CN113049868B - AC/DC current measuring device and measuring method - Google Patents
AC/DC current measuring device and measuring method Download PDFInfo
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- CN113049868B CN113049868B CN202110258892.5A CN202110258892A CN113049868B CN 113049868 B CN113049868 B CN 113049868B CN 202110258892 A CN202110258892 A CN 202110258892A CN 113049868 B CN113049868 B CN 113049868B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/0092—Arrangements for measuring currents or voltages or for indicating presence or sign thereof measuring current only
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R15/00—Details of measuring arrangements of the types provided for in groups G01R17/00 - G01R29/00, G01R33/00 - G01R33/26 or G01R35/00
- G01R15/14—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks
- G01R15/20—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using galvano-magnetic devices, e.g. Hall-effect devices, i.e. measuring a magnetic field via the interaction between a current and a magnetic field, e.g. magneto resistive or Hall effect devices
- G01R15/205—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using galvano-magnetic devices, e.g. Hall-effect devices, i.e. measuring a magnetic field via the interaction between a current and a magnetic field, e.g. magneto resistive or Hall effect devices using magneto-resistance devices, e.g. field plates
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- Measurement Of Current Or Voltage (AREA)
Abstract
The invention discloses an AC/DC current measuring device and a measuring method, comprising the following steps: the control module comprises a control unit and an analog-to-digital conversion unit, and the control unit is connected with the analog-to-digital conversion unit and is used for outputting square wave signals; the sensing modules comprise a plurality of sensing modules, the input end of each sensing module is connected with the control unit and used for receiving the square wave signals, and the output end of each sensing module is connected with the analog-to-digital conversion unit and used for generating corresponding sensing output voltage signals according to the level states of the square wave signals; the current measuring device does not need to eliminate residual magnetism through key operation, the measured value can directly reflect the actual current value to be measured, and the measuring accuracy is high; the control module outputs square wave signals to the induction module, so that the influence of disturbance of the earth magnetic field is eliminated, and the numerical value of the current to be measured can be accurately measured.
Description
Technical Field
The present invention relates to the field of current measurement technologies, and in particular, to an ac/dc current measurement device and a measurement method implemented by the current measurement device.
Background
At present, a clamp head hall current sensing device of an ac/dc clamp meter in the market needs to be installed at a gap of an iron core (silicon steel sheet, permalloy), when the clamp head clamps into a current wire to be measured, current generates a magnetic field through the wire, the iron core gathers the magnetic field at the gap to be sensed by the hall current sensor, so that corresponding voltage is sensed, a voltage signal is output through a differential amplifier, the voltage signal and the primary current meet a certain linear relation, and the voltage signal is converted into a digital signal through an analog-digital converter to calculate the measured current, so that the purpose of measuring the current is realized. However, the ac-dc clamp meter has the following disadvantages that (1) the iron core belongs to magnetic materials, after the dc-dc large current is measured, the iron core has residual magnetism, the residual magnetism is sensed by the hall current sensor, a certain bias voltage is output, if the influence of the residual magnetism is not removed, the voltage value with bias voltage component is output when the dc-dc current is measured next time, so that the calculated current value can not actually reflect the primary current value, and an inaccurate current value is displayed; (2) Because the iron core has weight, when falling, the position of the Hall current sensing device at the gap of the iron core (silicon steel sheet, permalloy) can be mechanically deviated, so that the induced voltage value can be correspondingly changed, and when severe, the current value calculated by the voltage value is greatly different from the current value of the primary side, and the wrong current value can be displayed; (3) Under the condition of zero current, because of the disturbance of the earth magnetic field, the Hall current sensor can sense different bias voltages due to different geographic positions, the accurate current value can be displayed only by removing the influence of the bias voltages through keys, the operation is complicated, and if the operation is wrong, the current value measurement is directly caused to have deviation.
Disclosure of Invention
The present invention aims to solve the above problems and provide an ac/dc current measurement device.
The present invention also aims to provide an ac/dc current measurement method for the above-mentioned problems.
