Charger common mode interference detection method and device, electronic equipment and storage medium

Abstract

This application relates to the field of communication technology, and in particular to a method, apparatus, electronic device, and storage medium for detecting common-mode interference in chargers. The method includes: acquiring a preset load switching mode and corresponding load switching conditions; testing the charger under test with initialization parameters to acquire the voltage signal output by the charger under test, and determining background noise spectrum data based on the voltage signal; performing a load switching test on the charger under test based on the preset load switching mode to acquire the response voltage signal of the charger under test within a preset time window; determining a center frequency parameter based on the response voltage signal, and determining a target common-mode interference signal based on the center frequency parameter; and determining the common-mode interference result of the charger under test based on the load switching conditions, the target common-mode interference signal, and the background noise spectrum data. This application improves the accuracy of common-mode interference detection in chargers.

Description

Technical Field

[0001] This application relates to the field of communication technology, and in particular to a method, apparatus, electronic device, and storage medium for detecting common-mode interference in a charger. Background Technology

[0002] Currently, with the increasing frequency and miniaturization of consumer electronic devices, common-mode interference generated by chargers, especially GaN chargers, has become a key factor affecting the sensitivity of touchscreens and the stability of devices. Therefore, common-mode interference testing of chargers during the manufacturing process is an essential quality control step.

[0003] Existing charger interference detection technologies typically acquire and analyze common-mode noise using a fixed oscilloscope range and a fixed frequency band filter under steady-state load or no-load conditions. However, in real-world applications, chargers often face drastic dynamic load changes, such as the instant a phone wakes up. During these events, the charger's switching frequency drifts, and the output voltage drops significantly. This makes it difficult to effectively capture interference signals caused by frequency drift under dynamic loads. Furthermore, the large voltage drop forces the oscilloscope to use a large vertical range, which can mask minute common-mode signals with quantization noise. Therefore, there is room for improvement. Summary of the Invention

[0004] To improve the accuracy of common-mode interference detection in chargers, this application provides a method, apparatus, electronic device, and storage medium for common-mode interference detection in chargers.

[0005] The above-mentioned objective of this application is achieved through the following technical solution:

[0006] A common-mode interference detection method for chargers, the method comprising:

[0007] Obtain the preset load switching mode and the load switching conditions corresponding to the preset load switching mode;

[0008] The charger under test is tested with initialization parameters to obtain the voltage signal output by the charger under test, and the background noise spectrum data is determined based on the voltage signal.

[0009] The test charger is subjected to load switching test based on a preset load switching mode, and the response voltage signal of the test charger within a preset time window is obtained.

[0010] Based on the response voltage signal, determine the center frequency parameter, and based on the center frequency parameter, determine the target common-mode interference signal;

[0011] Based on the load switching conditions, the common-mode interference result of the charger under test is determined according to the target common-mode interference signal and the background noise spectrum data.

[0012] By adopting the above technical solutions, and by acquiring preset load transition modes and conditions, the test conditions can be configurable, thereby simulating various transient impact scenarios encountered by the charger in actual use. By testing the charger under test with initial parameters to determine the background noise spectrum data, an electromagnetic noise floor benchmark for the current test environment can be established, providing a reference for subsequent differential noise reduction and isolating environmental noise from interfering with the test results. By performing load transition tests based on preset load transition modes to obtain response voltage signals, the complete electrical response of the charger under the most severe operating conditions can be actively excited and captured, thus avoiding the potential omissions in traditional static testing methods. By determining the center frequency parameters and the target common-mode interference signal based on the response voltage signal, specific interference components whose frequency dynamically drifts with the load can be tracked and separated from complex broadband signals. By determining the common-mode interference results based on load transition conditions and background noise spectrum data, dynamic threshold determination and environmental noise cancellation based on the severity of the operating conditions can be achieved, thereby significantly improving the accuracy and rationality of the final determination results.

[0013] In a preferred embodiment, this application can be further configured such that the step of determining the center frequency parameter based on the response voltage signal specifically includes:

[0014] The response voltage signal is fitted using a fitting algorithm to obtain the voltage baseline corresponding to the response voltage signal;

[0015] The difference between the response voltage signal and the voltage baseline is calculated to obtain the high-frequency response signal;

[0016] The center frequency parameter is determined by performing time-frequency domain analysis on the high-frequency response signal.

[0017] By adopting the above technical solution, and by using a fitting algorithm to process the response voltage signal to obtain the voltage baseline, the low-frequency trend of millisecond-level large voltage drop or overshoot caused by load transition can be reconstructed. By calculating the difference between the response voltage signal and the voltage baseline to obtain the high-frequency response signal, the large-amplitude low-frequency fluctuations can be removed in a purely software manner without introducing phase distortion from hardware filters. This is equivalent to extending the dynamic range of the oscilloscope in the digital domain, making it possible to analyze the masked weak high-frequency common-mode interference signals.

[0018] In a preferred embodiment, this application can be further configured such that the step of performing time-frequency domain analysis on the high-frequency response signal to determine the center frequency parameter specifically includes:

[0019] The high-frequency response signal is transformed using a time-frequency transformation method to obtain a time-frequency distribution matrix;

[0020] Within the time-frequency distribution matrix, a frequency variation sequence distributed over time is generated based on the frequency point corresponding to the maximum energy amplitude, and the frequency variation sequence is determined as the center frequency parameter.

