CN108732404B - Current sensor and multi-flux balance control circuit thereof - Google Patents
Current sensor and multi-flux balance control circuit thereof Download PDFInfo
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- CN108732404B CN108732404B CN201710269957.XA CN201710269957A CN108732404B CN 108732404 B CN108732404 B CN 108732404B CN 201710269957 A CN201710269957 A CN 201710269957A CN 108732404 B CN108732404 B CN 108732404B
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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
- G01R15/18—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using inductive devices, e.g. transformers
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R1/00—Details of instruments or arrangements of the types included in groups G01R5/00 - G01R13/00 and G01R31/00
- G01R1/02—General constructional details
- G01R1/18—Screening arrangements against electric or magnetic fields, e.g. against earth's field
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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
Abstract
The invention discloses a current sensor and a multi-flux balance control circuit thereof.A multi-flux balance control circuit comprising an excitation flux balance module and an alternating current-direct current flux balance module is adopted in the current sensor, the excitation flux balance module generates an excitation compensation magnetic field according to a detected interference magnetic field, and the magnetic flux of a magnetic field formed by mutually superposing the excitation compensation magnetic field and the interference magnetic field, which passes through a plane vertical to a magnetic induction line of the excitation compensation magnetic field and the interference magnetic field, is zero; the AC/DC magnetic flux balance module generates an AC/DC compensation magnetic field according to the detected AC magnetic flux signal and a DC magnetic bias signal output by the excitation module, and the magnetic flux of the magnetic field formed by mutually superposing the AC/DC compensation magnetic field, the DC magnetic bias field and the AC magnetic field passing through a plane perpendicular to a magnetic induction line is zero, so that the magnetic field interference generated by the excitation module is eliminated, the accurate detection of the AC current and the DC current is realized, the current detection precision of the sensor is improved, and the production cost of the sensor is reduced.
Description
Technical Field
The invention relates to the field of current detection, in particular to a current sensor and a multi-flux balance control circuit thereof.
Background
The current sensor can sense the current to be measured, convert large current or micro current into small current and voltage signals which are easy to measure and isolate and output analog signals or digital signals.
The existing magnetic modulation type current sensor generally comprises an excitation module and a direct current magnetic flux balance module. The excitation module is used for generating a target excitation magnetic field so as to detect a direct-current bias magnetic field generated by current to be detected passing through the current sensor and output a direct-current bias magnetic signal corresponding to the direct-current bias magnetic field; the direct current magnetic flux balance module generates a direct current magnetic bias compensation magnetic field according to the direct current magnetic bias signal, compensates the direct current magnetic bias field generated by the current to be detected, and further realizes detection of the direct current.
However, since the whole excitation module is not in a zero magnetic flux state, that is, the excitation module has an interference magnetic field, the interference magnetic field interferes with the dc bias compensation magnetic field generated by the dc magnetic flux balance module, so that the measurement accuracy of the sensor is reduced, and even the sensor cannot work normally. In the prior art, a magnetic shield is added in a sensor to isolate the connection between an excitation module and a direct current magnetic flux balance module, but the magnetic shield is complex in design and expensive, so that the production and assembly of the sensor become very complex, the cost is increased, and the influence caused by unbalanced magnetic flux of the excitation module is not eliminated fundamentally. Meanwhile, the existing current sensor can only detect direct current, and cannot detect alternating current ripple components or alternating current existing in the direct current, so that the detection accuracy of the sensor is reduced, and the current detection of a wider frequency band cannot be realized.
In conclusion, the current sensor has the problems of low current detection precision, complex structure, high cost and incapability of realizing broadband current detection.
Disclosure of Invention
The invention aims to provide a current sensor and a multi-flux balance control circuit thereof, and aims to solve the problems that the current detection precision of the existing current sensor is low, the structure is complex, the cost is high, and the broadband current detection cannot be realized.
The invention is realized in such a way that a multi-flux balance control circuit of a current sensor is connected with an excitation module of the current sensor; the excitation module comprises an excitation oscillator, an excitation unit connected with the excitation oscillator and a direct-current bias detection unit connected with the excitation unit; the excitation oscillator outputs an alternating voltage signal with a preset frequency to the excitation unit so as to excite the excitation unit to generate a target excitation magnetic field, the target excitation magnetic field is used for detecting a direct-current bias magnetic field generated by current to be detected in a circuit to be detected, and the direct-current bias magnetic signal corresponding to the direct-current bias magnetic field is output through the direct-current bias magnetic detection unit; the multi-flux balance control circuit comprises an excitation flux balance module and an alternating current-direct current flux balance module; the alternating current-direct current magnetic flux balance module is connected with the direct current magnetic bias detection unit;
the excitation magnetic flux balance module detects an interference magnetic field generated by the excitation unit, generates an excitation compensation signal according to a detected first detection signal, generates an excitation compensation magnetic field around the excitation module according to the excitation compensation signal, and superposes the excitation compensation magnetic field and the interference magnetic field, wherein the magnetic flux of the superposed first superposed magnetic field passing through a plane perpendicular to a magnetic induction line is zero;
the alternating current-direct current flux balance module detects an alternating current magnetic field generated by the current to be detected and generates an alternating current flux compensation signal according to the detected alternating current flux signal; the alternating current and direct current magnetic flux balance module further generates a direct current magnetic flux compensation signal according to the direct current magnetic flux compensation signal, generates a target alternating current and direct current magnetic flux compensation signal according to the alternating current magnetic flux compensation signal and the direct current magnetic flux compensation signal, generates an alternating current and direct current compensation magnetic field around the circuit to be detected according to the target alternating current and direct current magnetic flux compensation signal, and superposes the alternating current and direct current compensation magnetic field, the direct current bias magnetic field and the alternating current magnetic field, and the magnetic flux of a second superposed magnetic field after superposition, which passes through a plane perpendicular to a magnetic induction line of the second superposed magnetic field, is zero.
