materials, and can be isolated from the outside in an insulating way, so that high-voltage isolation can be realized.

The hall chip 13 may be composed of a hall element for converting a magnetic signal into an electric signal by using a hall principle, and a signal processing circuit for processing the converted electric signal into a voltage signal that can be directly used. The voltage signal is linear with the magnitude of the current on the primary conductor 1, and therefore the magnitude of the current on the primary conductor 1 can be detected from the voltage signal. The hall chip 13 includes, for example, a gallium arsenide hall chip or an indium antimonide hall chip.

Since the voltage signal output from the hall chip 13 is very small, it is typically several microvolts to several hundred microvolts. The signal modulation chip 14 can amplify the voltage signal output by the hall chip 13 to a volt level and output a current signal, and the current signal generates a magnetic field with the same size and opposite direction to the magnetic field after passing through the planar coil 12, so that the magnetic induction intensity in the U-shaped magnetic core 11 is kept to be zero, and the size of the current to be measured can be determined according to the current signal output by the signal modulation chip 14. The signal modulation chip 14 may be various chips having a voltage amplifying function. The signal modulation chip 14 may be an SC241, for example.

Further, the signal modulation chip 14 may also provide excitation for the hall chip 13. The signal modulation chip 14 can be internally provided with a low-offset operational amplifier circuit for eliminating the temperature drift and low-frequency current noise interference of the Hall sensor, thereby improving the precision and the linearity of the closed-loop current sensor.

With continued reference to fig. 1, the closed loop current sensor operates as follows:

during measurement, the primary side wire 1 is internally provided with current to be measured, the magnetic field generated by the current to be measured is gathered in the U-shaped magnetic core 11 according to the electromagnetic induction principle, the Hall chip 13 arranged in the air gap of the U-shaped magnetic core 11 senses the magnetic field to convert a magnetic signal into a voltage signal, the voltage signal is input into the signal modulation chip 14, the signal modulation chip 14 is used for amplifying the voltage signal output by the Hall chip 13 and outputting a current signal, after the current signal passes through the planar coil 12, a second magnetic field (namely, the second magnetic field is a magnetic field generated by the planar coil 12 according to a current signal output by the signal modulation chip 14) with the same size and opposite direction as the first magnetic field (the magnetic field generated by the U-shaped magnetic core 11 according to the current to be measured) is generated, so that the magnetic induction intensity in the U-shaped magnetic core 11 is kept to be zero, the magnetic field in the U-shaped magnetic core 11 can be compensated through the arrangement of the planar coil 12, the influence of the magnetic field on the current to be measured is avoided, and the accuracy of the current to be measured is ensured.

It should be noted that, the closed-loop current sensor of the present invention does not include the primary side wire 1, and the primary side wire 1 may be disposed at any position near the closed-loop current sensor of the present invention by a user according to actual needs, as long as the U-shaped magnetic core 11 can sense the change of the current to be measured in the primary side wire 1, that is, the closed-loop current sensor of the embodiment of the present invention does not need to introduce a large current into the package, so the external pin definition does not need to have a large current introduction pin.

With continued reference to fig. 2 and 3, the u-shaped magnetic core 11 includes a first T-shaped magnetic core body 111, a second T-shaped magnetic core body 112, and a bent portion 113; the first T-shaped magnetic core body 111 and the second T-shaped magnetic core body 112 are disposed opposite to each other, and the first T-shaped magnetic core body 111 and the second T-shaped magnetic core body 112 are connected by a bent portion 113 to form the U-shaped magnetic core 11. Combining the first T-shaped magnetic core body 111, the second T-shaped magnetic core body 112, and the bent portion 113 to form the U-shaped magnetic core 11 can improve the stability of the U-shaped magnetic core 11.

Fig. 4 is a schematic structural view of a closed-loop current sensor according to the present invention, fig. 5 is an exploded structural view of fig. 4, fig. 6 is a schematic sectional structural view of fig. 4, and, in combination with fig. 4, fig. 5 and fig. 6, the closed-loop current sensor further includes a PCB board 20 according to the above technical solution; the U-shaped magnetic core 11 is inserted on the PCB 20 from one side of the PCB 20. As an alternative implementation provided in this embodiment, the PCB 20 includes the groove 30, and the bending portion 113 is at least partially disposed in the groove 30, so that the volume of the closed loop current sensor can be further reduced.

In some embodiments, PCB 20 is 10.1mm long, 8.0mm wide, and 0.25mm thick. The material of the PCB 20 may be rogers board material, or a low cost phenolic FR4 PCB may be used.

