Current harmonic measuring device and method

Abstract

The invention discloses a current harmonic measuring device and method. The current harmonic measuring device comprises a main control chip used for collecting the frequency of a measured current and outputting square wave oscillation corresponding to the frequency; the power supply link is used for generating power supply voltage according to the square wave oscillation; the magnetism gathering ring structure is used for converting measured current on a bus penetrating through the magnetism gathering ring structure into a magnetic field; the magnetic sensitive structure is used for carrying out harmonic matching on the magnetic field after receiving the power supply voltage and outputting a harmonic matching value; the operation link is used for performing root mean square calculation on the harmonic matching value; through the positive correlation between the power supply voltage and the sensitivity of the full-bridge magnetic sensitive chip, a current specific frequency harmonic measurement scheme integrating acquisition, extraction and calculation is realized, and the problems that the current harmonic measurement method has high requirements on calculation power and sampling frequency and is difficult to apply to instruments with low performance are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of harmonic measurement, and in particular to a current harmonic measurement device and method. Background Art

[0002] The harmonic content of the power grid is usually measured using specific instruments and methods to detect the harmonic level in the power grid. There are two main methods for measuring harmonics. One is to use the IP-IQ method to detect harmonics in three-phase circuits using phase-locked loop technology. This method can isolate the influence of voltage distortion and obtain accurate detection results. Another method is to analyze waveform data through a harmonic detection method based on Fourier transform. Among them, the IP-IQ method can separate the content of fundamental waves and harmonics, but cannot accurately determine the harmonic content of a specific order. The Fourier transform can obtain each frequency component through calculation, but it has a great impact on the acquisition accuracy, acquisition frequency and operation speed, and has a high requirement for the above performance.

[0003] In summary, the prior art lacks a harmonic measurement method that has lower computing power requirements and sampling frequency requirements. Summary of the invention

[0004] Based on the problems raised by the above background technology, the purpose of the present invention is to provide a current harmonic measurement device and method. By using the positive correlation between the power supply voltage and sensitivity of the full-bridge magnetic sensitive chip, a current specific frequency harmonic measurement solution integrating acquisition, extraction and calculation is realized, which solves the problem that the current current harmonic measurement method has high requirements on computing power and sampling frequency and is difficult to be applied to instruments with lower performance.

[0005] The present invention is achieved through the following technical solutions:

[0006] A first aspect of the present invention provides a current harmonics measuring device, comprising:

[0007] The main control chip is used to collect the frequency of the measured current and output a square wave oscillation corresponding to the frequency;

[0008] A power supply link, used for generating a power supply voltage according to the square wave oscillation;

[0009] A magnetic concentrating ring structure, used for converting the measured current on the busbar passing through the magnetic concentrating ring structure into a magnetic field;

[0010] A magnetic sensitive structure, used for performing harmonic matching on the magnetic field after receiving the supply voltage, and outputting a harmonic matching value;

[0011] A calculation link is used to perform a root mean square calculation on the harmonic matching value to obtain a DC signal, wherein the DC signal is linearly correlated with the measured current harmonic.

[0012] In the above technical solution, the magnetic sensitive structure is used as a link in signal processing, so that the magnetic sensitive sensor collects the signal and then processes it through the post-processing circuit.

[0013] The magnetic concentrating ring structure and the magnetic sensitive structure are combined to form a magnetic tunnel junction, which generates a tunnel magnetoresistance effect. Multiple magnetic tunnel junctions are connected in series, and then multiple series-connected magnetic tunnel junctions are connected to form a full-bridge structure. The full-bridge structure can be used to directly perform multiplication operations on two different physical quantities, which is the technical basis for the current harmonic measurement of the present invention.

[0014] The main control chip sets the detection frequency and outputs a square wave, which is transmitted to the power supply link. The power supply link processes the square wave to obtain a power supply voltage for the magnetic sensitive structure. The magnetic sensitive structure in the full-bridge structure performs matching after receiving the power supply voltage, and transmits the output matching signal to the operation link for RMS calculation. The RMS calculation can obtain a DC current that is linearly related to the harmonics of the measured current.

[0015] In an optional embodiment, the magnetic sensitive structure includes a first magnetic sensitive unit and a second magnetic sensitive unit, and the first magnetic sensitive unit and the second magnetic sensitive unit are both arranged on the magnetic focusing ring structure to achieve voltage temperature drift cancellation.

