CN115825518A - High-precision universal current measuring device - Google Patents
High-precision universal current measuring device Download PDFInfo
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- CN115825518A CN115825518A CN202310056581.XA CN202310056581A CN115825518A CN 115825518 A CN115825518 A CN 115825518A CN 202310056581 A CN202310056581 A CN 202310056581A CN 115825518 A CN115825518 A CN 115825518A
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Abstract
The invention discloses a high-precision universal current measuring device which comprises a shell, a magnetic core winding structure and a circuit board, wherein the magnetic core winding and the circuit board are arranged in the shell; the circuit board comprises a self-oscillation module, a driving module, a sampling comparison module, a trigger module, a detection module, a signal conditioning module and a general processor module. The current measuring device is based on a low-cost scheme that a zero-flux system is formed by combining a self-oscillation fluxgate technology and a synchronous detection technology to realize high-current precision measurement, and provides three modes of single-path digital output, single-path analog output or digital and analog two-path output; the self-excited oscillation fluxgate of the invention forms an oscillator without an external excitation source, and uses the detection circuit to realize signal extraction, which is very simple compared with the phase sensitive demodulation and peak difference demodulation circuit in the traditional fluxgate technology.
Description
Technical Field
The invention belongs to the technical field of current measuring equipment, and particularly relates to a high-precision universal current measuring device.
Background
Industrial production and scientific research and increasingly wide requirements for precise current measurement, new energy electric vehicles, high-speed rail vehicles, smart grids, UPS systems and the like all need to measure currents from several amperes to thousands of amperes so as to realize real-time monitoring, detection or control of the system. The current sensor is a device for precisely detecting current information in a circuit to be detected, and in practical application, various measuring methods such as a current divider, a Hall effect, a magneto-optical effect, a fluxgate and the like are developed according to different application occasions and performance requirements of current measurement.
The measurement accuracy based on the Hall effect, the magneto-resistance effect and the Faraday magneto-optical effect is relatively low, and the measurement accuracy belongs to the traditional analog measurement and has great limitation conditions in practical application. The shunt method has the main advantages of simple measurement principle and high reliability, and has the defects of incapability of measuring large current, incapability of realizing isolation measurement and high power consumption. In practical application, isolation measurement can be realized by adding an isolation operational amplifier, but new measurement errors can be introduced by the drift and noise of the operational amplifier, the problem of power consumption cannot be solved, and the cost of the isolation operational amplifier is high.
In various current measurement schemes, the method for measuring the current based on the fluxgate principle is a reliable and stable scheme, and the fluxgate sensor has high resolution and a wide measurement range and is widely applied to non-contact current measurement; the traditional fluxgate sensor realizes accurate detection by a magnetic modulation technology, needs an independent excitation source, has a complex demodulation circuit, is easily interfered by external environment, influences measurement precision, and is a problem to be solved on how to realize reliable measurement under the condition of simplifying system complexity; therefore, a high-precision universal current measuring device is provided to solve the problems in the prior art.
Disclosure of Invention
The present invention is directed to a high-precision universal current measuring device to solve the above-mentioned problems of the prior art.
In order to achieve the purpose, the invention adopts the following technical scheme:
a high-precision universal current measuring device comprises a shell, a magnetic core winding structure and a circuit board, wherein the magnetic core winding and the circuit board are arranged inside the shell;
the circuit board comprises a self-oscillation module, a driving module, a sampling comparison module, a trigger module, a detection module, a signal conditioning module and a general processor module;
the self-oscillation module is connected with a magnetic core winding to excite the nonlinear magnetic core to be saturated, when a current to be measured flows through a primary winding, a bias magnetic field is generated in the magnetic core, the symmetry of the excitation current and the excitation magnetic flux is destroyed, and a fluxgate effect is generated;
the magnetic core winding, the driving module, the sampling comparison module and the trigger module form an oscillator;
the driving module is used for driving the magnetic core coil to work in a periodic oscillation mode;
the sampling comparison module is used for comparing the current flowing through the coil with a set threshold value and then outputting a signal to the trigger module;
the detection module converts the current flowing through the coil into a voltage signal and then carries out synchronous sampling;
the signal conditioning module is used for processing the voltage signals, converting the voltage signals into usable analog signals and providing the usable analog signals to the general processor module or directly outputting the usable analog signals from the outside;
the general purpose processor module is used for capturing control signals or analog signals.