With continued reference to fig. 4, the hall chip 13 and the signal modulation chip 14 are both disposed on one side of the PCB board 20; the perpendicular projection of the hall chip 13 on the PCB board 20 at least partially overlaps with the perpendicular projections of the first T-shaped magnetic core body 111 and the second T-shaped magnetic core body 112 on the PCB board 20.

Specifically, the first T-shaped magnetic core 111 includes a first portion and a second portion, and the second T-shaped magnetic core 112 includes a third portion and a fourth portion; the first portion is perpendicular to the second portion, the third portion is perpendicular to the fourth portion, and the first portion is parallel to the third portion, and the second portion is parallel to the fourth portion.

The perpendicular projection of the first portion of the first T-shaped magnetic core 111 onto the PCB board 20 at least partially overlaps with the perpendicular projection of the hall chip 13 onto the PCB board 20 to reduce measurement errors of the hall chip 13.

With continued reference to fig. 4, the closed loop current sensor further includes a sampling unit 15 and a plurality of external pins 16; the first end of the sampling unit 15 is connected with the signal modulation chip 14, the second end of the sampling unit 15 is connected with the planar coil 12, and the sampling unit 15 is used for collecting current signals provided by the signal modulation chip 14; the external leads 16 are soldered to the PCB board 20.

Alternatively, the sampling unit 15 may include at least two resistors, and may also include one resistor, where the at least two resistors are connected in parallel when the sampling unit 15 includes at least two resistors, so as to improve the sampling accuracy of the sampling unit 15.

Fig. 7 is a schematic structural diagram of the front surface of a PCB according to an embodiment of the present invention, and fig. 8 is a schematic structural diagram of the back surface of a PCB according to an embodiment of the present invention. Referring to fig. 5, 7 and 8, the planar coil 12 includes a coil body, first and second pins 17 and 18 led out from the coil body, and the pcb includes first and second pads 201 and 202; the first bonding pad 201 and the second bonding pad 202 are arranged on the other side of the PCB 20, and when the U-shaped magnetic core 11 is plugged on the PCB 20, the first pin 17 is attached to the first bonding pad 201, and the second pin 18 is attached to the second bonding pad 202. That is, the U-shaped core 11 and the planar coil 12 are packaged together with the PCB board 20 by a surface mount technology (Surface Mounted Technology, SMT).

It will be appreciated that the hall chip 13, the signal modulation chip 14 and the sampling unit 15 are all disposed on the front surface of the PCB 20, and the first bonding pad 201 and the second bonding pad 202 are all disposed on the back surface of the PCB.

Fig. 9 is a schematic structural diagram of still another closed loop current sensor provided by the present invention, and in combination with fig. 8 and fig. 9, alternatively, the hall chip 13 and the signal modulation chip 14 are both disposed on one side of the PCB board 20; the perpendicular projection of the hall chip 13 on the PCB board 20 at least partially overlaps with the perpendicular projections of the first T-shaped magnetic core body 111 and the second T-shaped magnetic core body 112 on the PCB board 20.

The planar coil 12 comprises a coil body, a first pin 17 and a second pin 18 led out from the coil body, and the PCB 20 comprises a first bonding pad 201 and a second bonding pad 202; the first bonding pad 201 and the second bonding pad 202 are arranged on one side of the PCB 20, and when the U-shaped magnetic core 11 is plugged on the PCB 20, the first pin 17 is connected with the first bonding pad 201 through a first wire, and the second pin 18 is connected with the second bonding pad 202 through a second wire.

In some embodiments, the material of the U-shaped magnetic core 11 is nanocrystalline soft magnetic material. Fig. 10 is a graph showing the magnetic permeability of a nanocrystalline magnetic core and a ferrite magnetic core according to an embodiment of the present invention, fig. 11 is a graph showing the magnetic field strength of a nanocrystalline magnetic core and a ferrite magnetic core according to an embodiment of the present invention, and fig. 12 is a graph showing the loss of a nanocrystalline magnetic core and a ferrite magnetic core according to an embodiment of the present invention.

Wherein the magnetic field H is a parameter describing the strength of the magnetic field, in milliamperes per centimeter (mA/cm), and the magnetization B is a parameter describing the strength of the magnetic field to produce an induced magnetic moment, in millitesla (mT). The magnetic permeability mu is a physical quantity representing magnetism of the magnetic medium, the magnetic permeability mu is equal to the ratio of magnetic induction intensity B to magnetic field intensity H in the magnetic medium, the unit of iron loss is W/kg (watts/kilogram), and the unit of temperature t is (degrees centigrade).

In this example, comparison of characteristics of VITROPERM 5OOF nanocrystalline core material and Siemens N67 series ferrite core of VAC, germany is illustrated: as can be seen from fig. 10, 11 and 12, the magnetic permeability μ of the nanocrystalline core varies much less with temperature t than the ferrite core, and the stability and reliability of the current sensor can be improved.

