Neutron irradiation influence on high-power thyristor device under fusion environment

Because of their economy and applicability,high-power thyristor devices are widely used in the power supply systems for large fusion devices.When high-dose neutrons produced by deuterium–tritium(D–T)fusion reactions are irradiated on a thyristor device for a long time,the electrical characteristics of the device change,which may eventually cause irreversible damage.In this study,with the thyristor switch of the commutation circuit in the quench protection system(QPS)of a fusion device as the study object,the relationship between the internal physical structure and external electrical parameters of the irradiated thyristor is established.Subsequently,a series of targeted thyristor physical simulations and neutron irradiation experiments are conducted to verify the accuracy of the theoretical analysis.In addition,the effect of irradiated thyristor electrical characteristic changes on the entire QPS is studied by accurate simulation,providing valuable guidelines for the maintenance and renovation of the QPS.

Ultra-high voltage 4H-SiC gate turn-off thyristor for low switching time

An ultra-high voltage 4H-silicon carbide(Si C) gate turn-off(GTO) thyristor for low switching time is proposed and analyzed by numerical simulation. It features a double epitaxial p-base in which an extra electrical field is induced to enhance the transportation of the electrons in the thin p-base and reduce recombination. As a result, the turn-on characteristics are improved. What is more, to obtain a low turn-off loss, an alternating p^+/n^+region formed in the backside acts as the anode in the GTO thyristor. Consequently, another path formed by the reverse-biased n^+–p junction accelerates the fast removal of excess electrons during turn-off. This work demonstrates that the turn-on time and turn-off time of the new structure are reduced to 37 ns and 783.1 ns, respectively, under a bus voltage of 8000 V and load current of 100 A/cm^2.

100 kA/10kV thyristor stack design for the quench protection system in CRAFT

Thyristors have longer lifetimes,higher reliability,and very high voltage and current ratings and they require less maintenance than other high-power semiconductor devices.As a result,they are particularly suitable for quench protection systems(QPSs),which protect the superconducting magnets in large fusion devices from damage.In this paper,we propose a design for a 100 k A/10 k V thyristor stack supported by both theoretical and simulation-based analyses as well as experimental verification.Due to the ultrahigh electrical performance requirements imposed on the QPS by the Comprehensive Research Facility for Fusion Technology(CRAFT),three main issues must be considered:the voltage-balancing problem caused by multiple thyristors in a series structure,the increased junction temperature problem caused by extremely high currents,and the reverse recovery phenomenon that arises from the thyristor’s physical structure.Hence,a series of detailed theoretical analyses,simulations,and experiments,including a thyristor junction temperature prediction method and reverse recovery process modeling,were carried out to optimize the design.Finally,the reliability and stability of the thyristor stack were verified by a series of prototype experiments.The results confirmed the correctness and accuracy of the proposed thyristor stack design method and also indicated that the proposed thyristor stack can meet the application conditions of a 100 k A QPS in the CRAFT project.

An integrated split and dummy gates MOSFET with fast turn-off and reverse recovery characteristics

A power MOSFET with integrated split gate and dummy gate(SD-MOS) is proposed and demonstrated by the TCAD SENTAURUS.The split gate is surrounded by the source and shielded by the dummy gate.Consequently,the coupling area between the split gate and the drain electrode is reduced,thus the gate-to-drain charge(Q_(GD)),reverse transfer capacitance(C_(RSS)) and turn-off loss(E_(off)) are significantly decreased.Moreover,the MOS-channel diode is controlled by the dummy gate with ultra-thin gate oxide t_(ox),which can be turned on before the parasitic P-base/N-drift diode at the reverse conduction,then the majority carriers are injected to the N-drift to attenuate the minority injection.Therefore,the reverse recovery charge(Q_(RR)),time(T_(RR)) and peak current(I_(RRM)) are effectively reduced at the reverse freewheeling state.Additionally,the specific on-resistance(R_(on,sp)) and breakdown voltage(BV) are also studied to evaluate the static properties of the proposed SD-MOS.The simulation results show that the Q_(GD) of 6 nC/cm^(2),the C_(RSS) of 1.1 pF/cm^(2) at the V_(DS) of 150 V,the QRR of 1.2 μC/cm^(2) and the R_(on,sp) of 8.4 mΩ·cm^(2) are obtained,thus the figures of merit(FOM) including Q_(GD) ×R_(on,sp) of50 nC·mΩ,E_(off) × R_(on,sp) of 0.59 mJ·mΩ and the Q_(RR) × R_(on,sp) of 10.1 μC·mΩ are achieved for the proposed SD-MOS.

