Abstract This paper proposes a nonlinear average model of three levels NPC inverter. This model takes into account the semiconductor non-linearity and static characteristics of these devices. The proposed technique uses experimental results to evaluate the different devices parameters. The developed nonlinear average model allows dissipated power and junction temperature evaluation. Unlike the circuit model (fine model), the proposed method has less computational burden. It can be applied to three levels Neutral-Point-Clamped inverter (NPC).