A current detection system and method based on a TMR sensor

Abstract

The application discloses a current detection system and method based on a TMR sensor, which comprises a ring-shaped iron core with an air gap in a first magnetic field, a first TMR sensor and a second TMR sensor which are placed in parallel in the air gap, a third TMR sensor in a constant magnetic field, a differential amplification system and a data processing system; the first magnetic field is generated by a current to be measured which passes through the center of the ring-shaped iron core, the magnetic field sensitive direction of the first TMR sensor is opposite to that of the second TMR sensor and is the same as the direction of the first magnetic field; the differential amplification system is used for differentially amplifying the output voltages of the three TMR sensors respectively to obtain corresponding voltage data; and the data processing system is used for analyzing all the voltage data and outputting fourth voltage data which can reflect the size of the current to be measured. The application realizes temperature and bias voltage compensation of the TMR sensor without needing to obtain the temperature characteristics and bias characteristics of the TMR sensor.

Description

Technical Field

[0001] This invention relates to the field of TMR sensor power detection, and more particularly to a current detection system and method based on a TMR sensor. Background Technology

[0002] With the deployment and advancement of smart grids and the ubiquitous power Internet of Things, power systems are placing higher demands on current sensing technology. Power systems require the measurement of numerous types of current, and existing single current sensors are insufficient to fully meet the technical requirements of power system current measurement. Tunnel magnetoresistive (TMR) current sensors possess numerous advantages, including high sensitivity, high response frequency, simple structure, and low cost, making them a highly promising product for power system current measurement. However, the sensitivity of TMR sensors is strongly temperature-dependent, significantly impacting measurement accuracy. Furthermore, TMR chips typically employ a bridge structure internally. Due to inherent manufacturing limitations, the initial values ​​of the four internal resistors cannot be guaranteed to be completely identical. Additionally, influenced by surrounding stray magnetic fields, TMR chips have a fixed output bias voltage, which can affect the output results.

[0003] Currently, temperature compensation methods for TMR sensors mainly include hardware compensation and software compensation. Hardware compensation involves connecting components such as thermistors, diodes, and potentiometers with temperature coefficients (TCCs) to the sensor interface circuit. These TCCs have TCCs opposite to the sensor's TCC. Compensation is achieved by first determining the relationship between sensor sensitivity, zero point, and temperature, then selecting different circuit topologies based on the sensitivity-temperature characteristics, and finally calculating and matching the TCCs to achieve temperature compensation. Software compensation, on the other hand, uses regression algorithms in conjunction with a digital sensor microprocessor to fuse the sensor's output signal with the temperature signal to complete the temperature compensation. TMR sensor bias voltage compensation is primarily achieved through hardware compensation. A control circuit with low output impedance and variable output voltage is connected to the reference voltage input of the subsequent instrumentation amplifier. The bias voltage is compensated by adjusting the reference voltage. As can be seen from the above, hardware temperature compensation requires prior knowledge of the TMR sensor's temperature characteristics, and the thermistor's TCC must match the TMR's TCC. Therefore, only one specific thermistor can be matched to one sensor, making it difficult to engineer and mass-produce. Software compensation methods are similar to hardware temperature compensation, also requiring prior knowledge of the sensor's temperature characteristics, making them difficult to engineer and mass-produce. As for bias voltage compensation, it needs to be achieved by connecting a voltage-adjustable control circuit consisting of a controllable resistor and an operational amplifier to the reference voltage input terminal of the subsequent amplification circuit. The bias value needs to be obtained at zero input and the operating point is fixed, that is, compensation can only be obtained at a certain bias value. When the bias value changes with temperature, the bias value cannot be compensated. Summary of the Invention

[0004] This invention provides a current detection system and method based on a TMR sensor, which achieves temperature compensation and bias voltage compensation of the TMR sensor without needing to obtain the temperature and bias characteristics of the TMR sensor, thereby eliminating the influence of temperature and bias voltage on the accuracy of current detection.

