A current sensor and a current detection method based on a TMR chip

Abstract

The application discloses a current sensor and a current detection method based on a TMR chip, and comprises the TMR chip which is placed in the air gap of a ring-shaped iron core and is used for generating a first voltage signal; a first magnetic field is generated by a to-be-detected current passing through the center of the ring-shaped iron core, and a second magnetic field is generated by a coil through which a reference current passes; a reference current generation circuit is used for generating a reference current with a frequency different from that of the to-be-detected current; a differential amplification circuit is used for differentially amplifying the first voltage signal to obtain a second voltage signal; and a signal analysis processing module is used for performing DFT analysis on the second voltage signal to obtain a main direct current voltage component, a reference voltage component and a plurality of alternating current voltage components, then performing division operation on the main direct current voltage component and the reference voltage component to obtain voltage data capable of reflecting the current value of the to-be-detected current. The application realizes temperature compensation of the TMR chip without knowing the temperature characteristics of the sensitivity of the TMR chip.

Description

Technical Field

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

[0002] With the development of DC transmission systems and the utilization of new energy sources, DC current measurement is crucial for power metering and system protection. DC current measurement systems based on the TMR magnetoresistive effect have advantages such as simple structure, non-contact operation with the measured line, and wide measurement bandwidth, and are gradually becoming a research hotspot. These systems utilize a toroidal iron core with an air gap as a magnetic ring, placing the TMR chip within the air gap. The TMR chip outputs a voltage signal proportional to the measured current, thus enabling the measurement of the line current.

[0003] The performance of current measurement systems based on the TMR magnetoresistive effect primarily depends on the characteristics of the TMR chip. While the nonlinearity error of TMR chips can be controlled within 0.1% of their measurement range due to material limitations, the temperature dependence of TMR sensitivity remains high. The lowest temperature dependence of commercially available TMR chips is still several hundred ppm / ℃, making it difficult for current measurement systems to meet metrological requirements in power grid applications. Currently, research institutions have proposed two main methods to compensate for this temperature dependence: one is to use a thermistor to generate a power supply with temperature characteristics as the TMR chip's supply voltage, thus canceling out the temperature dependence of the sensitivity; the other method involves measuring temperature parameters, creating a table of the TMR's temperature characteristics, and then performing temperature compensation in software by looking up the table. Both of these temperature compensation methods have some effectiveness, but also their limitations. The first method, which uses the temperature characteristics of a thermistor to change the supply voltage of a TMR chip, requires a perfect match between the thermistor's temperature characteristics and the TMR chip's sensitivity temperature dependence. However, the sensitivity temperature dependence of TMR chips is variable, meaning that each TMR chip requires a different thermistor to achieve good temperature compensation, making this method uncommon. The second method, using software compensation, requires obtaining the TMR chip's temperature characteristics experimentally and then embedding them into the software. Due to the variability of each TMR chip, temperature characteristic tests need to be performed on each individual chip, thus this method also lacks universality. Summary of the Invention

[0004] This invention provides a current sensor and current detection method based on a TMR chip, which can detect the current to be measured without knowing the sensitivity temperature characteristics of the TMR chip, thereby eliminating the influence of the TMR chip and temperature on the accuracy and efficiency of current detection.

[0005] To address the aforementioned technical problems, this invention provides a current sensor based on a TMR chip, comprising: a toroidal core with an air gap, a TMR chip placed in the air gap, a reference current generation circuit, a coil wound on the TMR chip, a differential amplifier circuit, and a signal analysis and processing module. The TMR chip is positioned in a first magnetic field and a second magnetic field with the same direction, and is used to generate a first voltage signal based on the first magnetic field and the second magnetic field; the first magnetic field is generated by the current to be measured passing through the center of the toroidal iron core, and the second magnetic field is generated by the reference current when a reference current is applied to the coil; The reference current generation circuit is used to generate the reference current; the frequency of the reference current is different from the frequency of the current to be measured. The differential amplifier circuit is used to differentially amplify the first voltage signal output by the TMR chip to obtain a second voltage signal. The signal analysis and processing module is used to perform DFT analysis on the second voltage signal output by the differential amplifier circuit to obtain the main DC voltage component, reference voltage component and multiple AC voltage components corresponding to the second voltage signal. Then, the main DC voltage component and the reference voltage component are divided to obtain and output voltage data that can reflect the magnitude of the current value of the current to be measured.

