Converter reliability evaluation method and system and computer program product

Abstract

The invention discloses a converter reliability evaluation method and system and a computer program product. The method comprises the following steps: determining voltage data respectively corresponding to each sub-module in a plurality of module groups according to working condition information of a converter; based on the voltage data, establishing a loss model corresponding to each sub-module in the plurality of module groups, the loss model being used for determining operation loss of a plurality of components corresponding to each sub-module in the plurality of module groups; based on a loss model, calculating the steady-state junction temperature corresponding to each sub-module in the plurality of module groups; performing component failure rate analysis by using the steady-state junction temperature to obtain an analysis result; according to an analysis result, constructing a module reliability model corresponding to each sub-module in the plurality of module groups; and constructing a system reliability model based on the redundancy configuration strategy and the module reliability model. According to the invention, the technical problems of low accuracy and poor reliability of a converter reliability evaluation method in the prior art are solved.

Description

Technical Field

[0001] The present invention relates to the field of power electronics technology, and in particular to a converter reliability evaluation method, system and computer program product. Background Art

[0002] As a core component in power electronics technology, converters are widely used in energy generation, storage, and conversion fields such as electric vehicles, rail transit, and smart grids. Converter reliability assessment is one of the important means to conduct in-depth research on converter reliability and improve converter reliability. The related technologies mainly use calculation-based reliability assessment methods to assess the operating reliability of converters. However, due to the difficulty in conducting a detailed analysis of the losses of converter components, the reliability assessment results of the existing calculation-based reliability assessment methods have low accuracy and poor reliability.

[0003] To address the above-mentioned problems, no effective solution has been proposed yet. Summary of the invention

[0004] The embodiments of the present invention provide a method, system and computer program product for evaluating the reliability of a converter, so as to at least solve the technical problems of low accuracy and poor reliability of the method for evaluating the reliability of a converter in the related art.

[0005] According to one aspect of an embodiment of the present invention, a method for evaluating the reliability of a converter is provided, wherein the converter includes a plurality of module groups, each module group includes a plurality of sub-modules, each sub-module includes a plurality of converters, and each converter includes a plurality of components. The method includes: determining voltage data corresponding to each sub-module in the plurality of module groups according to operating information of the converter; establishing loss models corresponding to each sub-module in the plurality of module groups based on the voltage data, wherein the loss models are used to determine the operating losses of the plurality of components corresponding to each sub-module in the plurality of module groups; calculating the steady-state junction temperatures corresponding to each sub-module in the plurality of module groups based on the loss models; performing component failure rate analysis using the steady-state junction temperatures to obtain analysis results; constructing module reliability models corresponding to each sub-module in the plurality of module groups according to the analysis results; and constructing a system reliability model based on a redundant configuration strategy and the module reliability model, wherein the system reliability model is used to evaluate the operating reliability of the converter.

[0006] Optionally, the multiple converters in each submodule include a target resonant converter and a bidirectional boost-buck converter connected in cascade; the components in the target resonant converter include: a primary full bridge, a secondary full bridge, a primary resonant inductor, a secondary resonant inductor, a primary resonant capacitor, a secondary resonant capacitor, an excitation inductor, an input side DC support capacitor, an output side DC support capacitor and a high-frequency transformer, wherein the primary full bridge includes four first switching tubes and the secondary full bridge includes four second switching tubes; the components in the bidirectional boost-buck converter include: two third switching tubes, a transformer capacitor and a transformer inductor.

[0007] Optionally, according to the operating condition information of the converter, determining the voltage data corresponding to each sub-module includes: obtaining the operating condition information of the target resonant converter and the bidirectional boost-buck converter within a specified time range; calculating according to the operating condition information and the component characteristic information and circuit characteristic information corresponding to each sub-module to obtain voltage data, wherein the voltage data includes: the high-voltage side input voltage of the target resonant converter, the low-voltage side output voltage of the bidirectional boost-buck converter, and the inter-stage voltage between the target resonant converter and the bidirectional boost-buck converter.

[0008] Optionally, based on the voltage data, establishing loss models corresponding to each sub-module includes: determining the current effective value data and load current data of each sub-module based on the voltage data; using the current effective value data to calculate the conduction loss of each sub-module; using the load current data to calculate the switching loss of each sub-module; and summing the conduction loss and switching loss to obtain the loss model.

[0009] Optionally, based on the loss model, calculating the steady-state junction temperature corresponding to each sub-module includes: calculating the steady-state junction temperature based on the loss model and thermal network characteristic information corresponding to each sub-module, wherein the thermal network characteristic information is determined by the thermal resistance of multiple devices in each sub-module.

[0010] Optionally, the analysis results include the actual failure rates corresponding to each component in each sub-module; the component failure rate analysis is performed using the steady-state junction temperature, and the analysis results include: querying and determining the failure rate calculation formula, failure rate coefficient and basic failure rate corresponding to each component from the technical documents corresponding to the converter; and calculating the actual failure rate based on the steady-state junction temperature, failure rate calculation formula, failure rate coefficient, basic failure rate and effective life information of each component.

[0011] Optionally, based on the analysis results, constructing module reliability models corresponding to each sub-module includes: adding the actual failure rates according to the electrical connection structure of each sub-module to obtain the module reliability model, wherein the electrical connection structure is used to determine the correlation between the failure state of the components and the failure state of each sub-module.

[0012] Optionally, based on the redundant configuration strategy and the module reliability model corresponding to each sub-module in the converter, constructing a system reliability model includes: determining a target redundancy scheme corresponding to a target module group in the converter based on the redundant configuration strategy, wherein the target module group is any one of a plurality of module groups, and the target redundancy scheme is one of the following: an active redundancy scheme, a combination of active redundancy and passive redundancy; configuring redundant sub-modules for the target module group according to the target redundancy scheme, and updating the target module group; constructing a system reliability model based on the module reliability model corresponding to each sub-module in the updated converter.

[0013] According to another aspect of an embodiment of the present invention, a converter reliability assessment system is provided, including a memory and a processor, wherein a computer program is stored in the memory, and the processor is configured to run the computer program to execute any one of the above converter reliability assessment methods.

[0014] According to another aspect of an embodiment of the present invention, a computer program product is provided, including a computer program, and when the computer program is executed by a processor, the computer program implements any one of the above-mentioned converter reliability assessment methods.

