A single magnetic ring dual-range high-precision closed-loop current sensor

Abstract

The present invention discloses a single magnetic ring dual-range high-precision closed-loop current sensor, which includes a nearly semi-circular soft magnetic magnetic ring with two symmetric air gaps, two groups of magnetic sensing probes, an openable and closable soft magnetic magnetic ring fixing component, a low-noise signal processing circuit, and a host computer. Current detection is respectively carried out in the magnetic field signal attenuation area and the air gap within a single circular magnetic ring to achieve single magnetic ring dual-range current detection. The low-noise signal processing circuit of the present invention improves the range, precision, and linearity of the current sensor. The obtained high-precision dual-range current sensor has high sensitivity, a wide working range, good linearity, high bandwidth, and uses a single magnetic ring to complete the design of the dual-range current sensor, and also has the characteristics of low cost and small volume.

Description

Technical Field

[0001] The present invention belongs to the technical field of magnetic sensor applications, and relates to a single magnetic ring dual-range high-precision closed-loop current sensor. Background Art

[0002] A current sensor is a device for detecting current, and is generally applied to the actual measurement and protection systems of current, such as fields of photovoltaic, wind power, electric power, smart grid, railway locomotive, aerospace, new energy vehicles, etc. As a main detection component, the current sensor plays a crucial role in ensuring the safety and stability of the system. For example, in the battery management system of new energy vehicles, the typical measurement range of current is from 10 milliamperes to 1000 amperes. When the vehicle is in a temporary stop and waiting state, the current is about 1 ampere, and when the battery is trickle charging, the current value is from several milliamperes to several tens of milliamperes. If a wide-range current sensor of several hundred amperes is adopted, it is difficult to accurately measure the current. If a small-range current sensor is adopted, the measurement accuracy of small current is high, but it cannot measure the current of several hundred amperes during normal charging and discharging of the vehicle.

[0003] Most of the existing current sensors are single-range detection, but different ranges of current detection are required in many occasions. Therefore, the same current sensor cannot meet the needs. To achieve dual-range measurement, one solution is to adopt multiple current sensors, but it will increase the system complexity, volume and the number of interfaces; another solution is to encapsulate two magnetic ring structures and sensing units together through encapsulation method to achieve different-range measurement, but its structure is still relatively complex, the volume is large, and the accuracy is not high. For example, the patented technologies with the authorized publication numbers of CN109142837A and CN104237623A both adopt two magnetic core structures and Hall elements to detect currents of different ranges. Therefore, the magnetic core cost is high, the volume is large, and the sensitivity of the Hall element itself is not high, and the working range is small, resulting in a small range, low accuracy and poor linearity of the current sensor.

[0004] In summary, the existing dual-range current sensors have problems such as small range, low accuracy, low linearity, large volume, etc., which do not conform to the development trend of product miniaturization and integration. Summary of the Invention

[0005] The purpose of the present invention is to provide a single magnetic ring dual-range high-precision closed-loop current sensor, aiming to solve and make up for the deficiencies existing in the prior art, improve the detection accuracy, working bandwidth and linearity of the dual-range current sensor, enable it to measure both wide-range and small-range currents simultaneously, and reduce the volume and cost, which is more in line with the integration and miniaturization trends of products.

[0006] The present invention includes a soft magnetic magnetic ring with two symmetric air gaps (single magnetic ring structure), a high-precision small-range magnetic sensing probe, a high-stability large-range magnetic sensing probe, an openable and closable soft magnetic magnetic ring fixing component, a low-noise signal processing circuit, and a result display host computer.

[0007] The soft magnetic magnetic ring with two symmetric air gaps includes an upper half magnetic ring and a lower half magnetic ring, which are of the same size and are concentrically and precisely fixed and assembled by two parts, namely an upper half fixing component and a lower half fixing component, with two symmetric air gaps left. The function of the two magnetic rings is to have a magnetic focusing effect on the magnetic field generated by the current signal to be measured, and at the same time, it can isolate the interference of external stray magnetic fields. The main function of the air gap between the magnetic rings is to shunt the magnetic field signal generated by the current to be measured; the soft magnetic magnetic ring enhances the magnetic field signal generated by the small current signal in the two air gaps of the magnetic ring, and can shunt and attenuate the magnetic field signal generated by the large current signal in the area between the inner wall of the magnetic ring and the center of the magnetic ring into a weaker magnetic field signal. Therefore, the magnetic field signal components sensed and detected at different positions in the magnetic ring are different.

