Research On The High Power Five-level NPC/H Bridge Converter With IGCT

The five-level NPC/H-bridge topology is to bring together the advantages of a three-level NPC topology and H-bridge cascade topology, which has the advantage that its control algorithm is simple. This paper research several key issues of the high-power IGCT five-level NPC/H-bridge inverter. In this paper, we analyzed the process of the NPC converter commutation, and establish simulation models of IGCT and diode (including fast recovery diode or hard turn-off diode and soft turn-off diode); while study of the impact of the snubber circuit and stray inductance and power diode switching characteristics to NPC converter device bridge arm of the commutation process deeply, and also study of the IGCTs dynamic and static voltage imbalance in the NPC converter.The focus of the research and the main trunk of this paper is NPC converter bridge arm of the commutation process. This paper analyzes the NPC bridge arm 14 commutation processes; while this paper analysis of the turn-on and turn-off mathematical model of the IGCT devices and established the circuit functional simulation model on PSIM simulation software. Power diode is essential devices for practical applications in power electronics, According to the power diode operating characteristics to calculates its forward-biased and reverse recovery mathematical models, and established the circuit functional simulation model of the power diode based on mathematical models on PSIM simulation software.While this paper research on the impact of the snubber circuit and stray inductance and power diode switching characteristics to NPC converter device bridge arm of the commutation process later. We are establish mathematical model of the commutation process of the snubber circuit state, and study the impact of stray inductance with the commutation process, then we study the impact of the main circuit using the hard turn-off the diodes and soft turn-off diode to commutation process. We analysis the NPC/H-bridge type inverter commutation process, and get the corresponding commutation path and commutation process mathematical models, based on analysis of the NPC bridge arm commutation process,Finally, we research the dynamic and static voltage imbalance problem with IGCT on the NPC converter bridge arm in this paper, and put forward a new type of NPC converter dynamic and static pressure snubber circuit.