Current sensor, current measurement method, device and storage medium

Abstract

The present invention discloses a current sensor, a current measurement method, a device and a storage medium. The current sensor includes: a compensated magnetoresistive sensing unit, which is used to sense the temperature around the conductor to be measured and output a first signal that changes monotonically only with the temperature; a magnetically sensitive magnetoresistive sensing unit, which is used to sense the magnetic field around the conductor to be measured and output a second signal; and a control unit, which is used to determine the compensated input voltage of the magnetically sensitive magnetoresistive sensing unit according to the first signal, adjust the input voltage of the magnetically sensitive magnetoresistive sensing unit to the sum of the first input voltage and the compensated input voltage, and determine the load current of the conductor to be measured according to the compensated input voltage, the first signal and the second signal. The present invention uses the synergistic effect of the compensated magnetoresistive sensing unit, the magnetically sensitive magnetoresistive sensing unit and the control unit to make the output measurement result close to the true value, reduce the influence of temperature factors on the current measurement result, and improve the stability of current measurement.

Description

Technical Field

[0001] The present invention relates to the field of current measurement, and in particular to a current sensor, a current measurement method, a device and a storage medium. Background Art

[0002] The current sensor based on the tunneling magnetoresistance effect has excellent performance in terms of resolution, sensitivity, power consumption, magnetic field operating range, etc., and has broad application prospects in the field of current measurement in power systems.

[0003] In actual use, temperature changes in the operating environment of the current sensor often cause zero-point temperature drift and sensitivity drift, which seriously affects the accuracy of its current measurement.

[0004] The above contents are only used to assist in understanding the technical solution of the present invention and do not constitute an admission that the above contents are prior art. Summary of the invention

[0005] The object of the present invention is to provide a current sensor, a current measurement method, a device and a storage medium, aiming to improve the problem that the current measurement accuracy of the existing current sensor is not high under different ambient temperatures.

[0006] To achieve the above objective, a first aspect of the present invention provides a current sensor.

[0007] The current sensor comprises:

[0008] A compensating magnetic resistance sensing unit, used for sensing the temperature around the conductor to be measured and outputting a first signal; the first signal changes monotonically only with the temperature;

[0009] A magnetoresistive sensing unit, used for sensing the magnetic field around the conductor to be measured and outputting a second signal; when the load current of the conductor to be measured is zero, the difference between the second signal and the first signal is a constant;

[0010] A control unit is used to determine the compensation input voltage according to the first signal, adjust the input voltage of the magnetic-sensitive magnetoresistive sensor unit to the sum of the first input voltage and the compensation input voltage so that the sensitivity of the magnetic-sensitive magnetoresistive sensor unit does not change with temperature, and determine the load current of the conductor to be measured according to the compensation input voltage, the second signal and the first signal.

[0011] According to some embodiments of the present invention, the magnetic sensitive magnetoresistive sensing unit and the compensating magnetoresistive sensing unit are both Wheatstone full-bridge structures;

[0012] The magnetic sensitivity direction of the magnetic sensitive magnetoresistive sensing unit is parallel to the direction of the magnetic field around it;

[0013] The magnetic sensitivity direction of the compensation magnetoresistive sensing unit is perpendicular to the direction of the magnetic field around it, or the compensation magnetoresistive sensing unit is in a magnetic saturation state.

[0014] According to some embodiments of the present invention, the load current I of the conductor to be tested conforms to the formula: Where Z(T 1 ) is the first signal; U 2 (T 1 ) is the second signal; V cs (T 1 ) is the compensation input voltage; V cc is the first input voltage; V 1 is the input voltage of the compensating magnetoresistive sensing unit; S 目标 is the target sensitivity of the magnetoresistive sensing unit.

[0015] According to some embodiments of the present invention, the control unit comprises:

[0016] A storage module, used to store a first corresponding relationship between a first signal of the compensating magnetoresistive sensing unit and temperature, an input voltage of the compensating magnetoresistive sensing unit, a second corresponding relationship between the sensitivity of the magnetoresistive sensing unit and temperature, the first input voltage, and a target sensitivity of the magnetoresistive sensing unit;

[0017] An acquisition module, used for acquiring a current first signal output by the compensating magnetoresistive sensing unit and a current second signal output by the magnetoresistive magnetoresistive sensing unit;

[0018] A determination module, configured to determine a current ambient temperature according to the current first signal and the first pre-stored corresponding relationship;

[0019] The adjustment module is used to send instructions to adjust the current input voltage of the magnetic sensitive magnetoresistive sensor unit to the sum of the first input voltage and the current compensation input voltage.

[0020] According to some embodiments of the present invention, the determination module is further used to determine the current sensitivity of the magnetic-sensitive magnetoresistive sensor unit according to the current ambient temperature and the second pre-stored corresponding relationship.

[0021] According to some embodiments of the present invention, the determination module is further configured to determine a current compensation input voltage based on the current sensitivity, the pre-stored target sensitivity and the first input voltage; wherein the current compensation input voltage V cs (T 1 ) conforms to the formula: S 目标 is the target sensitivity; S 当前 is the current sensitivity; V ccis the first input voltage.

[0022] According to some embodiments of the present invention, the determining module is further configured to determine the following formula: Determine the load current of the conductor to be tested, where Z(T 1 ) is the first signal; U 2 (T 1 ) is the second signal; V 1 is the input voltage of the compensated magnetoresistive sensing unit.

