High-precision current sensor, circuit structure and chip

Abstract

The utility model relates to the technical field of current measurement of a power system, in particular to a high-precision current sensor, a circuit structure and a chip, in the high-precision current sensor, a precision resistance Wheatstone bridge is added on the basis of an original TMR Wheatstone bridge, four precision resistors with the same resistance value are adopted, and the precision resistance of the precision resistance Wheatstone bridge is improved. The four precision resistors are respectively connected in parallel with two ends of four TMR units in the original TMR Wheatstone bridge, and the resistance value of the precision resistors is smaller than that of the TMR units. According to the invention, zero offset caused by mismatching of resistance values of the TMR units is weakened, temperature offset caused by temperature is also attenuated, and the resistance value of the precision resistor is not influenced by a magnetic field, so that the influence caused by hysteresis of the TMR element is also greatly reduced, and the reliability of the TMR element is improved. Therefore, the high-precision current sensor which effectively reduces zero offset, temperature drift and hysteresis is realized.

Description

Technical Field

[0001] The present disclosure relates to the technical field of current measurement in power systems, and particularly to a high-precision current sensor, a circuit structure, and a chip. Background Art

[0002] When facing the requirements of the digital transformation of the power grid and the wide-area and distributed panoramic information perception of "power sources, grids, loads, and energy storage" in the power system, in order to strengthen the observable, measurable, and controllable capabilities of the power system, it is necessary to provide high-precision sensing and measurement capabilities for AC and DC magnetic fields and current signals under complex working conditions, so as to provide an important guarantee for the safe operation and reliable power supply of grid equipment.

[0003] Tunnel Magneto Resistance (TMR), as the latest generation of magnetic field measurement technology based on the magnetoresistance effect, has higher sensitivity compared with traditional Hall devices, anisotropic magnetoresistance devices, and giant magnetoresistance devices, and has a wide application prospect in the field of current measurement in power systems. Specifically, in a current sensor, a TMR device is used as a magnetic sensitive element to implement a TMR current sensor. The TMR current sensor adopts an open-loop technology or a closed-loop technology to measure the primary-side current (i.e., the current to be measured).

[0004] However, due to the problems of zero offset, temperature drift, and hysteresis in TMR devices, the TMR current sensor cannot meet the requirements of high-precision and small-current measurement, as Figure 1 shown. To solve the above problems, generally, conditioning chips (such as a temperature compensation module and a bias zero-adjustment module) are used to compensate the temperature drift and zero offset of the TMR device, so as to improve the current measurement accuracy. However, this conventional compensation method requires pre-testing the performance of the TMR device and using corresponding algorithms for compensation. The disadvantage of this method is that it is necessary to test the performance of each TMR device produced, which is not suitable for mass production. In addition, hysteresis generally cannot be compensated, which is also the reason why it is difficult to detect tiny currents using TMR devices. Summary of the Utility Model

[0005] To solve the problems in the related technologies, embodiments of the present disclosure provide a high-precision current sensor, a circuit structure, and a chip.

[0006] In a first aspect, an embodiment of the present disclosure provides a high-precision current sensor, including: a magnetic sensitive unit, where the magnetic sensitive unit includes: an input end, an output end, a TMR Wheatstone bridge, and a precision resistor Wheatstone bridge;

[0007] The TMR Wheatstone bridge includes: a first TMR unit, a second TMR unit, a third TMR unit, and a fourth TMR unit. The first TMR unit, the second TMR unit, the third TMR unit, and the fourth TMR unit are connected to form the arms of the TMR Wheatstone bridge.

[0008] The precision resistor Wheatstone bridge includes: a first precision resistor, a second precision resistor, a third precision resistor, and a fourth precision resistor with the same resistance value. The first precision resistor, the second precision resistor, the third precision resistor, and the fourth precision resistor are connected to form the arms of the precision resistor Wheatstone bridge.

[0009] Wherein, the TMR Wheatstone bridge and the precision resistor Wheatstone bridge are connected such that the first precision resistor is connected in parallel across the two ends of the first TMR unit, the second precision resistor is connected in parallel across the two ends of the second TMR unit, the third precision resistor is connected in parallel across the two ends of the third TMR unit, and the fourth precision resistor is connected in parallel across the two ends of the fourth TMR unit. The TMR Wheatstone bridge and the precision resistor Wheatstone bridge have the same bridge input terminal and bridge output terminal.

