Fast-Scale Bifurcation Analysis in Current-source Inverter

This paper discusses the fast-scale instability in the current-source inverter which is an attractive topology in the photovoltaic power system for its better efficiency. Simulations show that the fast-scale instability which occurs around the peak value of the inductive current is a type of local instability. An improved discrete time model which can solve the problem existing in the traditional modeling method that the coefficient matrix of the system state equation is noninvertible is derived to analyze the fast-scale instability, the theoretical analysis shows that the fast-scale instability manifests itself as a period-doubling bifurcation occurs, which reveals the intrinsic mechanism of the current-source inverter. Furthermore, with the discrete-time model the stability boundary is obtained which is helpful to select the proper values of parameters for avoiding the fast-scale instability. It is shown that the analysis method is useful for the design of the current-source inverter.