The technical scheme adopted by the invention for achieving the purpose is as follows:
An ac/dc current measurement device comprising:
The control module comprises a control unit and an analog-to-digital conversion unit, and the control unit is connected with the analog-to-digital conversion unit and is used for outputting square wave signals;
The sensing modules comprise a plurality of sensing modules, the input end of each sensing module is connected with the control unit and used for receiving the square wave signals, and the output end of each sensing module is connected with the analog-to-digital conversion unit and used for generating corresponding sensing output voltage signals according to the level states of the square wave signals;
The first processing unit is connected between the output end of the sensing module and the analog-to-digital conversion unit and is used for receiving the sensing output signal and processing the sensing output voltage signal into a corresponding positive sensitivity output voltage signal and a corresponding negative sensitivity output voltage signal;
The analog-to-digital conversion unit receives and processes the positive sensitivity output voltage signal and the negative sensitivity output voltage signal and outputs the signals to the control unit, and the control unit outputs the value of the current to be detected.
Preferably, the current Ip to be measured is:
wherein, A. b is a positive integer greater than 1, X (n) is an induced output voltage signal of each of the sensing modules when the square wave signal is at a high level, and Y (i) is an induced output voltage signal of each of the sensing modules when the square wave signal is at a low level.
Preferably, the control module further comprises a display unit, and the display unit is connected with the control unit and used for displaying the value of the current to be measured.
Preferably, the first processing unit includes:
the inverting input end of the first operational amplifier is connected with one output end of each sensing module, the non-inverting input end of the first operational amplifier is connected with the other output end of the sensing module, and the output end of the first operational amplifier is connected with the analog-to-digital conversion unit.
Preferably, the sensing module includes:
The resistance value of the magnetic resistance change unit changes along with the magnetic field generated by the current to be measured;
The bridge type driving unit is connected with the magnetic resistance changing unit and used for providing a voltage source for the magnetic resistance changing unit so that the magnetic resistance changing unit generates a differential voltage signal;
The square wave input unit is connected with the magnetic resistance conversion unit at one end, and is connected with the control unit at the other end, and is used for outputting the corresponding induction output voltage signal according to the level state of the square wave signal;
and one end of the second processing unit is connected with the magnetic resistance change unit, and the other end of the second processing unit is connected with the analog-to-digital conversion unit so as to amplify the induction output voltage signal.
Preferably, the magnetic resistance change unit is an AMR magnetic resistance sensor.
Preferably, the second processing unit includes:
the non-inverting input end and the inverting input end of the second operational amplifier are respectively connected with the magnetic resistance change unit;
And the non-inverting input end of the third operational amplifier is connected with the output end of the second operational amplifier, and the output end of the third operational amplifier is connected with the first processing unit and is used for increasing bias voltage for the induction output voltage signal.
Preferably, the power end of the second operational amplifier is connected with one end of a digital controller, and the other end of the digital controller is connected with the control unit, and the control unit is used for setting the amplification factor and the chopper modulation frequency of the second operational amplifier.
Preferably, the bridge driving unit includes:
and one end of the bridge driver circuit is connected with the magnetic resistance change unit, and the other end of the bridge driver circuit is connected with the temperature sensor.
An ac/dc current measurement method, comprising:
The control unit outputs square wave signals;
The induction modules are close to the current to be detected, the induction modules receive the square wave signals, and each induction module outputs a plurality of corresponding induction output voltage signals according to the high-level and low-level states of the square wave signals;
when the square wave signal is in a high level, a plurality of corresponding induction output voltage signals are processed into positive sensitivity output voltage signals through a first processing unit;
When the square wave signal is at a low level, a plurality of corresponding induction output voltage signals are processed into negative sensitivity output voltage signals through the first processing unit;
The first processing unit outputs the positive sensitivity output voltage signal and the negative sensitivity output voltage signal to the analog-to-digital conversion unit for processing, and finally outputs a current value to be detected.