[0021] By adopting the above technical solution, and using the time-frequency transformation method to transform the high-frequency response signal to obtain the time-frequency distribution matrix, a one-dimensional time-domain signal can be mapped to a two-dimensional time-frequency plane, thereby intuitively showing the dynamic distribution of signal energy with time and frequency. By generating a frequency change sequence based on the frequency point corresponding to the maximum energy amplitude within the time-frequency distribution matrix, the frequency drift trajectory with the most concentrated interference energy can be extracted from complex time-frequency data, ensuring the locking of non-steady-state interference signals.

[0022] In a preferred embodiment, this application can be further configured such that the step of determining the target common-mode interference signal based on the center frequency parameter specifically includes:

[0023] A digital bandpass filter is constructed, wherein the center frequency of the digital bandpass filter is adjusted according to the center frequency parameter, and the passband width of the digital bandpass filter is a preset fixed value;

[0024] The high-frequency response signal is input into the digital bandpass filter for filtering to obtain the target common-mode interference signal.

[0025] By adopting the above technical solution and constructing a digital bandpass filter whose center frequency is adjusted according to the center frequency parameter, the dynamic adaptive following of the filtering window can be achieved, thereby matching and locking the target interference signal whose frequency is drifting. By inputting the high-frequency response signal into the digital bandpass filter for filtering, the common-mode interference component of a specific trajectory can be efficiently separated from broadband noise, thereby greatly improving the signal-to-noise ratio of the target signal and providing a clean data foundation for subsequent accurate quantization and judgment.

[0026] In a preferred embodiment, this application can be further configured such that the step of determining the common-mode interference result of the charger under test based on the load switching condition, the target common-mode interference signal, and the background noise spectrum data specifically includes:

[0027] Obtain the signal spectrum data of the target common-mode interference signal, calculate the difference between the signal spectrum data and the background noise spectrum data, and determine the net interference data;

[0028] Based on the load transition conditions, the corresponding common-mode interference determination threshold is obtained;

[0029] Based on the net interference data and the common-mode interference determination threshold, the common-mode interference result of the charger under test is determined.

[0030] By adopting the above technical solution, the net interference data is determined by calculating the difference between the target common-mode interference signal and the background noise spectrum data. This effectively eliminates the superposition effect of the inherent electromagnetic background noise of the test environment on the measurement results, thus ensuring that the final analysis is based solely on the real interference generated by the charger under test. By matching the corresponding common-mode interference judgment threshold according to the load switching conditions, dynamic standard judgment based on the severity of the operating conditions can be achieved. This avoids the misjudgment that may occur under severe operating conditions or the omission that may occur under mild operating conditions when using a single fixed threshold, making the judgment results more reasonable.

[0031] In a preferred embodiment, this application can be further configured such that the step of determining the common-mode interference result of the charger under test based on the net interference data and the common-mode interference determination threshold specifically includes:

[0032] Monitor the amplitude of the net interference data;

[0033] If all of the amplitude values ​​are below the common-mode interference determination threshold, then the common-mode interference result is determined to be qualified.

[0034] If the amplitude is higher than the common-mode interference determination threshold, the autocorrelation coefficient of the net interference data within a preset time period is calculated, and it is determined whether the autocorrelation coefficient meets the preset similarity condition.

[0035] If the autocorrelation coefficient satisfies the preset similarity condition, then the common-mode interference result is determined to be unqualified.

[0036] If the autocorrelation coefficient does not meet the preset similarity condition, then the common-mode interference result is determined to be qualified.

[0037] By adopting the above technical solution, the autocorrelation coefficient of the net interference data is calculated when the amplitude exceeds the threshold, which enables secondary identification of the exceeding signal from the perspective of waveform morphology, thereby quantifying its periodic repetitive characteristics. By determining whether the autocorrelation coefficient meets the preset similarity condition to determine the final result, it is possible to distinguish between the periodic real common-mode interference continuously generated by the switching power supply and the non-periodic random glitches or overshoots caused by relay operation or power grid surges, thereby greatly reducing the false positive rate in automated testing and improving the accuracy and reliability of testing.

[0038] In a preferred embodiment, this application can be further configured such that, after the step of determining the target common-mode interference signal, the charger common-mode interference detection method further includes:

[0039] Obtain the physical parameters of the cable in the current test link;

[0040] Based on the center frequency parameter and the cable physical parameter, a dynamic attenuation compensation coefficient corresponding to the frequency at each time point is matched in a preset frequency attenuation mapping table.

[0041] The target common-mode interference signal is dynamically amplitude corrected using the dynamic attenuation compensation coefficient.

[0042] By adopting the above technical solution, the physical parameters of the current test link cable can be obtained, and the physical properties of the hardware can be incorporated into the algorithm model, thus laying the foundation for compensation. By matching the dynamic attenuation compensation coefficient with the center frequency parameter and the cable physical parameters, the dynamic loss of the signal due to frequency changes during transmission can be calculated in real time, thus solving the problem that fixed coefficient compensation cannot adapt to frequency drift scenarios. By using the dynamic attenuation compensation coefficient to dynamically correct the amplitude of the target common-mode interference signal, the signal energy lost due to cable attenuation can be restored, thus ensuring that the measurement results are not affected by the length of the test cable or the level of the interference frequency, and guaranteeing the consistency and comparability of the test results.

[0043] The second objective of this invention is achieved through the following technical solution:

[0044] A charger common-mode interference detection system, the charger common-mode interference detection system comprising:

[0045] The hardware link unit includes an AC power input interface, an isolation transformer, an EMI power frequency filter, a fixture switching module, and an oscilloscope connected sequentially along the signal transmission direction.