The invention also provides a current sensor which comprises an excitation module and the multi-magnetic-flux balance control circuit.
According to the invention, a multi-flux balance control circuit comprising an excitation flux balance module and an AC/DC flux balance module is adopted in a current sensor, the excitation flux balance module is used for detecting an interference magnetic field generated by an excitation unit, an excitation compensation signal is generated according to a detected first detection signal, an excitation compensation magnetic field is generated around the excitation module according to the excitation compensation signal, the excitation compensation magnetic field and the interference magnetic field are mutually superposed, and the magnetic flux of the superposed first superposed magnetic field passing through a plane perpendicular to a magnetic induction line is zero; the alternating current-direct current magnetic flux balancing module detects an alternating current magnetic field generated by current to be detected and generates an alternating current magnetic flux compensation signal according to the detected alternating current magnetic flux signal; the alternating current-direct current magnetic flux balance module generates a direct current magnetic flux compensation signal according to the direct current magnetic flux compensation signal, generates a target alternating current-direct current magnetic flux compensation signal according to the alternating current magnetic flux compensation signal and the direct current magnetic flux compensation signal, generates an alternating current-direct current compensation magnetic field around the circuit to be detected according to the target alternating current-direct current magnetic flux compensation signal, and superposes the alternating current-direct current compensation magnetic field, the direct current bias magnetic field and the alternating current magnetic field.
Drawings
Fig. 1 is a block diagram of a multi-flux balance control circuit of a current sensor according to an embodiment of the present invention;
FIG. 2 is a circuit diagram of a multi-flux balance control circuit of a current sensor according to an embodiment of the present invention;
fig. 3 is a circuit diagram of a multi-flux balance control circuit of a current sensor according to another embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
Fig. 1 is a block diagram of a multi-flux balance control circuit of a current sensor according to an embodiment of the present invention. For convenience of explanation, only the parts related to the embodiments of the present invention are shown, and detailed as follows:
as shown in fig. 1, a multi-flux balance control circuit 1 of a current sensor 100 is connected to an excitation module 2 in the current sensor 100, and is configured to balance an interference magnetic field generated by the excitation module 2 and detect a dc current component and an ac current component in a current Id to be detected in a circuit to be detected.
The Nd is used for indicating a winding corresponding to a lead carrying the current Id to be measured, and when the current Id to be measured flows through the lead, the magnetomotive force generated on the lead is Id multiplied by Wd. Wherein Wd is the number of turns of the winding corresponding to the lead, and is usually 1 turn.
Specifically, the excitation module 2 includes an excitation oscillator 21, an excitation unit 22 connected to the excitation oscillator 21, and a dc bias detection unit 23 connected to the excitation unit 22. The excitation oscillator 21 outputs an alternating voltage signal with a preset frequency to the excitation unit 22 to excite the excitation unit 22 to generate a target excitation magnetic field, the target excitation magnetic field is used for detecting a direct current bias magnetic field generated by a current Id to be detected in a circuit to be detected, and a direct current bias signal corresponding to the direct current bias magnetic field is output through the direct current bias detection unit 22.
In the embodiment of the present invention, the alternating voltage signal may be a square wave signal, a sine wave signal, a triangular wave signal, or the like. Preferably, a square wave voltage signal is selected in the embodiment of the present invention.
In the embodiment of the present invention, the frequency of the alternating voltage signal output by the excitation oscillator 21 may be set according to actual requirements, and is not limited herein.