[0023] To achieve the above object, a second aspect of the present invention provides a current measurement method, which is applied to the current sensor as described above; the method comprises:

[0024] Acquiring a current first signal output by the compensating magnetic resistance sensing unit;

[0025] Determine the current ambient temperature according to the current first signal and a pre-stored first correspondence between the first signal of the compensated magnetoresistive sensing unit and the temperature;

[0026] Determining the current sensitivity of the magnetic-sensitive magnetoresistive sensor unit according to the current ambient temperature and a pre-stored second corresponding relationship between the sensitivity of the magnetic-sensitive magnetoresistive sensor unit and the temperature;

[0027] The current compensation input voltage is determined according to the current sensitivity, the pre-stored target sensitivity of the magnetic sensitive magnetoresistive sensing unit and the first input voltage of the magnetic sensitive magnetoresistive sensing unit; wherein the current compensation input voltage V cs (T 1 ) conforms to the formula: S 目标 is the target sensitivity; S 当前 is the current sensitivity; V cc is the first input voltage;

[0028] Adjusting the current input voltage of the magnetic-sensitive magnetoresistive sensing unit to be the sum of the first input voltage and the current compensation input voltage, and acquiring the current second signal output by the magnetic-sensitive magnetoresistive sensing unit;

[0029] The load current of the conductor to be measured is determined according to the compensation input voltage, the current second signal and the current first signal.

[0030] According to some embodiments of the present invention, the step of adjusting the current input voltage of the magnetic-sensitive magnetoresistive sensing unit to be the sum of the first input voltage and the current compensation input voltage includes:

[0031] Acquiring a first signal change rate of the compensated magnetic resistance sensing unit;

[0032] Determining whether the first signal change rate is higher than a first threshold;

[0033] When the first signal change rate is higher than the first threshold, the current input voltage of the magnetic-sensitive magnetoresistive sensing unit is adjusted to be the sum of the first input voltage and the current compensation input voltage.

[0034] According to some embodiments of the present invention, the method further includes: acquiring a first corresponding relationship between a first signal of the compensated magnetoresistive sensing unit and temperature.

[0035] According to some embodiments of the present invention, obtaining a first corresponding relationship between the first signal of the compensated magnetoresistive sensing unit and the temperature includes:

[0036] Testing the output signal of the compensated magnetoresistive sensor unit under multiple ambient temperatures to obtain first test data;

[0037] Constructing a first fitting relationship curve between the output signal of the compensation magnetoresistive sensing unit and the temperature according to the first test data;

[0038] Determining a first corresponding relationship between a first signal of the compensated magnetic resistance sensing unit and temperature according to the fitting relationship curve;

[0039] According to some embodiments of the present invention, the first fitting relationship curve conforms to a first multi-order function.

[0040] According to some embodiments of the present invention, the method further includes: obtaining a second corresponding relationship between the sensitivity of the magnetic-sensitive magnetoresistive sensing unit and the temperature.

[0041] According to some embodiments of the present invention, obtaining a second corresponding relationship between the sensitivity of the magnetic sensitive magnetoresistive sensing unit and the temperature includes:

[0042] Testing the change of the magnetic field of the magnetic sensitive magnetoresistive sensor unit under multiple ambient temperatures to obtain second test data; the input voltage of the magnetic sensitive magnetoresistive sensor unit is the first input voltage;

[0043] Constructing a second fitting relationship curve between the sensitivity and temperature of the magnetic sensitive magnetoresistive sensing unit according to the second test data;

[0044] According to the second fitting relationship curve, a second corresponding relationship between the sensitivity of the magnetic-sensitive magnetoresistive sensor unit and the temperature is determined.

[0045] According to some embodiments of the present invention, the second fitting relationship curve conforms to a second multi-order function.

[0046] According to some embodiments of the present invention, determining the load current of the conductor to be measured based on the compensation input voltage, the current second signal and the current first signal includes: based on the formula: Determine the load current of the conductor to be tested, where Z(T 1 ) is the first signal; U 2 (T 1 ) is the second signal; V 1 is the input voltage of the compensated magnetoresistive sensing unit.

[0047] To achieve the above objectives, the third aspect of the present invention provides a current measuring device, which includes: a memory, a processor, and a current measurement program stored in the memory and running on the processor, wherein the current measurement program is configured to implement the steps of the current measurement method as described above.

[0048] To achieve the above objective, a fourth aspect of the present invention provides a storage medium, on which a current measurement program is stored, and when the current measurement program is executed by a processor, the steps of the current measurement method described above are implemented.

[0049] Therefore, the present invention has the following beneficial effects:

[0050] The current sensor provided by the present invention includes a compensated magnetoresistive sensing unit, a magnetosensitive magnetoresistive sensing unit and a control unit. The compensated magnetoresistive sensing unit is used to sense the temperature around the conductor to be measured and output a first signal that changes monotonically only with the temperature; the magnetosensitive magnetoresistive sensing unit is used to sense the magnetic field around the conductor to be measured and output a second signal; the control unit is used to determine the compensated input voltage of the magnetosensitive magnetoresistive sensing unit according to the first signal, adjust the input voltage of the magnetosensitive magnetoresistive sensing unit to the sum of the first input voltage and the compensated input voltage, and determine the load current of the conductor to be measured according to the compensated input voltage, the first signal and the second signal. The present invention uses the synergistic effect of the compensated magnetoresistive sensing unit, the magnetosensitive magnetoresistive sensing unit and the control unit to make the output measurement result close to the true value, reduce the influence of temperature factors on the current measurement result, and improve the measurement accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 is a structural block diagram of a current sensor according to an embodiment of the present invention;

[0052] Figure 2 A zero-point temperature drift curve diagram and a sensitivity change curve diagram of a current sensor of the present invention at various ambient temperatures are shown;

[0053] Figure 3 A zero-point temperature drift curve and a sensitivity change curve of a current sensor under various ambient temperatures according to an embodiment of the present invention;

[0054] Figure 4 A graph showing the output voltage of a current sensor used for AC current measurement and the current signal of a conductor to be measured changing with time according to an embodiment of the present invention;

[0055] Figure 5 FIG. 4 is a flow chart of a current measurement method according to an embodiment of the present invention.

