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关键词： amplifier   gallium oxide   microwave frequencies   split recessed gate   TCAD simulations   wide bandgap semiconductors  

摘要： In this study, a split-recessed-gate Ga2O3 MOSFET has been proposed for high-frequency applications. Extensive simulations have been carried out using TCAD Silvaco to examine the analog characteristics as well as the critical high-frequency metrics of the proposed device. A comparison has been drawn with conventional recessed-gate beta-Ga2O3 MOSFET, and it is demonstrated that the proposed device outperforms the conventional device in terms of the high-frequency metrics due to its significantly lower parasitic capacitances and higher intrinsic gain. In addition, it was also demonstrated that the proposed device exhibits a substantial increase of 127.7% in the Johnson's figure of merit, significantly higher, i.e. 134.7% higher, than Baliga's high-frequency figure of merit, as well as a 3.25% increase in Baliga's figure of merit as compared to the conventional device. Furthermore, a two-port network analysis has been carried out for both the devices and it has been shown that the proposed device offers higher gain with a slight trade-off in the reflections at the input/output ports. The scattering parameters have also been extracted and used to perform the stability analysis. It was observed that the proposed device exhibits higher stability for the entire frequency range. Furthermore, a maximum gain amplifier was designed using the proposed device. An impressive gain of 11.04 dB was demonstrated at an ultra-high frequency of 3 GHz.

关键词： 三电平双有源桥DC-DC变换器   零电压开通   回流功率   双重移相   变压比  

摘要： 针对中点箝位三电平双有源桥DC-DC变换器存在回流功率及开关管损耗问题，提出一种零电压开通边界和范围内减小回流功率的优化控制策略。该控制策略在实现全部开关管零电压开通的前提下，减小回流功率。在双重移相控制下，分析三电平DAB变换器的工作原理，得到零电压开通范围，并且建立传输功率和回流功率的数学模型，分别在零电压开通边界和范围内对回流功率进行优化，最后通过仿真和实验平台验证了控制策略的有效性。

关键词： 大功率器件   准在线测试   应用特性   可靠性分析  

摘要： 高压大功率器件目前己广泛应用于各类大容量电力换流和控制装备中,在运行过程中面临复杂的电-磁-热-机应力,具有功率密度大、工况态势复杂的特点,开展高压大功率器件的特性测试有利于准确评估功率器件的可靠性,并指导变流器的优化设计.该文紧密围绕基于双脉冲的准在线测试方法,系统综述准在线测试在结温提取、老化表征、运行轨迹刻画、电磁云图分布等方面的应用情况和发展现状,梳理不同特性表征方法的优缺点及适用性,并进一步探讨在线运行工况下功率器件的实时状态监测和寿命评估方法.同时,面向第三代碳化硅半导体器件,深入讨论基于宽禁带材料电致发光原理的测评新方法,为后续高压大功率器件的可靠性评估提供指导和参考.

关键词： 输出功率   超宽带功率放大器   功率合成   Wilkinson功分器   多层混压板  

摘要： 针对信号发生器输出功率越来越高，而超宽带功率放大器输出功率和工作效率比较低的问题，本文提出一种平面微带功率合成技术。该技术主要采用超宽带Wilkinson功分器实现功率分配及合成。据此，本文采用多层混压板设计出一款超宽带功率合成电路：工作频率为6～20GHz，饱和输出功率大于32.5dBm，全频段合成效率大于70%。经实测验证：平面微带功率合成技术既可以提高输出功率，又可以将两个放大器分开，有效增大散热面积，保证电路的可靠性。

关键词： 相互作用分析   同步环   功率平衡   带宽   线性化模型  

摘要： 由于跟网型变流器系统由控制主导、强耦合的特性，锁相同步与直流电容上功率平衡的关系并不清晰。为此，从带宽视角揭示了两者在带宽远离、接近时的交互机制。首先基于两者的动力学行为，以阻尼比和振荡频率作为前者的动态指标，以同步转矩和阻尼转矩作为后者的动态指标。之后利用奇异摄动理论将所建线性化模型在临界场景下进行代数化降维，通过分析动态指标的变化揭示了两者在带宽远离时的相互作用。其次基于功率平衡开环传递函数，分析锁相同步对功率平衡环节幅值裕度的影响，揭示了两者带宽接近时的相互作用。特别地，本文考虑了端电压控制的影响，发现其带宽降低会恶化两者间的相互作用，导致系统静态稳定极限减小，带宽接近易失稳的现象消失。

关键词： 高频变压器   损耗统计理论   Energetic模型   磁导-电容类比法   频率效应  

摘要： 高频变压器是能量路由器、光伏逆变器等功率变换装置的关键设备，面临复杂的运行环境与电磁暂态工况。为了构建精确的高频变压器电磁暂态模型，需要准确模拟铁芯动态磁滞特性。本文首先在电力电子仿真软件PLECS中将磁导-电容类比法与Energetic磁滞模型相结合，构建表征静态磁滞效应的铁芯静态磁滞磁导模型；其次，在静态磁滞磁导模型基础上，依据损耗统计理论，引入磁阻和受控磁动势源用以表征铁芯涡流损耗和剩余损耗的动态损耗分量，构建出铁芯动态磁滞磁导模型；然后，基于不同工况下实验测量数据，结合损耗统计理论与场分离技术获得各频率下静态磁滞回线，推导静态模型参数随频率变化规律，得到考虑静态参数频率效应的动态磁滞磁导模型特征参数；最后，将所建铁芯模型在不同频率、不同磁密的正弦波与不同占空比方波激励下的仿真结果与实验测量结果进行对比分析，验证了本文所建铁芯模型的有效性。

