A method for verifying the accuracy of a current source for testing a transformer

Abstract

The present application belongs to the technical field of current signal measurement, and particularly relates to a method for verifying the precision of a current source for testing a mutual inductor, which comprises the following steps: obtaining a single-module sampling static resistance, a single-module branch parasitic distributed inductance, and a magnetic ring standard reference total current and a monitoring port summation feedback total voltage at each discrete test frequency point; calculating a single-module dynamic reactance component according to the test signal frequency and the single-module branch parasitic distributed inductance; combining a preset reference frequency to correct the single-module sampling static resistance to obtain a single-module frequency-variable correction resistance, and constructing an impedance complex plane to calculate a single-module equivalent frequency-variable comprehensive impedance; inversely deducing a reconstructed monitoring total current according to the theoretical mapping relationship between the monitoring port summation feedback total voltage and the single-module equivalent frequency-variable comprehensive impedance; and calculating the dynamic comparison relative error of the magnetic ring standard reference total current and the reconstructed monitoring total current, and determining that the verification is qualified if the error is less than or equal to a preset precision threshold. The present method improves the objectivity of verification and evaluation.

Description

Technical Field

[0001] This invention relates to the field of current signal measurement technology. More specifically, this invention relates to a method for verifying the accuracy of a current source for testing a current transformer. Background Technology

[0002] In electrical testing and new energy battery evaluation systems, broadband current sources for transformer testing are not only used for basic transformer verification but also as AC drive devices in testing scenarios such as battery AC heating. Since these devices typically need to cover a wide operating frequency range, the accuracy of their output current directly affects subsequent test results. Therefore, accurate verification of the broadband current source's output current is of significant engineering value for ensuring the reliable operation and subsequent maintenance of the testing system.

[0003] In the prior art, Chinese patent document CN113933593B discloses a system and method for testing the AC equivalent resistance of large-section cable conductors based on a current comparator. This method uses an AC current source to generate a test current and separates and measures the resistive and inductive parameters of the tested object under AC conditions through a current comparator, an amplifier circuit, and an adjustable impedance network, thereby improving the accuracy of AC resistance testing. However, this technology mainly addresses the problem of measuring the AC impedance parameters of the tested conductor, and its test object is an external load circuit. It does not address the impact of changes in parasitic parameters of the sampling network in the multi-module parallel output structure inside the broadband current source on the verification results of the output current.

[0004] In practical engineering scenarios for verifying the accuracy of broadband current sources, since the operating frequency covers the megahertz level, the sampling branches of each parallel module inside the current source will excite the parasitic inductance of the underlying components and traces under the excitation of high-frequency alternating signals. If the existing technology or the traditional pure resistance conversion method is used to verify the output accuracy of the current source, the system will still treat the single-module sampling network as a DC pure resistor, ignoring the physical characteristic that the high-frequency inductive reactance dynamically increases with frequency. Furthermore, it is difficult to distinguish and process the dissipation characteristics of the sampling resistor itself and the inductive impedance generated by the parasitic inductance. This results in the total current value after the voltage at the monitoring port is converted by resistance being unrealistically low in the high-frequency region, which can easily lead to frequent false alarms in daily verification, misjudgment of the current source's output capability, and incorrect fine-tuning of the input operational amplifier circuit. Summary of the Invention

[0005] To address the technical problem in existing current source accuracy verification where the high-frequency parasitic inductive reactance of the single-module sampling branch is ignored, leading to a lower calculated total current, false out-of-tolerance judgments, and operational amplifier error fine-tuning, this invention provides a current source accuracy verification method for current transformers, comprising: S1, obtaining the single-module sampling static resistance and the single-module branch parasitic distributed inductance; at each configured discrete test frequency, obtaining the magnetic ring standard reference total current on the output bus and the monitoring port summation feedback total voltage directly output by the internal operational amplifier adder; S2, calculating the single-module dynamic inductive reactance component based on the test signal frequency of the current test frequency and the single-module branch parasitic distributed inductance; S3, using the test signal of the current test frequency... The frequency is compared with the preset reference frequency to correct the static resistance of the single module sampling, resulting in the frequency-corrected resistance of the single module. An impedance complex plane is constructed based on the frequency-corrected resistance and the dynamic inductive reactance component of the single module. The equivalent frequency-changing comprehensive impedance of the single module is calculated according to the vector magnitude of the impedance complex plane. S4. The theoretical mapping relationship between the monitoring port summation feedback total voltage, the equivalent frequency-changing comprehensive impedance of the single module, and the reconstructed monitoring total current is established, and the reconstructed monitoring total current is deduced accordingly. S5. The magnetic ring standard reference total current and the reconstructed monitoring total current are compared, and the dynamic comparison relative error is calculated. If the dynamic comparison relative error at all test frequencies is less than or equal to the preset accuracy threshold, the monitoring accuracy verification is deemed qualified.