[0015] In an embodiment of the present invention, the converter includes a plurality of module groups, each module group includes a plurality of submodules, each submodule includes a plurality of converters, each converter includes a plurality of components, and according to the working condition information of the converter, the voltage data corresponding to each submodule in the plurality of module groups is determined; based on the voltage data, a loss model corresponding to each submodule in the plurality of module groups is established, wherein the loss model is used to determine the operation loss of the plurality of components corresponding to each submodule in the plurality of module groups; based on the loss model, the steady-state junction temperature corresponding to each submodule in the plurality of module groups is calculated; the component failure rate is analyzed using the steady-state junction temperature to obtain the analysis result; according to the analysis result, the module reliability model corresponding to each submodule in the plurality of module groups is constructed; based on the redundant configuration strategy and the module reliability model, a system reliability model is constructed, wherein the system reliability model is used to evaluate the operation reliability of the converter. Thus, the present invention achieves the purpose of providing a more accurate converter reliability evaluation method, thereby achieving the technical effect of improving the accuracy and reliability of the converter reliability evaluation method, and thus solving the technical problem of low accuracy and poor reliability of the converter reliability evaluation method in the related art. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of this application. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0017] Figure 1 is a hardware structure block diagram of an optional terminal device for a method for evaluating converter reliability according to an embodiment of the present invention;

[0018] Figure 2 is a flow chart of a method for evaluating converter reliability according to an embodiment of the present invention;

[0019] Figure 3 is a circuit schematic diagram of a converter in an optional submodule according to an embodiment of the present application;

[0020] Figure 4 is a theoretical block diagram of an optional module reliability model according to an embodiment of the present application;

[0021] Figure 5 is a schematic diagram of an optional active redundancy solution according to an embodiment of the present application;

[0022] Figure 6 It is a schematic diagram of an optional active redundancy and passive easy combination solution according to an embodiment of the present application. DETAILED DESCRIPTION

[0023] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0024] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention 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 invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof 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.

[0025] According to an embodiment of the present invention, an embodiment of a method for evaluating the reliability of a converter is provided. It should be noted that the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer executable instructions, and although a logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in an order different from that shown here.

[0026] Figure 1 is a hardware structure block diagram of a terminal device for a converter reliability evaluation method according to an embodiment of the present invention, such as Figure 1 As shown, the terminal device may include one or more processors 102 (the processor 102 may include but is not limited to a processing device such as a microprocessor (Microcontroller Unit, referred to as MCU) or a programmable logic device (Field Programmable Gate Array, referred to as FPGA)), a memory 104 for storing data, and a transmission device 106 for communication functions. In addition, it may also include: a display device 110, an input / output device 108 (i.e., an I / O device), a Universal Serial Bus (USB) port (which may be included as one of the ports of a computer bus, not shown in the figure), a network interface (not shown in the figure), a power supply (not shown in the figure) and / or a camera (not shown in the figure). It can be understood by those skilled in the art that Figure 1 The structure shown is for illustration only and does not limit the structure of the above terminal device. Figure 1 More or fewer components as shown, or with Figure 1 Different configurations are shown.

[0027] It should be noted that the one or more processors 102 and / or other data processing circuits may be embodied in whole or in part as software, hardware, firmware or any other combination thereof. In addition, the data processing circuit may be a single independent processing module, or may be fully or partially integrated into any of the other components in the terminal device (or mobile device).

[0028] The memory 104 can be used to store software programs and modules of application software, such as the program instructions / data storage device corresponding to the converter reliability evaluation method in the embodiment of the present invention. The processor 102 executes various functional applications and data processing by running the software programs and modules stored in the memory 104, that is, the above-mentioned converter reliability evaluation method is realized. The memory 104 may include a high-speed random access memory, and may also include a non-volatile memory, such as one or more magnetic storage devices, flash memory, or other non-volatile solid-state memory. In some instances, the memory 104 may further include a memory remotely arranged relative to the processor 102, and these remote memories may be connected to the terminal device via a network. Examples of the above-mentioned network include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof.

[0029] The transmission device 106 is used to receive or send data via a network. The specific example of the above network may include a wireless network provided by a communication provider of the terminal device. In one example, the transmission device 106 includes a network adapter (Network Interface Controller, referred to as NIC), which can be connected to other network devices through a base station so as to communicate with the Internet. In one example, the transmission device 106 can be a radio frequency (Radio Frequency, referred to as RF) module, which is used to communicate with the Internet wirelessly.

[0030] Under the above operating environment, the embodiment of the present invention provides the following Figure 2 The converter reliability assessment method shown in Figure 2 is a flow chart of a method for evaluating converter reliability according to an embodiment of the present invention. Figure 2 As shown, the converter includes a plurality of module groups, each module group includes a plurality of submodules, each submodule includes a plurality of converters, each converter includes a plurality of components, and the method includes the following implementation steps:

[0031] Step S201, determining voltage data corresponding to each submodule in a plurality of module groups according to the operating condition information of the converter;

[0032] Step S202, based on the voltage data, establishing a loss model corresponding to each submodule in the plurality of module groups, wherein the loss model is used to determine the operation loss of a plurality of components corresponding to each submodule in the plurality of module groups;

[0033] Step S203, calculating the steady-state junction temperature corresponding to each submodule in the plurality of module groups based on the loss model;

[0034] Step S204, analyzing component failure rate using steady-state junction temperature to obtain analysis results;

[0035] Step S205, constructing module reliability models corresponding to each submodule in the plurality of module groups according to the analysis results;

[0036] Step S206: construct a system reliability model based on the redundant configuration strategy and the module reliability model, wherein the system reliability model is used to evaluate the operation reliability of the converter.

[0037] The above submodule may be the smallest functional unit in the converter that can operate independently. The above operating condition information may be state parameters of the converter under different operating conditions, such as input voltage, output voltage, current, frequency, etc. The above voltage data may include voltage values ​​of the high voltage side, interstage and low voltage side corresponding to each submodule. The above loss model may include conduction loss and switching loss.

[0038] The conduction loss can be determined by the on-resistance of the component and the current passing through. The switching loss can be determined by the switching frequency, the switching characteristics of the component (such as turn-on and turn-off losses) and the current level. The steady-state junction temperature can be the highest temperature of the submodule when it is running in a steady state, and the steady-state junction temperature can be used to assist in determining the life and reliability of the submodule.

[0039] The module reliability model can be constructed by calculating the total failure rate of the module. The redundant configuration strategy can be a strategy for adding a backup module to the reconfigurable converter system to cope with possible failures of the main module. By utilizing the redundant configuration strategy, it can be ensured that the system can still maintain basic functions when some components fail. The system reliability model can be used to evaluate the operating reliability of the converter under different working conditions.

[0040] Specifically, the operating condition information of the converter is obtained, the electrical characteristics of the circuit are analyzed, and the voltage data corresponding to each submodule in the multiple module groups under the corresponding operating conditions are calculated or measured. Further, according to the voltage data corresponding to each submodule in the multiple module groups, a loss model for determining the operating loss of multiple components corresponding to each submodule in the multiple module groups is established. Further, using the loss model corresponding to each submodule in the multiple module groups, the steady-state junction temperature corresponding to each submodule in the multiple module groups is calculated. Further, using the steady-state junction temperature corresponding to each submodule in the multiple module groups, the component failure rate is analyzed to obtain the analysis result of the component under specific operating conditions. Further, according to the failure rate of the component, combined with the connection logic (such as series connection, parallel connection) and working mode inside the module, the module reliability model corresponding to each submodule in the multiple module groups is constructed. Further, based on the redundant configuration strategy and the module reliability model corresponding to each submodule, a reliability model of the entire converter system is constructed.