[0056] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0057] It should be understood that the specific embodiments described herein are only used to explain the present invention, and are not used to limit the present invention.

[0058] The current sensor based on the tunneling magnetoresistance effect has excellent performance in terms of resolution, sensitivity, power consumption, magnetic field operating range, etc., and has broad application prospects in the field of current measurement in power systems.

[0059] In actual use, current sensors often experience zero-point drift and sensitivity drift due to temperature changes, which seriously affects the accuracy of their current measurement.

[0060] Therefore, a first aspect of an embodiment of the present invention is to provide a current sensor, aiming to improve the problem that the current sensor has low current measurement accuracy under different ambient temperatures.

[0061] Reference Figure 1 , Figure 1 4 is a structural block diagram of a current sensor according to an embodiment of the present invention.

[0062] The current sensor of the embodiment of the present invention includes a compensated magnetoresistive sensing unit 10 , a magnetoresistive magnetoresistive sensing unit 20 and a control unit (a control subunit 31 , an adding subunit 33 and a processing subunit 32 ).

[0063] The compensation magnetic sensitive sensing unit 10 is used to sense the temperature around the conductor to be measured and output a first signal Z(T 1 ); the first signal changes monotonically only with temperature.

[0064] The magnetic sensitive magnetoresistive sensing unit 20 is used to sense the magnetic field H around the conductor to be tested and output a second signal U 2 (T 1 ); When the load current of the conductor to be tested is zero, the second signal U 2 (T 1 ) and the first signal Z(T 1 ) is zero or a constant.

[0065] The first aspect of the control unit is used to determine the output signal of the first signal Z(T 1) and pre-stored information to determine the compensation input voltage V of the magnetic sensitive magnetoresistive sensor unit 20 cs (T 1 ), the pre-stored information may be a first corresponding relationship Z(T) between the first signal and the temperature, a second corresponding relationship S(T) between the sensitivity of the magnetic sensitive magnetoresistive sensing unit and the temperature, an input voltage V cc , target sensitivity S of the magnetoresistive sensing unit 目标 Or other information; The second aspect of the control unit is used to adjust the input voltage of the magnetic sensitive magnetoresistive sensing unit 20 to the first input voltage V cc With the compensation input voltage V cs (T 1 ) makes the second signal of the magnetoresistive sensing unit be U 1 (T 1 )Adjust to U 2 (T 1 ); The third aspect of the control unit is used to compensate the input voltage V cs (T 1 ), the second signal U 2 (T 1 ) and the first signal Z(T 1 )Determine the load current I of the conductor to be tested.

[0066] It should be understood that the magnetic sensitive magnetoresistive sensing unit and the compensating magnetic sensitive magnetoresistive sensing unit are based on the same magnetoresistive effect, and can sensitively respond to the magnetic field in the magnetic sensitive direction, and output the magnetic field strength of the external magnetic field or the load current of the source wire generated by the magnetic field. The magnetoresistive effect can be a tunneling magnetoresistive effect, a giant magnetoresistive effect, anisotropic magnetoresistive effect or other magnetoresistive effect. Under zero magnetic field, the ratio of the input voltage to the output voltage of the magnetic sensitive magnetoresistive sensing unit is the same as the ratio of the input voltage to the output voltage of the compensating magnetic sensitive magnetoresistive sensing unit.

[0067] The compensated magnetoresistive sensing unit of the embodiment of the present invention is used for temperature guidance. The current ambient temperature can be simply obtained according to its first signal and pre-obtained information. The sensitivity information of the magnetoresistive sensing unit at the current temperature can be further obtained according to the current ambient temperature and the pre-obtained correlation information of the ambient temperature and the sensitivity, thereby obtaining the current sensitivity information of the magnetoresistive sensing unit without the temperature sensor. The compensated magnetoresistive sensing unit is also used for zero-point temperature drift guidance. Based on the fact that the ratio of the input voltage to the output voltage of the magnetoresistive sensing unit under zero magnetic field is the same as the ratio of the input voltage to the output voltage of the compensated magnetoresistive sensing unit, the output voltage of the magnetoresistive sensing unit under zero magnetic field, i.e., the zero-point temperature drift, can be simply obtained, thereby obtaining the true output signal of the magnetoresistive sensing unit without considering the zero-point temperature drift.

[0068] The process of determining the compensation input voltage in the magnetoresistive sensing unit of the embodiment of the present invention includes:

[0069] (1) Based on the basic characteristics of the magnetoresistive sensor element, on the basis of compensating that the first signal output by the magnetoresistive sensor unit changes only monotonically with temperature, the first corresponding relationship Z(T) between the first signal and temperature obtained in advance and the current first signal Z(T) can be calculated. 1 ) information to obtain the current ambient temperature T 1 information.

[0070] (2) Since the sensitivity of the magnetic sensitive magnetoresistive sensor unit changes monotonically with temperature at the same input voltage, based on the second corresponding relationship S(T) between sensitivity and temperature obtained in advance, the current ambient temperature T 1 After the information is obtained, the current sensitivity S(T 1 )information.

[0071] (3) Since the sensitivity of the magnetic sensitive magnetoresistive sensor unit is proportional to the input voltage at the same ambient temperature, the sensitivity of the magnetic sensitive magnetoresistive sensor unit can be compensated by adjusting the input voltage so that the sensitivity after compensation is the target sensitivity. 1 ) and the first input voltage V cc The ratio should be equal to the compensated sensitivity (Starget-S(T 1 )) and the compensated input voltage V cs (T 1 ) have the same ratio, that is Therefore, the compensation input voltage V can be calculated based on the above cs (T 1 ).

[0072] The process of determining the load current of the conductor to be tested in the embodiment of the present invention includes:

[0073] (1) Since the difference in the output signals of the magnetoresistive sensing unit and the compensating magnetoresistive sensing unit of this embodiment is a constant when the magnetic field is zero, that is, the load current of the conductor to be measured is zero, the zero-point temperature drift of the two units presents the same trend.