[0005] To address the aforementioned technical problems, this invention provides a current detection system based on a TMR sensor, comprising: a toroidal iron core with an air gap, a first TMR sensor and a second TMR sensor placed parallel to each other in the air gap, a third TMR sensor placed in a constant magnetic field outside the toroidal iron core, a differential amplification system, and a data processing system.

[0006] The annular iron core and the air gap of the annular iron core are both in a first magnetic field; the first magnetic field is generated by the current to be measured passing through the center of the annular iron core; the magnetic field sensing direction of the first TMR sensor is the same as the direction of the first magnetic field; and the magnetic field sensing direction of the second TMR sensor is opposite to the direction of the first magnetic field.

[0007] The differential amplification system is used to differentially amplify the output voltage of the first TMR sensor, the output voltage of the second TMR sensor, and the output voltage of the third TMR sensor, respectively, to obtain first voltage data corresponding to the first TMR sensor, second voltage data corresponding to the second TMR sensor, and third voltage data corresponding to the third TMR sensor.

[0008] The data processing system is used to analyze and process the first voltage data, the second voltage data, and the third voltage data according to a preset logical algorithm, and output a fourth voltage data that can reflect the magnitude of the current value of the current to be measured.

[0009] In implementing this embodiment of the invention, a first TMR sensor and a second TMR sensor with opposite magnetic field sensitive directions are placed parallel to each other in the air gap of a toroidal iron core to obtain an output voltage opposite to the direction of the first magnetic field generated by the measured current passing through the center of the toroidal iron core, and an output voltage with the same direction as the first magnetic field. A third TMR sensor is also set up to measure a constant magnetic field to obtain an output voltage corresponding to the constant magnetic field. Then, a differential amplification system is used to differentially amplify and process the output voltages of the three TMR sensors, ultimately outputting a fourth voltage data that reflects the magnitude of the measured current. Through mutual correction of the three TMR sensors, the influence of the TMR sensor bias voltage and the temperature dependence of the TMR sensor sensitivity can be eliminated. This allows the magnitude of the measured current to be directly determined based on the fourth voltage data. This enables temperature compensation and bias voltage compensation of the TMR sensors without needing to obtain their temperature and bias characteristics, improving current detection accuracy and reducing the complexity of the signal processing circuit. This makes the current detection system applicable to TMR current sensing systems with different characteristics.

[0010] As a preferred embodiment, the constant magnetic field is generated by a permanent magnet; wherein both the permanent magnet and the third TMR sensor are placed in a magnetic shielding shell.

[0011] In a preferred embodiment of the present invention, a constant magnetic field is provided by a permanent magnet, and both the permanent magnet and the third TMR sensor are placed in a magnetic shielding shell to magnetically shield the constant magnetic field, as well as the permanent magnet and the third TMR sensor in the constant magnetic field, in order to avoid the influence of other stray magnetic fields and further eliminate the influence of the TMR sensor bias voltage.

[0012] As a preferred embodiment, the differential amplifier system includes: a first differential amplifier, a second differential amplifier, and a third differential amplifier;

[0013] The first differential amplifier is connected to the signal output terminal of the first TMR sensor and is used to differentially amplify the output voltage of the first TMR sensor with a gain of a first preset value to obtain the first voltage data corresponding to the first TMR sensor.

[0014] The second differential amplifier is connected to the signal output terminal of the second TMR sensor and is used to differentially amplify the output voltage of the second TMR sensor with a gain of the first preset value to obtain the second voltage data corresponding to the second TMR sensor.

[0015] The third differential amplifier is connected to the signal output terminal of the third TMR sensor and is used to differentially amplify the output voltage of the third TMR sensor with a gain of a second preset value to obtain the third voltage data corresponding to the third TMR sensor.

[0016] Wherein, the first preset value is equal to half of the second preset value.