[0041] It is easy to understand that, through the above steps S201 to S206, the embodiment of the present application can accurately evaluate the operating loss and steady-state junction temperature of multiple components corresponding to each submodule under different working conditions, thereby realizing quantitative analysis of the failure rate of components and constructing a system reliability model considering redundant configuration. Not only can the accuracy of the converter reliability assessment method for predicting the failure rate of components be improved, but also the overall operational reliability of the system can be improved through reasonable redundant design. Therefore, the converter reliability assessment method of the embodiment of the present application has higher accuracy and higher reliability.

[0042] The above method of the embodiment of the present invention is further introduced below.

[0043] Optionally, the above converter reliability assessment method may further include the following method steps:

[0044] Step S207, the multiple converters in each submodule include a target resonant converter and a bidirectional step-up and step-down converter connected in cascade;

[0045] Step S208, the components in the target resonant converter include: a primary full bridge, a secondary full bridge, a primary resonant inductor, a secondary resonant inductor, a primary resonant capacitor, a secondary resonant capacitor, an excitation inductor, an input side DC support capacitor, an output side DC support capacitor and a high-frequency transformer, wherein the primary full bridge includes four first switch tubes, and the secondary full bridge includes four second switch tubes;

[0046] Step S209, the components in the bidirectional step-up / step-down converter include: two third switch tubes, a transformer capacitor and a transformer inductor.

[0047] The above-mentioned cascade connection can be to connect two different circuits in series so that the output of one circuit becomes the input of another circuit. The above-mentioned target resonant converter can be a circuit that uses the resonance principle for power conversion. The above-mentioned bidirectional boost-buck converter can be a circuit that can realize voltage boost and buck functions, and the bidirectional boost-buck converter can be used to adjust the voltage level. The above-mentioned primary full bridge and secondary full bridge can be used to convert DC power supply into AC signal or convert AC power supply into DC signal. The above-mentioned excitation inductor can be used to provide a way to magnetize the transformer. The above-mentioned input side DC support capacitor can be used to stabilize the input voltage. The above-mentioned output side DC support capacitor can be used to stabilize the output voltage. The above-mentioned transformer capacitor and the above-mentioned transformer inductor can be used to adjust the operating point of the circuit to realize the voltage conversion function.

[0048] It is easy to understand that through the above steps S207 to S209, in the embodiment of the present application, by using a resonant converter, switching losses can be reduced and the overall efficiency of the system can be improved; by using a high-frequency transformer in the target resonant converter, not only can the electrical interference of the high-voltage side to the low-voltage side be prevented, but also the circuit can be protected from damage by the measured voltage; by utilizing a bidirectional boost-buck converter, the voltage can be adjusted according to load demand, bidirectional flow of energy can be achieved, and system flexibility is increased; by cascading two converters, the control strategy can be simplified, and precise control of voltage and current under different working conditions can be achieved.

[0049] Optionally, in the above step S201, determining the voltage data corresponding to each submodule according to the operating condition information of the converter may further include the following execution steps:

[0050] Step S2011, obtaining operating condition information of the target resonant converter and the bidirectional boost-buck converter within a specified time range;

[0051] Step S2012, calculate according to the operating condition information and the component characteristic information and circuit characteristic information corresponding to each sub-module to obtain voltage data, wherein the voltage data includes: the high-voltage side input voltage of the target resonant converter, the low-voltage side output voltage of the bidirectional boost-buck converter, and the inter-stage voltage between the target resonant converter and the bidirectional boost-buck converter.

[0052] The above-mentioned component characteristic information may be the physical properties and electrical characteristics of each component constituting the converter submodule, and the component characteristic information may include but is not limited to the on-resistance of the switch tube, the capacitance value of the capacitor, the inductance value of the inductor, the operating temperature range, and the rated power. The above-mentioned circuit characteristic information may be the structure, connection method, and working mode of the circuit, such as the resonant frequency of the target resonant converter, the transformation ratio of the transformer, the control strategy of the bidirectional boost-buck converter, etc. The above-mentioned high-voltage side input voltage may be the voltage entering the target resonant converter. The above-mentioned low-voltage side output voltage may be the voltage output to the load by the bidirectional boost-buck converter. The above-mentioned inter-stage voltage may be the voltage between the resonant converter and the boost-buck converter. The above-mentioned circuit characteristic information may be obtained by analyzing the circuit using circuit theory (such as Kirchhoff's laws and characteristic equations of circuit elements).

[0053] Specifically, by real-time monitoring of the target resonant converter and the bidirectional boost-buck converter, the operating condition information of the target resonant converter and the bidirectional boost-buck converter within a specified time range is obtained; further, the circuit characteristic information and component characteristic information of the target resonant converter and the bidirectional boost-buck converter are used, combined with the above-obtained operating condition information, to calculate the high-voltage side input voltage, low-voltage side output voltage and inter-stage voltage of each sub-module.

[0054] It is easy to understand that through the above steps S2011 to S2012, in the embodiment of the present application, by utilizing the operating condition information of the target resonant converter and the bidirectional boost-buck converter within a specified time range and the component characteristic information and circuit characteristic information corresponding to each sub-module, the voltage data of each sub-module can be accurately calculated, thereby effectively improving the accuracy of the converter reliability assessment method.

[0055] Optionally, in the above step S202, establishing the loss model corresponding to each submodule based on the voltage data may further include the following execution steps:

[0056] Step S2021, determining the current effective value data and load current data of each submodule based on the voltage data;

[0057] Step S2022, using the current effective value data, calculate the conduction loss of each submodule;

[0058] Step S2023, using the load current data, calculating the switching loss of each submodule;

[0059] Step S2024, summing up the conduction loss and the switching loss to obtain a loss model.

[0060] The above-mentioned effective value of current can be an important parameter to measure the actual effect of alternating current, and the effective value of current can represent the actual thermal effect of current. The above-mentioned conduction loss can be the energy loss caused by the on-resistance of the device when the component is in the on state. The above-mentioned load current data can be the current passing through the load or consumed by the load. The above-mentioned switching loss can be the energy loss generated by the switch tube during the opening and closing process.

[0061] Specifically, the current effective value and load current of each submodule are calculated based on the voltage data through a circuit analysis method (such as Kirchhoff's law, characteristic equation of circuit elements). Further, the conduction loss of each submodule is calculated according to the conduction loss calculation formula using the current effective value data. Further, based on the load current data, the switching loss of each submodule is calculated using the corresponding switching loss calculation formula. Further, the conduction loss and switching loss of each submodule are summed to obtain the total loss model of the submodule under specific working conditions.