The excitation unit 22 comprises a first excitation winding N1, a second excitation winding N2, a first excitation iron core T1 and a second excitation iron core T2, the first excitation winding N1 and the second excitation winding N2 are respectively wound around the first excitation iron core T1 and the second excitation iron core T2, and the synonym end of the first excitation winding N1 and the synonym end of the second excitation winding N2 are connected to the output end of the excitation oscillator 21 in common. The excitation oscillator 21 simultaneously outputs alternating voltage signals with preset frequency to the first excitation winding N1 and the second excitation winding N2, and the voltage on the first excitation winding N1 is equal to the voltage signal on the second excitation winding N2 in magnitude and opposite in direction. The first excitation winding N1 and the second excitation winding N2 respectively generate a target excitation magnetic field and a balanced excitation magnetic field under excitation of an alternating voltage signal, theoretically, the target excitation magnetic field and the balanced excitation magnetic field are equal in magnitude and opposite in direction, and the balanced excitation magnetic field and the target excitation magnetic field are superposed to counteract magnetic flux of the target excitation magnetic field in a plane perpendicular to a magnetic induction line of the target excitation magnetic field, so that the outward magnetic flux of the excitation unit 22 is zero. However, in practical applications, since the impedances of the first excitation winding N1 and the second excitation winding N2 may not be completely equal, and the first excitation core T1 and the second excitation core T2 may not be completely the same, the magnitudes of the balanced excitation field generated by the second excitation winding N2 and the target excitation field generated by the first excitation winding N1 may not be completely equal, and then the magnetic flux of the excitation unit 22 to the outside may not be zero, that is, there is an interference magnetic field outside the excitation unit 22. When the field intensity of the target excitation magnetic field is larger than that of the balance excitation magnetic field, the direction of the interference magnetic field is the same as that of the target excitation magnetic field; when the field intensity of the target excitation magnetic field is smaller than the field intensity of the equilibrium excitation magnetic field, the direction of the interference magnetic field is the same as that of the equilibrium excitation magnetic field.
The dc bias detection unit 23 may be a dc bias detection resistor R1, a first end of the dc bias detection resistor R1 is connected to the dotted end of the first excitation winding N1, a second end of the dc bias detection resistor R1 is grounded, and the dc bias detection resistor R1 outputs a dc bias signal through its first end. The first excitation iron core T1 and the second excitation iron core T2 are soft magnetic iron cores, and when the soft magnetic iron cores are brought into a saturated state by outputting an alternating voltage signal of a preset frequency to the first excitation winding N1 through the excitation oscillator 21, the alternating magnetic flux of the soft magnetic iron cores generates higher harmonics. When the current Id to be detected is zero, in one period of the alternating voltage signal, the average voltage on the direct current magnetic biasing detection resistor R1 is zero; when the current Id to be measured is not zero, the first excitation winding N1 detects a dc bias magnetic field generated by the current Id to be measured, so that the average voltage of the dc bias detection resistor R1 is not zero in one cycle of the alternating voltage signal, and the magnitude and direction of the dc bias signal (voltage signal) detected by the dc bias detection resistor R1 reflect the magnitude and direction of the dc bias magnetic field generated by the current Id to be measured, thereby reflecting the magnitude and direction of the current Id to be measured.
The multi-flux balance control circuit 1 comprises an excitation flux balance module 11 and an alternating current-direct current flux balance module 12. The ac/dc magnetic flux balance module 12 is connected to the dc bias detection unit 23.
The excitation flux balance module 12 detects an interference magnetic field generated by the excitation unit 22, generates an excitation compensation signal according to a detected first detection signal (voltage signal), generates an excitation compensation magnetic field around the excitation module 22 according to the excitation compensation signal, superimposes the excitation compensation magnetic field and the interference magnetic field, and makes the magnetic flux of the superimposed first superimposed magnetic field passing through a plane perpendicular to the magnetic induction line of the superimposed first superimposed magnetic field zero, that is, the magnetic flux externally presented by the excitation system formed by the excitation module 2 and the excitation flux balance module 11 is zero. Thus, the magnetic field interference generated by the excitation unit 22 is eliminated, the interference of the external magnetic field to the excitation unit can be prevented, and the detection precision of the current sensor is improved.
The alternating current-direct current flux balance module 12 detects an alternating current magnetic field generated by the current Id to be detected, and generates an alternating current flux compensation signal according to the detected alternating current flux signal; the ac/dc magnetic flux balance module 12 further generates a dc magnetic bias compensation signal according to the dc magnetic bias signal output by the dc magnetic bias detection unit 23, generates a target ac/dc magnetic flux compensation signal according to the ac magnetic flux compensation signal and the dc magnetic bias compensation signal, and generates an ac/dc compensation magnetic field around the circuit to be detected according to the target ac/dc magnetic flux compensation signal, the ac/dc compensation magnetic field, the dc magnetic bias field, and the ac magnetic field are superimposed on each other, and a magnetic flux of a second superimposed magnetic field passing through a plane perpendicular to a magnetic induction line of the second superimposed magnetic field is zero, so that detection of a dc current component and an ac current component in the circuit to be detected Id is realized, current detection accuracy of the sensor is improved, and the sensor realizes broadband current detection.
Specifically, the ac flux balance module 12 superimposes the ac flux compensation signal and the dc bias compensation signal to obtain a target ac/dc flux compensation signal.
Fig. 2 is a circuit diagram of a multi-flux balance control circuit of a current sensor according to an embodiment of the present invention. For convenience of explanation, only the parts related to the embodiments of the present invention are shown, and detailed as follows:
as shown in fig. 2, the excitation flux balance module 11 includes an excitation detection winding N5, a first signal processing unit 110, an excitation compensation winding N3, and an excitation compensation core T3.
