CN114280350A - Large current measuring method based on high-precision current sensor and shunt - Google Patents
Large current measuring method based on high-precision current sensor and shunt Download PDFInfo
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- CN114280350A CN114280350A CN202111534707.7A CN202111534707A CN114280350A CN 114280350 A CN114280350 A CN 114280350A CN 202111534707 A CN202111534707 A CN 202111534707A CN 114280350 A CN114280350 A CN 114280350A
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Abstract
The invention discloses a high-current measuring method based on a high-precision current sensor and a shunt, which is used for accurately measuring high current and comprises the following steps of S1: a large current is passed through the shunt so that the total current is split into a relatively large first current and a relatively small second current and a high precision current sensor is set to the second current to measure the relatively small current. The invention discloses a high-current measuring method based on a high-precision current sensor and a shunt, which is used for shunting current input by the shunt so that the high-precision current sensor can accurately measure the current on the low-current side of the shunt, and then the shunt is used for calculating the actually input high current at a constant shunt ratio.
Description
Technical Field
The invention belongs to the technical field of current sensors, and particularly relates to a high-current measuring method based on a high-precision current sensor and a current divider.
Background
The current sensor is a detection device which can sense the information of the current to be detected and convert the sensed information into an electric signal meeting certain standards or other information in required forms according to a certain rule for output so as to meet the requirements of information transmission, processing, storage, display, recording, control and the like.
However, the existing current sensor has low measuring range and low precision, especially the detection precision for large current.
Therefore, the above problems are further improved.
Disclosure of Invention
The invention mainly aims to provide a high-current measuring method based on a high-precision current sensor and a shunt, which is used for shunting current input by the shunt so that the high-precision current sensor can accurately measure the current on the low-current side of the shunt and then calculate the actually input high current through the shunt at a constant shunt ratio.
The invention also aims to provide a high-current measuring device based on the high-precision current sensor and the shunt, which has the advantages of high precision, convenience in use, stable structure and the like.
In order to achieve the above object, the present invention provides a high current measuring method based on a high precision current sensor and a shunt, which is used for accurately measuring a high current, and comprises the following steps:
step S1: passing a large current through the shunt such that the total current is divided into a relatively large first current and a relatively small second current and setting a high precision current sensor to the second current to measure the relatively small current;
step S2: the double detection coil of the high-precision current sensor comprises a winding N1 and a winding N2 which are respectively arranged on a magnetic core T1 and a magnetic core T2, and the modulated triangular wave is simultaneously excited on the winding N1 and the winding N2, so that magnetizing current is generated;
step S3: the wire of the second current passes through the winding N1 and the winding N2 respectively to form a virtual primary coil N on one side of the shuntPMeasured current I corresponding to primary coilP；
Step S4: when flowing through the primary coil NPMeasured current IPWhen the change occurs, the magnetic flux of the core T1 and the magnetic flux of the core T2, which are respectively provided with the winding N1 and the winding N2, are changed, so that the magnetic flux of one of the core T1 and the core T2 is increased and the magnetic flux of the other core is decreased, and further, the magnetizing currents corresponding to the core T1 and the core T2 are changed and are respectively input to the zero-flux detector U1, which is respectively provided with the winding N1 and the winding N2, which are respectively provided with the core T1 and the core T2;
step S5: the zero magnetic flux detector U1 obtains a current difference signal value according to the input magnetizing currents corresponding to the magnetic core T1 and the magnetic core T2 and outputs the current difference signal value to the operational amplifier Z, the operational amplifier Z transmits the generated compensation current to the compensation coil N3 after feedback amplification processing, and the compensation coil N3 is used as a common winding of the magnetic core N1 and the magnetic core N2, so that magnetic fluxes with equal magnitude and opposite directions are generated on the magnetic core N1 and the magnetic core N2 to offset the measured current IPThe induced magnetic flux changes, so that the magnetic fluxes of the magnetic core N1 and the magnetic core N2 are balanced, and the measured current I is further detectedPIs equal to the value of the compensation current by which the exact value of the second current is obtained, and finally by the constant splitting ratio of the splitter the exact value of the large current comprising the first current and the second current is obtained.