[0062] It is easy to understand that through the above steps S2021 to S2024, in the embodiment of the present application, by establishing a loss model, the energy conversion efficiency of the converter under various operating conditions can be evaluated, and the thermodynamic behavior inside the converter can be more deeply understood, which can effectively improve the accuracy of the converter reliability evaluation method.

[0063] Optionally, in the above step S203, based on the loss model, calculating the steady-state junction temperature corresponding to each submodule may further include the following execution steps:

[0064] Step S2031, calculating the steady-state junction temperature based on the loss model and the thermal network characteristic information corresponding to each submodule, wherein the thermal network characteristic information is determined by the thermal resistance of multiple devices in each submodule.

[0065] The above-mentioned thermal network can be a model that simulates the transfer of heat in the system, and the thermal network can include the thermal resistance between each heat source (such as the loss heat source of the component) and the heat dissipation interface. The above-mentioned thermal resistance can be the resistance encountered when heat passes through the material or interface, and the thermal resistance can be used to represent the ratio of the temperature difference to the heat flow. The thermal resistance can include but is not limited to the thermal resistance of the component itself, the contact thermal resistance between components, and the thermal resistance between the component and the heat sink, radiator or the surrounding environment.

[0066] Specifically, based on the loss model and the thermal network characteristic information corresponding to each submodule, the temperature at which the heat generated by the loss of each submodule and the heat dissipated through the thermal resistance reach a balance under steady-state conditions is calculated to obtain the steady-state junction temperature.

[0067] It is easy to understand that through the above-mentioned step S2031, in the embodiment of the present application, the steady-state junction temperature is calculated based on the loss model and the thermal network characteristic information, which not only helps to accurately calculate the steady-state junction temperature of each sub-module, but also can assist in the evaluation of the operating reliability of the converter, thereby improving the accuracy of the converter reliability evaluation method.

[0068] Optionally, the analysis result includes the actual failure rate corresponding to each component in each submodule; in the above step S204, the component failure rate analysis is performed using the steady-state junction temperature, and obtaining the analysis result may also include the following execution steps:

[0069] Step S2041, querying and determining the failure rate calculation formula, failure rate coefficient and basic failure rate corresponding to each component from the technical document corresponding to the converter;

[0070] Step S2042, based on the steady-state junction temperature, the failure rate calculation formula, the failure rate coefficient, the basic failure rate and the effective life information of each component, the actual failure rate is calculated.

[0071] The above-mentioned technical document may be a document of detailed information of the converter, and the technical document may include converter system design, component selection and characteristics, circuit topology, working principle, control strategy, etc. The above-mentioned failure rate calculation formula may be a specific mathematical expression for calculating the failure rate of components, and the failure rate calculation formula may be used to quantify the failure probability of components. The above-mentioned failure rate coefficient may be a coefficient of the degree to which the failure rate of components is affected by different factors, and the failure rate coefficient may include temperature coefficient, usage coefficient, quality coefficient, environmental coefficient, electrical stress coefficient, contact structure coefficient, capacitance coefficient, etc. The above-mentioned basic failure rate may be the expected failure rate of components under standard working conditions, and the basic failure rate may be obtained from data provided by component manufacturers. The above-mentioned effective life information may be the expected service life of components under specific working conditions.

[0072] Specifically, the failure rate calculation formula, failure rate coefficient and basic failure rate corresponding to each component are queried from the technical documents corresponding to the converter. Further, based on the queried failure rate coefficient, combined with the actual working conditions and test results of the converter, the actual failure rate coefficient under actual working conditions is calculated. The actual failure rate coefficient, basic failure rate and steady-state junction temperature parameters obtained by the query and calculation are substituted into the failure rate calculation formula, and the actual failure rate of each component under the current working conditions is calculated in combination with the effective life information of the components.

[0073] It is easy to understand that through the above-mentioned steps S2041 to S2042, in the embodiment of the present application, by combining the steady-state junction temperature and detailed component characteristic parameters, the actual failure rate of the components can be calculated more accurately, which can provide data support for the fault prediction and maintenance strategy formulation of the converter, thereby improving the accuracy of the converter reliability assessment method.

[0074] Optionally, in the above step S205, based on the analysis results, constructing the module reliability model corresponding to each submodule may further include the following execution steps:

[0075] Step S2051, performing addition calculation on actual failure rates according to the electrical connection structures of the submodules to obtain a module reliability model, wherein the electrical connection structures are used to determine the correlation between the failure states of components and the failure states of the submodules.

[0076] The above electrical connection structure can be used to represent the electrical connection mode between components inside the sub-module, and the influence of the connection mode on the operating state of the sub-module.

[0077] Specifically, according to the design of each sub-module, the electrical connection structure of each sub-module is determined, and based on the electrical connection structure, the impact of the failure state of the components on the operating state of the sub-module is analyzed; further, the actual failure rates of all components in the sub-module are added to obtain the total failure rate of the sub-module, and the module reliability model is constructed by combining the total failure rate and the electrical connection structure of the sub-module.

[0078] It is easy to understand that, through the above step S2051, in the embodiment of the present application, by constructing a module reliability model, the reliability of the sub-module under different working conditions can be accurately evaluated, thereby improving the accuracy of the converter reliability evaluation method.

[0079] Optionally, in the above step S206, based on the redundant configuration strategy and the module reliability model corresponding to each submodule in the converter, constructing the system reliability model may further include the following execution steps:

[0080] Step S2061, determining a target redundancy scheme corresponding to a target module group in the converter based on a redundant configuration strategy, wherein the target module group is any one of the multiple module groups, and the target redundancy scheme is one of the following: an active redundancy scheme, a combination of active redundancy and passive redundancy scheme;

[0081] Step S2062, configuring redundant submodules for the target module group according to the target redundancy scheme, and updating the target module group;

[0082] Step S2063: construct a system reliability model based on the updated module reliability model corresponding to each submodule in the converter.

[0083] The target module group may be a module group selected for redundant configuration in the converter. The target redundancy scheme may be a redundant configuration strategy specifically implemented for the target module group. The redundant submodule may be a submodule additionally configured to improve system reliability.

[0084] Specifically, based on the redundant configuration strategy, a target module group is selected from multiple module groups, and a specific redundancy scheme to be implemented on the target module group is determined; further, according to the target redundancy scheme, redundant sub-modules are configured for the target module group. Since redundant sub-modules are configured in the target module group, the structure and connection method of the target module group will change, and the model of the target module group needs to be updated to reflect the new state after the redundant configuration; further, based on the module reliability model of each sub-module in the updated converter, a system reliability model of the entire converter system is constructed.