[0006] This invention obtains the static resistance and parasitic distributed inductance of a single module, calculates the dynamic inductive reactance component and frequency-varying correction resistance of the single module using discrete test frequency points, and constructs an impedance complex plane to solve for the equivalent frequency-varying comprehensive impedance of the single module. This method changes the conventional treatment of treating branches as pure DC resistances, taking into account both parasitic inductive reactance and frequency-varying resistance effects. By establishing a mapping relationship between the total feedback voltage and the equivalent frequency-varying comprehensive impedance of the single module, the total monitoring current is reconstructed, thereby completing the comparison and judgment, reducing errors caused by parasitic effects, and improving the objectivity of accuracy assessment.

[0007] Preferably, the calculation of the single-module dynamic reactance component includes: taking the product of twice pi and the test signal frequency at the current test frequency as the test alternating angular frequency; and taking the product of the test alternating angular frequency and the parasitic distributed inductance of the single-module branch as the single-module dynamic reactance component at the current test frequency.

[0008] This invention incorporates the influence of the rate of change of polarity of alternating signals on parasitic characteristics, effectively characterizes high-frequency parasitic effects, overcomes the limitations of a single pure DC resistance model in processing AC high-frequency signals, and provides reliable dynamic input parameters for constructing high-frequency impedance models.

[0009] Preferably, the single-module frequency-varying correction resistor satisfies the expression: In the formula, This is the frequency-varying correction resistor for a single module at the current test frequency. For single-module sampling of static resistance; The test signal frequency at the current test frequency point; To set a preset reference frequency, the lowest test signal frequency among all test frequency points is selected; The frequency-varying correction coefficient is determined by fitting the sampled branch using the least squares method based on the measured AC resistance within the test frequency band.

[0010] This invention constructs a dynamic correction model for a single-module sampling static resistor, avoiding the deviation caused by treating the sampling resistor as a fixed constant in traditional methods, and restoring the true resistive state of the sampling branch under high-frequency alternating conditions.

[0011] Preferably, the construction of the impedance complex plane based on the single-module frequency-varying correction resistor and the single-module dynamic inductive reactance component includes: using the single-module frequency-varying correction resistor at the current test frequency as the real part of the impedance and the single-module dynamic inductive reactance component at the current test frequency as the imaginary part of the impedance to construct the impedance complex plane; in the constructed impedance complex plane, the complex impedance of the single-module sampling branch is expressed as: In the formula, The complex impedance of a single-module sampling branch; , The single-module frequency-varying correction resistor and single-module dynamic inductive reactance component at the current test frequency; It is the imaginary unit.

[0012] Preferably, the calculation of the single-module equivalent frequency-varying composite impedance includes: calculating the squares of the single-module frequency-varying correction resistor and the single-module dynamic inductive reactance component respectively, and taking the arithmetic square root of the sum of their squares as the single-module equivalent frequency-varying composite impedance at the current test frequency.

[0013] Preferably, establishing the theoretical mapping relationship between the total monitoring port summation feedback voltage, the equivalent frequency-varying comprehensive impedance of a single module, and the reconstructed total monitoring current includes: based on the current sharing characteristics of multiple modules in parallel, assuming the reconstructed total monitoring current at the current test frequency is... The total number of parallel single modules is , No. The branch current flowing through each single-module sampling branch is The branch current is in the single-module equivalent frequency-varying composite impedance The branch voltage generated above is ;Will The voltages of each branch are accumulated, and the total voltage of the monitoring port is equal to the product of the total reconstructed monitoring current and the equivalent frequency-varying integrated impedance of the single module.