[0074] (2) At the same temperature, the output signal change trend of the magnetoresistive sensing unit is the same as the output signal change trend of the compensating magnetoresistive sensing unit. The zero-point temperature drift signal S(T 1 The ratio of the zero-point temperature drift signal of the magnetic sensitive magnetoresistive sensor unit to the real output signal U of the magnetic sensitive magnetoresistive sensor unit meets the formula: U = U 2 (T 1 )-Z(T1 )×α.

[0075] The magnetic sensitive magnetoresistive sensing unit and the compensating magnetoresistive sensing unit of the embodiment of the present invention can realize magnetic field measurement based on the same magnetoresistive effect, and the α value is only related to the input voltage of the magnetic sensitive magnetoresistive sensing unit and the compensating magnetoresistive sensing unit. Specifically, when the magnetic sensitive magnetoresistive sensing unit and the compensating magnetoresistive sensing unit are composed of the same material, based on the existence of the input signal and the output signal of the magnetic sensitive magnetoresistive sensing unit and the compensating magnetoresistive sensing unit when the magnetic field is zero: U 0 (T 1 ) is the output signal of the magnetic sensitive magnetoresistive sensing unit when the magnetic field is zero. Therefore, the real output signal U of the magnetic sensitive magnetoresistive sensing unit conforms to the formula:

[0076]

[0077] (3) The load current I of the conductor to be tested conforms to the formula: Where Z(T 1 ) is the first signal; U 2 (T 1 ) is the second signal; V cs (T 1 ) is the compensation input voltage; V cc is the first input voltage; V 1 is the input voltage of the compensating magnetoresistive sensing unit; S 目标 The sensitivity mentioned here is the proportional relationship between the output signal of the magnetic sensitive magnetoresistive sensor unit and the current change of the current to be measured.

[0078] Therefore, the load current of the conductor to be tested can be determined based on the compensated input voltage, the first signal, the second signal and the pre-stored information.

[0079] refer to Figure 2 , Figure 2 The zero-point temperature drift curve and sensitivity change curve of the uncompensated comparative example of the current sensor of the present invention at various ambient temperatures are shown.

[0080] like Figure 2 As shown in the figure, when the ambient temperature is in the range of -40 to 125℃, the output signal of the magnetic sensitive magnetoresistive sensor unit under zero magnetic field, i.e., the zero-point temperature drift, decreases monotonically with temperature, from about 80mV to about -60mV, and the sensitivity of the magnetic sensitive magnetoresistive sensor unit also decreases monotonically with temperature, from about 40mV / A to about 38mV / A, indicating that the current sensor has large zero-point temperature drift and sensitivity temperature drift, and temperature has a great influence on the current measurement of the magnetic sensitive magnetoresistive sensor unit. Without temperature compensation, its measurement accuracy is difficult to meet the measurement requirements.

[0081] See also Figure 3 , Figure 3 1 is a zero point temperature drift curve diagram and a sensitivity change curve diagram of a current sensor under various ambient temperatures according to an embodiment of the present invention.

[0082] The current sensor uses the sensitivity of the magnetic sensitive magnetoresistive sensing unit (40mV / A) at 25°C as the target sensitivity, and the input voltage consists of the first input voltage and the compensation input voltage. When the ambient temperature of the compensated current sensor is in the range of -40 to 125°C, its zero temperature drift is kept within a few millivolts, and the sensitivity is basically kept at 40mV / A. Compared with the uncompensated current sensor, its zero temperature drift and sensitivity temperature drift are greatly reduced. This shows that the current sensor has high sensitivity for current measurement and can achieve a high accuracy for current measurement.

[0083] See also Figure 4 , Figure 4 This is a graph showing how the output voltage of a current sensor used for AC current measurement and the current signal of a conductor to be measured vary with time according to one embodiment of the present invention.

[0084] It should be understood that the load current in the conductor to be measured in the embodiment of the present invention is alternating current, and the current signal variation with time curve is obtained by contact measurement of the conductor to be measured. The curve is in the form of a sine wave, fluctuating around I=0A, and the position difference between each crest and trough is small, indicating that the zero-point temperature drift of the current signal obtained by this method is small. The voltage signal variation with time curve is obtained by measuring the current sensor of the embodiment of the present invention. The curve is also in the form of a sine wave, fluctuating around U=0mV, and the position difference between each crest and trough is small, indicating that the current signal obtained by non-contact measurement of the embodiment of the present invention achieves a small zero-point temperature drift. It shows that the current sensor can achieve better current measurement and has higher measurement accuracy.

[0085] To sum up, the current sensor of the embodiment of the present invention achieves a measurement result close to the true value through the synergistic effect of the compensating magnetoresistive sensing unit, the magnetically sensitive magnetoresistive sensing unit and the control unit, after considering the sensitivity compensation and the zero-point temperature drift compensation, thereby reducing the influence of the temperature factor on the current measurement result and improving the measurement accuracy.

[0086] In the embodiment of the present invention, the resistance of the magnetoresistive sensing unit has different resistances under different external magnetic fields, and its output signal varies with the external magnetic field. Preferably, the magnetic sensitivity direction of the magnetoresistive sensing unit is parallel to the magnetic field direction of the external magnetic field.

[0087] In the embodiment of the present invention, the compensating magnetoresistive sensing unit has the same or similar material as the magnetic sensitive magnetoresistive sensing unit, and its resistance can have the same or almost constant resistance under different external magnetic fields, and its output signal does not change with the external magnetic field. When the magnetic sensitive direction of the compensating magnetoresistive sensing unit is perpendicular to the magnetic field direction of the external magnetic field, the compensating magnetoresistive sensing unit cannot respond to the external magnetic field. In addition, when the compensating magnetoresistive magnetoresistive sensing unit is in a magnetic saturation state, such as when a permanent magnet is placed around the compensating magnetoresistive sensing unit, the compensating magnetoresistive sensing unit is also unable to respond to the external magnetic field.

