Method for calibrating residual magnetism of closed-loop current sensor, calibration system and closed-loop current sensor

Abstract

This application provides a method, system, and closed-loop current sensor residual magnetism calibration method, comprising: providing a closed-loop current sensor; establishing an initial offset value model to fit the B-H curve of the magnetic core of the closed-loop current sensor based on the B-H curve of the magnetic core; turning on the closed-loop current sensor and performing current measurement after initialization, recording the current measurement value, and obtaining the offset value of the corresponding current as the initial offset value during the operation of the closed-loop current sensor based on the initial offset value model; and dynamically calibrating the offset value of the closed-loop current sensor, wherein the dynamic calibration includes: recording the measured current value of the closed-loop current sensor as a new offset value when the measured current crosses zero from positive to negative or from negative to positive; or recording the measured current value of the closed-loop current sensor as a new offset value when the measured current is less than a first set value.

Description

Technical Field

[0001] This application relates to the field of current sensor technology, and in particular to a method, system and closed-loop current sensor for calibrating residual magnetism. Background Technology

[0002] The closed-loop Hall current sensor includes a magnetic core, Hall element, amplifier circuit and secondary compensation winding. Based on the zero flux principle, the secondary compensation winding generates a magnetic field in the magnetic core that is equal in magnitude and opposite in direction to the magnetic field generated by the primary current at the air gap, thereby canceling the primary magnetic field and forming a negative feedback closed-loop control circuit to achieve high-precision measurement and stable and accurate acquisition of current data.

[0003] To obtain better measurement results, the sensor uses the segment with better linearity in the magnetization curve as its operating range. This means that magnetic saturation occurs when the magnetic flux density exceeds a certain range beyond the linear region. Firstly, when the sensor is not powered, the secondary compensation winding does not generate current. In this case, the closed-loop Hall current sensor functions like an open-loop Hall current sensor, and magnetic saturation occurs as long as the primary current is large enough. Secondly, since the current generated by the compensation winding is limited, when the magnetic field generated by the primary current exceeds the maximum magnetic field generated by the secondary compensation winding, the magnetic balance is broken, and a magnetic field flows through the core. As the primary current continues to increase, the magnetic field in the core also increases. When the primary current is large enough, the closed-loop Hall current sensor enters a state of magnetic saturation. Core saturation leads to residual magnetism, disrupting the zero flux balance, causing zero-point drift and a decrease in linearity, resulting in measurement deviations. Summary of the Invention

[0004] This application provides a method, system, and closed-loop current sensor for remanent magnetization calibration, in order to solve the problem in the prior art where remanent magnetization due to core saturation disrupts the zero flux balance, causing zero-point drift and a decrease in linearity, resulting in deviations in measured values.

[0005] This application provides a method for calibrating the residual magnetism of a closed-loop current sensor, including:

[0006] A closed-loop current sensor is provided. Based on the BH curve of the magnetic core of the closed-loop current sensor, an initial offset value model is established to fit the BH curve of the magnetic core.

[0007] Turn on the closed-loop current sensor and perform current measurement after initialization. Record the current measurement value and obtain the corresponding current offset value according to the initial offset value model as the initial offset value during the operation of the closed-loop current sensor.

[0008] The offset value of the closed-loop current sensor is dynamically calibrated, and the dynamic calibration includes:

[0009] When the measured current crosses zero from positive to negative or from negative to positive, the measured current value of the closed-loop current sensor at this time is recorded as the new offset value; or,

[0010] When the measured current is less than the first set value, the measured current value of the closed-loop current sensor at this time is recorded as the new offset value; wherein, the first set value is set according to the sensor model.

[0011] In some embodiments, when the measured current crosses zero from positive to negative or from negative to positive, the output value of the closed-loop current sensor at this time is recorded as a new offset value, including:

[0012] The changes in the primary current are monitored in real time. When the current crosses zero from positive to negative or from negative to positive, the measured current value that remains unchanged for a first set time is recorded as the new offset value. The first set time is set according to the sensor model.

[0013] In some embodiments, the closed-loop current sensor residual magnetism calibration method further includes the following steps:

[0014] After the current crosses zero from positive to negative or from negative to positive, the current values ​​at multiple sampling points are continuously monitored:

[0015] If the current values ​​at all sampling points show that the current direction has reversed, and the current change near the zero point is smooth with no sudden changes or noise interference, then it is determined that the current value has crossed the zero point and the new offset value is locked.