The beneficial effects of the invention are as follows: the invention discloses an AC/DC current measuring device, comprising: the control module comprises a control unit and an analog-to-digital conversion unit, and the control unit is connected with the analog-to-digital conversion unit and is used for outputting square wave signals; the sensing modules comprise a plurality of sensing modules, the input end of each sensing module is connected with the control unit and used for receiving the square wave signals, and the output end of each sensing module is connected with the analog-to-digital conversion unit and used for generating corresponding sensing output voltage signals according to the level states of the square wave signals; the first processing unit is connected between the output end of the sensing module and the analog-to-digital conversion unit and is used for receiving the sensing output signal and processing the sensing output voltage signal into a corresponding positive sensitivity output voltage signal and negative sensitivity output voltage signal; the analog-to-digital conversion unit receives and processes the positive sensitivity output voltage signal and the negative sensitivity output voltage signal and outputs the signals to the control unit, and the control unit outputs the value of the current to be detected. The current measuring device does not need to eliminate residual magnetism through key operation, and the measured value can directly reflect an actual current value to be measured, so that the measuring accuracy is high; the control module outputs square wave signals to the induction module, so that the influence of disturbance of the earth magnetic field is eliminated, and the numerical value of the current to be measured can be accurately measured.
The invention will be further described with reference to the drawings and examples.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following description will briefly explain the embodiments or the drawings needed in the prior art, and it is obvious that the drawings in the following description are only some embodiments of the present invention and that other drawings can be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic diagram of a current measurement device provided by an embodiment of the present invention;
FIG. 2 is a schematic diagram of a current measurement device according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of a first processing unit and a control module according to an embodiment of the present invention;
FIG. 4 is a schematic structural diagram of an induction module according to an embodiment of the present invention;
FIG. 5 is a schematic diagram illustrating a first connection of three sensing modules according to an embodiment of the present invention;
fig. 6 is a schematic diagram of a second connection of three sensing modules according to an embodiment of the present invention.
Detailed Description
In order that the above objects, features and advantages of the invention will be readily understood, a more particular description of the invention will be rendered by reference to the appended drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. The present invention may be embodied in many other forms than described herein and similarly modified by those skilled in the art without departing from the spirit of the invention, whereby the invention is not limited to the specific embodiments disclosed below.
In the description of the present invention, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. indicate orientations or positional relationships based on the drawings, are merely for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present invention.
In the description of the present invention, it should be understood that the terms "first," "second," and the like are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature. In the description of the present invention, the meaning of "plurality" means at least two, for example, two, three, etc., unless specifically defined otherwise.
In the description of the present invention, it will be understood that when an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. In contrast, when an element is referred to as being "directly connected" to another element, there are no intervening elements present.
The AC/DC current measuring device does not need an iron core as a magnetic material to increase the induction intensity of a magnetic field, and the induction module is parallel to the direction of the magnetic field generated by the current to be measured. In the AC/DC current measuring device, the induction module is attached to the clamp head circuit board, and then the clamp head circuit board is fixed on the clamp head cover in a screw driving manner, so that the phenomenon that the wrong current value is displayed due to mechanical position deviation when falling can be avoided. In addition, the induction modules are arranged at different positions on the clamp head circuit board, and because of the disturbance of the earth magnetic field, the induction modules at different positions induce different bias voltages, and the influence of the bias voltages can be eliminated by additionally adding square wave signals, so that a more accurate current value is obtained.
Referring to fig. 1 to 6, an ac/dc current measurement apparatus in an alternative embodiment includes:
the control module 1 comprises a control unit and an analog-to-digital conversion unit, wherein the control unit is connected with the analog-to-digital conversion unit and is used for outputting square wave signals;
the sensing modules 2 comprise a plurality of sensing modules 2, the input end of each sensing module 2 is connected with the control unit and used for receiving the square wave signals, and the output end of each sensing module 2 is connected with the analog-to-digital conversion unit and used for generating corresponding sensing output voltage signals according to the level states of the square wave signals;
The first processing unit is connected between the output end of the sensing module 2 and the analog-to-digital conversion unit, and is used for receiving the sensing output signal and processing the sensing output voltage signal into a corresponding positive sensitivity output voltage signal and negative sensitivity output voltage signal;
The analog-to-digital conversion unit receives and processes the positive sensitivity output voltage signal and the negative sensitivity output voltage signal and outputs the signals to the control unit, and the control unit outputs the value of the current to be detected.