The magnetic field H of the nanocrystalline core is many times higher than that of the ferrite core, meaning that the closed loop current sensor can be reduced in volume and weight, and the core is smaller and lighter. When the temperature changes, the loss of the nanocrystalline magnetic core is far lower than that of the ferrite magnetic core, the Curie point temperature of the ferrite magnetic core is lower, and the ferrite magnetic core is easy to demagnetize at high temperature and cannot work. The nanocrystalline soft magnetic material also has high magnetic permeability, the static initial magnetic permeability is more than 10 times of that of ferrite, the excitation power is reduced, and the induction efficiency of the coil is improved. The ferrite magnetic ring material has low saturation current, when the current exceeds the saturation current, the magnetic permeability can be rapidly reduced, and the internal inductance can be rapidly reduced at the same time, so that the existing closed-loop current sensor can not accurately measure the application requirement of the current exceeding 150A. By adopting the nanocrystalline material and the planar coil and matching with the Hall chip and the signal modulation chip, the invention can realize the 0A-2000A current measurement application, and can realize the 0.5% accuracy of current detection in 0A-2000A. Compared with the traditional closed-loop current sensor, the volume is reduced, the heating power consumption is reduced, the automatic SMT assembly can be realized by using semiconductor equipment, unmanned assembly operation is realized, the welding reliability is high, the consistency and stability of products are ensured, the automatic paster production can be realized by the finished product, the reliability requirement of AEC-Q100 Grade1 vehicle gauge is met, the working can be carried out within the temperature range of-40 to +150 ℃, and the high-precision current detection is executed.

Fig. 13 is a product appearance view of a closed loop current sensor of the present invention, fig. 14 is a front view of fig. 13, fig. 15 is a top view of fig. 13, and fig. 16 is a side view of fig. 13.

Referring to fig. 13, 14, 15 and 16, the closed loop current sensor includes a plurality of external pins 16, the plurality of external pins 16 including a power supply pin VCC, a ground pin GND, an output pin VOUT, a communication pin RE-SEL2, and a programming pin PROG

It should be noted that the closed-loop current sensor may be made into another external appearance, fig. 17 is a product external appearance diagram of another closed-loop current sensor according to the present invention, and fig. 18 is a product external appearance diagram of another closed-loop current sensor according to the present invention.

The embodiment of the invention also provides a production process flow of the closed-loop current sensor, which comprises the following steps:

s1, PCB processing: the PCB incoming material is pretreated, and no obvious appearance problems such as oxidization, cracking, burrs, plating leakage and the like are confirmed.

S2, cleaning the PCB: ultrasonic water washing is used to remove dirt and foreign matters on the surface of the PCB and ensure the cleanness of PCB mounting.

S3, thinning the wafer: the whole hall wafer is thinned to a required thickness. An exemplary thickness reduction from 725um to 200 um.

S4, wafer dicing: the thinned Hall wafer is cut into single small chips, so that the follow-up chip loading and picking are facilitated.

S5, loading: and the Hall chip, the signal modulation chip and the sampling unit are arranged on the PCB.

S6, baking after chip loading: the procedure can be realized by heating and curing the die attach glue at the temperature of the oven, so that the Hall chip can be firmly adhered on the PCB.

S7, ion cleaning before bonding: the gas can be used as a cleaning medium to treat the surface of the workpiece through chemical or physical action, so that the pollutant removal at the molecular level is realized, and the surface activity of the workpiece is improved. The removed pollutants can be organic matters, oxides, micro-particle pollutants and the like, so that the surface of the PCB is clean before the next process, and the surface bonding capability of the surface of the PCB and the plastic packaging material is enhanced.

S8, bonding: copper wires or gold wires can be used to connect the chip function pads to external PCB circuit pads for electrical connection.

S9, dispensing: the semiconductor protective glue can be used for being sprayed on the chip and the bonding wires to protect the chip and the bonding wires from being damaged in the moving process.

S10, baking after dispensing: the protective paste may be cured by baking it in an oven.

S11, brushing glue on a steel mesh: the purpose of this procedure is to apply solder paste to the land areas of the PCB board, including the land areas of the front and bottom surfaces, to facilitate the connection of the frame to these lands, and the connection of the planar coil to the lands.

S12, surface mounting and frame placement: the purpose of this process is to paste the signal modulation chip, sampling unit (such as resistance) and planar coil in the pad area corresponding to the PCB board, including the alignment position of the pad area of the front and bottom surfaces, so that after the next reflow soldering, the signal modulation chip, sampling unit and planar coil can be soldered together correspondingly to form a functional circuit.