[0008] The two sets of magnetic sensing probes are high-sensitivity magnetic sensors. Among them, the high-precision small-range magnetic sensing probe is arranged at the middle position between the two air gaps to detect the enhanced magnetic field signal in the air gap when detecting a small current signal, so as to improve the accuracy of current detection; the high-stability large-range magnetic sensing probe is arranged at the position between the inner wall of the magnetic ring and the wire in the radial direction of the perpendicular bisector of the semi-circular magnetic ring to detect the magnetic field signal generated after shunting and attenuation when detecting a large current signal, so as to increase the current detection range. Specifically, when the high-precision small-range magnetic sensing probe is placed at the middle position of the air gap, the sensed magnetic field signal is the largest relative to other positions of the magnetic ring, and the change of the magnetic field signal caused by the magnetic field signal generated by the primary current is more obvious. Therefore, the detected magnetic field range at this position is small but the accuracy is high, that is, it can detect small-range and high-precision current; when the high-stability large-range magnetic sensing probe is placed at the position between the inner wall of the magnetic ring and the wire in the radial direction of the perpendicular bisector of the semi-circular magnetic ring, the sensed magnetic field signal is small, and its output still changes linearly when detecting a large current. Therefore, the detected magnetic field range at this position is large, that is, it can detect current signals with a wide range. Through the position settings of the two sets of magnetic sensing probes and the soft magnetic shunt structure, the detection accuracy of the current sensor can be improved, and the working range of the current sensor can be increased, realizing a dual-range high-precision current sensor.

[0009] The openable and closable magnetic ring fixing component includes an upper half fixing component and a lower half fixing component. Both the upper half fixing component and the lower half fixing component are provided with magnetic ring fixing grooves for concentrically and precisely fixing and assembling two nearly semi-circular soft magnetic magnetic rings with symmetric air gaps; the magnetic ring fixing component can accurately position and fix the two sets of magnetic sensing probes and the soft magnetic shunt structure; through the screw holes on the upper opening and closing component and the lower opening and closing component, the entire fixing component can be freely opened and closed for the access and disconnection of the wire of the current to be measured; for the circuit to be measured, it can be assembled and measured in situ without damaging the original circuit structure.

[0010] The function of the low-noise signal processing circuit is to amplify the weak differential signal output by the magnetic sensor and convert it into a current signal, and then drive the feedback coil. The feedback coil is dozens of turns of copper enameled wire wound on the lower half of the magnetic ring. The magnetic field signals generated by the feedback coil in the directions of the sensitive axes of the two magnetic sensors are similar in magnitude and opposite in direction to the magnetic field signals of the measured primary current signal in these directions, making the entire system form a closed-loop structure, thereby improving the range, sensitivity, and linearity of the dual-range current sensor. The low-noise signal processing circuit also includes performing analog-to-digital conversion and waveform conversion on the differential voltage signals at both ends of the sampling resistor, and transmitting them to the MCU for data processing to obtain the magnitude and frequency values of the primary current.

[0011] The low-noise signal processing circuit can switch to the output end of the magnetic sensing probe for small current range detection or the output end of the magnetic sensing probe for large current range detection according to the requirements of the two detection ranges of the current sensor, and the low-noise signal processing circuits for the two current detection ranges are shared; the amplifier used in the circuit is an operational amplifier with low noise and high voltage slew rate, and an RC filter circuit is added at the power supply end.

