Power module capacitor capacitance estimation method, device, medium and apparatus

Abstract

The power module capacitor capacity estimation method, device, medium and equipment provided by the application calculate the reference voltages of the capacitor voltage sequence in the stable section and the calibration section respectively, establish references in the stable section and the calibration section respectively, determine the reference drift amount, and dynamically correct the original voltage change value based on this to obtain a more accurate target voltage change value. At the same time, the segmented weighted integration is introduced in the processing of the bridge arm current sequence, the current weighted integration is calculated according to the different dynamic characteristics of the transition section and the input stable section, the current integration can more truly reflect the actual energy storage change of the capacitor, and the accuracy of the target current value is further ensured. Finally, the capacity is calculated by using the two optimized key physical quantities, so that the result is closer to the actual state of the capacitor. In this process, through the structured signal segmentation and dynamic correction strategy, the real-time response capability of the capacity estimation method is enhanced while ensuring high estimation accuracy.

Description

Technical Field

[0001] This application relates to the field of power electronics technology, and in particular to a method, apparatus, dielectric and equipment for estimating the capacitance value of a power module capacitor. Background Technology

[0002] Modular multilevel converters (MMCs) are core equipment in high-voltage direct current (HVDC) transmission and new energy grid integration. Their high reliability and superior power quality depend heavily on the normal operation of their submodules. Capacitors within these submodules are critical energy storage components, and their capacitance is prone to decline due to aging during long-term operation. Significant capacitance degradation directly impacts the energy storage performance of the submodule and can even trigger system failures. Therefore, real-time and accurate monitoring and estimation of capacitor capacitance values ​​are of paramount importance.

[0003] Currently, capacitor capacitance estimation methods are mainly divided into two categories: model-based and signal processing-based approaches. The former establishes a voltage model for a submodule and uses adaptive algorithms to estimate the capacitor voltage, thereby calculating the capacitance value. However, this method relies on a precise mathematical model and has stringent requirements for parameter accuracy. The latter directly calculates the capacitance value based on the capacitor's current and voltage sampling signals and uses filtering algorithms to suppress noise interference. However, this approach still has shortcomings. On the one hand, the noise filtering algorithms used are often complex and difficult to meet the requirements of real-time processing capabilities. On the other hand, the capacitance calculation formula is relatively uniform, and the matching degree between voltage change and current integral is insufficient, affecting the accuracy of the estimation results.

[0004] In summary, existing capacitor capacitance estimation methods are insufficient to meet the requirements of real-time performance and accuracy. Summary of the Invention

[0005] The purpose of this application is to at least address one of the aforementioned technical deficiencies, particularly the technical deficiency that existing capacitor capacitance estimation methods are unable to meet the requirements of real-time performance and accuracy.

[0006] In a first aspect, this application provides a method for estimating the capacitance value of a power module capacitor, the method comprising:

[0007] The arm current sequence and capacitor voltage sequence of the power module under test are acquired over a period of time, and the target switching stage is determined within this period of time; the target switching stage includes a stable section, a transition section, a stable input section, and a calibration section.

[0008] Calculate the reference voltages of the capacitor voltage sequence in the stable segment and the calibration segment respectively to obtain the reference voltage of the stable segment and the reference voltage of the calibration segment;

[0009] The original voltage change value of the power module under test before and after the target switching stage is determined, and the original voltage change value is corrected based on the stable section reference voltage and the calibration section reference voltage to obtain the target voltage change value;

[0010] The target current value is determined by calculating the current-weighted integral of the bridge arm current sequence in the transition section and the stabilization section, respectively.

[0011] Based on the target voltage change value and the target current value, determine the capacitor value of the power module under test at the current moment.

[0012] In one embodiment, acquiring the bridge arm current sequence and capacitor voltage sequence of the power module under test over a period of time includes:

[0013] Collect bridge arm current data and capacitor voltage sequence of the power module under test over a period of time;

[0014] The bridge arm current data is subjected to forward Newton interpolation to make the processed bridge arm current data match the sampling frequency of the capacitor voltage sequence.

[0015] Based on the processed arm current data, an arm current sequence is generated.

[0016] In one embodiment, the step of calculating the reference voltages of the capacitor voltage sequence in the stable segment and the calibration segment, respectively, to obtain the stable segment reference voltage and the calibration segment reference voltage, includes:

[0017] Extract the first voltage sequence of the capacitor voltage sequence in the stable segment, and calculate the average value of the first voltage sequence to obtain the reference voltage of the stable segment;

[0018] Extract the second voltage sequence of the capacitor voltage sequence in the calibration segment, and calculate the average value of the second voltage sequence to obtain the reference voltage of the calibration segment.

[0019] In one embodiment, determining the original voltage change value of the power module under test before and after the target switching phase includes:

[0020] Determine the end point of the stable segment of the target deployment phase and the end point of the stable segment;

[0021] The original voltage change value is obtained by subtracting the voltage value corresponding to the end point of the stable segment from the voltage value corresponding to the end point of the stable segment in the capacitor voltage sequence.

[0022] In one embodiment, the step of correcting the original voltage change value based on the stable segment reference voltage and the calibration segment reference voltage to obtain the target voltage change value includes:

[0023] Calculate the absolute value of the difference between the calibration section reference voltage and the stable section reference voltage;

[0024] If the absolute value is not greater than a preset threshold, the difference between the calibration segment reference voltage and the stable segment reference voltage is determined as the voltage correction value; otherwise, the historical average reference of the stable segment and the historical average reference of the calibration segment are obtained, and the difference between the historical average reference of the calibration segment and the historical average reference of the stable segment is determined as the voltage correction value.

[0025] Once the voltage correction value is determined, the original voltage change value is corrected based on the voltage correction value to obtain the corrected voltage change value. The proportion of the voltage change in the stable segment to the sum of the transition segment and the stable segment is determined. Based on this proportion, the corrected voltage change value is corrected a second time to obtain the target voltage change value.

[0026] In one embodiment, calculating the current-weighted integral of the bridge arm current sequence in the transition section and the stabilization section respectively to determine the target current value includes:

[0027] Obtain the current compensation coefficient of the transition section and the current compensation coefficient of the stabilization section, and extract the first current sequence of the bridge arm current sequence in the transition section and the second current sequence in the stabilization section.