The synonym end of the excitation detection winding N5 is grounded, the synonym end of the excitation detection winding N5 is connected with the input end of the first signal processing unit 110, the output end of the first signal processing unit 110 is connected with the synonym end of the excitation compensation winding N3, the synonym end of the excitation compensation winding N3 is grounded, the excitation compensation winding N3 winds the excitation compensation iron core T3, and the excitation detection winding N5 winds the excitation compensation iron core T3 and the excitation iron core in the excitation unit 22 simultaneously. That is, the excitation detecting winding N5 is wound around the excitation compensating core T3, the first excitation core T1 and the second excitation core T2 at the same time.
The excitation detection winding N5 detects the interference magnetic field generated by the excitation unit 22 and outputs a first detection signal; the first signal processing unit 110 processes the first detection signal and outputs an excitation compensation signal; the excitation compensation winding N3 generates an excitation compensation magnetic field under the excitation of the excitation compensation signal, the excitation compensation magnetic field and the interference magnetic field are mutually superposed, and the magnetic flux of the superposed first superposed magnetic field passing through the plane perpendicular to the magnetic induction line is zero. Namely the magnetomotive force I corresponding to the excitation compensation magnetic field generated by the excitation compensation winding N33×W3Magnetomotive force (I) corresponding to the disturbing magnetic field generated by the exciting unit 221×W1+I2×W2) Are equal in size and opposite in direction, i.e. -I3×W3＝I1×W1+I2×W2The excitation system formed by the whole excitation module 2 and the excitation flux balance module 11 presents zero magnetic flux to the outside, so that the magnetic field interference generated by the excitation unit 22 on the excitation detection winding N5 and the alternating current flux balance module 1 is avoided, and the current detection precision of the sensor is improved.
Wherein, I1、I2And I3Currents W on the first excitation winding N1, the second excitation winding N2 and the excitation compensation winding N31、W2And W3The number of turns of the first excitation winding N1, the second excitation winding N2 and the excitation compensation winding N3 are respectively.
The ac/dc flux balance module 12 includes a dc bias signal processing unit 120, an ac flux detecting unit 121, an ac/dc flux compensating unit 122, and a current detecting unit 123.
The input end of the dc bias signal processing unit 120 is connected to the dc bias detection unit 22, the output end of the dc bias signal processing unit 120 is connected to the first input end of the ac/dc magnetic flux compensation unit 122, the output end of the ac magnetic flux detection unit 121 is connected to the second input end of the ac/dc magnetic flux compensation unit 122, and the output end of the ac/dc magnetic flux compensation unit 122 is connected to the current detection unit 123.
The dc magnetic bias signal processing unit 120 processes the dc magnetic bias signal output by the dc magnetic bias detecting unit 22 and outputs a dc magnetic bias compensation signal; the alternating current bias side detection unit 121 detects an alternating current magnetic field generated by the current Id to be detected, and outputs an alternating current flux compensation signal according to the detected alternating current flux signal; the ac/dc flux compensation unit 122 generates a target ac/dc flux compensation signal according to the ac flux compensation signal and the dc bias compensation signal, and generates an ac/dc compensation magnetic field around the circuit to be measured according to the target ac/dc flux compensation signal, where the ac/dc compensation magnetic field, the dc bias magnetic field, and the ac magnetic field are superimposed on each other, and a magnetic flux of a second superimposed magnetic field passing through a plane perpendicular to a magnetic induction line is zero.
Specifically, the ac/dc magnetic flux compensation unit 122 superimposes the ac magnetic flux compensation signal and the dc magnetic bias compensation signal to obtain a target ac/dc magnetic flux compensation signal.
Fig. 3 is a circuit diagram of a multi-flux balance control circuit of a current sensor according to another embodiment of the present invention. For convenience of explanation, only the parts related to the embodiments of the present invention are shown, and detailed as follows:
as an embodiment of the present invention, the first signal processing unit 110 includes a first voltage processing unit 1101 and a first signal amplifying unit 1102, an input terminal of the first voltage processing unit 1101 is an input terminal of the first signal processing unit 110, an output terminal of the first voltage processing unit 1101 is connected to an input terminal of the first signal amplifying unit 1102, and an output terminal of the first signal amplifying unit 1102 is an output terminal of the first signal processing unit 110.
Specifically, the first voltage processing unit 1101 performs processing such as rectification and filtering on a first detection signal detected by the excitation detection winding N5 to obtain a first voltage signal, and the first signal amplifying unit 1102 performs amplification processing on the first voltage signal to obtain an excitation compensation signal.
In practical applications, the first voltage processing unit 1101 may be a rectifying and filtering circuit; the first signal amplifying unit 1102 may be an amplifier, and specifically may be a proportional-integral amplifier, a non-inverting input terminal of the proportional-integral amplifier is an input terminal of the first signal amplifying unit 1102, an inverting input terminal of the proportional-integral amplifier is grounded, and an output terminal of the proportional-integral amplifier is an output terminal of the first signal amplifying unit.
