Reconfigurable converter power module switching control method and device, terminal and medium

Abstract

The invention discloses a reconfigurable converter power module switching control method and device, a terminal and a medium, and the method comprises the steps: building a power loss model and a power device electric heating model of a key power device of a converter through the collected environment temperature and electric parameters of the reconfigurable converter, and obtaining a power loss model and a power device electric heating model of the key power device of the converter according to the junction temperature parameter; through data fitting, constructing a relational expression between the junction temperature parameter and the thermal cycle failure times of the device; obtaining fatigue damage data of the power device according to the difference between the actual thermal cycle times and the thermal cycle failure times of the device; according to the comparison result of the accumulated values of the fatigue loss data of the power devices, the switching configuration information of the power modules of the converter is determined, and the setting of the module switching sequence according to the operation fatigue indexes of the power modules is realized, so that the service life balance degree of the modules is improved, the system operation fault occurrence rate is reduced, and the system stability of the converter is improved.

Description

Technical Field

[0001] The present application relates to the field of power distribution technology, and in particular to a method, device, terminal and medium for controlling switching of power modules of a reconfigurable converter. Background Art

[0002] The power electronic converter device used for DC distribution network is characterized by high withstand voltage and large device capacity. However, due to the limitation of the electrical stress level and capacity of the device, it is necessary to form its main topology through modular series-parallel connection of basic power circuits to access the DC distribution network. At present, modular power electronic system solutions have become the mainstream architecture of power electronic converters used for distribution network networking. An adaptive reconfigurable DC converter system consisting of multiple power modules and a switch matrix network is designed. The sub-power module adopts a bidirectional CLLC resonant circuit cascaded with a bidirectional Buck / Boost circuit.

[0003] The reconfigurable converter is applied to the electric vehicle DC fast charging station scene as an adaptive reconfigurable charging stack. The charging stack includes an electrically connected switch array and a DCDC power module, and the DCDC power module includes multiple power sub-modules. The method includes: obtaining the charging voltage and charging current of the electric vehicle; determining the number of corresponding power sub-modules in series according to the charging voltage of the electric vehicle, and determining the number of corresponding power sub-modules in parallel according to the charging current of the electric vehicle; determining the opening and closing of each switch device according to the number of power sub-modules in series and the number of power sub-modules in parallel, so as to determine the connection mode of each power sub-module in the DCDC power module, so as to charge the electric vehicle. The input and output ends of the DCDC power module are respectively connected to the flexible switch array to realize the dynamic reconfiguration of the series and parallel mode between modules. The on-off of the output switch array determines the series and parallel mode of each power module, and the on-off of the input switch array determines the opening and closing of each switch device.

[0004] However, when connecting different types of electric vehicles and different charging modes, the modules will operate in different states due to the different maximum charging powers of voltage and current required by different vehicles, resulting in different fatigue damage and different impacts on life. The existing switching control method cannot effectively balance the fatigue damage degree of each module, resulting in the technical problem of low stability of the converter system. Summary of the invention

[0005] The present application provides a reconfigurable converter power module switching control method, device, terminal and medium, which are used to solve the technical problem that the existing reconfigurable converter power module switching control method cannot effectively balance the fatigue damage degree of each module, resulting in low stability of the converter system.

[0006] In order to solve the above technical problems, the first aspect of the present application provides a switching control method for a power module of a reconfigurable converter, comprising:

[0007] Collect the ambient temperature and electrical parameters of the reconfigurable converter;

[0008] According to the electrical parameters, a power loss model of a key power device of the converter is constructed, wherein the power loss model is used to calculate the power loss parameters of the key power device of the converter;

[0009] According to the power loss parameter, in combination with the ambient temperature and the thermal resistance parameter of the power device, a power device electrothermal model is constructed, wherein the power device electrothermal model is used to calculate the junction temperature parameter of the key power device of the converter;

[0010] According to the junction temperature parameters, a relationship between the junction temperature parameters and the number of thermal cycle failures of the device is constructed through data fitting;

[0011] Obtaining fatigue damage data of the power device according to the difference between the actual number of thermal cycles and the number of thermal cycle failures of the device;

[0012] The switching configuration information of the power modules of the converter is determined according to the comparison result of the accumulated values ​​of fatigue loss data of each power device.