[0028] Integrating the first current sequence and the second current sequence yields a first current integral and a second current integral. Using the current compensation coefficient of the transition section and the current compensation coefficient of the stabilization section, the first current integral and the second current integral are weighted and summed to obtain the target current value.

[0029] In one embodiment, determining the capacitor value of the power module under test at the current moment based on the target voltage change value and the target current value includes:

[0030] Calculate the quotient of the target current value and the target voltage change value, and determine the calculation result as the preliminary capacitor capacitance value;

[0031] Obtain the capacitor values ​​of the previous N time steps at the current time step, and perform a moving average filtering process on the preliminary capacitor value based on the capacitor values ​​of the previous N time steps to obtain the capacitor value of the power module under test at the current time step.

[0032] Secondly, this application provides a power module capacitor value estimation device, the device comprising:

[0033] The data acquisition module is used to acquire the arm current sequence and capacitor voltage sequence of the power module under test over a period of time, and to determine the target switching stage within that period of time; the target switching stage includes a stabilization stage, a transition stage, a stabilization stage, and a calibration stage.

[0034] The voltage calculation module is used to calculate the reference voltages of the capacitor voltage sequence in the stable segment and the calibration segment, respectively, to obtain the reference voltage of the stable segment and the reference voltage of the calibration segment;

[0035] The voltage correction module is used to determine the original voltage change value of the power module under test before and after the target switching stage, and correct the original voltage change value based on the stable section reference voltage and the calibration section reference voltage to obtain the target voltage change value.

[0036] The current calculation module is used to calculate the current-weighted integral of the bridge arm current sequence in the transition section and the stable input section, respectively, to determine the target current value;

[0037] The capacitance value determination module is used to determine the capacitance value of the capacitor of the power module under test at the current moment based on the target voltage change value and the target current value.

[0038] Thirdly, this application provides a storage medium storing computer-readable instructions that, when executed by one or more processors, cause the one or more processors to perform the steps of the power module capacitor value estimation method as described in any of the above embodiments.

[0039] Fourthly, this application provides a computer device, including: one or more processors, and a memory;

[0040] The memory stores computer-readable instructions, and when the one or more processors execute the computer-readable instructions, they perform the steps of the power module capacitor value estimation method as described in any of the above embodiments.

[0041] As can be seen from the above technical solutions, the embodiments of this application have the following advantages:

[0042] The power module capacitor capacitance estimation method, apparatus, dielectric, and equipment provided in this application acquire the bridge arm current sequence and capacitor voltage sequence of the power module under test over a period of time, determine the target switching stage within that time period, and then calculate the reference voltage of the capacitor voltage sequence in the stable and calibration stages respectively. References are established in both the stable and calibration stages to determine the reference drift, and the original voltage change value is dynamically corrected based on this to obtain a more accurate target voltage change value. Simultaneously, a piecewise weighted integral is introduced in the processing of the bridge arm current sequence. The current weighted integral is calculated separately according to the different dynamic characteristics of the transition stage and the stable stage. Energy loss at different stages is compensated by coefficient weighting, making the current integral more accurately reflect the actual energy storage change of the capacitor, further ensuring the accuracy of the target current value. Finally, the capacitance value is calculated using these two optimized key physical quantities, making the result closer to the actual state of the capacitor. In this process, through structured signal segmentation and dynamic correction strategies, the influence of noise and measurement errors can be effectively suppressed without over-reliance on complex filtering algorithms, while significantly reducing computational complexity. This ensures high estimation accuracy and enhances the real-time response capability of the capacitance estimation method. Attached Figure Description

[0043] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0044] Figure 1 A flowchart illustrating a method for estimating the capacitance value of a power module capacitor provided in an embodiment of this application;

[0045] Figure 2 A schematic diagram illustrating the process of correcting the original voltage change value based on the stable section reference voltage and the calibration section reference voltage, provided for embodiments of this application;

[0046] Figure 3 This is a schematic diagram of a power module capacitor capacitance estimation device provided in an embodiment of this application;

[0047] Figure 4 This is an internal structural diagram of a computer device provided in an embodiment of this application. Detailed Implementation

[0048] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0049] In one embodiment, this application provides a method for estimating the capacitance value of a power module capacitor. The following embodiments illustrate the application of this method to a server. It is understood that the power module capacitor capacitance value estimation method can be performed by a single server or by a server cluster consisting of multiple servers, and this application does not impose any specific limitations on this.

[0050] like Figure 1 As shown, this application provides a method for estimating the capacitance value of a power module capacitor, the method comprising:

[0051] S101: Obtain the bridge arm current sequence and capacitor voltage sequence of the power module under test over a period of time, and determine the target switching stage within that period of time.

[0052] The target switching phase includes a stabilization phase, a transition phase, a stabilization phase, and a calibration phase. The power under test (DUT) module refers to the sub-module in a modular multilevel converter that requires capacitor capacitance estimation. This sub-module typically contains key components such as IGBTs (Insulated Gate Bipolar Transistors) and capacitors, and is the smallest power unit constituting the converter. The arm current sequence refers to a set of ordered data obtained by sampling the current flowing through the arm containing the DUT module over time before and after the DUT module is switched on. The capacitor voltage sequence refers to a set of ordered data obtained by sampling the voltage across the capacitors in the DUT module before and after the DUT module is switched on.

[0053] In this step, when the server receives the capacitance estimation command, it can acquire the arm current sequence and capacitor voltage sequence of the power module under test (DUT) over a period of time. Specifically, the arm current sequence and capacitor voltage sequence of the DUT can be determined by periodically acquiring valve-controlled communication data. Furthermore, current and voltage sensors are installed on the DUT to collect and record the current signal of the arm containing the DUT and the voltage signal of the capacitor within the DUT, forming valve-controlled communication data.