As an embodiment of the present invention, the ac magnetic flux detecting unit 121 includes an ac magnetic flux detecting winding N4, an ac magnetic flux detecting core T4, and an ac magnetic flux signal processing unit 1210.
The different-name end of the alternating-current magnetic flux detection winding N4 is grounded, the same-name end of the alternating-current magnetic flux detection winding N4 is connected with the input end of the alternating-current magnetic flux signal processing unit 1210, the output end of the alternating-current magnetic flux signal processing unit 1210 is the output end of the alternating-current magnetic flux detection unit 121, and the alternating-current magnetic flux detection winding N4 is wound around the alternating-current magnetic flux detection iron core T4.
The alternating current magnetic flux detection winding N4 detects an alternating current magnetic field generated by the current Id to be detected and outputs an alternating current magnetic flux signal; the ac magnetic flux signal processing unit 1210 processes the ac magnetic flux signal and outputs an ac magnetic flux compensation signal.
As an embodiment of the present invention, the ac magnetic flux signal processing unit 1210 includes a second voltage processing unit 1211 and a second signal amplifying unit 1212.
The input end of the second voltage processing unit 1211 is the input end of the alternating-current magnetic flux signal processing unit 1210, the output end of the second voltage processing unit 1211 is connected with the input end of the second signal amplifying unit 1212, and the output end of the second signal amplifying unit 1212 is the output end of the alternating-current magnetic flux signal processing unit 1210.
The second voltage processing unit 1211 performs a process such as rectification filtering on the alternating-current magnetic flux signal detected by the alternating-current magnetic flux detection winding N4 and outputs a second voltage signal, and the second signal amplifying unit 1212 performs an amplification process on the second voltage signal and outputs an alternating-current magnetic flux compensation signal to the alternating-current magnetic flux compensation unit 122.
In practical applications, the second voltage processing unit 1211 may be a rectifying and filtering circuit, and the second signal amplifying unit 1212 may be an amplifier, and specifically, may be a proportional-integral amplifier.
As an embodiment of the present invention, the dc bias signal processing unit 120 includes a third voltage processing unit 1201 and a third signal amplifying unit 1202.
The input end of the third voltage processing unit 1201 is the input end of the dc magnetic bias signal processing unit 120, the output end of the third voltage processing unit 1201 is connected to the input end of the third signal amplifying unit 1202, and the output end of the third signal amplifying unit 1202 is the output end of the dc magnetic bias signal processing unit 120.
The third voltage processing unit 1201 performs rectification filtering and the like on the dc magnetic bias signal output by the dc magnetic bias detecting unit 22 and outputs a third voltage signal, and the third signal amplifying unit 1202 performs amplification processing on the third voltage signal and outputs a dc magnetic bias compensation signal to the ac magnetic flux compensation unit 122.
In practical applications, the third voltage processing unit 1201 may be a rectifying and filtering circuit, and the third signal amplifying unit 1202 may be an amplifier, and specifically, may be a proportional-integral amplifier.
As an embodiment of the present invention, the current detection unit 123 is a current detection resistor RL; a first end of the current detection resistor RL is connected to the output end of the ac/dc magnetic flux compensation unit 122, and a second end of the current detection resistor RL is grounded.
As an embodiment of the present invention, the ac/dc flux compensation unit 122 includes a power amplification unit 1221 and a proportional compensation winding N6.
The first input end and the second input end of the power amplification unit 1221 are respectively the first input end and the second input end of the ac/dc magnetic flux compensation unit 122, the output end of the power amplification unit 1221 is connected with the same-name end of the proportional compensation winding N6, and the different-name end of the proportional compensation winding N6 is the output end of the ac/dc magnetic flux compensation unit 122. The proportional compensation winding N6 is wound around the first excitation winding N1, the second excitation winding N2, the excitation compensation winding N3 and the alternating current flux detection winding N4 at the same time.
The power amplifier 1221 inputs the received ac magnetic flux compensation signal and dc magnetic bias compensation signalPerforming line superposition and generating a target alternating current-direct current magnetic flux compensation signal; the proportional compensation winding N6 generates an alternating current and direct current compensation magnetic field under the excitation of the target alternating current and direct current magnetic flux compensation signal, the alternating current and direct current compensation magnetic field, the direct current bias magnetic field and the alternating current magnetic field are mutually superposed, and the magnetic flux of the superposed second superposed magnetic field passing through a plane perpendicular to the magnetic induction line is zero. I.e. the magnetomotive force I generated on the proportional compensation winding N6 by the current I6 flowing through the proportional compensation winding N66×W6The magnetomotive force Id multiplied by Wd generated on the winding Nd corresponding to the lead by the current Id to be measured flowing through the lead is equal in size and opposite in direction, namely-I6×W6Id × Wd. Wherein, W6And Wd are the number of turns of proportional compensating winding N6 and the winding Nd for the wire, respectively. Because the number of turns of the winding Nd corresponding to the lead wire is 1, the proportional compensation winding N6 is known, and the current I6 flowing through the proportional compensation winding N6 can be obtained by measuring the voltage at two ends of the current detection resistor RL, so that the formula-I can be further obtained according to6×W6And the size of the current to be measured Id is obtained by calculating Id multiplied by Wd, so that the high-precision detection of the current to be measured is realized.
