论文以基于集成门极换流晶闸管（IGCT）的二极管中点箝位（NPC）三电平变换器为研究对象，摆脱理想器件模型和集总参数束缚，建立适用于瞬态换流分析的变换器主回路模型，定量描述杂散电感对瞬态换流特性的影响，提出可有效应用于实际变换器的母排和最小脉宽设计方法，从而实现大功率电磁能量高效和高可靠性的变换。半导体器件和变换器母排模型是构建变换器瞬态分析模型的关键和难点。论文提出一种有效结合功能模型和集总电荷模型特点的快恢复功率二极管混合模型，使模型精度、计算速度以及模型参数求解难度达到有效“折中”。模型采用四个阶段描述二极管反向恢复过程。仿真结果与产品手册数据、实验波形对比表明所提模型能够准确描述标准和非标准工作条件下的二极管开关特性。基于IGCT的三电平变换器母排具有尺寸大、结构复杂及强非线性时变电路拓扑等突出特点，目前并无成熟应用于该类母排分布参数的提取方法。针对此问题，论文提出采用部分元等效电路（PEEC）法、阻抗特性测量法以及IGCT关断特性测试法相结合，以获取准确的母排分布参数，建立适用用电路仿真的母排等效电路模型，从而构建了完整的变换器瞬态分析模型。模型仿真结果与测试结果基本一致，表明所提模型可有效地应用于变换器瞬态换流的研究通过对受杂散电感影响的变换器瞬态换流特性的全面分析，提出“杂散电感影响因子”的概念，评估杂散参数对电压峰值和稳定时间等重要特性指标的影响程度，据此提出杂散电感的设计原则，为变换器的器件选型和结构设计提供实际参考指标。基于对变换器主回路杂散电感及瞬态换流的研究，论文提出变换器低感和低影响的母排分析和设计方法，并将此方法应用于实际系统中，提出一种新的两层层叠母排结构，仿真和实验结果表明，与原有三层层叠母排结构相比，该母排的分布电感及其影响都大幅度减小；此外，通过对受死区影响的各种瞬态换流情况的研究，提出一种简单实用的最小脉宽实验测定方法，使最小脉宽设计在保证系统安全运行同时尽量减小其影响。

IGCT-based diodes neutral point clamped three-level converters are studied. Main circuit models suitable for transient analysis are developed, which avoid the ideal devices’ models and lumped parameters. The influence of stray inductance on transient characteristics is described quantitatively. Busbar and minimum pulse width design methods are put forward and applied in a practical three-level converter to obtain high efficiency and high reliability electromagnetic energy commutation. The modeling of semiconductor devices and busbar are the key problems for the transient commutation analysis. A new hybrid model of fast recovery diode is proposed, in which lumped charge model and functional model are combined to obtain a simple and accurate simulation. In the model, the reverse recovery is described by four stages and the forward recovery considers the “inductive effect”. The simulation results are consistent with the ratings of product and experimental results, which prove that the hybrid model of the fast recovery diode is suitable for the circuit simulation.The busbar of IGCT-based three-level converter has large size, complex structure and strong nonlinear time variable circuit topology. At present, mature distributed parameters extraction methods applied to such busbar are still not existed. Three kinds of techniques including partial element equivalent circuit (PEEC) computation, impedance measurement and IGCT turn-off characteristics test are employed to extract distributed parameters of busbar. Then, the equivalent circuit of busbar is developed and a full transient analysis model of converter is achieved. The model is verified by the comparison between simulation and experimental results.Through comprehensive research on the transient commutation process influenced by stray inductance, influential indexes are introduced to evaluate the influence of stray inductance and design rules that take the stray inductance into account are proposed, which provide practical guidelines for the components selection and converter structure design.Based on the commutating process analysis of three-level converter, a low-inductance and low-effect design method of busbar is proposed and a new laminar busbar structure with two layers is developed. Simulation and experimental results prove the validity of the bus bar design. Compared with original busbar structure with three layers, the inductance and the induced voltage peak of the improved busbar are reduced greatly. Furthermore, a simple and practical method to determine the minimum pulse width is presented, which guarantees reliable operation of switches and minimize the negative impact.