[0054] Specifically, after collecting the bridge arm current sequence and capacitor voltage sequence over a period of time, a complete switching phase of the power module under test (DUT) can be determined within that time period, i.e., the target switching phase. When multiple complete switching phases exist, one can be randomly selected as the target switching phase, or the switching phase closest to the current time can be selected as the target switching phase. This application does not impose specific limitations on this. Furthermore, the time ranges of the stable segment, transition segment, stable input segment, and calibration segment within that period can be determined by identifying the transition edge of the trigger pulse signal of the DUT. The trigger pulse signal refers to the digital control signal used to control the on and off states of switching devices such as insulated-gate bipolar transistors (IGBTs) in the DUT. For example, a high level indicates input, connecting the capacitor to the bridge arm circuit, while a low level indicates de-input, bypassing the capacitor from the bridge arm circuit.

[0055] For example, during normal modulation operation of the converter, current signals are collected using current sensors (such as Hall sensors) installed on the bridge arm, and the voltage of the submodule capacitor is measured through a voltage sampling circuit. The analog quantity is converted into a digital sequence at a fixed sampling frequency, thereby obtaining the bridge arm current sequence and capacitor voltage sequence.

[0056] S102: Calculate the reference voltages of the capacitor voltage sequence in the stable segment and the calibration segment respectively, and obtain the reference voltages of the stable segment and the calibration segment.

[0057] The stable phase refers to the period during which the power module under test (DUT) is in an off-state and the capacitor voltage remains relatively stable. The calibration phase refers to the period during which the capacitor voltage returns to a relatively stable state after the DUT has been switched on and off once. The trigger pulse signal for the DUT is 0 during both phases. The stable phase reference voltage is a voltage reference value obtained through statistical analysis of the capacitor voltage sequence within the stable phase. The calibration phase reference voltage is a voltage reference value obtained through statistical analysis of the capacitor voltage sequence within the calibration phase.

[0058] In this step, the time intervals for the stable and calibration sections are determined based on the operating state of the power module under test (e.g., trigger pulse signal). For example, within the stable section, the capacitor voltage is relatively stable. The sampled capacitor voltage values ​​within this stable section are determined based on the capacitor voltage sequence, and the average value of these sampled values ​​is calculated as the stable section reference voltage. Similarly, within the calibration section, the sampled capacitor voltage values ​​are determined based on the capacitor voltage sequence, and the average value of these sampled values ​​is calculated as the calibration section reference voltage. In this way, two reference voltage values ​​can be accurately obtained: the stable section reference voltage represents the initial stable level of the capacitor voltage before activation, and the calibration section reference voltage represents the new steady-state level to which the capacitor voltage recovers after activation and deactivation. These two reference voltages provide precise start and end point references for subsequent calculations of voltage variation differences, forming a set of comparable dual reference voltages for monitoring and correcting voltage reference point drift.

[0059] Specifically, within the stable segment and the calibration segment, the corresponding voltage sequence is extracted from the capacitor voltage sequence, and the arithmetic mean of all sampling points within the sequence is calculated as the reference voltage for that segment.

[0060] S103: Determine the original voltage change value of the power module under test before and after the target switching stage, and correct the original voltage change value based on the reference voltage of the stable section and the reference voltage of the calibration section to obtain the target voltage change value.

[0061] In this step, the server locates a point where the voltage was stable before switching on (e.g., the last sampling point of the stable phase) and a point where the voltage stabilized again after switching on (e.g., the first sampling point of the calibration phase) based on the transition edge of the trigger pulse signal of the power module under test during the target switching phase. The server then subtracts the corresponding voltage values ​​in the capacitor voltage sequence to obtain the original voltage change value. Next, a correction phase is initiated. Specifically, in the correction phase, the difference between the calibration phase reference voltage and the stable phase reference voltage is calculated. This difference represents the slow drift of the voltage reference from the beginning to the end of the operating cycle. In other words, subtracting this reference drift from the original voltage change value eliminates voltage drift interference. Further, noise components caused by voltage instability during the transition phase can be removed, ultimately outputting a target voltage change value that represents the true voltage change.

[0062] For example, if the reference drift is +2V (the reference voltage in the calibration section is 2V higher than the reference voltage in the stable section), then when calculating the final effective voltage change, this slow 2V rise can be subtracted from the original voltage change to avoid overestimating the actual energy storage change of the capacitor.

[0063] Furthermore, the raw voltage change value refers to the voltage difference obtained by directly subtracting the instantaneous sampled values ​​of the capacitor voltage before and after the moment the power module under test is activated. It initially reflects the amplitude of voltage change across the capacitor throughout the entire operating cycle, but includes errors caused by non-ideal factors. The target voltage change value, on the other hand, is the difference obtained after systematically correcting the raw voltage change value based on the stable section reference voltage and the calibration section reference voltage (e.g., deducting voltage drift and eliminating unstable components in the transition section), and is a more representative representation of the true effective voltage change of the capacitor during charging and discharging.

[0064] S104: Calculate the current-weighted integral of the bridge arm current sequence in the transition section and the stable section respectively to determine the target current value.

[0065] The transition phase refers to the brief dynamic process after the trigger pulse signal of the power module under test (DUT) changes direction, during which the capacitor voltage has not yet reached a stable state due to factors such as the switching process and parasitic parameters in the circuit. The stable input phase refers to the continuous process after the DUT completes the input action, during which the trigger pulse signal remains valid, and the capacitor voltage has stabilized and entered a steady-state charging or discharging phase. The target current value refers to the equivalent current value of the actual charge or discharge during the entire input period.

[0066] In this step, the time intervals for the transition and stabilization phases are determined based on the operating status of the power module under test (e.g., trigger pulse signal). Then, the current sequences corresponding to the transition and stabilization phases are divided from the continuous bridge arm current sequence. Next, different weighting coefficients are applied to the current sequences belonging to different time periods for integration to compensate for energy losses at different stages and obtain a target current value that is closer to reality.

[0067] Specifically, during the transition phase, the current sequence in this interval is integrated and multiplied by a weighting factor less than 1. This factor compensates for the charge loss actually flowing into the capacitor caused by IGBT switching losses and parasitic oscillations in the circuit during this phase. Then, during the stabilization phase, the current sequence in this interval is similarly integrated and multiplied by a corresponding weighting factor based on the current direction (charging or discharging) to compensate for the energy loss caused by the equivalent series resistance of the capacitor during this phase. Finally, the results of the two segmented weighted integrations are summed to obtain the target current value.