[0016] If a sudden change in current value or significant noise interference is detected during monitoring, the offset value of the closed-loop current sensor is dynamically recalibrated, and monitoring continues.

[0017] In some embodiments, when the measured current is less than a first set value, the measured current value of the closed-loop current sensor at this time is recorded as a new offset value, including:

[0018] When the measured current is less than the first set value and remains so for a second set time, the measured current value of the closed-loop current sensor is continuously collected, and the average value is taken as the new offset value; wherein, the second set time is set according to the sensor model.

[0019] In some embodiments, the closed-loop current sensor residual magnetism calibration method further includes:

[0020] To verify the new offset value, when the measured current crosses zero from positive to negative or from negative to positive, record the measured current value of the closed-loop current sensor at this time as the calibration offset value, and compare the calibration offset value with the new offset value:

[0021] If the error is less than or equal to the second set value, lock the new offset value;

[0022] If the error exceeds the second set value, the offset value of the closed-loop current sensor is dynamically recalibrated.

[0023] In some embodiments, an initial offset value model is established to fit the BH curve of the magnetic core based on the BH curve of the closed-loop current sensor, including:

[0024] When the measured current is greater than or equal to the rated current of the closed-loop current sensor, the initial offset value is set to X1, and the value of X1 is set according to the sensor model.

[0025] When the measured current is greater than or equal to 10% of the rated current of the closed-loop current sensor and less than the rated current of the closed-loop current sensor, the initial offset value is set to X2, and X2 = a0 + a1x, where the values ​​of a0 and a1 are matched according to the specific sensor model, and x is the measured current value.

[0026] When the measured current is greater than or equal to 0.1% of the rated current of the closed-loop current sensor and less than 10% of the rated current of the closed-loop current sensor, the initial offset value is set to X3. The value of X3 is set according to the sensor model, and X3 < X1.

[0027] When the measured current is less than 0.1% of the rated current of the closed-loop current sensor, the initial offset value is set to X4, and X4 = x.

[0028] A second aspect of this application provides a closed-loop current sensor residual magnetism calibration system for implementing the closed-loop current sensor residual magnetism calibration method described in any of the above embodiments, including:

[0029] A data acquisition module, wherein the input end of the data acquisition module is adapted to be connected to the measurement output end of the closed-loop current sensor, and the data acquisition module is used to acquire the measured current value of the closed-loop current sensor in real time;

[0030] An initial offset value module, the input of which is connected to the output of the data acquisition module, is used to output a corresponding initial offset value based on the measured current value of the closed-loop current sensor;

[0031] The dynamic calibration module has its input terminal connected to the output terminal of the data acquisition module. When the measured current crosses zero from positive to negative or from negative to positive, the dynamic calibration module records the measured current value of the closed-loop current sensor at this time as a new offset value; or, when the measured current is less than a first set value, the dynamic calibration module records the output value of the closed-loop current sensor at this time as a new offset value.

[0032] The output module has its input terminals connected to the output terminals of the initial offset value module and the dynamic calibration module, respectively. The output terminal of the output module is adapted to be connected to the final output terminal of the closed-loop current sensor. The output module is used to output the initial offset value and the new offset value to compensate for the measured current value of the closed-loop current sensor.

[0033] In some embodiments, the closed-loop current sensor residual magnetism calibration system further includes:

[0034] The control module has its signal input terminals connected to the output terminals of the data acquisition module and the dynamic calibration module, respectively. The control terminal of the control module is connected to the input terminal of the dynamic calibration module. When the measured current crosses zero from positive to negative or from negative to positive, the dynamic calibration module records the output value of the closed-loop current sensor at this time as a calibration offset value. The module compares the calibration offset value with a new offset value: if the error is less than or equal to a second set value, the new offset value is locked; if the error is greater than the second set value, the offset value of the closed-loop current sensor is recalibrated dynamically.

[0035] A third aspect of this application provides a closed-loop current sensor, including the residual magnetism calibration system for the closed-loop current sensor described in any of the preceding embodiments.