[0012] The described low-noise signal processing circuit includes a signal amplification module, a signal feedback module, and a signal conditioning module. Among them, the signal amplification module includes an instrumentation amplifier and a power amplifier, which are connected to the signal output end of the magnetic sensing probe, amplify and process the differential voltage signal output by the magnetic sensing probe, and drive the subsequent signal feedback coil. Among them, the signal feedback module includes a feedback coil and a series-connected sampling resistor. The feedback coil is wound on the lower half of the magnetic ring, and the magnetic field signals generated at the two magnetic sensing probes cancel out the magnetic field generated by the primary signal current at this position, realizing closed-loop feedback. Among them, the sampling resistor is connected in series with the feedback coil, and the feedback current signal is measured through voltage sampling and analysis. Among them, the signal conditioning module includes a Schmidt amplifier, a differential amplifier, an ADC, and an MCU. The Schmidt amplifier is used to convert the sine wave into a square wave signal for transmission to the MCU for processing when measuring an AC signal, and the frequency value of the signal is obtained through calculation by the MCU; after the differential amplifier and the ADC amplify, filter, and perform analog-to-digital conversion on the signals at both ends of the sampling resistor, they are transmitted to the MCU for processing, and the magnitude of the sampling signal is obtained through calculation by the MCU.

[0013] The described single magnetic ring structure can achieve high-precision small-range current detection and high-stability large-range current detection, and can measure the signals of any one range alone or the signals of both ranges simultaneously.

[0014] The magnetic sensing selected is giant magnetoresistive sensing, anisotropic magnetoresistive sensing, or tunnel junction magnetoresistive sensor.

[0015] The magnetic sensor is composed of a push-pull Wheatstone full-bridge structure consisting of four magnetoresistors. It is placed at different positions inside the magnetic ring. When the magnetic field signal in the direction perpendicular to the chip surface at this position changes, the Wheatstone bridge provides a differential voltage output. The instrumentation amplifier amplifies the differential signal and outputs it to the power amplifier to drive the feedback coil.

[0016] The power amplifier is an operational amplifier that converts a voltage signal to a current signal. Its function is to make the current change with the voltage signal output by the instrumentation amplifier and use this current to drive the feedback coil.

[0017] The feedback coil is a spiral coil structure wound with copper enameled wire on the lower half of the magnetic ring and is made of non-magnetic high-conductivity copper core enameled wire. Under the drive of the feedback current, a magnetic field that is similar in magnitude and opposite in direction to the primary current in the sensitive axis direction of the magnetic sensor is generated, forming a closed-loop feedback system.

[0018] The sampling resistor is a high-power thick-film resistor with a low temperature coefficient and high precision. It is connected in series with the feedback coil. The differential voltage signal across the sampling resistor is detected, amplified by a differential amplifier, and then converted by an ADC through analog-to-digital conversion and transmitted to the MCU for signal processing to obtain the signal amplitude; when the primary signal is an AC signal, the AC sine signal across the sampling resistor is converted into a square wave signal by a Schmitt trigger and transmitted to the MCU for signal processing to obtain the signal bandwidth.

[0019] The result display host computer is a human-computer interaction interface on the PC side that can display the amplitude and frequency values of the current to be tested. After the MCU processes the data transmitted by the Schmitt trigger and the ADC, it is transmitted to the host computer for display through the serial port.

[0020] Furthermore, the magnetic ring is made of soft magnetic materials such as iron-based alloys and amorphous soft magnetic alloys with low coercivity and high magnetic permeability.

[0021] Furthermore, the magnetic ring fixing component includes a magnetic ring fixing outer shell and fixing screws. The magnetic ring fixing outer shell is made of non-magnetic insulating material, preferably resin; the upper and lower magnetic ring positioning parts are fixed by screws so that they can be freely opened and closed for convenient testing.

[0022] Compared with the prior art, the beneficial effects of the present invention are:

[0023] Only one magnetic ring structure is used to realize the measurement of a dual-range current sensor, with a small volume and low cost;

[0024] By adopting a high-sensitivity magnetic sensing probe and a magnetic field signal feedback coil, the performance of the current sensor such as sensitivity, resolution, linearity, and working range is improved;

[0025] It has advantages such as good performance, feasibility, and easy processing. Brief Description of the Drawings

[0026] Figure 1 It is a schematic diagram of the overall system of the present invention;

[0027] Figure 2 It is a schematic diagram of the opening and closing type magnetic ring fixing component of the present invention;

[0028] Figure 3 It is a schematic diagram of the magnetic ring and multi-sensor fusion structure of the present invention. Detailed Description of the Invention

[0029] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of the present invention.