[0014] This invention derives the theoretical mapping relationship by sorting out the physical process of current shunting at the bus, voltage generation at the sampling stage, and summation at the feedback stage. This reflects the working status of the internal monitoring system and avoids the conversion distortion caused by directly dividing by the static resistance.

[0015] Preferably, the step of reversing the total reconstructed monitoring current includes: dividing the sum of the total feedback voltage at the monitoring port by the equivalent frequency-varying impedance of the single module to obtain the total reconstructed monitoring current at the current test frequency.

[0016] Preferably, the calculation of dynamic comparison relative error includes: calculating the absolute value of the difference between the magnetic ring standard reference total current and the reconstructed monitoring total current at the current test frequency, dividing the absolute value by the magnetic ring standard reference total current and converting it into a percentage form, as the dynamic comparison relative error at the current test frequency.

[0017] Preferably, the discrete test frequency points are obtained by configuring a frequency band covering 5kHz to 1MHz, with a quasi-logarithmic frequency step interval of 1, 2, and 5, namely including 5kHz, 10kHz, 20kHz, 50kHz, 100kHz, 200kHz, 500kHz, and 1MHz.

[0018] This invention configures a discrete test frequency sequence that covers a specific frequency band and is distributed at quasi-logarithmic frequency step intervals. This frequency distribution strategy can maintain appropriate response sensitivity to frequency changes in the low-frequency band and effectively capture the dynamic evolution of parasitic inductance as the frequency increases in the high-frequency range.

[0019] Preferably, the method further includes: if the dynamic comparison relative error of any test frequency point is greater than a preset accuracy threshold, then the monitoring accuracy verification is deemed unqualified, and a verification report containing error data of each test frequency point is generated.

[0020] The beneficial effects of this invention are as follows: This invention introduces the calculation of dynamic inductive reactance components of a single module and processes it in conjunction with the evolution law of the frequency-varying correction resistor of the single module to obtain the equivalent frequency-varying comprehensive impedance of the single module. This provides a physically accurate underlying impedance benchmark for the subsequent current reconstruction process. Based on the current sharing topology and combined with the summation feedback total voltage of the monitoring port, the total monitoring current is reconstructed. This reconstruction process is based on the physical current-combining characteristics of multiple modules in parallel, and reasonably restores the mapping relationship between the summation feedback total voltage of the monitoring port and the actual output total current under alternating operating conditions. This method can reduce the probability of misjudgment caused by high-frequency current distortion, reduce the risk of improper fine-tuning, and provide a reasonable basis for the state diagnosis of the test system. Attached Figure Description

[0021] Figure 1 This is a flowchart of a method for verifying the accuracy of a current source for testing a current transformer, as described in an embodiment of the present invention.

[0022] Figure 2 This is a schematic diagram showing the relative error of the traditional pure resistance conversion method and the reconstructed total current monitoring method of the present invention in a wide frequency range of 5kHz to 1000kHz. Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0024] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0025] This invention discloses a method for verifying the accuracy of a current source tester for a current transformer, referring to... Figure 1 This includes steps S1 to S5: S1. Obtain the electrical and physical parameters at the test frequency.

[0026] It should be noted that when verifying the accuracy of high-current AC output monitoring, the current source of the instrument transformer adopts a multi-module parallel current-sharing mode. The overall process of this step involves configuring a discrete test sequence covering the operating frequency band and acquiring the external reference current and the actual voltage and physical impedance parameters of the internal underlying hardware. For accurate high-frequency impedance compensation, it is necessary to penetrate to the adder output, acquiring not only the static resistance and high-frequency parasitic parameters of a single sampling module, but also directly reading the raw voltage waveform data from the hardware port without secondary system processing. This fundamental and accurate data will provide the initial input for subsequent derivation of the physical process of the branch's high-frequency impedance evolution with frequency.

[0027] Specifically, the drive current source is activated, and a sinusoidal AC test signal is applied to it, configuring a sequence of multiple discrete test frequencies covering the 5kHz to 1MHz frequency band. To comprehensively and accurately capture the dynamic change of parasitic inductance with frequency, fixed test frequency sequences of 5kHz, 10kHz, 20kHz, 50kHz, 100kHz, 200kHz, 500kHz, and 1MHz are selected sequentially according to quasi-logarithmic frequency increments of 1, 2, and 5. At each current test frequency, a standard magnetic ring current probe is connected to the output bus, and the effective current values ​​acquired at each test frequency are simultaneously recorded as the corresponding standard reference total current of the magnetic ring at each frequency.