[0016] In an optional embodiment, the magnetic sensitive unit adopts a magnetic sensitive chip or a device whose sensitivity is linearly related to the power supply voltage. The magnetic focusing ring structure includes a first magnetic focusing ring and a second magnetic focusing ring, the first magnetic sensitive unit is arranged on the first magnetic focusing ring, and the second magnetic sensitive unit is arranged on the second magnetic focusing ring.

[0017] In an optional embodiment, the magnetic focusing ring structure includes a third magnetic focusing ring, and the first magnetic sensitive unit and the second magnetic sensitive unit are symmetrically arranged on the third magnetic focusing ring.

[0018] In an optional embodiment, the first magnetic sensitive unit and the second magnetic sensitive unit adopt a full-bridge magnetic sensor chip.

[0019] In an optional embodiment, the magnetically sensitive structure further includes a first multiplier and a second multiplier;

[0020] The first multiplier is connected to the first magnetic sensitive unit and is used to implement orthogonal phase-locked amplification of the harmonic matching value output by the first magnetic sensitive unit;

[0021] The second multiplier is connected to the second magnetic sensitive unit and is used to implement orthogonal phase-locked amplification of the harmonic matching value output by the second magnetic sensitive unit.

[0022] In an optional embodiment, the power supply link includes a phase shifter and an amplitude conditioning circuit;

[0023] Wherein, the phase shifter is connected to the main control chip and is used to differentiate the square wave oscillation into orthogonal signals;

[0024] The amplitude conditioning circuit is connected to the magnetic sensitive structure and is used for performing amplitude conditioning on the orthogonal signal to generate a power supply voltage to supply power to the magnetic sensitive structure.

[0025] In an optional embodiment, the operation link includes a filter and an operation circuit;

[0026] The filter is connected to the magnetic sensitive unit and is used to filter the harmonic matching value to generate a filtering signal;

[0027] The operation circuit is connected to the main control chip, and is used for performing root mean square calculation on the filtered signal, and extracting a direct current signal which is linearly related to the measured current harmonic from the root mean square calculation result.

[0028] In an optional embodiment, the main control chip performs a frequency sweep operation at an unspecified frequency.

[0029] A second aspect of the present invention provides a current harmonic measurement method, comprising the following steps:

[0030] The main control chip collects the frequency of the measured current and outputs a square wave oscillation corresponding to the frequency;

[0031] The power supply link generates a power supply voltage according to the square wave oscillation;

[0032] The magnetic concentrating ring structure converts the measured current on the busbar passing through the magnetic concentrating ring structure into a magnetic field;

[0033] The magnetic sensitive structure performs harmonic matching on the magnetic field after receiving the supply voltage, and outputs a harmonic matching value;

[0034] The operation link performs a root mean square calculation on the harmonic matching value to obtain a direct current signal, wherein the direct current signal is linearly correlated with the measured current harmonic.

[0035] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0036] By taking advantage of the positive correlation between the power supply voltage and sensitivity of the full-bridge magnetic sensitive chip, a current specific frequency harmonic measurement solution integrating acquisition, extraction and calculation is realized, which solves the problem that the current harmonic measurement method has high requirements on computing power and sampling frequency and is difficult to be applied to instruments with lower performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and should not be regarded as limiting the scope. For those of ordinary skill in the art, other relevant drawings can be obtained based on these drawings without creative work. In the drawings:

[0038] Figure 1 A schematic diagram of the structure of a current harmonics measuring device provided in Embodiment 1 of the present invention;

[0039] Figure 2 A schematic diagram of a flow chart of a current harmonic measurement method provided in Embodiment 2 of the present invention;

[0040] Figure 3 This is a schematic diagram of the principle of an equivalent circuit of a full-bridge structure provided in Example 2 of the present invention. DETAILED DESCRIPTION

[0041] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments and drawings. The exemplary embodiments of the present invention and their description are only used to explain the present invention and are not intended to limit the present invention.