[0036] The closed-loop current sensor residual magnetism calibration method of this application establishes an initial offset value model to perform initial compensation on the closed-loop current sensor, and then performs dynamic calibration of the offset value to complete the automatic calibration and compensation of the residual magnetism of the closed-loop current sensor. This effectively solves the problem of zero-point measurement error caused by residual magnetism of the magnetic core and improves the accuracy of current measurement. During dynamic calibration, the new offset value is refreshed only in the small current stage to avoid miscalibration. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of a closed-loop current sensor residual magnetism calibration method according to an embodiment of this application.

[0038] Figure 2 This is a schematic diagram of a closed-loop current sensor residual magnetism calibration system according to an embodiment of this application. Detailed Implementation

[0039] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0040] refer to Figure 1 , Figure 1This is a schematic diagram of a closed-loop current sensor residual magnetism calibration method according to an embodiment of this application. The closed-loop current sensor residual magnetism calibration method includes:

[0041] S1. Provide a closed-loop current sensor. Based on the BH curve of the magnetic core of the closed-loop current sensor, establish an initial offset value model to fit the BH curve of the magnetic core.

[0042] It should be noted that the closed-loop current sensor includes a magnetic core, a Hall element, an amplifier circuit, and a secondary compensation winding. When the sensor is not working, the magnetic field generated by the primary current acts on the magnetic core, which may generate residual magnetism, thus affecting the sensor's measurement value. By obtaining the BH curve of the magnetic core through experiments, and establishing an initial offset model (e.g., a polynomial) for fitting the BH curve of the magnetic core based on the BH curve, the sensor can be initially compensated to ensure its accuracy.

[0043] S2. Turn on the closed-loop current sensor and perform current measurement after initialization. Record the current measurement value and obtain the corresponding current offset value as the initial offset value in the operation of the closed-loop current sensor according to the initial offset value model.

[0044] S3. Perform dynamic calibration on the offset value of the closed-loop current sensor. Dynamic calibration includes: when the measured current crosses zero from positive to negative or from negative to positive, record the measured current value of the closed-loop current sensor at this time as the new offset value; or, when the measured current is less than the first set value, record the measured current value of the closed-loop current sensor at this time as the new offset value; wherein, the first set value is set according to the sensor model.

[0045] It should be noted that when the current crosses zero (from positive to negative or from negative to positive), because the system is a DC system, the current cannot switch instantaneously during the switching process. Therefore, the measured current that remains basically unchanged for a certain period of time during the switching process can be considered as the offset value and used as the new offset value to compensate the sensor. The first set value is set according to the sensor model and is usually less than 0.1% of the sensor's rated current. When the sensor is below the first set value for a long time, it can be considered as the offset value and used as the new offset value to compensate the sensor.

[0046] The closed-loop current sensor residual magnetism calibration method of this application establishes an initial offset value model to perform initial compensation on the closed-loop current sensor, and then performs dynamic calibration of the offset value to complete the automatic calibration and compensation of the residual magnetism of the closed-loop current sensor. This effectively solves the problem of zero-point measurement error caused by residual magnetism of the magnetic core and improves the accuracy of current measurement. During dynamic calibration, the new offset value is refreshed only in the small current stage to avoid miscalibration.

[0047] In some embodiments, when the measured current crosses zero from positive to negative or from negative to positive, the output value of the closed-loop current sensor at this time is recorded as a new offset value, including:

[0048] The system monitors changes in the primary current in real time. When the current crosses zero from positive to negative or from negative to positive, the measured current value that remains unchanged for a first set time period is recorded as the new offset value. The first set time period is set according to the sensor model.

[0049] It should be noted that when the current crosses zero (from positive to negative or from negative to positive), the current cannot switch instantaneously during the switching process because the system is a DC system. In order to avoid instantaneous noise interference, the measured current that remains basically unchanged during the first set time during the switching process needs to be selected as the new offset value to calibrate and compensate the sensor and improve the sensor's accuracy. The first set time is set according to the sensor model and is usually not less than 300 milliseconds.

[0050] Furthermore, in some embodiments, the closed-loop current sensor residual magnetism calibration method further includes the following steps:

[0051] After the current crosses zero from positive to negative or from negative to positive, the current values ​​at multiple sampling points are continuously monitored:

[0052] If the current values ​​at all sampling points show that the current direction has reversed, and the current change near the zero point is smooth with no sudden changes or noise interference, then it is determined that the current value has crossed the zero point and the new offset value is locked.

[0053] If a sudden change in current value or significant noise interference is detected during monitoring, the offset value of the closed-loop current sensor is dynamically recalibrated, and monitoring continues.