[0068] For example, in a modular multilevel converter, the current sampling value of a submodule in the transition section is 10A, and the current sampling value in the stabilization section is 5A. Through weighted integration, the weighted integral value of the current in the transition section is 9.95A, and the weighted integral value of the current in the stabilization section is 5.15A. Finally, these two weighted integral values ​​are added together to obtain the target current value of 15.1A.

[0069] S105: Determine the capacitance value of the capacitor of the power module under test at the current moment based on the target voltage change value and the target current value.

[0070] In this step, the target voltage change and target current value reflect the actual change in capacitor voltage and the actual contribution of current, respectively. Once the target voltage change and target current values ​​are determined, the capacitance value of the power module under test at the current moment can be calculated using the basic formula for capacitance.

[0071] It is understandable that the corrected target voltage change value can more accurately reflect the true change in capacitor voltage, and the target current value, calculated through piecewise weighted integration, can more accurately reflect the charging and discharging amount of the capacitor. Combining these two precisely processed values ​​and calculating the capacitance value using the basic capacitance formula can improve the accuracy and reliability of capacitance value estimation. This process not only considers the dynamic characteristics of voltage and current changes but also eliminates the influence of non-ideal factors through correction and compensation mechanisms, thereby ensuring high accuracy and stability of capacitance value estimation, as well as the stable operation of the modular multilevel converter.

[0072] In the above embodiment, the arm current sequence and capacitor voltage sequence of the power module under test are acquired over a period of time, and the target switching stage is determined within this period. Then, the reference voltage of the capacitor voltage sequence in the stable and calibration stages is calculated separately. References are established in both the stable and calibration stages to determine the reference drift. Based on this, the original voltage change value is dynamically corrected to obtain a more accurate target voltage change value. Simultaneously, a piecewise weighted integral is introduced in the processing of the arm current sequence. The current weighted integral is calculated according to the different dynamic characteristics of the transition and stable stages. Energy loss at different stages is compensated by coefficient weighting, making the current integral more accurately reflect the actual energy storage change of the capacitor, further ensuring the accuracy of the target current value. Finally, the capacitance value is calculated using these two optimized key physical quantities, making the result closer to the actual state of the capacitor. In this process, through structured signal segmentation and dynamic correction strategies, without overly relying on complex filtering algorithms, the influence of noise and measurement errors is effectively suppressed, and the computational complexity is significantly reduced. This ensures high estimation accuracy while enhancing the real-time response capability of the capacitance estimation method.

[0073] In one embodiment, acquiring the bridge arm current sequence and capacitor voltage sequence of the power module under test over a period of time includes:

[0074] S1: Collect the bridge arm current data and capacitor voltage sequence of the power module under test over a period of time.

[0075] S2: Perform forward Newton interpolation on the bridge arm current data to match the sampling frequency of the capacitor voltage sequence.

[0076] S3: Generate a bridge arm current sequence based on the processed bridge arm current data.

[0077] In this embodiment, when determining the bridge arm current data and capacitor voltage sequence of the power module under test over a period of time, the sampling frequency of the capacitor voltage signal is high because it is synchronized with the IGBT trigger pulse period. However, the sampling frequency of the bridge arm current signal is slower, typically 50μs, and is not synchronized with the capacitor voltage sampling period. To avoid calculation errors caused by the asynchrony of voltage and current signals, and considering that the IGBT trigger pulse signal cannot be processed by linear interpolation and the bridge arm current cannot change abruptly, linear interpolation can be performed on the bridge arm current data. For example, forward Newton interpolation. Forward Newton interpolation is a mathematical interpolation method that constructs a polynomial for known discrete data points, thereby inserting new data points at arbitrary positions to match the sampling frequency of the processed bridge arm current data with the capacitor voltage sequence.

[0078] In one example, assume the interpolation point is ,in The original data sampling period, This is the ratio of the interpolated sampling period to the original sampling period. This is achieved through forward selection. Constructing from consecutive sampled data The bridge arm current data at time t, after interpolation, is represented by the second-order Newton polynomial as follows:

[0079]

[0080] in The order difference is expressed as:

[0081]

[0082] The interpolated bridge arm current data is defined as follows: , This represents the i-th current sample value in the bridge arm current data.

[0083] Specifically, when collecting bridge arm current data and capacitor voltage sequences of the power module under test over a period of time, the data can be directly acquired through sensors installed on the power module under test, or it can be obtained from valve-controlled communication data generated periodically. This application does not impose specific limitations on this.

[0084] In one embodiment, the reference voltages of the capacitor voltage sequence in the stable segment and the calibration segment are calculated respectively to obtain the reference voltage in the stable segment and the reference voltage in the calibration segment, including:

[0085] S1: Extract the first voltage sequence of the capacitor voltage sequence in the stable segment, and calculate the average value of the first voltage sequence to obtain the reference voltage of the stable segment.

[0086] S2: Extract the second voltage sequence of the capacitor voltage sequence in the calibration segment, and calculate the average value of the second voltage sequence to obtain the reference voltage of the calibration segment.

[0087] In this embodiment, the first voltage sequence of the capacitor voltage sequence in the stable segment is extracted, and its average value is calculated to obtain the reference voltage for the stable segment. Similarly, the second voltage sequence of the capacitor voltage sequence in the calibration segment is extracted, and its average value is calculated to obtain the reference voltage for the calibration segment. These reference voltages are calculated by averaging the sampled capacitor voltage values ​​over the corresponding time periods. It can be understood that by calculating the average voltage of these two stages separately as a reference, and subsequently using it to correct voltage changes, a dynamic "dual reference point" is established for the entire observation window. This effectively quantifies and subtracts slow voltage changes (i.e., reference drift) caused by factors such as sensor bias drift, ambient temperature changes, or circuit leakage, thereby improving the accuracy of capacitor capacitance estimation.