[0017] In a preferred embodiment of the present invention, a first differential amplifier and a second differential amplifier are used to differentially amplify the output voltages of the first TMR sensor and the second TMR sensor with a gain of a first preset value, respectively. A third differential amplifier is used to differentially amplify the output voltage of the third TMR sensor with a gain of twice the first preset value. This improves the strength and clarity of the output voltage signal and suppresses noise in the output voltage signal. This facilitates the accurate derivation of a fourth voltage data that reflects the magnitude of the current value to be measured, based on the calculation results of the first voltage data output by the first differential amplifier, the second voltage data output by the second differential amplifier, and the third voltage data output by the third differential amplifier.

[0018] As a preferred embodiment, the data processing system includes: a first subtractor, an adder, a second subtractor, and a divider;

[0019] The first subtractor is used to subtract the first voltage data from the second voltage data to obtain a corresponding first calculation result, and then transmit the first calculation result to the divider.

[0020] The adder is used to add the first voltage data and the second voltage data to obtain the corresponding second operation result, and transmit the second operation result to the second subtractor;

[0021] The second subtractor is used to subtract the third voltage data from the second calculation result to obtain the corresponding third calculation result, and then transmit the third calculation result to the divider.

[0022] The divider is used to divide the first calculation result by the third calculation result to obtain the fourth voltage data.

[0023] In a preferred embodiment of the present invention, the differential amplification results of the output voltages of the first TMR sensor, the second TMR sensor, and the third TMR sensor are processed by a first subtractor, an adder, a second subtractor, and a divider to obtain a voltage signal that is proportional to the magnitude of the current to be measured, so that the magnitude of the current to be measured can be directly known based on the fourth voltage data.

[0024] To address the same technical problem, embodiments of the present invention also provide a current detection method based on a TMR sensor, comprising:

[0025] When the current to be measured passes through the center of the toroidal iron core with an air gap, the first magnetic field generated by the current to be measured is detected by the first TMR sensor and the second TMR sensor respectively, and the output voltage of the first TMR sensor and the output voltage of the second TMR sensor are obtained. Then, the constant magnetic field is detected by the third TMR sensor, and the output voltage of the third TMR sensor is obtained.

[0026] The output voltages of the first TMR sensor, the second TMR sensor, and the third TMR sensor are differentially amplified using a differential amplification system to obtain first voltage data corresponding to the first TMR sensor, second voltage data corresponding to the second TMR sensor, and third voltage data corresponding to the third TMR sensor.

[0027] According to a preset logic algorithm, the first voltage data, the second voltage data, and the third voltage data are analyzed and processed, and a fourth voltage data that can reflect the magnitude of the current value of the current to be measured is output.

[0028] The first TMR sensor and the second TMR sensor are placed parallel to each other in the air gap of the annular iron core. The magnetic field sensing direction of the first TMR sensor is the same as the direction of the first magnetic field, and the magnetic field sensing direction of the second TMR sensor is opposite to the direction of the first magnetic field. The annular iron core and the air gap of the annular iron core are both in the first magnetic field. The third TMR sensor is placed in the constant magnetic field outside the annular iron core.

[0029] As a preferred embodiment, the constant magnetic field is generated by a permanent magnet; wherein both the permanent magnet and the third TMR sensor are placed in a magnetic shielding shell.

[0030] As a preferred embodiment, the differential amplification system is used to differentially amplify the output voltages of the first TMR sensor, the second TMR sensor, and the third TMR sensor, respectively, to obtain first voltage data corresponding to the first TMR sensor, second voltage data corresponding to the second TMR sensor, and third voltage data corresponding to the third TMR sensor. Specifically:

[0031] Using the first differential amplifier in the differential amplification system, the output voltage of the first TMR sensor is differentially amplified with a gain of a first preset value to obtain the first voltage data corresponding to the first TMR sensor.

