CN116699223A - Current detection system and method based on TMR sensor - Google Patents
Current detection system and method based on TMR sensor Download PDFInfo
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/0092—Arrangements for measuring currents or voltages or for indicating presence or sign thereof measuring current only
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R15/00—Details of measuring arrangements of the types provided for in groups G01R17/00 - G01R29/00, G01R33/00 - G01R33/26 or G01R35/00
- G01R15/14—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks
- G01R15/20—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using galvano-magnetic devices, e.g. Hall-effect devices, i.e. measuring a magnetic field via the interaction between a current and a magnetic field, e.g. magneto resistive or Hall effect devices
- G01R15/205—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using galvano-magnetic devices, e.g. Hall-effect devices, i.e. measuring a magnetic field via the interaction between a current and a magnetic field, e.g. magneto resistive or Hall effect devices using magneto-resistance devices, e.g. field plates
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
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- G01R19/32—Compensating for temperature change
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Abstract
The invention discloses a current detection system and a current detection method based on a TMR sensor, wherein the current detection system comprises the following steps: the device comprises an annular iron core with an air gap, a first TMR sensor, a second TMR sensor, a third TMR sensor, a differential amplification system and a data processing system, wherein the annular iron core is positioned in a first magnetic field and provided with the air gap; the first magnetic field is generated by a current to be measured passing through the center of the annular iron core, and the magnetic field sensitivity direction of the first TMR sensor is opposite to the magnetic field sensitivity direction of the second TMR sensor and is the same as the direction of the first magnetic field; the differential amplification system is used for respectively carrying out differential amplification on the output voltages of the three TMR sensors to obtain corresponding voltage data; and the data processing system is used for analyzing all the voltage data and outputting fourth voltage data capable of reflecting the magnitude of the current to be measured. The invention realizes temperature and bias voltage compensation on the premise of not obtaining the temperature characteristic and bias characteristic of the TMR sensor.
Description
Technical Field
The invention relates to the field of TMR sensor power detection, in particular to a current detection system and method based on a TMR sensor.
Background
With deployment and promotion of smart grids and ubiquitous power internet of things, a power system has higher requirements on a current sensing technology. The types of current required to be measured by the power system are very many, and the technical requirements of the current measurement of the power system are difficult to fully meet by using the existing single current transformer. The Tunnel Magnetoresistance (TMR) current sensor has the advantages of high sensitivity, high response frequency, simple structure, low price and the like, and is a product with great potential for measuring the current of an electric power system. However, the sensitivity of the TMR sensor has a strong temperature dependence, and has a great influence on measurement accuracy. Besides, the TMR chip generally adopts a bridge structure, and because of the process limitation, the initial values of four resistors in the TMR chip cannot be guaranteed to be completely consistent, and meanwhile, the TMR chip is influenced by surrounding stray magnetic fields and the like, and the fixed output bias voltage exists on the TMR chip, so that the output result can be influenced.
The current temperature compensation method for the TMR sensor mainly comprises hardware compensation and software compensation. The hardware compensation is to connect a thermistor, a diode, a potentiometer and other elements with temperature coefficients into a sensor interface circuit, wherein the temperature coefficients are opposite to those of the sensor, the relation between the sensitivity, zero position and temperature of the sensor is determined during compensation, different circuit topological structures are selected according to the relation between the sensitivity and temperature characteristics, and finally the temperature compensation is realized through calculation and matching. And the software compensation is realized by matching a digital sensor microprocessor through a plurality of regression algorithms and performing data fusion processing on the output signals and the temperature signals of the acquisition sensor. The bias voltage compensation method of the TMR sensor is mainly realized through hardware compensation. The reference voltage input end of the subsequent instrument amplifier is connected with a control circuit with small output impedance and variable output voltage, and the offset voltage is compensated by adjusting the reference voltage. From the above, it can be seen that the hardware temperature compensation needs to obtain the temperature characteristic of the TMR sensor in advance, and the temperature coefficient of the thermistor needs to be matched with the temperature coefficient of the TMR when the thermistor is selected, so that only one sensor can be matched with a specific thermistor, engineering and batch production are difficult, and the software compensation method is similar to the hardware temperature compensation, and the temperature characteristic of the sensor needs to be obtained in advance, so that engineering and batch production are difficult to realize. As for offset voltage compensation, the offset is required to be obtained under zero input by connecting a voltage-adjustable control circuit consisting of a controllable resistor and an operational amplifier to the reference voltage input end of a subsequent amplifying circuit, and the working point is fixed, namely, the offset can be compensated only under a certain offset, and when the offset changes along with the temperature, the offset cannot be compensated.
