Method, device and equipment for predicting service life of direct-current bus capacitor and medium
By obtaining the ripple voltage of the DC bus capacitor and the three-phase load rate of the inverter circuit, the capacitor temperature rise and lifetime loss are estimated, solving the problems of high cost and complex calculation in the existing technology. This achieves low-cost and fast capacitor lifetime prediction, improving the safety and reliability of the system.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-08-30
- Publication Date
- 2026-03-10
AI Technical Summary
Existing technologies for estimating the lifespan of DC bus capacitors suffer from high costs, high sampling accuracy requirements, and complex calculations. Furthermore, methods based on artificial intelligence algorithms have slow training speeds, making it difficult to achieve fast and low-cost lifespan prediction.
By acquiring the ripple voltage of the DC bus capacitor and the three-phase load rate of the inverter circuit, the capacitor temperature rise is estimated, and the capacitor life loss is calculated based on the temperature rise and operating parameters. Online monitoring is carried out using the existing sampling device of the power supply system to avoid adding additional detection devices. Multivariate statistical analysis and regression fitting models are used for accurate prediction.
It enables low-cost and rapid capacitor lifetime prediction, improves computational efficiency and prediction accuracy, and ensures the safety and reliability of the system.
Smart Images
Figure CN121633643A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of power electronics technology, and in particular to a method, apparatus, equipment and dielectric for predicting the lifespan of a DC bus capacitor. Background Technology
[0002] In a data center's power supply system, the rectifier and inverter circuits are electrically connected via positive and negative DC buses. A DC bus capacitor is connected between these buses to store energy, balance instantaneous power, suppress bus voltage ripple, and improve DC power quality. Heat loss due to bus ripple current and the limited heat dissipation surface of the DC bus capacitor easily lead to increased internal temperature. Under the combined effect of ambient temperature and internal temperature rise, the electrolyte evaporates, causing the capacitor to age. Therefore, accurately predicting the lifespan of the DC bus capacitor can improve system safety and overall operational reliability.
[0003] In related technologies, some embodiments can sample the capacitance and internal resistance values of a capacitor by sampling voltage that is electrically connected to the DC bus capacitor, process the capacitance and resistance values based on an empirical degradation model, and estimate the capacitor's lifespan. However, setting up the sampling circuit requires disrupting the original circuit structure of the power supply system, and the sampling circuit requires high sampling accuracy, which in turn requires a large memory for storing the sampling data, resulting in high computational costs.
[0004] In other embodiments, artificial intelligence algorithms, such as neural networks and support vector machines, are used to process large amounts of historical capacitance degradation data. However, the convergence speed during training is slow, the required data is small, and the preparation time for computation is long.
[0005] How to estimate the lifespan of bus capacitors quickly and at low cost has become a key research focus. Summary of the Invention
[0006] This application provides a method, apparatus, device, and medium for predicting the lifespan of DC bus capacitors to solve the aforementioned technical problems.
[0007] In a first aspect, embodiments of this application provide a method for predicting the lifetime of a DC bus capacitor, wherein the DC bus capacitor is connected across DC buses, and the DC buses are electrically connected between a rectifier circuit and an inverter circuit; the method is applied to a controller, and the method includes:
[0008] Obtain the operating parameters of the DC bus capacitor, the three-phase load rate of the inverter circuit, and the remaining lifetime value; the operating parameters include the ripple voltage of the DC bus.
[0009] Based on the ripple voltage and the three-phase load rate, estimate the DC bus capacitor temperature rise;
[0010] The capacitor life loss is calculated based on the target operating parameters and the operating time of the DC bus capacitor using the target operating parameters; the target operating parameters include the temperature rise of the DC bus capacitor.
[0011] Based on the capacitor's lifetime loss, update and output the remaining lifetime value.
[0012] In the above technical solution, since ripple increases the heat loss of the capacitor, the load condition of the inverter circuit connected in parallel also increases the heat loss of the capacitor. The electronic equipment obtains the ripple voltage of the DC bus and the three-phase load rate of the inverter circuit, which are strongly correlated with the temperature rise of the DC bus capacitor, to estimate the temperature rise of the DC bus capacitor. This solves the problem of difficult online measurement of the internal temperature rise of the capacitor. Then, the target operating parameters, including the temperature rise of the DC bus capacitor, that affect the capacitor life are determined. Based on the DC bus capacitor operating at these target operating parameters and the corresponding operating time, the capacitor life loss is calculated, thereby determining the remaining life of the capacitor for monitoring the capacitor status. The sampling information in the above process can use the original sampling device of the power supply system, without the need to add additional detection devices for parameters such as capacitance and internal resistance, ensuring the low cost of implementing this method. The parameters that are strongly correlated with the heat loss of the capacitor are analyzed in detail and the corresponding temperature rise is estimated, thereby realizing the calculation of the capacitor life loss. The calculation is more targeted and improves the calculation efficiency.
[0013] This paper analyzes the impact of different stress factors on the temperature rise at the center of the capacitor, constructs a functional model of average load rate, ripple voltage, and temperature rise at the center of the capacitor, and conducts error analysis on seven functional models through regression fitting in multivariate statistical analysis. The optimal functional fitting model and piecewise prediction method are selected to predict the temperature rise at the center of the capacitor in real time, thereby achieving online life prediction of the bus capacitor. Based on the fusion technology of failure physics model and data-driven approach, health management of DC bus capacitors in the equipment is realized, improving the safety and reliability of system operation.
