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关键词： 开关磁阻电机   直接瞬时转矩   转矩脉动   转矩分配函数   直接转矩控制  

摘要： 开关磁阻电机具有起动转矩大,调速性能好,但是转矩、磁链具有非线性特性的特点。这些特性形成了转矩脉动大的特点,这个特点限制了开关磁阻电机的应用。本文将结合转矩运行的特点,介绍常见的转矩控制方法直接瞬时转矩控制法、转矩分配函数法、直接转矩控制等方法,并且进行了分析,指出不同方法的优劣,为开关磁阻电机的转矩研究提供参考依据。

关键词： 电机抖动   变频器   电容老化   频率设定信号  

摘要： 电机抖动是变频驱动系统中影响运行稳定性与设备寿命的常见问题。在系统梳理控制参数参数设置、供电质量、机械结构等常规诱因及应对策略的基础上,进一步分析了两类在工程实践中易被忽视但影响显著的特殊成因。一方面,深入探讨了直流母线电容老化在高频运行状态下引发电压支撑能力下降,导致转矩扰动进而引起电机抖动的机理,分析了影响电容劣化的主要因素,并提出相应处置和预防措施。另一方面,对频率信号异常引发抖动的机理进行了分析,结合电位器老化磨损问题,提出临时参数调整与部件更换的应急策略。为提升故障排查效率,构建了逐层递进的诊断流程。研究成果可为电机系统运维提供针对性的理论支撑与实用指导。

关键词： Conformable分数阶导数   分数阶发展包含   紧算子半群   最优控制   不动点定理  

摘要： 用Bohnenblust-Karlin不动点定理得到了Conformable分数阶发展包含mild解的存在性,并利用两次构造极小化序列的方法分别讨论了最优状态控制对和最优时间控制对的存在性.通过一个具体例子验证了结论的有效性.

关键词： Effective thermal cycle   Accurate damage and fatigue life prediction   Fatigue life of IGBT power module   Critical damage parameters   Solder fatigue life models  

摘要： Insulated gate bipolar transistor (IGBT) power module is vital to efficient functioning of several critical systems in electric vehicle (EV), photovoltaic (PV) module, and more/all electric aircrafts (MEA/AEA). As reliability qualification of IGBT immensely depends on system's modelling which employs thermal cycling, identification of effective number of accelerated thermal cycles (ATCs) is important to ensure accurate reliability prediction. This investigation advises on the effective number of ATCs for modelling damage and fatigue life of 96.5 % tin, 3 % silver, and 0.5 % copper (SAC305) solder joints in IGBT module. SolidWorks software is used to create four realistic 3-D finite element (FE) models of typical IGBT module. The IEC 60068-2-14 thermal cycle test and Anand's time independent visco-plastic constitutive model are implemented in static structural package in ANSYS mechanical software to simulate the response of the models to 6 ATCs, 12 ATCs, 18 ATCs and 24 ATCs. Thirty ATCs produced magnitudes of von-Mises stress, equivalent plastic strain and accumulated strain energy density which are almost invariant with application of greater number of ATC. Deployment of four fatigue life constitutive equations from Morrow, Coffin-Manson, and Syed generated polynomial model which produced minimum and consistent lives of the IGBT modules at about 30 ATCs. Based on this finding, 30 ATCs are proposed as the effective number. The generated models establish the relationship between the number of ATCs and fatigue life predicted for IGBT module. It is proposed to be used to evaluate the effect of number of ATCs employed and the resultant predicted fatigue life of IGBT module.