[0030] In the accompanying drawings of this embodiment, the same or similar reference numerals correspond to the same or similar components; in the description of the present invention, it should be understood that if there are terms such as "upper", "lower", "left", "right", "vertical", "horizontal", etc. indicating the orientation or positional relationship, they are based on the orientation or positional relationship shown in the accompanying drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the terms describing the positional relationship in the accompanying drawings are only for illustrative purposes and cannot be understood as a limitation of this patent. For those of ordinary skill in the art, the specific meanings of the above terms can be understood according to specific circumstances.

[0031] The implementation of the present invention will be described in detail below in conjunction with specific embodiments.

[0032] As Figure 1 shown, the present invention provides a single magnetic ring dual-range high-precision closed-loop current sensor, including a wire under test 1-1, an upper half magnetic ring 1-2, a lower half magnetic ring 1-3, a left air gap 1-4, a right air gap 1-5, a first magnetic sensor 1-6, a second magnetic sensor 1-7, a feedback coil 1-8, a first instrumentation amplifier 1-9 and a second instrumentation amplifier 1-10, a single-pole double-throw switch 1-11, a power amplifier 1-12, a sampling resistor 1-13, a Schmitt trigger 1-14, a differential amplifier 1-15, an ADC 1-16, an MCU 1-17, and a host computer 1-18.

[0033] The wire under test 1-1 is a copper rod, which vertically passes through the plane where the magnetic ring is located inward, and the copper rod coincides with the center of the magnetic ring.

[0034] The upper magnetic ring 1-2 and the lower magnetic ring 1-3 are made of soft magnetic materials and are in an overall circular ring shape. In this embodiment, the selected material is iron-based nanocrystalline material, with an inner diameter of 40 mm, an outer diameter of 60 mm, and symmetric air gaps on both the left and right sides.

[0035] Both the left air gap 1-4 and the right air gap 1-5 are symmetric air gaps with a width of 1.6 mm between the upper and lower magnetic rings, and the shunting and magnetic focusing effects in the air gaps are obvious.

[0036] In this embodiment, the first magnetic sensor 1-6 and the second magnetic sensor 1-7 are tunnel magnetoresistance (TMR) sensors. Among them, the first magnetic sensor 1-6 is used for measuring small-range and high-precision current, and is located at the middle position of the right air gap 1-5, with its sensitive axis direction vertically downward; the second magnetic sensor 1-7 is used for measuring wide-range current, and is located at the position between the inner wall of the magnetic ring and the wire in the radial direction of the perpendicular bisector of the semi-circular magnetic ring, with its sensitive axis direction horizontally to the left.

[0037] The feedback coil 1-8 is made of enameled copper wire with a diameter of 0.35 mm, and is wound symmetrically from right to left on the lower magnetic ring with respect to the midline of the lower magnetic ring, and is located at the post-stage of the sampling resistor. Inside the magnetic ring, the magnetic field signal generated by the feedback current in the coil cancels the magnetic field signal generated by the primary current to achieve the effect of magnetic balance.

[0038] Both the first instrumentation amplifier 1-9 and the second instrumentation amplifier 1-10 are differential input operational amplifiers with low noise, high precision, and high common-mode rejection ratio, and appropriate amplification factors are set in two ranges.

[0039] The single-pole double-throw switch 1-11 is a sliding switch. The common terminal is the input of the power amplifier, and the other end is the output terminals of the first instrumentation amplifier 1-9 and the second instrumentation amplifier 1-10, which is used to switch the range.

[0040] The power amplifier 1-12 is a high-voltage and high-current operational amplifier that converts voltage signals into current signals, is located at the post-stage of the single-pole double-throw switch, and is connected in a follower mode, and is used to drive the feedback coil 1-8 to generate current.

[0041] The sampling resistor 1-13 is a high-power thick film resistor with a resistance value of 1 ohm, is located at the post-stage of the power amplifier 1-12 and the pre-stage of the feedback coil 1-8. The voltage across the sampling resistor is sampled, and analog-to-digital conversion and waveform conversion are respectively performed, and then input to the MCU 1-17 for data processing and output to the upper computer 1-18 at the post-stage for display.

[0042] The Schmitt trigger 1-14 is a four-channel two-input NAND gate, which converts the analog signal sine wave into a square wave signal when measuring the frequency of the AC signal, so as to transmit it to the MCU for data processing and calculating the signal frequency.