[0042] Example 1

[0043] Figure 1 A schematic diagram of the structure of a current harmonic measurement device provided in Example 1 of the present invention, such as Figure 1 As shown, a current harmonic measurement device comprises:

[0044] The main control chip is used to collect the frequency of the measured current and output a square wave oscillation corresponding to the frequency;

[0045] A power supply link, used for generating a power supply voltage according to the square wave oscillation;

[0046] A magnetic concentrating ring structure, used for converting the measured current on the busbar passing through the magnetic concentrating ring structure into a magnetic field;

[0047] A magnetic sensitive structure, used for performing harmonic matching on the magnetic field after receiving the supply voltage, and outputting a harmonic matching value;

[0048] A calculation link is used to perform a root mean square calculation on the harmonic matching value to obtain a DC signal, wherein the DC signal is linearly correlated with the measured current harmonic.

[0049] It should be noted that, in the first embodiment of the present invention, the magnetic sensitive structure is used as a link in signal processing, so that the magnetic sensitive sensor collects the signal and then processes it through the post-processing circuit.

[0050] The magnetic concentrating ring structure and the magnetic sensitive structure are combined to form a magnetic tunnel junction, which generates a tunnel magnetoresistance effect. Multiple magnetic tunnel junctions are connected in series, and then multiple series-connected magnetic tunnel junctions are connected to form a full-bridge structure. The full-bridge structure can be used to directly perform multiplication operations on two different physical quantities, which is the technical basis for the current harmonic measurement of the present invention.

[0051] The main control chip sets the detection frequency and outputs a square wave, which is transmitted to the power supply link. The power supply link processes the square wave to obtain a power supply voltage for the magnetic sensitive structure. The magnetic sensitive structure in the full-bridge structure performs matching after receiving the power supply voltage, and transmits the output matching signal to the operation link for RMS calculation. The RMS calculation can obtain a DC current that is linearly related to the harmonics of the measured current.

[0052] Compared with existing devices, the current harmonic measurement device provided by the present invention can accurately obtain the harmonic content of a specific order, while having lower requirements on acquisition accuracy, acquisition frequency and operation speed, and greatly improves the measurement accuracy and real-time performance on the basis of existing technologies.

[0053] In an optional embodiment, the magnetic sensitive structure includes a first magnetic sensitive unit and a second magnetic sensitive unit, and the first magnetic sensitive unit and the second magnetic sensitive unit are both arranged on the magnetic focusing ring structure to achieve voltage temperature drift cancellation.

[0054] It should be noted that, since the magnetic sensitive unit required by the present invention is mainly based on the linear correlation between the device sensitivity and the power supply voltage, it is a kind of other device whose sensitivity is linearly related to the power supply voltage.

[0055] In this embodiment, since the voltage generated by the present invention changes with temperature, which leads to voltage instability and reduced accuracy, the first magnetic sensitive unit 101 and the second magnetic sensitive unit 102 are reversed in this embodiment to achieve voltage temperature drift offset.

[0056] In an optional embodiment, the magnetic sensitive unit adopts a magnetic sensitive chip or a device whose sensitivity is linearly related to the power supply voltage. The magnetic focusing ring structure includes a first magnetic focusing ring and a second magnetic focusing ring, the first magnetic sensitive unit is arranged on the first magnetic focusing ring, and the second magnetic sensitive unit is arranged on the second magnetic focusing ring.

[0057] In an optional embodiment, the magnetic focusing ring structure includes a third magnetic focusing ring, and the first magnetic sensitive unit and the second magnetic sensitive unit are symmetrically arranged on the third magnetic focusing ring.

[0058] It should be noted that in this embodiment, the role of the magnetic focusing ring structure is to form a full-bridge structure in combination with the magnetic sensitive unit, and convert the measured current on the bus 001 running through the magnetic focusing ring structure into a magnetic field applied to the magnetic sensitive unit.

[0059] The magnetic focusing ring structure may include a first magnetic focusing ring 002 and a second magnetic focusing ring 003 . The first magnetic focusing ring 002 is provided with a first magnetic sensitive unit 101 , and the second magnetic focusing ring 003 is provided with a second magnetic sensitive unit 102 .

[0060] The magnetic focusing ring structure may also only include the third magnetic focusing ring, and the first magnetic sensitive unit 101 and the second magnetic sensitive unit 102 are symmetrically arranged on the third magnetic focusing ring to achieve voltage temperature drift offset.

[0061] In an optional embodiment, the first magnetic sensitive unit and the second magnetic sensitive unit adopt a full-bridge magnetic sensor chip.

