A current signal detection device

Abstract

The application relates to the technical field of electronic circuits, and discloses a current signal detection device. The current signal is preliminarily detected, a corresponding current conversion and amplification circuit is configured based on the intensity of the current signal obtained through the preliminary detection, a voltage signal corresponding to the strong and weak current signal is obtained through the current conversion and amplification circuit, and a fast Fourier transform is configured to realize the calculation and processing of the voltage signal to obtain a final current detection result.

Description

Technical Field

[0001] This application relates to the field of electronic circuit technology, specifically to a current detection device, and more specifically to a current signal detection device. Background Technology

[0002] In circuits, current signals are a crucial indicator, and accurate detection of them is essential for judging circuit performance. However, due to the complexity and instability of circuits, achieving the required precision is often difficult when detecting these current signals. Researching and exploring current signal detection technologies and equipment is of great significance; how to effectively and accurately detect current signals remains a challenge in the field of electronics. Current signals have a wide range of applications, with numerous AC, DC, and various waveform current signals present in teaching, research, experiments, and production practices. Currently, these current signals are typically acquired through devices such as current sensors. These sensors detect the information of the measured current signal and convert the detected complex and irregular signal according to certain rules, transforming it into a standard electrical signal or other form of signal output for parameter measurement and analysis.

[0003] In the existing technology, the detection of current signals is mainly achieved through electromagnetic detection. However, the detection results of electromagnetic detection are inaccurate, especially for weak current signals, where the detection results differ significantly from the actual results. Therefore, there is a need to provide a device that can accurately detect current signals under various conditions. Summary of the Invention

[0004] To address the aforementioned technical issues, this application provides a current signal detection device that converts and amplifies the current to obtain a voltage signal with adjusted gain. Based on the processing method in the calculation module, harmonic parameters are calculated from the voltage signal with adjusted gain, and the final detection result is determined using the harmonic parameters.

[0005] To achieve the above objectives, the technical solutions adopted in the embodiments of this application are as follows:

[0006] A current signal detection device is provided, which receives a current signal and performs conversion and calculation on the received current signal to obtain the amplitude and frequency of the current. The device includes an initial current measurement module, which is connected to a first conversion module and a second conversion module via switches. The first conversion module and the second conversion module are connected to a calculation module. The initial current measurement module is used to receive the current signal and perform preliminary detection on the frequency of the current signal. Based on the detection result, the type of the current signal is determined. When the frequency of the measured current signal is less than a preset frequency threshold, the current signal is determined to be a weak current signal. When the current signal is a weak current signal, the initial current measurement module is connected to the first conversion module via a switch. When the current signal is a normal current signal, the initial current measurement module is connected to the second conversion module via a switch. A first voltage signal and a second voltage signal corresponding to the weak current signal are obtained through the first conversion module and the second conversion module. The calculation module performs digital-to-analog conversion on the first voltage signal or the second voltage signal based on Fast Fourier Transform to obtain the final current amplitude and frequency.

[0007] Furthermore, the first conversion module is provided with a first operational amplifier circuit connected to the circuit, which is used to amplify the first voltage signal.

[0008] Furthermore, the first conversion module is also provided with a feedback capacitor compensation circuit connected to the first operational amplifier.

[0009] Furthermore, the feedback capacitor compensation circuit includes a feedback resistor connected in parallel with the inverting input of the first operational amplifier and the output of the first operational amplifier, and also includes a feedback capacitor connected in parallel with the feedback resistor.

[0010] Furthermore, the feedback resistor is also connected in parallel with a parasitic capacitor, one end of which is connected to the feedback resistor branch and the other end is grounded.

[0011] Furthermore, the second operational amplifier module includes a second operational amplifier and a PNP transistor connected to the input terminal of the second operational amplifier, wherein the input terminal of the PNP transistor is connected to a voltage buffer.

[0012] Furthermore, the second operational amplifier module also includes a feedback resistor connected to the second operational amplifier.

[0013] Furthermore, the initial current measurement module includes a current sensor.