[0013] Preferably, the power loss model is specifically:

[0014]

[0015]

[0016]

[0017]

[0018] In the formula, is the power loss parameter of the power device, is the conduction loss of key power devices, is the effective value of the current flowing through the device, is the on-resistance, is the turn-off loss or turn-on loss of the power device, is the power loss of key power devices, is the current when the power device is turned off or on, , are the turn-on energy loss and turn-off energy loss of the power device, is the load current, , , , , , are the coefficients of the corresponding constant term, linear term and quadratic term obtained by curve fitting, , They are the turn-on energy ratio and the turn-off energy ratio respectively.

[0019] Preferably, the power device electrothermal model is specifically:

[0020]

[0021] In the formula, is the average junction temperature of the power device, is the power loss parameter of the power device, is the thermal resistance from the hot spot of the power device to the case, is the thermal resistance from the power device case to the thermal connection material, is the thermal resistance of the thermal connection material to the environment, is the ambient temperature.

[0022] Preferably, the method for obtaining the junction temperature parameter specifically includes:

[0023] Based on the power device electrothermal model, the thermal profile junction temperature data of the power device is obtained, and then based on the thermal profile junction temperature data, the average junction temperature and the junction temperature fluctuation are calculated by the rain flow counting method as the junction temperature parameter.

[0024] Preferably, the relationship between the junction temperature parameter and the number of thermal cycle failures of the device is specifically:

[0025]

[0026] In the formula, is the number of device thermal cycle failures, A and β are fitting coefficients, is the activation energy, is the Boltzmann constant, is the junction temperature fluctuation, is the average junction temperature.

[0027] Preferably, obtaining fatigue damage data of a power device according to the difference between the actual number of thermal cycles and the number of thermal cycle failures of the device specifically includes:

[0028] According to the ratio of the actual number of thermal cycles to the number of thermal cycle failures of the device, fatigue damage data of the power device in this thermal cycle period is obtained.

[0029] Preferably, determining the switching configuration information of the power modules of the converter according to the comparison result of the accumulated values ​​of fatigue loss data of each power device specifically includes:

[0030] When the power module completes a charging task, the fatigue damage data of the power device in previous thermal cycles is combined to update the accumulated value of fatigue loss data of the power device;

[0031] The switching configuration information of the power modules of the converter is determined according to the comparison result of the accumulated values ​​of fatigue loss data of each power device.

[0032] At the same time, the second aspect of the present application provides a reconfigurable converter power module switching control device, including:

[0033] A parameter acquisition unit, used for collecting the ambient temperature and electrical parameters of the reconfigurable converter;

[0034] A power loss model building unit, used to build a power loss model of a key power device of the converter according to the electrical parameters, wherein the power loss model is used to calculate the power loss parameters of the key power device of the converter;

[0035] A device electrothermal model building unit, used to build a power device electrothermal model according to the power loss parameter, in combination with the ambient temperature and the thermal resistance parameter of the power device, wherein the power device electrothermal model is used to calculate the junction temperature parameter of the key power device of the converter;

[0036] A cycle failure relationship building unit, used to build a relationship between the junction temperature parameter and the number of thermal cycle failures of the device through data fitting according to the junction temperature parameter;

[0037] A fatigue damage data calculation unit, used to obtain fatigue damage data of the power device according to the difference between the actual number of thermal cycles and the number of thermal cycle failures of the device;

[0038] The power module switching configuration determining unit is used to determine the power module switching configuration information of the converter according to the comparison result of the accumulated values ​​of fatigue loss data of each power device.

[0039] A third aspect of the present application provides a reconfigurable converter power module switching control terminal, including: a memory and a processor;

[0040] The memory is used to store program codes, and the program codes are used to implement a reconfigurable converter module switching control method as provided in the first aspect of the present application;

[0041] The processor is used for reading and executing the program code.

[0042] The fourth aspect of the present application provides a computer-readable storage medium, in which a program code is stored. The program code is used to be read and executed by a processor to implement a reconfigurable converter power module switching control method as provided in the first aspect of the present application.