[0088] It should be understood that the reasons causing the compensated magnetoresistive sensor unit to be insensitive to the nearby magnetic field are not limited to the above two reasons, and may also be other situations.

[0089] In the embodiment of the present invention, the compensating magnetoresistive sensing unit and the magnetosensitive magnetoresistive sensing unit are both Wheatstone full-bridge structures. Since the compensating magnetoresistive sensing unit and the magnetosensitive magnetoresistive sensing unit are easily affected by factors such as noise, the stability of the output signals of the compensating magnetoresistive sensing unit and the magnetosensitive magnetoresistive sensing unit after forming the Wheatstone full-bridge structure can be greatly improved.

[0090] Furthermore, the control unit of the embodiment of the present invention includes a storage module, an acquisition module, a determination module and an adjustment module.

[0091] The storage module is used to store the first corresponding relationship Z(T) between the first signal of the compensation magnetoresistive sensing unit and the temperature, the second corresponding relationship S(T) between the sensitivity of the magnetoresistive sensing unit and the temperature, the first input voltage V cc and target sensitivity S 目标 The acquisition module is used to acquire the current first signal Z(T 1 ), the current second signal U output by the magnetoresistive sensing unit 2 (T 1 The determination module is used to determine the current first signal Z(T 1 ), the first stored correspondence Z(T) determines the current ambient temperature T 1 The adjustment module is used to send instructions to adjust the current input voltage of the magnetic sensitive magnetoresistive sensor unit to the first input voltage V cc With the current compensation input voltage V cs (T 1 The determination module is also used to determine the current ambient temperature T 1 and the pre-stored second corresponding relationship S(T) to determine the current sensitivity S(T) of the magnetic sensitive magnetoresistive sensing unit 1 ).

[0092] Furthermore, the determination module is also used to determine the current compensation input voltage according to the current sensitivity, the pre-stored target sensitivity and the first input voltage; wherein the current compensation input voltage V cs (T 1 ) conforms to the formula: S 目标 is the target sensitivity; S 当前 is the current sensitivity; V cc is the first input voltage.

[0093] Furthermore, the determination module is also used to determine the load current of the conductor to be measured according to the current second signal and the current first signal after the current input voltage is adjusted to the sum of the first input voltage and the current compensation input voltage.

[0094] Furthermore, the determination module is also used to determine whether a first signal change rate of the compensated magnetoresistive sensing unit is higher than a first threshold value according to each current first signal of the compensated magnetoresistive sensing unit.

[0095] Furthermore, the adjustment module is also used to send an instruction to adjust the current input voltage of the magnetic sensitive magnetoresistive sensing unit when the first signal change rate of the compensation magnetoresistive sensing unit is higher than a first threshold.

[0096] Specifically, the number of changes of the current input voltage is controlled by the first signal change rate, that is, the current input voltage is adjusted only when a relatively large change occurs in the ambient temperature, which can greatly reduce the number of adjustments of the adjustment module.

[0097] Considering that the temperature of the external environment cannot be in a large fluctuation for a long time, through this step, the input voltage of the magnetic sensitive magnetoresistive sensor unit is adjusted only when the measurement is just started or the temperature fluctuates, so as to avoid repeated execution of invalid instructions.

[0098] To achieve the purpose of the present invention, an embodiment of the present invention further provides a current measurement method, which is applied to the above-mentioned current sensor to further improve the problem that the current sensor has low current measurement accuracy under different ambient temperatures.

[0099] In some embodiments of the present invention, the current measurement method comprises the following steps:

[0100] Step S100: obtaining a current first signal output by a compensation magnetoresistive sensing unit;

[0101] Specifically, in this step, the control unit receives the current first signal output by the compensation magnetoresistive sensing unit around the conductor to be tested. The current first signal does not change with the change of the external magnetic field. The current first signal can be regarded as the temperature drift of the compensation magnetoresistive sensing unit at the current temperature.

[0102] It should be noted that the compensating magnetoresistive sensing unit is in a magnetic saturation state or in an insensitive position, such as making its magnetic sensitivity direction parallel to the current direction of the conductor to be measured, thereby making the compensating magnetoresistive sensing unit unable to respond to the external magnetic field.

[0103] Step S200: determining the current ambient temperature according to the current first signal and a pre-stored first correspondence between the first signal of the compensation magnetoresistive sensor unit and the temperature;

[0104] Specifically, in this step, the control unit obtains the current ambient temperature information by looking up a table or the like according to the received current first signal and the pre-stored first correspondence between the first signal of the compensated magnetoresistive sensor unit and the temperature.

[0105] It should be noted that the first corresponding relationship between the first signal of the compensated magnetoresistive sensor unit and the temperature may be an empirical formula or a corresponding relationship obtained by fitting a plurality of test data in advance, which is not specifically limited here.

[0106] Step S300: determining the current sensitivity of the magnetic-sensitive magnetoresistive sensor unit according to the current ambient temperature and a pre-stored second corresponding relationship between the sensitivity of the magnetic-sensitive magnetoresistive sensor unit and the temperature;

[0107] Specifically, in this step, the control unit obtains the current sensitivity of the magnetic-sensitive magnetoresistive sensor unit by looking up a table based on the current ambient temperature obtained in S200 and the pre-stored second corresponding relationship between the sensitivity of the magnetic-sensitive magnetoresistive sensor unit and the temperature.

[0108] It should be noted that the second corresponding relationship between the sensitivity of the magnetic-sensitive magnetoresistive sensor unit and the temperature is that the magnetic-sensitive magnetoresistive sensor unit is tested under the premise that the input voltage is the first input voltage, and its curve of change with the magnetic field is tested at different temperatures, and the sensitivity of the magnetic-sensitive magnetoresistive sensor unit at multiple ambient temperatures is obtained from each magnetic field change curve, and then the second corresponding relationship is obtained by data fitting. The second corresponding relationship conforms to a multi-order function, such as a fourth-order function, a fifth-order function or a higher-order function.