[0028] Simultaneously, the oscilloscope probe is directly connected to the current monitoring analog output port of the device to read the original analog voltage directly output by the internal operational amplifier adder. The effective value of the waveform is calculated to obtain the monitoring port summation feedback total voltage at each test frequency point with the same amplitude as the magnetic ring standard reference total current. The monitoring port summation feedback total voltage is the underlying hardware potential signal that has not been converted by the DC pure resistance model by the device control system, so as to truly represent the hardware summation state of each parallel module under the current high-frequency operating condition.

[0029] The DC resistance value of the sampling network of a single parallel module was actually measured using a precision resistance tester and used as the static resistance of the single module sampling. Since the multiple parallel modules inside the current source of the transformer maintain strict symmetry and high consistency in PCBA routing layout, component specifications and spatial physical distribution, the parasitic parameters of each branch can be regarded as equivalent. Therefore, in the offline state, the equivalent inductance parameters of the sampling branches of multiple single modules were measured using a high-frequency impedance tester, and their average value was calculated as the parasitic distributed inductance of the single module branch that is common to all parallel branches of the system.

[0030] Thus, the static resistance of the single module sampling, the parasitic distributed inductance of the single module branch, the total reference current of the magnetic ring at each test frequency, and the total feedback voltage of the monitoring port at each test frequency were obtained.

[0031] S2. Calculate the dynamic inductive reactance component of a single module.

[0032] It should be noted that traditional accuracy verification algorithms directly treat the single-module sampling network statically as a pure DC resistor. In actual testing, when a high-frequency alternating signal is applied to the system, the underlying traces and components of the single-module sampling branch inevitably exhibit inherent parasitic inductive characteristics. According to classical AC circuit theory and sinusoidal steady-state analysis of the law of electromagnetic induction, the dynamic inductive reactance generated by an inductor in an AC circuit is numerically equal to the product of the alternating signal angular frequency and the component inductance. Therefore, it is necessary to first derive the test alternating angular frequency reflecting the alternation rate of signal polarity based on the test signal frequency at the test frequency point, and then multiply it by the parasitic distributed inductance of the single-module branch to derive and calculate the inductive reactance bias component that dynamically increases with the current frequency. This process characterizes the previously ignored high-frequency parasitic effects, compensates for the shortcomings of the single pure resistance model, and provides real dynamic input parameters for constructing an accurate high-frequency impedance model.

[0033] Specifically, based on the test signal frequency at the current test frequency and the parasitic distributed inductance of the single-module branch, the dynamic inductive reactance component of the single module at the current test frequency is calculated. The specific calculation formula is as follows:

[0034] In the formula, This refers to the dynamic reactance component of a single module at the current test frequency. Pi is a constant. The test signal frequency at the current test frequency point; This is the parasitic distributed inductance of a single-module branch.

[0035] in, This represents the angular frequency of the test alternating signal, realizing the conversion from linear frequency to angular frequency, reflecting the drastic change of the current test electrical signal over time; while the parasitic distributed inductance of a single module branch... This characterizes the inherent electromagnetic properties of the components and traces themselves, which impede changes in current. The derivation of the single-module dynamic inductive reactance component is based on Faraday's law of electromagnetic induction, where the voltage across the inductor is... When a sinusoidal alternating current is input When, take the derivative with respect to time: When analyzing the AC impedance of a circuit, the focus is on the maximum amplitude of the voltage fluctuation. When the voltage reaches its maximum value, substituting this into the formula for the voltage across the inductor yields the maximum value of the opposition voltage. According to Ohm's law for alternating current, inductive reactance is defined as the ratio of voltage to current, i.e. Therefore, by multiplying the angular frequency of the test alternating signal by the parasitic distributed inductance of the single-module branch, the dynamic inductive reactance component of the single module at the current test frequency is obtained. This demonstrates the actual AC impedance generated by parasitic effects within a single sampling branch under the current specific test frequency band.