[0062] In an optional embodiment, the magnetically sensitive structure further includes a first multiplier and a second multiplier;

[0063] The first multiplier is connected to the first magnetic sensitive unit and is used to implement orthogonal phase-locked amplification of the harmonic matching value output by the first magnetic sensitive unit;

[0064] The second multiplier is connected to the second magnetic sensitive unit and is used to implement orthogonal phase-locked amplification of the harmonic matching value output by the second magnetic sensitive unit.

[0065] It should be noted that a multiplier is arranged after the magnetic sensitive unit for performing orthogonal phase-locked amplification to reduce the error of the signal during the measurement process.

[0066] In an optional embodiment, the power supply link includes a phase shifter and an amplitude conditioning circuit;

[0067] Wherein, the phase shifter is connected to the main control chip and is used to differentiate the square wave oscillation into orthogonal signals;

[0068] The amplitude conditioning circuit is connected to the magnetic sensitive structure and is used for performing amplitude conditioning on the orthogonal signal to generate a power supply voltage to supply power to the magnetic sensitive structure.

[0069] It should be noted that, in this embodiment, Figure 1As shown, the phase shifter 200 divides the square wave oscillation emitted by the main control chip into two orthogonal signals, one of which is transmitted to the first amplitude conditioning circuit 201, and the first amplitude conditioning circuit 201 performs amplitude conditioning on the orthogonal signal to generate a power supply voltage for the first magnetic sensitive unit 101; the other orthogonal signal is transmitted to the second amplitude conditioning circuit 202, and the second amplitude conditioning circuit 202 performs amplitude conditioning on the orthogonal signal to generate a power supply voltage for the second magnetic sensitive unit 102.

[0070] In an optional embodiment, the operation link includes a filter and an operation circuit;

[0071] The filter is connected to the magnetic sensitive unit and is used to filter the harmonic matching value to generate a filtering signal;

[0072] The operation circuit is connected to the main control chip, and is used for performing root mean square calculation on the filtered signal, and extracting a direct current signal which is linearly related to the measured current harmonic from the root mean square calculation result.

[0073] It should be noted that if Figure 1 As shown, the filter of this embodiment includes a first filter 203 connected to the first magnetic sensitive unit 101 and a second filter 204 connected to the second magnetic sensitive unit 102. The first filter 203 filters the harmonic matching value output by the first magnetic sensitive unit 101 and transmits it to the operation circuit 205, and the second filter 204 filters the harmonic matching value output by the second magnetic sensitive unit 102 and transmits it to the operation circuit 205. After receiving the harmonic matching value after filtering, the operation circuit 205 performs a root mean square calculation on it. The result of the root mean square calculation can extract a DC signal that is linearly related to the measured current harmonics, and complete the current harmonic measurement. After the calculation is completed, the operation circuit 205 sends a signal to the main control chip 300 to start the next current harmonic measurement.

[0074] In an optional embodiment, the main control chip performs a frequency sweep operation at an unspecified frequency.

[0075] It should be noted that, compared with the high requirements of the prior art for the acquisition frequency, the main control chip provided by the embodiment of the present invention can perform frequency sweeping operations at an unspecified frequency, and has a lower requirement for the acquisition frequency.

[0076] Example 2

[0077] Embodiment 2 of the present invention proposes a current harmonic measurement method based on a current harmonic measurement device provided in Embodiment 1, and the process is as follows: Figure 2 As shown, a current harmonic measurement includes the following steps:

[0078] The main control chip collects the frequency of the measured current and outputs a square wave oscillation corresponding to the frequency;

[0079] The power supply link generates a power supply voltage according to the square wave oscillation;

[0080] The magnetic concentrating ring structure converts the measured current on the busbar passing through the magnetic concentrating ring structure into a magnetic field;

[0081] The magnetic sensitive structure performs harmonic matching on the magnetic field after receiving the supply voltage, and outputs a harmonic matching value;

[0082] The operation link performs a root mean square calculation on the harmonic matching value to obtain a direct current signal, wherein the direct current signal is linearly correlated with the measured current harmonic.