[0088] Specifically, the operating phases divided based on the trigger pulse signal can be represented as: stable phase (t0~t1, ), transition section (t1~t2, From 0 to 1), entering the stable phase (t2~t3, ), calibration segment (t3~t4, ).in This indicates a trigger pulse signal.

[0089] In one example, the process of calculating the average value of the first voltage sequence to obtain the reference voltage for the stable segment, and calculating the average value of the second voltage sequence to obtain the reference voltage for the calibration segment, can be represented as follows:

[0090]

[0091]

[0092] In the formula, Indicates the reference voltage for the stable segment. This represents the total number of voltage samples within the stable segment, i.e., the length of the first voltage sequence. This represents the i-th voltage sample value in the first voltage sequence. Indicates the reference voltage for the calibration section. This represents the total number of voltage samples within the calibration interval, i.e., the length of the second voltage sequence. This represents the j-th voltage sample value in the second voltage sequence.

[0093] In one embodiment, determining the original voltage change of the power module under test before and after the target switching phase includes:

[0094] S1: Determine the end point of the stable phase of the target deployment phase and the end point of the stable phase.

[0095] S2: Subtract the voltage values ​​corresponding to the end point of the stable segment and the end point of the stable segment in the capacitor voltage sequence to obtain the original voltage change value.

[0096] In this embodiment, when the end points of the input and stabilization segments of the target switching phase are determined, the voltage values ​​corresponding to the end points of the stabilization and input segments are found in the capacitor voltage sequence, and the difference between these two voltage values ​​is calculated to obtain the original voltage change value. By subtracting the voltage values ​​corresponding to the end points of the input and stabilization segments in the capacitor voltage sequence, the original voltage change value can be directly obtained. This calculation method reflects the change in capacitor voltage before and after the power module under test is switched on, and also provides basic data for subsequent change value correction.

[0097] like Figure 2 As shown, in one embodiment, the original voltage change value is corrected based on the stable section reference voltage and the calibration section reference voltage to obtain the target voltage change value, including:

[0098] S201: Calculate the absolute value of the difference between the reference voltage of the calibration section and the reference voltage of the stable section.

[0099] S202: Determine whether the absolute value is greater than the preset threshold.

[0100] S203: If the absolute value is not greater than the preset threshold, the difference between the calibration section reference voltage and the stable section reference voltage is determined as the voltage correction value.

[0101] S204: If the absolute value is greater than the preset threshold, obtain the historical average reference of the stable segment and the historical average reference of the calibration segment, and determine the difference between the historical average reference of the calibration segment and the stable segment as the voltage correction value.

[0102] S205: After determining the voltage correction value, the original voltage change value is corrected based on the voltage correction value to obtain the corrected voltage change value. The proportion of the voltage change in the stable segment to the sum of the transition segment and the stable segment is determined. Based on this proportion, the corrected voltage change value is corrected a second time to obtain the target voltage change value.

[0103] The preset threshold is an empirical value and can be set to 0.3% of the capacitor's rated voltage.

[0104] In this embodiment, the absolute value of the difference between the calibration section reference voltage and the stable section reference voltage is calculated to assess whether the difference between the two reference voltages is within an acceptable range. If the absolute value is not greater than a preset threshold, it indicates that the current reference voltage difference is small, and the difference between the calibration section reference voltage and the stable section reference voltage can be directly determined as the voltage correction value. However, if the absolute value is greater than the preset threshold, it indicates that the current reference voltage may have a large deviation. In this case, historical data can be introduced for calibration, and the difference between the calibration section reference voltage and the historical average reference voltage of the stable section can be determined as the voltage correction value. This calibration method based on historical data can effectively reduce reference voltage deviations caused by sudden events or measurement errors.

[0105] Next, after determining the voltage correction value, the voltage correction value is subtracted from the original voltage change value to obtain the corrected voltage change value. Then, the proportion of the stable segment to the sum of the transition segment and the stable segment is determined, and this proportion is multiplied by the corrected voltage change value to eliminate invalid data from the transition segment, thus obtaining the target voltage change value.

[0106] Understandably, directly using the instantaneous voltage difference before and after switching on (the original voltage change value) inevitably introduces two key sources of error: first, the inherent slow drift of the voltage sensor or circuit during the non-switching period, which causes a shift in the voltage reference point; and second, unstable components such as voltage jitter caused by the switching action at the moment of switching on, which do not represent the steady-state energy storage change of the capacitor. Without correction, these errors will directly propagate to the capacitance calculation results, causing the estimated value to deviate from the true value. By introducing the average reference voltage of the stable and calibration sections, the voltage reference drift within the entire observation window can be accurately quantified and subtracted from the calculation. After obtaining the corrected voltage change value, by defining and eliminating invalid data in the transition section, non-steady-state interference can be further filtered out.

[0107] In one example, if Then, the historical average references for the stable segment and the calibration segment are obtained, and the difference between the historical average references for the calibration segment and the stable segment is determined as the voltage correction value. The difference between the calibration section reference voltage and the stable section reference voltage is then determined as the voltage correction value. This represents the capacitor's rated voltage. The original voltage change is then corrected using a voltage correction value to obtain the corrected voltage change value. This process can be represented as:

[0108]

[0109] In the formula, This indicates the corrected voltage change value. This represents the original voltage change value. Indicates the voltage correction value. Indicates the reference voltage for the calibration section. This represents the reference voltage for the stable segment.

[0110] After determining the corrected voltage change value, the data in the transition segment of the corrected voltage change value is removed to obtain the target voltage change value. This process can be expressed as:

[0111]

[0112] In the formula, Indicates the target voltage change value. This indicates the corrected voltage change value. This indicates the time corresponding to the end of the stable phase. This represents the time corresponding to the end of the transition phase / the time corresponding to the start of the stabilization phase. This indicates the time corresponding to the start point of the transition segment.

[0113] In one embodiment, the current-weighted integrals of the bridge arm current sequence during the transition and stabilization phases are calculated separately to determine the target current value, including:

[0114] S1: Obtain the current compensation coefficient of the transition section and the current compensation coefficient of the stable section, and extract the first current sequence of the bridge arm current sequence in the transition section and the second current sequence in the stable section.