Disclosure of Invention
The embodiment of the invention provides a current detection system and a method based on a TMR sensor, which can realize temperature compensation and bias voltage compensation of the TMR sensor without acquiring temperature characteristics and bias characteristics of the TMR sensor, thereby eliminating the influence of temperature and bias voltage on current detection precision.
In order to solve the above technical problems, an embodiment of the present invention provides a current detection system based on a TMR sensor, including: a toroidal core with an air gap, a first TMR sensor and a second TMR sensor placed in parallel in the air gap, a third TMR sensor placed in a constant magnetic field outside the toroidal core, a differential amplification system, and a data processing system;
wherein, the annular iron core and the air gap of the annular iron core are both in a first magnetic field; the first magnetic field is generated by current to be measured passing through the center of the annular iron core, the magnetic field sensitivity direction of the first TMR sensor is the same as the direction of the first magnetic field, and the magnetic field sensitivity direction of the second TMR sensor is opposite to the direction of the first magnetic field;
the differential amplification system is used for respectively carrying out differential amplification on the output voltage of the first TMR sensor, the output voltage of the second TMR sensor and the output voltage of the third TMR sensor to obtain first voltage data corresponding to the first TMR sensor, second voltage data corresponding to the second TMR sensor and third voltage data corresponding to the third TMR sensor;
the data processing system is used for analyzing and processing the first voltage data, the second voltage data and the third voltage data according to a preset logic algorithm and outputting fourth voltage data capable of reflecting the current value of the current to be measured.
According to the embodiment of the invention, the first TMR sensor and the second TMR sensor with opposite magnetic field sensitivity directions are placed in parallel in the air gap of the annular iron core, so that output voltage with opposite magnetic field directions and output voltage with same magnetic field directions generated by measured current passing through the center of the annular iron core are obtained, and the third TMR sensor for measuring a constant magnetic field is additionally arranged, so that output voltage corresponding to the constant magnetic field is obtained, differential amplification and operation processing are carried out on the output voltages of the three TMR sensors through a differential amplification system, and finally fourth voltage data capable of reflecting the current value of the current to be measured is output, so that the influence of the bias voltage of the TMR sensors can be eliminated, the temperature dependence of the sensitivity of the TMR sensors can be eliminated, the current value of the current to be measured can be directly known based on the fourth voltage data, the temperature compensation and bias voltage compensation of the sensor can be realized under the condition that the temperature characteristic and bias characteristic of the TMR sensor are not required to be acquired, the current detection accuracy of the current sensor is improved, the signal detection is reduced, and the current detection system is applicable to different current detection systems.
Preferably, the constant magnetic field is generated by a permanent magnet; wherein the permanent magnet and the third TMR sensor are both placed in a magnetic shield case.
According to the preferred scheme of the embodiment of the invention, the permanent magnet is used for providing a constant magnetic field, the permanent magnet and the third TMR sensor are both arranged in the magnetic shielding shell, and the constant magnetic field, the permanent magnet in the constant magnetic field and the third TMR sensor are magnetically shielded, so that the influence of other stray magnetic fields is avoided, and the influence of the bias voltage of the TMR sensor is further eliminated.
