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关键词： 变频器   谐波电流   永磁同步电机   气隙磁场   高频径向电磁力  

摘要： 采用场路耦合法对永磁同步电机高频径向电磁力特征频率产生原因和主要组成成分进行研究。通过解析法分析谐波电流的产生机理及谐波特性,并利用数值仿真对其进行验证;结合磁动势−磁导法和麦克斯韦张量法分析出高频径向电磁力特征频率的分布;对有限元计算得到的气隙磁场进行时空分解,采用麦克斯韦张量法计算磁场相互作用产生的高频径向电磁力。结果表明,变频驱动下永磁同步电机的高频径向电磁力主要是由变频器谐波电流引入的谐波磁场和定子基波磁场的相互作用产生,这对永磁同步电机的研究提供了一定的指导意义。

关键词： 新能源   DC-DC变流器   电解制氢   状态反馈   线性二次型最优控制   抗扰特性  

摘要： 针对由可再生能源组成的直流电网电解氢系统,通过设计一种基于线性二次型最优控制(LQR)的全状态反馈控制方法,建立全状态误差量的小信号模型,利用系统状态误差量反馈的方法,在新能源并网带来的供电干扰和负荷波动下,改善DC-DC变流器的动态特性,提高电解设备的运行效率和槽内材料的寿命。结果证明,该方法可以显著地降低系统的电压、电流波动时间,且与常规的PI控制相比,对系统干扰的抑制效果更好。最后,对线性二次型最优控制所提出的理论与方法进行仿真验证,证明其正确性与适用性。

关键词： LED照明   功率因数校正   双向无桥反激电路   有源箝位   应力  

摘要： 面向光伏发电等新能源发电和电网供电等多能源联合供电的发光二极管(LED)照明应用场合,为进一步减小电路器件应力和开关损耗,提出一种有源箝位抑制漏感电压尖峰缓冲的多端口双向LED照明驱动电路,实现网侧供电与光伏发电等多能源供电以适应多种照明场景。详细分析所提电路的工作原理和工作过程,以及所提电路在各种工作模式下的稳态工作特性,设计电路关键参数和进行计算机仿真分析,研制1台交流电网输入电压范围为AC 185~265 V、输出电流为2 A、输出功率为96 W的电路实验样机。所提电路在交流电网供电工作模式下,功率因数可达0.998,总谐波失真最小为4.7%,电源效率满载时最高达87.2%。计算机仿真结果与实验结果验证了所提电路有源箝位方法的有效性。

关键词： High-speed train   Insulated Gate Bipolar Transistor (IGBT)   Liquid-cooling plate   Sensitivity analysis   Reasonable matching  

摘要： High-power insulated gate bipolar transistors (IGBTs) are important components of traction inverter. It is important to ensure the suitable temperature of the IGBT module for keeping the operation of trains efficient and safe. Due to the significant differences in train operating environment and traction performance, the cooling requirements for IGBT are also different. Therefore, identifying and matching various parameters of operating parameters of flow and heat transfer in high-power-density IGBT module liquid-cooling plate is of great significance to achieve optimal energy efficiency. Based on the Reynolds-averaged Navier-Stokes equations, shear stress transport k-omega turbulence model, and orthogonal experimental design, the flow and heat transfer characteristics of the liquid-cooling plate were simulated, and the numerical method and settings were verified experimentally. The results show that the single-parameter mapping relationship between the operating parameters and cooling performance indices (pressure drop, temperature rise, and maximum surface temperature, corresponding to Delta p, Delta T, and T-max, respectively) of the liquid-cooling plate is clear, and the flow rate and physical properties of the cooling liquid have significant effects on the cooling performance. The multi-objective optimization method based on the radial basis function surrogate model and nondominated sorting genetic algorithm II can match operating parameters under the minimum of Delta p, T-max and maximum of Delta T. Considering the appropriate values of the three indexes comprehensively based on Pareto optimal solution set, the error between the calculated value and the predicted value is less than 8 % when the inlet flow rate is 20 L/min, the temperature is 330.68 K, the pressure is 2.2 bar and the calorific value is 75.2 kW/m(2). The results can be to provide a method and database for engineers to design liquid-cooling plate for high-speed train IGBT to achieve the highest e