[0109] Step S400: Determine the current compensation input voltage according to the current sensitivity, the pre-stored target sensitivity of the magnetic sensitive magnetoresistive sensor unit and the first input voltage of the magnetic sensitive magnetoresistive sensor unit; wherein the current compensation input voltage V cs (T 1 ) conforms to the formula: S 目标 is the target sensitivity; S 当前 is the current sensitivity; V cc is the first input voltage;

[0110] Specifically, this step is performed by the control unit according to the formula: The current sensitivity S obtained in step S300当前 and the target sensitivity S of the pre-stored magnetic sensitive magnetoresistive sensing unit 目标 , the first input voltage V of the magnetoresistive sensing unit in , determine the current compensation input voltage V cs (T 1 );

[0111] Step S500: adjusting the current input voltage of the magnetic-sensitive magnetoresistive sensor unit to be the sum of the first input voltage and the current compensation input voltage, and obtaining the current second signal output by the magnetic-sensitive magnetoresistive sensor unit;

[0112] Specifically, in this step, the control unit can use hardware, such as an adder, to convert the input voltage of the magnetic sensitive magnetoresistive sensor unit into the first input voltage V cc Add V on the basis cs (T 1 ).

[0113] Step S600: Determine the load current of the conductor to be tested according to the current compensated magnetic resistance sensor unit, the current second signal and the current first signal.

[0114] Specifically, in this step, the control unit can calculate through hardware or software, according to the empirical formula, such as Then the load current of the conductor to be tested is obtained.

[0115] In one embodiment of the present invention, the current measurement method includes:

[0116] Step S010: obtaining a first corresponding relationship between a first signal of a compensation magnetoresistive sensing unit and temperature;

[0117] Specifically, it includes: first testing the output signal of the compensated magnetoresistance sensor unit at multiple ambient temperatures, such as -50 to 100°C, to obtain first test data; then constructing a first fitting relationship curve between the output signal of the compensated magnetoresistance sensor unit and the temperature based on the first test data; finally, determining the first corresponding relationship between the first signal of the compensated magnetoresistance sensor unit and the temperature based on the fitting relationship curve.

[0118] In the embodiment of the present invention, the first fitting relationship curve is as follows: Figure 2 The first fitting relationship curve conforms to a multi-order function, and the first signal has a monotonically decreasing trend as the temperature increases.

[0119] In the embodiment of the present invention, the first fitting relationship curve conforms to a multi-order function, and the multi-order function can be a third-order function, a fourth-order function, a fifth-order function or a higher-order function. Here, the multi-order function conforms to the formula:

[0120] Z(T)=b m T m +bm-1 T m-1 +…+b 2 T 2 +b 1 T+b 0 ;

[0121] Wherein, Z(T) is the current first signal output by the compensation magnetoresistive sensing unit when the ambient temperature is T, b m is an integer, and m is a natural number greater than 2.

[0122] Step S020: obtaining a second corresponding relationship between the sensitivity of the magnetic sensitive magnetoresistive sensor unit and the temperature.

[0123] Specifically, the method includes: firstly testing the change of a magnetic field with a magnetic-sensitive magnetoresistive sensing unit at multiple ambient temperatures to obtain second test data, wherein the value of the input voltage of the magnetic-sensitive magnetoresistive sensing unit at this time is the first input voltage; then, based on the second test data, constructing a second fitting relationship curve between the sensitivity and temperature of the magnetic-sensitive magnetoresistive sensing unit; and finally, determining a second corresponding relationship between the sensitivity and temperature of the magnetic-sensitive magnetoresistive sensing unit based on the second fitting relationship curve.

[0124] In this embodiment, the second test data includes the corresponding relationship between the output signal of the magnetic-sensitive magnetoresistive sensing unit under different magnetic fields, and also includes the corresponding relationship between the load current of the conductor to be tested and the surrounding magnetic field; based on the corresponding relationship between the output signal of the magnetic-sensitive magnetoresistive sensing unit under different magnetic fields, the first sensitivity, that is, the ratio of the output signal to the magnetic field, is obtained; based on the corresponding relationship between the load current of the conductor to be tested and the surrounding magnetic field, the second sensitivity, that is, the ratio of the magnetic field to the load current, is obtained; therefore, the sensitivity of the magnetic-sensitive magnetoresistive sensing unit at the current temperature is the product of the first sensitivity and the second sensitivity.

[0125] In the embodiment of the present invention, the second fitting relationship curve conforms to a multi-order function, and the multi-order function can be a third-order function, a fourth-order function, a fifth-order function or a higher-order function. Here, the multi-order function conforms to the formula:

[0126] S(T)=a m T m +a m-1 T m-1 +…+a 2 T 2 +a 1 T+a 0 ;

[0127] Where S(T) is the current sensitivity of the magnetic sensitive magnetoresistive sensor unit when the ambient temperature is T, a m is an integer, and m is a natural number greater than 2.

[0128] It should be noted that the accuracy of the current measurement result is related to the multi-order function. The higher the order of the multi-order function, the higher the accuracy of the current measurement result obtained by the current measurement method of the present invention.

[0129] S030 acquiring a current first signal output by the compensation magnetic resistance sensing unit;

[0130] In this embodiment, the compensating magnetoresistive sensing unit and the magnetically sensitive magnetoresistive sensing unit are made of the same material. Its input voltage is the same as the first voltage of the magnetically sensitive magnetoresistive sensing unit. The magnetically sensitive direction of the compensating magnetoresistive sensing unit is parallel to the current direction of the conductor to be measured. When the load current of the conductor to be measured is zero, the output of the compensating magnetoresistive sensing unit remains constant under any external magnetic field.