[0054] It should be noted that, to avoid misjudgment, after the current crosses zero from positive to negative or from negative to positive, multiple sampling points need to be collected near the zero-crossing point, and the current values ​​at these multiple sampling points need to be monitored. The number of sampling points can be set according to the actual application requirements and the performance of the sensor, but is usually no less than 10. After sampling, the multiple sampling points are analyzed. When the current values ​​at all sampling points reverse, and the current change near the zero-crossing point is smooth without abrupt changes or noise interference, it indicates that the measured current value of the sensor can be used as the new offset value. When some current values ​​do not reverse, or the sampled current values ​​have abrupt changes or significant noise interference, it indicates that the measured current value of the sensor may have a large error when used as the new offset value, and the offset value of the closed-loop current sensor needs to be dynamically calibrated again.

[0055] In some embodiments, when the measured current is less than a first set value, the measured current value of the closed-loop current sensor at this time is recorded as a new offset value, including:

[0056] When the measured current is less than the first set value and remains at the second set value for a period of time, the measured current value of the closed-loop current sensor is continuously collected, and the average value is taken as the new offset value; wherein, the second set value is set according to the sensor model, and is usually not less than 300 milliseconds.

[0057] It should be noted that when the sensor measurement value is less than the first set value for a long time, the primary current can be considered to be 0, and the measurement value at this time is the sensor offset value. In order to avoid the instantaneous noise interference affecting the accuracy of the new offset value, it is necessary to continuously collect the measured current value of the closed-loop current sensor and take the average value as the new offset value for slow updating.

[0058] In some embodiments, the closed-loop current sensor residual magnetism calibration method further includes:

[0059] To verify the new offset value, when the measured current crosses zero from positive to negative or from negative to positive, record the measured current value of the closed-loop current sensor at this time as the calibration offset value, and compare the calibration offset value with the new offset value:

[0060] If the error is less than or equal to the second set value, lock the new offset value;

[0061] If the error exceeds the second set value, the offset value of the closed-loop current sensor is dynamically recalibrated.

[0062] It should be noted that when the current crosses zero (from positive to negative or from negative to positive), the current cannot switch instantaneously during the switching process because the system is a DC system. At this time, the sensor's measured value can be considered as the sensor's offset value. Using this characteristic, the new offset value can be verified. When the error between the calibrated offset value and the new offset value is less than or equal to the second set value, the new offset value can be considered accurate. When the error is greater than the second set value, the new offset value can be considered to be disturbed and the difference is large, and the offset value of the closed-loop current sensor needs to be dynamically calibrated again. The second set value is set according to the sensor model and the actual use scenario, and the second set value is usually no greater than 5%.

[0063] In some specific embodiments, an initial offset value model is established to fit the BH curve of the magnetic core based on the BH curve of the closed-loop current sensor, including:

[0064] When measuring a current greater than or equal to the rated current of the closed-loop current sensor, set the initial offset value to X1. The value of X1 is set according to the sensor model; for example, for a sensor with a rated current of 500A, the value of X1 is 0.25A.

[0065] When the measured current is greater than or equal to 10% of the rated current of the closed-loop current sensor and less than the rated current of the closed-loop current sensor, the initial offset value is set to X2, and X2 = a0 + a1x, where the values ​​of a0 and a1 are matched according to the specific sensor model, and x is the measured current value; taking a sensor with a rated current of 500A as an example, a0 = 0.0833, a1 = 0.00033.

[0066] When the measured current is greater than or equal to 0.1% of the rated current of the closed-loop current sensor and less than 10% of the rated current of the closed-loop current sensor, the initial offset value is set to X3. The value of X3 is set according to the sensor model, and X3 < X1; taking a sensor with a rated current of 500A as an example, X3 = 0.01A.

[0067] When the measured current is less than 0.1% of the rated current of the closed-loop current sensor, the initial offset value is set to X4, and X4 = x, where x is also the measured current value.

[0068] refer to Figure 2 The second aspect of this application provides a closed-loop current sensor residual magnetism calibration system for implementing the closed-loop current sensor residual magnetism calibration method of any of the above embodiments, comprising:

[0069] The data acquisition module has an input terminal that is adapted to be connected to the measurement output terminal of the closed-loop current sensor. The data acquisition module is used to acquire the measured current value of the closed-loop current sensor in real time.