In practical applications, the power amplification unit 1221 may be a power amplifier, and the non-inverting input terminal and the inverting input terminal of the power amplifier are the first input terminal and the second input terminal of the power amplification unit 1221, respectively.
Specifically, in the embodiment of the present invention, the dc bias detection unit 23, the third voltage processing unit 1201, the third signal amplification unit 1202, the power amplification unit 1221, and the proportional compensation winding N6 form a dc bias compensation circuit, which is used to compensate a dc bias magnetic field generated by a dc current in the current Id to be detected, so as to detect a dc current component in the current Id to be detected. The ac magnetic flux detection winding N4, the second voltage processing unit 1211, the second signal amplifying unit 1212, the power amplifying unit 1221, and the proportional compensation winding N6 form an ac magnetic flux compensation circuit, which is used to compensate an ac magnetic field generated by the ac current in the current Id to be measured, thereby detecting the ac component in the current Id to be measured.
When the current Id is not zero, the dc bias detection unit 23 performs a first excitation windingThe direct-current bias magnetic field detected by the N1 outputs a direct-current bias magnetic signal, the third voltage processing unit 1201 processes the direct-current bias magnetic signal and outputs a third voltage signal, the third signal amplifying unit 1202 amplifies the third voltage signal and outputs a direct-current bias magnetic compensation signal to the power amplifying unit 1221, and the power amplifying unit 1221 outputs a target compensation current I6 according to the direct-current bias magnetic compensation signal, so that the magnetomotive force I6 generated by the current I6 flowing through the proportional compensation winding N6 on the proportional compensation winding N66×W6The magnetomotive force Id multiplied by Wd generated on the winding Nd corresponding to the lead by the current Id to be measured flowing through the lead is completely balanced. The larger the current Id to be measured is, the larger the target compensation current I6 output by the power amplification unit 1221 is, and the smaller the current Id to be measured is, the smaller the target compensation current I6 output by the power amplification unit 1221 is. In fact, since the gain of the power amplifying unit 1221 is limited and there is a zero point shift, the current I6 flowing through the proportional compensating winding N6 generates a magnetomotive force I on the proportional compensating winding N66×W6The magnetomotive force Id multiplied by Wd generated on the winding Nd corresponding to the lead by the current Id to be measured flowing through the lead cannot be completely balanced, a negative feedback system needs to be formed in order to maintain the balance between the magnetomotive force Id multiplied by Wd, the alternating current flux compensation circuit can achieve the purpose, as long as the magnetomotive force on the proportional compensation winding N6 and the magnetomotive force on the lead winding Nd are unbalanced, a detection voltage is formed on the alternating current flux detection winding N4, the detection voltage is input into the power amplification unit 1221 after being processed by the second signal processing unit 1210, and therefore the target compensation current I6 output by the power amplification unit 1221 is changed, and further the magnetomotive force I6 generated on the proportional compensation winding N6 by the current I6 is changed6×W6The magnetomotive force Id multiplied by Wd generated on the winding Nd corresponding to the lead by the current Id to be measured flowing through the lead reaches a balanced state. Magnetomotive force I generated on proportional compensation winding N6 when current I6 is applied6×W6After the magnetomotive force Id multiplied by Wd generated on the winding Nd corresponding to the lead by the current Id to be detected flowing through the lead reaches the balanced state, the alternating current magnetic flux signal detected on the alternating current magnetic flux detection winding N4 and the direct current magnetic bias signal detected by the direct current magnetic bias detection resistor R1 are both zero, so that the sensor realizes zero magnetism outwardsThe method is simple.
The embodiment of the present invention further provides a current sensor 100, which includes an excitation module 2, and further includes the multi-flux balance control circuit 1 in the above embodiment.
It should be noted that the structure and the operation principle of the multi-flux balance control circuit 1 included in the current sensor 100 in this embodiment are completely the same as those of the multi-flux balance control circuit 1 in the above embodiment, and the operation principle of the current sensor 100 in this embodiment may specifically refer to the description in the above embodiment, and is not repeated herein.
According to the embodiment of the invention, a multi-flux balance control circuit comprising an excitation flux balance module and an alternating current-direct current flux balance module is adopted in a current sensor, the excitation flux balance module is used for detecting an interference magnetic field generated by an excitation unit, an excitation compensation signal is generated according to a detected first detection signal, an excitation compensation magnetic field is generated around the excitation module according to the excitation compensation signal, the excitation compensation magnetic field and the interference magnetic field are mutually superposed, and the magnetic flux of the superposed first superposed magnetic field passing through a plane perpendicular to a magnetic induction line is zero; the alternating current-direct current magnetic flux balancing module detects an alternating current magnetic field generated by current to be detected and generates an alternating current magnetic flux compensation signal according to the detected alternating current magnetic flux signal; the alternating current-direct current magnetic flux balance module generates a direct current magnetic flux compensation signal according to the direct current magnetic flux compensation signal, generates a target alternating current-direct current magnetic flux compensation signal according to the alternating current magnetic flux compensation signal and the direct current magnetic flux compensation signal, generates an alternating current-direct current compensation magnetic field around the circuit to be detected according to the target alternating current-direct current magnetic flux compensation signal, and superposes the alternating current-direct current compensation magnetic field, the direct current bias magnetic field and the alternating current magnetic field.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.