[0010] The bridge input terminal is connected to the input terminal and then connected to the power supply, and the bridge output terminal is connected to the output terminal; the resistance value of the precision resistor is less than the resistance value of the TMR unit.

[0011] According to an embodiment of the present disclosure, it further includes: a magnetic core, a coil, a signal processing circuit, and a load resistor.

[0012] The coil is wound around the magnetic core, the magnetic sensing unit is disposed in the open air gap of the magnetic core, the output terminal of the magnetic sensing unit is connected to the input terminal of the signal processing circuit, the output terminal of the signal processing circuit is connected to the first connection terminal of the coil, the second connection terminal of the coil is connected to one end of the load resistor, and the other end of the load resistor is connected to the reference potential.

[0013] According to an embodiment of the present disclosure, the signal processing circuit includes an operational amplifier and a power amplifier; the output terminal of the magnetic sensing unit is connected to the input terminal of the operational amplifier, the output terminal of the operational amplifier is connected to the input terminal of the power amplifier, and the output terminal of the power amplifier is connected to the first connection terminal of the coil.

[0014] According to an embodiment of the present disclosure, the ratio of the resistance value of the precision resistor to the resistance value of the TMR unit is within a set ratio range.

[0015] According to an embodiment of the present disclosure, in the TMR Wheatstone bridge, the sensitive directions of the TMR units on adjacent arms are opposite.

[0016] According to an embodiment of the present disclosure, the precision resistor includes any one of the following: well resistor, diffusion resistor, polysilicon resistor, thin film resistor, and metal film resistor.

[0017] In a second aspect, an embodiment of the present disclosure provides a circuit structure, including: a TMR Wheatstone bridge structure and a precision resistor Wheatstone bridge structure;

[0018] The TMR Wheatstone bridge structure includes 4 TMR units;

[0019] The precision resistor Wheatstone bridge structure includes 4 precision resistors with the same resistance value;

[0020] Wherein, the TMR Wheatstone bridge structure is connected to the precision resistor Wheatstone bridge structure such that the 4 precision resistors are respectively connected in parallel at both ends of the 4 TMR units, and the TMR Wheatstone bridge structure and the precision resistor Wheatstone bridge structure have the same bridge input terminal and bridge output terminal; the resistance value of the precision resistor is less than the resistance value of the TMR unit.

[0021] In a third aspect, an embodiment of the present disclosure provides a chip, including: the high-precision current sensor according to any item in the first aspect, or the circuit structure according to the second aspect.

[0022] According to the technical solution provided by the embodiment of the present disclosure, by adding a precision resistor Wheatstone bridge on the basis of the original TMR Wheatstone bridge, using 4 precision resistors with the same resistance value, and the resistance value of the precision resistor is less than the resistance value of the TMR unit in the TMR Wheatstone bridge, the zero offset caused by the mismatch of the resistance values of the TMR units is weakened, and at the same time, the temperature offset caused by temperature is attenuated. And since the resistance value of the precision resistor is not affected by the magnetic field, the influence caused by the magnetic hysteresis of the TMR element is also greatly reduced. Thus, the influences of zero offset, temperature drift, and magnetic hysteresis on the high-precision current sensor are effectively reduced, and it is not necessary to test the performance of each TMR Wheatstone bridge. Only by knowing the approximate range of the resistance values of the bridge arms of the TMR Wheatstone bridge can batch compensation be carried out.