[0036] At this point, the dynamic inductive reactance component of the single module at the current test frequency has been obtained.

[0037] S3. Calculate the equivalent frequency-varying composite impedance.

[0038] It should be noted that after obtaining the dynamic inductive reactance of a single module, to reconstruct the true impedance state of the sampling branch under high-frequency alternating conditions, a complex representation of the AC impedance needs to be introduced. Since the resistive component generated by the sampling resistor and the inductive reactance component generated by the parasitic inductance correspond to the active and reactive components in the AC response, respectively, and they differ by 90° in phase, they cannot be directly superimposed using the traditional DC pure resistance model. Furthermore, the non-uniformity of current distribution within the conductor under high-frequency conditions causes the effective resistance of the sampling resistor to increase with frequency. The traditional approach of treating the sampling resistor as a frequency-independent constant will introduce systematic deviations in the high-frequency range. Therefore, when constructing the complex impedance model, a frequency-dependent correction needs to be applied to the real part of the sampling resistor's impedance to simultaneously characterize the true evolution of the resistive and inductive reactance components under high-frequency operating conditions.

[0039] Specifically, based on the measured AC resistance characteristics of the sampling branch within the test frequency band, a frequency-varying correction model is constructed to dynamically correct the static resistance of the single-module sampling circuit, thus obtaining the frequency-varying correction resistance of the single module at the current test frequency. The specific calculation formula is as follows:

[0040] In the formula, This is the frequency-varying correction resistor for a single module at the current test frequency. For single-module sampling of static resistance; The test signal frequency at the current test frequency point; For frequency-varying correction coefficients; To set a preset reference frequency, since the test frequency band covered by the scheme starts from 5kHz, the frequency variation effect is not significant at this time. Therefore, the lowest test signal frequency of all test frequency points is taken as the preset reference frequency, i.e., 5kHz.

[0041] The frequency conversion correction coefficient is determined based on the measured AC resistance of the single-module sampling branch within the test frequency band. The specific calibration method is as follows: Under preset standard load conditions, a high-frequency impedance meter is used to measure the AC resistance of the single-module sampling branch at multiple test frequency points to obtain the measured resistance values ​​at each frequency point; the least squares method is used to fit the relationship curve between the measured resistance and the test frequency, minimizing the sum of squares of the deviations between the fitted resistance value and the measured resistance value at each frequency point in the relationship curve equation, thereby determining the optimal frequency conversion correction coefficient. In this embodiment, after calibration... The value is 0.001. As a correction factor, The fraction characterizes the relative change in frequency. When the test signal frequency equals the reference frequency, the fraction value is 0, and the correction factor is 1, ensuring no correction to the reference point. When the test frequency is much greater than the reference frequency, the fraction value tends towards 1, and the correction factor tends towards... , The introduction of this feature allows the correction magnitude to match the actual physical process, avoiding overcorrection. Characterizing frequency increment, By introducing frequency-weighted normalization, the correction value remains sensitive to frequency changes in the low-frequency band and its growth rate slows down in the high-frequency band, thereby accurately characterizing the frequency-varying characteristics of the sampling resistor in the test frequency band.

[0042] Using the single-module frequency-varying correction resistor at the current test frequency as the real part of the impedance and the single-module dynamic inductive reactance component at the current test frequency as the imaginary part of the impedance, an impedance complex plane is constructed. In the established impedance complex plane, the complex impedance of the single-module sampling branch is expressed as: ;in, The imaginary unit and the real part are... The imaginary part of the impedance reflects the frequency-varying resistive voltage drop component generated by the sampling resistor at high frequencies. This reflects the inductive voltage drop component generated by parasitic inductance. Since the two are orthogonal in the complex plane, their interaction does not satisfy an algebraic superposition relationship, but should be characterized by the magnitude of the complex impedance vector. Therefore, the equivalent frequency-varying composite impedance of the single-module sampling branch at the current test frequency is:

[0043] In the formula, This represents the equivalent frequency-varying composite impedance of a single module at the current test frequency. This is the frequency-varying correction resistor for a single module at the current test frequency. This refers to the dynamic inductive reactance component of a single module at the current test frequency.