关键词： Insulated gate bipolar transistors   Current density   Magnetic fields   Circuit faults   Magnetic field measurement   Inspection   Magnetic resonance imaging   Circuit health prognostics   current density imaging   insulated gate bipolar transistor (IGBT) modules   nondestructive testing  

摘要： Insulated gate bipolar transistor (IGBT) modules are extensively used in power electronic devices,renewable energy systems, and electric vehicles as keycomponents because of their superiorities of high inputimpedance, high-speed switching, and low saturation volt-age;however, they are usually subject to fault hazards of short-circuit (SC), over voltage, over current and over temperature. Traditional current-voltage inspection methods are limited by their mono-function of indicating fault status,but are incapable of evaluating fault reasons, position, and level. Here, we developed a novel vectorial current density visual inspection method based on the measurement ofthe magnetic field gradient generated by a current-carryingIGBT module. Experiments are conducted by scanning the triaxial fluxgate sensor over the IGBT module in thestandard operation condition. Vectorial features of diver-gence and curl images of vectorial current density are first studied. Typical fault inspection images with obvi-ous characteristic differences are demonstrated based onan experimentally calibrated finite element analysis (FEA)model. A current density resolution of 8.459 A/m(2) is achieved at a probe-to-sample separation of 22 mm, over a maximum scanning area of 400 x 400 mm. Such a method is verified to be capable of imaging spatial vectorial current density, which may offer a novel visualizing technique for in situ inspection for next-generation power semiconductor devices and enable the potential of online health prognostics of power systems

关键词： Insulated gate bipolar transistors   Temperature measurement   Temperature sensors   Traction motors   Inverters   Stator windings   Semiconductor device measurement   Current injection   electric vehicles (EVs)   insulated-gate bipolar transistors (IGBTs)   multi-degree of freedom (multi-DoF) regression   temperature monitoring   traction motors  

摘要： Monitoring the critical temperature of stator windings and power semiconductors is crucial for the thermal safety of electric vehicles (EVs). Embedding temperature sensors is the most common monitoring method used in industry yet is constrained by their lifetime. Temperature-sensitive electrical parameter (TSEP) detection is a promising characterization approach to condition monitoring for a single target. However, due to parameter coupling, there is still a lack of cost-effective thermal monitoring strategies with a homogenous approach for multicomponents. Also, TSEPs are limited by measurement accuracy, not-yet-decoupled resistances, and coupled voltage drop of power semiconductors. To solve these issues, a co-estimation method for the multidimensional temperature of insulated-gate bipolar transistors (IGBTs), their freewheeling diodes (FWDs), and stator windings are proposed. The combinations of TSEPs in the drive circuit are extracted by injecting the sequential current pulses. Then, the proposed multi-degree of freedom (multi-DoF) regression introduces the boundaries to decouple the TSEPs of IGBT and FWD and recurse the corresponding temperatures. Finally, substitute them into the identification algorithm for estimating winding temperature. The experimental results via a prototype permanent magnet synchronous motor (PMSM) test bench are given, and the absolute errors (AEs) of the three targets all remain below 9 degrees C.

关键词： VLF communication   ESA   coupling inductor   IGBT   variable capacitor   impedance optimization  

摘要： The very low frequency (VLF) communication system is characterized by a limited transmit bandwidth. Due to the low operating frequency, the dimensions of VLF antennas are significantly smaller than the corresponding wavelength. Therefore, VLF antennas are considered electrically small antennas (ESAs) with high Q values and narrow bandwidth. To achieve broadband VLF communication, synchronous tuning technology is commonly employed. In this study, we focus on analyzing the performance of the switching device in the synchronous tuning system using coupled inductors and IGBT as core components. By considering the equivalent circuit of the controlled source associated with coupled inductors, we propose an adaptive input impedance optimization algorithm based on the variable capacitor (hereinafter referred to as VC-ADIO) to address issues arising from coupling coefficient variations and internal parameters within IGBTs that affect primary loop input impedance. The radiated power of the VLF antenna is improved effectively.