[0043] It can be seen from the above technical solutions that this application has the following advantages:

[0044] The solution provided in the present application constructs a power loss model and an electro-thermal model of the key power devices of the converter by collecting the ambient temperature and electrical parameters of the reconfigurable converter, and constructs a relationship between the junction temperature parameters and the number of thermal cycle failures of the device through data fitting according to the junction temperature parameters; obtains fatigue damage data of the power device based on the difference between the actual number of thermal cycles and the number of thermal cycle failures of the device; determines the power module switching configuration information of the converter based on the comparison result of the cumulative value of the fatigue loss data of each power device, and realizes the setting of the module switching sequence according to the operating fatigue index of the power module, thereby improving the life balance of each module, reducing the occurrence rate of system operation failures, and improving the stability of the converter system. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0046] Figure 1 A schematic flow chart of an embodiment of a reconfigurable converter power module switching control method provided in the present application.

[0047] Figure 2 A schematic flow chart of the switching sequencing logic in an embodiment of a reconfigurable converter power module switching control method provided in the present application.

[0048] Figure 3 A schematic diagram of the structure of an adaptively reconfigurable charging system for implementing a reconfigurable converter power module switching control method provided in the present application.

[0049] Figure 4 This is a diagram showing the fatigue damage variation based on the traditional module number sequential switching scheme under scenario one.

[0050] Figure 5 This is a diagram showing the fatigue damage changes based on the traditional charging sequence cyclic switching under scenario one conditions.

[0051] Figure 6 This is a fatigue damage change diagram based on the switching scheme of this application under scenario one conditions.

[0052] Figure 7 This is a diagram showing the fatigue damage changes based on the traditional module number sequential switching scheme under scenario two.

[0053] Figure 8 This is a diagram showing the fatigue damage changes based on the traditional charging sequence cyclic switching under scenario two conditions.

[0054] Fig. 9 This is a fatigue damage change diagram based on the switching scheme of this application under scenario two conditions.

[0055] Fig.10 The figure is a comparison of the fatigue damage balance effects of the three switching schemes after 6000 hours of implementation under two scenario conditions.

[0056] Fig.11 The figure is a comparison chart of the cumulative fatigue damage values ​​of different switching schemes at 6000h.

[0057] Fig.12 A schematic structural diagram of an embodiment of a reconfigurable converter power module switching control device provided in the present application.

[0058] Fig.13 A structural schematic diagram of an embodiment of a reconfigurable converter power module switching control terminal provided in the present application. DETAILED DESCRIPTION

[0059] When connecting different types of electric vehicles and different charging modes, the modules will work in different states due to the different maximum charging powers of voltage and current required by different vehicles, resulting in different fatigue damage and different impacts on life. When selecting modules, the traditional solution switches according to the module number. By default, the corresponding module is selected from the free modules from the smallest to the largest module number for each charging. This will lead to inconsistent working time and fatigue levels of each module. As the working time progresses, the gap in fatigue damage between modules continues to increase, which leads to inconsistent module failure time. The earliest module failure time is used as the system damage time, which reduces the life balance and reduces the reconfigurable converter. The second conventional solution switches in sequence in a cycle. The modules are selected in sequence each time they are charged. When the charging cycle changes, the modules are selected in a cycle in sequence. This solution will not continuously expand the fatigue damage between modules like the traditional solution. It is more reliable than the traditional solution, but it cannot achieve balanced fatigue damage, and the effect on extending the system life and improving reliability is average.

[0060] In view of this, an embodiment of the present application provides a reconfigurable converter power module switching control method, device, terminal and medium, which are used to solve the technical problem that the existing reconfigurable converter power module switching control method cannot effectively balance the fatigue damage degree of each module, resulting in low stability of the converter system.

[0061] In order to make the purpose, features, and advantages of the invention of this application more obvious and easy to understand, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the embodiments described below are only part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0062] First, a detailed description of an embodiment of a reconfigurable converter power module switching control method provided by the present application is as follows:

[0063] See also Figure 1 , a reconfigurable converter power module switching control method provided in an embodiment of the present application includes:

[0064] Step 101: Collect the ambient temperature and electrical parameters of the reconfigurable converter.

[0065] It should be noted that when implementing the technical solution of the present application, the ambient temperature and electrical parameters are first collected through the environmental stress and operating state of the converter system, where the electrical parameters mainly include: charging voltage, charging current, etc.

[0066] Step 102: Construct a power loss model of key power devices of the converter according to electrical parameters.

[0067] Among them, the power loss model is used to calculate the power loss parameters of the key power devices of the converter.

