Observer-Pattern Modeling and Slow-Scale Bifurcation Analysis of Two-Stage Boost Inverters

Abstract

This paper deals with modeling and bifurcation analysis of two-stage Boost inverters. Since the effect of the nonlinear interactions between source-stage converter and load-stage inverter causes the “hidden” second-harmonic current at the input of the downstream H-bridge inverter, an observer-pattern modeling method is proposed by removing time variance originating from both fundamental frequency and hidden second harmonics in the derived averaged equations. Based on the proposed observer-pattern model, the underlying mechanism of slow-scale instability behavior is uncovered with the help of eigenvalue analysis method. Then eigenvalue sensitivity analysis is used to select some key system parameters of two-stage Boost inverter, and some behavior boundaries are given to provide some design-oriented information for optimizing the circuit. Finally, these theoretical results are verified by numerical simulations and circuit experiment.

Modeling and Stability Analysis of a Single-Phase Two-Stage Grid-Connected Photovoltaic System

“…This time-variance is the main difficulty in stability analysis of the system. To eliminating the effect of time-variance, the system is transformed into a time-invariant one using an observer-pattern modeling method [21,22]. Notice that sin(ωt) and cos(ωt) only exist in the expressions of di o /dt and du c2 /dt.…”

“…The main difficulty for this is that linearization process must be performed around a fixed steady-state operating point rather than a steady-state time-periodic trajectory [18]. To deal with this problem, an observer-pattern modeling method [21,22] is proposed that eliminates the effect of time-variance.…”

Slow-Scale Nonlinear Control of a H-Bridge Photovoltaic Inverter

“…In [8][9][10][11], the essence of the slow-scale instability phenomenon in a voltage-source inverter is analyzed and the analytical expression of the oscillation frequency is derived. In [12,13], the fast-scale instability phenomenon in a voltage-source single-phase H-bridge inverter was studied, and the essence of this phenomenon was analyzed. These studies revealed the profound mechanism of nonlinear phenomena in H-bridge inverters.…”