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关键词： 随机游动   等级差异   初始分布   最优控制   法锥   变分原理  

摘要： 研讨一类基于年龄等级结构和空间扩散行为的种群系统模型的最优控制问题,其状态系统由二阶非线性偏微分积分方程描述,控制变量为种群初始分布,指标泛函表征任意固定时间段后的种群资源净收益.运用法锥理论并构造恰当的共轭系统方程建立了最大值原理,扩充指标泛函且应用Ekeland变分原理及不动点方法证明了最优解的存在唯一性.数值实验显示了所得理论成果的可应用性.

关键词： IGBT   MOSFET   MPWM   Switching loss   Temperature  

摘要： Despite the fact that temperature affects how much power is produced by solar panels, a temperature that exceeds a certain threshold results in a reduction in output. Additionally, there are losses when switching is controlled in inverters using different control approaches like pulse width modulation (PWM), sinusoidal pulse width modulation (SPWM), and multiple pulse width modulation (MPWM). The type of control method and temperature have an impact on these losses. Here, the MPWM approach is used to analyze it at various temperatures. A metal-oxide-semiconductor field-effect transistor or MOSFET-based and an insulated gate bipolar transistor (IGBT)-based inverter are also planned. Their switching losses at various temperatures are contrasted. For a range of temperature values, the IGBT-equipped inverter is discovered to be a low-loss inverter. Compared to an IGBT inverter, the MOSFET inverter has a comparatively higher loss. © 2024, Institute of Advanced Engineering and Science. All rights reserved.

关键词： 开关磁阻电机   直接转矩控制   模型预测控制   转矩脉动  

摘要： 针对开关磁阻电机采用传统直接转矩控制易产生较大的转矩脉动问题,提出一种九扇区模型预测控制方法。首先,建立含有永磁辅助式开关磁阻电机的新型指数型磁链模型,以预测下一时刻的磁链和转矩值;其次,根据电感特性将转子周期划分为九个扇区,并重新分配各扇区对应的候选电压状态,降低系统在每个采样周期的计算量;通过设计的目标函数,在线得到一个最优控制序列。仿真验证结果表明:与传统DTC方法相比,在转速分别为500、1000和1200 r/min以及负载分别为5和10 N·m工况下,转矩脉动系数分别降低了4.8%、43.4%、61.4%和9%、32.53%、47.4%,对抑制电机的转矩脉动有着更好的效果。

关键词： IGBT   寿命分散性   串联   功率循环试验   老化   表征方法  

摘要： IGBT器件采用串联拓扑增加耐压等级以满足实际应用需求,但多器件串联增加了老化参数的监测数量和难度。为了研究寿命分散性对器件串联寿命的影响,揭示不同失效模式下串联IGBT与单一IGBT的寿命差异,首先,分析了功率循环中现有的老化参数监测方法,提出了寿命的特征分析模型;然后,结合失效分离的试验方法,分析了功率循环中键合线失效和焊料老化两种典型失效形式下的寿命分散性对串联寿命评估的影响;最后,分析了寿命高分散性和串联数量对器件串联寿命的影响,建立了寿命分散性差异与器件串联的老化表征方法有效性的关系,提出了考虑寿命分散性的器件串联老化监测的监测单元最大数量,为减少器件串联数量提供了实验和理论依据。

关键词： Ca^(2+)   β淀粉样蛋白   双稳态   抑制剂   最优控制  

摘要： 阿尔茨海默病的主要病理特征是脑内β淀粉样蛋白斑块沉积及Ca^(2+)稳态失衡。为此,不同的抑制剂被研发出来用于抑制β淀粉样蛋白和Ca^(2+)的浓度,以期减缓阿尔茨海默病的疾病进程。本文基于Ca^(2+)与β淀粉样蛋白之间的相互作用,构建并分析了一个考虑抑制剂作用的最优控制模型。首先,从理论层面给出了系统出现双稳现象的阈值条件;其次,利用Pontryagin极小值原理求得最优控制策略;最后,基于数值模拟结果探究不同控制策略的作用效果。研究结果表明相比较于单一类型抑制剂的使用,β淀粉样蛋白抑制剂和Ca^(2+)抑制剂的联合作用能够有效地降低β淀粉样蛋白水平,进而控制疾病进程。

关键词： 绝缘栅双极晶体管   结温在线监测   热敏感电参数   导通压降   双脉冲测试   三维映射表征模型   采样电路  

摘要： 热敏感电参数法具有在线能力强、非侵入和快响应等特点,成为了当前的研究热点。因此以导通压降为热敏感电参数,重点研究了1种基于导通压降的IGBT结温在线监测方法。首先,通过双脉冲测试电路获取IGBT导通压降、集电极电流和结温数据;然后,基于所测数据构建了IGBT集电极电流、结温与导通压降的三维映射表征模型;最后,设计了1种新型导通压降采样电路,并开展IGBT结温的在线监测实验研究,实验结果验证了所得三维结温表征模型的准确性和有效性。