[0044] Through the above calculations, the single-module sampling network is transformed from the traditional fixed resistance model into a high-frequency complex impedance model that integrates the frequency-varying resistance effect and parasitic inductance. This avoids the sampling impedance deviation problem caused by ignoring the skin effect and parasitic inductance, and provides an equivalent impedance basis for the accurate conversion of the total output current.

[0045] At this point, the equivalent frequency-varying composite impedance of a single module at the current test frequency is obtained.

[0046] S4. Reconstruct the total monitoring current by back-calculating the theoretical mapping relationship.

[0047] It should be noted that the traditional pure resistance conversion method directly divides the total voltage collected from the monitoring port by the DC static resistance of a single module to calculate the total current. This method ignores the influence of parasitic inductive reactance and skin effect on the sampling resistor under high-frequency operating conditions. In fact, the system adopts a multi-module parallel output architecture. The output bus current is split to each symmetrical module. The voltage signals generated across the independent sampling resistors connected in series in each module branch are buffered and then fed into an operational amplifier adder for linear summation and output to the monitoring port. This forms a physical topology where the current is split in parallel at the bus level, and the voltage is generated independently at the sampling level and summed at the feedback level. Because each module maintains strict symmetry in PCBA layout, component specifications, and trace impedance, each module has equal impedance parallel current sharing characteristics. At the same time, the operational amplifier adder uses equal gain linear summation for the voltage of each branch, and the summation gain is calibrated to 1. The total current actually flowing through the system is evenly distributed to each parallel branch. Each branch current generates a branch voltage across its own equivalent frequency-varying composite impedance. These branch voltages are then accumulated by a hardware operational amplifier adder to form the final feedback total voltage. Therefore, based on the physical mapping mechanism of "equal distribution of total current - voltage division of branch impedance - summation by adder" under the multi-module parallel architecture, it is necessary to perform reverse calculation using the derived equivalent frequency-varying composite impedance to accurately reconstruct the actual total monitoring current corresponding to the internal monitoring system.

[0048] Specifically, for the current test frequency, based on the parallel current sharing characteristics of the internal multi-module circuit and the physical equivalent summation mechanism of the hardware operational amplifier adder, an independent theoretical mapping calculation formula for the total voltage of the monitoring port summation feedback is derived: At the current test frequency, let the total reconstructed monitoring current at the current test frequency, which actually flows through the system and needs to be solved in reverse, be... The total number of parallel single modules is Due to symmetrical current sharing among modules, the first... The branch current flowing through each single-module sampling branch at the current test frequency is: The branch voltage corresponding to this branch current at the current test frequency is: The internal hardware operational amplifier adder will The voltages of each branch are accumulated to obtain the total monitoring and feedback voltage at the current test frequency. The specific calculation formula is as follows:

[0049] In the formula, The summation feedback voltage at the monitoring port under the current test frequency; This represents the total number of single modules connected in parallel within the current source; For the first The branch voltage generated by a single module sampling branch at the current test frequency; The total reconfiguration monitoring current at the current test frequency; This is the equivalent frequency-varying composite impedance of a single module at the current test frequency.

[0050] Subsequently, for the current test frequency, the total monitoring current at the current test frequency is reconstructed by reversing the calculation based on the physical mapping relationship established above. The specific calculation formula is as follows: ;in, This reflects the reconstructed total current value of the monitoring system at the current specific test frequency, after taking into account the parasitic inductance and frequency-varying resistance effects of the internal measurement channels.

[0051] At this point, the total reconfiguration monitoring current at the current test frequency has been obtained.

[0052] S5. Assess whether the monitoring accuracy is up to standard.

[0053] It should be noted that after compensating for and correcting the high-frequency parasitic inductive reactance and frequency-varying resistance effects in the preceding steps, the system has obtained a reconstructed total monitoring current that accurately reflects the characteristics of the internal monitoring channel. By dynamically comparing the reconstructed total monitoring current with the external magnetic ring standard reference total current and calculating the relative error of the dynamic comparison at each frequency point, the measurement consistency of the internal monitoring system at each test frequency point can be quantitatively assessed, providing reliable data support for the closed-loop calibration of the monitoring channel parameters.