[0014] In one possible implementation, estimating the DC bus capacitor temperature rise based on the ripple voltage and the three-phase load rate includes:
[0015] Calculate the load balancing rate based on the three-phase load rate;
[0016] The temperature rise of the DC bus capacitor is estimated based on the ripple voltage, the average load rate, and the temperature rise estimation model.
[0017] In one possible implementation, estimating the DC bus capacitor temperature rise based on the ripple voltage, the average load rate, and the temperature rise estimation model includes:
[0018] Calculate the average load rate based on the three-phase load rate;
[0019] When the load balancing rate is greater than a preset balancing rate threshold, the DC bus capacitor temperature rise is estimated based on the ripple voltage, the average load rate, and the first temperature rise estimation model.
[0020] When the load balancing rate is less than or equal to the preset balancing rate threshold, the DC bus capacitor temperature rise is estimated based on the ripple voltage, the average load rate, and the second temperature rise estimation model.
[0021] The first temperature rise estimation model is a model fitted based on the first historical average load rate sampled at multiple historical moments and the corresponding historical ripple voltage and historical temperature rise, wherein the first historical average load rate is greater than the preset equalization threshold.
[0022] The second temperature rise estimation model is a model fitted based on the second historical average load rate sampled at multiple historical moments and the corresponding historical ripple voltage and historical temperature rise. The second historical average load rate is less than or equal to the preset equalization threshold.
[0023] In the above technical solution, the load balancing rate is determined based on the load conditions of the three-phase output of the inverter circuit. The first temperature rise estimation model and the second temperature rise estimation model are set in segments based on different load balancing rates to ensure the accuracy of the DC bus capacitor temperature rise estimation, thereby ensuring the accuracy of the subsequent capacitor life loss calculation.
[0024] In one possible implementation, before estimating the DC bus capacitor temperature rise based on the ripple voltage, the average load rate, and the temperature rise estimation model, the method further includes:
[0025] Multiple fitting models are obtained; the multiple fitting models include multiple benchmark fitting models and multiple mixed fitting models, wherein the mixed fitting model is a model constructed based on any at least two benchmark fitting models;
[0026] Based on the historical average load rate and the corresponding historical ripple voltage and historical temperature rise, the fitting error of each fitting model is calculated.
[0027] The fitting model corresponding to the smallest fitting error is determined as the temperature rise estimation model.
[0028] In the above technical solution, when selecting a temperature rise estimation model, the electronic device analyzes the historical average load rate and corresponding historical ripple voltage and historical temperature rise based on multiple benchmark fitting models and multiple hybrid models, fits different curves, and determines the fitting model with the smallest error as the temperature rise estimation model by analyzing the fitting error between the estimated data of each curve and the actual data, so as to ensure the accuracy of temperature rise estimation.
[0029] In one possible implementation, the capacitor lifetime loss is calculated based on the target operating parameters and the operating time of the DC bus capacitor under the target operating parameters, including:
[0030] Calculate the accelerated aging factor of the DC bus capacitor using the target operating parameters;
[0031] The product of the accelerated aging factor and the operating time of the DC bus capacitor is taken as the capacitor life loss.
[0032] In one possible implementation, calculating the accelerated aging factor of the DC bus capacitor applied to the target operating parameters includes:
[0033] Based on the temperature rise of the DC bus capacitor, the preset allowable temperature rise of the DC bus capacitor at the highest operating temperature, and the temperature rise rate constant, the ripple current accelerated aging factor is calculated; wherein, the temperature rise rate constant is related to the ripple current applied to the DC bus capacitor.
[0034] The accelerated aging factor is calculated based on the ripple current accelerated aging factor.
[0035] In one possible implementation, the target operating parameters include the actual operating voltage applied to the DC bus capacitor;
[0036] The accelerated aging factor is calculated based on the ripple current accelerated aging factor, including:
[0037] Based on the actual operating voltage, the rated operating voltage of the DC bus, and the voltage stress index, the bus voltage derating factor is calculated; the voltage stress index is an index set based on the sensitivity of the DC bus capacitor's lifespan to voltage stress.
[0038] The accelerated aging factor is calculated based on the product of the ripple current accelerated aging factor and the bus voltage derating factor.
[0039] In one possible implementation, the target operating parameter includes ambient temperature;
[0040] The accelerated aging factor is calculated based on the ripple current accelerated aging factor, including:
[0041] Based on the ambient temperature and the maximum operating temperature of the DC bus capacitor, calculate the ambient temperature accelerated aging factor.
[0042] The accelerated aging factor is calculated based on the product of the ambient temperature accelerated aging factor and the ripple current accelerated aging factor.
[0043] In the above technical solution, an accelerated aging factor is calculated based on at least one target operating parameter that affects the capacitor life. The time for executing the target operating parameter is converted into the capacitor life loss through the accelerated aging factor to ensure the accuracy of the capacitor life estimation.
[0044] In one possible implementation, updating the remaining lifetime value based on the capacitor's lifetime loss includes:
[0045] The difference between the remaining lifetime value and the capacitor lifetime loss is used as the updated remaining lifetime value.
[0046] Secondly, embodiments of this application provide a device for predicting the lifespan of a DC bus capacitor, comprising:
[0047] The acquisition module is used to obtain the operating parameters of the DC bus capacitor, the three-phase load rate of the inverter circuit, and the remaining lifetime value; the operating parameters include the ripple voltage of the DC bus.
[0048] The processing module is used to estimate the DC bus capacitor temperature rise based on the ripple voltage and the three-phase load rate.
[0049] The processing module is further configured to calculate the capacitor life loss based on the target operating parameters and the operating time of the DC bus capacitor using the target operating parameters; the target operating parameters include the temperature rise of the DC bus capacitor;
[0050] The processing module is also used to update and output the remaining lifespan value based on the capacitor's lifespan loss.