[0131] S040 determining the current ambient temperature according to the current first signal and a first correspondence between the first signal of the compensated magnetic resistance sensor unit and the temperature obtained in advance;

[0132] Specifically, the value of the current first signal is substituted into the first corresponding relationship to obtain the current ambient temperature.

[0133] S050 determines the current sensitivity of the magnetic-sensitive magnetoresistive sensor unit according to the current ambient temperature and a pre-stored second corresponding relationship between the sensitivity of the magnetic-sensitive magnetoresistive sensor unit and the temperature;

[0134] Specifically, the value of the current ambient temperature is substituted into the second corresponding relationship to obtain the current sensitivity of the magnetic-sensitive magnetoresistive sensor unit.

[0135] S060 is based on the formula: The current sensitivity S obtained in step S300 当前 And the pre-stored target sensitivity S 目标 , the first input voltage V of the magnetoresistive sensing unit cc , determine the current compensation input voltage V cs (T 1 );

[0136] Specifically, the current sensitivity and the previous data are substituted into the formula Get the value of the current compensation input voltage.

[0137] S070: adjusting the current input voltage of the magnetic-sensitive magnetoresistive sensor unit to the sum of the first input voltage and the current compensation input voltage, and obtaining the current second signal output by the magnetic-sensitive magnetoresistive sensor unit;

[0138] Specifically, the current input voltage of the magnetic sensitive magnetoresistive sensing unit is compensated in real time, and the second signal U output by the compensated magnetic sensitive magnetoresistive sensing unit is obtained. 2 (T 1 ).

[0139] S080 will compensate the current input voltage V cs (T 1 ), the current first signal Z(T 1 ), the current second signal U 2 (T 1 ), target sensitivity and pre-stored target sensitivity Starget, compensated input voltage V 1 And the first input voltage V of the magnetoresistive sensing unit cc , put it into the formula:

[0140] Get the load current I of the conductor to be tested.

[0141] In addition, to achieve the above objectives, the present invention also proposes a current measuring device, which includes: a memory, a processor, and a current measuring program stored in the memory and executable on the processor, wherein the current measuring program is configured to implement the steps of the current measuring method as described above.

[0142] Since the current measuring device adopts all the technical solutions of all the above embodiments, it has at least all the beneficial effects brought by the technical solutions of the above embodiments, which will not be described one by one here.

[0143] In addition, an embodiment of the present invention further provides a storage medium, on which a current measurement program is stored. When the current measurement program is executed by a processor, the steps of the current measurement method described above are implemented.

[0144] Since the storage medium adopts all the technical solutions of all the above embodiments, it has at least all the beneficial effects brought by the technical solutions of the above embodiments, which will not be described one by one here.

[0145] It should be understood that the above is only an example and does not constitute any limitation on the technical solution of the present invention. In specific applications, technicians in this field can make settings as needed, and the present invention does not limit this.

[0146] It should be noted that the workflow described above is merely illustrative and does not limit the scope of protection of the present invention. In practical applications, technicians in this field can select part or all of them according to actual needs to achieve the purpose of the present embodiment, and no limitation is made here.

[0147] In addition, for technical details that are not described in detail in this embodiment, reference can be made to the engineering mode control method provided in any embodiment of the present invention, and will not be repeated here.

[0148] In addition, it should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or system including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or system. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or system including the element.

[0149] The serial numbers of the above embodiments of the present invention are only for description and do not represent the advantages or disadvantages of the embodiments.

[0150] Through the description of the above implementation methods, those skilled in the art can clearly understand that the above-mentioned embodiment methods can be implemented by means of software plus a necessary general hardware platform, and of course by hardware, but in many cases the former is a better implementation method. Based on such an understanding, the technical solution of the present invention is essentially or the part that contributes to the prior art can be embodied in the form of a software product, which is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk) as described above, and includes a number of instructions for a terminal device (which can be a mobile phone, a computer, a server, or a network device, etc.) to execute the methods described in each embodiment of the present invention.

[0151] The above are only preferred embodiments of the present invention, and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A current sensor, characterized in that: include: A compensating magnetic resistance sensing unit, used for sensing the temperature around the conductor to be measured and outputting a first signal; The first signal varies monotonically only with temperature; A magnetoresistive sensing unit, used for sensing the magnetic field around the conductor to be measured and outputting a second signal; when the load current of the conductor to be measured is zero, the difference between the second signal and the first signal is a constant; A control unit, configured to determine a compensation input voltage of the magnetic-sensitive magnetoresistive sensor unit according to the first signal, adjust the input voltage of the magnetic-sensitive magnetoresistive sensor unit to be the sum of the first input voltage and the compensation input voltage so that the sensitivity of the magnetic-sensitive magnetoresistive sensor unit does not change with temperature, and determine a load current of the conductor to be measured according to the compensation input voltage, the second signal and the first signal; The process of determining the compensation input voltage of the magnetic sensitive magnetoresistive sensing unit includes: Determine the current ambient temperature according to a first corresponding relationship between the first signal of the compensated magnetoresistance sensor unit and the temperature and a first signal currently output by the compensated magnetoresistance sensor unit; Determining the current sensitivity of the magnetically sensitive magnetoresistive sensing unit according to the second corresponding relationship between the sensitivity and temperature of the magnetically sensitive magnetoresistive sensing unit and the current ambient temperature; According to the first input voltage V of the magnetoresistive sensing unit cc , the target sensitivity S of the magnetoresistive sensing unit 目标 , the current sensitivity S 当前 And the formula: , determine the compensation input voltage V of the magnetic sensitive magnetoresistive sensing unit cs (T1); The process of determining the load current of the conductor to be tested includes: According to the formula: , determine the load current I; Wherein Z(T1) is the first signal; U2 (T1) is the second signal; V1 is the input voltage of the compensated magnetoresistive sensing unit.

