Research On The Unbalancing Dynamic Voltage Of Serial Press-contact IGBT

High-voltage direct current flexible has played an increasingly important role in the field of Long-distance transmission,Renewable energy, Urban Distribution Network and Distributed generation. The converter is the core component of HVDC transmission system. With the development of power electronic technology, Voltage source converter based on IGBT began to be widely used in the field of HVDC-flexible. Because of the DC voltage grade in HVDC-flexible system is far greater than the rated voltage of IGBT, In order to realize the high power output, The technology IGBT series plays a vital role. The technology IGBT series wish for a good consistency of IGBT action, But there are many factors which will cause voltage unbalance, When severe, will cause the IGBT breakdown. Therefore, to ensure the safe operation of the inverter, the researching on the influence factors and the techniques of IGBT series connection has great significance.In order to solve the voltage unbalance problem of series IGBT, this paper propose a modeling method of press IGBT, then analyses the influence factors which cause voltage unbalance. Besides, according to the analysis of the RCD active gate control, the parameter selection strategy of the RCD circuit is proposed.First, according to the operational principle of IGBT, the behavior model of IGBT are built using the saber software, The parameters selection strategies and validation methods are investigated in details.Next, based on the circuit of two series IGBT, the influence factors of unbalanced voltage in the series IGBTs are summarized, the quantitative method of influence degree on the unbalanced voltage in series-connected IGBT is proposed.Then, this chapter is aimed on a valve section of the voltage source converter, and established its equivalent circuit, then the unbalance voltage of the valve section was analysed.Finally, according to the analysis result of influence factors in the series IGBTs, the equalizing effect of the RCD active gate control is analysed, the parameter selection strategy of voltage balance circuit is also posed. The effectiveness of the strategy is validated though simulation results.