[0046] The control terminal is communicatively connected to the fixture switching module and the oscilloscope, and is used to execute the charger common-mode interference detection method as described above.

[0047] By adopting the above technical solution and setting up a hardware link unit that includes an isolation transformer and an EMI power frequency filter, large-amplitude power frequency interference can be suppressed and ground loops can be eliminated at the physical level, thereby creating a good initial signal-to-noise ratio environment for subsequent digital signal processing. By configuring the control terminal to execute the aforementioned method, complex signal processing algorithms can be combined with hardware control to build a complete test system that can automatically perform high-precision dynamic common-mode interference detection.

[0048] The above-mentioned objective three of this application is achieved through the following technical solution:

[0049] An electronic device includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the steps of the charger common-mode interference detection method described above.

[0050] The fourth objective of this application is achieved through the following technical solution:

[0051] A computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps of the charger common-mode interference detection method described above.

[0052] In summary, this application includes at least one of the following beneficial technical effects:

[0053] 1. By acquiring preset load transition modes and conditions, the test conditions can be configurable, simulating various transient impact scenarios encountered by the charger in actual use. By testing the charger under test with initial parameters to determine background noise spectrum data, an electromagnetic noise floor benchmark for the current test environment can be established, providing a reference for subsequent differential noise reduction and isolating environmental noise from interfering with the test results. By performing load transition tests based on preset load transition modes to obtain response voltage signals, the complete electrical response of the charger under the most severe conditions can be actively excited and captured, thus avoiding potential omissions in traditional static testing methods. By determining the center frequency parameters and target common-mode interference signals based on the response voltage signals, specific interference components whose frequencies dynamically drift with the load can be tracked and separated from complex broadband signals. By determining the common-mode interference results based on load transition conditions and background noise spectrum data, dynamic threshold judgment and environmental noise cancellation based on the severity of the operating conditions can be achieved, significantly improving the accuracy and rationality of the final judgment results.

[0054] 2. By acquiring the physical parameters of the cable in the current test link, the physical properties of the hardware can be incorporated into the algorithm model, thus laying the foundation for compensation. By matching the dynamic attenuation compensation coefficient with the center frequency parameter and the cable physical parameters, the dynamic loss of the signal due to frequency changes during transmission can be calculated in real time, thus solving the problem that fixed coefficient compensation cannot adapt to frequency drift scenarios. By using the dynamic attenuation compensation coefficient to dynamically correct the amplitude of the target common-mode interference signal, the signal energy lost due to cable attenuation can be restored, thus ensuring that the measurement results are not affected by the length of the test cable or the level of the interference frequency, and guaranteeing the consistency and comparability of the test results. Attached Figure Description

[0055] Figure 1This is a schematic block diagram of a charger common-mode interference detection system according to one embodiment of this application;

[0056] Figure 2 This is a flowchart illustrating the implementation of a common-mode interference detection method for chargers in one embodiment of this application;

[0057] Figure 3 This is a flowchart illustrating the implementation of step S40 in a charger common-mode interference detection method according to an embodiment of this application.

[0058] Figure 4 This is a flowchart illustrating the implementation of step S43 in a charger common-mode interference detection method according to an embodiment of this application.

[0059] Figure 5 This is another implementation flowchart of step S40 in the charger common-mode interference detection method in one embodiment of this application;

[0060] Figure 6 This is a flowchart illustrating the implementation of step S50 in a charger common-mode interference detection method according to an embodiment of this application.

[0061] Figure 7 This is a flowchart illustrating the implementation of step S53 in a charger common-mode interference detection method according to an embodiment of this application.

[0062] Figure 8 This is a flowchart illustrating the implementation after step S40 in the charger common-mode interference detection method in one embodiment of this application.

[0063] Figure 9 This is a schematic diagram of the internal structure of an electronic device according to an embodiment of this application. Detailed Implementation

[0064] The following embodiments will help those skilled in the art to further understand the function of this application, but do not limit this application in any way. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of this application. These all fall within the protection scope of this application.

[0065] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application may also be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods have been omitted so as not to obscure the description of this application with unnecessary detail.

[0066] It should be understood that, when used in this application specification and the appended claims, the term "comprising" indicates the presence of the described features, integrals, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or a collection thereof.

[0067] The present application will be further described in detail below with reference to the accompanying drawings.

[0068] In one embodiment, such as Figure 1 As shown, this embodiment provides a charger common-mode interference detection system, which establishes the hardware foundation for performing high-precision common-mode interference testing. The detection system mainly includes a hardware link unit and a control terminal. The hardware link unit includes, in sequence along the signal transmission direction, a mains input interface, an isolation transformer, an EMI power frequency filter, a fixture switching module, and an oscilloscope.

[0069] AC power input interface, used for connecting AC220V / 50Hz AC mains power.

[0070] An isolation transformer is connected to the mains input interface and can be used with a 1:1 turns ratio. Its function is to cut off the electrical connection between the mains ground wire and the subsequent test circuit ground wire, eliminate ground loop interference, and ensure test safety and signal purity.

[0071] An EMI power frequency filter is connected to the output of the isolation transformer. This filter is configured to have high attenuation characteristics (e.g., attenuation greater than 40dB) for 50Hz / 60Hz power frequencies and their lower harmonics. Its function is to filter out large-amplitude power frequency noise at the hardware level, preventing it from entering the oscilloscope and causing the vertical range to be excessively widened, thus reserving dynamic range for subsequent capture of small common-mode signals.