[0070] The initial offset value module has its input end connected to the output end of the data acquisition module. The initial offset value module is used to output the corresponding initial offset value based on the measured current value of the closed-loop current sensor.

[0071] The dynamic calibration module has its input connected to the output of the data acquisition module. When the measured current crosses zero from positive to negative or from negative to positive, the dynamic calibration module records the measured current value of the closed-loop current sensor as a new offset value. Alternatively, when the measured current is less than a first set value, the dynamic calibration module records the output value of the closed-loop current sensor as a new offset value.

[0072] The output module has its input terminals connected to the output terminals of the initial offset value module and the dynamic calibration module, respectively. The output terminal of the output module is adapted to be connected to the final output terminal of the closed-loop current sensor. The output module is used to output the initial offset value and the new offset value to compensate for the measured current value of the closed-loop current sensor.

[0073] When using the closed-loop current sensor residual magnetism calibration system of this application, the sensor is started, the data acquisition module acquires the measured current value of the closed-loop current sensor, and feeds the measured current value back to the initial offset value module. The initial offset value module outputs the corresponding initial offset value to the output module based on the measured current value of the closed-loop current sensor. The output module outputs the initial offset value to perform initial compensation on the measured current value of the closed-loop current sensor. Subsequently, the data acquisition module acquires the measured current value of the closed-loop current sensor in real time and feeds it back to the dynamic calibration module. The dynamic calibration module updates the offset value during the low current stage and outputs a new offset value to the output module. The output module outputs a new offset value to compensate for the measured current value of the closed-loop current sensor.

[0074] In some embodiments, the closed-loop current sensor residual magnetism calibration system further includes:

[0075] The control module's signal input terminal is connected to the output terminals of both the data acquisition module and the dynamic calibration module. The control terminal of the control module is connected to the input terminal of the dynamic calibration module. When the measured current crosses zero from positive to negative or from negative to positive, the dynamic calibration module records the output value of the closed-loop current sensor at this time as the calibration offset value. The calibration offset value and the new offset value are compared: if the error is less than or equal to the second set value, the new offset value is locked; if the error is greater than the second set value, the offset value of the closed-loop current sensor is recalibrated dynamically.

[0076] A third aspect of this application provides a closed-loop current sensor, including the residual magnetism calibration system for the closed-loop current sensor of any of the above embodiments.

[0077] The closed-loop current sensor of this application embodiment uses a closed-loop current sensor residual magnetism calibration system according to any of the above embodiments to perform initial compensation on the closed-loop current sensor, followed by dynamic calibration of the offset value, to complete the automatic calibration and compensation of the residual magnetism of the closed-loop current sensor, effectively solving the problem of zero-point measurement error caused by magnetic core residual magnetism and improving the current measurement accuracy; during dynamic calibration, the new offset value is refreshed only in the small current stage, avoiding miscalibration.

[0078] In the description of this application, it should be understood that terms such as “first” and “second” are used only to distinguish similar objects and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated.

[0079] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0080] It should be understood that the terms "upper," "lower," "left," "right," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. In the description of the present invention, unless otherwise stated, "a plurality of" means two or more.

[0081] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the embodiments above are only for the purpose of helping to understand this application. At the same time, those skilled in the art will find that, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A method for calibrating the residual magnetism of a closed-loop current sensor, characterized in that, include: A closed-loop current sensor is provided. Based on the BH curve of the magnetic core of the closed-loop current sensor, an initial offset value model is established to perform initial compensation on the closed-loop current sensor. This includes: when the measured current is greater than or equal to the rated current of the closed-loop current sensor, an initial offset value of X1 is set, where the value of X1 is set according to the sensor model; when the measured current is greater than or equal to 10% of the rated current of the closed-loop current sensor and less than the rated current of the closed-loop current sensor, an initial offset value of X2 is set, where X2 = a0 + a1x, and the values ​​of a0 and a1 are matched according to the specific sensor model, and x is the measured current value; when the measured current is greater than or equal to 0.1% of the rated current of the closed-loop current sensor and less than 10% of the rated current of the closed-loop current sensor, an initial offset value of X3 is set, where the value of X3 is set according to the sensor model, and X3 < X1; when the measured current is less than 0.1% of the rated current of the closed-loop current sensor, an initial offset value of X4 is set, where X4 = x. Turn on the closed-loop current sensor and perform current measurement after initialization. Record the current measurement value and obtain the corresponding current offset value according to the initial offset value model as the initial offset value during the operation of the closed-loop current sensor. The offset value of the closed-loop current sensor is dynamically calibrated, and the dynamic calibration includes: When the measured current crosses zero from positive to negative or from negative to positive, the measured current value of the closed-loop current sensor at this time is recorded as the new offset value; or, When the measured current is less than the first set value, the measured current value of the closed-loop current sensor at this time is recorded as the new offset value; wherein, the first set value is set according to the sensor model.