Preferably, the magnetic core winding comprises a magnetic core and a coil winding;
the magnetic core is made of soft magnetic materials with high conductivity, low remanence, low coercive force and high squareness ratio, and has no air gap when closed; the coil winding is made of enameled wires with low resistivity, high voltage resistance, stable electrical property and insulating property in a high-temperature environment, and good sealing property and winding property.
Preferably, the driving module is configured as an H-bridge driver.
Preferably, the sampling comparison module samples the current flowing through the coil, compares the current with a set threshold value, and outputs a signal to the trigger module, the trigger module outputs a pulse signal to drive the H bridge to be periodically opened and closed, and the duty ratio of the pulse signal is in proportional relation with the magnitude of the measured current.
Preferably, the signal conditioning module processes the voltage signal, converts the voltage signal into a usable analog signal, and provides the usable analog signal to the general processor module, wherein the amplitude of the analog signal is in proportional relation with the magnitude of the measured current.
Preferably, the H-bridge driver directly drives the magnetic core winding, the H-bridge driver integrates a plurality of N-type MOEFETs, OUT and OUT are connected with the magnetic core winding, the sampling comparison module comprises a sampling module and a comparison module, current flowing through the magnetic core winding is converted into a voltage signal by the sampling module, the signal enters the comparison module to be compared with a set threshold value VREF to output a signal, the output signal enters the trigger module, and the signal is processed and then outputs a driving signal to control the H-bridge driver to work.
Preferably, the H-bridge driver does not have an integrated MOSFET inside, and uses an external separate N-type MOEFET to drive the two half-bridge modules, which are a half-bridge module i and a half-bridge module ii, respectively, and the two half-bridge modules may also use an integrated full-bridge module, or the half-bridge is implemented using two separate MOSFETs;
the first half-bridge module and the second half-bridge module drive a magnetic core winding; the sampling module converts the current flowing through the magnetic core winding into a voltage signal, the voltage signal enters the comparison module to be compared with a set threshold value VREF to output a signal, the output signal enters the trigger module, and the signal is processed and then outputs a driving signal to control the H-bridge driver to work.
Preferably, the detection module comprises a synchronous signal conditioner, a reference source and a junction field effect transistor; the signal conditioning module comprises an amplifier, a feedback network, a conditioning module A and a conditioning module B.
Preferably, the synchronous signal is taken from the output end of the H half bridge, the JFET of the JFET is controlled after the synchronous signal is conditioned by the synchronous signal conditioning, then the reference source is periodically sampled, and the sampling signal enters the conditioning module A;
the sampling module converts the current flowing through the magnetic core winding into a voltage signal, and the voltage signal enters the conditioning module A after being amplified by the amplifier and the feedback network; the conditioning module B is used for signal filtering and outputting an identifiable analog signal to the general processor module or directly outputting the analog signal to an external application.
Preferably, the general-purpose processor module of the current measuring device is arranged to be digital in output and/or analog.
The invention has the technical effects and advantages that: compared with the prior art, the high-precision universal current measuring device provided by the invention has the following advantages:
1. the current measuring device of the invention is based on the low-cost scheme that the self-oscillation fluxgate technology and the synchronous detection technology are combined to form a zero-flux system to realize the high-current precision measurement, an H-bridge driver is used, and the state information is output by the driver internal integrated state monitoring module, so that whether the digital channel works normally can be verified; providing three modes of single-path digital output, single-path analog output or digital and analog two-path output; the analog output channels can work independently of the digital channels.
2. The self-excited oscillation fluxgate forms the oscillator through the trigger, does not need an external excitation source, realizes signal extraction by using the detection circuit, and is very simple compared with a phase sensitive demodulation and peak difference demodulation circuit in the traditional fluxgate technology.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and drawings.