[0006] In implementing this embodiment of the invention, when the current to be measured passes through the center of the toroidal core with an air gap, a first magnetic field is generated by the current to be measured, so that the TMR chip placed in the air gap is in the first magnetic field. At the same time, a reference current with a different frequency than the current to be measured is generated by the reference current generation circuit, so that the signal can be separated by DFT analysis in the signal analysis and processing module. The reference current is passed into the coil wound on the TMR chip, and the coil generates a second magnetic field corresponding to the reference current, so that the TMR chip is in the second magnetic field. This realizes that the first magnetic field corresponding to the current to be measured and the second magnetic field corresponding to the reference current are applied to the TMR chip at the same time, so that the TMR chip outputs a first voltage signal associated with the first magnetic field and the second magnetic field. Then, the first voltage signal is differentially amplified so that the amplified second voltage signal can be subjected to DFT analysis, thereby separating the second voltage signal into the corresponding main DC voltage component, the reference voltage component, and multiple AC voltage components. Since the main DC voltage component and the reference voltage component, apart from the differential amplification gain and the sensitivity of the TMR chip, are only related to the conversion coefficient between the current and the magnetic field, the main DC component in the measured current, and the reference current, by performing a division operation on the main DC voltage component and the reference voltage component, we can obtain a calculation result that is only related to the conversion coefficient between the current and the magnetic field, the main DC component in the measured current, and the reference current, and is independent of the sensitivity of the TMR chip, thus realizing the compensation of the temperature dependence of the current sensor on the sensitivity of the TMR chip.

[0007] As a preferred embodiment, the reference current generation circuit specifically includes: a digital-to-analog converter and a voltage-controlled current source; The digital-to-analog converter is connected to the microcontroller unit in the signal analysis and processing module, and is used to perform D / A digital-to-analog conversion on the reference voltage signal output by the microcontroller unit to obtain the analog signal corresponding to the reference voltage signal; The voltage-controlled current source is connected to the digital-to-analog converter and is used to convert the analog signal into the corresponding reference current.

[0008] In a preferred embodiment of the present invention, the known reference voltage signal output by the microcontroller unit is converted from digital to analog (D / A) for signal transmission. Then, a voltage-controlled current source is used to convert the analog signal, thereby providing a highly stable reference current for the coil wound on the TMR chip.

[0009] As a preferred embodiment, the signal analysis and processing module specifically includes: an analog-to-digital converter and a microcontroller unit; The analog-to-digital converter is connected to the differential amplifier circuit and is used to perform A / D conversion on the second voltage signal output by the differential amplifier circuit to obtain the digital signal corresponding to the second voltage signal. The microcontroller unit, connected to the analog-to-digital converter, is used to perform DFT analysis on the digital signal to obtain the main DC voltage component, the reference voltage component, and multiple AC voltage components corresponding to the second voltage signal. The main DC voltage component and the reference voltage component are then divided to obtain and output voltage data that reflects the magnitude of the current value of the current to be measured.

[0010] In a preferred embodiment of the present invention, the second voltage signal output by the differential amplifier circuit is subjected to A / D analog-to-digital conversion so that the microcontroller unit can perform calculation and analysis. Thus, through DFT analysis of the digital signal, the main DC voltage component, the reference voltage component, and multiple AC voltage components corresponding to the second voltage signal are obtained.

[0011] As a preferred embodiment, the winding direction of the coil is perpendicular to the magnetic field sensitive direction of the TMR chip, and the magnetic field sensitive direction of the TMR chip is the same as the direction of the first magnetic field.

[0012] In a preferred embodiment of the present invention, since the winding direction of the coil is perpendicular to the magnetic field sensitive direction of the TMR chip, when a reference current is applied to the coil, the direction of the second magnetic field generated by the coil is parallel to the magnetic field sensitive direction of the TMR chip. The direction of the first magnetic field generated by the current to be measured passing through the toroidal core with an air gap is also parallel to the magnetic field sensitive direction of the TMR chip. Therefore, the directions of the first magnetic field and the second magnetic field are the same, and it can be directly known that the total magnetic field applied to the TMR chip is a simple superposition of the first magnetic field and the second magnetic field, thereby simplifying the analysis of the relationship between the output voltage of the TMR chip and the first and second magnetic fields.