Improvement of circuit oscillation generated by underwater high voltage pulse discharges based on pulse power thyristor

High voltage fracturing technology was widely used in the field of reservoir reconstruction due to its advantages of being clean, pollution-free, and high-efficiency. However, high-frequency circuit oscillation occurs during the underwater high voltage pulse discharge process, which brings security risks to the stability of the pulse fracturing system. In order to solve this problem, an underwater pulse power discharge system was established, the circuit oscillation generation conditions were analyzed and the circuit oscillation suppression method was proposed. Firstly, the system structure was introduced and the charging model of the energy storage capacitor was established by the state space average method. Next, the electrode high-voltage breakdown model was established through COMSOL software, the electrode breakdown process was analyzed according to the electron density distribution image, and the plasma channel impedance was estimated based on the conductivity simulation results. Then the underwater pulse power discharge process and the circuit oscillation generation condition were analyzed, and the circuit oscillation suppression strategy of using the thyristor to replace the gas spark switch was proposed. Finally, laboratory experiments were carried out to verify the precision of the theoretical model and the suppression effect of circuit oscillation. The experimental results show that the voltage variation of the energy storage capacitor, the impedance change of the pulse power discharge process, and the equivalent circuit in each discharge stage were consistent with the theoretical model. The proposed oscillation suppression strategy cannot only prevent the damage caused by circuit oscillation but also reduce the damping oscillation time by77.1%, which can greatly improve the stability of the system. This research has potential application value in the field of underwater pulse power discharge for reservoir reconstruction.

新一代高韧性直流输电技术(一):从器件、装备到系统

构建高比例新能源、高比例电力电子化的新型电力系统迫切需要具有超强构网和主动支撑能力的新型直流输电技术。为此,文中秉承“一代器件、一代装备、一代系统”理念,提出新一代高韧性直流输电概念。增强型集成门极换流晶闸管(enhanced integrated gate-commutated thyristor,IGCT-Plus)的半导体本征结构拥有超强的浪涌电流能力,将为高暂态耐受的换流器提供坚实的物理基础;新型模块化换向式换流器(modular commutated converter,MCC)拥有优异的软开关特性,将是高倍载直流输电系统的优选方案;IGCT-Plus和MCC作为核心器件和装备将支撑具有电压和频率强支撑能力的新型高韧性直流输电系统构建。文中从新型器件、新型装备到新型系统对高韧性直流输电技术进行全面论述,并对后续发展中存在的关键问题和技术进行分析和展望。提出的高韧性直流输电技术对支撑双高电力系统的安全稳定运行具有重要意义,有望成为未来电力传输中的崭新方式。

压控型脉冲功率半导体器件技术及应用

近年来,采用新一代半导体开关替代传统气体或真空开关是脉冲功率系统的一种重要发展趋势。为了给脉冲功率半导体器件领域的技术发展提供参考,简要介绍了压控型脉冲功率半导体器件技术的发展历程,总结了MOS栅控晶闸管(MCT)在器件设计、工艺和可靠性等方面的研究进展,同时通过比较MCT与一般商业IGBT器件,阐述了MCT相比于其他功率脉冲半导体器件的优劣情况,并结合典型应用场景展示了MCT器件的优势,对压控型脉冲功率半导体器件的发展趋势进行了简要分析。

IGCT门极驱动装置杂散电感测量与改进

集成门极换流晶闸管(IGCT)的关断能力高度依赖其门极驱动单元的换流能力,为了提高其换流能力,限制杂散电感是关键。分析了影响关断电路中杂散电感的主要因素,提出了抑制和减小电路杂散电感的方法,采用此方法将关断回路总杂散电感从13.6 nH降低到4.7 nH,最终达到3.5 nH,使门极电流峰值和上升率分别达到-6 120 A和-5 720 A/μs,满足4 500 V/4 000 A IGCT的驱动电路关断能力的要求。对环绕型关断电路的杂散电感进行详细划分和测量,针对采集的各部分电感分布量进行分析,结果对更高电流容量IGCT驱动电路板的设计有重要的参考价值。