Preferably, the differential amplifying system includes: a first differential amplifier, a second differential amplifier, and a third differential amplifier;
the first differential amplifier is connected with the signal output end of the first TMR sensor and is used for carrying out differential amplification with the gain of the output voltage of the first TMR sensor being a first preset value to obtain first voltage data corresponding to the first TMR sensor;
the second differential amplifier is connected with the signal output end of the second TMR sensor and is used for carrying out differential amplification on the output voltage of the second TMR sensor, wherein the gain of the differential amplification is the first preset value, so as to obtain second voltage data corresponding to the second TMR sensor;
the third differential amplifier is connected with the signal output end of the third TMR sensor and is used for carrying out differential amplification on the output voltage of the third TMR sensor, wherein the gain of the differential amplification is a second preset value, and third voltage data corresponding to the third TMR sensor is obtained;
wherein the first preset value is equal to half of the second preset value.
According to the preferred scheme of the embodiment of the invention, the first differential amplifier and the second differential amplifier are respectively utilized to perform differential amplification with the gain of the output voltage of the first TMR sensor and the output voltage of the second TMR sensor being a first preset value, and the third differential amplifier is utilized to perform differential amplification with the gain of the output voltage of the third TMR sensor being twice the first preset value, so that the intensity and the definition of an output voltage signal are improved, noise in the output voltage signal is restrained, and the subsequent operation results based on the first voltage data output by the first differential amplifier, the second voltage data output by the second differential amplifier and the third voltage data output by the third differential amplifier are convenient, and the fourth voltage data capable of reflecting the current value of the current to be measured is accurately deduced.
Preferably, the data processing system includes: the system comprises a first subtracter, an adder, a second subtracter and a divider;
the first subtracter is used for subtracting the first voltage data from the second voltage data to obtain a corresponding first operation result, and transmitting the first operation result to the divider;
the adder is configured to add the first voltage data and the second voltage data to obtain a corresponding second operation result, and transmit the second operation result to the second subtractor;
the second subtracter is used for subtracting the third voltage data from the second operation result to obtain a corresponding third operation result, and transmitting the third operation result to the divider;
the divider is configured to divide the first operation result by the third operation result to obtain the fourth voltage data.
According to the preferred scheme of implementing the embodiment of the invention, through the first subtracter, the adder, the second subtracter and the divider, the differential amplification results of the output voltages of the first TMR sensor, the second TMR sensor and the third TMR sensor are subjected to corresponding operation processing, so that a voltage signal proportional to the current value of the current to be detected is obtained, and the current value of the current to be detected is directly obtained based on fourth voltage data.
In order to solve the same technical problems, the embodiment of the invention also provides a current detection method based on a TMR sensor, which comprises the following steps:
when current to be measured passes through the center of an annular iron core with an air gap, a first TMR sensor and a second TMR sensor are respectively utilized to detect a first magnetic field generated by the current to be measured, so as to obtain the output voltage of the first TMR sensor and the output voltage of the second TMR sensor, and a third TMR sensor is utilized to detect a constant magnetic field, so as to obtain the output voltage of the third TMR sensor;
differential amplification is carried out on the output voltage of the first TMR sensor, the output voltage of the second TMR sensor and the output voltage of the third TMR sensor respectively through a differential amplification system, so that first voltage data corresponding to the first TMR sensor, second voltage data corresponding to the second TMR sensor and third voltage data corresponding to the third TMR sensor are obtained;
according to a preset logic algorithm, analyzing the first voltage data, the second voltage data and the third voltage data, and outputting fourth voltage data capable of reflecting the magnitude of the current value of the current to be measured;
the first TMR sensor and the second TMR sensor are arranged in parallel in an air gap of the annular iron core, the magnetic field sensitivity direction of the first TMR sensor is the same as the direction of the first magnetic field, the magnetic field sensitivity direction of the second TMR sensor is opposite to the direction of the first magnetic field, the annular iron core and the air gap of the annular iron core are both in the first magnetic field, and the third TMR sensor is arranged in the constant magnetic field outside the annular iron core.
Preferably, the constant magnetic field is generated by a permanent magnet; wherein the permanent magnet and the third TMR sensor are both placed in a magnetic shield case.