[0115] S2: Integrate the first current sequence and the second current sequence to obtain the first current integral and the second current integral. Then, using the current compensation coefficient of the transition section and the current compensation coefficient of the stabilization section, perform a weighted summation of the first current integral and the second current integral to obtain the target current value.

[0116] The current compensation coefficient is used to compensate for current deviations caused by IGBT switching losses, capacitor equivalent series resistance losses, and other factors during the transition and stabilization phases. The current compensation coefficient for the transition phase can be set to 0.995, for the stabilization phase (charging) it can be set to 1.03, and for the stabilization phase (discharging) it can be set to 0.99.

[0117] In this embodiment, current compensation coefficients for the transition and stabilization phases are obtained. These coefficients are typically preset based on the operating state (such as charging or discharging) and actual operating conditions of the power module under test. For example, the current compensation coefficient for the transition phase can be used to compensate for IGBT switching losses, while the current compensation coefficient for the stabilization phase can be used to compensate for capacitor equivalent series resistance (ESR) losses. Simultaneously, the first current sequence in the transition phase and the second current sequence in the stabilization phase are extracted from the bridge arm current sequence. Then, the first and second current sequences are integrated respectively to obtain the first current integral and the second current integral. Then, using the current compensation coefficients for the transition and stabilization phases, the first and second current integrals are weighted and summed to obtain the target current value. The target current value obtained in this way not only considers the current variation characteristics at different stages but also eliminates the influence of non-ideal factors through the current compensation coefficients, thereby improving the estimation accuracy of the capacitor capacitance value calculated based on the target current value.

[0118] In one example, the process of weighted integration of the first current sequence of the transition section can be expressed as:

[0119]

[0120] In the formula, Represents the first current integral. This represents the current compensation coefficient for the transition section. ~ Indicates the entry into a stable phase. This represents the bridge arm current sequence.

[0121] When the stable phase is charging, the process of weighted integration of the second current sequence during the stable phase can be expressed as:

[0122]

[0123] When the stable phase is during discharge, the process of weighted integration of the second current sequence during the stable phase can be expressed as:

[0124]

[0125] In the formula, , This represents the second current integral. This indicates the current compensation coefficient during the stable charging phase. This represents the current compensation coefficient during the stable phase of discharge. ~ Indicates the entry into a stable phase. This represents the bridge arm current sequence.

[0126] Based on this, when the stable phase is charging, the target current value is... It can be represented as:

[0127]

[0128] When the stable phase is during discharge, the target current value can be expressed as:

[0129]

[0130] In one embodiment, determining the capacitor value of the power module under test at the current moment based on the target voltage change value and the target current value includes:

[0131] S1: Calculate the quotient of the target current value and the target voltage change value, and determine the calculation result as the preliminary capacitor value.

[0132] S2: Obtain the capacitor values ​​of the previous N time steps at the current time step, and perform a moving average filtering process on the initial capacitor values ​​based on the capacitor values ​​of the previous N time steps to obtain the capacitor value of the power module under test at the current time step.

[0133] Where N is a positive integer greater than 1.

[0134] In this embodiment, to further improve the accuracy and stability of the capacitance estimation when calculating the initial capacitor value, the capacitor values ​​of the previous N time points can be obtained. This historical capacitance data can be obtained by storing and retrieving previously calculated capacitor values. Then, a moving average filter is applied to the initial capacitor value based on the capacitance values ​​of the previous N time points. Moving average filtering is a commonly used signal processing method; by averaging the capacitance values ​​over N consecutive time points, noise and random fluctuations can be effectively filtered out, resulting in a smoother and more stable capacitance estimation.

[0135] In one example, the process of calculating the quotient of the target current value and the target voltage change value can be expressed as:

[0136]

[0137] In the formula, This indicates the initial capacitance value of the capacitor. Indicates the target current value. This represents the target voltage change value. Then, a moving average filtering algorithm is used to further process the initial capacitor capacitance value to filter out noise. This process can be represented as:

[0138]

[0139] In the formula, This indicates the capacitance value of the capacitor in the power module under test at the current moment. That is, N.

[0140] It should be understood that although the steps in the flowcharts of the embodiments described above are shown sequentially according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some steps in the flowcharts of the embodiments described above may include multiple steps or multiple stages. These steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these steps or stages is not necessarily sequential, but can be performed alternately or in turn with other steps or at least some of the steps or stages of other steps.

[0141] The following describes the power module capacitor value estimation device provided in the embodiments of this application. The power module capacitor value estimation device described below and the power module capacitor value estimation method described above can be referred to each other.

[0142] like Figure 3 As shown, this application provides a power module capacitor value estimation device 300, the device comprising:

[0143] The data acquisition module 301 is used to acquire the arm current sequence and capacitor voltage sequence of the power module under test over a period of time, and to determine the target switching stage within that period of time; the target switching stage includes a stable section, a transition section, a stable input section, and a calibration section.

[0144] The voltage calculation module 302 is used to calculate the reference voltage of the capacitor voltage sequence in the stable section and the calibration section respectively, so as to obtain the reference voltage of the stable section and the reference voltage of the calibration section.

[0145] The voltage correction module 303 is used to determine the original voltage change value of the power module under test before and after the target switching stage, and correct the original voltage change value based on the reference voltage of the stable section and the reference voltage of the calibration section to obtain the target voltage change value.

[0146] The current calculation module 304 is used to calculate the current-weighted integral of the bridge arm current sequence in the transition section and the stable section respectively, so as to determine the target current value;

[0147] The capacitance value determination module 305 is used to determine the capacitance value of the capacitor of the power module under test at the current moment based on the target voltage change value and the target current value.