[0068] It should be noted that, then, based on the electrical parameters obtained in step 101 and in combination with the converter model, a power loss model of key components is constructed. The calculation formula of the power loss model is as follows:

[0069]

[0070]

[0071]

[0072]

[0073] In the formula, is the power loss parameter of the power device, is the conduction loss of key power devices, is the effective value of the current flowing through the device, is the on-resistance, is the turn-off loss or turn-on loss of the power device, is the power loss of key power devices, is the current when the power device is turned off or on, , are the turn-on energy loss and turn-off energy loss of the power device, is the load current, , , , , , are the coefficients of the corresponding constant term, linear term and quadratic term obtained by curve fitting, , They are the turn-on energy ratio and the turn-off energy ratio respectively.

[0074] Among them, the turn-on energy ratio and the turn-off energy ratio can be obtained by testing the turn-on loss and turn-off loss of a certain load current, actual bus voltage and basic bus voltage in a double pulse test simulation, and dividing the loss obtained by the actual bus voltage by the loss obtained by the basic bus voltage.

[0075] Step 103: construct an electrothermal model of the power device according to the power loss parameter, combined with the ambient temperature and the thermal resistance parameter of the power device.

[0076] Among them, the power device electrothermal model is used to calculate the junction temperature parameters of the key power devices of the converter.

[0077] It should be noted that, based on the power loss parameters obtained in step 102 and the ambient temperature obtained in step 101, an electrothermal model of the power device is constructed. The thermal profile information of each component can be obtained using the electrothermal model. After obtaining the thermal profile, the junction temperature parameters of the key power devices of the converter are calculated based on the thermal profile.

[0078] The calculation formula of the power device electrothermal model mentioned in this embodiment is as follows:

[0079]

[0080] In the formula, is the average junction temperature of the power device, is the power loss parameter of the power device, is the thermal resistance from the hot spot of the power device to the case, is the thermal resistance from the power device case to the thermal connection material, is the thermal resistance of the thermal connection material to the environment, is the ambient temperature.

[0081] More specifically, the junction temperature parameters mentioned in this embodiment include: average junction temperature and junction temperature fluctuations , which can be extracted by the rainflow counting method.

[0082] Step 104: construct a relationship between the junction temperature parameters and the number of device thermal cycle failures through data fitting based on the junction temperature parameters.

[0083] It should be noted that based on the junction temperature parameters obtained in step 103, a relationship between the junction temperature parameters and the number of thermal cycle failures of the device is constructed through data fitting. Specifically, the relationship between the average junction temperature and the junction temperature fluctuation amplitude and the number of device cycle failures N can be considered according to the Coffin-Manson-Arrhenius model. f The influence of isotope is used to calculate the number of cycles to failure of power semiconductor devices.

[0084] More specifically, the relationship between the junction temperature parameter and the number of thermal cycle failures of the device is:

[0085]

[0086] In the formula, is the number of device thermal cycle failures, A and β are fitting coefficients, is the activation energy, is the Boltzmann constant, is the junction temperature fluctuation, is the average junction temperature.

[0087] Step 105: Obtain fatigue damage data of the power device according to the difference between the actual number of thermal cycles and the number of thermal cycle failures of the device.

[0088] It should be noted that the fatigue damage data of the power device is calculated based on the difference between the actual number of thermal cycles and the number of device thermal cycle failures, wherein the difference index between the actual number of thermal cycles and the number of device thermal cycle failures mentioned above is generally preferably characterized by a ratio, and in some embodiments, a difference may also be used for characterization. The specific calculation formula can be found in the following example:

[0089]

[0090] in, and is the number of cycles of the kth thermal cycle and the number of cycles that the device can withstand before failure under this thermal cycle. k is used to refer to the serial number of the thermal cycle mode of the power module.

[0091] Each time charging is completed, the life loss increment of the module is calculated and the total life loss of the module is updated.

[0092]

[0093] in, is the accumulated value of fatigue loss data, is the initial fatigue damage, $\Delta D_{ij}$ is the incremental cumulative fatigue damage during the charging cycle, where $i$ represents the serial number of the power module and $j$ represents the number of charging cycles.

[0094] Step 106: Determine the switching configuration information of the power modules of the converter according to the comparison results of the cumulative fatigue loss data values of each power device.

[0095] It should be noted that, taking the cumulative fatigue loss data value of each power device $i$ as the total life loss degree of the power module for sorting and selection, determine the switching configuration information of the power modules of the converter, and preferentially switch in the modules with less life loss.