[0023] It should be understood that the above general description and the following detailed description are only exemplary and explanatory, and cannot limit the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Combined with the drawings, through the following detailed description of non-limiting embodiments, other features, objects, and advantages of the present disclosure will become more obvious. In the drawings:

[0025] Figure 1 A circuit structure schematic diagram of a TMR Wheatstone bridge in the prior art is shown;

[0026] Figure 2 A circuit connection diagram of a high-precision current sensor according to an embodiment of the present disclosure is shown;

[0027] Figure 3 A schematic diagram showing circuit connections of a magnetic sensitive unit in a high-precision current sensor according to an embodiment of the present disclosure is shown;

[0028] Figure 4 A circuit connection diagram of a magnetic sensitive unit in another high-precision current sensor according to an embodiment of the present disclosure is shown. DETAILED DESCRIPTION

[0029] Hereinafter, exemplary embodiments of the present disclosure will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily implement them. In addition, for the sake of clarity, parts not related to the description of the exemplary embodiments are omitted in the accompanying drawings.

[0030] In the present disclosure, it should be understood that terms such as "include" or "have" are intended to indicate the presence of features, numbers, steps, actions, components, parts, or combinations thereof disclosed in the present specification, and are not intended to exclude the possibility that one or more other features, numbers, steps, actions, components, parts, or combinations thereof exist or are added.

[0031] It should also be noted that, in the absence of conflict, the embodiments and features of the embodiments of the present disclosure may be combined with each other. The present disclosure will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0032] In this disclosure, if it involves operations of obtaining user information or user data or displaying user information or user data to others, such operations are all authorized and confirmed by the user, or actively selected by the user.

[0033] As the energy industry transforms towards clean, low-carbon, safe and efficient, power grids and new energy vehicles have an urgent need for high-sensitivity and high-reliability sensors. In the demand for high-sensitivity and high-reliability current sensors, TMR devices have higher sensitivity than traditional Hall devices, anisotropic magnetoresistive devices and giant magnetoresistive devices. Therefore, TMR devices can be used as magnetic sensitive units to realize highly sensitive TMR current sensors, and open-loop or closed-loop technology can be used to measure the magnitude of the current to be measured. Among them,

[0034] When using open-loop technology, the magnitude of the magnetic field generated by the primary current (i.e., the current to be measured) is measured, and the magnitude of the primary current is inferred from the magnitude of the magnetic field. When using closed-loop technology, a closed-loop feedback loop is formed to keep the magnetic field felt by the magnetic sensitive element at zero, thereby making the primary current and the secondary current measured in a certain ratio, thus achieving the measurement of the primary current.

[0035] The inventors found that current measurement generally adopts closed-loop technology at present. Compared with open-loop technology, closed-loop technology can enhance the resistance of TMR current sensors to adverse factors such as external noise, and allows precise control and adjustment of output signals. In an ideal magnetic field-free environment, the output voltage of a TMR current sensor using closed-loop technology is zero. However, in practice, due to factors such as the internal material properties and manufacturing processes of TMR devices, the TMR devices have non-zero outputs, are susceptible to temperature, and have hysteresis problems, all of which directly affect the measurement accuracy of TMR current sensors, especially in applications that require high-precision magnetic field measurement.

[0036] When using a conditioning chip to compensate for the temperature drift and zero offset of TMR devices, it is necessary to test the performance of TMR devices in advance, use corresponding algorithms for compensation, and more importantly, perform performance tests on each TMR device leaving the factory. At the same time, hysteresis generally cannot be compensated, which also makes it difficult for TMR current sensors to detect tiny currents.

[0037] The present disclosure provides a high-precision current sensor, including: a magnetic-sensitive unit, and the magnetic-sensitive unit includes: an input end, an output end, a TMR Wheatstone bridge, and a precision-resistor Wheatstone bridge; the TMR Wheatstone bridge includes: a first TMR unit, a second TMR unit, a third TMR unit, and a fourth TMR unit, and the first TMR unit, the second TMR unit, the third TMR unit, and the fourth TMR unit are connected to form the bridge arms of the TMR Wheatstone bridge; the precision-resistor Wheatstone bridge includes: a first precision resistor, a second precision resistor, a third precision resistor, and a fourth precision resistor with the same resistance value, and the first precision resistor, the second precision resistor, the third precision resistor, and the fourth precision resistor are connected to form the bridge arms of the precision-resistor Wheatstone bridge; wherein, the TMR Wheatstone bridge and the precision-resistor Wheatstone bridge are connected such that the first precision resistor is connected in parallel across the two ends of the first TMR unit, the second precision resistor is connected in parallel across the two ends of the second TMR unit, the third precision resistor is connected in parallel across the two ends of the third TMR unit, the fourth precision resistor is connected in parallel across the two ends of the fourth TMR unit, and the TMR Wheatstone bridge and the precision-resistor Wheatstone bridge have the same bridge input end and bridge output end; the bridge input end is connected to the input end and then connected to a power supply, and the bridge output end is connected to the output end; the resistance value of the precision resistor is less than the resistance value of the TMR unit.