As a preferred solution, the differential amplifying system is configured to differentially amplify the output voltage of the first TMR sensor, the output voltage of the second TMR sensor, and the output voltage of the third TMR sensor to obtain first voltage data corresponding to the first TMR sensor, second voltage data corresponding to the second TMR sensor, and third voltage data corresponding to the third TMR sensor, where the differential amplifying system is specifically:
performing differential amplification with the gain of the output voltage of the first TMR sensor being a first preset value by using a first differential amplifier in the differential amplification system to obtain first voltage data corresponding to the first TMR sensor;
performing differential amplification with the gain of the output voltage of the second TMR sensor being the first preset value by using a second differential amplifier in the differential amplification system to obtain second voltage data corresponding to the second TMR sensor;
performing differential amplification with the gain of the output voltage of the third TMR sensor being a second preset value by using a third differential amplifier in the differential amplification system to obtain third voltage data corresponding to the third TMR sensor;
the first preset value is equal to half of the second preset value, the first differential amplifier is connected with the signal output end of the first TMR sensor, the second differential amplifier is connected with the signal output end of the second TMR sensor, and the third differential amplifier is connected with the signal output end of the third TMR sensor.
As a preferred solution, the analyzing the first voltage data, the second voltage data and the third voltage data according to a preset logic algorithm, and outputting fourth voltage data capable of reflecting the magnitude of the current value of the current to be measured, specifically includes:
subtracting the first voltage data from the second voltage data to obtain a corresponding first operation result, and adding the first voltage data and the second voltage data to obtain a corresponding second operation result;
and subtracting the third voltage data from the second operation result to obtain a corresponding third operation result, and dividing the first operation result by the third operation result to obtain the fourth voltage data.
Drawings
Fig. 1: the first embodiment of the invention provides a structural schematic diagram of a current detection system based on a TMR sensor;
fig. 2: the first embodiment of the invention provides a flow diagram of a current detection method based on a TMR sensor.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Embodiment one:
referring to fig. 1, a schematic structural diagram of a current detection system based on a TMR sensor according to an embodiment of the present invention is shown, where the system includes: a toroidal core 1 with an air gap, a first TMR sensor 2 and a second TMR sensor 3 placed in parallel in the air gap, a constant magnetic field B placed outside the toroidal core 1 0 A third TMR sensor 4, a differential amplification system 5, and a data processing system 6.
Preferably, the magnetic field B is constant 0 Is produced by a permanent magnet; wherein the permanent magnet and the third TMR sensor 4 are both disposed in a magnetic shield case 7, and the magnetic shield case 7 is composed of a high permeability material so as to be in a constant magnetic field B 0 The inner permanent magnet and the third TMR sensor 4 are not affected by other stray magnetic fields from the outside.
As can be seen from the operation characteristics of the TMR sensor, the mathematical relationship between the output voltage of the TMR sensor and the magnetic field in which the output voltage is located is shown in the expression (1).
U＝k(T)BV in +b 0 (1)
Wherein U represents the output voltage of the TMR sensor; k (T) represents the sensitivity of the TMR sensor, which varies with a variation in temperature T; b represents the magnetic field where the TMR sensor is located; v (V) in Representing the supply voltage of the TMR sensor; b 0 Representing the zero bias voltage of the TMR sensor.
In the present embodiment, the toroidal core 1 and the air gap of the toroidal core 1 are both in the first magnetic field B 1 In (a) and (b); wherein the first magnetic field B 1 Is the current to be measured passing through the center of the toroidal core 1I P The magnetic field sensitivity direction of the first TMR sensor 2 is generated to be equal to the first magnetic field B 1 The direction of the magnetic field sensitivity of the second TMR sensor 3 is the same as the first magnetic field B 1 Is opposite to the direction of the (c).
In this embodiment, the first TMR sensor 2, the second TMR sensor 3, and the third TMR sensor 4 are the same model, the same lot of products, and the three TMR sensors are powered by the same power source, and the sensitivity, the power supply voltage, and the zero bias voltage of the first TMR sensor 2, the second TMR sensor 3, and the third TMR sensor 4 are the same. From the operating characteristics of the TMR sensor, the output voltage U of the first TMR sensor 2 10 See formula (2) for the expression of (2), the output voltage U of the second TMR sensor 3 20 See expression (3), expression U of the output voltage of the third TMR sensor 4 00 Please see formula (4).