[0148] In the above embodiment, the arm current sequence and capacitor voltage sequence of the power module under test are acquired over a period of time, and the target switching stage is determined within this period. Then, the reference voltage of the capacitor voltage sequence in the stable and calibration stages is calculated separately. References are established in both the stable and calibration stages to determine the reference drift. Based on this, the original voltage change value is dynamically corrected to obtain a more accurate target voltage change value. Simultaneously, a piecewise weighted integral is introduced in the processing of the arm current sequence. The current weighted integral is calculated according to the different dynamic characteristics of the transition and stable stages. Energy loss at different stages is compensated by coefficient weighting, making the current integral more accurately reflect the actual energy storage change of the capacitor, further ensuring the accuracy of the target current value. Finally, the capacitance value is calculated using these two optimized key physical quantities, making the result closer to the actual state of the capacitor. In this process, through structured signal segmentation and dynamic correction strategies, without overly relying on complex filtering algorithms, the influence of noise and measurement errors is effectively suppressed, and the computational complexity is significantly reduced. This ensures high estimation accuracy while enhancing the real-time response capability of the capacitance estimation method.

[0149] In one embodiment, the data acquisition module includes:

[0150] The data acquisition submodule is used to acquire the bridge arm current data and capacitor voltage sequence of the power module under test over a period of time.

[0151] The interpolation processing submodule is used to perform forward Newton interpolation on the bridge arm current data so that the processed bridge arm current data matches the sampling frequency of the capacitor voltage sequence.

[0152] The sequence generation submodule is used to generate a bridge arm current sequence based on the processed bridge arm current data.

[0153] In one embodiment, the voltage calculation module includes:

[0154] The first extraction submodule is used to extract the first voltage sequence of the capacitor voltage sequence in the stable section and calculate the average value of the first voltage sequence to obtain the reference voltage of the stable section.

[0155] The second extraction submodule is used to extract the second voltage sequence of the capacitor voltage sequence in the calibration segment and calculate the average value of the second voltage sequence to obtain the reference voltage of the calibration segment.

[0156] In one embodiment, the voltage correction module includes:

[0157] The point determination submodule is used to determine the end point of the stable segment of the target delivery phase and the end point of the stable segment.

[0158] The voltage difference submodule is used to calculate the difference between the voltage value corresponding to the end point of the input stable segment and the voltage value corresponding to the end point of the stable segment in the capacitor voltage sequence, so as to obtain the original voltage change value.

[0159] In one embodiment, the voltage correction module includes:

[0160] The absolute value calculation submodule is used to calculate the absolute value of the difference between the calibration section reference voltage and the stable section reference voltage;

[0161] The first correction submodule is used to determine the voltage correction value by the difference between the calibration section reference voltage and the stable section reference voltage if the absolute value is not greater than a preset threshold; otherwise, it obtains the historical average reference of the stable section and the historical average reference of the calibration section, and determines the voltage correction value by the difference between the historical average reference of the calibration section and the stable section.

[0162] The secondary correction submodule is used to correct the original voltage change value based on the voltage correction value when the voltage correction value is determined, to obtain the corrected voltage change value, and to determine the proportion of the voltage change entering the stable segment to the sum of the transition segment and the stable segment. Based on this proportion, the corrected voltage change value is corrected a second time to obtain the target voltage change value.

[0163] In one embodiment, the current calculation module includes:

[0164] The coefficient acquisition submodule is used to acquire the current compensation coefficient of the transition section and the current compensation coefficient of the stable section, and to extract the first current sequence of the bridge arm current sequence in the transition section and the second current sequence in the stable section.

[0165] The weighted summation submodule is used to integrate the first current sequence and the second current sequence to obtain the first current integral and the second current integral. Then, using the current compensation coefficient of the transition section and the current compensation coefficient of the stabilization section, the first current integral and the second current integral are weighted and summed to obtain the target current value.

[0166] In one embodiment, the capacitance determination module includes:

[0167] The capacitance calculation submodule is used to calculate the quotient of the target current value and the target voltage change value, and to determine the calculation result as the preliminary capacitor capacitance value.

[0168] The capacitance filtering submodule is used to obtain the capacitance values ​​of the capacitors from the previous N time steps, and to perform a moving average filtering process on the initial capacitance value based on the capacitance values ​​from the previous N time steps to obtain the capacitance value of the capacitor of the power module under test at the current time step.

[0169] The division of modules in the above-described power module capacitor capacitance estimation device is merely illustrative. In other embodiments, the power module capacitor capacitance estimation device can be divided into different modules as needed to complete all or part of its functions. Each module in the above-described power module capacitor capacitance estimation device can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in or independent of the processor in a computer device in hardware form, or stored in the memory of a computer device in software form, so that the processor can call and execute the operations corresponding to each module.

[0170] In one embodiment, this application also provides a storage medium storing computer-readable instructions that, when executed by one or more processors, cause the one or more processors to perform the steps of the power module capacitor capacitance estimation method as described in any of the above embodiments.

[0171] In one embodiment, this application also provides a computer device storing computer-readable instructions that, when executed by one or more processors, cause the one or more processors to perform the steps of the power module capacitor value estimation method as described in any of the above embodiments.

[0172] Indicatively, such as Figure 4 As shown, Figure 4 This is a schematic diagram of the internal structure of a computer device 400 provided in an embodiment of this application. The computer device 400 can be provided as a server. (Refer to...) Figure 4 The computer device 400 includes a processing component 402, which further includes one or more processors, and memory resources represented by memory 401 for storing instructions, such as application programs, that can be executed by the processing component 402. The application programs stored in memory 401 may include one or more modules, each corresponding to a set of instructions. Furthermore, the processing component 402 is configured to execute instructions to perform the power module capacitor value estimation method of any of the above embodiments.

[0173] The computer device 400 may also include a power supply component 403 configured to perform power management of the computer device 400, a wired or wireless network interface 404 configured to connect the computer device 400 to a network, and an input / output (I / O) interface 405. The computer device 400 may operate on an operating system stored in memory 401, such as Windows Server™, Mac OS X™, Unix™, Linux™, Free BSD™, or similar.

[0174] Those skilled in the art will understand that Figure 4 The structure shown is merely a block diagram of a portion of the structure related to the present application and does not constitute a limitation on the computer device to which the present application is applied. Specific computer devices may include more or fewer components than those shown in the figure, or combine certain components, or have different component arrangements.

[0175] Finally, it should be noted that in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising a…" does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element. In this document, the singular forms "a," "an," and "the" may also include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprising / including” or “having” specify the presence of the stated features, wholes, steps, operations, components, parts or combinations thereof, but do not exclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts or combinations thereof. Meanwhile, the term “and / or” as used in this specification includes any and all combinations of the associated listed items.