[0032] Using the second differential amplifier in the differential amplifier system, the output voltage of the second TMR sensor is differentially amplified with a gain of the first preset value to obtain the second voltage data corresponding to the second TMR sensor.

[0033] Using the third differential amplifier in the differential amplifier system, the output voltage of the third TMR sensor is differentially amplified with a gain of a second preset value to obtain the third voltage data corresponding to the third TMR sensor.

[0034] Wherein, the first preset value is equal to half of the second preset value, the first differential amplifier is connected to the signal output terminal of the first TMR sensor, the second differential amplifier is connected to the signal output terminal of the second TMR sensor, and the third differential amplifier is connected to the signal output terminal of the third TMR sensor.

[0035] As a preferred embodiment, the first voltage data, the second voltage data, and the third voltage data are analyzed and processed according to a preset logic algorithm, and a fourth voltage data that reflects the magnitude of the current value to be measured is output, specifically as follows:

[0036] Subtract the first voltage data from the second voltage data to obtain the corresponding first calculation result, and add the first voltage data to the second voltage data to obtain the corresponding second calculation result;

[0037] Subtract the third voltage data from the second calculation result to obtain the corresponding third calculation result, and divide the first calculation result by the third calculation result to obtain the fourth voltage data. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of a current detection system based on a TMR sensor provided in Embodiment 1 of the present invention;

[0039] Figure 2 This is a schematic flowchart of a current detection method based on a TMR sensor provided in Embodiment 1 of the present invention. Detailed Implementation

[0040] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0041] Example 1:

[0042] Please refer to Figure 1 The diagram below illustrates the structure of a current detection system based on a TMR sensor, as provided in an embodiment of the present invention. The system includes: a toroidal iron core 1 with an air gap, a first TMR sensor 2 and a second TMR sensor 3 placed parallel to each other in the air gap, a third TMR sensor 4 placed in a constant magnetic field B0 outside the toroidal iron core 1, a differential amplification system 5, and a data processing system 6.

[0043] As a preferred embodiment, the constant magnetic field B0 is generated by a permanent magnet; wherein the permanent magnet and the third TMR sensor 4 are both placed in a magnetic shielding shell 7, which is made of a high magnetic permeability material, so that the permanent magnet and the third TMR sensor 4 within the constant magnetic field B0 are not affected by other stray magnetic fields from the outside.

[0044] Based on the working characteristics of the TMR sensor, the mathematical relationship between the output voltage of the TMR sensor and its magnetic field can be found in Equation (1).

[0045] U=k(T)BV in +b0 (1)

[0046] In the formula, U represents the output voltage of the TMR sensor; k(T) represents the sensitivity of the TMR sensor, which varies with temperature T; B represents the magnetic field in which the TMR sensor is located; V in b0 represents the power supply voltage of the TMR sensor; b0 represents the zero-point bias voltage of the TMR sensor.

[0047] In this embodiment, both the toroidal core 1 and the air gap of the toroidal core 1 are within the first magnetic field B1; wherein, the first magnetic field B1 is the measured current I passing through the center of the toroidal core 1. P The magnetic field sensing direction of the first TMR sensor 2 is the same as that of the first magnetic field B1, while the magnetic field sensing direction of the second TMR sensor 3 is opposite to that of the first magnetic field B1.

[0048] In this embodiment, the first TMR sensor 2, the second TMR sensor 3, and the third TMR sensor 4 are products of the same model and batch, and these three TMR sensors are powered by the same power supply. Therefore, the sensitivity, power supply voltage, and zero-point bias voltage of the first TMR sensor 2, the second TMR sensor 3, and the third TMR sensor 4 are all the same. Based on the operating characteristics of TMR sensors, the output voltage U of the first TMR sensor 2 is... 10 Please refer to equation (2) for the expression, where U is the output voltage of the second TMR sensor 3. 20Please refer to equation (3) for the expression, and the expression for the output voltage U of the third TMR sensor 4. 00 Please refer to equation (4).