U 10 ＝k 1 (T)B 1 V in +b 0 (2)
U 20 ＝-k 2 (T)B 1 V in +b 0 (3)
U 00 ＝k 3 (T)B 0 V in +b 0 (4)
Wherein K is 1 (T) represents the sensitivity of the first TMR sensor, which varies with a variation in temperature T; k (K) 2 (T) represents the sensitivity of the second TMR sensor, which varies with a variation in temperature T; k (K) 3 (T) represents the sensitivity of the third TMR sensor, which varies with a variation in temperature T; b (B) 1 Representing the current I to be measured through the center of the toroidal core 1 P A first magnetic field generated; b (B) 0 Indicating the constant magnetic field in which the third TMR sensor 4 is located; v (V) in Representing the supply voltages of the first TMR sensor 2, the second TMR sensor 3 and the third TMR sensor 4; b 0 The zero bias voltages of the first TMR sensor 2, the second TMR sensor 3, and the third TMR sensor 4 are indicated. Wherein k is 1 (T)＝k 2 (T)＝k 3 (T)。
Differential amplification system5 for outputting the voltage U to the first TMR sensor 2 10 Output voltage U of second TMR sensor 3 20 And the output voltage U of the third TMR sensor 4 00 Differential amplification is carried out to obtain first voltage data U corresponding to the first TMR sensor 2 11 Second voltage data U corresponding to second TMR sensor 3 21 Third voltage data U corresponding to third TMR sensor 4 01 。
As a preferred solution, referring to fig. 1, the differential amplifying system 5 includes: the first differential amplifier 501, the second differential amplifier 502, and the third differential amplifier 503 are specifically as follows:
wherein, the first differential amplifier 501 is connected with the signal output end of the first TMR sensor 2 for outputting the voltage U to the first TMR sensor 2 according to the formula (5) 10 Differential amplification with gain of a first preset value K is carried out to obtain first voltage data U corresponding to the first TMR sensor 2 11 。
U 11 ＝K[k(T)B 1 V in +b 0 ] (5)
A second differential amplifier 502 connected to the signal output terminal of the second TMR sensor 3 for outputting the voltage U to the second TMR sensor 3, see (6) 20 Differential amplification with gain of the first preset value K is carried out to obtain second voltage data U corresponding to the second TMR sensor 3 21 。
U 21 ＝K[k(T)B 1 V in +b 0 ] (6)
A third differential amplifier 503 connected to the signal output terminal of the third TMR sensor 4 for outputting the voltage U to the third TMR sensor 4, see equation (7) 00 Differential amplification with gain of 2K is carried out to obtain third voltage data U corresponding to a third TMR sensor 4 01 。
U 01 ＝2K[k(T)B 0 V in +b 0 ] (7)
A data processing system 6 for processing the first voltage data U according to a preset logic algorithm 11 Second voltageData U 21 And third voltage data U 01 Analyzing and outputting a current I capable of reflecting the current I to be measured P Fourth voltage data U of the magnitude of the current value of (2) out 。
As a preferred embodiment, referring to fig. 1, the data processing system 6 includes: a first subtractor 601, an adder 602, a second subtractor 603, and a divider 604, each of which is specifically as follows:
a first subtractor 601 for applying first voltage data U, see equation (8) 11 And second voltage data U 21 Subtracting to obtain a corresponding first operation result U 12 And the first operation result U 12 To a divider 604.
U 12 ＝U 11 -U 21 ＝K·k(T)B 1 V in (8)
Adder 602 for adding the first voltage data U to equation (9) 11 And second voltage data U 21 Adding to obtain a corresponding second operation result U 22 And the second operation result U 22 To a second subtractor 603.