[0051] Thirdly, embodiments of this application provide an electronic device, including: a memory and a processor;
[0052] The memory stores computer-executed instructions;
[0053] The processor executes computer execution instructions stored in the memory, causing the processor to perform the method described in any one of the first aspects.
[0054] Fourthly, embodiments of this application provide a power supply system, including a rectifier circuit, an inverter circuit, a DC bus electrically connected between the rectifier circuit and the inverter circuit, a DC bus capacitor connected across the DC bus, and the electronic equipment as described in the third aspect.
[0055] Fifthly, embodiments of this application provide a computer-readable storage medium storing computer-executable instructions, which, when executed by a processor, are used to implement the first aspect and / or various possible implementations of the first aspect.
[0056] In a sixth aspect, embodiments of this application provide a computer program product, including a computer program that, when executed by a processor, implements the first aspect and / or various possible implementations of the first aspect.
[0057] This application provides a method, apparatus, device, and medium for predicting the lifespan of a DC bus capacitor. The method includes: obtaining the ripple voltage of the DC bus and the three-phase load rate of the inverter circuit, which are strongly correlated with the temperature rise of the DC bus capacitor, to estimate the temperature rise of the DC bus capacitor. This solves the problem of difficult online measurement of the internal temperature rise of the capacitor. Then, target operating parameters affecting the capacitor's lifespan, including the temperature rise of the DC bus capacitor, are determined. Based on the DC bus capacitor operating at these target operating parameters and the corresponding operating time, the capacitor's lifespan loss is calculated, thereby determining the remaining lifespan of the capacitor for monitoring its condition. The sampling information in the above process can use the existing sampling device of the power supply system, without the need for additional detection devices, ensuring low cost in implementing this method. The method focuses on analyzing parameters strongly correlated with capacitor heat loss to achieve capacitor lifespan loss calculation, making the calculation more targeted and improving computational efficiency. Attached Figure Description
[0058] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.
[0059] Figure 1 A schematic diagram illustrating a scenario for a method to predict the lifetime of a DC bus capacitor provided in this application;
[0060] Figure 2 A flowchart illustrating a method for predicting the lifetime of a DC bus capacitor provided in this application;
[0061] Figure 3 A flowchart illustrating a method for estimating the temperature rise of a DC bus capacitor provided in this application;
[0062] Figure 4 A fitted surface plot of a temperature rise estimation model provided in this application;
[0063] Figure 5 A flowchart illustrating a method for calculating capacitor life loss provided in this application;
[0064] Figure 6 A flowchart illustrating another method for predicting the lifetime of DC bus capacitors provided in this application;
[0065] Figure 7 A schematic diagram of the structure of the DC bus capacitor lifetime prediction device provided in this application;
[0066] Figure 8A schematic diagram of the structure of the electronic device provided in this application.
[0067] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation
[0068] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.
[0069] Figure 1 A schematic diagram illustrating a scenario for a DC bus capacitor lifetime prediction method provided in this application, as shown below. Figure 1 As shown, the specific application scenarios of this application include a traditional power supply system 00, a load 13, a sensor 14, and electronic equipment 15. Among them, the traditional power supply system 00 includes a rectifier circuit 10, a DC bus 11, and an inverter circuit 12.
[0070] The rectifier circuit 10 and the inverter circuit 12 are electrically connected to the positive and negative DC bus 11. A DC bus capacitor C is connected across the positive and negative DC bus 11 to store energy, balance instantaneous power, suppress bus voltage ripple, and improve DC power quality. Heat loss due to bus ripple current and the limited heat dissipation surface of the DC bus capacitor easily cause the internal temperature of the capacitor to rise. Under the combined effect of ambient temperature and internal temperature rise, the electrolyte evaporates, and the capacitor ages. Therefore, accurately predicting the lifespan of the DC bus capacitor can improve system safety and overall operational reliability.
[0071] Generally, sensor 14 is set up to detect relevant operating parameters and environmental parameters of DC bus capacitor, and electronic device 15, which is electrically connected to sensor 14, estimates the life of DC bus capacitor based on the sampled relevant operating parameters and environmental parameters.
[0072] In related technologies, some embodiments can sample the capacitance and internal resistance values of a capacitor by sampling voltage that is electrically connected to the DC bus capacitor, process the capacitance and resistance values based on an empirical degradation model, and estimate the capacitor's lifespan. However, setting up the sampling circuit requires disrupting the original circuit structure of the power supply system, and the sampling circuit requires high sampling accuracy, which in turn requires a large memory for storing the sampling data, resulting in high computational costs.
[0073] In other embodiments, artificial intelligence algorithms, such as neural networks and support vector machines, are used to process large amounts of historical capacitance degradation data. However, the convergence speed during training is slow, the required data is small, and the preparation time for computation is long.
[0074] How to estimate the lifespan of bus capacitors quickly and at low cost has become a key research focus.
[0075] To address the aforementioned technical problems, this application provides a method, apparatus, device, and medium for predicting the lifespan of a DC bus capacitor. The technical concept of this application is as follows: An electronic device obtains the ripple voltage of the DC bus and the three-phase load rate of the inverter circuit, which are strongly correlated with the temperature rise of the DC bus capacitor, to estimate the temperature rise of the DC bus capacitor. This solves the problem of difficulty in online measurement of the internal temperature rise of the capacitor. Then, target operating parameters affecting the capacitor's lifespan, including the temperature rise of the DC bus capacitor, are determined. Based on the DC bus capacitor operating at these target operating parameters and the corresponding operating time, the capacitor's lifespan loss is calculated, thereby determining the remaining lifespan of the capacitor for monitoring its condition. The sampling information in the above process can utilize the existing sampling devices of the power supply system, eliminating the need for additional detection devices and ensuring low cost in implementing this method. Focusing on parameters strongly correlated with capacitor heat loss allows for targeted calculation of capacitor lifespan loss, improving computational efficiency.