[0072] The fixture switching module is located between the filter and the charger under test (DUT). This module includes a multi-channel relay array and corresponding load resistors, supporting simultaneous connection of multiple DUTs, such as up to four. By switching the relays, power supply and testing can be performed on both the left and right devices in a polling manner.

[0073] An electronic load is connected to the output terminal of the charger under test, such as a Type-C port. This electronic load features a programmable dynamic mode, capable of generating a step current with extremely short rise / fall times, such as <1μs, to simulate the instantaneous operation of a mobile phone under heavy load. Simultaneously, the electronic load has a synchronous trigger port for outputting a hardware trigger signal synchronized with the load transition.

[0074] An oscilloscope is used to directly acquire the voltage at the output terminal of the charger under test via a differential or common-mode probe. It is important to note that this embodiment does not use a traditional hardware bandpass filter such as a 400kHz hardware filter; the oscilloscope acquires a broadband raw voltage signal that has undergone EMI filtering but not high-frequency filtering. The oscilloscope's trigger source is set to external triggering, connected to the synchronous trigger port of the electronic load.

[0075] The control terminal communicates with the fixture switching module and the oscilloscope. It is typically an industrial control computer with dedicated testing software installed. It communicates with the electronic load, oscilloscope, and fixture switching module via USB, GPIB, or LAN interfaces, respectively, to issue test commands and read waveform data.

[0076] In one embodiment, such as Figure 2 As shown, this application discloses a common-mode interference detection method for chargers, applied to the aforementioned common-mode interference detection system for chargers. The common-mode interference detection method for chargers specifically includes the following steps:

[0077] S10. Obtain the preset load switching mode and the load switching conditions corresponding to the preset load switching mode.

[0078] Specifically, by reading the user configuration interface or the pre-stored test configuration file, the dynamic load change type and specific electrical parameter indicators used in this test are parsed out. The load switching mode represents the trend type of load change, such as different operating conditions such as switching from light load to full load, switching from no load to half load, or switching from heavy load to light load. The load switching condition further quantifies the specific physical parameters under this mode, such as the starting current value, the ending current value, the slope of the current change, and the duration of the switching action.

[0079] S20. Test the charger under test with the initialization parameters, obtain the voltage signal output by the charger under test, and determine the background noise spectrum data based on the voltage signal.

[0080] Specifically, control commands are sent to the electronic load to make it operate in an initial steady-state mode with constant current or constant voltage. For example, the load is controlled to maintain a low current state of 0.1A to simulate the standby state of the charger. In this stable operating state, the data acquisition process is started to record the time-domain voltage waveform at the output of the charger under test. Then, frequency domain transformation processing is performed on the time-domain voltage waveform to generate a data set describing the electromagnetic noise distribution characteristics under the current test environment, i.e., background noise spectrum data. This data characterizes the inherent interference reference introduced by the test cable, fixture and surrounding environment.

[0081] S30. Perform load switching test on the charger under test based on the preset load switching mode, and obtain the response voltage signal of the charger under test within the preset time window.

[0082] Specifically, based on the preset load switching mode, a corresponding dynamic control sequence is generated and sent to the electronic load to drive the electronic load to perform transient current switching actions, such as raising the load current to the maximum value in a very short time. The signal edge generated at the moment of this current switching is used as the trigger source to synchronously start the data acquisition process, lock and record the voltage data in a continuous time period including a stable period before the switching moment and an oscillation recovery period after the switching moment. The acquired raw data is the response voltage signal, which completely records the transient response process of the output voltage of the charger under test when facing severe load fluctuations. It includes low-frequency voltage drop or overshoot components, power frequency ripple components, and high-frequency common-mode interference components superimposed on them.

[0083] S40. Determine the center frequency parameter based on the response voltage signal, and determine the target common-mode interference signal based on the center frequency parameter.

[0084] Specifically, signal separation and feature tracking processing is performed on the response voltage signal. First, the low-frequency trend term with large amplitude and the weak high-frequency oscillation term in the response voltage signal are separated by data processing logic, retaining the high-frequency component. Then, time-frequency domain joint analysis is performed on the high-frequency component to identify the frequency drift trajectory or frequency distribution characteristics of the interference energy over time. The dataset describing the frequency change law is determined as the center frequency parameter. Finally, the center frequency parameter is used to construct a frequency-variable signal extraction mechanism to accurately extract specific signal components that match the frequency change law from the high-frequency components, thereby obtaining the target common-mode interference signal that contains only the broadband clutter removed by the charger switching action.

[0085] S50. Based on the load transition condition, determine the common-mode interference result of the charger under test according to the target common-mode interference signal and background noise spectrum data.

[0086] Specifically, the frequency domain features of the extracted target common-mode interference signal are compared with the background noise spectrum data obtained in the previous steps to offset the superposition effect of environmental noise on the measured amplitude, thereby obtaining net signal data that reflects the true interference intensity. At the same time, according to the load jump conditions in the previous steps, the corresponding tolerance thresholds in the preset judgment standard library are used. For example, a wider threshold is matched for severe working conditions such as full-load jumps, and a stricter threshold is matched for slight jumps. Finally, the intensity features of the net signal data are compared with the matched tolerance thresholds, and logical judgment is made in combination with the periodicity or continuity characteristics of the waveform. The common-mode interference result that characterizes whether the electromagnetic compatibility performance of the charger under test is qualified is output.

