A PHYSICAL AND CIRCUIT LEVEL APPROACH FOR MODELING TURN-OFF CHARACTERISTICS OF GTOS

In this paper, we present physical and circuit models, which are relat ed via their parameters, to characterize the gated turn-off characteri stics of thyristors. The physical model provides physical insight to t he mechanism of turn-off in single islands, and investigates analytica lly, the dependence of storage time on external variables (anode and g ate currents) and physical device parameters and dimensions. Such a ch aracterization is useful since the current crowding effect (that limit s current controllability in a multiemitter structure) depends on the turn-off behavior of the unit cells. The circuit level approach provid es a model which can be incorporated into CAD programs (such as SPICE) that can be used by application engineers to design a variety of powe r electronic circuits such as Static Var Compensators (SVC's). The par ameters of the circuit model are based on the physical model parameter s and thus reflect the physical device properties and dimensions.