As a further preferable technical solution of the above technical solution, in step S5, the ampler Z performs first feedback and second feedback on the compensation current through a first feedback device and a second feedback device, respectively, where:
the first feedback device comprises a resistor R1 and a capacitor C1, the negative input end of the operational amplifier Z is connected to a feedback coil N4 through a resistor R1 and the capacitor C1 in sequence, and the feedback coil N4 serves as a common winding of a magnetic core T1 and a magnetic core T2;
the second feedback device comprises a resistor R2 and a capacitor C3, a resistor R2 and a capacitor C3 are connected between the negative input end and the output end of the operational amplifier Z, the output end of the operational amplifier Z is electrically connected with the input end of the compensation coil N3, and the output end of the compensation coil N3 is grounded through a sampling resistor R3.
As a further preferable technical solution of the above technical solution, in step S5, the accurate value of the second current is obtained by collecting the current of the sampling resistor R3.
As a more preferable embodiment of the above-described embodiment, the zero-flux detector detects a dc current signal flowing through the shunt, and the feedback coil N4 detects an ac current signal flowing through the shunt.
As a further preferable technical solution of the above technical solution, the magnetic core T1 and the magnetic core T2 are symmetrically arranged, and the windings N1 and N2 have the same number of turns and opposite winding directions.
Drawings
Fig. 1 is a schematic diagram of a high-current measuring method based on a high-precision current sensor and a shunt.
The reference numerals include: 10. a flow divider; 11. a first wiring screw hole; 12. a second wiring screw hole; 13. a connecting member; 20. high accuracy current sensor.
Detailed Description
The following description is presented to disclose the invention so as to enable any person skilled in the art to practice the invention. The preferred embodiments in the following description are given by way of example only, and other obvious variations will occur to those skilled in the art. The basic principles of the invention, as defined in the following description, may be applied to other embodiments, variations, modifications, equivalents, and other technical solutions without departing from the spirit and scope of the invention.
With reference to figure 1 of the drawings,
in the preferred embodiment of the present invention, it should be noted by those skilled in the art that the screw holes and the like according to the present invention can be regarded as the prior art.
Preferred embodiments.
The invention discloses a high-current measuring method based on a high-precision current sensor and a shunt, which is used for accurately measuring high current and comprises the following steps:
step S1: a large current is passed through the shunt 10 so that the total current is divided into a relatively large first current and a relatively small second current and a high-precision current sensor is set to the second current to measure the relatively small current;
step S2: the double detection coil of the high-precision current sensor 20 includes a winding N1 and a winding N2 provided to the core T1 and the core T2, respectively, and excites the modulated triangular wave to the winding N1 and the winding N2 at the same time, thereby generating a magnetizing current;
step S3: the wire of the second current passes through the winding N1 and the winding N2 respectively to form a virtual primary coil N on one side of the shuntPMeasured current I corresponding to primary coilP；
Step S4: when flowing through the primary coil NPMeasured current IPWhen the change occurs, the magnetic flux of the core T1 and the magnetic flux of the core T2, which are respectively provided with the winding N1 and the winding N2, are changed, so that the magnetic flux of one of the core T1 and the core T2 is increased and the magnetic flux of the other core is decreased, and further, the magnetizing currents corresponding to the core T1 and the core T2 are changed and are respectively input to the zero-flux detector U1, which is respectively provided with the winding N1 and the winding N2, which are respectively provided with the core T1 and the core T2;
step S5: the zero magnetic flux detector U1 obtains a current difference signal value according to the input magnetizing currents corresponding to the magnetic core T1 and the magnetic core T2 and outputs the current difference signal value to the operational amplifier Z, the operational amplifier Z transmits the generated compensation current to the compensation coil N3 after feedback amplification processing, and the compensation coil N3 is used as a common winding of the magnetic core N1 and the magnetic core N2, so that magnetic fluxes with equal magnitude and opposite directions are generated on the magnetic core N1 and the magnetic core N2 to offset the measured current IPThe induced magnetic flux changes, so that the magnetic fluxes of the magnetic core N1 and the magnetic core N2 are balanced, and the measured current I is further detectedPIs equal to the value of the compensation current by which the exact value of the second current is obtained, and finally by the constant splitting ratio of the splitter the exact value of the large current comprising the first current and the second current is obtained.
