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关键词： IGBT   反向电动势   滤波   安全性  

摘要： 为了解决IGBT在关断过程中由于负载回路存在感性,IGBT集电极或发射极产生反向电动势导致IGBT被过压击穿的问题,本文提出使用RDC滤波电路进行电压尖峰有效滤除的设计理念。通过两路滤波电路对电压尖峰进行吸收并且不会影响IGBT原有的接通关断时间,可有效地保护IGBT不会在反向电动势所产生的电压尖峰下击穿。同时本设计也可以应用于其他功率器件的接通关断滤波电路中,提高了功率器件的安全性。

关键词： Boost变换器   SiC模块   IGBT模块   热损耗  

摘要： 针对Boost变换器中SiC(碳化硅)与IGBT模块热损耗问题,给出了Boost电路中功率模块热损耗的估算方法,并提供了具体的估算公式。以30 kW DC/DC变换器为研究对象,对功率模块在不同工作频率下的损耗进行了理论计算、PLECS仿真和试验验证对比分析。PLECS仿真和试验验证的结果不仅证明了估算公式的正确性,还直观的体现了SiC和IGBT两类模块在不同开关频率下工作的热损耗趋势。从文中可以看出,使用SiC替代IGBT可以显著地提高变换器的工作频率和功率密度。

关键词： 欧式行车   变频器   调试检修  

摘要： 文章着重研究欧式行车用变频器参数优化调整及故障检修。以一种变频器为例,结合欧式行车的具体特点,阐述了变频器在欧式行车应用中参数优化调整及针对运行中出现的故障维修提出处理方案。

关键词： Logic gates   Insulated gate bipolar transistors   Voltage measurement   Plasmas   Current measurement   Plasma measurements   Inductance   Insulated gate bipolar transistor (IGBT)   plasma   short-circuit   TCAD-simulation  

摘要： The second type of short-circuit (SC II) of an insulated gate bipolar transistor (IGBT) considering the plasma is thoroughly studied in this article. The measurement and device simulation were performed for 1.2 kV IGBTs. Since the SC II is the failure during the IGBT conduction mode, the existing plasma within the IGBT plays an important role in IGBT SC II behavior. The first focus of this article is to understand the composition of the current peak at the beginning of the SC II, which is produced by the Miller-effect during the desaturation process and the sweep-out of the internal plasma. Further, the induced voltage caused by the current decay after the current peak is investigated. The interaction between current decay and the IGBT internal physical mechanism is discussed under different test conditions.

关键词： Mathematical models   Computational modeling   Couplings   Estimation   Atmospheric modeling   Partitioning algorithms   Thermal conductivity   Compact thermal model   coupled system   interface   loosely coupled algorithm   partition decoupling  

摘要： This letter proposes a partition decoupling algorithm for the compact thermal model to reduce the computation burden in the multichip insulated gate bipolar transistor modules. As a typical coupled system, the compact thermal model is split into separate thermal models with several shared interfaces. The interface data, coupling power loss, coming from the previous time step is used to calculate the real temperature in the current time step. The proposed algorithm transforms the spatial coupling of the compact thermal model into the temporal coupling. Furthermore, based on the proposed partition decoupling algorithm, some more loosely coupled algorithms are also designed. Finally, both simulation and experiment are conducted to verify three loosely coupled algorithms.

关键词： Current measurement   IGBT   measurement error   multiple chips   printed-circuit board Rogowski coil (PCB RC)  

摘要： Unbalance of transient currents of multiple chips inside press-pack insulated-gate bipolar transistor (PP IGBT) results in degrading operation and even device damage. Chip currents measurement plays an essential role to understand and solve this problem. Printed-circuit board Rogowski coil (PCB RC), as a small, noninvasive, and high bandwidth current sensor, is very suitable for this application. However, PCB RC integrated with multiple Rogowski coils (RCs) is still difficult to be applied to measure the current of multiple chips in press pack IGBT device because of the low measurement accuracy due to the large interference. In this letter, a high accuracy PCB RC with ten rectangular RCs inside PP IGBT is proposed to measure ten chip currents at the same time. Different from single RC measuring single chip current, the interference of adjacent chip currents has to be considered, and is reduced to 0.6% by optimizing the turns arrangement and lead wires of RCs. The noise of cross talk of adjacent RCs is 1.7% by decreasing the capacitance coupling between RCs. Shielding layers and grounding patter of lead wires for ten RCs are proposed to eliminate the interference of collector voltage. The experiment of transient process of ten chips verifies the effectiveness of proposed PCB RC, and measurement error is only 1.8%.

关键词： IGBT   Circular thermal diffusion boundary   Cauer model   Parameter extraction  

摘要： Considering the change of working conditions, the calculation of thermal resistance and thermal capacity with the fixed shape of heat conduction area will result in a large calculation error for junction temperature of the Cauer model. Based on the conventional Cauer model, a circular heat conduction area is chosen to calculate the thermal resistance and thermal capacity in this manuscript, which avoids the inaccurate calculation of heat conduction area under different working conditions by the fixed heat diffusion angle method. In addition, a few fiber grating sensors are arranged on the baseplate to track the selected isotherm in real time, and update the isotherm as the thermal diffusion boundary according to the simulation rule. Furthermore, accurate thermal resistance and thermal capacity values are calculated online according to the circular heat conduction area that its boundary is the selected isotherm. Finally, the correction of the Cauer model with real-time updated thermal resistance and thermal capacity can calculate a more accurate junction temperature.