[0038] Based on the original TMR Wheatstone bridge, the present disclosure adds a precision resistor Wheatstone bridge composed of four precision resistors with the same resistance value, and the resistance value of the precision resistor is less than the resistance value of the TMR unit in the TMR Wheatstone bridge, which weakens the zero offset caused by the mismatch of the resistance values of the TMR units. Moreover, since the resistance value of the precision resistor is not affected by the magnetic field and is very little affected by the temperature, the temperature offset of the high-precision current sensor is greatly attenuated, and the influence brought by hysteresis is also weakened.

[0039] Figure 2 Fig. shows a schematic circuit connection diagram of a high-precision current sensor according to an embodiment of the present disclosure.

[0040] As Figure 2 shown, the high-precision current sensor includes: a magnetic sensitive unit, a magnetic core, a coil, a signal processing circuit, and a load resistor. The coil is wound around the magnetic core, the magnetic sensitive unit is disposed in the open air gap of the magnetic core, the output end of the magnetic sensitive unit is connected to the input end of the signal processing circuit, the output end of the signal processing circuit is connected to the first connection terminal of the coil, the second connection terminal of the coil is connected to one end of the load resistor, and the other end of the load resistor is connected to a reference potential.

[0041] According to an embodiment of the present disclosure, the signal processing circuit includes an operational amplifier and a power amplifier; the output end of the magnetic sensitive unit is connected to the input end of the operational amplifier, the output end of the operational amplifier is connected to the input end of the power amplifier, and the output end of the power amplifier is connected to the first connection terminal of the coil.

[0042] During operation, when the current to be measured passes through the conductor in the magnetic core, a magnetic field will be generated around the conductor (the direction and intensity of the magnetic field are related to the magnitude and direction of the current), and then the generated magnetic field will be concentrated in the open air gap by the magnetic core. After the magnetic sensitive unit senses the magnetic field, it outputs a voltage signal to the signal processing circuit for amplification and other processing and then outputs it to the coil, so that the magnetic field generated by the current generated by the output signal on the coil is opposite to the magnetic field concentrated by the magnetic core in its open air gap. When the magnetic field sensed by the magnetic sensitive unit tends to be stable, that is, in a magnetic equilibrium state, at this time, the current on the load resistor forms a linear proportional relationship with the current to be measured. Therefore, the current to be measured can be obtained by measuring the current on the load resistor.

[0043] Specifically, one end of the load resistor is connected to the reference potential (i.e., the 0V potential point), and the current flowing through the load resistor can be measured by connecting a voltmeter in parallel across the two ends of the load resistor or by connecting an ammeter in series in the line where the load circuit is located. Those skilled in the art can understand that the measurement method of the current on the load resistor is not a technical means for limiting the protection scope of the present disclosure. For example, a multimeter, a digital oscilloscope, etc. can also be used.

[0044] After research, the inventors found that by connecting a precision resistor Wheatstone bridge composed of 4 precision resistors with the same resistance value on the basis of the TMR Wheatstone bridge, the zero offset, temperature offset, and hysteresis problems caused by factors such as the internal material characteristics and manufacturing process of the TMR unit can be solved. The specific reasons are as follows:

[0045] When there is a zero offset in the TMR unit, that is, there is a certain resistance value even without an external magnetic field, and this resistance value will cause a certain current to flow through. However, when it is connected in parallel with the precision resistor, due to the characteristics of the parallel circuit, part of the current will flow through the precision resistor, thereby reducing the current flowing through the TMR unit, which is equivalent to compensating for the zero offset of the TMR unit.