Claims (10)
1. A multi-flux balance control circuit of a current sensor is connected with an excitation module of the current sensor; the excitation module comprises an excitation oscillator, an excitation unit connected with the excitation oscillator and a direct-current bias detection unit connected with the excitation unit; the excitation oscillator outputs an alternating voltage signal with a preset frequency to the excitation unit so as to excite the excitation unit to generate a target excitation magnetic field, the target excitation magnetic field is used for detecting a direct-current bias magnetic field generated by current to be detected in a circuit to be detected, and the direct-current bias magnetic signal corresponding to the direct-current bias magnetic field is output through the direct-current bias magnetic detection unit; the multi-flux balance control circuit is characterized by comprising an excitation flux balance module and an alternating current-direct current flux balance module; the alternating current-direct current magnetic flux balance module is connected with the direct current magnetic bias detection unit;
the excitation magnetic flux balance module detects an interference magnetic field generated by the excitation unit, generates an excitation compensation signal according to a detected first detection signal, generates an excitation compensation magnetic field around the excitation module according to the excitation compensation signal, and superposes the excitation compensation magnetic field and the interference magnetic field, wherein the magnetic flux of the superposed first superposed magnetic field passing through a plane vertical to a magnetic induction line of the first superposed magnetic field is zero;
the alternating current-direct current flux balance module detects an alternating current magnetic field generated by the current to be detected and generates an alternating current flux compensation signal according to the detected alternating current flux signal; the alternating current-direct current magnetic flux balancing module further generates a direct current magnetic bias compensation signal according to the direct current magnetic bias signal, generates a target alternating current-direct current magnetic field compensation signal according to the alternating current magnetic flux compensation signal and the direct current magnetic bias compensation signal, generates an alternating current-direct current compensation magnetic field around the circuit to be tested according to the target alternating current-direct current magnetic field compensation signal, and superposes the alternating current-direct current compensation magnetic field, the direct current magnetic bias field and the alternating current magnetic field, and the magnetic flux of a superposed second superposed magnetic field passing through a plane perpendicular to a magnetic induction line of the second superposed magnetic field is zero.
2. The multi-flux balance control circuit of a current sensor according to claim 1, wherein the excitation flux balance module includes an excitation detection winding, a first signal processing unit, an excitation compensation winding, and an excitation compensation core;
the different name end of the excitation detection winding is grounded, the same name end of the excitation detection winding is connected with the input end of the first signal processing unit, the output end of the first signal processing unit is connected with the same name end of the excitation compensation winding, the different name end of the excitation compensation winding is grounded, the excitation compensation winding is wound on the excitation compensation iron core, and the excitation detection winding is simultaneously wound on the excitation compensation iron core and the excitation iron core in the excitation unit;
the excitation detection winding detects an interference magnetic field generated by the excitation unit and outputs a first detection signal; the first signal processing unit processes the first detection signal and outputs an excitation compensation signal; the excitation compensation winding generates an excitation compensation magnetic field under the excitation of the excitation compensation signal, the excitation compensation magnetic field and the interference magnetic field are mutually superposed, and the magnetic flux of the superposed first superposed magnetic field passing through a plane perpendicular to the magnetic induction line of the first superposed magnetic field is zero.
3. The multi-flux balance control circuit of a current sensor according to claim 2, wherein the first signal processing unit comprises a first voltage processing unit and a first signal amplifying unit, an input terminal of the first voltage processing unit is an input terminal of the first signal processing unit, an output terminal of the first voltage processing unit is connected to an input terminal of the first signal amplifying unit, and an output terminal of the first signal amplifying unit is an output terminal of the first signal processing unit.
4. The multi-flux balance control circuit of a current sensor according to claim 1, wherein the ac/dc flux balance module comprises a dc bias signal processing unit, an ac flux detection unit, an ac/dc flux compensation unit, and a current detection unit;
the input end of the direct current magnetic bias signal processing unit is connected with the direct current magnetic bias detection unit, the output end of the direct current magnetic bias signal processing unit is connected with the first input end of the alternating current and direct current magnetic flux compensation unit, the output end of the alternating current magnetic flux detection unit is connected with the second input end of the alternating current and direct current magnetic flux compensation unit, and the output end of the alternating current and direct current magnetic flux compensation unit is connected with the current detection unit;
the direct current magnetic bias signal processing unit processes the direct current magnetic bias signal output by the direct current magnetic bias detection unit and outputs a direct current magnetic bias compensation signal; the alternating current magnetic flux detection unit detects an alternating current magnetic field generated by the current to be detected and outputs an alternating current magnetic flux compensation signal according to the detected alternating current magnetic flux signal; the alternating current and direct current magnetic flux compensation unit generates a target alternating current and direct current magnetic flux compensation signal according to the alternating current magnetic flux compensation signal and the direct current magnetic bias compensation signal, an alternating current and direct current compensation magnetic field is generated around the circuit to be tested according to the target alternating current and direct current magnetic flux compensation signal, the alternating current and direct current compensation magnetic field, the direct current bias magnetic field and the alternating current magnetic field are mutually superposed, and the magnetic flux of a second superposed magnetic field after superposition, which passes through a plane perpendicular to a magnetic induction line of the second superposed magnetic field, is zero.