[0014] Furthermore, the final current amplitude and frequency are obtained by performing digital-to-analog conversion on the first voltage signal or the second voltage signal based on Fast Fourier Transform (FFT), including the following processing steps: extracting the first and second discrete signal segments input to the calculation module; windowing the first and second discrete signal segments; performing DFT processing on the windowed first and second discrete signal segments respectively, selecting the two spectral lines closest to the frequency point to obtain their phase information, calculating the phase difference between the two spectral lines, and solving for the frequency offset based on the phase difference; and estimating the signal parameters based on the frequency offset to obtain the harmonic parameters, i.e., the final current amplitude and frequency.

[0015] Furthermore, windowing processing is performed on the first sequence segment discrete signal and the second sequence segment discrete signal, including adding 4 terms of 5th order Nuttall self-convolution window to the first sequence segment discrete signal and the second sequence segment discrete signal.

[0016] In the technical solution provided in this application embodiment, the current signal is initially detected, and a corresponding current conversion and amplification circuit is configured based on the strength of the current signal obtained from the initial detection. The voltage signal corresponding to the strong and weak current signals is obtained through the current conversion and amplification circuit, and a fast Fourier transform is configured to realize the calculation and processing of the voltage signal to obtain the final current detection result. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] The methods, systems, and / or procedures shown in the accompanying drawings will be further described with reference to exemplary embodiments. These exemplary embodiments will be described in detail with reference to the drawings. These exemplary embodiments are non-limiting exemplary embodiments, wherein example figures represent similar mechanisms in the various views of the drawings.

[0019] Figure 1 This is a schematic diagram of the current signal detection device provided in the embodiments of this application.

[0020] Figure 2 This is a schematic diagram of the circuit structure of the first conversion module provided in the embodiments of this application.

[0021] Figure 3 This is a schematic diagram of the calculation method of the calculation module provided in the embodiment of this application. Detailed Implementation

[0022] To better understand the above technical solutions, the technical solutions of this application will be described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the embodiments of this application and the specific features in the embodiments are detailed descriptions of the technical solutions of this application, rather than limitations on the technical solutions of this application. In the absence of conflict, the embodiments of this application and the technical features in the embodiments can be combined with each other.

[0023] In the detailed description below, numerous specific details are illustrated with examples to provide a comprehensive understanding of the relevant guidance. However, it will be apparent to those skilled in the art that this application can be practiced without these details. In other instances, well-known methods, procedures, systems, components, and / or circuits have been described at a relatively high level without detail to avoid unnecessarily obscuring aspects of this application.

[0024] This application uses flowcharts to illustrate the execution process performed by a system according to embodiments of this application. It should be clearly understood that the execution processes in the flowcharts may not be executed sequentially. Instead, these execution processes may be executed in reverse order or simultaneously. Additionally, at least one other execution process may be added to the flowchart. One or more execution processes may be deleted from the flowchart.

[0025] Before providing a further detailed description of the embodiments of the present invention, the nouns and terms involved in the embodiments of the present invention will be explained, and the nouns and terms involved in the embodiments of the present invention shall be interpreted as follows.

[0026] (1) In response to, used to indicate the conditions or states on which the operation is performed depends. When the conditions or states on which the operation is performed are met, one or more operations may be performed in real time or with a set delay. Unless otherwise specified, there is no restriction on the order in which the multiple operations are performed.

[0027] (2) Based on, used to indicate the conditions or states on which the operation is performed depends. When the conditions or states on which it depends are met, one or more operations can be performed in real time or with a set delay. Unless otherwise specified, there is no restriction on the order of execution of the multiple operations.

[0028] The technical solution provided in this embodiment mainly detects current signals. This current signal detection includes qualitative detection of the presence of a current signal and quantitative detection based on the measurement of specific characteristics of the current signal. In existing detection methods and corresponding devices, current sensors are mainly used to detect current signals in circuits. Current signal detection using current sensors is specifically designed for...

[0029] In view of the above-mentioned prior art background, this embodiment provides a current signal detection device. This system can perform different degrees of conversion and amplification processing on the current signal to obtain the final voltage signal, and obtain the harmonic parameters in the voltage signal through the fast Fourier transform method, and determine the characteristics of the final current signal based on the harmonic parameters.