[0096] Regarding the sorting of the power modules in this embodiment, the specific sorting logic can refer to the following example:

[0097] As Figure 2 shown, first obtain the current number of available modules $w$ of the charging stack, determine the number of modules $z$ to be put in according to the voltage and current information and capacity ratio of the charging vehicle. Each available module corresponds to its respective cumulative fatigue damage $D_1, D_2, D_3 \ldots D_w$. Use the swap flag variable $Swapped$ to track whether an element swap occurs in the current sorting round. Before starting the sorting, set the flag variable $Swapped$ to $True$ to ensure that the outer loop is executed at least once. The variable $i$ is the number of rounds of the outer loop. After each round of the outer loop is completed, the sorted area expands and the range of the inner loop shrinks. Initially set $i = 0$. The judgment condition of the outer loop is $swapped = true$ and $i < w - 1$, which means that an exchange occurred in the previous sorting round, indicating that the array may not be fully sorted yet and needs to continue sorting. $i < w - 1$ is used to control the number of rounds of the outer loop, and at most $n - 1$ rounds of sorting are performed. If the condition is yes, continue sorting; if it is no, the sorting ends and jumps to "End". Before the start of each round of the outer loop, set $swapped = False$, meaning it is assumed that no exchange will occur in the current round. If an exchange does occur in this round, $Swapped$ will be reset to $True$. The variable $j$ controls the traversal of the inner loop, which is used to compare and swap adjacent elements and is responsible for comparing and swapping adjacent modules one by one. Before the start of the inner loop, set $j = 0$. The judgment condition is $j < w - i - 1$. If the condition is yes, compare adjacent modules. If $D[j] > D[j + 1]$, then swap their positions and set $Swapped = True$, indicating that an exchange occurred in this round. If no exchange occurs in a certain round of the outer loop and $Swapped$ remains $False$, it means that the cumulative damage $D$ of all modules has been arranged in ascending order, and the sorting process can end提前结束,无需进行剩余的轮次。

[0098] This embodiment also provides an example of the technical effect description of the switching control solution of the present application, which is as follows:

[0099] Assuming an electric vehicle charging pile scenario, it involves an adaptively reconfigurable charging pile, which consists of a grid DC bus, a high-voltage switch array, n power modules, m low-voltage switch arrays and m charging guns. The system structure is shown in Figure 3 . Among them, each charging gun needs to be equipped with a low-voltage switch array, and each low-voltage switch array is connected in parallel. When designing the system, after determining the rated power of the module and the maximum power supported by the charging gun, the scope of each gun access module can be clarified, thereby simplifying the number of switches in the corresponding low-voltage switch array. The charging gun should be equipped with a basic number of modules to meet the charging needs of EVs of various voltage levels at any time. The maximum number of modules configured for the charging gun should be determined by the peak power designed for the charging gun.

[0100] According to the reconfigurable converter switching scheme provided in this embodiment, the mainstream electric vehicle types on the market are selected to design charging scenarios for switching strategies. The initial fatigue damage of the six power modules is set to be different, namely [0.16, 0.15, 0.14, 0.13, 0.12, 0.11]. A total of 6000h are analyzed. It takes 3h to complete a charge. Scenario 1 is that the vehicle type III is connected to the charging gun, and the maximum input module is 3. Therefore, 3 modules need to be selected from 6 free modules for charging; Scenario 2 is that the vehicle types I-VI are randomly connected to the charging gun, and the maximum input modules are 1, 2, 3, 4, 5, and 6, respectively. Therefore, different numbers of modules need to be selected from 6 free modules for charging. In the above two scenarios, the traditional switching scheme, the sequential switching scheme, and the life balance switching scheme are analyzed respectively, and the life balance effect and the cumulative fatigue damage value after 6000h charging are compared to compare the scheme effects.

[0101] Scenario 1: The analysis target is to charge an electric vehicle with 6 submodules. Taking electric vehicle III as an example, assuming that the single charging time is 3 hours, considering that 3 modules are required for each charging, and 1200 hours as the analysis scale, the initial fatigue damage of the six modules is set to [0.16, 0.15, 0.14, 0.13, 0.12, 0.11]. Considering the life loss of components in a single charge is 4.8838×10-5.

[0102] Traditional switching scheme: Based on the module number sequence, each charging is performed from small to large. Figure 4 As shown in the figure, in scenario 1, each time the module number is selected, modules 1, 2, and 3 are always put into use, resulting in a continuous increase in the accumulated fatigue damage of the modules and an increase in the degree of aging. At the 2000th charging cycle, the largest accumulated fatigue damage among the six modules is about 0.26.