[0076] The technical solution of this application and how the technical solution of this application solves the above-mentioned technical problems are described in detail below with specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments. The embodiments of this application will now be described with reference to the accompanying drawings.
[0077] Figure 2 A flowchart illustrating a method for predicting the lifetime of a DC bus capacitor provided in this application is shown below. Figure 2 As shown, the method includes:
[0078] S201. Obtain the operating parameters of the DC bus capacitor, the three-phase load rate of the inverter circuit, and the remaining life value.
[0079] Operating parameters include the ripple voltage of the DC bus.
[0080] In some embodiments, the operating parameters of the DC bus capacitor include the ripple current and ripple voltage applied to the DC bus capacitor.
[0081] In some embodiments, the ripple current is taken as its effective value;
[0082] In some embodiments, the ripple voltage is taken as its effective value;
[0083] In some embodiments, the electronic device also obtains relevant temperature information of the DC bus capacitor, including ambient temperature information.
[0084] In some embodiments, the ambient temperature of a DC bus capacitor can be determined by measuring its surface temperature.
[0085] The inverter circuit includes three-phase output terminals, and the electronic equipment obtains the load rate of each phase output terminal.
[0086] The load factor is the ratio of the actual load to the rated load.
[0087] S202. Estimate the DC bus capacitor temperature rise based on ripple voltage and three-phase load rate.
[0088] In some embodiments, the electronic device may obtain a temperature rise estimation model, which processes the ripple voltage and three-phase load rate to estimate the DC bus capacitor temperature rise. The temperature rise estimation model is a fitting function model used to characterize the load rate, ripple voltage, and capacitor temperature rise. The DC bus capacitor temperature rise represents the difference between the internal temperature of the DC bus capacitor and its surface temperature (i.e., ambient temperature).
[0089] This temperature rise can be estimated without the need for a temperature sensor inside the capacitor.
[0090] In some embodiments, the electronic device can estimate the temperature rise of the capacitor in real time online.
[0091] S203. Calculate the capacitor life loss based on the target operating parameters and the operating time of the DC bus capacitor application target operating parameters.
[0092] The target operating parameters include the temperature rise of the DC bus capacitor.
[0093] The electronic equipment determines the operating parameters that affect the lifespan of the DC bus capacitor as the target operating parameters, and converts the time the DC bus capacitor operates under these target operating parameters to the capacitor lifespan scale to determine the amount of capacitor lifespan loss that occurs when the DC bus capacitor operates under these target operating parameters.
[0094] S204. Based on the capacitor's lifespan loss, update and output the remaining lifespan value.
[0095] In some embodiments, the difference between the remaining lifetime value and the capacitor lifetime loss is used as the updated remaining lifetime value.
[0096] In the above technical solution, the electronic equipment obtains the ripple voltage of the DC bus and the three-phase load rate of the inverter circuit, which are strongly correlated with the temperature rise of the DC bus capacitor, to estimate the temperature rise of the DC bus capacitor. This solves the problem of difficulty in online measurement of the internal temperature rise of the capacitor. Then, the target operating parameters, including the temperature rise of the DC bus capacitor, that affect the capacitor life are determined. Based on the DC bus capacitor operating at these target operating parameters and the corresponding operating time, the capacitor life loss is calculated, thereby determining the remaining life of the capacitor for monitoring the capacitor status. The sampling information in the above process can use the existing sampling device of the power supply system, without the need to add additional detection devices, ensuring the low cost of implementing this method. The focus on analyzing parameters strongly correlated with capacitor heat loss to realize the calculation of capacitor life loss makes the calculation more targeted and improves the calculation efficiency.
[0097] Figure 3 A flowchart illustrating a method for estimating the temperature rise of a DC bus capacitor provided in this application is shown below. Figure 3 As shown, it includes:
[0098] S2021. Calculate the average load rate based on the three-phase load rate.
[0099] In some embodiments, the average three-phase load rate is used as the average load rate.
[0100] S2022. Based on the ripple voltage, average load rate and temperature rise estimation model, estimate the temperature rise of the DC bus capacitor.
[0101] More specifically, the steps for estimating the DC bus capacitor temperature rise in electronic equipment include:
[0102] Calculate the load balancing rate based on the three-phase load rate;
[0103] The load balancing rate is the maximum absolute value of the difference between the load rates of two adjacent phases. For example, the three-phase load rate includes the load rate of phase A, phase B, and phase C. The maximum value is calculated as max{|phase A load rate - phase B load rate|, |phase B load rate - phase C load rate|, |phase C load rate - phase A load rate|}.
[0104] When the load balancing rate is greater than the preset balancing rate threshold, the DC bus capacitor temperature rise is estimated based on the ripple voltage, average load rate and the first temperature rise estimation model.
[0105] When the load balancing rate is less than or equal to the preset balancing rate threshold, the DC bus capacitor temperature rise is estimated based on the ripple voltage, average load rate, and second temperature rise estimation model.
[0106] Among them, the first temperature rise estimation model is a model fitted based on the first historical average load rate sampled at multiple historical moments and the corresponding historical ripple voltage and historical temperature rise. The first historical average load rate is greater than the preset equalization threshold.