[0030] In this embodiment, refer to Figure 1 The current detection device includes an initial current measurement module, a first conversion module, and a second conversion module connected to the initial current measurement module. The first and second conversion modules are each connected to a common calculation module. The initial current measurement module serves as the current signal input terminal, and the calculation module serves as the final result output terminal.

[0031] In this embodiment, the calculation module is equipped with a calculation method to process the voltage signals from the first and second conversion modules to obtain amplitude and frequency. The amplitude and frequency are displayed and output through a display device. Therefore, in this embodiment, the device also includes a display terminal for displaying the final output results.

[0032] Specifically, the initial current detection module is connected to the first conversion module and the second conversion module via a switch. It is mainly used to perform preliminary detection of the frequency of the current signal and determine the type of the current signal based on the detection result. When the frequency of the measured current signal is less than a preset frequency threshold, the current signal is determined to be a weak current signal. When the frequency of the current signal is greater than the preset frequency threshold, the current signal is determined to be a normal current signal. When the current signal is a weak current signal, the initial current measurement module is connected to the first conversion module via a switch. When the current signal is a normal current signal, the initial current measurement module is connected to the second conversion module via a switch.

[0033] The first and second conversion modules are used to convert weak current signals and normal current signals into corresponding first and second voltage signals. In this embodiment, the determination of weak and normal current signals can be achieved based on the initial current measurement module, which determines the current signal strength by acquiring the frequency of the current signal. When the frequency of the detected current signal is less than a preset frequency threshold, the current signal is determined to be a weak current signal; when the frequency of the current signal is greater than the preset frequency threshold, the current signal is determined to be a normal current signal. The preset frequency threshold can be determined based on an expert system, and in other embodiments, it can also be determined using machine learning, which will not be elaborated on in this embodiment.

[0034] For the initial current measurement module, which is a current sensor, in this embodiment, the current sensor is hand-wound from enameled wire. The thickness, size, number of coil turns, and core material of the enameled wire can be changed according to the circuit design requirements to meet the measurement circuit requirements. The winding method is simple, low-cost, easy to implement, and convenient to operate. The determination of the thickness, size, and number of coil turns is used to control the measurement range of the current sensor, and will not be elaborated further in this embodiment.

[0035] To enable subsequent detection of different intensity current signals, the circuit structures of the first conversion module and the second conversion module in this embodiment are different.

[0036] Before explaining the current detection of the first and second conversion modules, the principle of current signal detection by the conversion modules will be explained. In this embodiment, the first and second conversion modules mainly perform current-to-voltage conversion on the current signal, amplify the converted voltage signal to obtain an amplified voltage signal, and then process the amplified voltage signal through a calculation module based on Fast Fourier Transform to obtain the final current amplitude and frequency.

[0037] Specifically, the first conversion module is used to convert weak current signals to voltage and then amplify them. In this embodiment, the current-to-voltage conversion and amplification processes are implemented based on a conversion-amplification circuit, see reference [link to relevant documentation]. Figure 2 This embodiment provides a conversion amplifier circuit structure for a first conversion module. The conversion amplifier circuit in the first conversion module includes a first operational amplifier circuit, which amplifies a first voltage signal. It also includes a feedback capacitor compensation circuit connected to the first operational amplifier circuit.

[0038] Specifically, the first operational amplifier circuit includes a first operational amplifier. The feedback capacitor compensation circuit includes a feedback resistor connected in parallel with the inverting input and output of the first operational amplifier, and a feedback capacitor connected in parallel with the feedback resistor. In this embodiment, a parasitic capacitor is also connected in parallel with the feedback resistor, with one end connected to the feedback resistor branch and the other end grounded.

[0039] In this embodiment, the first operational amplifier is designed with high input resistance and extremely low input bias current to prevent noise from the input bias current from drowning out the measured current signal and temperature drift from affecting the stability of the output zero point. Specifically, in this embodiment, the feedback capacitor value is calculated as follows to ensure stable circuit operation:

[0040] NG(j·ω)=1+j·ω·R F ·CS .

