Research On Ultra-High-Power Multi-Level Converters With IGCT Devices

This paper describes the IGCT multi-level converter of high power,using the research methods of theoretical analysis,software simulation and engineering experiments.The complete research had analyzed three-level IGCT convertor,gives theoretical analysis formula,researched and designed high power NPC/H bridge five-level converter.Much more research on the buffer absorption circuit,stray inductance,clamping diodes and clamping resistance,overvoltage and overcurrent,dead time in the process of the convert process flow.The power diode characteristic curve is taken as an example in this paper,the study put forward a kind of the function model which has the characteristics of steady-state,forward recovery and reverse recovery,research buffer absorption circuit element parameters and the impact of each branch stray parameters on the IGCT’s turn-on and turn off characteristics using the model.The simulation results show that the model is correct.The three-level IGCT converter commutation process is analyzed in this paper.Much more research on the buffer absorption circuit,stray inductance,clamping diodes and clamping resistance,overvoltage and overcurrent,dead time in the process of the convert process flow is studied,simulation and experiment verify the correctness of the theoretical analysis.This paper study and design high power converter,put forward the topological structure and work principle of IGCT five-level large capacity converter,design the buffer absorption circuit,the precharge circuit,discharge protection circuit,excitation circuit,rectifier transformer and pulse transformer,provides a theoretical basis for converter development.The research and analysis method in this paper is applied on the topic of "the key technology research and engineering demonstration application of large capacity frequency conversion equipment".A five-level converter based on IGCT 20MVA NPC/H bridge is developed,basis on the module switch experiment,large current and trailer experiments,and achieved good results.