[0046] When the TMR unit is connected in parallel with a precision resistor with a stable resistance value that is not affected by temperature, the equivalent resistance of the entire parallel circuit will be affected by both the TMR unit and the precision resistor. When the temperature changes, the resistance value of the TMR unit will change, but due to the presence of the precision resistor, the change amount of the resistance of the entire parallel circuit will be smaller than that when the TMR unit changes alone. By connecting the precision resistor in parallel, the zero offset change of the TMR unit caused by temperature can be attenuated.

[0047] Although connecting the precision resistor in parallel does not directly affect the hysteresis characteristics of the TMR unit, it indirectly affects the measurement result by changing the overall response of the circuit. Specifically, since the total resistance of the parallel circuit is a function of the branch resistors, when the TMR unit exhibits a non-linear response due to hysteresis, the stable resistance value of the precision resistor helps to smooth the response curve of the entire circuit. When the TMR unit deviates from the ideal response due to hysteresis, the presence of the precision resistor makes the response of the entire circuit more stable and predictable, thereby helping to reduce the error caused by hysteresis.

[0048] Figure 3 Shows a schematic diagram of the circuit connection of the magnetic sensitive unit in a high-precision current sensor according to an embodiment of the present disclosure. Figure 4 Shows a schematic diagram of the circuit connection of the magnetic sensitive unit in another high-precision current sensor according to an embodiment of the present disclosure.

[0049] Such as Figure 3 And Figure 4As shown, the magnetic susceptibility unit includes: an input end, an output end, a TMR Wheatstone bridge, and a precision resistor Wheatstone bridge.

[0050] According to an embodiment of the present disclosure, the TMR Wheatstone bridge includes: a first TMR unit, a second TMR unit, a third TMR unit, and a fourth TMR unit, and the first TMR unit, the second TMR unit, the third TMR unit, and the fourth TMR unit are connected to form the bridge arms of the TMR Wheatstone bridge.

[0051] Specifically, the resistance values of the first TMR unit, the second TMR unit, the third TMR unit, and the fourth TMR unit are R TMR1 , R TMR2 , R TMR3 , R TMR4 . In the case of an ideal magnetic field-free situation, R TMR1 = R TMR2 = R TMR3 = R TMR4 = 0. However, due to the limitations of the manufacturing process and device characteristics of the TMR unit, it is difficult for the TMR units to achieve consistency and have a certain resistance value, that is, R TMR1 ≠ R TMR2 ≠ R TMR3 ≠ R TMR4 ≠ 0, and the values of R TMR1 , R TMR2 , R TMR3 , R TMR4 are close to each other.

[0052] According to an embodiment of the present disclosure, in the TMR Wheatstone bridge, the sensitive directions of the TMR units on adjacent bridge arms are opposite.

[0053] The sensitive direction of the TMR unit refers to the magnetic field direction that causes a significant change in the resistance value of the TMR unit. In the TMR Wheatstone bridge, when the sensitive directions of the TMR units on adjacent bridge arms are opposite, their responses to the same magnetic field direction will cancel each other out. For example, if the external magnetic field direction causes the resistance of one TMR unit to increase, the resistance of another adjacent TMR unit (with the opposite sensitive direction) will decrease accordingly. In this way, the change amounts of the two TMR units cancel each other out in the bridge, making the output of the bridge more stable.

[0054] According to an embodiment of the present disclosure, the precision resistor Wheatstone bridge includes: a first precision resistor, a second precision resistor, a third precision resistor, and a fourth precision resistor with the same resistance value, and the first precision resistor, the second precision resistor, the third precision resistor, and the fourth precision resistor are connected to form the bridge arms of the precision resistor Wheatstone bridge.

[0055] Specifically, the resistance values of the first precision resistor, the second precision resistor, the third precision resistor, and the fourth precision resistor are R1, R2, R3, and R4 respectively, and R1 = R2 = R3 = R4.

[0056] It is known that precision resistors have characteristics such as high stability, high accuracy, and low temperature drift, and the resistance value error of precision resistors is very small. For resistors with a resistance value above 1 ohm, a resistance value error within ±0.5% can be called a precision resistor. Higher-precision precision resistors can reach an accuracy of 0.01%, that is, an error range of one in ten thousand.