[0087] In one embodiment, such as Figure 3 As shown, in step S40, which is the step of determining the center frequency parameter based on the response voltage signal, the specific steps include:

[0088] S41. Using a fitting algorithm, the response voltage signal is fitted to obtain the voltage baseline corresponding to the response voltage signal.

[0089] Specifically, the polynomial fitting function in the numerical computation library is called, and a preset order, such as 3rd to 5th, is set, with time... The independent variable is the amplitude of the response voltage signal. Using the least squares method as the dependent variable, the polynomial coefficients are solved iteratively to construct a smooth curve function that best matches the overall trend of the response voltage signal. Alternatively, a moving average algorithm with a preset window width can be used to calculate the mean of the response voltage signal through a sliding window, filtering out high-frequency ripple details and retaining only the low-frequency profile. Whether it is a numerical sequence calculated by a polynomial function or a smoothed sequence obtained by moving average, it is determined as the voltage baseline. This baseline numerically describes the large drop or recovery process of the voltage at the moment of load jump.

[0090] S42. Calculate the difference between the response voltage signal and the voltage baseline to obtain the high-frequency response signal.

[0091] Specifically, a point-by-point subtraction operation based on the time series is performed for each sampling point in the response voltage signal. Find the voltage baseline value at the corresponding time. Execute the formula The calculation involves further improving the signal-to-noise ratio. Additionally, to further enhance the signal-to-noise ratio, pre-identified power frequencies such as 50Hz or 60Hz and their lower harmonic components can be selectively subtracted from the difference, ultimately generating a numerical sequence. This is a high-frequency response signal. The low-frequency bias at the level of hundreds of millivolts has been removed from the signal numerically, leaving only the high-frequency oscillation component at the level of millivolts, thereby achieving compression of the signal's dynamic range and extraction of effective information.

[0092] S43. Perform time-frequency domain analysis on the high-frequency response signal to determine the center frequency parameter.

[0093] Specifically, the high-frequency response signal is processed by frame segmentation using the Short Time Fourier Transform (SFT) algorithm. A sliding time window with a preset overlap rate, such as 50%, is set. The SFT algorithm is applied to the data segment within each time window, and the square of its spectral magnitude is calculated to obtain the power spectral density, thereby constructing a three-dimensional time-frequency distribution matrix containing time axis, frequency axis, and energy amplitude axis. Next, the time-frequency distribution matrix is ​​subjected to ridge extraction operation, that is, traversing each time slice in the matrix and searching for the frequency index value with the largest energy amplitude in the spectral vector corresponding to each time slice, and converting the index value into the corresponding physical frequency value. Finally, the physical frequency values ​​extracted from all time slices are concatenated in chronological order, and isolated noise points are removed by a smoothing filtering algorithm to form a continuous frequency trajectory curve that changes with time. The numerical sequence describing this trajectory curve is determined as the center frequency parameter, which records the frequency drift path of the interference signal during load transition.

[0094] In one embodiment, such as Figure 4 As shown, in step S43, which involves performing time-frequency domain analysis on the high-frequency response signal to determine the center frequency parameters, the specific steps include:

[0095] S431. By using the time-frequency transformation method, the high-frequency response signal is transformed to obtain the time-frequency distribution matrix.

[0096] Specifically, a short-time Fourier transform is performed on a discrete high-frequency response signal sequence. The specific operation involves setting a length of... For example, a 256-point sliding time window function such as the Hanning window or the Hamming window, with a step size... For example, 128 points are used to slide and extract data frames on the signal sequence. A fast Fourier transform is performed on the windowed data of each frame, and the magnitude or power spectral density of the transform result is calculated. The spectral results of all frames are arranged in chronological order to construct a two-dimensional numerical matrix. The row index of this matrix corresponds to the frequency element, the column index corresponds to the time frame, and the matrix element value represents the signal energy intensity at that time and frequency. This completes the mathematical mapping from the one-dimensional time domain to the two-dimensional time-frequency domain, that is, the time-frequency distribution matrix is ​​obtained.

[0097] S432. Within the time-frequency distribution matrix, based on the frequency point corresponding to the maximum energy amplitude, generate a frequency change sequence that varies with time, and determine the frequency change sequence as the center frequency parameter.

[0098] Specifically, the feature extraction algorithm based on energy ridges is executed, traversing each column of the time-frequency distribution matrix generated in step S431, i.e., each time frame. The element with the largest value is searched in the spectrum data of the current column, and the frequency coordinate value corresponding to the element is recorded as the instantaneous center frequency at that moment. After completing the search of all columns, a set of frequency values ​​arranged in chronological order is obtained. In order to eliminate the influence of outliers, median filtering or polynomial smoothing can be further performed on the set. Finally, a continuous or quasi-continuous trajectory data of frequency changing with time is generated, which is the frequency change sequence. This sequence describes the movement path of the interference signal energy peak on the time axis and is directly determined as the center frequency parameter.

[0099] In one embodiment, such as Figure 5 As shown, in step S40, which is the step of determining the target common-mode interference signal based on the center frequency parameter, the specific steps include:

[0100] S44. Construct a digital bandpass filter, wherein the center frequency of the digital bandpass filter is adjusted according to the center frequency parameter, and the passband width of the digital bandpass filter is a preset fixed value.

