Fast-scale period-doubling bifurcation in voltage-mode controlled full-bridge inverter

This paper describes the fast-scale bifurcation phenomenon of a voltage-mode controlled full-bridge inverter which is widely used in AC power supply applications. Main results are illustrated by exact cycle-by-cycle circuit simulations. It is shown that the fast-scale bifurcation phenomenon is a type of local instability which manifests itself as period-doubling for some intervals within the line cycle. It is also observed that such fast-scale instability always takes place around the middle of every half line cycle, where the reference output voltage reaches the maximum or the minimum. Moreover, an improved discrete-time model is used to theoretically analyze the fast-scale period-doubling bifurcation. Our work presents the discrete-time approach in modeling switching converters, and provides an convenient means of predicting stability boundaries so as to facilitate the design of inverter.