关键词： Data fusion   Kalman filter   IGBT   Nonstationary signal   Recurrence plots   Recurrence quantification analysis  

摘要： Degradation is a nonstationary process that necessitates using a specialized measurement tool. In light of this, a degradation assessment tool has been presented in this study through the use of recurrence analysis. A fused signal has been constructed through the linear Kalman Filter Fusion Application (KFFA) to assess the growing degradation within the system. This approach aims to combine the features provided by different mediums of the system. A case study is presented using the collector-emitter current and package temperature signals collected during an IGBT 's accelerated aging experiment. Time-frequency and recurrence analyses of fused and collected signals are evaluated to interpret the degradation through the nonstationary characteristics of the signals. The study has two main purposes: to investigate the combination capability of KFFA deeply for nonstationary processes and to define recurrence analysis as a degradation assessment tool. The study explores the relationship between degradation mechanisms and chaotic tendencies. Employing recurrence analysis successfully captures the decay moment of the degradation process. The study is distinctive in its investigation of the recurrence characteristics of a fused signal, which is the mixed representation of multiple sensor data. Additionally, the study demonstrated that the linear KFFA is highly effective in providing integrated and more reliable information even for nonstationary signals. With these contributions, the paper proposes a novel degradation assessment tool driven by recurrence analysis and supported by KFFA.

关键词： Conversion unit   DC-AC converter   IGBT   Temperature  

摘要： This research article discusses the impact of climatic changes in South America, with a case study in a tropical zone, particularly the rise in temperature by 1.15 degrees C from 1998 to 2022, reaching a maximum of 45.85 degrees C in 2023. Focusing on the Electronic Conversion Unit, especially IGBT efficiency during El Nino-Southern Oscillation phenomenon in 2023. The case study employs finite element analysis using Navier Stockes-Boussinesq equations, it evaluates the heat dissipation, airflow modeling, and temperature effects, the research proposes enhancements like redesigned air flow grids, centralized air filters, and wind fans. Implementing these improvements reduces the temperature by 5.6 degrees C, enhances airflow speed, and mitigates the climatic impact on electronic devices over the next two decades.

关键词： Thermal performance   Energy conservation   Field synergy   Entropy generation  

摘要： A thermal-and-energy-conservation optimization was numerically investigated in this work for a liquid-cooled plate (LCP). Firstly, a three-dimensional model was established, and its numerical analysis was verified with experimental data. Then, the common correlations of heat transfer synergy beta and pressure synergy theta involving the amplification factor, the width of cooling columns, the number of cooling columns, the height and the width of flow passage were derived from the traditional Colburn factor j and Fanning friction factor f correlations, which were later solved by the least-square method and tested with regression and joint hypotheses test. With those correlations, a multi -objective optimization was performed, and its outcomes were assessed by a comprehensive evaluation index Comprehensive synergy gamma for thermal performance and auxiliary entropy generation for energy conservation. At last, Optimized Scheme 2 (OS2) was numerically compared with the original one to confirm improvements. It is found that, over the whole speed range, the maximum error between both results is 6.61 %. The test shows that the fitting correlation may predict 94.79 % of beta with a -0.039 % mean error and 98.96 % of theta with a 0.099 % mean error. Among outcomes, OS2 contributes a better gamma, 51.3465 degrees, for thermal performance and a smaller entropy generation, 0.09175 W/K, for energy conservation. Furthermore, the comparison also supports that finding with the decreased beta of 0.39 %, the decreased theta of 3.33 %, the increased gamma of 0.34 %, and the increased entropy generation of 3.99 % in OS2. The research results can provide a basis for the design and development of a high -power loader.