[0107] The second temperature rise estimation model is a model fitted based on the second historical average load rate sampled at multiple historical moments and the corresponding historical ripple voltage and historical temperature rise. The second historical average load rate is less than or equal to the preset equalization threshold.
[0108] The temperature rise estimation model was selected from multiple fitting models based on the fitting error.
[0109] The specific steps for obtaining the temperature rise estimation model include:
[0110] Multiple fitting models are obtained; the multiple fitting models include multiple benchmark fitting models and multiple mixed fitting models, and the mixed fitting model is a model constructed based on any two or more benchmark fitting models;
[0111] The benchmark fitting model includes:
[0112] The linear regression model equation includes: f(x,y)=ax+by+c;
[0113] The fitting equation for the exponential model includes: f(x,y)=a*exp(bx+cy);
[0114] The fitting equation for the power function model includes: f(x,y)=(ax+by) 2 ;
[0115] The fitting equations for the polynomial model include:
[0116] f(x,y)=ax 2 +by 2 +cxy+dx+ey+f;
[0117] The fitting equations for the Gaussian model include:
[0118]
[0119] Mixed fitting models include:
[0120] The combined equations of the hybrid model, exponential model, and polynomial model include:
[0121] f(x,y)=a*exp(bx+cy)+dx 2 +ey 2 +fxy+gx+hy+l;
[0122] The combined equations of the hybrid model, exponential model, and power function model include:
[0123] f(x,y)=a*exp(bx+cy)+(dx+ey) 2 ;
[0124] Where f(x,y) is a function representing the influence of ripple voltage x and average load rate y on the internal temperature rise of the capacitor. Based on the historical average load rate and the corresponding historical ripple voltage and historical temperature rise, the parameters of each fitting model are calculated. Then, the historical data are processed using the fitted parameters to estimate the historical temperature rise and compare it with the actual historical temperature rise to determine the fitting error.
[0125] The fitting model corresponding to the smallest fitting error is determined as the temperature rise estimation model.
[0126] In some embodiments, the fitting error includes the root mean square error. By comparing the root mean square errors, it can be seen that the exponential polynomial mixture model can better fit the changing trend of the known test data, so the exponential polynomial mixture model is preferred for predicting the capacitor temperature rise.
[0127] The fitted surface plot of the first temperature rise estimation model is shown below. Figure 4 As shown. Figure 4 It can be seen that when the load balancing rate is high, for the same average load rate, the temperature rise at the center of the capacitor increases with the increase of the ripple voltage. For the same ripple voltage, the temperature rise at the center of the capacitor increases with the increase of the average load rate. Moreover, the average load rate has a greater impact on the temperature rise of the capacitor than the ripple voltage.
[0128] In the above technical solution, when selecting a temperature rise estimation model, the electronic device analyzes the historical average load rate and corresponding historical ripple voltage and historical temperature rise based on multiple benchmark fitting models and multiple hybrid models, fits different curves, and determines the fitting model with the smallest error as the temperature rise estimation model by analyzing the fitting error between the estimated data of each curve and the actual data, so as to ensure the accuracy of temperature rise estimation.
[0129] Figure 5 A flowchart illustrating a method for calculating capacitor lifespan loss provided in this application is shown below. Figure 5 As shown, the method includes:
[0130] S2031. Calculate the accelerated aging factor of the DC bus capacitor for the target operating parameters.
[0131] The accelerated aging factor is a reduction factor for operating time in the physical model of capacitor aging failure, which is based on the Arrhenius equation and considers the effects of ambient temperature, ripple current, and bus voltage. Operating time refers to the time required to execute the target operating parameters.
[0132] In some embodiments, the physical model for capacitor aging failure is: Lx = L0 - K × T, where Lx is the remaining lifespan of the bus capacitor after executing the target operating parameters, Lx is the remaining lifespan of the bus capacitor before executing the target operating parameters, K is the accelerated aging factor, T is the running time of the bus capacitor executing the target operating parameters, and K × T is the amount of capacitor lifespan loss.
[0133] In some embodiments, the electronic device calculates the ripple current accelerated aging factor based on the DC bus capacitor temperature rise, the preset allowable temperature rise of the DC bus capacitor at the highest operating temperature, and the temperature rise rate constant, so that the electronic device can calculate the accelerated aging factor based on the ripple current accelerated aging factor.
[0134] The formulas for calculating the aging factor accelerated by ripple current include: Where 'a' represents the temperature rise rate constant, which is related to the ripple current applied to the DC bus capacitor and generally ranges from 2 to 4; ΔT0 represents the temperature rise of the DC bus capacitor, and ΔT represents the preset allowable temperature rise of the DC bus capacitor at its highest operating temperature.
[0135] The target operating parameters include the actual operating voltage applied to the DC bus capacitor. Based on the actual operating voltage, the rated operating voltage of the DC bus, and the voltage stress index, the bus voltage derating factor is calculated so that the electronic equipment can calculate the accelerated aging factor based on the product of the ripple current accelerated aging factor and the bus voltage derating factor. The voltage stress index is an index set based on the sensitivity of the DC bus capacitor's lifespan to voltage stress.
[0136] The formulas for calculating the bus voltage derating factor include: Where U represents the actual operating voltage, U O This indicates the rated operating voltage of the DC bus, and n represents the voltage stress index, which is generally between 3 and 5. The larger the n is, the more sensitive the capacitor life is to voltage stress.