[0049] U 10 =k1(T)B1V in +b0 (2)

[0050] U 20 =-k2(T)B1V in +b0 (3)

[0051] U 00 =k3(T)B0V in +b0 (4)

[0052] In the formula, K1(T) represents the sensitivity of the first TMR sensor, which varies with temperature T; K2(T) represents the sensitivity of the second TMR sensor, which varies with temperature T; K3(T) represents the sensitivity of the third TMR sensor, which varies with temperature T; and B1 represents the measured current I passing through the center of the toroidal core 1. P The generated first magnetic field; B0 represents the constant magnetic field at which the third TMR sensor 4 is located; V in The voltages represent the supply voltages of the first TMR sensor 2, the second TMR sensor 3, and the third TMR sensor 4; b0 represents the zero-point bias voltage of the first TMR sensor 2, the second TMR sensor 3, and the third TMR sensor 4. Where k1(T) = k2(T) = k3(T).

[0053] Differential amplifier system 5 is used to respectively amplify the output voltage U of the first TMR sensor 2. 10 The output voltage U of the second TMR sensor 3 20 and the output voltage U of the third TMR sensor 4 00 Differential amplification is performed to obtain the first voltage data U corresponding to the first TMR sensor 2. 11 The second voltage data U corresponding to the second TMR sensor 3 21 The third voltage data U corresponding to the third TMR sensor 4 01 .

[0054] For the preferred option, please refer to Figure 1 The differential amplifier system 5 includes: a first differential amplifier 501, a second differential amplifier 502, and a third differential amplifier 503, the specific components of which are as follows:

[0055] The first differential amplifier 501 is connected to the signal output terminal of the first TMR sensor 2, and is used to control the output voltage U of the first TMR sensor 2 (see equation (5)). 10Differential amplification with a gain of the first preset value K is performed to obtain the first voltage data U corresponding to the first TMR sensor 2. 11 .

[0056] U 11 =K[k(T)B1V in +b0] (5)

[0057] The second differential amplifier 502 is connected to the signal output terminal of the second TMR sensor 3, and is used to control the output voltage U of the second TMR sensor 3 (see equation (6)). 20 Differential amplification with a gain of the first preset value K is performed to obtain the second voltage data U corresponding to the second TMR sensor 3. 21 .

[0058] U 21 =K[k(T)B1V in +b0] (6)

[0059] The third differential amplifier 503 is connected to the signal output terminal of the third TMR sensor 4, and is used to control the output voltage U of the third TMR sensor 4 (see equation (7)). 00 Differential amplification with a gain of 2K is performed to obtain the third voltage data U corresponding to the third TMR sensor 4. 01 .

[0060] U 01 =2K[k(T)B0V in +b0] (7)

[0061] Data processing system 6 is used to process the first voltage data U according to a preset logic algorithm. 11 Second voltage data U 21 and the third voltage data U 01 The system performs analysis and processing, and outputs a value that reflects the measured current I. P The fourth voltage data U of the current value out .

[0062] For the preferred option, please refer to Figure 1 The data processing system 6 includes: a first subtractor 601, an adder 602, a second subtractor 603, and a divider 604, the specific components of which are as follows:

[0063] The first subtractor 601, as shown in equation (8), is used to subtract the first voltage data U. 11 With the second voltage data U 21 Subtracting them yields the corresponding first result U. 12 and the first calculation result U 12 Transmitted to divider 604.

[0064] U 12 =U 11 -U 21 =K·k(T)B1V in (8)

[0065] Adder 602, used in equation (9), converts the first voltage data U 11 With the second voltage data U 21 Add them together to get the corresponding second operation result U. 22 and the second operation result U 22 Transmitted to the second subtractor 603.

[0066] U 22 =U 11 +U 21 =2Kb0 (9)

[0067] The second subtractor 603, as shown in equation (10), is used to subtract the third voltage data U. 01 With the second operation result U 22 Subtracting the two results yields the corresponding third operation result U. 02 and the third operation result U 02 Transmitted to divider 604.