[0013] To address the same technical problem, embodiments of the present invention also provide a current detection method based on a TMR chip, comprising: When the current to be measured passes through the center of the toroidal iron core with an air gap, a first voltage signal is generated based on the first magnetic field and the second magnetic field generated by the current to be measured. The first voltage signal output by the TMR chip placed in the air gap is differentially amplified to obtain a second voltage signal. The second voltage signal is then subjected to DFT analysis to obtain the main DC voltage component, the reference voltage component, and multiple AC voltage components corresponding to the second voltage signal. The main DC voltage component and the reference voltage component are then divided to output voltage data that can reflect the magnitude of the current value of the current to be measured. Wherein, the direction of the first magnetic field is the same as the direction of the second magnetic field, and the second magnetic field is generated by the reference current when a reference current is passed through the coil wound on the TMR chip. The reference current is generated by the reference current generation circuit, and the frequency of the reference current is different from the frequency of the current to be measured.

[0014] As a preferred embodiment, the generation of the reference current is specifically as follows: The reference voltage signal output by the microcontroller unit is subjected to D / A digital-to-analog conversion to obtain the analog signal corresponding to the reference voltage signal; The analog signal is converted into the corresponding reference current using a voltage-controlled current source; The frequency of the reference voltage signal is different from the frequency of the current to be measured.

[0015] As a preferred embodiment, the step of performing DFT analysis on the second voltage signal to output voltage data that reflects the magnitude of the current value to be measured specifically involves: The second voltage signal is converted from analog to digital by an A / D converter to obtain the digital signal corresponding to the second voltage signal; The digital signal is subjected to DFT analysis to obtain the main DC voltage component, the reference voltage component, and multiple AC voltage components corresponding to the second voltage signal. The main DC voltage component and the reference voltage component are divided to obtain and output voltage data that can reflect the magnitude of the current value of the current to be measured.

[0016] As a preferred embodiment, the winding direction of the coil is perpendicular to the magnetic field sensitive direction of the TMR chip, and the magnetic field sensitive direction of the TMR chip is the same as the direction of the first magnetic field. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of a current sensor based on a TMR chip provided in Embodiment 1 of the present invention. Figure 2 : This is a schematic diagram of the magnetic field superposition principle of a TMR chip in a current sensor based on a TMR chip, provided in Embodiment 1 of the present invention; Figure 3 This is a flowchart illustrating a current detection method based on a TMR chip provided in Embodiment 1 of the present invention. Detailed Implementation

[0018] 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.

[0019] Example 1: Please refer to Figure 1 This is a schematic diagram of a current sensor based on a TMR chip, provided by an embodiment of the present invention. The current sensor includes: a toroidal iron core 1 with an air gap, a TMR chip 2 placed in the air gap, a reference current generation circuit 3, an N-turn coil 4 wound on the TMR chip 2, a differential amplifier circuit 5, and a signal analysis and processing module 6. The specific functions and arrangements of each structure / component are as follows: It should be noted that the air gap refers to the part that has been cut open on the toroidal iron core 1.

[0020] Reference current generation circuit 3 is used to generate a reference current. .

[0021] Among them, the frequency of the reference current The current to be measured passing through the center of the toroidal core 1 The frequencies are different.

[0022] It should be noted that in a DC power grid, the current to be measured includes the main DC current and various harmonic currents. The frequency components of the harmonic current are generally integers of the power frequency. Therefore, please refer to equation (1) for the expression of the current to be measured, and please refer to equation (2) for the expression of the reference current flowing through coil 4.

[0023] （1） （2） In the formula, Indicates the main DC component; This indicates an alternating current component containing all harmonics; Indicates power frequency; The frequency of the reference current is indicated, and .

[0024] Preferably, the reference current generation circuit 3 specifically includes: a digital-to-analog converter 31 and a voltage-controlled current source 32; wherein the functions and arrangements of each structure / component are as follows: The digital-to-analog converter 31 is connected to the microcontroller unit (MCU) in the signal analysis and processing module 6. It performs a digital-to-analog (D / A) conversion on the reference voltage signal output by the MCU to obtain an analog signal corresponding to the reference voltage signal. The frequency of the reference voltage signal is related to the measured current. The frequencies are different.

[0025] The voltage-controlled current source 32 is connected to the digital-to-analog converter 31 and is used to convert the analog signal into a corresponding reference current. and reference current The input is given to the N-turn coil 4 wound on the TMR chip 2, so that the TMR chip 2 is in a state controlled by the reference current. The generated second magnetic field superior.

[0026] TMR chip 2 is in the same direction as the first magnetic field. Second magnetic field In, used according to the first magnetic field Second magnetic field Generate the first voltage signal .