2. The current sensor according to claim 1, characterized in that: The magnetic sensitive magnetoresistive sensing unit and the compensating magnetoresistive sensing unit are both Wheatstone full-bridge structures; The magnetic sensitivity direction of the magnetic sensitive magnetoresistive sensing unit is parallel to the direction of the magnetic field around it; The magnetic sensitivity direction of the compensation magnetoresistive sensing unit is perpendicular to the direction of the magnetic field around it, or the compensation magnetoresistive sensing unit is in a magnetic saturation state.

3. The current sensor according to claim 1 or 2, characterized in that: The control unit comprises: A storage module, used for storing the first corresponding relationship, the input voltage of the compensated magnetoresistive sensing unit, the second corresponding relationship, the first input voltage and the target sensitivity; An acquisition module, used for acquiring the current first signal output by the compensating magnetoresistive sensing unit and the current second signal output by the magnetoresistive magnetoresistive sensing unit; A determination module, configured to determine the current ambient temperature according to the current first signal and the pre-stored first corresponding relationship; An adjustment module, used for sending instructions to adjust the current input voltage of the magnetic sensitive magnetoresistive sensor unit to the sum of the first input voltage and the current compensation input voltage; The determination module is further used to determine the current sensitivity of the magnetic sensitive magnetoresistive sensing unit according to the current ambient temperature and the second pre-stored corresponding relationship; The determination module is further configured to determine the current compensation input voltage according to the current sensitivity, the pre-stored target sensitivity and the first input voltage; wherein the current compensation input voltage V cs (T1) complies with the formula: , S 目标 is the target sensitivity; S 当前 is the current sensitivity; V cc is the first input voltage; The determination module is also used according to the formula: , determine the load current of the conductor to be measured, wherein Z(T1) is the first signal; U2 (T1) is the second signal; V1 is the input voltage of the compensated magnetic resistance sensor unit.

4. A current measurement method, characterized in that: A current sensor applied to any one of claims 1 to 3; the method comprising: Acquiring a current first signal output by the compensating magnetic resistance sensing unit; Determine the current ambient temperature according to the current first signal and a pre-stored first correspondence between the first signal of the compensated magnetoresistive sensing unit and the temperature; Determining the current sensitivity of the magnetic-sensitive magnetoresistive sensor unit according to the current ambient temperature and a pre-stored second corresponding relationship between the sensitivity of the magnetic-sensitive magnetoresistive sensor unit and the temperature; The current compensation input voltage is determined according to the current sensitivity, the pre-stored target sensitivity of the magnetic sensitive magnetoresistive sensing unit and the first input voltage of the magnetic sensitive magnetoresistive sensing unit; wherein the current compensation input voltage V cs (T1) complies with the formula: , S 目标 is the target sensitivity; S 当前 is the current sensitivity; V cc is the first input voltage; Adjusting the current input voltage of the magnetic-sensitive magnetoresistive sensing unit to be the sum of the first input voltage and the current compensation input voltage, and acquiring the current second signal output by the magnetic-sensitive magnetoresistive sensing unit; According to the compensation input voltage V cs (T1), the current second signal U2 (T1) and the current first signal Z(T1), determine the load current of the conductor to be tested, wherein the load current I meets the formula: , where V1 is the input voltage of the compensated magnetoresistive sensing unit.

5. The current measurement method according to claim 4, characterized in that: The step of adjusting the current input voltage of the magnetic sensitive magnetoresistive sensing unit to be the sum of the first input voltage and the current compensation input voltage includes: Acquiring a first signal change rate of the compensated magnetic resistance sensing unit; Determining whether the first signal change rate is higher than a first threshold; When the first signal change rate is higher than the first threshold, the current input voltage of the magnetic-sensitive magnetoresistive sensing unit is adjusted to be the sum of the first input voltage and the current compensation input voltage.

6. The method according to claim 4, characterized in that The method further comprises: Acquire a first corresponding relationship between a first signal of the compensating magnetoresistive sensing unit and a temperature; Acquire a second corresponding relationship between the sensitivity of the magnetic sensitive magnetoresistive sensing unit and the temperature; The obtaining of a first corresponding relationship between the first signal of the compensated magnetoresistive sensing unit and the temperature includes: Testing the output signal of the compensated magnetoresistive sensor unit under multiple ambient temperatures to obtain first test data; Constructing a first fitting relationship curve between the output signal of the compensation magnetoresistive sensing unit and the temperature according to the first test data; Determining a first corresponding relationship between a first signal of the compensated magnetic resistance sensing unit and temperature according to the fitting relationship curve; The obtaining of a second corresponding relationship between the sensitivity of the magnetic sensitive magnetoresistive sensing unit and the temperature includes: Testing the change of the magnetic field of the magnetic sensitive magnetoresistive sensor unit under multiple ambient temperatures to obtain second test data; the input voltage of the magnetic sensitive magnetoresistive sensor unit is the first input voltage; Constructing a second fitting relationship curve between the sensitivity and temperature of the magnetic sensitive magnetoresistive sensing unit according to the second test data; According to the second fitting relationship curve, a second corresponding relationship between the sensitivity of the magnetic-sensitive magnetoresistive sensor unit and the temperature is determined.

7. The method according to claim 6, characterized in that The first fitting relationship curve conforms to a first multi-order function; the second fitting relationship curve conforms to a second multi-order function.

8. A current measuring device, characterized in that: The device comprises: a memory, a processor, and a current measurement program stored in the memory and running on the processor, wherein the current measurement program is configured to implement the steps of the current measurement method according to claims 4-7.

9. A storage medium, characterized in that: The storage medium stores a current measurement program, and when the current measurement program is executed by the processor, the steps of the current measurement method according to claims 4 to 7 are implemented.

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