[0068] U 02 =U 01 -U 22 =2K·k(T)B0V in (10)

[0069] Divider 604, used in equation (11), divides the first operation result U 12 Divide by the result of the third operation U 02 The fourth voltage data U is obtained. out .

[0070]

[0071] It should be noted that, based on equation (11), the final output U of the system is... out It does not contain a bias voltage b0 and is independent of temperature T, only related to the current I being measured. P The generated first magnetic field B1 is proportional to the magnetic field, while B0 is a constant magnetic field generated by the permanent magnet. Therefore, the current detection system based on a TMR sensor provided in this embodiment of the invention eliminates the influence of bias voltage and also eliminates the influence of the temperature dependence of TMR chip sensitivity.

[0072] Please refer to Figure 2This is a flowchart illustrating a current detection method based on a TMR sensor provided in an embodiment of the present invention. The method includes steps S1 to S3, and the specific details of each step are as follows:

[0073] Step S1: When the current to be measured passes through the center of the annular iron core with an air gap, the first magnetic field generated by the current to be measured is detected by the first TMR sensor and the second TMR sensor respectively, and the output voltage of the first TMR sensor and the output voltage of the second TMR sensor are obtained. Then, the constant magnetic field is detected by the third TMR sensor, and the output voltage of the third TMR sensor is obtained.

[0074] The first TMR sensor and the second TMR sensor are placed parallel to each other in the air gap of the toroidal iron core. The magnetic field sensing direction of the first TMR sensor is the same as the direction of the first magnetic field, and the magnetic field sensing direction of the second TMR sensor is opposite to the direction of the first magnetic field. The toroidal iron core and the air gap of the toroidal iron core are both in the first magnetic field. The third TMR sensor is placed in a constant magnetic field outside the toroidal iron core.

[0075] As a preferred option, the constant magnetic field is generated by a permanent magnet; both the permanent magnet and the third TMR sensor are placed in a magnetic shielding shell.

[0076] Step S2: The output voltages of the first TMR sensor, the second TMR sensor, and the third TMR sensor are differentially amplified by a differential amplification system to obtain the first voltage data corresponding to the first TMR sensor, the second voltage data corresponding to the second TMR sensor, and the third voltage data corresponding to the third TMR sensor.

[0077] As a preferred embodiment, step S2 includes steps S21 to S23, each of which is detailed below:

[0078] Step S21: Using the first differential amplifier in the differential amplifier system, the output voltage of the first TMR sensor is differentially amplified with a gain of a first preset value to obtain the first voltage data corresponding to the first TMR sensor.

[0079] Step S22: Using the second differential amplifier in the differential amplifier system, the output voltage of the second TMR sensor is differentially amplified with a gain of the first preset value to obtain the second voltage data corresponding to the second TMR sensor.

[0080] Step S23: Using the third differential amplifier in the differential amplifier system, the output voltage of the third TMR sensor is differentially amplified with a gain of the second preset value to obtain the third voltage data corresponding to the third TMR sensor.

[0081] Wherein, the first preset value is equal to half of the second preset value, the first differential amplifier is connected to the signal output terminal of the first TMR sensor, the second differential amplifier is connected to the signal output terminal of the second TMR sensor, and the third differential amplifier is connected to the signal output terminal of the third TMR sensor.

[0082] Step S3: According to the preset logic algorithm, analyze and process the first voltage data, the second voltage data and the third voltage data, and output the fourth voltage data that can reflect the magnitude of the current value of the current to be measured.

[0083] As a preferred embodiment, step S3 includes steps S31 to S32, each of which is detailed below:

[0084] Step S31: Subtract the first voltage data from the second voltage data to obtain the corresponding first calculation result, and add the first voltage data to the second voltage data to obtain the corresponding second calculation result.