[0027] In this embodiment, the first magnetic field The current to be measured is the current passing through the center of the toroidal iron core 1. The generated first magnetic field With the current to be measured Proportional, its expression can be found in equation (3), the second magnetic field When a reference current is applied to coil 4 Time from reference current The expression for the generated product is shown in equation (4).

[0028] （3） （4） In the formula, Indicates the current to be measured With the first magnetic field Conversion coefficients between them; Indicates reference current With the second magnetic field The conversion coefficient between them. When the winding structure on TMR chip 2 is fixed. It is also a constant; the conversion factor can be adjusted by changing the number of turns N of coil 4. Size.

[0029] Preferably, please refer to Figure 2The winding direction of the N-turn coil 4 is perpendicular to the magnetic field sensing direction of the TMR chip 2, and the magnetic field sensing direction of the TMR chip 2 is perpendicular to the first magnetic field in the air gap. The directions are the same. Therefore, when a reference current is passed through coil 4... At that time, the second magnetic field it generates Direction and the current to be measured The first magnetic field generated The direction is parallel, that is, the second magnetic field. The direction of the magnetic field applied to the TMR chip 2 is parallel to the magnetic field sensitive direction of the TMR chip 2. At this time, the magnetic field applied to the TMR chip 2 is [value missing], and the measured current is [value missing]. The first magnetic field generated and reference current The generated second magnetic field sum.

[0030] It should be noted that, based on the operating characteristics of TMR chip 2, the output voltage expression in equation (5) can be obtained.

[0031] （5） In the formula, This indicates the sensitivity of TMR chip 2, which is temperature-dependent; that is, the sensitivity of TMR chip 2 changes as the temperature changes. This indicates the power supply voltage of TMR chip 2, which is used to regulate the voltage of TMR chip 2 to ensure its stability.

[0032] Based on the above, substitute equations (1) to (4) into equation (5), separate the output voltage expression of equation (5) to obtain the expression of equation (6).

[0033] （6） Differential amplifier circuit 5 is used to process the first voltage signal output by TMR chip 2. Differential amplification is performed to obtain the second voltage signal. .

[0034] Signal analysis and processing module 6 processes the second voltage signal output by differential amplifier circuit 5. DFT analysis was performed to obtain the second voltage signal. Corresponding main DC voltage component Reference voltage component and multiple AC voltage components Then the main DC voltage component and reference voltage component Perform division to obtain and output the result that reflects the current being measured. Voltage data of current value .

[0035] It should be noted that DFT refers to Discrete Fourier Transform.

[0036] Preferably, the signal analysis and processing module 6 specifically includes: an analog-to-digital converter 61 and a microcontroller unit (MCU).

[0037] The analog-to-digital converter 61 is connected to the differential amplifier circuit 5 and is used to convert the second voltage signal output by the differential amplifier circuit 5 into a digital signal. Perform A / D analog-to-digital conversion to obtain the second voltage signal. The corresponding digital signal; The microcontroller unit (MCU) is connected to the analog-to-digital converter (ADC) 61, and is used to process the second voltage signal output by the differential amplifier circuit 5 (see equation (7)). DFT analysis was performed to obtain the second voltage signal. Corresponding main DC voltage component Reference voltage component and multiple AC voltage components .

[0038] （7） In the formula, Indicates the differential amplifier gain; This represents the main DC voltage component, and its relationship with the main DC component. Proportional; Indicates frequency as The AC voltage component at power frequency (i.e., the power frequency harmonic current component) Proportional; Indicates frequency as The AC voltage component at the second power frequency (i.e., the second power frequency harmonic current component) Proportional; Indicates frequency as The AC voltage component at the 3rd power frequency (i.e., the third power frequency harmonic current component) and its relationship with the 3rd power frequency harmonic current component. Proportional; This represents the reference voltage component, which is related to the reference current. Proportional. Among them, the second voltage signal Corresponding main DC voltage component , frequency is AC voltage component at time , frequency is AC voltage component at time and reference voltage component Please refer to equations (8), (9), (10), and (11) for their respective expressions.

[0039] （8） （9） （10） （11） The microcontroller unit (MCU) is used to control the second voltage signal output by the differential amplifier circuit 5. The corresponding main DC voltage components were obtained by performing DFT analysis. Reference voltage component and multiple AC voltage components Next, please refer to equation (12) to convert the main DC voltage component. and reference voltage component Perform division to obtain and output the result that reflects the current being measured. Voltage data of current value .