关键词： Insulated gate bipolar transistors   Junctions   Finite element analysis   Accuracy   Computational modeling   Heating systems   Temperature distribution   Temperature sensors   Real-time systems   Predictive models   Galerkin projection   insulated-gate bipolar transistor (IGBT)   junction temperature   reduction thermal model   traction converter  

摘要： The insulated-gate bipolar transistor (IGBT) module is a critical component of the traction converter in rail transit vehicles, and its reliability is essential for the safe operation of these vehicles. Junction temperature is a key parameter affecting the performance and reliability of IGBTs. Existing onboard traction converters lack effective methods for real-time monitoring of the IGBT module's junction temperature. To address this issue, this article proposes a reduction thermal modeling approach based on Galerkin projection for real-time assessment of the junction temperature in IGBT modules. The high-order heat conduction equations can be projected into a subspace by only inputting the converter's IGBT module's convection coefficient and power loss and utilizing an eigenvalue decomposition method based on singular value decomposition (SVD) to extract basis vectors. This allows for generating a thermal field temperature map of the IGBT chip without additional external circuits or sensors, facilitating real-time and accurate evaluation of the IGBT module's junction temperature. Finally, a power cycling experimental platform for the IGBT module was established, and comparative experiments under various operating conditions were conducted. The experimental results validate the real time and accuracy of the proposed method for assessing the junction temperature of IGBT modules.

关键词： IGBT power module   operating ambient conditions   solder joint degradation   power electronics   lead-free SAC305 solder  

摘要： Insulated gate bipolar transistor (IGBT) power modules experience power and thermal cycles in field operation which significantly degrade their solder joints, leading to reduced designed life. This investigation evaluates mechanical reliability of an IGBT power module in four key applications to provide new knowledge on the impact of ambient temperatures on the degradation of its solder joints and fatigue life. SolidWorks software is used to create eight 3-D computer-aided design (CAD) models of a typical IGBT module. Power load, induced by field operation, and IEC 60068-2-14 accelerated thermal cycle (ATC) specific to aeronautics, automotive passenger compartment, automotive under-the-hood and railway applications are used as loads. The loads and Anand's visco-plastic model are implemented in the static structural solver within the Ansys mechanical package to simulate the degradation of 96.5% tin, 3.0% silver, and 0.5% copper (SAC305) solder joints in the modules. Aeronautic ambient temperature degrades solder joints in an IGBT power module the most, while railway ambient temperature degrades it the least. Consequently, the module has the shortest average fatigue life of 7.5 years and longest average life of 16.2 years in operations in aeronautic and railway ambient temperatures, respectively. In comparison with operation in the aeronautic condition, the module operates 36.0% and 85.3% longer life in auto under-the-hood and auto passenger ambient temperatures, respectively. Implementation of obtained laboratory test cycles in predicting the field fatigue lives of the modules in years is presented. Stress damage is found to concentrate at the periphery of solder joints which is the area to strengthen to improve device reliability. This study provides new knowledge on the deployment of an IGBT power module in four critical applications.

关键词： Switches   Voltage control   Control systems   Limiting   Insulated gate bipolar transistors   Thyristors   Arresters   Power systems   Energy consumption   Threshold voltage   Bypass switch   controllable arrester   IGBT   voltage suppression and energy consumption  

摘要： As the power system develops toward larger capacity and greater integration of new energy sources, the proportion of sensitive equipment such as power electronic converters is increasing, resulting in a heightened need for overvoltage suppression. The controllable arrester (CA), as a novel device capable of achieving deep overvoltage suppression, has gained significant attention. However, the use of semicontrolled switches in CAs often results in difficulties with exiting after activation in dc systems, leading to excessive energy absorption and limited suppression capability. This article proposes a novel controllable arrester with flexible operation (Flexible CA) for dc transmission systems. By integrating a fully-controlled switch with the existing semicontrolled switch, the Flexible CA enables both rapid operation and flexible exit capabilities, while also decoupling overvoltage suppression from energy absorption. Detailed parameter configuration and working strategies allow for improved performance in overvoltage suppression and energy management. Finally, 2 kV and 25 kV prototypes of Flexible CA and overvoltage suppression experimental platforms have been developed to validate the feasibility of the proposed design. In addition, a +/- 500 kV/3000 MW offshore VSC-HVdc simulation system with the Flexible CA has been also established. The results demonstrated effective decoupling of overvoltage suppression from energy consumption, limiting overvoltage to 1.6 p.u. while reducing excess energy demand by at least 54.1%, with better techno-economic performance.

