Large Capacity Three-Level Rectifier With Integrated Gate Commutated Thyristors

With the wide application of high voltage large capacity converter, new types of devices and multi-level topology which are characterized by high-voltage and large-capacity start to show their own advantages. Based on the specific studies of three-level IGCT rectifier, this dissertation explores the parameters reasonable design of IGCT rectifier bridge arm, the loss of the bridge arm components, the application of lossless snubber in three-level electric circuit and the re-trigger on IGCT, etc. In order to better guide the design of the converter.Power electronic devices are the basis of power electronic circuits. According to the characteristics of IGCT devices, this dissertation builds an IGCT function model, trying to prove the correctness of this model through the comparison of the waveform between the simulation and the actual devices. Because of the particularity of the IGCT devices, a snubber circuit should be added in the bridge arm. Close analysis of this dissertation on reasonable selection of the parameters of the snubber circuit verifies that the model, by taking an imitative influence of the snubber circuit parameters into consideration, is correct. Due to the fact that the existence of stray inductance in the circuit also has a great influence on IGCT devices, the influence of stray inductance based on device models is also explored in this dissertation.The loss of bridge arm of the three-level IGCT inverter is crucial to the reasonable choice of install capacity of the cooling system. Based on the three-level NPC working principle, analysis of the main switch and diode losses, the detailed calculation of the loss of the snubber circuit and the RC absorb loop at the same time. Not only does this dissertation make an elaborate calculation on the loss of the bridge arm assembly, but also it explores how Energy Feedback Circuit is applied to the three-level by comparing three kinds of typical lossless snubber circuit. And finally, by analyzing the imitative experiments, the advantages and disadvantages of every circuit will be listed in this dissertation.The application of IGCT to the voltage source converter is quite unique because of its specialty. This dissertation argues that it is necessary and important to make the re-trigger of IGCT and analysis of the IGCT re-trigger mechanism based on the analysis of the specialty of IGCT, the principle of switching and the working principle of drive circuit and points out that experiments show internal re-trigger threshold needs to be set reasonably, and propose an experimental program to verify whether to set a reasonable threshold. This dissertation analyzes the working principle and application of internal re-trigger and external re-trigger.Finally, this dissertation describes the development of the3MW/3kVIGCT three-level converter. Due to the symmetry of the circuit, experiments of the double-pulse only to T1and T3.AND the result verify the correctness of the parametric design and theoretical analysis in this dissertation. Through the crossfeed experiments, further validation.