基于电容自然充电换相的混合式直流断路器设计与仿真

以晶闸管作为主断器件是降低混合式直流断路器造价和技术难度的手段之一,电容电压是此类直流断路器能够顺利开断直流故障的关键影响因素。现有结构中电容大多为预充电型,但预充电方式和电容电压的维持较为复杂。因此,该文提出一种基于电容自然充电换相的混合式直流断路器,利用母线电压与预充电电容的电压差值实现电容的预充电和电容电压的自动维持,从而保证断路器的开断能力。此外该断路器还具备二次开断能力,可以满足极短时间内重复开断的需求。针对所提断路器的工作过程和元器件参数进行了详细的理论推导,基于PSCAD/EMTDC建立单端等效和四端柔性直流电网模型验证了所提结构的适用性。最后与其他方案进行比较,结果表明,所提方案在开断速度、电容预充电方式和二次开断方面具备一定优势。

脉冲晶闸管热网络模型及运行状态评估方法

针对脉冲晶闸管承受强流脉冲导致的瞬态电磁热力联合冲击产生的热疲劳累积突发性失效问题,提出了在脉冲晶闸管内布置温度传感器的状态监测方法,建立了脉冲晶闸管的高阶瞬态热阻抗网络模型,分析了强流脉冲作用下脉冲晶闸管内部不同层的温度分布规律,并通过理论计算验证了分析方法的有效性。计算结果表明,热网络模型计算相对偏差小于5%。可为脉冲晶闸管型强流开关的状态评估提供理论指导。

面向HVDC应用的逆阻型IGCT关断特性研究

为研究逆阻集成门极换流晶闸管(RB-IGCT)的电流关断特性,指导RB-IGCT换流阀设计,此处搭建了RB-IGCT的电流关断测试电路,对其电流关断特性进行了实测,并采用双指数函数对电流关断特性进行数学拟合。最后基于拟合到的关断电流数学模型,在PSCAD/EMTDC中搭建了IGCT电流关断的器件级功能模型进行仿真测试,仿真和试验结果的一致性表明基于双指数函数的IGCT电流关断模型的准确性,为后续工程应用时IGCT关断电压应力研究以及RB-IGCT阀均压设计提供了快速有效的仿真手段。

晶闸管和IGBT混合的三相电机两相变频控制策略

现有三相交直交变频电路中大多使用IGBT作为电力电子器件,为了进一步降低低压大容量变频器设备成本,减少IGBT的使用,提出了一种晶闸管和IGBT混合的三相电机两相变频电路结构及四开关八电压矢量直接转矩控制策略.首先分析了利用IGBT辅助晶闸管关断的三相电机两相变频电路结构,并分析了不同开关状态下的瞬时电路工作原理,给出三相四开关拓扑下的八电压矢量生成方法;其次提出四开关八矢量异步电机直接转矩控制策略,并给出扇区划分、电压矢量选择和电压矢量伏秒生成原理;最后通过仿真实验验证所提策略的正确性和可行性.仿真结果验证了上述电路结构和控制方法的有效性.

基于晶闸管的电容换相式混合直流断路器拓扑

通过直流断路器切除故障是柔性直流电网中最具前景的故障隔离方法。目前,主断支路串联大量全控型电力电子器件的传统混合式直流断路器存在成本高、技术难度大等问题。文中提出一种基于晶闸管的电容换相式混合直流断路器(Thyristor Based Capacitor Commutation Hybrid DC Circuit Breaker, TCC-HDCCB)拓扑。该断路器通过晶闸管和电容配合完成双向故障换流、断流和自适应重合闸功能且利用直流系统本身对换相电容进行预充电,大大降低了造价和控制难度。文中首先介绍了TCC-HDCCB的拓扑结构、工作原理;然后给出了关键器件参数选取方法;最后在PSCAD/EMTDC4.5软件平台中搭建TCC-HDCCB仿真模型,在单端和四端柔性直流电网中进行仿真验证,并从性能以及经济性与有关方案进行对比分析,验证方案的可行性。

基于IGCT抑制换相失败的关键控制策略

针对基于电网换相换流器的高压直流(LCC-HVDC)输电系统因以晶闸管作为换流器件而存在的换相失败问题,以集成门极换流晶闸管(IGCT)在中国某背靠背高压直流工程中的应用为基础,首先介绍了IGCT型高压直流的拓扑及基本运行原理。接着,从兼顾换相失败抵御效果和IGCT阀的关断应力角度,提出了适应IGCT阀的关断策略。在此基础上,研究了不同类型交流故障对故障电流峰值的影响,提出了利用故障扰动系数动态调整电流控制器参数的策略,实现故障电流抑制和故障期间直流功率的稳定输送。最后,通过实时数字仿真(RTDS)验证了所提策略的正确性和有效性。

