A capability for continuous topology transient analysis in SCR switching-mode power supplies

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Virginia Polytechnic Institute and State University


A general purpose computer model for the SCR is developed. The model, consisting of both a circuit analog and parameter estimation procedure, is uniformly applicable to popular computer aided design and analysis programs such as SPICE2 and SCEPTRE. The circuit analog is based on the intrinsic three PN junction structure of the SCR and is similar to Nienhus' model. The parameter estimation procedure requires only manufacturer's specification sheet quantities as a database. It employs some of the concepts developed by Hu for a SPICE2 SCR model.

This uniform model, denoted the J³ SCR model, is shown to be a useful design aid through computer simulation of fault transients which may occur in a"Schwarz" converter. The transients simulated would not be observable without use of a highly accurate continuous topology non-linear SCR model such as is developed here.