[0137] When the target operating parameters include ambient temperature, the ambient temperature accelerated aging factor is calculated based on the ambient temperature and the maximum operating temperature of the DC bus capacitor, so that the electronic equipment can calculate the accelerated aging factor based on the product of the ambient temperature accelerated aging factor and the ripple current accelerated aging factor.
[0138] The formulas for calculating the environmental temperature-accelerated aging factor include: Wherein, T0 represents the maximum operating temperature of the DC bus capacitor, which is a preset data provided in the capacitor datasheet, and T represents the ambient temperature. In some embodiments, T can be the temperature of the capacitor casing.
[0139] S2032. The product of the accelerated aging factor and the operating time of the DC bus capacitor is used as the capacitor life loss. In the above technical solution, the accelerated aging factor corresponding to at least one target operating parameter affecting the capacitor life is calculated, and the time for executing the target operating parameter is converted into the capacitor life loss through the accelerated aging factor to ensure the accuracy of the capacitor life estimation.
[0140] Figure 6 A flowchart illustrating another method for predicting the lifetime of DC bus capacitors provided in this application is shown below. Figure 6 As shown, the method includes:
[0141] S301. Obtain the lifespan value of the DC bus capacitor, the operating parameters of the DC bus capacitor, and the three-phase load rate of the inverter circuit.
[0142] When the power supply system restarts after a power outage, the system reads the lifespan value of the DC bus capacitor, the operating parameters of the DC bus capacitor, and the three-phase load rate of the inverter circuit from the storage at historical moments.
[0143] When the power supply system is running, it determines whether the DC bus capacitor is a new capacitor. If it is a new capacitor, it reads the new bus capacitor's factory life value and other settings through SCI communication and stores them in the memory.
[0144] When it is not a new capacitor, read the capacitor's lifetime value from memory.
[0145] Then, based on the sensors, the operating parameters of the DC bus capacitor and the three-phase load rate of the inverter circuit are obtained, and the sampled information is stored in the value memory.
[0146] S302. Based on ripple voltage and three-phase load rate, estimate the DC bus capacitor temperature rise to calculate the ripple current accelerated aging factor.
[0147] S303. Calculate the bus voltage derating factor based on the actual operating voltage, the rated operating voltage of the DC bus, and the voltage stress index.
[0148] S304. Calculate the ambient temperature accelerated aging factor based on the ambient temperature and the maximum operating temperature of the DC bus capacitor.
[0149] S305. Calculate the accelerated aging factor of DC bus capacitor based on ripple current accelerated aging factor, bus voltage derating factor, and ambient temperature accelerated aging factor.
[0150] S306. The product of the accelerated aging factor of the DC bus capacitor and the operating time of the DC bus capacitor to achieve the accelerated aging factor is taken as the capacitor life loss.
[0151] S307. Update the current lifespan value and capacitor lifespan loss of the DC bus capacitor and display the lifespan value of the DC bus capacitor.
[0152] In some embodiments, the lifetime value is stored in memory via I2C and then sent to the monitoring side via SCI to display the health status of the capacitor.
[0153] S308. Determine whether the lifespan value of the DC bus capacitor is less than the first preset threshold.
[0154] If yes, proceed to step S310; otherwise, proceed to step S309.
[0155] S309. Determine whether the lifespan value of the DC bus capacitor is less than the second preset threshold.
[0156] If yes, proceed to step S311; otherwise, proceed to step S301.
[0157] The first preset threshold is less than the second preset threshold.
[0158] S310, Output capacitor lifespan depletion warning.
[0159] After this step is completed, proceed to step S301 to continue monitoring the capacitor's operating status and lifespan.
[0160] S311, Low lifespan warning for output capacitor.
[0161] After this step is completed, proceed to step S301 to continue monitoring the capacitor's operating status and lifespan.
[0162] Figure 7 A schematic diagram of the DC bus capacitor lifetime prediction device provided in this application is shown below. Figure 7 As shown, the DC bus capacitor lifetime prediction device 400 provided in this embodiment includes:
[0163] The acquisition module 401 is used to obtain the operating parameters of the DC bus capacitor, the three-phase load rate of the inverter circuit, and the remaining lifetime value; the operating parameters include the ripple voltage of the DC bus; wherein, the DC bus capacitor is connected across the DC bus, and the DC bus is electrically connected between the rectifier circuit and the inverter circuit;
[0164] Processing module 402 is used to estimate the DC bus capacitor temperature rise based on ripple voltage and three-phase load rate;
[0165] The processing module 402 is also used to calculate the capacitor life loss based on the target operating parameters and the operating time of the DC bus capacitor application of the target operating parameters; the target operating parameters include the DC bus capacitor temperature rise;
[0166] The processing module 402 is also used to update and output the remaining life value based on the capacitor's life loss.
[0167] In one possible implementation, the processing module 402 is specifically used for:
[0168] Calculate the average load rate based on the three-phase load rate;
[0169] Based on the ripple voltage, average load rate, and temperature rise estimation model, the temperature rise of the DC bus capacitor is estimated.
[0170] In one possible implementation, the processing module 402 is specifically used for:
[0171] Calculate the load balancing rate based on the three-phase load rate;
[0172] When the load balancing rate is greater than the preset balancing rate threshold, the DC bus capacitor temperature rise is estimated based on the ripple voltage, average load rate and the first temperature rise estimation model.
[0173] When the load balancing rate is less than or equal to the preset balancing rate threshold, the DC bus capacitor temperature rise is estimated based on the ripple voltage, average load rate, and second temperature rise estimation model.
[0174] Among them, the first temperature rise estimation model is a model fitted based on the first historical average load rate sampled at multiple historical moments and the corresponding historical ripple voltage and historical temperature rise. The first historical average load rate is greater than the preset equalization threshold.