[0083] It should be noted that the main control chip collects the measured current, sets its frequency to the frequency of the measured current, and outputs the corresponding square wave oscillation at the frequency, and divides the square wave oscillation into two orthogonal signals through the phase shifter 200, one of which is transmitted to the first amplitude conditioning circuit 201, and the other is transmitted to the second amplitude conditioning circuit 202. After conditioning by the amplitude conditioning circuit, signals V1 and V2 with the same amplitude are obtained. The signals V1 and V2 with the same amplitude are used as the power supply voltages of the first magnetic sensitive unit 101 and the second magnetic sensitive unit 102, respectively.

[0084] The current of the bus 001 can be converted into a magnetic field applied to the first magnetic sensitive unit 101 and the second magnetic sensitive unit 102 by the first magnetic focusing ring 002 and the second magnetic focusing ring 003, that is, the magnetic field is proportional to the measured current. After receiving the power supply voltage, the first magnetic sensitive unit 101 and the second magnetic sensitive unit 102 are matched so that the unit sensitivity of the first magnetic sensitive unit 101 and the second magnetic sensitive unit 102 is the same, and the harmonic matching value is output.

[0085] The value output by the magnetic sensitive unit is processed by low-pass filtering, and the operation link performs RMS processing on the harmonic matching values ​​output by the two groups of magnetic sensitive units. After the main control chip records the signal amplitude after RMS processing, it can switch the output square wave frequency to perform the next current harmonic measurement.

[0086] This method relies on a full-bridge structure composed of magnetic sensitive units. The equivalent circuit diagram of the full-bridge structure is as follows: Figure 2 As shown, R1 and R3 are equivalent to two magnetic tunnel junctions whose resistance is positively correlated with the magnetic field, and R2 and R4 are equivalent to two magnetic tunnel junctions whose resistance is negatively correlated with the magnetic field. At this time, the output of the full-bridge structure is Vout=V+-V-.

[0087] Among them, V+=Vout*R2 / (R1+R2), V-=Vout*R3 / (R3+R4).

[0088] It is not difficult to see that Vout is linearly related to Vcc, that is, the power supply can be regarded as a tunnel magnetoresistance as one input of the multiplier. Secondly, the characteristics of the magnetic tunnel junction itself are linearly related to the magnetic field. After being equivalent to a resistor, this property remains unchanged and can be used as the second input of the multiplier. After having two sets of inputs, directly multiplying two different physical quantities through TMR is the technical basis of this application, and then a complete set of TMR current sensors is formed to realize orthogonal phase-locked amplification and subsequent harmonic measurement.

[0089] In an optional embodiment, the magnetic focusing ring converts the measured current into a magnetic field applied to the magnetic sensitive unit, including:

[0090] H=Bsin(ωt+θ)

[0091] Among them, H is the magnetic field, B is the amplitude of the magnetic induction intensity, ω is the angular frequency of the measured current, t is the time of the measured current, and θ is the phase angle of the measured current.

[0092] The angular frequency of the measured current is the output frequency of the main control chip 300 in this embodiment.

[0093] In an optional embodiment, the magnetic sensitive unit performs harmonic matching on the magnetic field after receiving the power supply voltage, including:

[0094] V out =V cc *V offset +V cc *S*H

[0095] Among them, V out is the harmonic matching value, V cc is the supply voltage of the magnetic sensitive unit, V offset is the unit voltage offset voltage, and S is the unit voltage sensitivity.

[0096] In this embodiment, the supply voltages V1 and V2 are used as the supply voltages of the magnetic sensitive chip 101 and the magnetic sensitive chip 102 respectively. By matching, the unit sensitivity of the magnetic sensitive chip 101 and the magnetic sensitive chip 102 is the same as S, and the output voltages of the two are V out1 and V out2 They are:

[0097] V out1 =Asin(ωt)*S*H+Asin(ωt)*V offset1

[0098] V out2 =Asin(ωt+ip / 2)*S*H+Asin(ωt)*V offset2

[0099] In an optional embodiment, a computing link performs a root mean square calculation on the current harmonic matching value to obtain a DC signal, including:

[0100] The harmonic matching value is filtered by a filter to obtain a filtered signal;

[0101] A root mean square calculation is performed on the filtered signal, and a direct current signal linearly related to the frequency harmonics of the measured current is extracted from the root mean square calculation result.

