This paper presents the results of analysis and simulation of the static characteristics of IGBTs with a buffer n'-layer. In their investigation, the authors have used the “Issledovanie” software package intended for numerical simulation of the static and dynamic characteristics of silicon power devices. This program is based on the numerical solution of the fundamental set of equations taking into account the total amount of physical phenomena (electron-hole scattering, dependence of lifetime and mobility on doping concentration, band-gap narrowing, Auger recombination etc.). The authors also present the results obtained within a simple analytical model.