[0041] Among these issues, the current-to-voltage conversion process corresponding to weak currents is prone to oscillation in the current-to-voltage conversion circuit. The cause of this oscillation is the input capacitance C of the circuit. S Due to the parasitic capacitance C at the front end s and R F This will create a zero point Z on the noise gain curve. This results in the operational amplifier's open-loop gain curve and noise gain curve intersecting at a rate of 40 dB / dec, causing instability in the operational amplifier, i.e., self-oscillation. To ensure stable circuit operation, this embodiment uses a feedback capacitor C. F As compensation, the feedback capacitor forms a pole in the noise gain curve. This pole causes the closing rate of the noise gain curve and the operational amplifier's open-loop gain curve to roll off by -20 dB / dec, thus meeting the loop stability requirements. When a feedback capacitor is added to the circuit... F Subsequently, the feedback capacitor C F A pole can be formed in the circuit. This capacitor can not only suppress circuit noise, but also prevent the circuit from oscillating.

[0042] This circuit structure enables the conversion and amplification of weak currents.

[0043] The second conversion module includes a second operational amplifier and a PNP transistor connected to the input of the second operational amplifier. A voltage buffer is connected to the input of the PNP transistor, and a feedback resistor is also connected to the second operational amplifier to prevent circuit oscillation. The second conversion module provides a common-mode signal to the input amplifier by applying an input signal to the PNP transistor in the voltage buffer. The amplifier is connected to a precise 50k feedback resistor to ensure adjustable output gain.

[0044] The first voltage signal and the second voltage signal are obtained by the first conversion module and the second conversion module respectively, and the first voltage signal and the second voltage signal are input to the calculation module for final calculation processing.

[0045] In this embodiment, the calculation module performs calculations using the Fast Fourier Transform. (See also...) Figure 3 The process of performing Fast Fourier Transform calculations on the computation module includes the following steps:

[0046] Step S310. Extract the first sequence segment discrete signal and the second sequence segment discrete signal input to the calculation module.

[0047] The time-domain expression for the multi-frequency signal of the first voltage signal or the second voltage signal is as follows:

[0048]

[0049] Among them, f h A h , Let f be the frequency, amplitude, and initial phase of the h-th harmonic. s (f s ≥2f H The discrete signal is obtained by sampling x(t):

[0050]

[0051] Extract a first sequence segment from 1 to N and a second sequence segment from L+1 to L+N, where L is the time-domain shift length of the signal, 0 < L < N < N / 2. The expression for the first sequence segment is:

[0052]

[0053] The expression for the second sequence segment is:

[0054]

[0055] Where n = 1, 2, 3…N-1.

[0056] Step S320. Window the discrete signals of the first sequence segment and the discrete signals of the second sequence segment.

[0057] In this embodiment, the windowing process for the discrete signals of the first sequence segment and the second sequence segment includes adding four 5th-order Nuttall self-convolution windows to the discrete signals of the first sequence segment and the second sequence segment.

[0058] Step S330. Perform DFT processing on the first sequence segment discrete signal and the second sequence segment discrete signal after windowing, select the two spectral lines closest to the frequency point to obtain their phase information, calculate the phase difference between the two spectral lines, and solve the frequency offset based on the phase difference.

[0059] In this embodiment, regarding this step, considering that the long-spectrum leakage of other harmonics has a relatively small impact on the h-th harmonic, and ignoring the influence of negative frequency points, the following is obtained:

[0060]

[0061]

[0062] Where, Δf=f sBecause the fundamental frequency of the power grid signal is not a constant value and varies frequently, asynchronous sampling is often the primary method for sampling power grid signals. Therefore, the actual h-th harmonic frequency, i.e., f... h =k h The spectral peak of Δf is not located at X. w At the discrete frequency points of (k), let the spectral line closest to the h-th harmonic frequency be k. a Let δ = k h -k a Then the k corresponding to the h-th harmonic in the two sequences. a The phase angles are as follows:

[0063]

[0064]

[0065] From the two phase angle expressions above, the phase difference between the first and second sequence segments can be obtained as Δφ. h =φ′ h -φ h We can obtain:

[0066] Δφ h =2πf h L / f s .

[0067] Therefore, the frequency of the h-th harmonic is:

[0068] f h =f s Δφ h / 2πL, then:

[0069] but:

[0070] The corresponding correction formula is:

[0071]

[0072] Step S340. Based on the frequency offset, perform signal parameter estimation to obtain harmonic parameters, i.e., the final current amplitude and frequency.