[0057] In one implementation, as long as the precision is high enough, it is relatively easy to achieve R1 = R2 = R3 = R4.

[0058] In another implementation, the precision resistor does not need to have an extremely accurate absolute resistance value. As long as the resistance consistency on the four bridge arms is ensured, the matching of the resistance value and temperature drift is better. Since this method has a low requirement for the accuracy of the absolute value of the precision resistor, the manufacturing difficulty of the precision resistor can be greatly reduced.

[0059] According to the embodiments of the present disclosure, the precision resistor generally may include any one of the following: well resistor, diffusion resistor, polysilicon resistor, thin film resistor, metal film resistor, metal foil resistor, wire wound resistor, etc.

[0060] Wherein, the TMR Wheatstone bridge is connected to the precision resistor Wheatstone bridge, such that the first precision resistor is connected in parallel across the two ends of the first TMR unit, the second precision resistor is connected in parallel across the two ends of the second TMR unit, the third precision resistor is connected in parallel across the two ends of the third TMR unit, the fourth precision resistor is connected in parallel across the two ends of the fourth TMR unit, and the TMR Wheatstone bridge and the precision resistor Wheatstone bridge have the same bridge input terminal and bridge output terminal.

[0061] The bridge input terminal is connected to the input terminal and then connected to the power supply, and the bridge output terminal is connected to the output terminal; the resistance value of the precision resistor is less than the resistance value of the TMR unit.

[0062] According to the embodiments of the present disclosure, the ratio of the resistance value of the precision resistor to the resistance value of the TMR unit is within a set ratio range.

[0063] It is known that when there is a zero bias in the TMR unit, that is, there is a certain resistance value even without an externally applied magnetic field, and this resistance value will cause a certain current to flow through. However, when it is connected in parallel with the precision resistor, due to the characteristics of the parallel circuit, part of the current will flow through the precision resistor, thereby reducing the current flowing through the TMR unit, which is equivalent to compensating for the zero bias of the TMR unit.

[0064] The specific ratio of the resistance value of the precision resistor to the resistance value of the TMR unit can be adjusted as needed. For example, the set ratio range is between 1:20 and 1:5. The smaller the set ratio, the better the zero-offset and temperature drift compensation effects. However, it will also affect the sensitivity of the magnetic sensitive unit. Therefore, the ratio range needs to be determined according to the overall accuracy requirements of the high-precision current sensor and the noise and gain of the backend signal processing circuit.

[0065] The present disclosure weakens the zero-offset caused by the mismatch of the resistance values of the TMR units, and also attenuates the temperature drift caused by temperature. Moreover, since the resistance value of the precision resistor is not affected by the magnetic field, the influence brought by the magnetic hysteresis of the TMR element is also greatly reduced, thereby effectively reducing the influence of zero-offset, temperature drift and magnetic hysteresis on the high-precision current sensor.

[0066] At the same time, the present disclosure can not only realize a high-precision current sensor, but also does not need to test the performance of the TMR Wheatstone bridge in each high-precision current sensor. Only by knowing the approximate range of the resistance values of the bridge arms of the TMR Wheatstone bridge can batch compensation be carried out. This is because the existence of the precision resistor Wheatstone bridge reduces the influence brought by the change of the resistance value of the TMR unit. Therefore, only by knowing the approximate range of the resistance values of the bridge arms of the TMR Wheatstone bridge can batch compensation be carried out, thereby realizing mass production.

[0067] The present disclosure also provides a circuit structure, including: a TMR Wheatstone bridge structure and a precision resistor Wheatstone bridge structure; the TMR Wheatstone bridge structure includes 4 TMR units; the precision resistor Wheatstone bridge structure includes 4 precision resistors with the same resistance value; wherein, the TMR Wheatstone bridge structure and the precision resistor Wheatstone bridge structure are connected such that the 4 precision resistors are respectively connected in parallel at both ends of the 4 TMR units, and the TMR Wheatstone bridge structure and the precision resistor Wheatstone bridge structure have the same bridge input end and bridge output end; the resistance value of the precision resistor is less than the resistance value of the TMR unit.

[0068] The present disclosure also provides a chip, including: the high-precision current sensor as described above, or the circuit structure as described above.