[0103] Sequential switching scheme: The module number sequence is used as the standard. The modules are selected in sequence each time the battery is charged. When the charging cycle changes, the modules are selected in sequence. In scenario 1, the first selected modules are modules 1, 2, and 3. The second selected modules are modules 4, 5, and 6, and so on. Figure 5 As shown in the figure, the fatigue degree of the six modules all increased, but the fatigue damage balance effect could not be achieved. At the 2000th charging cycle, the maximum cumulative fatigue damage among the six modules was about 0.21.

[0104] The life balance switching solution provided by this application is: based on the module fatigue damage as the standard, each time charging, the modules are sorted and selected according to the fatigue damage, and the modules with the least fatigue damage are selected first. In scenario 1, each time charging, all modules are sorted according to the current fatigue damage, and the three modules with the least fatigue damage are selected for connection. Figure 6 As shown, fatigue balance is achieved around the 1000th charging cycle, and at the 2000th charging cycle, the largest accumulated fatigue damage among the six modules is about 0.183, with a good fatigue damage balance effect, which extends the service life of the converter and improves system reliability.

[0105] Scenario 2: With a total of 6 sub-modules for charging different electric vehicles as the analysis target, taking mainstream electric vehicle brands as an example, each charging requires 1, 2, 3, 4, 5, and 6 modules. The life loss of components for a single charge is [4.9245×10-5, 4.9076×10-5, 4.8838×10-5, 4.9169×10-5, 4.9366×10-5, 4.8937×10-5], respectively. Assuming that the time to complete a single charge is 3h, the initial fatigue damage of the six modules is set to [0.11, 0.12, 0.13, 0.14, 0.15, 0.16]. The analysis scale is 1200h. Charging is continuous during the analysis time, and different types of electric vehicles are charged randomly in sequence.

[0106] Traditional switching scheme: Based on the module number sequence, each time charging, the modules are selected from small to large. The fatigue damage changes are shown in the figure. In scenario 2, each time a different vehicle is randomly connected, the module number is selected according to the number of modules required, starting from module 1. When 1 module is needed, module 1 is connected. When 2 modules are needed, module 1 and module 2 are connected. When 3 modules are needed, module 1, module 2 and module 3 are connected, and so on. Fatigue damage is as follows: Figure 7 As shown in Figure 2, the difference in cumulative fatigue damage between modules continues to increase, and the degree of aging increases. At the 2000th charging cycle, the largest cumulative fatigue damage among the six modules is about 0.26.

[0107] Sequential switching scheme: The module number sequence is used as the standard. The modules are selected in sequence each time the battery is charged. When the charging cycle changes, the modules are selected in sequence. In scenario 2, each time a different vehicle is randomly connected, the module number is selected according to the required number of modules. When the first charging vehicle requires 3 modules, the selected modules are modules 1, 2, and 3. The second charging vehicle requires 1 module, so module 4 is selected. The third charging vehicle requires 4 modules, so modules 5, module 6, module 1, and module 2 are selected, and so on. Fatigue damage changes such as Figure 8 As shown in the figure, the fatigue degree of the six modules all increased, but the fatigue damage balance effect could not be achieved. At the 2000th charging cycle, the maximum cumulative fatigue damage among the six modules was about 0.22.

[0108] Life balance switching scheme: Based on module fatigue damage, each time charging, the modules are sorted and selected according to fatigue damage, and the modules with less fatigue damage are selected first. In scenario 2, different vehicles are randomly connected each time, and each time charging, the modules are selected according to the number of modules required and the order of fatigue damage, and the modules with less fatigue damage are selected first. Fatigue damage changes are as follows: Fig. 9 As shown, fatigue balance is achieved around the 1200th charging cycle, and at the 2000th charging cycle, the maximum accumulated fatigue damage among the six modules is about 0.19, with a good fatigue damage balance effect, which extends the service life of the converter and improves system reliability.

[0109] like Fig.10 As shown in the figure, parts (a) and (b) respectively show the fatigue damage balancing effects of the three schemes at 6000 hours in scenario 1 and scenario 2. It can be seen that in both scenarios, the traditional switching scheme has the worst balance and the largest fatigue difference, followed by the sequential switching scheme, and the life balanced switching scheme achieves balance.