Specifically, the control module 1 is a micro-processing chip, and the model is SWM181RCT6-50, wherein the control unit can output a square wave signal with 300ms pulse width to each sensing module 2 through the flip_drv terminal, so as to be used for positive sensitivity sensing and negative sensitivity sensing of the magnetic resistance change unit.
The control module is arranged in the current measuring device, the first processing unit is arranged in the current measuring device, and the induction module is arranged at the clamp head part of the current measuring device.
The clamp head part of the current measuring device is respectively provided with a left clamp head circuit board and a right clamp head circuit board, and the induction module 2 is respectively and symmetrically attached to the left clamp head circuit board and the right clamp head circuit board. Therefore, the number of the sensing modules 2 is equal to the number of the sensing modules 2 on the left clamp head circuit board and the number of the sensing modules 2 on the right clamp head circuit board.
The A0, A1 and SYNC ends of the control module 1 are connected with the A0, A1 and SYNC ends of the induction module 2 through the left and right clamp head circuit boards, and then the amplification factor and the modulation frequency of a second operational amplifier in the induction module 2 are set through the control module 1; namely, the control module is connected with the sensing module through the clamp head circuit board, and the sensing module is connected with the first processing unit through the clamp head circuit board.
The end A0 and the end A1 of the control module 1 control the end A0 and the end A1 of the sensing module 2, wherein the amplification relationships between the end A1 and the end A0 and the second operational amplifier are shown in table 1:
table 1 A1, amplification relationship of A0 terminal and second operational amplifier
| A1 (level state) | A0 (level state) | Magnification factor |
| 0 | 1 | 20 |
| 1 | 0 | 40 |
| 1 | 1 | 80 |
The SYNC terminal of the control module 1 controls the SYNC terminal of the sensing module 2, wherein the modulation frequency relationship between the SYNC terminal and the second operational amplifier is shown in table 2:
table 2 SYNC amplification relationship of the second operational amplifier
| SYNC | Chopper modulation frequency |
| VDD | Without any means for |
| GND | 200KHz |
In use, the control module 1 sets the amplification factor and the modulation frequency of the second operational amplifier in the sensing module 2, and then the control module 1 outputs a square wave signal with a pulse width of 300ms to the sensing module 2.
Referring to fig. 1 to 6, in an alternative embodiment, the ac/dc current measurement device includes:
wherein, A. b is a positive integer greater than 1, a and b are the sum of the numbers of the sensing modules 2 on the clamp head circuit board, a and b are equal, X (n) is an inductive output voltage signal of each sensing module 2 when the square wave signal is at a high level, and Y (i) is an inductive output voltage signal of each sensing module 2 when the square wave signal is at a low level.
Further, when a has a value of 6 and b has a value of 6 (i.e. 3 sensing modules 2 are on the left clamp head circuit board, 3 sensing modules 2 are on the right clamp head circuit board, and a total of 6 sensing modules 2 are shown as U1, U2, U3, U4, U5, and U6):
when the square wave signal is at high level, the value of the sensing output voltage signal output by the 6 sensing modules 2 is X (n) mV/A
When the square wave signal is at high level, the sensing output voltage signal of the sensing module 2 outputs a positive sensitivity output voltage signal through the first operational amplifier
Wherein V ( Positive direction ) is V ( Positive sensitivity ), and V _offset is bias voltage of the earth magnetic field influence sensing module 2,A bias voltage is added to the sense output voltage signal for the first operational amplifier.
When the square wave signal is at low level, the value of the induction output voltage signal output by the 6 induction modules 2 is Y (i) mV/A, and then:
When the square wave signal is at low level, the sensing output voltage signal of the sensing module 2 outputs a negative sensitivity output voltage signal through the first operational amplifier
Wherein V ( Negative pole ) is V ( negative sensitivity ), and V _offset is bias voltage of the earth magnetic field influence sensing module 2,A bias voltage is added to the sense output voltage signal for the first operational amplifier.