西门子SIMADYND交-交变频主传动系统深度保养技术介绍

变频器的维护与保养是确保其正常运行和延长使用寿命的重要环节。通过检查变频器的外部环境、电源及电气连接、散热器和风扇的清洁、绝缘性能的检查以及软件和固件的更新升级等,我们可以有效地管理和保养变频器,提高其可靠性和稳定性。

Analysis and Optimization of the Characteristics of a New IEC-GTO Thyristor

Based on a short anode GTO structure （SA-GTO）,a novel GTO structure called an injection efficiency controlled gate turn off thyristor （IEC-GTO） is proposed,in which the injection efficiency can be controlled via an additional thin oxide layer located in the short anode contact region. The forward blocking, conducting, and switching characteristics are analyzed and compared with an SA-GTO and conventional GTO. The results show that the IEC-GTO can obtain a better trade-off relation between on-state and turn-off characteristics. Additionally,the width of the oxide layer covering the anode region and the doping concentration of the anode region are optimized, the process feasibility is analyzed, and a realization scheme is given. The results show that the introduction of an oxide layer would not increase the complexity of process of the IEC-GTO.

考虑水冷回路的晶闸管换流阀热阻模型建模

结合晶闸管串联水冷回路机构,建立了考虑水冷回路的晶闸管换流阀热阻模型。该模型能够计算出各散热器进水口处的水温,并在此基础上对各级晶闸管的结温进行计算。利用所建模型对换流阀中各组件的热阻进行算例计算;建立稳态热阻模型,对晶闸管结温进行计算。结果表明,考虑水冷回路中冷却液水温差异前后,晶闸管结温计算结果的误差最高可达到10.81%。

用于直流可控避雷器的晶闸管控制单元设计

基于晶闸管的直流可控避雷器是混合级联特高压直流输电系统的关键设备,而晶闸管控制单元(thyristor control unit,TCU)作为其核心开关器件晶闸管的驱动控制装置,对于直流可控避雷器晶闸管的可靠运行起到十分重要的作用。直流可控避雷器的晶闸管工作在高压直流的条件下,其TCU的设计有别于常见的工作于交流电压条件下的晶闸管阀。文中首先介绍了直流可控避雷器的工作原理,接着分析了可控避雷器晶闸管TCU的工作原理,将TCU分为五大电路功能模块,并给出了各个电路功能模块的设计方案,实现了直流工况下晶闸管的触发控制。根据某实际工程直流可控避雷器提出的TCU设计需求,设计了样机,并通过试验验证了设计的合理性。

基于共轭梯度法的晶闸管电热耦合模型快速求解方法研究

为解决传统求解技术在处理效率和计算成本上的局限问题,针对晶闸管电热应力耦合交互模型,提出一种基于共轭梯度法的高效解析方法。通过优化迭代过程和收敛条件来显著提升求解效率和精度。新的参数选择策略被引入以自动调整算法迭代步长,加快收敛速度,减少计算资源消耗。相比传统求解方法,所提优化方法在求解时间上平均减少10%,求解精度提高8%。这一进展证明自适应共轭梯度法在电热应力耦合模型快速求解中的有效性,可为电力电子设备热管理提供高效、可靠的计算工具。所提方法在多种测试条件下均表现出显著的提升效率和良好的精确度,为晶闸管电热耦合模型的高效求解提供了创新方案,同时对电力电子领域的相关研究具有重要的实践意义。

直流输电用特高压晶闸管大气中子失效率评估和损伤机理

本文基于散裂中子源开展了直流输电用8.5 kV/5 kA晶闸管的加速辐照试验。试验证实了大气中子导致的晶闸管单粒子烧毁失效现象,同时基于加速辐照试验结果计算了大气中子导致的晶闸管失效率。晶闸管的反向偏置电压和结温是影响晶闸管器件失效的关键因素。大气中子失效率随着反向偏置电压的增加呈指数增加。此外,失效率随温度的降低而增加。对应器件偏置在50%额定电压下的情况,5℃时的失效率较25℃时增加了近6倍。基于TCAD仿真进一步验证了辐照导致晶闸管失效的机理。仿真表明,单粒子烧毁失效与辐射粒子入射诱发的雪崩击穿效应直接相关。雪崩击穿效应与晶闸管反向偏置电压正相关,而与结温负相关,这与大气中子失效率随电压和结温的变化关系一致。