| IGBT has a high rated voltage,current and switching speed, easy to drive, is one of the best choice of high-power converter applications.With the development of power electronics technology, converter power rating higher and higher, in order to reduce system loss, the research of High-voltage converter is full swing, Such as high voltage inverter and flexible HVDC system. In these applications, tens kV voltage level, single device can't be used in these occasions, Therefore, the research of IGBT series technology has great significance.In the series connection of IGBTs, as the result of the different parameters and the delay of the drive signals, the main problem is unequal sharing of voltage respectively. The devices which withstand over voltage maybe broken down and result in the fault of the whole circuit. Therefore,the core of problem is to ensure dynamic voltage sharing. This article focuses on the active control of voltage sharing technology, including the active clamp technique and active voltage control technique. The second chapter in the analysis technique based on the active clamp, proposed an improved program, and gives detailed descriptions and simulation results to verify the program. In the third chapter and fourth chapter, major study the active voltage control technology, described in detail the working principle, small-signal model and its stability analysis, and through real-time optimal control based on PFGA, for the turn-off losses, diode reverse recovery and other issues to optimize the switching curve, and gives some simulation and experimental results.Finally, the IGBT series technology is applied to the flexible HVDC system of auxiliary power supply projects, Proposed a two level Step-down voltage conversion program, carried out for the first-class Buck step-down circuit for the design and test verification, the experimental results verify the IGBT series technology can be applied to the power electronic converters.
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