[0102] It should be noted that the signals Vt1 and Vt2 are obtained by filtering through the filter, and the calculation process is as follows:

[0103] V t1 =A*B*Ssin(θ)

[0104] V t2 =A*B*Scos(θ)

[0105] The same effect as orthogonal phase-locked amplification can be achieved through the RMS circuit, that is, the RMS circuit outputs a DC signal that is linearly related to the harmonics of the measured current with an angular frequency of ω. That is, the main control chip can measure the content of specific frequency harmonics by collecting the signal.

[0106] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A current harmonic measurement device, characterized in that: include: The main control chip is used to collect the frequency of the measured current and output a square wave oscillation corresponding to the frequency; A power supply link, used for generating a power supply voltage according to the square wave oscillation; A magnetic concentrating ring structure, used for converting the measured current on the busbar passing through the magnetic concentrating ring structure into a magnetic field; A magnetic sensitive structure, used for performing harmonic matching on the magnetic field after receiving the supply voltage, and outputting a harmonic matching value; A calculation link is used to perform a root mean square calculation on the harmonic matching value to obtain a DC signal, wherein the DC signal is linearly correlated with the measured current harmonic.

2. A current harmonics measuring device according to claim 1, characterized in that: The magnetic sensitive structure comprises a first magnetic sensitive unit and a second magnetic sensitive unit, wherein the first magnetic sensitive unit and the second magnetic sensitive unit are both arranged on the magnetic focusing ring structure to achieve voltage temperature drift cancellation.

3. A current harmonics measuring device according to claim 2, characterized in that: The magnetic focusing ring structure includes a first magnetic focusing ring and a second magnetic focusing ring. The first magnetic sensitive unit is arranged on the first magnetic focusing ring, and the second magnetic sensitive unit is arranged on the second magnetic focusing ring.

4. A current harmonics measuring device according to claim 2, characterized in that: The magnetic focusing ring structure includes a third magnetic focusing ring, and the first magnetic sensitive unit and the second magnetic sensitive unit are symmetrically arranged on the third magnetic focusing ring.

5. A current harmonics measuring device according to claim 2, characterized in that: The first magnetic sensitive unit and the second magnetic sensitive unit adopt full-bridge magnetic sensor chips.

6. A current harmonics measuring device according to claim 2, characterized in that: The magnetically sensitive structure further includes a first multiplier and a second multiplier; The first multiplier is connected to the first magnetic sensitive unit and is used to implement orthogonal phase-locked amplification of the harmonic matching value output by the first magnetic sensitive unit; The second multiplier is connected to the second magnetic sensitive unit and is used to implement orthogonal phase-locked amplification of the harmonic matching value output by the second magnetic sensitive unit.

7. A current harmonics measuring device according to claim 1, characterized in that: The power supply link includes a phase shifter and an amplitude conditioning circuit; Wherein, the phase shifter is connected to the main control chip and is used to differentiate the square wave oscillation into orthogonal signals; The amplitude conditioning circuit is connected to the magnetic sensitive structure and is used for performing amplitude conditioning on the orthogonal signal to generate a power supply voltage to supply power to the magnetic sensitive structure.

8. The current harmonics measuring device according to claim 1, characterized in that: The operation link includes a filter and an operation circuit; The filter is connected to the magnetic sensitive unit and is used to filter the harmonic matching value to generate a filtering signal; The operation circuit is connected to the main control chip, and is used for performing root mean square calculation on the filtered signal, and extracting a direct current signal which is linearly related to the measured current harmonic from the root mean square calculation result.

9. The current harmonics measuring device according to claim 1, characterized in that: The main control chip performs a frequency sweep operation at an unspecified frequency.

10. A current harmonics measuring method based on a current harmonics measuring device according to any one of claims 1 to 9, characterized in that: The steps include: The main control chip collects the frequency of the measured current and outputs a square wave oscillation corresponding to the frequency; The power supply link generates a power supply voltage according to the square wave oscillation; The magnetic concentrating ring structure converts the measured current on the busbar passing through the magnetic concentrating ring structure into a magnetic field; The magnetic sensitive structure performs harmonic matching on the magnetic field after receiving the supply voltage, and outputs a harmonic matching value; The operation link performs a root mean square calculation on the harmonic matching value to obtain a direct current signal, wherein the direct current signal is linearly correlated with the measured current harmonic.

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