| Due to the advantages of double-side cooling,high current density,and shortcircuit failure et.al of the Press-Pack Insulated Gate Bipolar Transistor(PP-IGBT)device,it is beneficial to satisfy the demand of high power devices for Voltage Source Converter based High Voltage Direct Current transmission(VSC-HVDC)converter valve equipment and becomes the first choice using in HVDC Modular Multilevel Converter(MMC)valve.However,the structure of the PP-IGBT device is different and more complex from the wire-bonded IGBT device,the internal layers of the PP-IGBT device are connected by external pressure.During the operation,the PP-IGBT device is not only affected by the electrical and thermal stress but also affected by the pressure,leading to more failure modes and more complex failure mechanisms.The fretting wear and short circuit failure are two failure modes with higher frequency in the PP-IGBT device,the failure process and lifetime of these two modes in the PP-IGBT device are related to the safety and reliability of application equipment.However,the existing analysis of these two modes is mainly based on data statistics and limited by the number of test samples,the failure mechanism of they is only studied under single stress,and the lifetime model of two modes adopts the classical mathematical model or the wirebonded IGBT lifetime model,it is not suitable for the PP-IGBT device.Thus,based on the failure of physical analysis,it is urgent to study the failure mechanism,failure evolution process,and reliability lifetime of the PP-IGBT device.Aiming at the problems that are difficult to extract the performance parameters,simulate the failure process,and built the reliability lifetime model of the PP-IGBT device during the aging process.Based on the actual 3300 V/50 A PP-IGBT device,this paper deeply studies the fretting wear and short circuit failure of the PP-IGBT device,establishes a multi-physics model that can modelling the failure process in the PP-IGBT device,carries out research on the failure process simulation and reliability lifetime assessment of the PP-IGBT device,and established the corresponding experiment to verify the results.At the same time,based on the operating conditions of the HVDC MMC valve,the reliability of the submodule in the converter valve is studied by using the PP-IGBT device,the failure rate analysis method of the submodule in the converter valve by considering the physical field failure simulation of the PP-IGBT device is proposed.The main research contents of this paper are as follows:(1)In terms of the multi-physics modeling method of PP-IGBT device,aiming at the problem that the packaging materials properties are affected by the temperature during the operation,a multi-physics modeling method of PP-IGBT device by considering the temperature effect of the packaging material is proposed,that is used to correct the current multi-physics model that is only considering the coupling of the electrical,thermal,and mechanical.Firstly,the influence of temperature on the thermal and electrical conductivity of packaging materials is analyzed,and the finite element simulation method by considering the change of material properties with different temperature is proposed.Secondly,the finite element model of the PP-IGBT device is proposed based on the material properties with temperature feedback and the multiphysics coupling of the electrical,thermal,and mechanical,that is used to compare the performances with the current multi-physics model under operation conditions.Finally,a different temperature current-voltage test platform and an infrared temperature test platform for the PP-IGBT device are established to verify the effectiveness of the proposed PP-IGBT device multi-physics model.(2)In terms of the fretting wear failure simulation of the PP-IGBT devices,based on the failure mechanism of the fretting wear failure in the PP-IGBT device,the fretting wear failure simulation method of the PP-IGBT device is proposed by considering the wear loss of the contact layers,it overcomes the problem that it is difficult to obtain the wear law of the contact layer surface and reliability assessment for the existing PPIGBT device.Firstly,a calculation method for fretting wear of each contact layer in the PP-IGBT device is proposed,and the influence of different working conditions on the wear of contact layer surface is analyzed.Secondly,a calculation and modeling method for the fretting wear and multi-physics coupling of thermal,mechanical for the PPIGBT device is proposed,the change rules of performance parameters and failure reasons during fretting wear failure of the PP-IGBT device are revealed,and the lifetime model of the PP-IGBT device is established by considering fretting fatigue of each contact layer in the device.Finally,the power cycling experiment platform is established to verify the rationality of the fretting wear model and effectiveness of the lifetime model of the PP-IGBT device.(3)In terms of the short circuit failure simulation of the PP-IGBT devices,based on the diffusion mechanism of aluminum and silicon under high temperature,the short circuit failure simulation of the PP-IGBT device is proposed by considering the osmotic hole with the aluminum and silicon,it is used to make up for the shortcomings of the existing short circuit failure test of the PP-IGBT device that is difficult to obtain the variation law of internal and external performance parameters.Firstly,based on molecular dynamics,the mechanism of aluminum and silicon mutual melting at high temperature is simulated,and the main factors and locations that cause the short circuit of the PP-IGBT are analyzed.Secondly,the electrical conductivity change rule of aluminum-silicon alloy under different failure degrees is calculated,a short circuit simulation model of 3300 V/50 A PP-IGBT device is established with an osmotic hole with aluminum and silicon,and the internal and external performance of the PP-IGBT device is analyzed under short circuit process.Finally,a short-circuit impact experiment platform of the PP-IGBT device is established to verify the effectiveness of the established short-circuit failure simulation method.(4)In terms of the reliability evaluation of the submodule using the PP-IGBT device in the converter valve,a failure rate evaluation method of the submodule by considering the multi-physics field failure simulation of the PP-IGBT device is proposed,it is used to improve the existing failure rate analysis method of the submodule using power devices by considering the constant failure rate model.Firstly,the converter valve time domain simulation model is established,that is used to extract the current of the PP-IGBT device.Secondly,the finite element simulation model of a3300 V/800 A PP-IGBT device is established,that is used to simulate the temperature change of the PP-IGBT device in the submodule under rectifier and inverter condition.Finally,the fault rate of the submodule with the multi-physics field failure simulation of Press-Pack IGBT is analyzed and compared with the constant failure rate model of the power device,and the influence of short-circuit durability and water cooling swing on the reliability of the MMC submodule is analyzed.The research results lay a theoretical foundation for failure evolution simulation and reliability evaluation of high voltage high power PP-IGBT devices,and also provide technical support for reliability analysis of high voltage high power PP-IGBT devices using in the submodule of the HVDC MMC. |
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