S13, reflow soldering: the components are heated by a reflow high-temperature furnace, after the solder paste is melted, all corresponding bonding pads are welded together as a welding medium, and the PCB comprises a signal modulation chip, a sampling unit and a planar coil which can be correspondingly welded on the PCB.

S14, ion cleaning before plastic packaging: the gas can be used as a cleaning medium to treat the surface of the workpiece through chemical or physical action, so that the pollutant removal at the molecular level is realized, and the surface activity of the workpiece is improved. The removed pollutants may comprise organic matters, oxides, micro-particle pollutants and the like, so that all surfaces are clean before the next process, and the surface bonding capability of the object surface and the plastic package material is enhanced.

S15, plastic packaging: can adopt resin encapsulation, and aims to wrap all components by resin, so as to insulate the chip from the external environment, protect the chip from damage and further facilitate heat dissipation of the product

S16, electroplating: the purpose of electroplating is to plate the lead pins of the frame with pure tin, and the copper pins can be protected from oxidization after the tin is plated on the product pins.

S17, baking after electroplating: the purpose of post-plating baking is to reduce and delay the generation of tin whiskers, which can cause short circuits of pins of the finished product after chip packaging, and to remove moisture on the surface of the product during plating at high temperature.

S18, printing: the purpose of printing is to print an identity label on the front surface of a product through laser, so that the product model and the production batch information can be conveniently identified in the subsequent process.

S19, cutting ribs and forming: the whole product is cut into single products by die equipment for rib cutting and forming, and the external leading-out pins are bent into shapes and sizes required by fixation. The SMT can be conveniently and smoothly finished after the user receives the product.

The above embodiments do not limit the scope of the present invention. It will be apparent to those skilled in the art that various modifications, combinations, sub-combinations and alternatives are possible, depending on design requirements and other factors. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of the present invention.

Claims

1. A closed loop current sensor, comprising:

a U-shaped magnetic core;

a planar coil surrounding the U-shaped magnetic core;

the Hall chip is used for sensing the change of a magnetic field in the U-shaped magnetic core to form a voltage signal, the signal modulation chip is respectively and electrically connected with the Hall chip and the planar coil, and the signal modulation chip is used for amplifying the voltage signal output by the Hall chip and outputting a current signal; the planar coil is used for compensating the magnetic field in the U-shaped magnetic core according to the current signal.

2. The closed loop current sensor of claim 1, wherein the U-shaped magnetic core comprises a first T-shaped magnetic core body, a second T-shaped magnetic core body, and a bend;

the first T-shaped magnetic core body and the second T-shaped magnetic core body are oppositely arranged, and the first T-shaped magnetic core body and the second T-shaped magnetic core body are connected through the bending part to form the U-shaped magnetic core.

3. The closed loop current sensor of claim 2, further comprising a PCB board;

the U-shaped magnetic core is inserted into the PCB from one side of the PCB.

4. The closed loop current sensor of claim 3 wherein the PCB board includes a recess, the bend being at least partially disposed within the recess.

5. The closed loop current sensor of claim 3, wherein the hall chip and the signal modulation chip are both disposed on one side of the PCB;

the vertical projection of the Hall chip on the PCB is at least partially overlapped with the vertical projection of the first T-shaped magnetic core body and the second T-shaped magnetic core body on the PCB.

6. The closed loop current sensor of claim 5, wherein the planar coil comprises a coil body and first and second pins lead from the coil body, the PCB board comprising first and second pads;

the first bonding pad and the second bonding pad are arranged on the other side of the PCB, when the U-shaped magnetic core is inserted on the PCB, the first pin is attached to the first bonding pad, and the second pin is attached to the second bonding pad.

7. The closed loop current sensor of claim 5, wherein the planar coil comprises a coil body and first and second pins lead from the coil body, the PCB board comprising first and second pads;

the first bonding pad and the second bonding pad are arranged on one side of the PCB, when the U-shaped magnetic core is inserted on the PCB, the first pin is connected with the first bonding pad through a first wire, and the second pin is connected with the second bonding pad through a second wire.

8. The closed loop current sensor of claim 3, further comprising a sampling unit and a plurality of external pins;

the first end of the sampling unit is connected with the signal modulation chip, the second end of the sampling unit is connected with the planar coil, and the sampling unit is used for collecting current signals provided by the signal modulation chip;

and the external pins are welded on the PCB.

9. The closed loop current sensor of claim 1, wherein the hall chip comprises a gallium arsenide hall chip or an indium antimonide hall chip.

10. The closed loop current sensor of claim 1 wherein the material of the U-shaped magnetic core is a nanocrystalline soft magnetic material.