[0085] It should be noted that the above process of configuring redundant sub-modules for the target module group according to the target redundancy scheme may include steps such as determining the number of redundant sub-modules, determining the types of redundant sub-modules, and determining the connection method between the redundant sub-modules and the sub-modules in the existing module group.

[0086] It is easy to understand that through the above steps S2061 to S2063, in the embodiment of the present application, through the redundant configuration strategy, when a sub-module or module group fails, the redundant sub-module can be switched to ensure that the sub-module can operate normally, thereby improving the reliability and stability of the converter reliability evaluation scheme.

[0087] In an exemplary application scenario, Figure 3 FIG. 1 is a circuit diagram of a converter in an optional submodule according to an embodiment of the present application. Figure 3 As shown, the converter circuit in the submodule includes a circuit corresponding to a cascade-connected target resonant converter (referred to as a bidirectional resonant CLLC circuit) and a bidirectional step-up / step-down converter (referred to as a bidirectional Buck / Boost circuit), so that the high-side input voltage of the target resonant converter (referred to as V H ), the low-voltage side output voltage of the bidirectional step-up / step-down converter (denoted as V L ), and the interstage voltage between the target resonant converter and the bidirectional boost-buck converter (denoted as V M ).

[0088] The target resonant converter includes two symmetrical full bridges, two resonant inductors, two resonant capacitors, an excitation inductor, two DC support capacitors and a high-frequency transformer, wherein the transformation ratio is n, the primary H bridge includes switch tubes S1, S2, S3, and S4, the secondary H bridge includes switch tubes S5, S6, S7, and S8, and the primary resonant inductor is recorded as L r1 , the secondary resonant inductor is recorded as Lr2, and the primary resonant capacitor is recorded as C r1 , the secondary resonant capacitor is denoted as C r2 , the excitation inductance is recorded as L m , the DC support capacitor on the input side of the target resonant converter is denoted as C H , the DC support capacitor on the output side is C M .

[0089] The above-mentioned bidirectional step-up / step-down converter includes two switch tubes (respectively denoted as Q1 and Q2), a capacitor (represented as C L ) and inductance (denoted as L), where the high-voltage side input current is denoted as I H , the secondary output current is recorded as I M , the low voltage side output current is recorded as I L , the switching frequency is recorded as f s , the switching period is recorded as Ts .

[0090] For the bidirectional resonant CLLC circuit part, equation (1) can be obtained according to Kirchhoff's law and the characteristic equation of the circuit elements.

[0091]

[0092] In formula (1), represents the excitation current, represents the excitation current at time 0, represents the excitation voltage at time 0, represents the resonant current, represents the resonant current at time 0, Represents the resonant capacitor voltage at time 0, Indicates the voltage corresponding to the resonant inductance.

[0093] The resonant impedance Z in formula (1) r It can be calculated by formula (2).

[0094]

[0095] The angular frequency ω in formula (1) r It can be calculated by formula (3).

[0096]

[0097] According to the circuit characteristic information, equation (4) can be obtained.

[0098]

[0099] In formula (4), i s represents the secondary current, Represents the average secondary current, I turnoff Indicates the current when the switch is turned off.

[0100] The switching period T in formula (4) s It can be calculated by formula (5).

[0101]

[0102] From the above, we can get formula (6).

[0103]

[0104] In formula (6), i Lm (t0) represents the initial value of the excitation current, V Cr (t0) represents the initial value of the resonant voltage, C r Represents the full-bridge resonant capacitor.

[0105] For the bidirectional Buck / Boost circuit part, we can get equation (7) and equation (8).

[0106]

[0107] In formula (7), I L Represents the output current, I l represents the inductor current, input voltage V in =V M , output voltage V o =V L , duty cycle

[0108]

[0109] In formula (8), Represents the current flowing through the capacitor.

[0110] For the bidirectional resonant CLLC circuit part, the current effective value formula can be obtained by the above steps, that is, formula (9).

[0111]

[0112] In formula (9), I p_rms Represents the effective value of the primary current of the target resonant converter, I s_rms represents the effective value of the secondary current of the target resonant converter, i r1 Represents the primary resonant current.

[0113] The conduction loss can be calculated according to equations (10) and (11).

[0114]

[0115] In formula (10), P cond_p Represents the primary conduction loss, R ds(on)_p Represents the primary side on-resistance.

[0116]

[0117] In formula (11), P cond_s Represents the secondary side conduction loss, R ds(on)_s Represents the secondary side on-resistance.

[0118] For the bidirectional Buck / Boost circuit part, the above steps can yield equations (12), (13), (14), and (15).

[0119]

[0120] In formula (12), Pcond_Q1 represents the conduction loss of the switch tube Q1, R ds(on) represents the on-resistance of the switch tube, and T represents the switching period.

[0121]

[0122] In formula (13), P cond_Q2 Represents the conduction loss of the switch tube Q2.

[0123]

[0124] In formula (14), P L Indicates the inductor loss, ESR L Inductor equivalent series resistance, I l_rms Represents the effective value of the inductor current.

[0125]

[0126] In formula (15), Indicates capacitor loss, ESR C represents the capacitor equivalent series resistance, Indicates the effective value of capacitor current.

[0127] The switching loss can be expressed by a single switching loss model based on energy ratio, using energy ratio instead of the ratio of actual bus voltage to basic bus voltage to express the relationship between switching losses at different voltages. The above energy ratio is the ratio of the turn-on loss / turn-off loss at the actual DC bus voltage to the turn-on loss / turn-off loss at the basic bus voltage at a certain load current, and the energy ratio can be applied to a variety of load current conditions.

[0128] The specific steps are as follows: establish a double pulse test circuit, test a load current, the turn-on loss and turn-off loss of the actual bus voltage and the basic bus voltage, and obtain the turn-on energy ratio k based on the loss obtained by the actual bus voltage and the loss obtained by the basic bus voltage. on and the turn-off energy ratio k off Furthermore, by multiplying the switching loss under different load currents of the basic bus voltage by the energy ratio, the turn-on and turn-off loss corresponding to the actual bus voltage can be obtained.

[0129] According to the energy ratio model, the turn-on energy loss and turn-off energy loss can be calculated by formula (16).

[0130]

[0131] In formula (16), E MOSFET,ton Indicates the opening energy loss, E MOSFET,toff represents the turn-off energy loss, i load is the load current, A MOSFET,ton, B MOSFET,ton , C MOSFET,ton , A MOSFET,toff , B MOSFET,toff , C MOSFET,toff They represent the corresponding constant term, linear term and quadratic term coefficients obtained by curve fitting respectively.

[0132] Therefore, the switching loss can be calculated by equation (17).