Specifically, in step S5, the ampler Z performs first feedback and second feedback on the compensation current through a first feedback device and a second feedback device, respectively, where:
the first feedback device comprises a resistor R1 and a capacitor C1, the negative input end of the operational amplifier Z is connected to a feedback coil N4 through a resistor R1 and the capacitor C1 in sequence, and the feedback coil N4 serves as a common winding of a magnetic core T1 and a magnetic core T2;
the second feedback device comprises a resistor R2 and a capacitor C3, a resistor R2 and a capacitor C3 are connected between the negative input end and the output end of the operational amplifier Z, the output end of the operational amplifier Z is electrically connected with the input end of the compensation coil N3, and the output end of the compensation coil N3 is grounded through a sampling resistor R3.
More specifically, in step S5, an accurate value of the second current is obtained by sampling the current of the sampling resistor R3.
Further, a zero flux detector is used to detect a dc current signal flowing through the shunt, and a feedback coil N4 is used to detect an ac current signal flowing through the shunt.
Further, core T1 and core T2 are symmetrically disposed, and winding N1 and winding N2 have the same number of turns and opposite winding directions.
Preferably, the shunt 10 includes a first wiring screw hole 11, a connection member 13, and a second wiring screw hole 12, and the first wiring screw hole 11 and the second wiring screw hole 12 are located at both sides of the connection member 13.
The invention mainly comprises a high-precision current sensor and a current divider, wherein the high-precision current sensor comprises a probe, a zero magnetic flux detector, an amplifying circuit and an output circuit. The probe comprises three magnetic cores and four winding coils, wherein T1 and T2 are magnetic cores with the same magnetic quantity and materials, T3 is a common inductance magnetic core, N1 and N2 are windings of T1 and T2 respectively, N3 and N4 are windings common to T1 and T2, N4 is a feedback coil, N4 is a compensation coil, and a measured current Ip is connected with all the magnetic cores through a primary coil Np (virtual coil) and is connected as shown in figure 1. The zero flux detector is used to detect the dc current signal, which is directly induced by the feedback coil N4. The shunt mainly comprises a low-resistance constant-shunt-ratio copper material (connecting piece) and a wiring screw hole.
As shown in FIG. 1, the double detection coils are respectively arranged on two symmetrical magnetic cores made of the same material, the number of turns is equal, the winding directions are opposite, and the modulation triangular wave of kHz magnitude simultaneously excites the two detection coils to generate magnetizing current. The wire of the current to be measured passes through the two detection magnetic cores to form a primary coil, when the current flowing through the primary coil changes, magnetic flux changes are generated on the two detection magnetic cores, so that the magnetic flux of one of the two detection magnetic cores is increased, the magnetic flux of the other of the two detection magnetic cores is reduced, according to the nonlinear characteristic of the magnetic core material, the signal difference of the magnetizing currents of the two coils changes along with the change of the current to be measured flowing through the primary coil, and accordingly, the zero magnetic flux detector is designed to detect the signal difference of the two magnetizing currents, the value is amplified through feedback to generate a compensation current to flow through the compensation coil, and the compensation coil is wound on the two detection magnetic cores, so that magnetic fluxes with equal magnitude and opposite directions are generated on the two magnetic cores to counteract the magnetic flux change caused by the primary current. Therefore, the magnetic fluxes in the two magnetic cores can be balanced, the number of turns of the current to be measured is equal to that of the compensating current, and the compensating current value is measured through the output resistance value, namely the current value on the low current side of the shunt is obtained.
The invention has the advantages that:
1. the measuring range is large (alternating current and direct current);
2. the precision is high, the linearity is high, the compensation effect is obvious, the anti-interference capability is strong, and the reliability is high;
3. measuring large current by a method for measuring small current;
4. the cost is low.
It should be noted that the technical features such as screw holes and the like related to the present patent application should be regarded as the prior art, and the specific structure, the operation principle, the control mode and the spatial arrangement mode of the technical features may be selected conventionally in the field, and should not be regarded as the invention point of the present patent, and the present patent is not further specifically described in detail.
It will be apparent to those skilled in the art that modifications and equivalents may be made in the embodiments and/or portions thereof without departing from the spirit and scope of the present invention.