[0069] The above description is only the preferred embodiments of the present disclosure and the description of the applied technical principles. Those skilled in the art should understand that the scope of the invention involved in the present disclosure is not limited to the technical solutions formed by the specific combination of the above technical features, but should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the inventive concept. For example, the technical solutions formed by mutually replacing the above features with the (but not limited to) technical features with similar functions disclosed in the present disclosure.

Claims

1. A high-precision current sensor, characterized in that, Comprising: A magnetic susceptibility unit, the magnetic susceptibility unit comprising: an input end, an output end, a tunneling magnetoresistance (TMR) Wheatstone bridge, and a precision resistor Wheatstone bridge; The TMR Wheatstone bridge comprises: a first TMR unit, a second TMR unit, a third TMR unit, and a fourth TMR unit, and the first TMR unit, the second TMR unit, the third TMR unit, and the fourth TMR unit are connected to form the bridge arms of the TMR Wheatstone bridge; The precision resistor Wheatstone bridge comprises: a first precision resistor, a second precision resistor, a third precision resistor, and a fourth precision resistor with the same resistance value, and the first precision resistor, the second precision resistor, the third precision resistor, and the fourth precision resistor are connected to form the bridge arms of the precision resistor Wheatstone bridge; Wherein, the TMR Wheatstone bridge and the precision resistor Wheatstone bridge are connected such that the first precision resistor is connected in parallel across the two ends of the first TMR unit, the second precision resistor is connected in parallel across the two ends of the second TMR unit, the third precision resistor is connected in parallel across the two ends of the third TMR unit, the fourth precision resistor is connected in parallel across the two ends of the fourth TMR unit, and the TMR Wheatstone bridge and the precision resistor Wheatstone bridge have the same bridge input end and bridge output end; The bridge input end is connected to the input end and then connected to a power supply, and the bridge output end is connected to the output end; the resistance value of the precision resistor is less than the resistance value of the TMR unit.

2. The high-precision current sensor according to claim 1, wherein It further comprises: a magnetic core, a coil, a signal processing circuit, and a load resistor; The coil is wound around the magnetic core, the magnetic susceptibility unit is arranged in the opening air gap of the magnetic core, the output end of the magnetic susceptibility unit is connected to the input end of the signal processing circuit, the output end of the signal processing circuit is connected to the first connection terminal of the coil, the second connection terminal of the coil is connected to one end of the load resistor, and the other end of the load resistor is connected to a reference potential.

3. The high-precision current sensor according to claim 2, wherein The signal processing circuit comprises an operational amplifier and a power amplifier; the output end of the magnetic susceptibility unit is connected to the input end of the operational amplifier, the output end of the operational amplifier is connected to the input end of the power amplifier, and the output end of the power amplifier is connected to the first connection terminal of the coil.

4. The high-precision current sensor according to claim 1, wherein The ratio of the resistance value of the precision resistor to the resistance value of the TMR unit is within a set ratio range.

5. The high-precision current sensor according to claim 1, characterized in that, In the TMR Wheatstone bridge, the sensitive directions of the TMR units on adjacent bridge arms are opposite.

6. The high-precision current sensor according to claim 1, wherein The precision resistor comprises any one of the following: well resistor, diffusion resistor, polysilicon resistor, thin film resistor, metal film resistor.

7. A circuit structure, characterized in that, Comprising: A TMR Wheatstone bridge structure and a precision resistor Wheatstone bridge structure; The TMR Wheatstone bridge structure comprises 4 TMR units; The precision resistor Wheatstone bridge structure comprises 4 precision resistors with the same resistance value. Wherein, the TMR Wheatstone bridge structure is connected to the precision resistor Wheatstone bridge structure, such that four precision resistors are respectively connected in parallel at both ends of the four TMR units, and the TMR Wheatstone bridge structure and the precision resistor Wheatstone bridge structure have the same bridge input terminal and bridge output terminal; the resistance value of the precision resistor is less than the resistance value of the TMR unit.

8. A chip, characterized in that, Comprising: The high-precision current sensor according to any one of claims 1 to 6, or the circuit structure according to claim 7.

Images