关键词： Average temperature   Insulated gate bipolar transistor   IGBT   Maximum temperature   Temperature distribution   Temperature uniformity  

摘要： Following improvements in their operating voltage levels, insulated gate bipolar transistors (IGBTs) are largely packaged using parallel packaging processes. However, these processes introduce an uneven temperature dis-tribution problem, regardless of whether pressed or welded packaging is used. In this paper, the temperature inhomogeneity of IGBT modules under various test conditions is studied using a thermography camera. The temperature uniformity is determined for each chip using the difference between its maximum and average temperatures. IGBT module temperature uniformity is evaluated using the difference between the highest temperature and the average temperature of three chips. Experimental results show that when the current level increases, the overall IGBT module temperature also increases. The temperatures of both the module and the chip become increasingly uneven. The temperature of the module shows a Gaussian mode distribution. The positional and discrete parameters of the Gaussian distribution increase with increasing current. As the ambient temper-ature increases, the temperature inhomogeneity in each IGBT chip increases, but this trend is not dramatic. When the current on-time increases, the temperature distributions of the three IGBT chips and the module gradually become nonuniform.

关键词： 反问题   抛物型方程   时间分数阶扩散方程   最优控制   Tikhonov正则化  

摘要： 反问题在航空航天、医学成像、生物传热等多个领域具有重要应用.在经典意义下其往往是不适定的,这也成为我们研究的难点之一.本文主要研究在生物传热背景下的两类系数反演问题,我们将利用不同的附加条件同时反演与空间相关的灌注系数和初始温度.当前,热疗技术迅速发展,血液灌注率对生物组织内温度分布有重要影响.此外,在许多相关应用中,扩散过程的初始温度也是未知的.因此,在这个框架下,我们讨论二维线性二阶抛物型方程和时间分数阶扩散方程的系数重构问题,该问题的现实意义不言而喻.本论文的主要内容如下:第一章主要介绍了反问题的基本情况,以及基于生物传热背景的研究现状,最后介绍了本文的主要工作.第二章主要在生物传热背景下,研究了一类利用附加条件重构二维线性二阶抛物型方程灌注系数和初始温度的反问题.与其他文献不同,本章研究的是非局部和对流边界条件,更为困难和复杂.基于最优控制理论,构造了包含两个独立变量和两个独立正则化参数的二元泛函,将原问题转化为一个优化问题,讨论了最优解的存在性和所满足的必要条件.由于控制泛函是非凸的,不存在全局唯一解,此时假设终端时间T相对较小,可以成功推导出极小元的唯一性和稳定性.第三章主要研究了一类利用附加条件重构时间分数阶扩散方程中灌注系数和初始温度的反问题.此时附加条件并非通常意义下的终端观测值,而是两个带有线性无关的权重函数的积分型观测数据.首先我们证明了一类弱形式的正问题解的存在唯一性.其次由于反问题是不适定的,利用Tikhonov正则化方法将原问题转化为变分问题,再利用观测数据及先验估计,构造了相应的极小化严格凸泛函,给出了变分问题正则解的存在性、稳定性和收敛性.第四章对本文工作的结论和不足进行了简单总结,并对后续工作做了进一步展望.

关键词： 永磁直线同步电机(PMLSM)   反电势积分法   状态切换   矢量控制   无位置传感器控制   磁链中值法  

摘要： 永磁直线同步电机(Permanent Magnet Linear Synchronous Machine,PMLSM)具有结构简单、高加速度、高效率、高功率因数、高推力密度、高定位精度和可控性好等优点,PMLSM被越来越多地应用于工业加工领域的高速物流线与柔性自动化产线等长行程设备。目前针对无位置传感器控制的长行程垂直运动PMLSM的研究较少,其特点是需要保障带位能性负载的可靠起动,因此本文主要研究垂直运动PMLSM的无位置传感器控制方法。 本文综述了PMLSM和无位置传感器控制的国内外相关文献,阐述了PMLSM数学模型、矢量控制方法和空间电压矢量脉宽调制(SVPWM)技术,在此基础上,主要完成了以下工作: (1)对比分析了现有无位置传感器控制策略的优缺点,根据垂直运动表贴式PMLSM带位能性负载起动的需求,提出了一种采用结合IF控制与反电势积分法的无位置传感器控制策略。 (2)基于Matlab/Simulink搭建了所提出的结合IF控制与反电势积分法的无位置传感器控制系统仿真模型,仿真分析了运行性能及控制参数的影响。首先分析了低速域观测磁链的漂移问题,提出了采用磁链中值抵消漂移的方法;其次分析了开闭环切换时状态切换角对运行性能的影响,得到了适用的状态切换角;然后分析了电阻/电感参数与电压调节速率对运行性能的影响;最后仿真了不同负载时的运行性能,验证了算法的带载能力。 (3)搭建了垂直运行的表贴式PMLSM实验平台,完成了硬件与软件系统的设计,基于该平台进行了算法测试。在频率3Hz时,利用仿真求得的状态切换角,PMLSM开环起动后平稳切换到了闭环,进入闭环后若出现一定范围内的负载突变或参考速度突变也能够快速跟踪,实现了PMLSM的无位置传感器控制。同时,测试了电阻/电感参数与电压调节速率对算法的影响。最后,测试了PMLSM带不同位能性负载时的垂直运行性能,验证了所提出算法的有效性。