[0101] Specifically, a digital bandpass filter model with variable parameters is constructed, such as an infinite impulse response filter or a finite impulse response filter, and a fixed passband width parameter is set, such as... The center frequency change sequence obtained in step S432 is used as the center frequency control variable of the filter, so that the passband center of the filter can be adjusted in real time by following the frequency drift path of the interference signal point by point or segment by segment, and always aligned with the frequency band where the interference signal energy is most concentrated.

[0102] S45. Input the high-frequency response signal into a digital bandpass filter for filtering to obtain the target common-mode interference signal.

[0103] Specifically, the high-frequency response signal obtained in step S42 is used as the input data stream and sent to the digital bandpass filter constructed in step S44 to perform time-domain convolution operation or difference equation iteration operation. During the operation, the filter is configured according to the coefficients at the current time, allowing only frequency components within the dynamic passband to pass through, while significantly attenuating background noise and clutter signals outside the passband. After processing by this time-varying system, the waveform data at the output end is the target common-mode interference signal.

[0104] In one embodiment, such as Figure 6 As shown, in step S50, which is the step of determining the common-mode interference result of the charger under test based on the load switching condition, the target common-mode interference signal, and the background noise spectrum data, the specific steps include:

[0105] S51. Obtain the signal spectrum data of the target common-mode interference signal, calculate the difference between the signal spectrum data and the background noise spectrum data, and determine the net interference data.

[0106] Specifically, a fast Fourier transform is performed on the target common-mode interference signal in the time domain to obtain its frequency domain amplitude spectrum, i.e., the signal spectrum data. Then, the background noise spectrum data stored in step S20 is read, and a frequency-based spectrum subtraction operation is performed, i.e., the amplitude of the signal spectrum data is subtracted from the amplitude of the background noise spectrum data. For frequency points where the difference is less than zero, the difference is set to zero to eliminate the negative spectrum component. Finally, an inverse fast Fourier transform is performed on the processed difference spectrum to reconstruct the time domain waveform sequence. This sequence is the net interference data after removing the influence of environmental background noise, representing the real interference waveform generated only by the internal circuit of the charger under test.

[0107] S52. Based on the load switching conditions, the corresponding common-mode interference judgment threshold is obtained.

[0108] Specifically, the pre-stored mapping table is accessed, and the load switching conditions obtained in step S10 are used as the query index. For example, when the load switching condition is a full-load step, a higher voltage threshold such as 50mV is indexed, and when the load switching condition is a light-load fine-tuning, a lower voltage threshold such as 30mV is indexed, thereby matching the common-mode interference judgment threshold that is adapted to the severity of the current test conditions.

[0109] S53. Based on the net interference data and the common-mode interference judgment threshold, determine the common-mode interference result of the charger under test.

[0110] Specifically, the statistical characteristic values ​​of the net interference data, such as the absolute maximum value or peak-to-peak value, are extracted and compared with the matched common-mode interference judgment threshold. If the amplitude does not exceed the standard, it is directly judged as qualified. If the amplitude exceeds the standard, it is further combined with the subsequent waveform correlation analysis logic for comprehensive judgment. Finally, a binary conclusion is output that characterizes whether the electromagnetic compatibility performance of the charger under test meets the design requirements under the current dynamic load conditions, namely the common-mode interference result.

[0111] In one embodiment, such as Figure 7 As shown, in step S53, which is the step of determining the common-mode interference result of the charger under test based on the net interference data and the common-mode interference determination threshold, the specific steps include:

[0112] S531, Monitor the amplitude of net interference data.

[0113] Specifically, the time series of the net interference data after differential noise reduction is traversed, and the peak search algorithm is used to identify the maximum absolute value of the voltage within the entire preset time window or to calculate the peak-to-peak value of the signal. This value is used as a quantitative indicator to characterize the current interference signal strength.

[0114] S532. If the amplitude values ​​are all below the common-mode interference judgment threshold, then the common-mode interference result is determined to be qualified.

[0115] Specifically, the quantized amplitude index obtained in step S531 is compared with the common-mode interference judgment threshold obtained in step S52. If the amplitude of all data points in the entire test window is strictly less than the threshold, it indicates that the output noise of the charger under test under dynamic load is completely within the allowable safety margin. At this time, there is no need to start a complex waveform feature analysis algorithm. The status flag bit indicating that the test has passed is directly generated, that is, the common-mode interference result is determined to be qualified.

[0116] S533. If there is an amplitude higher than the common-mode interference judgment threshold, calculate the autocorrelation coefficient of the net interference data within the preset time period and determine whether the autocorrelation coefficient meets the preset similarity condition.

[0117] Specifically, when the amplitude index is detected to exceed the judgment threshold, it indicates that there is potential excessive interference. At this time, a discrete sequence before and after the highest amplitude point in the net interference data is extracted as a sample. The theoretical switching period is calculated according to the center frequency parameter determined in step S43 and converted into the sampling point hysteresis. The cross-correlation degree between the sample sequence and its hysteresis sequence is calculated using the normalized discrete autocorrelation formula to obtain the autocorrelation coefficient with a value between 0 and 1. Then, the coefficient is compared with a preset similarity threshold, such as 0.85, to determine whether the excessive signal belongs to the inherent noise of the switching power supply with periodic characteristics or to an occasional non-periodic random pulse.