5. The multi-flux balance control circuit of a current sensor according to claim 4, wherein the ac magnetic flux detecting unit includes an ac magnetic flux detecting winding, an ac magnetic flux detecting core, and an ac magnetic flux signal processing unit;
the different name end of the alternating current magnetic flux detection winding is grounded, the same name end of the alternating current magnetic flux detection winding is connected with the input end of the alternating current magnetic flux signal processing unit, the output end of the alternating current magnetic flux signal processing unit is the output end of the alternating current magnetic flux detection unit, and the alternating current magnetic flux detection winding is wound on the alternating current magnetic flux detection iron core;
the alternating current magnetic flux detection winding detects an alternating current magnetic field generated by the current to be detected and outputs an alternating current magnetic flux signal; the alternating current magnetic flux signal processing unit processes the alternating current magnetic flux signal and outputs an alternating current magnetic flux compensation signal.
6. The multi-flux balance control circuit of a current sensor according to claim 5, wherein the alternating-current flux signal processing unit includes a second voltage processing unit and a second signal amplifying unit;
the input end of the second voltage processing unit is the input end of the alternating current magnetic flux signal processing unit, the output end of the second voltage processing unit is connected with the input end of the second signal amplifying unit, and the output end of the second signal amplifying unit is the output end of the alternating current magnetic flux signal processing unit.
7. The multi-flux balance control circuit of a current sensor according to claim 4, wherein the dc bias signal processing unit includes a third voltage processing unit and a third signal amplifying unit;
the input end of the third voltage processing unit is the input end of the direct current magnetic bias signal processing unit, the output end of the third voltage processing unit is connected with the input end of the third signal amplifying unit, and the output end of the third signal amplifying unit is the output end of the direct current magnetic bias signal processing unit.
8. The multi-flux balance control circuit of a current sensor according to claim 4, wherein the ac/dc flux compensation unit comprises a power amplification unit and a proportional compensation winding;
the first input end and the second input end of the power amplification unit are respectively the first input end and the second input end of the alternating current and direct current magnetic flux compensation unit, the output end of the power amplification unit is connected with the homonymous end of the proportional compensation winding, and the synonym end of the proportional compensation winding is the output end of the alternating current and direct current magnetic flux compensation unit;
the power amplification unit superposes the received alternating current magnetic flux compensation signal and the direct current magnetic bias compensation signal and generates a target alternating current and direct current magnetic flux compensation signal; the proportional compensation winding generates an alternating current and direct current compensation magnetic field under the excitation of the target alternating current and direct current magnetic flux compensation signal, the alternating current and direct current compensation magnetic field, the direct current bias magnetic field and the alternating current magnetic field are mutually superposed, and the magnetic flux of a second superposed magnetic field after superposition, which passes through a plane perpendicular to a magnetic induction line of the second superposed magnetic field, is zero.
9. The multi-flux balance control circuit of a current sensor according to claim 4, wherein the current detection unit is a current detection resistor; the first end of the current detection resistor is connected with the output end of the alternating current-direct current magnetic flux compensation unit, and the second end of the current detection resistor is grounded.
10. A current sensor comprising an excitation module, characterized in that it further comprises a multi-flux balance control circuit according to any one of claims 1 to 9.
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| CN108169538A (en) * | 2018-03-19 | 2018-06-15 | 深圳市航智精密电子有限公司 | More closed control circuits of fluxgate current sensor |
| CN111693753A (en) * | 2019-11-29 | 2020-09-22 | 中国计量大学 | Novel direct current measuring device |
| CN112230043B (en) * | 2020-10-10 | 2023-12-08 | 浙江巨磁智能技术有限公司 | Method for separating alternating current from direct current by utilizing magnetic balance principle |
| CN113049868A (en) * | 2021-03-10 | 2021-06-29 | 优利德科技(中国)股份有限公司 | Alternating current and direct current measuring device and measuring method |
| CN113625195A (en) * | 2021-06-18 | 2021-11-09 | 国网浙江省电力有限公司杭州供电公司 | Distributed direct-current magnetic bias monitoring control center system for transformer winding |
| CN115941823B (en) * | 2021-08-25 | 2023-12-12 | 荣耀终端有限公司 | Anti-interference module and terminal equipment |
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