From the above, V ( Negative pole ) minus V ( Positive direction ) can eliminate the bias voltage V _offset generated by the earth magnetic field and the additional bias voltage
Referring to fig. 1 to 6, in an alternative embodiment of the ac/dc current measuring device, the control module 1 further comprises a display unit, which is connected to the control unit for displaying the value of the current to be measured.
The display unit is an LCD module and an LCD display screen and is used for displaying the value of the current to be detected.
Referring to fig. 1 to 6, in an alternative embodiment of the ac/dc current measurement apparatus, the first processing unit includes: the inverting input end of the first operational amplifier U7 is connected with one output end of each sensing module 2, the non-inverting input end of the first operational amplifier U7 is connected with the other output end of the sensing module 2, and the output end of the first operational amplifier U7 is connected with the analog-to-digital conversion unit.
The inverting input terminal of the first operational amplifier U7 is provided with a first impedance (R1, R2, R3, R4, R5, R6) between the inverting input terminal and the output terminal of each sensing module 2, and the resistance value of the first impedance is 12kΩ. A second impedance R7 is disposed between the inverting input terminal of the first operational amplifier U7 and the output terminal of the first operational amplifier U7, and the resistance value of the second impedance R7 is 2kΩ. The non-inverting input end of the first operational amplifier U7 is connected with a third impedance R8 and a fourth impedance R9 in parallel, the third impedance R8 is connected with external bias voltage, the fourth impedance R9 is grounded, wherein the resistance value of the third impedance R8 is 10KΩ, and the resistance value of the fourth impedance R9 is 10KΩ.
Further, the model number of the first operational amplifier U7 is SGM8557.
Referring to fig. 1 to 6, in an alternative embodiment of the ac/dc current measuring apparatus, the sensing module 2 includes:
The resistance value of the magnetic resistance change unit changes along with the magnetic field generated by the current to be measured;
The bridge type driving unit is connected with the magnetic resistance changing unit and used for providing a voltage source for the magnetic resistance changing unit so that the magnetic resistance changing unit generates a differential voltage signal;
The square wave input unit is connected with the magnetic resistance conversion unit at one end, and is connected with the control unit at the other end, and is used for outputting the corresponding induction output voltage signal according to the level state of the square wave signal;
and one end of the second processing unit is connected with the magnetic resistance change unit, and the other end of the second processing unit is connected with the analog-to-digital conversion unit so as to amplify the induction output voltage signal.
Wherein the square wave input unit is a flip coil driver.
Referring to fig. 1 to 6, in an alternative embodiment of the ac/dc current measuring apparatus, the magneto-resistance change unit is an AMR magneto-resistance sensor. The AMR magneto-resistive sensor comprises a resistance bridge, wherein the resistance of the resistance bridge changes along with the change of a magnetic field.
Referring to fig. 1 to 6, in an alternative embodiment of the ac/dc current measuring apparatus, the second processing unit includes:
the non-inverting input end and the inverting input end of the second operational amplifier are respectively connected with the magnetic resistance change unit;
And the non-inverting input end of the third operational amplifier is connected with the output end of the second operational amplifier, and the output end of the third operational amplifier is connected with the first processing unit and is used for increasing bias voltage for the induction output voltage signal.
Referring to fig. 1 to 6, in an alternative embodiment, the power supply end of the second operational amplifier is connected to one end of a digital controller, and the other end of the digital controller is connected to the control unit, so that the control unit sets the amplification factor and chopper modulation frequency of the second operational amplifier.
Referring to fig. 1 to 6, in an alternative embodiment of the ac/dc current measuring apparatus, the bridge driving unit includes:
and one end of the bridge driver circuit is connected with the magnetic resistance change unit, and the other end of the bridge driver circuit is connected with the temperature sensor.
An ac/dc current measurement method, comprising:
The control unit outputs square wave signals;
The induction modules 2 are close to the current to be detected, the induction modules 2 receive the square wave signals, and each induction module 2 outputs a plurality of corresponding induction output voltage signals according to the high and low level states of the square wave signals;
when the square wave signal is in a high level, a plurality of corresponding induction output voltage signals are processed into positive sensitivity output voltage signals through a first processing unit;
When the square wave signal is at a low level, a plurality of corresponding induction output voltage signals are processed into negative sensitivity output voltage signals through the first processing unit;
The first processing unit outputs the positive sensitivity output voltage signal and the negative sensitivity output voltage signal to the analog-to-digital conversion unit for processing, and finally outputs a current value to be detected.