[0175] The second temperature rise estimation model is a model fitted based on the second historical average load rate sampled at multiple historical moments and the corresponding historical ripple voltage and historical temperature rise. The second historical average load rate is less than or equal to the preset equalization threshold.
[0176] In one possible implementation, the processing module 402 is specifically used for:
[0177] Multiple fitting models are obtained; the multiple fitting models include multiple benchmark fitting models and multiple mixed fitting models, and the mixed fitting model is a model constructed based on any two or more benchmark fitting models;
[0178] Based on the historical average load rate and the corresponding historical ripple voltage and historical temperature rise, the fitting error of each fitting model is calculated.
[0179] The fitting model corresponding to the smallest fitting error is determined as the temperature rise estimation model.
[0180] In one possible implementation, the processing module 402 is specifically used for:
[0181] Calculate the accelerated aging factor for the target operating parameters of the DC bus capacitor;
[0182] The product of the accelerated aging factor and the operating time of the DC bus capacitor is taken as the capacitor life loss.
[0183] In one possible implementation, the processing module 402 is specifically used for:
[0184] Based on the temperature rise of the DC bus capacitor, the preset allowable temperature rise of the DC bus capacitor at the highest operating temperature, and the temperature rise rate constant, the ripple current accelerated aging factor is calculated; where the temperature rise rate constant is related to the ripple current applied to the DC bus capacitor.
[0185] Accelerated aging factor is calculated based on ripple current accelerated aging factor.
[0186] In one possible implementation, the processing module 402 is specifically used for:
[0187] The bus voltage derating factor is calculated based on the actual operating voltage, the rated operating voltage of the DC bus, and the voltage stress index; the voltage stress index is an index set based on the sensitivity of the DC bus capacitor's lifespan to voltage stress.
[0188] The accelerated aging factor is calculated based on the product of the ripple current accelerated aging factor and the bus voltage derating factor.
[0189] The target operating parameters include the actual operating voltage applied to the DC bus capacitor.
[0190] In one possible implementation, the processing module 402 is specifically used for:
[0191] Based on the ambient temperature and the maximum operating temperature of the DC bus capacitor, the ambient temperature accelerated aging factor is calculated.
[0192] The accelerated aging factor is calculated based on the product of the ambient temperature accelerated aging factor and the ripple current accelerated aging factor.
[0193] The target operating parameters include ambient temperature.
[0194] In one possible implementation, the processing module 402 is specifically used for:
[0195] The difference between the remaining lifetime value and the capacitor's lifetime loss is used as the updated remaining lifetime value.
[0196] The temperature control device provided in this embodiment can execute the method provided in the above method embodiment. Its implementation principle and technical effect are similar, and will not be described in detail here.
[0197] Figure 8 A schematic diagram of the control device provided in this application. Figure 7As shown, the electronic device 500 provided in this embodiment includes at least one processor 501 and a memory 502. Optionally, the device 500 further includes a communication component. The processor 501, memory 502, and communication component are connected via a bus.
[0198] In a specific implementation, at least one processor 501 executes computer execution instructions stored in memory 502, causing at least one processor 501 to perform the above-described method.
[0199] The specific implementation process of processor 501 can be found in the above method embodiments, and its implementation principle and technical effect are similar. It will not be repeated here.
[0200] In the above embodiments, it should be understood that the processor can be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), etc. The general-purpose processor can be a microprocessor or any conventional processor. The steps of the method disclosed in this invention can be directly implemented by a hardware processor, or implemented by a combination of hardware and software modules within the processor.
[0201] The memory may include random access memory (RAM) and may also include non-volatile memory (NVM), such as at least one disk storage device.
[0202] The bus can be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus, or an Extended Industry Standard Architecture (EISA) bus, etc. Buses can be categorized as address buses, data buses, control buses, etc. For ease of illustration, the buses shown in the accompanying drawings are not limited to a single bus or a single type of bus.
[0203] This application also provides a power supply system, including a rectifier circuit, an inverter circuit, a DC bus electrically connected between the rectifier circuit and the inverter circuit, a DC bus capacitor connected across the DC bus, and an electronic device, wherein the electronic device performs the DC bus capacitor lifetime prediction method in the above embodiments.
[0204] This application also provides a computer program product, including a computer program that, when executed by a processor, implements the above-described method.
[0205] This application also provides a computer-readable storage medium storing computer-executable instructions, which, when executed by a processor, implement the above-described method.
[0206] The aforementioned readable storage medium can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as static random access memory (SRAM), electrically erasable programmable read-only memory (EEPROM), erasable programmable read-only memory (EPROM), programmable read-only memory (PROM), read-only memory (ROM), magnetic storage, flash memory, magnetic disk, or optical disk. The readable storage medium can be any available medium accessible to a general-purpose or special-purpose computer.
[0207] An exemplary readable storage medium is coupled to a processor, enabling the processor to read information from and write information to the readable storage medium. Of course, the readable storage medium can also be a component of the processor. The processor and the readable storage medium can reside in an Application Specific Integrated Circuit (ASIC). Alternatively, the processor and the readable storage medium can exist as discrete components in the device.
[0208] The division of units is merely a logical functional division; in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be indirect coupling or communication connection through some interfaces, devices, or units, and may be electrical, mechanical, or other forms.
[0209] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.
[0210] In addition, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.
[0211] If a function is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this invention, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods of the various embodiments of this invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.