[0040] （12） As can be seen from equation (12), due to the conversion coefficient and All of these are structure-related constants, while The frequency controlled by the microcontroller unit (MCU) is The reference current is a known quantity, so the final voltage data output by the microcontroller unit (MCU) is... It is independent of the sensitivity of the TMR chip, and only related to the current being measured. The main DC component This unknown quantity is directly proportional.

[0041] Please refer to Figure 3 This is a flowchart illustrating a current detection method based on a TMR chip according to an embodiment of the present invention. The method includes steps S1 to S2, and the specific steps are as follows: Step S1: When the current to be measured passes through the center of the toroidal iron core with an air gap, a first voltage signal is generated based on the first magnetic field and the second magnetic field generated by the current to be measured.

[0042] The direction of the first magnetic field is the same as that of the second magnetic field. The second magnetic field is generated by the reference current when a reference current is applied to the coil wound on the TMR chip. The reference current is generated by the reference current generation circuit, and the frequency of the reference current is different from the frequency of the current to be measured.

[0043] Preferably, the winding direction of the coil is perpendicular to the magnetic field sensitive direction of the TMR chip, and the magnetic field sensitive direction of the TMR chip is the same as the direction of the first magnetic field.

[0044] Preferably, the generation of the reference current in step S1 specifically includes steps S01 to S02, each step as follows: Step S01: Perform D / A digital-to-analog conversion on the reference voltage signal output by the microcontroller unit to obtain the analog signal corresponding to the reference voltage signal.

[0045] The frequency of the reference voltage signal is different from the frequency of the current to be measured.

[0046] Step S02: The analog signal is converted into a corresponding reference current using a voltage-controlled current source.

[0047] Step S2: Differential amplification is performed on the first voltage signal output by the TMR chip placed in the air gap to obtain the second voltage signal. DFT analysis is then performed on the second voltage signal to obtain the main DC voltage component, reference voltage component, and multiple AC voltage components corresponding to the second voltage signal. Then, the main DC voltage component and the reference voltage component are divided to output voltage data that can reflect the magnitude of the current value to be measured.

[0048] As a preferred embodiment, step S2 includes steps S21 to S23, each of which is detailed below: Step S21: Differential amplification is performed on the first voltage signal output by the TMR chip to obtain the second voltage signal.

[0049] Step S22: Perform A / D analog-to-digital conversion on the second voltage signal to obtain the digital signal corresponding to the second voltage signal.

[0050] Step S23: Perform DFT analysis on the digital signal to obtain the main DC voltage component, reference voltage component and multiple AC voltage components corresponding to the second voltage signal. Then, perform a division operation on the main DC voltage component and the reference voltage component to obtain and output voltage data that can reflect the magnitude of the current value of the current to be measured.

[0051] Those skilled in the art will clearly 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 current sensor embodiments, and will not be repeated here.

[0052] Compared with the prior art, the embodiments of the present invention have the following beneficial effects: This invention provides a current sensor and current detection method based on a TMR chip. When the current to be measured passes through the center of a toroidal iron core with an air gap, a first magnetic field is generated by the current to be measured, so that the TMR chip placed in the air gap is in the first magnetic field. At the same time, a reference current with a different frequency than the current to be measured is generated by a reference current generation circuit, and the reference current is passed into a coil wound on the TMR chip. The coil generates a second magnetic field corresponding to the reference current, so that the TMR chip is in the second magnetic field. This realizes that the first magnetic field corresponding to the current to be measured and the second magnetic field corresponding to the reference current are applied to the TMR chip at the same time, so that the TMR chip outputs a first voltage signal associated with the first magnetic field and the second magnetic field. Then, the first voltage signal is differentially amplified so that the amplified second voltage signal can be subjected to DFT analysis, thereby separating the second voltage signal into a corresponding main DC voltage component, a reference voltage component, and multiple AC voltage components. Since the main DC voltage component and the reference voltage component, apart from the differential amplification gain and the sensitivity of the TMR chip, are only related to the conversion coefficient between the current and the magnetic field, the main DC component in the measured current, and the reference current, by performing a division operation on the main DC voltage component and the reference voltage component, we can obtain a calculation result that is only related to the conversion coefficient between the current and the magnetic field, the main DC component in the measured current, and the reference current, and is independent of the sensitivity of the TMR chip. This achieves compensation for the temperature dependence of the current sensor on the sensitivity of the TMR chip, enabling the detection of the measured current without knowing the temperature characteristics of the TMR chip's sensitivity, thereby eliminating the influence of the TMR chip and temperature on the accuracy and efficiency of current detection.