[0133]

[0134] In formula (17), P sw,off / on represents the turn-off loss or turn-on loss, i off / on Indicates the current when turning off or on, E off / on It indicates the energy loss when the switch is turned off or the energy loss when it is turned on.

[0135] By summing up the conduction loss and switching loss, the corresponding loss model can be established.

[0136] The reliability evaluation premise is that the failure rate-time curve of the electrical device is in the effective life period. The failure rate of the electrical device in the effective life period is approximately regarded as a constant, and the reliability function obeys the exponential distribution, as shown in formula (18).

[0137] R(t)=e -λt Formula (18)

[0138] In formula (18), R(t) represents the reliability function and λ represents the failure rate.

[0139] The actual failure rate of the component is denoted as λ p , the basic failure rate is recorded as λ b , the failure rate coefficient is recorded as π, then we can get equations (19) and (20).

[0140]

[0141] In formula (19), π i Indicates the failure rate coefficient of each component, including: π T represents the temperature coefficient, π A Indicates the utilization factor, π Q Denotes the quality coefficient, π E represents the environmental factor, π S represents the electrical stress coefficient, π C represents the contact structure coefficient, π CV Indicates the capacitance coefficient. Depending on the type of component, the type of failure rate coefficient included is also different.

[0142]

[0143] In formula (20), λ M,b represents the basic failure rate of the CLLC primary switch MOSFET, λ C,b represents the basic failure rate of capacitors, π V represents the voltage coefficient, π SR Represents the resistivity, λ L,b represents the basic failure rate of inductance, λ Tran,b Indicates the basic failure rate of transformer.

[0144] In an exemplary application scenario, Figure 4 is a theoretical block diagram of an optional module reliability model according to an embodiment of the present application. Figure 4 As shown, it can be seen that the submodule belongs to a reliability system connected in series. According to the cascade structure and working principle of the sub-power module CLLC resonant converter and the bidirectional Buck / Boost converter, each device in the submodule is a component of the conduction loop under a specific working state. Therefore, the failure of any device will cause the failure of the entire submodule, which is specifically shown as follows Figure 2 From the LEVEL4 part of , we can get formula (21).

[0145]

[0146] In formula (21), λ CLLC represents the target resonant converter failure rate, λ BUCK represents the failure rate of the bidirectional boost-buck converter, λ Mp represents the failure rate of the CLLC primary switch MOSFET, λ Ms Indicates the failure rate of the MOSFET on the secondary side of the CLLC, represents the failure rate of DC link capacitor, λ Cr1 , Cr2 represents the failure rate of the resonant capacitor, λ Lr1 λ Lr2 represents the resonant inductance failure rate, λ Lm represents the excitation inductance failure rate, λ Tran represents the transformer failure rate, λ Q1 λ Q2 Indicates the failure rate of the Buck circuit switch tube, and λ L Indicates the failure rate of capacitor and inductor in the Buck circuit.

[0147] Thus, we can obtain formula (22).

[0148]

[0149] In formula (22), λ SM Indicates the submodule failure rate.

[0150] In an optional exemplary application scenario, the inverter is applied to an electric vehicle DC fast charging station scenario as an adaptive reconfigurable charging stack, which consists of a grid DC bus, a high-voltage switch array, n power modules, m low-voltage switch arrays and m charging guns, wherein each charging gun needs to be configured with a low-voltage switch array, and the low-voltage switch arrays are connected in parallel. The charging gun can be configured with multiple modules, and the configured basic number of modules can be used to meet the minimum requirements for EV charging, that is, all basic modules are connected in series to meet the maximum charging voltage requirement, and the maximum number of modules configured for the charging gun can be determined by the peak power designed for the charging gun.

[0151] Inside the charging stack, the DC bus and the charging gun are connected through a DC-DC power module to adjust the electrical energy to the voltage and current required for charging the electric vehicle. The range of each gun access module is determined based on the rated power of the module and the maximum power that the charging gun can support, so that the number of switches in the corresponding low-voltage switch array can be simplified. In order to simplify the design of the low-voltage side switch array, the series switch is set between two adjacent modules to achieve series connection between adjacent modules.

[0152] Furthermore, in order to improve the utilization rate of modules and reduce the probability that idle modules cannot be connected to the charging gun in series, it is necessary to optimize the switching mode of power modules. Since the series switch is set between two adjacent modules, redundancy is considered in groups to improve system reliability. Specifically, let the number of basic modules configured for each charging gun be q, and the total number of modules configured for the charging stack be mm, where mm can be a multiple of q. All modules are sorted, with each q modules as a group. The series connection is only reconstructed between modules in each group, while the parallel connection can be reconstructed both within and between groups. The system is provided with n modules and m charging guns. Each charging gun is equipped with q basic modules, so there are m groups of basic module groups and r=n / qm groups of redundant module groups.

[0153] Figure 5 is a schematic diagram of an optional active redundancy solution according to an embodiment of the present application, such as Figure 5 As shown, the redundant module works normally like other modules. When a basic module group finds a fault, it can be replaced by the redundant module group. There are m+r module groups in total. The system can work normally only when at least m module groups work normally.

[0154] Figure 6 is a schematic diagram of an optional active redundancy and passive redundancy combination solution according to an embodiment of the present application, such as Figure 6As shown in the figure, since the basic module group is used more frequently than the redundant module group, the actual failure rate of the basic module group is higher. Therefore, on the basis of the active redundancy solution, a passive redundant module is equipped in the basic module group to form an active redundancy and passive easy combination solution. The passive redundant module is bypassed during normal operation, and the passive redundant module is switched to the running state only when a faulty module appears in the basic module group.

[0155] In an exemplary application scenario, Figure 2 As shown by Figure 2 From LEVEL2 in the figure, it can be seen that the module group failure rate can be calculated by formula (23).

[0156] λ set =qλ SM Formula (23)

[0157] like Figure 5 As shown in the figure, since active redundancy and passive redundancy are easy to combine, the basic module group redundancy mode is passive redundancy, which can be described by gamma distribution: it consists of q independent modules with the same failure rate λ SM The reliability of a module group composed of modules will be subject to the parameter qλ SM The exponential distribution of exponential distribution has no memory. After each fault switching, the new sub-module combination still obeys the parameter qλ. SM exponential distribution, assuming that the system has q+s (k≤n) submodules, of which s submodules are redundant submodules. When s+1 failures occur, the system exits operation. Therefore, the whole process is subject to the scale parameter qλ SM , the gamma distribution with shape parameter s, its reliability function R(q,q+s,t) is shown in formula (24), and the mean time to failure MTTF is shown in formula (25). The system failure rate in this redundancy scheme is As shown in formula (26).

