Modeling thyristor and diodes; on-state voltage and transient thermal impedance, effective tools in power electronic design

Circuit modeling is an essential tool in the design of power electronic applications. Both the onstate forward voltage drop and transient thermal impedance of high power SCRs and diodes are complex functions. The main objective of this paper is how to use modeling equations to evaluate a given power electronic application. The forward on-state forward voltage drop can be modeled by both the classical ABCD and the new MNOP...parameters. The transient thermal impedance has been shown to be well represented via four or five exponential terms representing the significant transient thermal time constants of the device. Both the digital (hard code) simulation and “analog” PSPICE simulation techniques are described. Also, a new tool, called STARSim, is described. STARSim permits comparison of the older superposition method and new modeling method by performing the calculations using both approaches. A simple SCR model for PSPICE incorporating the on-state forward voltage drop and transient thermal impedance models is also described and evaluated. This information is considered to be important in providing the tools required for power electronic design engineers to quickly evaluate a given device in proposed or existing power electronic application