Observer-Pattern Modeling and Nonlinear Modal Analysis of Two-Stage Boost Inverter

This paper deals with modeling and nonlinear modal analysis of two-stage boost inverter. An observer-pattern modeling method is proposed to eliminate the time-variance effect from both fundamental component in the load stage and 'hidden' second-harmonic one in the source stage. Then, based on the observer-pattern model, the nonlinear modal analysis method is applied to obtain a closed-form analytical representation of the nonlinear system, which yields a great deal of physical insight into the system dynamics. First, fundamental modal analysis is calculated to indicate the correlation between fundamental modes, state variables, and circuit parameters. Such key parameters as C₁ and T₃ are found to be beneficial to the dynamical performance of the whole system. Second, the second-order nonlinear interaction indices are proposed to uncover the underlying mechanism of nonlinear interaction behaviors, and the relationship between modal interaction and system parameters is explored quantitatively. Finally, theoretical analysis is verified by circuit experiments. These results are beneficial to the improvement of transient performance as well as the understanding of the nonlinear interactions in transient behavior.