关键词： Fault diagnosis   fault location   neural networks   three-phase dc-ac inverters   fault location   neural networks   three-phase dc-ac inverters  

摘要： This article presents a novel fault diagnosis method for open-circuit faults of insulated gate bipolar transistors (IGBTs) and current sensor faults in three-phase sinusoidal pulsewidth modulation inverters. The proposed method facilitates the simultaneous diagnosis of multiple IGBT and current sensor faults. A combination of Park transform and fast Fourier transform (FFT) is employed to extract fault features. The Park transform converts three-phase current into two-phase current, thereby reducing the dimensionality of the data. The FFT integrates time-domain and frequency-domain analyses to enhance the representation of fault characteristics. Additionally, fault features are extracted from the samples post-FFT to minimize the data volume of individual sample input by the model. For fault diagnosis, a temporal convolutional neural network model incorporating stacked residual blocks is developed to train and evaluate potential faults and demonstrate the model's validity and accuracy. The results of online simulations and hardware-in-the-loop experiments indicate that the proposed method can identify and locate the IGBT and sensor faults within 32 ms, and the accuracy is 98.75%. This method achieves higher training and testing accuracy and faster training and testing speed, which is superior to the existing diagnosis technologies.

关键词： Finite element analysis   Insulated gate bipolar transistors   Predictive models   Market research   Temperature measurement   Computational modeling   Temperature distribution   Thermal resistance   Semiconductor device measurement   Mathematical models   Dynamic mode decomposition (DMD)   finite element method (FEM)   insulate-gate bipolar transistor (IGBT)   temperature field prediction  

摘要： The detailed temperature field distribution of high-power insulated gate bipolar transistor (IGBT) modules is important information for the reliability analysis and thermal design of power electronic systems and it is difficult to obtain quickly. This article proposes a hybrid model for temperature field prediction based on dynamic mode decomposition (DMD) and deep learning for IGBT modules. First, the IGBT temperature field (ITF) snapshot is obtained through finite element simulation. Second, the DMD is used to extract stable and unstable trends of the ITF snapshot, and the future stable trend is predicted by recursion. Third, a deep learning model autoencoder-long short-term memory is proposed to predict the future unstable trend. Finally, the ITF prediction snapshots are obtained by adding the future stable and unstable trends. The proposed hybrid model prediction method realizes precise ITF prediction and significantly reduces the computation time. Experimental and simulation results validate the viability of the proposed method.

关键词： Insulated gate bipolar transistors   Stress   Junctions   Failure analysis   Employee welfare   Copper   Temperature distribution   Analytical models   Strain   Molybdenum   Failure weak point   long-term aging failure mechanism   modular multilevel converter (MMC) working condition   press-pack insulated gate bipolar transistor (PP IGBT)  

摘要： Converter valves based on the modular multilevel converter (MMC) topology are the core of the voltage source converter-based high-voltage direct current transmission system, with press-pack insulated gate bipolar transistor (PP IGBT) modules being the key components. Studying the long-term aging failure mechanism of the PP IGBT under actual MMC operating conditions is of great significance for improving the safe and reliable operation of the transmission system. In this article, an electric-thermal-mechanical coupled multifield model of the PP IGBT device is built to analyze the influence of junction temperature and pressure on stress and strain distribution, identifying the weak points. Then, based on the alternating current (ac) power cycling tested rig, which equivalently reproduces the working conditions of the MMC submodule, the influence of different junction temperatures and pressures on long-term aging failure is studied, revealing the evolution of key characteristic parameters during the aging process. Two main failure modes are identified under ac power cycling tests. One mode is caused by overvoltage short-circuit failure due to the blocking voltage drop, and the other is induced by open-circuit failure due to uncontrolled gate current. Finally, the evolution of microscopic morphology and static characteristic parameters over the entire lifetime during the power cycling test are obtained, emphasizing the differences between ac and direct current (dc) power cycling tests. The results show that there are significant differences in overheating failures between ac and dc power cycling tests, highlighting the critical role of ac conditions in failure analysis and reliability assessment. The study of the long-term failure evolution mechanism of the PP IGBT device under actual MMC working conditions aims to guide operational management, control protection, and device optimization design for the reliability of MMC systems.