[0054] Specifically, based on the absolute value of the difference between the total reference current of the magnetic ring and the total reconstructed monitoring current at the current test frequency, the dynamic comparison relative error at the current test frequency is calculated. The specific calculation formula is as follows:

[0055] In the formula, This represents the dynamic comparison relative error at the current test frequency. This is the standard reference total current of the magnetic ring at the current test frequency. The total reconfiguration monitoring current at the current test frequency; To take the absolute value.

[0056] The absolute difference between the standard reference current of the magnetic ring and the reconstructed monitoring current is calculated to measure the absolute deviation between the external reference measurement results and the reconstructed results of the internal monitoring system. The standard reference current of the magnetic ring is introduced as a reference normalization factor and converted into a percentage relative error, which intuitively reflects the degree of consistency between the internal monitoring channel of the current source and the external standard measurement after considering the high-frequency effect correction.

[0057] If the dynamic comparison relative error at all test frequencies is less than or equal to the preset accuracy threshold, the current current source monitoring accuracy verification is deemed qualified. If the dynamic comparison relative error at any test frequency is greater than the preset accuracy threshold, it indicates that there is a significant deviation between the internal monitoring system and the external reference measurement, and the current current source monitoring accuracy verification is deemed unqualified. A detailed verification report containing the total magnetic ring standard reference current, the reconstructed monitoring total current, and the dynamic comparison relative error at each test frequency will be generated for subsequent fault diagnosis and monitoring channel parameter adjustment.

[0058] It should be noted that, according to the engineering requirements for the stability of broadband high-current source output in electrical testing and new energy battery AC heating systems, the output accuracy needs to be controlled within 1%. Therefore, this embodiment sets the accuracy threshold to 1%. Under this threshold condition, it can effectively tolerate the small tolerance fluctuations of conventional components and sampling circuits during broadband operation, and can also sensitively identify output deviations caused by insulation aging, changes in PCB trace impedance, or performance drift of core power devices.

[0059] For example, Figure 2This diagram illustrates the dynamic comparison of the relative errors between the traditional pure resistance conversion method and the reconstructed total current monitoring method of this invention within a wide frequency range of 5kHz to 1000kHz. In the low-frequency range (5kHz to 50kHz), the traditional pure resistance conversion method shows relatively similar error performance due to the weak influence of parasitic inductance. However, when the frequency increases to the high-frequency range of 500kHz and 1000kHz, the traditional method, by treating multi-module branches as static pure resistances and neglecting the dynamic inductance generated by high-frequency parasitic distributed inductance, results in a larger calculation deviation. At 1000kHz, the error reaches 1.662%, exceeding the 1% threshold. In contrast, the method in this invention reduces the impact of high-frequency impedance deviation, achieving better error control across the entire frequency range and meeting relevant design specifications. This demonstrates, to a certain extent, the effectiveness of the complex impedance reconstruction model in handling high-frequency operating conditions.

Claims

1. A method for verifying the accuracy of a current source tester for a current transformer, characterized in that, include: S1. Obtain the sampling static resistance of a single module and the parasitic distributed inductance of a single module branch; at each configured discrete test frequency, obtain the magnetic ring standard reference total current on the output bus and the monitoring port summation feedback total voltage directly output by the internal operational amplifier adder. S2. Calculate the dynamic inductive reactance component of the single module based on the test signal frequency at the current test frequency point and the parasitic distributed inductance of the single module branch; S3. Correct the single-module sampling static resistance using the test signal frequency of the current test frequency point and the preset reference frequency to obtain the single-module frequency-varying correction resistance; construct an impedance complex plane based on the single-module frequency-varying correction resistance and the single-module dynamic inductive reactance component, and calculate the single-module equivalent frequency-varying comprehensive impedance based on the vector magnitude of the impedance complex plane. S4. Establish the theoretical mapping relationship between the total voltage of the monitoring port summation feedback, the equivalent frequency-varying comprehensive impedance of a single module, and the reconstructed total monitoring current, and deduce the reconstructed total monitoring current based on this relationship. S5. Compare the total reference current of the magnetic ring with the total reconstructed monitoring current and calculate the dynamic comparison relative error. If the dynamic comparison relative error at all test frequencies is less than or equal to the preset accuracy threshold, the monitoring accuracy verification is deemed qualified.