[0158]

[0159] For systems considering redundant configuration, there are three states: no fault, partial fault, and complete fault. In the case of partial fault, the system can still work normally, while in the case of complete fault, the system will stop running. If any of the m charging guns fails, it is recorded as a complete system failure. According to the redundancy strategy, the state transfer matrix is ​​generated and the corresponding probability equation is obtained. The state transfer matrix A is a square matrix of S×S, where S is the number of states in the state transfer diagram, and the element a in the matrix is i,j represents the transition rate from state i to state j.

[0160] If the active redundancy scheme is adopted, the state transfer matrix can be expressed by equation (27).

[0161]

[0162] Combining formula (28) we can get the corresponding probability equation, as shown in formula (29).

[0163]

[0164] In formula (28), P(t) = (P0(t), P1(t), ...) represents the state vector, and P(0) = (P0(0), P1(0), ...) represents the initial state of the system.

[0165]

[0166] In formula (29), P i (t) represents the probability that the system is in state i at time t, λ set,0 ,λ set,1 …λ set,r Indicates the failure rate of the power module group.

[0167] If the active redundancy and passive redundancy are combined, the state transfer matrix can be expressed by equation (30). Similarly, the corresponding probability equation can be obtained, and then the corresponding reliability evaluation index can be obtained, the reliability function R sys (t) = 1-P s (t), where P s (t) represents the probability of being in fault state s, R sys (t) represents the reliability function of the system. Mean time between failures, B10 life: corresponds to the time point when the reliability function is equal to 0.9.

[0168]

[0169] In another application scenario of reconfigurable converters, in order to evaluate the reliability of reconfigurable converters and design appropriate and effective redundancy strategies, the reconfigurable converter system under the following working conditions is evaluated: V H :750VV M :500VV L : 350V, I L The reconfigurable converter system has 12 submodules and 2 charging guns, each equipped with 2 basic modules. The high-voltage side switch tubes S1-S4 of the target resonant converter use CREE's C2M0080170P silicon carbide MOSFET, and the low-voltage side switch tubes S5-S8 of the target resonant converter and the third switch tubes Q1-Q2 of the bidirectional boost-buck converter use C3M0030090K. The DC support capacitor uses a metal film capacitor, and the resonant capacitor uses a ceramic chip capacitor. The ambient temperature Ta = 25°C.

[0170] Combining the above content, we can get p_rms =30.508A, I s_rms =45.508A. Further, taking the calculation of the high-voltage side switch tube S1-S4 of the target resonant converter as an example, the conduction loss of the component MOSFETS1-S4 is calculated: P cond_p =46.538W, turn-off loss: E off =0.002I d 3 +-0.051I d 2 +0.622I d +41.443, P sw,off =1.5W, P loss It is about 48W, and the junction temperature is about 50℃. The failure rate is 0.155*10-6 times / h, which means the equivalent annual failure rate is 0.00136 times / year.

[0171] Similarly, the failure rate of each component can be obtained, as shown in Table 1.

[0172] Table 1

[0173] Components General failure rate (times / h) quantity Equivalent annual failure rate (times / year) MOSFET S1-S4 <![CDATA[0.155×10 -6 ]]> 4 0.00136 MOSFET S5-S8 <![CDATA[0.151×10 -6 ]]> 4 0.00132 DC side support capacitor C <![CDATA[0.598×10 -6 ]]> 3 0.005238 Resonant capacitor <![CDATA[0.205×10 -6 ]]> 2 0.001796 Resonant Inductor <![CDATA[0.01199×10 -6 ]]> 2 0.000105 transformer <![CDATA[0.82×10 -6 ]]> 1 0.00715 MOSFET Q1 <![CDATA[0.276×10 -6 ]]> 1 0.00242 MOSFET Q2 <![CDATA[0.148×10 -6 ]]> 1 0.00130 inductance <![CDATA[0.0011×10 -6 ]]> 1 0.00011

[0174] From the above content, we can get formula (31).

[0175]

[0176] Combining formula (31), the submodule failure rate can be obtained, as shown in formula (32).

[0177] λ SM =λ CLLC +λ BUCK Formula (32)

[0178] According to formula (32), it can be calculated that the submodule failure rate is equal to 0.4696.

[0179] It can be obtained that the submodule reliability function R SM (t) = e -0.2348t , the charging gun corresponds to the failure rate λ set =2λ SM =0.4696. When the charging gun fails, it is a system failure. When no redundant configuration is performed, the corresponding system failure rate is λ sys =2λ set =0.9692, mean time to failure MTTF =1.0318.

[0180] If the active redundancy scheme is adopted (denoted as redundancy scheme 1), equations (33) and (34) can be obtained.

[0181]

[0182] Combining equations (33) and (34), we can calculate that the mean time to failure (MTTF) = 3.0877 and the equivalent failure rate is 0.3239.

[0183] If a scheme combining active redundancy and passive redundancy is adopted (denoted as redundancy scheme 2), equations (35) and (36) can be obtained.

[0184] Combining equations (33) and (34), we can calculate that the mean time to failure (MTTF) = 4.0375 and the equivalent failure rate of the system is 0.2477.

[0185]

[0186]

[0187] In formula (36), λ setg represents the basic module group failure rate, λ setf Indicates the failure rate of the redundant module group.

[0188] Thus, the reliability evaluation index result table can be obtained, as shown in Table 2.

[0189] Table 2

[0190]

[0191] According to the content in Table 2, it can be seen that when no redundant configuration is performed, the corresponding failure rate of the system is the highest. After the redundant configuration is adopted, the corresponding failure rate of the system decreases. Among them, the combination of active redundancy and passive redundancy is more effective in reducing the system failure rate than the active redundancy solution. The combination of active redundancy and passive redundancy has the best effect on reducing the system failure rate.

[0192] In an embodiment of the present invention, the converter includes a plurality of module groups, each module group includes a plurality of submodules, each submodule includes a plurality of converters, each converter includes a plurality of components, and according to the working condition information of the converter, the voltage data corresponding to each submodule in the plurality of module groups is determined; based on the voltage data, a loss model corresponding to each submodule in the plurality of module groups is established, wherein the loss model is used to determine the operation loss of the plurality of components corresponding to each submodule in the plurality of module groups; based on the loss model, the steady-state junction temperature corresponding to each submodule in the plurality of module groups is calculated; the component failure rate is analyzed using the steady-state junction temperature to obtain the analysis result; according to the analysis result, the module reliability model corresponding to each submodule in the plurality of module groups is constructed; based on the redundant configuration strategy and the module reliability model, a system reliability model is constructed, wherein the system reliability model is used to evaluate the operation reliability of the converter. Thus, the present invention achieves the purpose of providing a more accurate converter reliability evaluation method, thereby achieving the technical effect of improving the accuracy and reliability of the converter reliability evaluation method, and thus solving the technical problem of low accuracy and poor reliability of the converter reliability evaluation method in the related art.