[0043] The differential amplifier 1-15 uses a low-noise, low-distortion, high-speed fully differential amplifier to convert the single-ended voltage signal at the front end into a differential voltage signal for transmission to the ADC for acquisition.

[0044] The ADC 1-16 is a 32-bit low-noise, low-power single-channel analog-to-digital converter that converts the analog signal into a digital signal for easy transmission to the MCU for data processing.

[0045] The MCU 1-17 uses an stm32f1 series single-chip microcomputer, which has the characteristics of low power consumption, high integration, rich serial ports and peripherals, and its function is to perform serial port transmission and data processing.

[0046] The host computer 1-18 is a display page on the PC side, which displays the data transmitted by the MCU 1-16 through the serial port, so as to view the measured current value and frequency value on the PC side page.

[0047] As Figure 2 shown, the figure shows Figure 1 During the implementation process, the magnetic ring fixing components of the wire under test 1-1, the upper half magnetic ring 1-2, the lower half magnetic ring 1-3, the first magnetic sensor 1-6 and the second magnetic sensor 1-7. It includes a wire slot under test 2-1, an upper half magnetic ring slot 2-2, a lower half magnetic ring slot 2-3, an upper half fixing component 2-4, a lower half fixing component 2-5, an upper half fixing part left ear 2-6, a lower half fixing part left ear 2-7, a front screw opening 2-8, a rear screw opening 2-9, an upper opening and closing part 2-10, a lower opening and closing part 2-11, an upper screw opening 2-12, a lower screw opening 2-13, a coil slot 2-14 and a component base 2-15.

[0048] The wire slot under test 2-1 is formed by leaving a semi-circle with a radius of 9 mm on each of the upper and lower components. After the components are closed, the wire under test is fixed in the wire slot to fix the wire under test.

[0049] The upper half magnetic ring slot 2-2 and the lower half magnetic ring slot 2-3 are recessed structures, and the two nearly semi-circular magnetic rings are accurately clamped into the slots to fix the magnetic rings.

[0050] The upper half fixing component 2-4 includes half of the wire slot under test 2-1, the upper half magnetic ring slot 2-2, the upper screw opening 2-12, and the rear screw opening 2-9, which is used to fix the upper half magnetic ring 1-2 and form an openable and closable shell with the lower half fixing component 2-5.

[0051] The lower half fixing component 2-5 includes half of the wire slot under test 2-1, the lower half magnetic ring slot 2-3, the lower screw opening 2-13, the front screw opening 2-8, the coil slot 2-14, and the component base 2-15, which is used to fix the first magnetic sensor 1-6, the second magnetic sensor 1-7 and the lower half magnetic ring 1-3, and form an openable and closable shell with the upper half fixing component 2-4.

[0052] The left ear 2-6 of the upper fixing part and the left ear 2-7 of the lower fixing part are respectively on the left side of the upper fixing component 2-4 and the lower fixing component 2-5, both are circles with a diameter of 10 mm, and are connected by screw through holes to fix the upper fixing component 2-4 and the lower fixing component 2-5;

[0053] The front screw hole 2-8 and the rear screw hole 2-9 are respectively round holes with diameters of 5.4 mm and 4.2 mm, and are respectively at the central positions of the left ear 2-6 of the upper fixing part and the left ear 2-7 of the lower fixing part. The function is to form an M5 screw through hole to fix the relative positions of the upper fixing component 2-4 and the lower fixing component 2-5.

[0054] The upper opening and closing part 2-10 and the lower opening and closing part 2-11 are respectively on the right side of the upper fixing component 2-4 and the lower fixing component 2-5, with a thickness of 4 mm and a length of 10 mm each, and are connected by screw through holes to enable the upper fixing component 2-4 and the lower fixing component 2-5 to open and close freely.

[0055] The upper screw hole 2-12 and the lower screw hole 2-13 are respectively round holes with diameters of 5.4 mm and 4.2 mm, and are respectively at the central positions of the upper opening and closing part 2-10 and the lower opening and closing part 2-11. The two form an M5 screw through hole to open or close the upper fixing component 2-4 and the lower fixing component 2-5 from the right side.