[0212] Those skilled in the art will understand that all or part of the steps of the above-described method embodiments can be implemented by hardware related to program instructions. The aforementioned program can be stored in a computer-readable storage medium. When executed, the program performs the steps of the above-described method embodiments; and the aforementioned storage medium includes various media capable of storing program code, such as ROM, RAM, magnetic disks, or optical disks.
[0213] Finally, it should be noted that other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This invention is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein, and is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of the invention is limited only by the appended claims.
Claims
1. A method for life prediction of a DC bus capacitor, characterized in that, A DC bus capacitor is connected in parallel between DC buses, the DC buses being electrically connected between a rectifier circuit and an inverter circuit; the method is applied to a controller, and the method comprises: obtaining an operating parameter of the DC bus capacitor, a three-phase load rate of the inverter circuit, and a remaining life value; the operating parameter comprises a ripple voltage of the DC bus; estimating a DC bus capacitor temperature rise based on the ripple voltage and the three-phase load rate; calculating a capacitor life loss amount based on a target operating parameter and a running time length of the DC bus capacitor applying the target operating parameter; the target operating parameter comprises the DC bus capacitor temperature rise; updating and outputting the remaining life value based on the capacitor life loss amount.
2. The method of claim 1, wherein, The method further comprises: calculating an average load rate based on the three-phase load rate; estimating the DC bus capacitor temperature rise based on the ripple voltage, the average load rate, and a temperature rise estimation model.
3. The method of claim 2, wherein, The method further comprises: calculating a load balance rate based on the three-phase load rate; when the load balance rate is greater than a preset balance rate threshold, estimating the DC bus capacitor temperature rise based on the ripple voltage, the average load rate, and a first temperature rise estimation model; when the load balance rate is less than or equal to the preset balance rate threshold, estimating the DC bus capacitor temperature rise based on the ripple voltage, the average load rate, and a second temperature rise estimation model; wherein the first temperature rise estimation model is a model fitted based on a plurality of first historical average load rates sampled at historical time points, corresponding historical ripple voltages, and historical temperature rises, the first historical average load rates being greater than the preset balance threshold; the second temperature rise estimation model is a model fitted based on a plurality of second historical average load rates sampled at historical time points, corresponding historical ripple voltages, and historical temperature rises, the second historical average load rates being less than or equal to the preset balance threshold.
4. The method according to claim 2 or 3, characterized in that, The method further comprises: obtaining a plurality of fitting models; the plurality of fitting models comprise a plurality of reference fitting models and a plurality of mixed fitting models, the mixed fitting models being models constructed based on any at least two reference fitting models; calculating a fitting error of each of the fitting models based on historical average load rates, corresponding historical ripple voltages, and historical temperature rises; determining a fitting model corresponding to a smallest fitting error as the temperature rise estimation model.
5. The method according to any one of claims 1-3, characterized in that, The method further comprises: calculating an acceleration aging factor of the DC bus capacitor applying the target operating parameter; taking a product of the acceleration aging factor and a running time length of the DC bus capacitor as the capacitor life loss amount.
6. The method of claim 5, wherein, The method further comprises: calculating an acceleration aging factor of the DC bus capacitor applying the target operating parameter; The ripple current acceleration aging factor is calculated based on the DC bus capacitor temperature rise, the preset allowed temperature rise of the DC bus capacitor at the highest working temperature, and a temperature rise rate constant, wherein the temperature rise rate constant is associated with the ripple current loaded on the DC bus capacitor. The acceleration aging factor is calculated based on the ripple current acceleration aging factor.
7. The method of claim 6, wherein, The target operating parameter includes an actual working voltage loaded on the DC bus capacitor. The acceleration aging factor is calculated based on the ripple current acceleration aging factor, including: A bus voltage derating coefficient is calculated based on the actual working voltage, a rated working voltage of the DC bus, and a voltage stress index. The voltage stress index is an index set based on the sensitivity of the life of the DC bus capacitor to the voltage stress. The acceleration aging factor is calculated based on the product of the ripple current acceleration aging factor and the bus voltage derating coefficient.
8. The method of claim 6, wherein, The target operating parameter includes an ambient temperature. The acceleration aging factor is calculated based on the ripple current acceleration aging factor, including: An ambient temperature acceleration aging factor is calculated based on the ambient temperature and the highest working temperature of the DC bus capacitor. The acceleration aging factor is calculated based on the product of the ambient temperature acceleration aging factor and the ripple current acceleration aging factor.
9. The method of claim 1, wherein, The remaining life value is updated based on the capacitor life loss amount, including: The difference between the remaining life value and the capacitor life loss amount is taken as the updated remaining life value.
10. A life prediction device of a direct current bus capacitor, characterized by, Including: An acquisition module is configured to obtain operating parameters of the DC bus capacitor, a three-phase load rate of an inverter circuit, and a remaining life value; the operating parameters include a ripple voltage of the DC bus; A processing module is configured to estimate a DC bus capacitor temperature rise based on the ripple voltage and the three-phase load rate. The processing module is further configured to calculate a capacitor life loss amount based on a target operating parameter and a time length during which the DC bus capacitor applies the target operating parameter; the target operating parameter includes the DC bus capacitor temperature rise. The processing module is further configured to update and output the remaining life value based on the capacitor life loss amount.
11. An electronic device, comprising: Including: A memory and a processor; The memory stores computer execution instructions; The processor executes the computer execution instructions stored in the memory, so that the processor executes the method of any one of claims 1-9.
12. A computer-readable storage medium, characterized in that, The computer readable storage medium stores computer execution instructions, and the computer execution instructions are executed by the processor to implement the method of any one of claims 1-9.