2. The method for verifying the accuracy of a current source for testing a current transformer according to claim 1, characterized in that, The calculation of the dynamic reactance component of a single module includes: The product of twice pi and the test signal frequency at the current test frequency is taken as the test alternating angular frequency; the product of the test alternating angular frequency and the parasitic distributed inductance of the single module branch is taken as the single module dynamic inductive reactance component at the current test frequency.

3. The method for verifying the accuracy of a current source for testing a current transformer according to claim 1, characterized in that, The single-module frequency-varying correction resistor satisfies the following expression: ； In the formula, This is the frequency-varying correction resistor for a single module at the current test frequency. For single-module sampling of static resistance; The test signal frequency at the current test frequency point; To set a preset reference frequency, the lowest test signal frequency among all test frequency points is selected; The frequency-varying correction coefficient is determined by fitting the sampled branch using the least squares method based on the measured AC resistance within the test frequency band.

4. The method for verifying the accuracy of a current source for testing a current transformer according to claim 1, characterized in that, The method of constructing an impedance complex plane based on a single-module frequency-varying correction resistor and a single-module dynamic inductive reactance component includes: Using the single-module frequency-varying correction resistor at the current test frequency as the real part of the impedance and the single-module dynamic inductive reactance component at the current test frequency as the imaginary part of the impedance, an impedance complex plane is constructed. In the constructed impedance complex plane, the complex impedance of the single-module sampling branch is expressed as: In the formula, The complex impedance of a single-module sampling branch; , The single-module frequency-varying correction resistor and single-module dynamic inductive reactance component at the current test frequency; It is the imaginary unit.

5. The method for verifying the accuracy of a current source for testing a current transformer according to claim 1, characterized in that, The calculation of the equivalent frequency-varying composite impedance of a single module includes: Calculate the squares of the single-module frequency-varying correction resistor and the single-module dynamic inductive reactance component respectively, and take the arithmetic square root of the sum of their squares as the single-module equivalent frequency-varying composite impedance at the current test frequency.

6. The method for verifying the accuracy of a current source for testing a current transformer according to claim 1, characterized in that, The establishment of the theoretical mapping relationship between the total voltage of the monitoring port summation feedback, the equivalent frequency-varying comprehensive impedance of a single module, and the reconstructed total monitoring current includes: Based on the current sharing characteristics of multiple modules in parallel, let the total reconstructed monitoring current at the current test frequency be... The total number of parallel single modules is , No. The branch current flowing through each single-module sampling branch is The branch current is in the single-module equivalent frequency-varying composite impedance The branch voltage generated above is ;Will The voltages of each branch are accumulated, and the total voltage of the monitoring port is equal to the product of the total reconstructed monitoring current and the equivalent frequency-varying integrated impedance of the single module.

7. The method for verifying the accuracy of a current source for testing a current transformer according to claim 6, characterized in that, The reverse reconstruction of the total monitored current includes: Divide the sum of the feedback voltage at the monitoring port by the equivalent frequency-varying impedance of the single module to obtain the reconstructed monitoring total current at the current test frequency.

8. The method for verifying the accuracy of a current source for testing a current transformer according to claim 1, characterized in that, The calculation of the dynamic comparison relative error includes: Calculate the absolute value of the difference between the standard reference total current of the magnetic ring and the reconstructed monitoring total current at the current test frequency. Divide the absolute value by the standard reference total current of the magnetic ring and convert it into a percentage. This percentage is used as the dynamic comparison relative error at the current test frequency.

9. The method for verifying the accuracy of a current source for testing a current transformer according to claim 1, characterized in that, The method for obtaining each discrete test frequency point is as follows: The configuration covers the frequency band from 5kHz to 1MHz, with quasi-logarithmic frequency step intervals of 1, 2, and 5, including 5kHz, 10kHz, 20kHz, 50kHz, 100kHz, 200kHz, 500kHz, and 1MHz.

10. The method for verifying the accuracy of a current source for testing a current transformer according to claim 1, characterized in that, The method further includes: If the dynamic comparison relative error of any test frequency point is greater than the preset accuracy threshold, the monitoring accuracy verification is deemed unqualified, and a verification report containing error data for each test frequency point is generated.

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