In this paper, the dynamical behavior of a full bridge DC–AC buck inverter controlled by fixed frequency and PWM is studied. After showing that the system can undergo both period-doubling and Neimark–Sacker bifurcation at the fast scale (switching period) by using the exact switching model, an exact solution discrete-time model able to predict both instability phenomena is derived. The model is obtained without making the quasi-static approximation and it can be used to obtain the useful operation region in the multi-dimensional design parameter space from time domain simulations in a very fast and accurate manner. Based on the study of the system, some design guidelines are provided. Copyright © 2010 John Wiley & Sons, Ltd.