U 22 ＝U 11 +U 21 ＝2Kb 0 (9)
A second subtractor 603 for applying third voltage data U, see equation (10) 01 And the second operation result U 22 Subtracting to obtain a corresponding third operation result U 02 And the third operation result U 02 To a divider 604.
U 02 ＝U 01 -U 22 ＝2K·k(T)B 0 V in (10)
A divider 604 for dividing the first operation result U by the formula (11) 12 Divided by the third operation result U 02 Obtaining fourth voltage data U out 。
Based on the equation (11), the final output U of the system is known out Does not contain bias voltage b 0 Also independent of temperature T, and only of current I to be measured P The first magnetic field B is generated 1 Proportional to B 0 Is a constant magnetic field generated by the permanent magnet, and is constant. Therefore, the current detection system based on the TMR sensor provided by the embodiment of the invention eliminates the influence of bias voltage and also eliminates the influence of temperature dependence of the sensitivity of the TMR chip.
Referring to fig. 2, a flow chart of a current detection method based on a TMR sensor according to an embodiment of the present invention is shown, and the method includes steps S1 to S3, wherein each step is specifically as follows:
and S1, when the current to be detected passes through the center of the annular iron core with the air gap, detecting a first magnetic field generated by the current to be detected by using a first TMR sensor and a second TMR sensor to obtain the output voltage of the first TMR sensor and the output voltage of the second TMR sensor, and detecting a constant magnetic field by using a third TMR sensor to obtain the output voltage of the third TMR sensor.
The first TMR sensor and the second TMR sensor are arranged in parallel in an air gap of the annular iron core, the magnetic field sensitivity direction of the first TMR sensor is the same as the direction of the first magnetic field, the magnetic field sensitivity direction of the second TMR sensor is opposite to the direction of the first magnetic field, the annular iron core and the air gap of the annular iron core are both in the first magnetic field, and the third TMR sensor is arranged in a constant magnetic field outside the annular iron core.
Preferably, the constant magnetic field is generated by a permanent magnet; wherein both the permanent magnet and the third TMR sensor are placed in the magnetic shield case.
And S2, respectively carrying out differential amplification on the output voltage of the first TMR sensor, the output voltage of the second TMR sensor and the output voltage of the third TMR sensor through a differential amplification system to obtain first voltage data corresponding to the first TMR sensor, second voltage data corresponding to the second TMR sensor and third voltage data corresponding to the third TMR sensor.
Preferably, step S2 includes steps S21 to S23, and each step is specifically as follows:
step S21, differential amplification is carried out on the output voltage of the first TMR sensor to obtain first voltage data corresponding to the first TMR sensor by utilizing a first differential amplifier in a differential amplification system, wherein the gain of the first differential amplifier is a first preset value.
Step S22, differential amplification is carried out on the output voltage of the second TMR sensor to obtain second voltage data corresponding to the second TMR sensor by utilizing a second differential amplifier in the differential amplification system, wherein the gain of the second differential amplifier is a first preset value.
Step S23, utilizing a third differential amplifier in the differential amplification system to perform differential amplification with the gain of the output voltage of the third TMR sensor being a second preset value, and obtaining third voltage data corresponding to the third TMR sensor.
The first preset value is equal to half of the second preset value, the first differential amplifier is connected with the signal output end of the first TMR sensor, the second differential amplifier is connected with the signal output end of the second TMR sensor, and the third differential amplifier is connected with the signal output end of the third TMR sensor.
And S3, analyzing and processing the first voltage data, the second voltage data and the third voltage data according to a preset logic algorithm, and outputting fourth voltage data capable of reflecting the current value of the current to be measured.
Preferably, step S3 includes steps S31 to S32, and each step is specifically as follows:
step S31, subtracting the first voltage data from the second voltage data to obtain a corresponding first operation result, and adding the first voltage data to the second voltage data to obtain a corresponding second operation result.
Step S32, the third voltage data and the second operation result are subtracted to obtain a corresponding third operation result, and the first operation result is divided by the third operation result to obtain fourth voltage data.
It will be clear to those skilled in the art that, for convenience and brevity of description, reference may be made to the corresponding process in the foregoing system embodiment for the specific working process of the above-described method, which is not described in detail herein.