Claims (5)
1. A high-current measuring method based on high-precision current sensor and shunt is used for accurately measuring high current, and is characterized by comprising the following steps:
step S1: passing a large current through the shunt such that the total current is divided into a relatively large first current and a relatively small second current and setting a high precision current sensor to the second current to measure the relatively small current;
step S2: the double detection coil of the high-precision current sensor comprises a winding N1 and a winding N2 which are respectively arranged on a magnetic core T1 and a magnetic core T2, and the modulated triangular wave is simultaneously excited on the winding N1 and the winding N2, so that magnetizing current is generated;
step S3: the wire of the second current passes through the winding N1 and the winding N2 respectively to form a virtual primary coil N on one side of the shuntPMeasured current I corresponding to primary coilP；
Step S4: when flowing through the primary coil NPMeasured current IPWhen the change occurs, the magnetic flux of the core T1 and the magnetic flux of the core T2, which are respectively provided with the winding N1 and the winding N2, are changed, so that the magnetic flux of one of the core T1 and the core T2 is increased and the magnetic flux of the other core is decreased, and further, the magnetizing currents corresponding to the core T1 and the core T2 are changed and are respectively input to the zero-flux detector U1, which is respectively provided with the winding N1 and the winding N2, which are respectively provided with the core T1 and the core T2;
step S5: the zero magnetic flux detector U1 obtains a current difference signal value according to the input magnetizing currents corresponding to the magnetic core T1 and the magnetic core T2 and outputs the current difference signal value to the operational amplifier Z, the operational amplifier Z transmits the generated compensation current to the compensation coil N3 after feedback amplification processing, and the compensation coil N3 is used as a common winding of the magnetic core N1 and the magnetic core N2, so that magnetic fluxes with equal magnitude and opposite directions are generated on the magnetic core N1 and the magnetic core N2 to offset the measured current IPThe induced magnetic flux changes, so that the magnetic fluxes of the magnetic core N1 and the magnetic core N2 are balanced, and the measured current I is further detectedPIs equal to the value of the compensation current by which the exact value of the second current is obtained, and finally by the constant splitting ratio of the splitter the exact value of the large current comprising the first current and the second current is obtained.
2. The high-precision current sensor and shunt-based large current measuring method according to claim 1, wherein in step S5, the operational amplifier Z performs first feedback and second feedback on the compensation current through a first feedback device and a second feedback device, respectively, wherein:
the first feedback device comprises a resistor R1 and a capacitor C1, the negative input end of the operational amplifier Z is connected to a feedback coil N4 through a resistor R1 and the capacitor C1 in sequence, and the feedback coil N4 serves as a common winding of a magnetic core T1 and a magnetic core T2;
the second feedback device comprises a resistor R2 and a capacitor C3, a resistor R2 and a capacitor C3 are connected between the negative input end and the output end of the operational amplifier Z, the output end of the operational amplifier Z is electrically connected with the input end of the compensation coil N3, and the output end of the compensation coil N3 is grounded through a sampling resistor R3.
3. The high-precision current sensor and shunt-based large current measuring method as claimed in claim 2, wherein in step S5, the current of the sampling resistor R3 is collected to obtain the precise value of the second current.
4. A high current measuring method based on high precision current sensor and shunt according to claim 3, wherein the zero flux detector is used to detect the DC current signal flowing through the shunt, and the feedback coil N4 is used to detect the AC current signal flowing through the shunt.
5. A high-current measuring method based on high-precision current sensor and shunt combination as claimed in claim 4, wherein magnetic core T1 and magnetic core T2 are symmetrically arranged, winding N1 and winding N2 have the same number of turns and opposite winding directions.
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| CN111398650A (en) * | 2020-06-04 | 2020-07-10 | 华中科技大学 | Quick response direct current comparator based on multisensor fuses |
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2021
- 2021-12-15 CN CN202111534707.7A patent/CN114280350B/en active Active
Patent Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1641365A (en) * | 2004-01-16 | 2005-07-20 | 中国科学院上海应用物理研究所 | Zero-flux current sensor circuit |
| CN203503452U (en) * | 2013-07-31 | 2014-03-26 | 河北申科电子股份有限公司 | Zero-magnetic flux high-accuracy current transformer |
| CN105304303A (en) * | 2015-09-30 | 2016-02-03 | 中国计量科学研究院 | Precise AC-DC large current transformer |
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