Drawings
Fig. 1 is a schematic view of a fluxgate current measurement structure provided in a first embodiment of the present invention;
fig. 2 is a schematic view of a fluxgate current measurement structure according to a second embodiment of the present invention;
fig. 3 is a schematic view of a fluxgate current measurement structure provided in a third embodiment of the present invention;
fig. 4 is a schematic view of a fluxgate current measurement structure provided in the fourth embodiment of the present invention;
FIG. 5 is a schematic view showing the structure of a core winding and a self-oscillation module according to the present invention
FIG. 6 is another schematic diagram of the core winding and self-oscillating module of the present invention;
FIG. 7 is a schematic diagram of the detecting module and the signal conditioning module according to the present invention.
In the figure: 10. a drive module; 20. a sampling comparison module; 30. a trigger module; 40. a detection module; 50. a signal conditioning module; 60. a magnetic core winding; 70. a general processor module; 80. measuring the current to be measured;
11. a half-bridge module I; 12. a half-bridge module II;
21. a sampling module; 22. a comparison module;
41. conditioning a synchronous signal; 42. a reference source; 43. a junction field effect transistor;
51. an amplifier; 52. a feedback network; 53. a conditioning module A; 54. and a conditioning module B.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. The specific embodiments described herein are merely illustrative of the invention and do not delimit the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The present invention provides the embodiments shown in the figures:
a high-precision universal current measuring device comprises a shell, a magnetic core winding structure and a circuit board, wherein the magnetic core winding 60 and the circuit board are arranged inside the shell;
the circuit board comprises a self-oscillation module, a driving module 10, a sampling comparison module 20, a trigger module 30, a detection module 40, a signal conditioning module 50 and a general processor module 70;
the self-oscillation module is connected with the magnetic core winding 60 to excite the nonlinear magnetic core to be saturated, when a measured current 80 flows in the primary winding, a bias magnetic field is generated in the magnetic core, the symmetry of the excitation current and the excitation magnetic flux is destroyed, and a fluxgate effect is generated;
the magnetic core winding 60, the driving module 10, the sampling comparison module 20 and the trigger module 30 form an oscillator; the trigger module 30 outputs a pulse signal to drive the H bridge to be periodically opened and closed, and the duty ratio of the pulse signal is in proportional relation with the size of the measured current 80;
the driving module 10 is used for driving the magnetic core coil to work in a periodic oscillation mode;
the sampling comparison module 20 is configured to sample a current flowing through the coil, compare the sampled current with a set threshold, and output a signal to the trigger module 30;
the detection module 40 converts the current flowing through the coil into a voltage signal and then performs synchronous sampling;
the signal conditioning module 50 is configured to process the voltage signal, convert the voltage signal into a usable analog signal, and provide the usable analog signal to the general processor module 70; the amplitude of the analog signal is in proportional relation with the size of the measured current 80;
the general purpose processor module 70 is used to capture either control signals or analog signals, where the general purpose processor module 70 must capture control signals, but analog signals may not.
The first embodiment is as follows: as shown in fig. 1, in the present embodiment:
the general purpose processor module 70 captures H-bridge control signals and analog signals, as well as other logic control functions; the general processor module 70 output is a digital output;
example two: unlike the first embodiment, as shown in fig. 2, in the present embodiment:
the general purpose processor module 70 captures H-bridge control signals and analog signals, as well as other logic control functions; the general processor module 70 output is analog output;
example three: unlike the first embodiment, as shown in fig. 3, in the present embodiment:
the general purpose processor module 70 captures H-bridge control signals and analog signals, as well as other logic control functions; the general processor module 70 outputs are digital and analog outputs;
example four: unlike the first embodiment, as shown in fig. 4, in the present embodiment:
the general purpose processor module 70 captures H-bridge control signals, as well as other logic control functions; the general processor module 70 output is a digital output; the signal conditioning module 50 outputs directly as an analog output.
As shown in fig. 5, where the reference numeral 80 is the measured current, the core winding is directly driven by using an H-bridge driver, which integrates 4N-type MOEFETs; the driving module 10 is an H-bridge driver, OUT1 and OUT2 are connected with a magnetic core winding, the sampling comparison module 20 comprises a sampling module 21 and a comparison module 22, the sampling module 21 converts current flowing through the magnetic core winding into a voltage signal, the signal enters the comparison module 22 to be compared with a set threshold value VREF to output a signal, the output signal enters the trigger module 30, and the signal is processed and then outputs a driving signal to control the H-bridge driver to work.