Compared with the prior art, the embodiment of the invention has the following beneficial effects:
the invention provides a current detection system and a method based on a TMR sensor, wherein a first TMR sensor and a second TMR sensor with opposite magnetic field sensitivity directions are arranged in an air gap of an annular iron core, the first TMR sensor and the second TMR sensor are parallel to obtain an output voltage with opposite magnetic field directions and an output voltage with the same magnetic field directions generated by a measured current passing through the center of the annular iron core, a third TMR sensor for measuring a constant magnetic field is additionally arranged to obtain an output voltage corresponding to the constant magnetic field, and then differential amplification and operation processing are carried out on the output voltages of the three TMR sensors through a differential amplification system, so that fourth voltage data capable of reflecting the magnitude of a current value of a current to be measured can be finally output, the influence of the bias voltage of the TMR sensor can be eliminated, the temperature dependence of the TMR sensor is eliminated, the current value of the current to be directly measured based on the fourth voltage data is equivalent to the magnitude of the current value of the current to be measured, the current compensation characteristics of the TMR sensor can be improved under the condition that the temperature characteristics and the bias characteristics of the TMR sensor are not required to be obtained, the current compensation characteristics of the TMR sensor are not required to be improved, and the current compensation circuit is suitable for the current compensation of the current detection system is reduced, and the current compensation system is not complicated.
The foregoing embodiments have been provided for the purpose of illustrating the general principles of the present invention, and are not to be construed as limiting the scope of the invention. It should be noted that any modifications, equivalent substitutions, improvements, etc. made by those skilled in the art without departing from the spirit and principles of the present invention are intended to be included in the scope of the present invention.
Claims (8)
1. A TMR sensor-based current detection system, comprising: a toroidal core with an air gap, a first TMR sensor and a second TMR sensor placed in parallel in the air gap, a third TMR sensor placed in a constant magnetic field outside the toroidal core, a differential amplification system, and a data processing system;
wherein, the annular iron core and the air gap of the annular iron core are both in a first magnetic field; the first magnetic field is generated by current to be measured passing through the center of the annular iron core, the magnetic field sensitivity direction of the first TMR sensor is the same as the direction of the first magnetic field, and the magnetic field sensitivity direction of the second TMR sensor is opposite to the direction of the first magnetic field;
the differential amplification system is used for respectively carrying out differential amplification on the output voltage of the first TMR sensor, the output voltage of the second TMR sensor and the output voltage of the third TMR sensor to obtain first voltage data corresponding to the first TMR sensor, second voltage data corresponding to the second TMR sensor and third voltage data corresponding to the third TMR sensor;
the data processing system is used for analyzing and processing the first voltage data, the second voltage data and the third voltage data according to a preset logic algorithm and outputting fourth voltage data capable of reflecting the current value of the current to be measured.
2. The TMR sensor-based current detection system according to claim 1, wherein the constant magnetic field is generated by a permanent magnet; wherein the permanent magnet and the third TMR sensor are both placed in a magnetic shield case.
3. The TMR sensor-based current detection system of claim 1, wherein said differential amplification system comprises: a first differential amplifier, a second differential amplifier, and a third differential amplifier;
the first differential amplifier is connected with the signal output end of the first TMR sensor and is used for carrying out differential amplification with the gain of the output voltage of the first TMR sensor being a first preset value to obtain first voltage data corresponding to the first TMR sensor;
the second differential amplifier is connected with the signal output end of the second TMR sensor and is used for carrying out differential amplification on the output voltage of the second TMR sensor, wherein the gain of the differential amplification is the first preset value, so as to obtain second voltage data corresponding to the second TMR sensor;
the third differential amplifier is connected with the signal output end of the third TMR sensor and is used for carrying out differential amplification on the output voltage of the third TMR sensor, wherein the gain of the differential amplification is a second preset value, and third voltage data corresponding to the third TMR sensor is obtained;
wherein the first preset value is equal to half of the second preset value.