[0118] More specifically, based on the determined center frequency parameter f c Calculate the theoretical switching period T=1 / f c Convert this time period into the number of sampling points k, i.e., k = T × F s , where F s The sampling rate is used to obtain a discrete sequence x[n] containing N sampling points from the net interference data, where n = 0, 1, ..., N-1. This sequence is usually selected from the data segment before and after the point with the highest amplitude. The correlation coefficient at lag k points is calculated using the discrete autocorrelation formula. The calculation expression is:

[0119] Where x[n] is the voltage value of the original sequence at time n, and x[n+k] is the voltage value of the original sequence after shifting it backward by k sampling points. The numerator represents the inner product of the cross-correlation between the original sequence and the lagged sequence, and the denominator is the energy normalization factor used to ensure the results. The value range is between -1 and 1.

[0120] S534. If the autocorrelation coefficient meets the preset similarity condition, then the common mode interference result is determined to be unqualified.

[0121] Specifically, if the calculated autocorrelation coefficient is greater than the preset similarity threshold, for example... A value >0.85 indicates that the current out-of-range signal maintains extremely high waveform similarity even after a delay of one switching cycle, exhibiting significant periodicity and repetition on the time axis. This is entirely consistent with the essential characteristics of common-mode interference in switching power supplies. Therefore, it is confirmed that the signal is a real interference continuously generated by the internal circuit of the charger. It is determined that the electromagnetic compatibility performance of the product under the current operating conditions does not meet the design requirements, and the common-mode interference result is determined to be unqualified.

[0122] S535. If the autocorrelation coefficient does not meet the preset similarity condition, the common mode interference result is determined to be qualified.

[0123] Specifically, if the calculated autocorrelation coefficient is less than or equal to a preset similarity threshold, for example... ≤0.85 indicates that although the current out-of-range signal has a large amplitude, it lacks periodic repetition characteristics in time and belongs to a single transient event, such as voltage overshoot caused by the instantaneous switching of electronic load or spark interference caused by the operation of the test fixture relay. Such signals are not a continuous common-mode noise defect of the charger itself, so they are identified as false positive interference and ignored. Finally, the common-mode interference result is determined to be qualified.

[0124] In one embodiment, such as Figure 8 As shown, after step S40 and the step of determining the target common-mode interference signal, the charger common-mode interference detection method further includes:

[0125] S401. Obtain the physical parameters of the cable in the current test link.

[0126] Specifically, by using the parameters input by the user before testing, the physical attribute data of the signal transmission cable used by the current test fixture is obtained, such as the specific length of the cable (e.g., 1.5 meters), conductor material, wire diameter, and shielding type. These physical parameters together determine the signal attenuation characteristics of the cable at different frequencies, and their role is to provide a key index basis for accurately matching the compensation coefficient from the attenuation model database.

[0127] S402. Based on the center frequency parameter and the cable physical parameter, match the dynamic attenuation compensation coefficient corresponding to the frequency at each time point in the preset frequency attenuation mapping table.

[0128] Specifically, the cable frequency attenuation database, which has been measured and stored in advance by devices such as network analyzers, is invoked. For the frequency value at each time point in the frequency change sequence generated in step S432, combined with the physical parameters such as cable length obtained in step S401, interpolation or lookup operations are performed in the multidimensional mapping table to match the signal attenuation when the specific frequency is transmitted on the specific cable. This generates a dynamic attenuation compensation coefficient sequence with the same length as the center frequency parameter sequence and corresponding to each time point. This sequence reflects the loss degree of the target common-mode interference signal due to frequency drift during transmission.

[0129] S403. Dynamic amplitude correction of the target common-mode interference signal is performed using a dynamic attenuation compensation coefficient.

[0130] Specifically, a point-by-point amplitude correction operation based on time series is performed. The amplitude of the target common-mode interference signal at each sampling point is multiplied by the reciprocal of the dynamic attenuation compensation coefficient at the corresponding time, or the signal amplitude and the compensation coefficient value are added in the logarithmic domain. The signal energy lost due to cable transmission is replenished to the signal according to the frequency dependence, thereby restoring the true interference signal amplitude at the output port of the charger under test at the digital level. This effectively eliminates the problem of underestimation of the measured value caused by excessively long test cables or increased interference frequency, ensuring the accuracy and reliability of the final judgment result.

[0131] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0132] In one embodiment, an electronic device is provided, which may be a server, and its internal structure diagram may be as follows: Figure 9 As shown, this electronic device includes a processor, memory, network interface, and database connected via a system bus. The processor provides computing and control capabilities. The memory includes a non-volatile storage medium and internal memory. The non-volatile storage medium stores the operating system, computer programs, and database. The internal memory provides an environment for the operation of the operating system and computer programs in the non-volatile storage medium. The database stores data such as background noise spectrum data and response voltage signals. The network interface communicates with external terminals via a network connection. When the computer program is executed by the processor, it implements a charger common-mode interference detection method.

[0133] In one embodiment, an electronic device is provided, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to perform the following steps:

[0134] Get the preset load switching mode and the corresponding load switching conditions;

[0135] The charger under test is tested with initialization parameters to obtain the voltage signal output by the charger under test, and the background noise spectrum data is determined based on the voltage signal.

[0136] The load transition test is performed on the charger under test based on the preset load transition mode, and the response voltage signal of the charger under test within the preset time window is obtained.

[0137] Based on the response voltage signal, determine the center frequency parameter, and based on the center frequency parameter, determine the target common-mode interference signal;

[0138] Based on the load transition condition, the common-mode interference result of the charger under test is determined according to the target common-mode interference signal and background noise spectrum data.

