Study on Transient of Reverse Recovery of Series Thyristors

With more and more applications of devices of Flexible Alternative Current Transmission System (FACTS) and High Voltage Direct Current transmission (HVDC), more and more attentions are paid to the power electronics switches mainly composed of thyristors. Although in published literatures the research on thyristor model and the design of its peripheral circuits are presented, up to now the research on reverse recovery transient of series thyristors has not been reported. Based on exponential recovery current model of thyristor, the transient analysis, mathematical derivation and simulation for the transient of reverse recovery of two thyristors connected in series are performed. Comparison of the results from calculation and simulation shows that the transient analysis by the authors is correct and the assumption for calculation formulae is reasonable to some extend of precision.