As shown in fig. 6, the reference numeral 80 is the measured current, 4 external discrete N-type MOEFETs are used, the H-bridge driver drives two half-bridge modules, i.e., the first half-bridge module 11 and the second half-bridge module 12, respectively, the two half-bridge modules may also be implemented by using an integrated full-bridge module, or the half-bridge is implemented by using two discrete MOSFETs. Half-bridge module one 11 and half-bridge module two 12 drive the core winding 60. The sampling module 21 converts the current flowing through the core winding into a voltage signal, the voltage signal enters the comparison module 22 to be compared with a set threshold value VREF to output a signal, the output signal enters the trigger module 30, and the signal is processed and then outputs a driving signal to control the H-bridge driver to work.
The detection module 40 comprises a synchronous signal conditioner 41, a reference source 42 and a junction field effect transistor 43; the signal conditioning module 50 includes an amplifier 51, a feedback network 52, a conditioning module a53 and a conditioning module B54;
as shown in fig. 7, the synchronization signal is taken from the output end of the H half bridge, and after being conditioned by the synchronization signal conditioning 41, the synchronization signal controls the JFET of the JFET 43, and then the reference source 42 is periodically sampled, and the sampled signal enters the conditioning module a53. The sampling module 21 converts the current flowing through the magnetic core winding 60 into a voltage signal, and the voltage signal enters the conditioning module a53 after being amplified by the amplifier 51 and the feedback network 52, and the conditioning module a53 has the function of adding the amplified voltage signal and a reference source signal to superpose the voltage signal on a direct current bias. Conditioning module B54 functions to filter the signal and output an analog signal that can be recognized to general processor module 70 or directly to an external use.
In summary, the current measuring device of the present invention combines the self-excited-vibration fluxgate technology and the synchronous detection technology to form a zero-flux system to realize a low-cost scheme of high-current precision measurement, and provides three modes of single-path digital output, single-path analog output, or digital and analog two-path output; the self-oscillation fluxgate of the invention forms an oscillator, an external excitation source is not needed, and a detection circuit is applied to realize signal extraction, thus being very simple compared with a phase sensitive demodulation and peak difference demodulation circuit in the traditional fluxgate technology.
Finally, it should be noted that: although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that modifications may be made to the embodiments or portions thereof without departing from the spirit and scope of the invention.
Claims (10)
1. The utility model provides a general type current measuring device of high accuracy, includes shell, magnetic core winding structure and circuit board, inside the shell was installed to magnetic core winding (60) and circuit board, its characterized in that:
the circuit board comprises a self-oscillation module, a driving module (10), a sampling comparison module (20), a trigger module (30), a detection module (40), a signal conditioning module (50) and a general processor module (70);
the self-oscillation module is connected with a magnetic core winding (60) to excite the nonlinear magnetic core to be saturated, when a measured current (80) flows through a primary winding, a bias magnetic field is generated in the magnetic core, the symmetry of the excitation current and the excitation magnetic flux is destroyed, and a fluxgate effect is generated;
the magnetic core winding (60), the driving module (10), the sampling comparison module (20) and the trigger module (30) form an oscillator;
the driving module (10) is used for driving the magnetic core coil to work in a periodic oscillation mode;
the sampling comparison module (20) is used for sampling the current flowing through the coil, comparing the current with a set threshold value and then outputting a signal to the trigger module (30);
the detection module (40) converts the current flowing through the coil into a voltage signal and then carries out synchronous sampling;
the signal conditioning module (50) is used for processing the voltage signals, converting the voltage signals into usable analog signals and providing the usable analog signals to the general processor module (70) or directly outputting the usable analog signals from the outside;
the general purpose processor module (70) is for capturing control signals or analog signals.
2. A high precision universal current measuring device according to claim 1, characterized in that: the magnetic core winding (60) comprises a magnetic core and a coil winding;
the magnetic core is made of soft magnetic materials, and is closed without an air gap;
the coil winding is made of enameled wires with stable electrical property and insulating property and good sealing property and winding property in a high-temperature environment.
3. A high accuracy universal current measuring apparatus according to claim 1, wherein: the drive module (10) is configured as an H-bridge driver.