[0085] Step S32: Subtract the third voltage data from the second calculation result to obtain the corresponding third calculation result, and divide the first calculation result by the third calculation result to obtain the fourth voltage data.

[0086] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working process of the method described above can be referred to the corresponding process in the aforementioned system embodiments, and will not be repeated here.

[0087] Compared with the prior art, the embodiments of the present invention have the following beneficial effects:

[0088] This invention provides a current detection system and method based on a TMR sensor. A first TMR sensor and a second TMR sensor with opposite magnetic field sensitivity directions are placed in the air gap of a toroidal core, and the first and second TMR sensors are parallel to each other. This obtains an output voltage opposite to the direction of the first magnetic field generated by the measured current passing through the center of the toroidal core, and an output voltage in the same direction as the first magnetic field. A third TMR sensor is additionally set to measure a constant magnetic field, obtaining an output voltage corresponding to the constant magnetic field. Then, a differential amplification system is used to differentially amplify and process the output voltages of the three TMR sensors, ultimately outputting a fourth voltage data that reflects the magnitude of the measured current. Through mutual correction of the three TMR sensors, the influence of the TMR sensor bias voltage and the temperature dependence of the TMR sensor sensitivity are eliminated. This allows the magnitude of the measured current to be directly determined based on the fourth voltage data. Essentially, temperature compensation and bias voltage compensation of the TMR sensor can be achieved without acquiring the temperature and bias characteristics of the TMR sensor, improving current detection accuracy and reducing the complexity of the signal processing circuit. This makes the current detection system applicable to TMR current sensing systems with different characteristics.

[0089] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the scope of protection of the present invention. In particular, it should be noted that any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention for those skilled in the art.

Claims

1. A current detection system based on a TMR sensor, characterized in that, include: The system includes an annular iron core with an air gap, a first TMR sensor and a second TMR sensor placed parallel to each other in the air gap, a third TMR sensor placed in a constant magnetic field outside the annular iron core, a differential amplification system, and a data processing system. The data processing system includes: a first subtractor, an adder, a second subtractor, and a divider; The annular iron core and the air gap of the annular iron core are both in a first magnetic field; the first magnetic field is generated by the current to be measured passing through the center of the annular iron core; the magnetic field sensing direction of the first TMR sensor is the same as the direction of the first magnetic field; and the magnetic field sensing direction of the second TMR sensor is opposite to the direction of the first magnetic field. The differential amplification system is used to differentially amplify the output voltage of the first TMR sensor, the output voltage of the second TMR sensor, and the output voltage of the third TMR sensor, respectively, to obtain first voltage data corresponding to the first TMR sensor, second voltage data corresponding to the second TMR sensor, and third voltage data corresponding to the third TMR sensor. The data processing system is used to analyze and process the first voltage data, the second voltage data and the third voltage data according to a preset logical algorithm, and output a fourth voltage data that can reflect the magnitude of the current value of the current to be measured. The first subtractor is used to subtract the first voltage data from the second voltage data to obtain a corresponding first calculation result, and then transmit the first calculation result to the divider. The adder is used to add the first voltage data and the second voltage data to obtain the corresponding second operation result, and transmit the second operation result to the second subtractor; The second subtractor is used to subtract the third voltage data from the second calculation result to obtain the corresponding third calculation result, and then transmit the third calculation result to the divider. The divider is used to divide the first calculation result by the third calculation result to obtain the fourth voltage data.

2. The current detection system based on a TMR sensor according to claim 1, characterized in that, The constant magnetic field is generated by a permanent magnet; both the permanent magnet and the third TMR sensor are placed in a magnetic shielding shell.