[0139] In one embodiment, a computer-readable storage medium is provided having a computer program stored thereon, the computer program performing the following steps when executed by a processor:

[0140] Get the preset load switching mode and the corresponding load switching conditions;

[0141] The charger under test is tested with initialization parameters to obtain the voltage signal output by the charger under test, and the background noise spectrum data is determined based on the voltage signal.

[0142] The load transition test is performed on the charger under test based on the preset load transition mode, and the response voltage signal of the charger under test within the preset time window is obtained.

[0143] Based on the response voltage signal, determine the center frequency parameter, and based on the center frequency parameter, determine the target common-mode interference signal;

[0144] Based on the load transition condition, the common-mode interference result of the charger under test is determined according to the target common-mode interference signal and background noise spectrum data.

[0145] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. Any references to memory, storage, databases, or other media used in the embodiments provided in this application can include non-volatile and / or volatile memory. Non-volatile memory can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memory can include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in various forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), dual data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), Rambus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM), etc.

[0146] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the above-described division of functional units and modules is used as an example. In practical applications, the above functions can be assigned to different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above.

[0147] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A method for detecting common-mode interference in a charger, characterized in that, The common-mode interference detection method for the charger includes: Obtain a preset load switching mode and the corresponding load switching conditions. The load switching mode is used to characterize the trend type of load change, and the load switching conditions include the starting current value, the ending current value, the current change slope, and the duration of the switching action. The charger under test is tested with initialization parameters to obtain the voltage signal output by the charger under test, and the background noise spectrum data is determined based on the voltage signal. Based on the preset load switching mode, the charger under test is subjected to load switching test to obtain the response voltage signal of the charger under test within a preset time window. Based on the response voltage signal, determine the center frequency parameter, and based on the center frequency parameter, determine the target common-mode interference signal; Based on the load switching condition, the common-mode interference result of the charger under test is determined according to the target common-mode interference signal and the background noise spectrum data. The step of determining the center frequency parameter based on the response voltage signal specifically includes: The response voltage signal is fitted using a fitting algorithm to obtain the voltage baseline corresponding to the response voltage signal; The difference between the response voltage signal and the voltage baseline is calculated to obtain the high-frequency response signal; Perform time-frequency domain analysis on the high-frequency response signal to determine the center frequency parameter; The step of performing time-frequency domain analysis on the high-frequency response signal to determine the center frequency parameter specifically includes: The high-frequency response signal is transformed using a time-frequency transformation method to obtain a time-frequency distribution matrix; Within the time-frequency distribution matrix, a frequency variation sequence distributed over time is generated based on the frequency point corresponding to the maximum energy amplitude, and the frequency variation sequence is determined as the center frequency parameter.

2. The charger common-mode interference detection method according to claim 1, characterized in that, The step of determining the target common-mode interference signal based on the center frequency parameter specifically includes: A digital bandpass filter is constructed, wherein the center frequency of the digital bandpass filter is adjusted according to the center frequency parameter, and the passband width of the digital bandpass filter is a preset fixed value; The high-frequency response signal is input into the digital bandpass filter for filtering to obtain the target common-mode interference signal.

3. The charger common-mode interference detection method according to claim 1, characterized in that, The step of determining the common-mode interference result of the charger under test based on the load switching condition, the target common-mode interference signal, and the background noise spectrum data specifically includes: Obtain the signal spectrum data of the target common-mode interference signal, calculate the difference between the signal spectrum data and the background noise spectrum data, and determine the net interference data; Based on the load transition conditions, the corresponding common-mode interference determination threshold is obtained; Based on the net interference data and the common-mode interference determination threshold, the common-mode interference result of the charger under test is determined.

4. The charger common-mode interference detection method according to claim 3, characterized in that, The step of determining the common-mode interference result of the charger under test based on the net interference data and the common-mode interference determination threshold specifically includes: Monitor the amplitude of the net interference data; If all of the amplitude values ​​are below the common-mode interference determination threshold, then the common-mode interference result is determined to be qualified. If the amplitude is higher than the common-mode interference determination threshold, the autocorrelation coefficient of the net interference data within a preset time period is calculated, and it is determined whether the autocorrelation coefficient meets the preset similarity condition. If the autocorrelation coefficient satisfies the preset similarity condition, then the common-mode interference result is determined to be unqualified; If the autocorrelation coefficient does not meet the preset similarity condition, then the common-mode interference result is determined to be qualified.

5. The charger common-mode interference detection method according to claim 1, characterized in that, Following the step of determining the target common-mode interference signal, the charger common-mode interference detection method further includes: Obtain the physical parameters of the cable in the current test link; Based on the center frequency parameter and the cable physical parameter, a dynamic attenuation compensation coefficient corresponding to the frequency at each time point is matched in a preset frequency attenuation mapping table. The target common-mode interference signal is dynamically amplitude corrected using the dynamic attenuation compensation coefficient.

6. A common-mode interference detection system for chargers, characterized in that, The charger common-mode interference detection system includes: The hardware link unit includes an AC power input interface, an isolation transformer, an EMI power frequency filter, a fixture switching module, and an oscilloscope connected sequentially along the signal transmission direction. The control terminal is communicatively connected to the fixture switching module and the oscilloscope, and is used to execute the charger common-mode interference detection method as described in any one of claims 1 to 5.

7. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the steps of the method as described in any one of claims 1 to 5.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the steps of the method as described in any one of claims 1 to 5.

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