4. A high precision universal current measuring device according to claim 3, characterized in that: the sampling comparison module (20) samples the current flowing through the coil, compares the current with a set threshold value, outputs a signal to the trigger module (30), the trigger module (30) outputs a pulse signal to drive the H bridge to be periodically opened and closed, and the duty ratio of the pulse signal is in proportional relation with the size of the measured current (80).
5. A high precision universal current measuring device according to claim 1, characterized in that: the signal conditioning module (50) processes the voltage signal, converts the voltage signal into a usable analog signal, and provides the usable analog signal to the general processor module (70), wherein the amplitude of the analog signal is in proportional relation with the size of the measured current (80).
6. A high precision universal current measuring device according to claim 3, characterized in that: h bridge driver direct drive magnetic core winding, H bridge driver have integrateed 4N type MOEFETs, OUT1 and OUT2 connect the magnetic core winding, sampling comparison module (20) are including sampling module (21) and comparison module (22), and sampling module (21) will flow magnetic core winding current conversion and become voltage signal, and this signal gets into comparison module (22) and the threshold value VREF comparison output signal of settlement, and this output signal gets into trigger module (30), and the signal is handled the back and is exported drive signal control H bridge driver and work.
7. A high precision universal current measuring device according to claim 6, characterized in that: the H-bridge driver is internally provided with no integrated MOSFET and uses 4N-type MOEFETs separated from the outside, the H-bridge driver respectively drives two half-bridge modules, namely a half-bridge module I (11) and a half-bridge module II (12), and the two half-bridge modules can also use one integrated full-bridge module or realize the half-bridge by using two separated MOSFETs;
the half-bridge module I (11) and the half-bridge module II (12) drive a magnetic core winding (60); the sampling module (21) converts the current flowing through the magnetic core winding into a voltage signal, the voltage signal enters the comparison module (22) to be compared with a set threshold value VREF to output a signal, the output signal enters the trigger module (30), and the signal is processed to output a driving signal to control the H-bridge driver to work.
8. A high precision universal current measuring device according to claim 6, characterized in that: the detection module (40) comprises a synchronous signal conditioning (41), a reference source (42) and a junction field effect transistor (43); the signal conditioning module (50) comprises an amplifier (51), a feedback network (52), a conditioning module A (53) and a conditioning module B (54).
9. A high precision universal current measuring device according to claim 8, characterized in that: the synchronous signal is taken from the output end of the H half-bridge, the JFET of the JFET (43) is controlled after the synchronous signal is conditioned (41) through the synchronous signal, then the reference source of the reference source (42) is periodically sampled, and the sampling signal enters a conditioning module A (53);
the sampling module (21) converts the current flowing through the magnetic core winding (60) into a voltage signal, the voltage signal is amplified by the amplifier (51) and the feedback network (52) and then enters the conditioning module A (53), and the conditioning module A (53) is used for adding the amplified voltage signal and a reference source signal to enable the voltage signal to be superposed on a direct current bias; the conditioning module B (54) functions as signal filtering and outputs an identifiable analog signal to the general-purpose processor module (70) or directly to an external use.
10. A high precision universal current measuring device according to any one of claims 1-9, characterized in that: a general-purpose processor module (70) of the current measuring device is arranged for digital output and/or analog.
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| CN202310056581.XA CN115825518A (en) | 2023-01-14 | 2023-01-14 | High-precision universal current measuring device |
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| CN202310056581.XA CN115825518A (en) | 2023-01-14 | 2023-01-14 | High-precision universal current measuring device |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116754820A (en) * | 2023-08-24 | 2023-09-15 | 冰零智能科技(常州)有限公司 | Current detection system and detection method thereof |
| CN117388557A (en) * | 2023-10-25 | 2024-01-12 | 上海盛位电子技术有限公司 | Current sensing device and magnetic modulation method |
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2023
- 2023-01-14 CN CN202310056581.XA patent/CN115825518A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116754820A (en) * | 2023-08-24 | 2023-09-15 | 冰零智能科技(常州)有限公司 | Current detection system and detection method thereof |
| CN116754820B (en) * | 2023-08-24 | 2023-10-24 | 冰零智能科技(常州)有限公司 | Current detection system and detection method thereof |
| CN117388557A (en) * | 2023-10-25 | 2024-01-12 | 上海盛位电子技术有限公司 | Current sensing device and magnetic modulation method |
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