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Analysis of the transverse heterogeneities in the current density during the thyristor commutation process / Estudo de heterogeneidades transversais na densidade de corrente na comutacao de tiristores

  • Paisana, Jose Julio Alves
Publication Date
Jan 01, 1996
OpenGrey Repository


Our present work is aimed both at the study of the physical principles and conditions underlying the switching operations of thyristors and at the development of a model which is able to describe and predict their dynamic behaviour. our model of the p-n-p-n structure is based on the well-known two-transistors analogy.An extension of this model to include two-dimensoins in space aspects is made and we get a non-linear partial differential equation to describe its temporal and spatial behaviour. Using this approach we discuss the effects and the p-n-p-n regenerative feedback mechanism has on these aspects. The dynamic systems theory, as well the blow-up and the bifucartion theories, were found to be suitable mathematical tools to deal with the problems comming from our modified two-transistor model. In alternative, a finite difference numerical model of the p-n-p-n structure, directed towards obtaining solutions to the basic semiconductor devices equations without any analytical simplification, confirmed many of the results based on the two transistor-model and led to new ones. Among these are the expansion of the high electrical field region from the central junction to the emitters and the dynamic parameters of the structure and, therefore, its electrical switching properties. Particulary for the GTO, it can modify in a significantly way its dynamic turn-off gain and hence the maximum anode current to be interrupted without failure upon application of gate current. The suggestion we present of the substitution of the homojunctions by heterojunctions intends to minimise the dynamic parameters dependence onhe voltage and current at the terminals and, in this way, at improving and ensuring an effective control over the electrical properties of the p-n-p-n structure / Available from Fundacao para a Ciencia e a Tecnologia, Servico de Informacao e Documentacao, Av. D. Carlos I, 126, 1200 Lisboa / FCT - Fundação para o Ciência e a Tecnologia / SIGLE / PT / Portugal

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