[0176] The various embodiments in this specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. The various embodiments can be combined as needed, and the same or similar parts can be referred to each other.

[0177] The above description of the disclosed embodiments enables those skilled in the art to make or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for estimating the capacitance value of a power module capacitor, characterized in that, The method includes: The arm current sequence and capacitor voltage sequence of the power module under test are acquired over a period of time, and the target switching stage is determined within this period of time; the target switching stage includes a stable section, a transition section, a stable input section, and a calibration section. Calculate the reference voltages of the capacitor voltage sequence in the stable segment and the calibration segment respectively to obtain the reference voltage of the stable segment and the reference voltage of the calibration segment; The original voltage change value of the power module under test before and after the target switching stage is determined, and the original voltage change value is corrected based on the stable section reference voltage and the calibration section reference voltage to obtain the target voltage change value; The target current value is determined by calculating the current-weighted integral of the bridge arm current sequence in the transition section and the stabilization section, respectively. Based on the target voltage change value and the target current value, determine the capacitor value of the power module under test at the current moment.

2. The method for estimating the capacitance value of a power module capacitor according to claim 1, characterized in that, The acquisition of the bridge arm current sequence and capacitor voltage sequence of the power module under test over a period of time includes: Collect bridge arm current data and capacitor voltage sequence of the power module under test over a period of time; The bridge arm current data is subjected to forward Newton interpolation to make the processed bridge arm current data match the sampling frequency of the capacitor voltage sequence. Based on the processed arm current data, an arm current sequence is generated.

3. The method for estimating the capacitance value of a power module capacitor according to claim 1, characterized in that, The step of calculating the reference voltages of the capacitor voltage sequence in the stable segment and the calibration segment, respectively, to obtain the reference voltage of the stable segment and the reference voltage of the calibration segment, includes: Extract the first voltage sequence of the capacitor voltage sequence in the stable segment, and calculate the average value of the first voltage sequence to obtain the reference voltage of the stable segment; Extract the second voltage sequence of the capacitor voltage sequence in the calibration segment, and calculate the average value of the second voltage sequence to obtain the reference voltage of the calibration segment.

4. The method for estimating the capacitance value of a power module capacitor according to claim 1, characterized in that, Determining the original voltage change value of the power module under test before and after the target switching phase includes: Determine the end point of the stable segment of the target deployment phase and the end point of the stable segment; The original voltage change value is obtained by subtracting the voltage value corresponding to the end point of the stable segment from the voltage value corresponding to the end point of the stable segment in the capacitor voltage sequence.

5. The method for estimating the capacitance value of a power module capacitor according to claim 1, characterized in that, The step of correcting the original voltage change value based on the stable segment reference voltage and the calibration segment reference voltage to obtain the target voltage change value includes: Calculate the absolute value of the difference between the calibration section reference voltage and the stable section reference voltage; If the absolute value is not greater than a preset threshold, the difference between the calibration segment reference voltage and the stable segment reference voltage is determined as the voltage correction value; otherwise, the historical average reference of the stable segment and the historical average reference of the calibration segment are obtained, and the difference between the historical average reference of the calibration segment and the historical average reference of the stable segment is determined as the voltage correction value. Once the voltage correction value is determined, the original voltage change value is corrected based on the voltage correction value to obtain the corrected voltage change value. The proportion of the voltage change in the stable segment to the sum of the transition segment and the stable segment is determined. Based on this proportion, the corrected voltage change value is corrected a second time to obtain the target voltage change value.

6. The method for estimating the capacitance value of a power module capacitor according to claim 1, characterized in that, The step of calculating the current-weighted integral of the bridge arm current sequence in the transition section and the stabilization section respectively to determine the target current value includes: Obtain the current compensation coefficient of the transition section and the current compensation coefficient of the stabilization section, and extract the first current sequence of the bridge arm current sequence in the transition section and the second current sequence in the stabilization section. Integrating the first current sequence and the second current sequence yields a first current integral and a second current integral. Using the current compensation coefficient of the transition section and the current compensation coefficient of the stabilization section, the first current integral and the second current integral are weighted and summed to obtain the target current value.

7. The method for estimating the capacitance value of a power module capacitor according to any one of claims 1 to 6, characterized in that, Determining the capacitor value of the power module under test at the current moment based on the target voltage change value and the target current value includes: Calculate the quotient of the target current value and the target voltage change value, and determine the calculation result as the preliminary capacitor capacitance value; Obtain the capacitor values ​​of the previous N time steps at the current time step, and perform a moving average filtering process on the preliminary capacitor value based on the capacitor values ​​of the previous N time steps to obtain the capacitor value of the power module under test at the current time step.

8. A power module capacitor capacitance estimation device, characterized in that, The device includes: The data acquisition module is used to acquire the arm current sequence and capacitor voltage sequence of the power module under test over a period of time, and to determine the target switching stage within that period of time; the target switching stage includes a stabilization stage, a transition stage, a stabilization stage, and a calibration stage. The voltage calculation module is used to calculate the reference voltages of the capacitor voltage sequence in the stable segment and the calibration segment, respectively, to obtain the reference voltage of the stable segment and the reference voltage of the calibration segment; The voltage correction module is used to determine the original voltage change value of the power module under test before and after the target switching stage, and correct the original voltage change value based on the stable section reference voltage and the calibration section reference voltage to obtain the target voltage change value. The current calculation module is used to calculate the current-weighted integral of the bridge arm current sequence in the transition section and the stable input section, respectively, to determine the target current value; The capacitance value determination module is used to determine the capacitance value of the capacitor of the power module under test at the current moment based on the target voltage change value and the target current value.

9. A storage medium, characterized in that: The storage medium stores computer-readable instructions that, when executed by one or more processors, cause the one or more processors to perform the steps of the power module capacitor value estimation method as described in any one of claims 1 to 7.

10. A computer device, characterized in that, include: One or more processors, and memory; The memory stores computer-readable instructions that, when executed by the one or more processors, perform the steps of the power module capacitor value estimation method as described in any one of claims 1 to 7.

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