2. The closed-loop current sensor residual magnetism calibration method according to claim 1, characterized in that, When the measured current crosses zero from positive to negative or from negative to positive, the output value of the closed-loop current sensor at this moment is recorded as the new offset value, including: The changes in the primary current are monitored in real time. When the current crosses zero from positive to negative or from negative to positive, the measured current value that remains unchanged for a first set time is recorded as the new offset value. The first set time is set according to the sensor model.

3. The closed-loop current sensor residual magnetism calibration method according to claim 2, characterized in that, It also includes the following steps: After the current crosses zero from positive to negative or from negative to positive, the current values ​​at multiple sampling points are continuously monitored: If the current values ​​at all sampling points show that the current direction has reversed, and the current change near the zero point is smooth with no sudden changes or noise interference, then it is determined that the current value has crossed the zero point and the new offset value is locked. If a sudden change in current value or significant noise interference is detected during monitoring, the offset value of the closed-loop current sensor is dynamically recalibrated, and monitoring continues.

4. The closed-loop current sensor residual magnetism calibration method according to claim 1, characterized in that, When the measured current is less than the first set value, the measured current value of the closed-loop current sensor at this time is recorded as the new offset value, including: When the measured current is less than the first set value and remains so for a second set time, the measured current value of the closed-loop current sensor is continuously collected, and the average value is taken as the new offset value; wherein, the second set time is set according to the sensor model.

5. The closed-loop current sensor residual magnetism calibration method according to claim 4, characterized in that, It also includes the following steps: When the measured current crosses zero from positive to negative or from negative to positive, record the measured current value of the closed-loop current sensor at this time as the calibration offset value, and compare the calibration offset value with the new offset value: If the error is less than or equal to the second set value, lock the new offset value; If the error exceeds the second set value, the offset value of the closed-loop current sensor is dynamically recalibrated.

6. A closed-loop current sensor residual magnetism calibration system, used to implement the closed-loop current sensor residual magnetism calibration method according to any one of claims 1-5, characterized in that, include: A data acquisition module, wherein the input end of the data acquisition module is adapted to be connected to the measurement output end of the closed-loop current sensor, and the data acquisition module is used to acquire the measured current value of the closed-loop current sensor in real time; An initial offset value module, the input of which is connected to the output of the data acquisition module, is used to output a corresponding initial offset value based on the measured current value of the closed-loop current sensor; The dynamic calibration module has its input terminal connected to the output terminal of the data acquisition module. When the measured current crosses zero from positive to negative or from negative to positive, the dynamic calibration module records the measured current value of the closed-loop current sensor at this time as a new offset value; or, when the measured current is less than a first set value, the dynamic calibration module records the output value of the closed-loop current sensor at this time as a new offset value. The output module has its input terminals connected to the output terminals of the initial offset value module and the dynamic calibration module, respectively. The output terminal of the output module is adapted to be connected to the final output terminal of the closed-loop current sensor. The output module is used to output the initial offset value and the new offset value to compensate for the measured current value of the closed-loop current sensor.

7. The closed-loop current sensor residual magnetism calibration system according to claim 6, characterized in that, Also includes: The control module has its signal input terminals connected to the output terminals of the data acquisition module and the dynamic calibration module, respectively. The control terminal of the control module is connected to the input terminal of the dynamic calibration module. When the measured current crosses zero from positive to negative or from negative to positive, the dynamic calibration module records the output value of the closed-loop current sensor at this time as a calibration offset value. The module compares the calibration offset value with a new offset value: if the error is less than or equal to a second set value, the new offset value is locked; if the error is greater than the second set value, the offset value of the closed-loop current sensor is recalibrated dynamically.

8. A closed-loop current sensor, characterized in that, Includes the closed-loop current sensor residual magnetism calibration system according to claim 6 or 7.

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