[0056] The coil groove 2-14 is a groove on the lower fixing component 2-5, 1 mm above and below the lower magnetic ring groove 2-3, to fix and place the feedback coil 1-8.

[0057] The component base 2-15 is used to support the entire fixing component so that it can be placed stably on the operating plane.

[0058] As Figure 3 shown, the figure shows Figure 1 a simplified magnetic ring and multi-sensor fusion structure of the principle in the implementation process, Figure 3 (a) includes two nearly semi-circular magnetic rings 3-1, 3-2 and two magnetic sensors 3-3, 3-4 placed at different positions inside the magnetic rings. Figure 3 (b) includes two nearly semi-circular magnetic rings 3-5, 3-6 and four magnetic sensors 3-7, 3-8, and the four magnetic sensors are divided into two groups and placed at mutually perpendicular and symmetric positions inside the magnetic rings.

[0059] The nearly semi-circular magnetic rings 3-1, 3-2, 3-5, and 3-6 are made of iron-based nanocrystalline materials. This soft magnetic material has the advantages of low coercivity, high magnetic permeability, and good temperature stability. The magnetic rings gather the magnetic field signals generated by the primary current within the magnetic rings and have the function of preventing external magnetic field interference. There is no soft magnetic material in the air gap left between the two nearly semi-circular magnetic rings. The magnetic field signals gather in the air gap, and the magnetic field signals become larger.

[0060] The magnetic sensors 3-3 and 3-4 are both tunnel magnetoresistance (TMR) sensors. The magnetic sensor 3-3 is a small-range current sensor, and the magnetic sensor 3-4 is a wide-range current sensor.

[0061] The magnetic sensors 3-7 and 3-8 are two groups of magnetic sensing chips. In this embodiment, two tunnel magnetoresistance (TMR) sensors of the same model are used. Among them, the magnetic sensor 3-7 is placed in the middle of two symmetrical air gaps to collect the larger magnetic shunt signals in the middle of the air gap to achieve the design of a small-range current sensor; among them, the magnetic sensor 3-8 is placed at the position between the inner wall of the magnetic ring and the wire in the radial direction of the mid-perpendicular in the two nearly semi-circular magnetic rings. The magnetic field signal in the attenuation layer is weak, and the design of a wide-range current sensor can be achieved. The signals collected by the two groups of magnetic sensors are output to the MCU for data fusion after passing through the low-noise signal processing circuit. The weighted average fusion and filtering algorithms are used to process the data of the two magnetic sensing chips in the same group.

[0062] The specific implementation process of the present invention is as follows: Place the upper half of the magnetic ring into the slot of the upper half magnetic ring fixing part, wind the feedback coil around the lower half magnetic ring and place the lower half magnetic ring into the slot of the lower half magnetic ring fixing part. Then fix and attach two magnetic sensor chips at the corresponding positions, and fix and attach its PCB probe board at the rear side of the magnetic ring fixing part. Fix and tighten the upper and lower magnetic ring fixing parts with M5 screws. Pass a current through the wire to be measured, with its direction perpendicular to the plane and inward, generating a clockwise magnetic field in space. Most of the magnetic field is concentrated inside the magnetic ring by the magnetic ring, and a smaller leakage magnetic field is generated at the air gap. The magnetic field signals at the two positions where the magnetic sensors are placed are parallel to the sensitive axis of the magnetic sensors. The magnetic sensors detect the magnetic field change and provide a differential voltage output to the instrumentation amplifier. The instrumentation amplifier amplifies and processes the weak differential voltage signal, and the power amplifier linearly converts the voltage signal into a current signal to drive the feedback coil. The feedback coil generates a counterclockwise magnetic field. Finally, the current value on the feedback coil stabilizes at a smaller value, and then the voltage value across the sampling resistor is sampled and read. After data processing and appropriate calibration, the magnitude of the original current to be measured can be judged by the value of this voltage signal. At the same time, the voltage signal on the sampling resistor is differentially amplified and converted into a digital signal by an ADC, and also passes through a Schmitt trigger for waveform conversion to convert the AC sine signal into a square wave signal. The output signals of the ADC and the Schmitt trigger are processed by the MCU and output to the host computer at the PC end through its serial port for display, so as to achieve the purpose of real-time monitoring and display of the magnitude and frequency of the current to be measured on the host computer.