[0053] 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 sensor based on a TMR chip, characterized in that, include: The ring-shaped iron core with an air gap, the TMR chip placed in the air gap, the reference current generation circuit, the coil wound on the TMR chip, the differential amplifier circuit, and the signal analysis and processing module; The TMR chip is positioned in a first magnetic field and a second magnetic field with the same direction, and is used to generate a first voltage signal based on the first magnetic field and the second magnetic field; the first magnetic field is generated by the current to be measured passing through the center of the toroidal iron core, and the second magnetic field is generated by the reference current when a reference current is applied to the coil; The reference current generation circuit is used to generate the reference current; the frequency of the reference current is different from the frequency of the current to be measured. The differential amplifier circuit is used to differentially amplify the first voltage signal output by the TMR chip to obtain a second voltage signal. The signal analysis and processing module is used to perform DFT analysis on the second voltage signal output by the differential amplifier circuit to obtain the main DC voltage component, reference voltage component and multiple AC voltage components corresponding to the second voltage signal. Then, the main DC voltage component and the reference voltage component are divided to obtain and output voltage data that can reflect the magnitude of the current value of the current to be measured. The reference current generation circuit specifically includes: a digital-to-analog converter and a voltage-controlled current source; The digital-to-analog converter is connected to the microcontroller unit in the signal analysis and processing module, and is used to perform D / A digital-to-analog conversion on the reference voltage signal output by the microcontroller unit to obtain the analog signal corresponding to the reference voltage signal; The voltage-controlled current source is connected to the digital-to-analog converter and is used to convert the analog signal into the corresponding reference current; The winding direction of the coil is perpendicular to the magnetic field sensitive direction of the TMR chip, and the magnetic field sensitive direction of the TMR chip is the same as the direction of the first magnetic field.

2. A current sensor based on a TMR chip according to claim 1, characterized in that, The signal analysis and processing module specifically includes: an analog-to-digital converter and a microcontroller unit; The analog-to-digital converter is connected to the differential amplifier circuit and is used to perform A / D conversion on the second voltage signal output by the differential amplifier circuit to obtain the digital signal corresponding to the second voltage signal. The microcontroller unit, connected to the analog-to-digital converter, is used to perform DFT analysis on the digital signal to obtain the main DC voltage component, the reference voltage component, and multiple AC voltage components corresponding to the second voltage signal. The main DC voltage component and the reference voltage component are then divided to obtain and output voltage data that reflects the magnitude of the current value of the current to be measured.

3. A current detection method based on a TMR chip, characterized in that, include: When the current to be measured passes through the center of the toroidal iron core with an air gap, a first voltage signal is generated based on the first magnetic field and the second magnetic field generated by the current to be measured. The first voltage signal output by the TMR chip placed in the air gap is differentially amplified to obtain a second voltage signal. The second voltage signal is then subjected to DFT analysis to obtain the main DC voltage component, the reference voltage component, and multiple AC voltage components corresponding to the second voltage signal. The main DC voltage component and the reference voltage component are then divided to output voltage data that can reflect the magnitude of the current value of the current to be measured. Wherein, the direction of the first magnetic field is the same as the direction of the second magnetic field, and the second magnetic field is generated by the reference current when a reference current is passed through the coil wound on the TMR chip. The reference current is generated by the reference current generation circuit, and the frequency of the reference current is different from the frequency of the current to be measured. The generation of the reference current is specifically as follows: The reference voltage signal output by the microcontroller unit is subjected to D / A digital-to-analog conversion to obtain the analog signal corresponding to the reference voltage signal; The analog signal is converted into the corresponding reference current using a voltage-controlled current source; The frequency of the reference voltage signal is different from the frequency of the current to be measured. The winding direction of the coil is perpendicular to the magnetic field sensitive direction of the TMR chip, and the magnetic field sensitive direction of the TMR chip is the same as the direction of the first magnetic field.

4. The current detection method based on a TMR chip according to claim 3, characterized in that, The step of performing DFT analysis on the second voltage signal to output voltage data that reflects the magnitude of the current value to be measured specifically involves: The second voltage signal is converted from analog to digital by an A / D converter to obtain the digital signal corresponding to the second voltage signal; The digital signal is subjected to DFT analysis to obtain the main DC voltage component, the reference voltage component, and multiple AC voltage components corresponding to the second voltage signal. The main DC voltage component and the reference voltage component are divided to obtain and output voltage data that can reflect the magnitude of the current value of the current to be measured.

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