关键词： Insulated gate bipolar transistors   X-ray imaging   Stress   Temperature measurement   Silicon   Heating systems   Inspection   Die-attach   fast power cycling test (PCT)   fatigue crack network (FCN)   insulated-gate bipolar transistor (IGBT)   Sn-Ag-Cu (SAC) solder  

摘要： The die-attach layer is a vulnerable structure that is important to the reliability of an insulated-gate bipolar transistor (IGBT) module. A new failure mechanism named fatigue crack network (FCN) has been identified in the central area of the IGBT modules' solder layer. In this article, to investigate the formation mechanism of the FCN, a fast power cycling test (PCT) (current on 0.2 s and current off 0.4 s) was designed and performed on a commercial IGBT module. Subsequently, scanning acoustic microscopy and X-ray imaging were used for nondestructive inspection of the defects of the solder layer. The cross section was based on the nondestructive inspection results. Then, electron backscattered diffraction analysis was carried out on both observed vertical and horizontal cracks. As a result, both networked vertical cracks at the center and horizontal cracks at the edge of the solder layer were detected. The recrystallization occurred during the PCT. The voids and cracks emerged at high-angle grain boundaries. A finite element simulation was performed to understand the driving force of FCN qualitatively. The stress simulation results indicate that under time-dependent multiaxial stress at the center of the solder, the defects nucleated, expanded, and connected vertically to form the FCNs.

关键词： Wire   Insulated gate bipolar transistors   Junctions   Aging   Monitoring   Couplings   Transient analysis   Data models   Voltage   Temperature sensors   Bond wire aging monitoring (AM)   bond wire degradation voltage (V-BWD)   insulated gate bipolar transistor (IGBT) modules   on-state voltage evolution model (OSVEM)  

摘要： The issue of the bond wire aging obviously degrades the reliability of insulated gate bipolar transistor (IGBT) modules, and thus, the bond wire aging monitoring (AM) method is highly desired. However, many AM methods are subjected to the effects of junction temperature variations and consequently suffer from degraded accuracy. To address this, a bond wire AM method based on the bond wire degradation voltage ( V-BWD ) is proposed, which can mitigate the effects of junction temperature variations. In the proposed AM method, with the established multiphysics field coupling model of the IGBT module, V-BWD is selected as the bond wire aging indicator, which is not affected by junction temperature variations. Moreover, an extracting method of V-BWD based on the ON-state voltage evolution model (OSVEM) is developed. Afterward, the availability of V-BWD is thoroughly investigated by using the double-pulse tests. Finally, the effectiveness of the proposed bond wire AM method is verified by experimental tests.

关键词： IGBT cooling   Manifold microchannel heat sink   Physics-informed neural network   Numerical simulation  

摘要： This study explores the application of Physics-Informed Neural Networks (PINNs) in modeling fluid flow and heat transfer dynamics within intricate geometric configurations, focusing on manifold microchannel (MMC) heat sinks designed for efficient high-power IGBT cooling. A deep neural network architecture comprising two subPINNs, one for flow dynamics and another for thermal behavior, is developed, each initialized with a sine activation function to capture high-order derivatives and address the vanishing gradient problem. Comparisons between PINN and CFD simulations reveal close agreement, with both methods showing an increase in pressure drop and a decrease in temperatures as inlet velocity increases. Discrepancies arise in scenarios with rapid flow pattern or gradient changes, highlighting PINNs' sensitivity to geometric complexity and numerical stability. Overall, this study underscores PINNs' potential as a promising tool for advancing thermal management strategies across various engineering applications.

关键词： Insulated gate bipolar transistors   Switches   Logic gates   Analytical models   Voltage   Scanning electron microscopy   Robustness   Optimization   Integrated circuit modeling   Capacitance   1200-V insulated-gate bipolar transistor (IGBT)   failure mechanisms   short-circuit safe operating area (SCSOA) optimization   short circuit   TCAD model   Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS)  

摘要： Power electronics are widely used in new energy vehicles, photovoltaics, and other fields. Its robustness has been concerned, and short-circuit robustness is an essential part of it, which is worth in-depth research. In this work, a 1200-V Trench-field-stop (FS) insulated-gate bipolar transistor (IGBT) was focused on for its short-circuit safe operating area (SCSOA) capability analysis. First, a model based on the actual process flow was set up, aligned with the scanning electron microscope (SEM) results, with the discrepancy between its static and dynamic electrical characteristics controlled within 5% and 12%, respectively. Subsequently, two primary failure modes and mechanisms of the device under test (DUT) under short-circuit conditions were identified, analyzed through TCAD modeling, and verified through actual short-circuit tests. Finally, the Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) method for multiple-criteria decision-making (MCDM) was applied to optimize the SCSOA, enhancing the short-circuit robustness of the device by 4% with minimal loss to other electrical performances.