[0110] like Fig.11 As shown, Fig.11 The cumulative fatigue damage values ​​of different schemes at 6000h show that in the two scenarios, the traditional switching scheme has the largest cumulative fatigue damage, the lowest reliability, and the shortest life. The sequential switching scheme is second. The life-balanced switching scheme has the smallest cumulative fatigue damage, the best life extension effect, and the highest reliability.

[0111] The above is a detailed description of an embodiment of a reconfigurable converter power module switching control method provided by the present application. The following is a detailed description of an embodiment of a reconfigurable converter power module switching control device provided by the present application.

[0112] See also Fig.12 , a reconfigurable converter power module switching control device provided in an embodiment of the present application includes:

[0113] The parameter acquisition unit 201 is used to collect the ambient temperature and electrical parameters of the reconfigurable converter;

[0114] A power loss model building unit 202 is used to build a power loss model of a key power device of the converter according to electrical parameters, and the power loss model is used to calculate power loss parameters of the key power device of the converter;

[0115] The device electrothermal model building unit 203 is used to build a power device electrothermal model according to the power loss parameter, combined with the ambient temperature and the thermal resistance parameter of the power device, and the power device electrothermal model is used to calculate the junction temperature parameters of the key power devices of the converter;

[0116] The cycle failure relationship building unit 204 is used to build a relationship between the junction temperature parameter and the number of thermal cycle failures of the device through data fitting according to the junction temperature parameter;

[0117] A fatigue damage data calculation unit 205 is used to obtain fatigue damage data of the power device according to the difference between the actual number of thermal cycles and the number of thermal cycle failures of the device;

[0118] The power module switching configuration determining unit 206 is used to determine the power module switching configuration information of the converter according to the comparison result of the accumulated values ​​of fatigue loss data of each power device.

[0119] In addition, the present application provides a detailed description of an embodiment of a reconfigurable converter power module switching control terminal and an embodiment of a computer-readable storage medium.

[0120] like Fig.13 As shown, a reconfigurable converter power module switching control terminal provided in an embodiment of the present application, the implementation types of the terminal include but are not limited to: personal computers, industrial computers, servers and embedded intelligent devices, the main components of the terminal include: a memory 33 and a processor 31, and the memory 33 and the processor 31 can be connected via a communication bus 34;

[0121] The memory 33 is used to store program codes, and the program codes are used to implement a switching control method of a reconfigurable converter power module as provided in the above embodiment;

[0122] The processor 31 is used to read and execute program codes.

[0123] A fourth aspect of the present application provides a computer-readable storage medium, in which a program code is stored. The program code is used to be read and executed by a processor to implement a reconfigurable converter power module switching control method as provided in the above embodiment.

[0124] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the terminals, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0125] In the several embodiments provided in the present application, it should be understood that the disclosed terminals, devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be an indirect coupling or communication connection through some interfaces, devices or units, which can be electrical, mechanical or other forms.

[0126] The terms "first", "second", "third", "fourth", etc. (if any) in the specification of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present application described herein can, for example, be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0127] It should be understood that in the present application, "at least one (item)" means one or more, and "plurality" means two or more. "And / or" is used to describe the association relationship of associated objects, indicating that three relationships may exist. For example, "A and / or B" can mean: only A exists, only B exists, and A and B exist at the same time, where A and B can be singular or plural. The character " / " generally indicates that the objects associated before and after are in an "or" relationship. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single or plural items. For example, at least one of a, b or c can mean: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", where a, b, c can be single or multiple.

[0128] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0129] In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0130] If the integrated unit is implemented in the form of 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 the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution can be embodied in the form of a software product. The computer software product is stored in a storage medium, including several instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk, etc. Various media that can store program codes.

[0131] As described above, the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for controlling switching of power modules of a reconfigurable converter, characterized in that: include: Collect the ambient temperature and electrical parameters of the reconfigurable converter; According to the electrical parameters, a power loss model of a key power device of the converter is constructed, wherein the power loss model is used to calculate the power loss parameters of the key power device of the converter; According to the power loss parameter, in combination with the ambient temperature and the thermal resistance parameter of the power device, a power device electrothermal model is constructed, wherein the power device electrothermal model is used to calculate the junction temperature parameter of the key power device of the converter; According to the junction temperature parameters, a relationship between the junction temperature parameters and the number of thermal cycle failures of the device is constructed through data fitting; Obtaining fatigue damage data of the power device according to the difference between the actual number of thermal cycles and the number of thermal cycle failures of the device; The switching configuration information of the power modules of the converter is determined according to the comparison result of the accumulated values ​​of fatigue loss data of each power device.

