Device modelling and simulation for power thyristor circuits

Abstract

The complexity of considerations in designing circuits using the thyristor has led to the common use of quite generous safety margins to ensure safe and reliable operation. Such conservative designs may lead to costs are losses higher than needed for the application. Moreover, the usul design calculations do not provide very good assurances as to the exact margins that will exist. Even design calculations of the power thyristor circuit are very difficult when the circuit employs nonlinear saturable reactors. These situations can only be improved by using a computer as a tool to aid in the design by executing more detailed and accurate calculations than are feasible without machine assistance. One major vehicle for such computer aided designs is the use of modelling and simulation of the circuit and system in which the devices are to be employed. For a simulatin to be of general value to designers the models used therein must fulfill two basic requirements. They must be sufficiently detailed to adequately represent their behaviors in all important respects and, perhaps even more important, the model user must be able to specify the model parameters from information to which he has ready access. For simulations of the power thyristor circuits with the aid of a computer, this thesis proposes practical device models which fulfill above requirements, and suggests TAPEC as a general purpose simulator enabling to simulate complex power thyristor circuits including not only thyristors but also nonlinear elements. In this thesis, first, a method to determien the reverse recovery current parameters, the peak reverse recovery current and its decay time constant, of the thyristor turnoff model is proposed. Theparameters are extracted from a set of recovered charge curves and another set of reverse energy closs curves given in the data sheets so that the curves may be fitted over a wide range of di/dt at zero current and peak forward thyristor current $I_F$ just before its ...