Bifurcation phenomena in single-phase three-level inverters

Abstract

Compared with traditional two-level inverter, three-level inverter has the advantages of low output voltage harmonic distortion, and small switch voltage stress, so it attracts more and more attention in high power applications. In this paper, the bifurcation and chaos in a single-phase three-level inverter are studied. The one-dimensional discrete iterated mapping model under proportional control is established, and the stroboscopic maps in different periods of time are obtained. The bifurcation phenomena in the single-phase three-level inverter are studied when the proportional coefficient k, load resistance R, load inductance L and input voltage E are used as changing parameters. Effects of all these parameters on the system dynamical performances are analyzed on a slow scale using the bifurcation diagram and Lyapunov index spectrum. The bifurcation processes on a fast scale caused by changing values of proportional coefficient and load resistance are visually observed using folded diagram. Finally, the time-domain waveforms with different proportional coefficients are obtained by Matlab/Simulink, which corresponds with the theoretical analysis. The results show that the correct circuit parameters of single-phase three-level inverter are very important for its stable operation.