2. A method for controlling switching of power modules of a reconfigurable converter according to claim 1, characterized in that: The power loss model is specifically: ； ； ； ； In the formula, is the power loss parameter of the power device, is the conduction loss of key power devices, is the effective value of the current flowing through the device, is the on-resistance, is the turn-off loss or turn-on loss of the power device, is the power loss of key power devices, is the current when the power device is turned off or on, , are the turn-on energy loss and turn-off energy loss of the power device, is the load current, , , , , , are the coefficients of the corresponding constant term, linear term and quadratic term obtained by curve fitting, , They are the turn-on energy ratio and the turn-off energy ratio respectively.

3. A reconfigurable converter power module switching control method according to claim 1, characterized in that: The power device electrothermal model is specifically: ； In the formula, is the average junction temperature of the power device, is the power loss parameter of the power device, is the thermal resistance from the hot spot of the power device to the case, is the thermal resistance from the power device case to the thermal connection material, is the thermal resistance of the thermal connection material to the environment, is the ambient temperature.

4. A method for controlling switching of power modules of a reconfigurable converter according to claim 3, characterized in that: The methods for obtaining the junction temperature parameters include: Based on the power device electrothermal model, the thermal profile junction temperature data of the power device is obtained, and then based on the thermal profile junction temperature data, the average junction temperature and the junction temperature fluctuation are calculated by the rain flow counting method as the junction temperature parameter.

5. A method for controlling switching of power modules of a reconfigurable converter according to claim 3, characterized in that: The relationship between the junction temperature parameter and the number of thermal cycle failures of the device is specifically: ； In the formula, is the number of device thermal cycle failures, A and β are fitting coefficients, is the activation energy, is the Boltzmann constant, is the junction temperature fluctuation, is the average junction temperature.

6. A method for controlling switching of power modules of a reconfigurable converter according to claim 1, characterized in that: According to the difference between the actual number of thermal cycles and the number of thermal cycle failures of the device, the fatigue damage data of the power device is obtained, including: According to the ratio of the actual number of thermal cycles to the number of thermal cycle failures of the device, the fatigue damage data of the power device in this thermal cycle period is obtained.

7. A method for controlling switching of power modules of a reconfigurable converter according to claim 6, characterized in that: Determining the switching configuration information of the power modules of the converter according to the comparison result of the accumulated values ​​of fatigue loss data of each power device specifically includes: When the power module completes a charging task, the accumulated value of fatigue loss data of the power device is updated based on the fatigue damage data of the power device in previous thermal cycles; The switching configuration information of the power modules of the converter is determined according to the comparison result of the accumulated values ​​of fatigue loss data of each power device.

8. A reconfigurable converter power module switching control device, characterized in that: include: A parameter acquisition unit, used for collecting the ambient temperature and electrical parameters of the reconfigurable converter; A power loss model building unit, used to build a power loss model of a key power device of the converter according to the electrical parameters, wherein the power loss model is used to calculate the power loss parameters of the key power device of the converter; A device electrothermal model building unit, used to build a power device electrothermal model according to the power loss parameter, in combination with the ambient temperature and the thermal resistance parameter of the power device, wherein the power device electrothermal model is used to calculate the junction temperature parameter of the key power device of the converter; A cycle failure relationship building unit, used to build a relationship between the junction temperature parameter and the number of thermal cycle failures of the device through data fitting according to the junction temperature parameter; A fatigue damage data calculation unit, used to obtain fatigue damage data of the power device according to the difference between the actual number of thermal cycles and the number of thermal cycle failures of the device; The power module switching configuration determining unit is used to determine the power module switching configuration information of the converter according to the comparison result of the accumulated values ​​of fatigue loss data of each power device.

9. A reconfigurable converter power module switching control terminal, characterized in that: include: Memory and processor; The memory is used to store program codes, and the program codes are used to implement a switching control method for a power module of a reconfigurable converter according to any one of claims 1 to 7; The processor is used for reading and executing the program code.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores program codes, and the program codes are used to be read and executed by a processor to implement a reconfigurable converter power module switching control method as described in any one of claims 1 to 7.

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