关键词： 铝合金   振镜扫描激光-双脉冲CMT复合   温度场   等离子体  

摘要： 为了探究螺旋型扫描激光功率对铝合金双脉冲冷金属过渡(cold metal transfer, CMT)增材电弧热场、熔滴过渡行为及气孔缺陷的影响规律，设计变功率激光电弧复合增材制造对比试验，并利用红外热成像、光谱测量和高速摄像技术研究分析引入扫描激光后近熔池表面电弧径向温度场分布、复合交叉区等离子体行为以及对熔滴过渡和气孔缺陷的影响.结果表明，双脉冲CMT近熔池表面电弧径向温度场变化剧烈，温度梯度大，电弧稳定性较低.当引入600～1 200 W扫描激光时，电弧径向温度分布趋于均匀化，温度梯度明显减小，近熔池表面电弧温度显著提高(最高温度可提高约900℃)，促使Mg,Al原子电离产生更多数量的MgⅡ、MgⅢ、AlⅡ及AlⅢ离子，提高电弧稳定性；当激光功率为600 W和1 200 W时，电子密度分别增加6%和17%，电子温度分别提高400 K和800 K.激光金属蒸汽有效降低熔滴过渡频率，减弱熔滴对熔池的冲击作用，使熔池趋于稳定；同时，增材件气孔数量明显减少、分布趋于分散化，当激光功率为1 200 W时，气孔几乎消失殆尽.创新点：(1)提出了功率调制振镜扫描激光与双脉冲CMT电弧复合增材制造新方法.(2)揭示了螺旋扫描激光功率调控CMT电弧热场的物理本质.

关键词： Voltage   Inductors   Capacitors   Topology   MOSFET   Voltage measurement   Transient response   Buck-boost   dc-dc converter   fast transient response   flying capacitor   hybrid converter   lithium-ion (Li-ion) battery   no right-half-plane zero   switched capacitor   three-fine-level buck-boost (3FLBB)  

摘要： This article presents a non-inverting three-fine-level buck-boost (3FLBB) hybrid converter suitable for lithium-ion (Li-ion) batteries. With seven power switches and two flying capacitors, the proposed 3FLBB converter produces the voltage of switching node between V-IN/2, V-IN , and 3 V-IN /2, which supports buck, boost, and buck-boost modes, and with smooth mode changes. Here, one of the two flying capacitors is used to drive the inductor (L), while another one is used to ensure that V-DS of each power switch is within 1/2V(IN) in all phases. Hence, the voltage stress of all the power switches is reduced to half-V-IN, and the normalized equivalent resistance and switching losses are greatly reduced by using two 1.8-V switches instead of two 5-V switches. Since the three modes all have buck-like operation, the average inductor current is reduced to always equal to the output current. Meanwhile, they all have continuous output current, similar complex pole pairs, and no right half-plane (RHP) zero, which enables fast load transient response. This design is implemented by only 1.8-V devices of a standard 0.18-mu m CMOS process, covering an input voltage range from 2.8 to 4.2 V. A 98.2% peak efficiency is measured at 2-MHz switching frequency with 2.2-mu H L, two 10-mu F mu F flying capacitors, and one 10-mu F output capacitor. It can deliver an output current of 50-1000 mA at a 3.3-V regulated output voltage. Moreover, the measured results show that this design achieves a significant improvement on undershoot and overshoot voltage than the previous works.

关键词： 变压器故障   电气试验技术   应用  

摘要： 本文从变压器的基本概况出发,详细探究了变压器的组成与类型,指出变压器在运行期间的常见故障,并阐述了变压器故障分析中几种常见的电气试验技术,以及每种电气试验技术的操作原理及注意事项,强调了电气试验对判定和分析变压器故障的重要作用.

关键词： SiON   NBTI   Reliability   Performance   MOSFET   Ring oscillator  

摘要： The impact of different SiON manufacturing processes on performance and reliability behaviors has been investigated for the MOSFETs. The performance of devices composed of an ultrathin SiON film fabricated by the novel low-temperature and low-pressure mild oxidation after the plasma solidification (LLMOPS) method can be enhanced compared to conventional processes, which is attributed to the increased mobility. It is observed from secondary ion mass spectrometry analysis that the distribution of nitrogen with the LLMOPS process moves toward the upper surface of SiON. As a result, the p-MOSFET manufactured by the LLMOPS process exhibits lower electrical performance degradation during the NBTI stress, indicating that a reduction in nitrogen concentration at the Si/SiO2 interface contributes to improving NBTI behavior. It is also demonstrated that the inhibition of NBTI phenomena enhances the frequency stability on the ring oscillator with circuit simulation. Thus, the LLMOPS process is a promising approach to improve the performance and reliability of MOSFETs in mass production.