[0063] High-precision small-range current detection and high-stability large-range current detection are realized in a single magnetic ring structure; the signals of the two ranges can be measured separately or simultaneously.

[0064] The present invention combines magnetic sensor technology, magnetic shunt technology, multi-sensor fusion technology and signal feedback technology. It uses magnetic sensor technology to convert the magnetic field signal into a weak electrical signal, and uses magnetic shunt technology to attenuate and shunt the larger magnetic field signal into a smaller magnetic field signal, and selects appropriate positions to place magnetic sensors, so as to achieve the simultaneous measurement of wide-range current and small-range high-precision current. It uses multi-sensor fusion technology to place two groups of magnetic sensors at symmetric positions inside the magnetic ring, and processes the signals output by the two sensors in the same group, greatly reducing the interference caused by environmental changes, avoiding the inaccurate results caused by the process errors of a single sensor itself, and effectively reducing the errors caused by sensor zero drift. It effectively improves the range and accuracy of the current sensor. It adopts a closed-loop structure and feedback technology to cancel the magnetic field signal generated by the primary current to achieve a magnetic balance state, further improving the system working range and sensitivity. And only two identical nearly semi-circular magnetic ring structures are used to complete the current measurement of two ranges and precisions, saving cost and volume.

[0065] It is obvious to those skilled in the art that the present invention is not limited to the details of the above-described exemplary embodiments, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention. Therefore, in all respects, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description, and is intended to cover all changes falling within the meaning and scope of the equivalent elements of the claims. Any reference signs in the claims should not be construed as limiting the claims involved.

Claims

1. A single magnetic ring dual-range high-precision closed-loop current sensor, characterized in that: It includes a soft magnetic magnetic ring with two symmetric air gaps, a high-precision small-range magnetic sensing probe, a high-stability large-range magnetic sensing probe, an openable and closable soft magnetic magnetic ring fixing component, a low-noise signal processing circuit, and a result display host computer; The soft magnetic magnetic ring with two symmetric air gaps is a single soft magnetic circular structure formed by combining two identical nearly semi-circular soft magnetic magnetic rings with two symmetric air gaps; the soft magnetic magnetic ring has a magnetic focusing effect on the magnetic field signals generated by the external field within the two air gaps of the magnetic ring, and has a magnetic shunting effect on the magnetic field signals generated by the external field in the region between the inner wall of the magnetic ring and the center of the magnetic ring; the soft magnetic magnetic ring enhances the magnetic field signals generated by small current signals within the two air gaps of the magnetic ring, and shunts and attenuates the magnetic field signals generated by large current signals in the region between the inner wall of the magnetic ring and the center of the magnetic ring into weaker magnetic field signals; The high-precision small-range magnetic sensing probe and the high-stability large-range magnetic sensing probe are composed of a high-sensitivity magnetic sensing chip and its power supply circuit. Among them, the high-precision small-range magnetic sensing probe is arranged at the middle position between the two air gaps of the magnetic ring to detect the enhanced magnetic field signals generated by small current signals within the air gap of the magnetic ring, improving the accuracy of current detection; another group of high-stability large-range magnetic sensing probes is arranged at a suitable position between the inner wall of the magnetic ring and the wire in the radial direction of the perpendicular bisector of the semi-circular magnetic ring to detect the magnetic field signals generated by large current signals here that are shunted and attenuated by the soft magnetic magnetic ring, improving the working range of the current detection workload; by designing and optimizing the relative position relationship between the two groups of magnetic sensing probes and the soft magnetic shunting structure, both the detection accuracy of the current sensor and the working range of the current sensor can be improved, realizing a single magnetic ring dual-range high-precision current sensor; The openable and closable soft magnetic magnetic ring fixing component includes an upper half fixing component and a lower half fixing component; both the upper half fixing component and the lower half fixing component are provided with magnetic ring fixing grooves for concentrically and precisely fixing and assembling two nearly semi-circular soft magnetic magnetic rings with symmetric air gaps; the magnetic ring fixing component can accurately position and fix the two groups of magnetic sensing probes and the soft magnetic shunting structure; through the screw holes on the upper opening and closing component and the lower opening and closing component, the entire fixing component can be freely opened and closed for the access and disconnection of the measured current wire, so that there is no need to power off the measured circuit, realizing in-situ measurement; The low-noise signal processing circuit can switch to the output end of the magnetic sensing probe for small current range detection or the output end of the magnetic sensing probe for large current range detection according to the signal processing characteristics of the high-precision small-range magnetic sensing probe and the high-stability large-range magnetic sensing probe of the current sensor and the requirements of the measured circuit, and the low-noise signal processing circuits for the two current detection ranges are shared; the amplifier used in the circuit is a low-noise and high-voltage slew rate operational amplifier, and an RC filter circuit is added to the power supply end; The low-noise signal processing circuit includes a signal amplification module, a signal feedback module, and a signal conditioning module; The signal amplification module includes an instrumentation amplifier and a power amplifier, which are connected to the signal output end of the magnetic sensing probe, amplify and process the differential voltage signal output by the magnetic sensing probe, and are used to drive the subsequent signal feedback coil; The signal feedback module described above includes a signal feedback coil and a sampling resistor connected in series therewith. The signal feedback coil is wound around the lower half of the magnetic ring, generating a feedback magnetic field signal at each of the two magnetic sensing probes. This feedback magnetic field signal cancels out the magnetic field signal generated by the primary side signal current at this position, achieving closed-loop feedback. Among them, the sampling resistor is connected in series with the signal feedback coil, and the magnitude of the feedback current signal is measured through voltage sampling and analysis; The signal conditioning module described above includes a Schmitt amplifier, a differential amplifier, an ADC, and an MCU. The Schmitt amplifier is used to convert the sine wave into a square wave signal for transmission to the MCU for processing when measuring an AC signal, and the frequency value of the signal is obtained through calculation by the MCU; after the differential amplifier and the ADC amplify, filter, and perform analog-to-digital conversion on the signals at both ends of the sampling resistor, they are transmitted to the MCU for processing, and the amplitude of the sampling signal is obtained through calculation by the MCU; The result display host computer is a human-computer interaction interface on the PC side that can display information such as the amplitude and frequency value of the current to be tested. After the MCU processes the data transmitted by the Schmitt trigger and the ADC, it is transmitted to the host computer through the serial port to display the relevant information of the measured current.