The invention discloses an AC/DC current measuring device, comprising: the control module 1 comprises a control unit and an analog-to-digital conversion unit, wherein the control unit is connected with the analog-to-digital conversion unit and is used for outputting square wave signals; the sensing modules 2 comprise a plurality of sensing modules, the input end of each sensing module 2 is connected with the control unit and used for receiving the square wave signals, and the output end of each sensing module 2 is connected with the analog-to-digital conversion unit and used for generating corresponding sensing output voltage signals according to the level states of the square wave signals; the first processing unit is connected between the output end of the sensing module 2 and the analog-to-digital conversion unit, and is used for receiving the sensing output signal and processing the sensing output voltage signal into a corresponding positive sensitivity output voltage signal and negative sensitivity output voltage signal; the analog-to-digital conversion unit receives and processes the positive sensitivity output voltage signal and the negative sensitivity output voltage signal and outputs the signals to the control unit, and the control unit outputs the value of the current to be detected. The induction module 2 is arranged on the clamp head, and because no magnetic material is adopted, the traditional mode of measuring current by using the iron core material is replaced, the problem of residual magnetism does not exist, the residual magnetism is not needed to be eliminated through key operation, the measured value can directly reflect the actual current value to be measured, and the measurement accuracy is high; the control module 1 outputs square wave signals to the induction module 2, so that the influence of disturbance of the earth magnetic field is eliminated, and the numerical value of the current to be measured can be accurately measured.
It should be understood that, in various embodiments of the present invention, the sequence numbers of the foregoing processes do not mean the order of execution, and the order of execution of the processes should be determined by the functions and internal logic thereof, and should not constitute any limitation on the implementation process of the embodiments of the present invention.
It should also be understood that, in the embodiment of the present invention, the term "and/or" is merely an association relationship describing the association object, indicating that three relationships may exist. For example, a and/or B may represent: a exists alone, A and B exist together, and B exists alone. In addition, the character "/" herein generally indicates that the front and rear associated objects are an "or" relationship.
Those of ordinary skill in the art will appreciate that the elements and algorithm steps described in connection with the embodiments disclosed herein may be embodied in electronic hardware, in computer software, or in a combination of the two, and that the elements and steps of the examples have been generally described in terms of function in the foregoing description to clearly illustrate the interchangeability of hardware and software. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the solution. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.
It will be clear to those skilled in the art that, for convenience and brevity of description, specific working procedures of the above-described systems, apparatuses and units may refer to corresponding procedures in the foregoing method embodiments, and are not repeated herein.
In the several embodiments provided by the present application, it should be understood that the disclosed systems, devices, and methods may be implemented in other manners. For example, the apparatus embodiments described above are merely illustrative, e.g., the division of the units is merely a logical function division, and there may be additional divisions when actually implemented, e.g., multiple units or components may be combined or integrated into another system, or some features may be omitted or not performed. In addition, the coupling or direct coupling or communication connection shown or discussed with each other may be an indirect coupling or communication connection via some interfaces, devices, or elements, or may be an electrical, mechanical, or other form of connection.
The units described as separate units may or may not be physically separate, and units shown as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the embodiment of the present invention.
The technical features of the above-described embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above-described embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.
The above description is only of the preferred embodiment of the present invention, and is not intended to limit the present invention in any way. Any person skilled in the art can make many possible variations and modifications to the technical solution of the present invention or modifications to equivalent embodiments using the methods and technical contents disclosed above, without departing from the scope of the technical solution of the present invention. Therefore, all equivalent changes according to the shape, structure and principle of the present invention are covered in the protection scope of the present invention.