[0193] According to another aspect of an embodiment of the present invention, a converter reliability assessment system is provided, comprising a memory and a processor, wherein a computer program is stored in the memory, and the processor is configured to run the computer program to execute any one of the above converter reliability assessment methods.

[0194] Optionally, in this embodiment, the processor may be configured to perform the following steps through a computer program: determining voltage data corresponding to each submodule in a plurality of module groups according to operating condition information of the converter; establishing loss models corresponding to each submodule in a plurality of module groups based on the voltage data, wherein the loss models are used to determine operating losses of a plurality of components corresponding to each submodule in a plurality of module groups; calculating steady-state junction temperatures corresponding to each submodule in a plurality of module groups based on the loss models; performing component failure rate analysis using the steady-state junction temperatures to obtain analysis results; constructing module reliability models corresponding to each submodule in a plurality of module groups according to the analysis results; and constructing a system reliability model based on the redundant configuration strategy and the module reliability model, wherein the system reliability model is used to evaluate the operating reliability of the converter.

[0195] According to another aspect of the embodiments of the present invention, there is further provided a computer program product, comprising a computer program, wherein when the computer program is executed by a processor, the computer program implements any one of the above-mentioned methods for evaluating the reliability of a converter.

[0196] Optionally, the specific examples in this embodiment may refer to the examples described in the above embodiment and its optional implementation manners, which will not be described in detail here.

[0197] The serial numbers of the above embodiments of the present invention are for description only and do not represent the advantages or disadvantages of the embodiments.

[0198] In the above embodiments of the present invention, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0199] In the several embodiments provided in this application, it should be understood that the disclosed technical content can be implemented in other ways. Among them, the device embodiments described above are only schematic. For example, the division of the units can be a logical function division. There may be other division methods in actual implementation. For example, 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 through some interfaces, indirect coupling or communication connection of units or modules, which can be electrical or other forms.

[0200] 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 units. Some or all of the units may be selected according to actual needs to achieve the purpose of the present embodiment.

[0201] 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.

[0202] 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, server or 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: various media that can store program codes, such as USB flash drives, ROM, RAM, mobile hard disks, magnetic disks or optical disks.

[0203] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for evaluating converter reliability, characterized in that: The converter includes a plurality of module groups, each module group includes a plurality of submodules, each submodule includes a plurality of converters, each converter includes a plurality of components, and the converter reliability evaluation method includes: Determining voltage data corresponding to each submodule in the plurality of module groups according to the operating condition information of the converter; Based on the voltage data, establishing a loss model corresponding to each submodule in the plurality of module groups, wherein the loss model is used to determine the operation loss of a plurality of components corresponding to each submodule in the plurality of module groups; Based on the loss model, calculating the steady-state junction temperature corresponding to each submodule in the plurality of module groups; Utilizing the steady-state junction temperature to analyze component failure rates and obtain analysis results; According to the analysis results, construct module reliability models corresponding to each submodule in the plurality of module groups; Based on the redundant configuration strategy and the module reliability model, a system reliability model is constructed, wherein the system reliability model is used to evaluate the operational reliability of the converter.

2. The method for evaluating converter reliability according to claim 1, characterized in that: The multiple converters in each submodule include a target resonant converter and a bidirectional boost-buck converter connected in cascade; The components in the target resonant converter include: a primary full bridge, a secondary full bridge, a primary resonant inductor, a secondary resonant inductor, a primary resonant capacitor, a secondary resonant capacitor, an excitation inductor, an input side DC support capacitor, an output side DC support capacitor and a high-frequency transformer, wherein the primary full bridge includes four first switch tubes, and the secondary full bridge includes four second switch tubes; The components in the bidirectional step-up and step-down converter include: two third switch tubes, a transformer capacitor and a transformer inductor.

3. The method for evaluating converter reliability according to claim 2, characterized in that: Determining, according to the operating condition information of the converter, the voltage data corresponding to each of the submodules includes: Acquiring the operating condition information of the target resonant converter and the bidirectional boost-buck converter within a specified time range; The voltage data is obtained by calculating according to the operating condition information and the component characteristic information and circuit characteristic information corresponding to each submodule, wherein the voltage data includes: the high-voltage side input voltage of the target resonant converter, the low-voltage side output voltage of the bidirectional boost-buck converter, and the inter-stage voltage between the target resonant converter and the bidirectional boost-buck converter.

4. The method for evaluating converter reliability according to claim 1, characterized in that: Based on the voltage data, establishing the loss models corresponding to the respective submodules includes: Based on the voltage data, determining the current effective value data and the load current data of each submodule; Using the current effective value data, the conduction loss of each submodule is calculated; Calculating the switching loss of each submodule using the load current data; The conduction loss and the switching loss are summed up and calculated to obtain the loss model.

5. The method for evaluating converter reliability according to claim 1, characterized in that: Based on the loss model, calculating the steady-state junction temperatures corresponding to each of the submodules includes: The steady-state junction temperature is calculated based on the loss model and the thermal network characteristic information corresponding to each of the submodules, wherein the thermal network characteristic information is determined by thermal resistances of multiple devices in each of the submodules.

6. The method for evaluating converter reliability according to claim 1, characterized in that: The analysis results include actual failure rates corresponding to the components in each submodule; The steady-state junction temperature is used to analyze the failure rate of components, and the analysis results include: Search and determine the failure rate calculation formula, failure rate coefficient and basic failure rate corresponding to each component from the technical document corresponding to the converter; The actual failure rate is calculated based on the steady-state junction temperature, the failure rate calculation formula, the failure rate coefficient, the basic failure rate and the effective life information of each component.

7. The method for evaluating converter reliability according to claim 6, characterized in that: According to the analysis results, constructing the module reliability models corresponding to the submodules respectively includes: The actual failure rates are added up according to the electrical connection structures of the submodules to obtain the module reliability model, wherein the electrical connection structure is used to determine the correlation between the failure state of the components and the failure state of the submodules.

8. The method for evaluating converter reliability according to claim 1, characterized in that: Based on the redundant configuration strategy and the module reliability model corresponding to each submodule in the converter, constructing the system reliability model includes: Determine a target redundancy scheme corresponding to a target module group in the converter based on the redundant configuration strategy, wherein the target module group is any one of the multiple module groups, and the target redundancy scheme is one of the following: an active redundancy scheme, a combination of active redundancy and passive redundancy scheme; According to the target redundancy scheme, redundant submodules are configured for the target module group, and the target module group is updated; The system reliability model is constructed based on the updated module reliability model corresponding to each submodule in the converter.

9. A converter reliability assessment system, characterized in that: It comprises a memory and a processor, wherein the memory stores a computer program, and the processor is configured to run the computer program to execute the converter reliability assessment method according to any one of claims 1 to 8.

10. A computer program product, characterized in that The invention comprises a computer program, which implements the converter reliability assessment method according to any one of claims 1 to 8 when being executed by a processor.

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