[0073] Based on the phase correction results obtained in step S330, signal parameters are estimated to obtain the final current amplitude and frequency.

[0074] This embodiment uses the above circuit structure to perform preliminary detection of the current signal, and configures corresponding current conversion and amplification circuits based on the strength of the current signal obtained from the preliminary detection. The voltage signal corresponding to the strong and weak current signals is obtained through the current conversion and amplification circuits, and a fast Fourier transform is configured to realize the calculation and processing of the voltage signal to obtain the final current detection result.

[0075] Those skilled in the art can, without question, determine certain preset, benchmark, predetermined, set, and preference-labeled technical features / terms, such as thresholds, threshold intervals, and threshold ranges, based on the aforementioned disclosed content. For some unexplained technical feature terms, those skilled in the art can reasonably and unambiguously deduce them based on the logical relationship between the context, thereby clearly and completely implementing the aforementioned technical solution. Prefixes of unexplained technical feature terms, such as "first," "second," "example," and "target," can be unambiguously deduced and determined based on the context. Suffixes of unexplained technical feature terms, such as "set" and "list," can also be unambiguously deduced and determined based on the context.

[0076] The content disclosed in the embodiments of this application is clear and complete to those skilled in the art. It should be understood that the process by which those skilled in the art derive and analyze the unexplained technical terms based on the above disclosure is based on the content recorded in this application, and therefore the above content is not a judgment of the inventiveness of the overall solution.

[0077] The basic concepts have been described above. Obviously, for those skilled in the art, the detailed disclosure above is merely illustrative and does not constitute a limitation of this application. Although not explicitly stated herein, those skilled in the art can make various modifications, improvements, and corrections to this application. Such modifications, improvements, and corrections are suggested in this application, and therefore remain within the spirit and scope of the exemplary embodiments of this application.

[0078] Furthermore, this application uses specific terms to describe embodiments of the application. For example, "an embodiment," "one embodiment," and / or "some embodiments" refer to a particular feature, structure, or characteristic associated with at least one embodiment of the application. Therefore, it should be emphasized and noted that "an embodiment," "one embodiment," or "an alternative embodiment" mentioned twice or more in different parts of this specification do not necessarily refer to the same embodiment. In addition, certain features, structures, or characteristics in at least one embodiment of the application can be appropriately combined.

[0079] Furthermore, it will be understood by those skilled in the art that various aspects of this application can be described and illustrated through several patentable types or situations, including any new and useful combination of processes, machines, products, or substances, or any new and useful improvements thereof. Accordingly, various aspects of this application can be implemented entirely by hardware, entirely by software (including firmware, resident software, microcode, etc.), or by a combination of hardware and software. All of the above hardware or software can be referred to as a “unit,” “component,” or “system.” Moreover, various aspects of this application can be embodied as a computer product residing in at least one computer-readable medium, said product including computer-readable program code.

[0080] A computer-readable signal medium may contain a propagated data signal containing computer program encoding, for example, on baseband or as part of a carrier wave. This propagated signal may take various forms, including electromagnetic, optical, and so on, or suitable combinations thereof. A computer-readable signal medium can be any computer-readable medium other than a computer-readable storage medium, which can be connected to an instruction execution system, apparatus, or device to enable communication, propagation, or transmission of a program for use. The program encoding located on the computer-readable signal medium can be propagated through any suitable medium, including radio, cable, fiber optic cable, RF, or similar media, or any combination of the above media.

[0081] The computer program code required for the execution of any aspect of this application can be written in any combination of one or more programming languages, including object-oriented programming languages ​​such as Java, Scala, Smalltalk, Eiffel, JADE, Emerald, C++, C#, VB.NET, Python, etc., or similar conventional programming languages ​​such as the "C" programming language, Visual Basic, Fortran2003, Perl, COBOL 2002, PHP, ABAP, dynamic programming languages ​​such as Python, Ruby, and Groovy, or other programming languages. The program code can be executed entirely on the user's computer, or as a standalone software package on the user's computer, or partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In the latter case, the remote computer can be connected to the user's computer via any network, such as a local area network (LAN) or wide area network (WAN), or connected to an external computer (e.g., via the Internet), or in a cloud computing environment, or used as a service such as Software as a Service (SaaS).