Claims (7)
1. An ac/dc current measurement device comprising: left binding clip circuit board and right binding clip circuit board, its characterized in that still includes:
The control module comprises a control unit and an analog-to-digital conversion unit, and the control unit is connected with the analog-to-digital conversion unit and is used for outputting square wave signals;
The sensing modules comprise a plurality of sensing modules, the number of the sensing modules is even, the input end of each sensing module is connected with the control unit and used for receiving the square wave signals, and the output end of each sensing module is connected with the analog-to-digital conversion unit and used for generating corresponding sensing output voltage signals according to the level states of the square wave signals;
The first processing unit is connected between the output end of the sensing module and the analog-to-digital conversion unit and is used for receiving the sensing output voltage signal and processing the sensing output voltage signal into a corresponding positive sensitivity output voltage signal and a corresponding negative sensitivity output voltage signal;
The analog-to-digital conversion unit receives and processes the positive sensitivity output voltage signal and the negative sensitivity output voltage signal and outputs the signals to the control unit, and the control unit outputs the value of the current to be detected;
The current to be measured The method comprises the following steps:
，
wherein, A and b are positive integers greater than 1,For the inductive output voltage signal of each of the inductive modules when the square wave signal is high,The induction output voltage signal of each induction module is used for detecting the voltage signal when the square wave signal is in a low level;
The induction modules are respectively and symmetrically attached to the left clamp head circuit board and the right clamp head circuit board;
The sensing module includes: the resistance value of the magnetic resistance change unit changes along with the magnetic field generated by the current to be measured; the bridge type driving unit is connected with the magnetic resistance changing unit and used for providing a voltage source for the magnetic resistance changing unit so that the magnetic resistance changing unit generates a differential voltage signal; the square wave input unit is connected with the magnetic resistance change unit at one end, and is connected with the control unit at the other end, and is used for outputting the corresponding induction output voltage signal according to the level state of the square wave signal; one end of the second processing unit is connected with the magnetic resistance change unit, and the other end of the second processing unit is connected with the analog-to-digital conversion unit and is used for amplifying the induction output voltage signal;
The second processing unit includes: the non-inverting input end and the inverting input end of the second operational amplifier are respectively connected with the magnetic resistance change unit; and the non-inverting input end of the third operational amplifier is connected with the output end of the second operational amplifier, and the output end of the third operational amplifier is connected with the first processing unit and is used for increasing bias voltage for the induction output voltage signal.
2. An ac/dc current measuring apparatus according to claim 1, wherein the control module further comprises a display unit connected to the control unit for displaying the value of the current to be measured.
3. An ac/dc current measuring apparatus according to claim 1, wherein the first processing unit comprises:
the inverting input end of the first operational amplifier is connected with one output end of each sensing module, the non-inverting input end of the first operational amplifier is connected with the other output end of the sensing module, and the output end of the first operational amplifier is connected with the analog-to-digital conversion unit.
4. An ac/dc current measuring apparatus according to claim 1, wherein the magneto-resistance changing unit is an AMR magneto-resistance sensor.
5. An ac/dc current measuring apparatus according to claim 1, wherein a power supply terminal of the second operational amplifier is connected to one terminal of a digital controller, and the other terminal of the digital controller is connected to the control unit, for the control unit to set an amplification factor and a chopper modulation frequency of the second operational amplifier.
6. An ac/dc current measuring apparatus according to claim 1, wherein the bridge driving unit comprises:
and one end of the bridge driver circuit is connected with the magnetic resistance change unit, and the other end of the bridge driver circuit is connected with the temperature sensor.
7. An ac/dc current measurement method, implemented by the ac/dc current measurement apparatus according to claim 1, comprising:
The control unit outputs square wave signals;
The induction modules are close to the current to be detected, the induction modules receive the square wave signals, and each induction module outputs a plurality of corresponding induction output voltage signals according to the high-level and low-level states of the square wave signals;
when the square wave signal is in a high level, a plurality of corresponding induction output voltage signals are processed into positive sensitivity output voltage signals through a first processing unit;
When the square wave signal is at a low level, a plurality of corresponding induction output voltage signals are processed into negative sensitivity output voltage signals through the first processing unit;
The first processing unit outputs the positive sensitivity output voltage signal and the negative sensitivity output voltage signal to the analog-to-digital conversion unit for processing, and finally outputs a current value to be detected.
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