3. The current detection system based on a TMR sensor according to claim 1, characterized in that, The differential amplifier system includes: a first differential amplifier, a second differential amplifier, and a third differential amplifier; The first differential amplifier is connected to the signal output terminal of the first TMR sensor and is used to differentially amplify the output voltage of the first TMR sensor with a gain of a first preset value to obtain the first voltage data corresponding to the first TMR sensor. The second differential amplifier is connected to the signal output terminal of the second TMR sensor and is used to differentially amplify the output voltage of the second TMR sensor with a gain of the first preset value to obtain the second voltage data corresponding to the second TMR sensor. The third differential amplifier is connected to the signal output terminal of the third TMR sensor and is used to differentially amplify the output voltage of the third TMR sensor with a gain of a second preset value to obtain the third voltage data corresponding to the third TMR sensor. Wherein, the first preset value is equal to half of the second preset value.

4. A current detection method based on a TMR sensor, characterized in that, include: When the current to be measured passes through the center of the toroidal iron core with an air gap, the first magnetic field generated by the current to be measured is detected by the first TMR sensor and the second TMR sensor respectively, and the output voltage of the first TMR sensor and the output voltage of the second TMR sensor are obtained. Then, the constant magnetic field is detected by the third TMR sensor, and the output voltage of the third TMR sensor is obtained. The output voltages of the first TMR sensor, the second TMR sensor, and the third TMR sensor are differentially amplified using a differential amplification system to obtain first voltage data corresponding to the first TMR sensor, second voltage data corresponding to the second TMR sensor, and third voltage data corresponding to the third TMR sensor. According to a preset logic algorithm, the first voltage data, the second voltage data, and the third voltage data are analyzed and processed, and a fourth voltage data that can reflect the magnitude of the current value of the current to be measured is output. The first TMR sensor and the second TMR sensor are placed parallel to each other in the air gap of the annular iron core. The magnetic field sensing direction of the first TMR sensor is the same as the direction of the first magnetic field, and the magnetic field sensing direction of the second TMR sensor is opposite to the direction of the first magnetic field. The annular iron core and the air gap of the annular iron core are both in the first magnetic field. The third TMR sensor is placed in the constant magnetic field outside the annular iron core. The first voltage data, the second voltage data, and the third voltage data are analyzed and processed according to a preset logic algorithm, and a fourth voltage data that reflects the magnitude of the current value to be measured is output. Specifically: Subtract the first voltage data from the second voltage data to obtain the corresponding first calculation result, and add the first voltage data to the second voltage data to obtain the corresponding second calculation result; Subtract the third voltage data from the second calculation result to obtain the corresponding third calculation result, and divide the first calculation result by the third calculation result to obtain the fourth voltage data.

5. The current detection method based on a TMR sensor according to claim 4, characterized in that, The constant magnetic field is generated by a permanent magnet; both the permanent magnet and the third TMR sensor are placed in a magnetic shielding shell.

6. The current detection method based on a TMR sensor according to claim 4, characterized in that, The differential amplification system differentially amplifies the output voltages of the first TMR sensor, the second TMR sensor, and the third TMR sensor to obtain first voltage data corresponding to the first TMR sensor, second voltage data corresponding to the second TMR sensor, and third voltage data corresponding to the third TMR sensor. Specifically: Using the first differential amplifier in the differential amplification system, the output voltage of the first TMR sensor is differentially amplified with a gain of a first preset value to obtain the first voltage data corresponding to the first TMR sensor. Using the second differential amplifier in the differential amplifier system, the output voltage of the second TMR sensor is differentially amplified with a gain of the first preset value to obtain the second voltage data corresponding to the second TMR sensor. Using the third differential amplifier in the differential amplifier system, the output voltage of the third TMR sensor is differentially amplified with a gain of a second preset value to obtain the third voltage data corresponding to the third TMR sensor. Wherein, the first preset value is equal to half of the second preset value, the first differential amplifier is connected to the signal output terminal of the first TMR sensor, the second differential amplifier is connected to the signal output terminal of the second TMR sensor, and the third differential amplifier is connected to the signal output terminal of the third TMR sensor.

Images