[0082] Furthermore, unless expressly stated in the claims, the order of processing elements and sequences, the use of digits, or other names described in this application are not intended to limit the order of the processes and methods of this application. Although various examples have been discussed in the foregoing disclosure of some embodiments of the invention that are currently considered useful, it should be understood that such details are for illustrative purposes only, and the appended claims are not limited to the disclosed embodiments. Rather, the claims are intended to cover all modifications and equivalent combinations that conform to the substance and scope of the embodiments of this application. For example, while the system components described above can be implemented by hardware devices, they can also be implemented solely by software solutions, such as installing the described system on an existing server or mobile device.

[0083] It should also be understood that, in order to simplify the description disclosed in this application and thus aid in the understanding of at least one embodiment of the invention, multiple features may sometimes be grouped into a single embodiment, drawing, or description thereof in the foregoing description of the embodiments of this application. However, this method of disclosure does not imply that the subject matter of this application requires more features than those mentioned in the claims. In fact, the embodiments contain fewer features than all the features of the single embodiments disclosed above.

Claims

1. A current signal detection device, characterized by, The device comprises an initial current measurement module connected with a first conversion module and a second conversion module through a switch, and the first conversion module and the second conversion module are connected with a calculation module; the initial current measurement module is used for receiving a current signal and performing preliminary detection on the frequency of the current signal, determining the type of the current signal based on the detection result, determining that the current signal is a weak current signal when the detected frequency of the current signal is less than a preset frequency threshold, determining that the current signal is a normal current signal when the frequency of the current signal is greater than the preset frequency threshold, connecting the initial current measurement module with the first conversion module through the switch when the current signal is a weak current signal, and connecting the initial current measurement module with the second conversion module through the switch when the current signal is a normal current signal; the first conversion module and the second conversion module are used for obtaining a first voltage signal and a second voltage signal corresponding to the weak current signal; the calculation module is used for performing digital-to-analog conversion on the first voltage signal or the second voltage signal based on fast Fourier transform to obtain the final amplitude and frequency of the current, and comprises the following processing process: intercepting a first sequence segment discrete signal and a second sequence segment discrete signal input into the calculation module; performing windowing processing on the first sequence segment discrete signal and the second sequence segment discrete signal; performing DFT processing on the windowed first sequence segment discrete signal and the second sequence segment discrete signal, respectively, selecting two spectral lines closest to the frequency point to obtain phase information, calculating the phase difference of the two spectral lines, and solving the frequency offset based on the phase difference; performing signal parameter estimation based on the frequency offset to obtain harmonic parameters, i.e., the final amplitude and frequency of the current; performing windowing processing on the first sequence segment discrete signal and the second sequence segment discrete signal, including adding a 4-term 5-order Nuttall self-convolution window to the first sequence segment discrete signal and the second sequence segment discrete signal.

2. The current signal detection device according to claim 1, characterized in that The first conversion module is provided with a first operational amplifier circuit connected with a circuit, and the first operational amplifier circuit is used for amplifying the first voltage signal.

3. The current signal detection apparatus according to claim 2, characterized by The first conversion module is further provided with a feedback capacitance compensation circuit connected with the first operational amplifier.

4. The current signal detection apparatus according to claim 3, characterized by The feedback capacitance compensation circuit comprises a feedback resistor connected in parallel with an inverting terminal of the first operational amplifier and an output terminal of the first operational amplifier, and further comprises a feedback capacitance connected in parallel with the feedback resistor.

5. The current signal detection apparatus according to claim 4, characterized by The feedback resistor is further connected in parallel with a parasitic capacitance, one end of the parasitic capacitance is connected with the feedback resistor branch, and the other end is grounded.

6. The current signal detection apparatus according to claim 1, characterized by The second operational amplifier module comprises a second operational amplifier and a PNP transistor connected with an input terminal of the second operational amplifier, and the PNP transistor is connected with a voltage buffer.

7. The current signal detection apparatus according to claim 6, characterized by The second operational amplifier module further comprises a feedback resistor connected with the second operational amplifier.

8. The current signal detection device according to any one of claims 1 to 7, characterized in that, The initial current measurement module includes a current sensor.

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