2. The single magnetic ring dual-range high-precision closed-loop current sensor according to claim 1, characterized in that: The soft magnetic ring described above can achieve high-precision small-range current detection and high-stability large-range current detection, and can measure the signals of any range separately or measure the signals of both ranges simultaneously.

3. The single magnetic ring dual-range high-precision closed-loop current sensor according to claim 1, characterized in that: The magnetic sensing chip described above is selected from a giant magnetoresistive sensing chip, an anisotropic magnetoresistive sensing chip, or a tunneling magnetoresistive sensing chip.

4. The single magnetic ring dual-range high-precision closed-loop current sensor according to claim 1, characterized in that: The power amplifier is an operational amplifier that converts a voltage signal into a current signal.

5. The single magnetic ring dual-range high-precision closed-loop current sensor according to claim 1, characterized in that: The sampling resistor described above is selected as a high-power thick film resistor with a low temperature coefficient and high precision.

6. The single magnetic ring dual-range high-precision closed-loop current sensor according to claim 1, characterized in that: The Schmitt trigger described above is a bistable multivibrator that converts a sine wave into a square wave output.

7. The single magnetic ring dual-range high-precision closed-loop current sensor according to claim 1, characterized in that: The ADC described above is a high-digit single-channel analog-to-digital converter that converts an analog signal into a digital signal.

8. The single magnetic ring dual-range high-precision closed-loop current sensor according to claim 1, characterized in that: The two nearly semi-circular magnetic rings with symmetrical air gaps are made of a soft magnetic material with low coercivity and high magnetic permeability.

9. The single magnetic ring dual-range high-precision closed-loop current sensor according to claim 1, characterized in that: The magnetic ring fixing component described above includes a magnetic ring fixing outer shell and fixing screws, and the magnetic ring fixing outer shell is made of a non-magnetic insulating material.

10. The single magnetic ring dual-range high-precision closed-loop current sensor according to claim 1, characterized in that: The feedback coil described above is wound with a non-magnetic high-conductivity copper core enameled wire.

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