4. The TMR sensor-based current detection system of claim 1, wherein said data processing system comprises: the system comprises a first subtracter, an adder, a second subtracter and a divider;
the first subtracter is used for subtracting the first voltage data from the second voltage data to obtain a corresponding first operation result, and transmitting the first operation result to the divider;
the adder is configured to add the first voltage data and the second voltage data to obtain a corresponding second operation result, and transmit the second operation result to the second subtractor;
the second subtracter is used for subtracting the third voltage data from the second operation result to obtain a corresponding third operation result, and transmitting the third operation result to the divider;
the divider is configured to divide the first operation result by the third operation result to obtain the fourth voltage data.
5. A TMR sensor-based current detection method, comprising:
when current to be measured passes through the center of an annular iron core with an air gap, a first TMR sensor and a second TMR sensor are respectively utilized to detect a first magnetic field generated by the current to be measured, so as to obtain the output voltage of the first TMR sensor and the output voltage of the second TMR sensor, and a third TMR sensor is utilized to detect a constant magnetic field, so as to obtain the output voltage of the third TMR sensor;
differential amplification is carried out on the output voltage of the first TMR sensor, the output voltage of the second TMR sensor and the output voltage of the third TMR sensor respectively through a differential amplification system, so that first voltage data corresponding to the first TMR sensor, second voltage data corresponding to the second TMR sensor and third voltage data corresponding to the third TMR sensor are obtained;
according to a preset logic algorithm, analyzing the first voltage data, the second voltage data and the third voltage data, and outputting fourth voltage data capable of reflecting the magnitude of the current value of the current to be measured;
the first TMR sensor and the second TMR sensor are arranged in parallel in an air gap of the annular iron core, the magnetic field sensitivity direction of the first TMR sensor is the same as the direction of the first magnetic field, the magnetic field sensitivity direction of the second TMR sensor is opposite to the direction of the first magnetic field, the annular iron core and the air gap of the annular iron core are both in the first magnetic field, and the third TMR sensor is arranged in the constant magnetic field outside the annular iron core.
6. The TMR sensor-based current detection method of claim 5, wherein said constant magnetic field is generated by a permanent magnet; wherein the permanent magnet and the third TMR sensor are both placed in a magnetic shield case.
7. The TMR sensor-based current detection method according to claim 5, wherein the differential amplification system is configured to differentially amplify the output voltage of the first TMR sensor, the output voltage of the second TMR sensor, and the output voltage of the third TMR sensor to obtain first voltage data corresponding to the first TMR sensor, second voltage data corresponding to the second TMR sensor, and third voltage data corresponding to the third TMR sensor, respectively, where the differential amplification system is specifically configured to:
performing differential amplification with the gain of the output voltage of the first TMR sensor being a first preset value by using a first differential amplifier in the differential amplification system to obtain first voltage data corresponding to the first TMR sensor;
performing differential amplification with the gain of the output voltage of the second TMR sensor being the first preset value by using a second differential amplifier in the differential amplification system to obtain second voltage data corresponding to the second TMR sensor;
performing differential amplification with the gain of the output voltage of the third TMR sensor being a second preset value by using a third differential amplifier in the differential amplification system to obtain third voltage data corresponding to the third TMR sensor;
the first preset value is equal to half of the second preset value, the first differential amplifier is connected with the signal output end of the first TMR sensor, the second differential amplifier is connected with the signal output end of the second TMR sensor, and the third differential amplifier is connected with the signal output end of the third TMR sensor.
8. The TMR sensor-based current detection method according to claim 5, wherein the analyzing the first voltage data, the second voltage data and the third voltage data according to a preset logic algorithm, and outputting fourth voltage data capable of reflecting the magnitude of the current value of the current to be detected, specifically includes:
subtracting the first voltage data from the second voltage data to obtain a corresponding first operation result, and adding the first voltage data and the second voltage data to obtain a corresponding second operation result;
and subtracting the third voltage data from the second operation result to obtain a corresponding third operation result, and dividing the first operation result by the third operation result to obtain the fourth voltage data.
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