Study on bifurcation and chaos in single-phase H-bridge inverter modulated by unipolar sinusoidal pulse width modulation

Abstract

The unipolar SPWM has been widely used in H-bridge inverter because of its superiority for lower switching loss and less electromagnetic interference as compared with bipolar SPWM. However, the nonlinear phenomena in it have not been reported. In this paper, the bifurcation and chaos in the H-bridge inverter modulated by unipolar SPWM is studied. The one-dimensional discrete iterated mapping model under proportional control is established. Effects of the proportional coefficient k on the system performance are analyzed by using bifurcation diagram, folded diagram, and Lyapunov index spectrum. The time-domain waveforms with different proportional coefficients are obtained by Matlab/Simulink, which verify the correctness of theoretical analysis. Finally, the nonlinear behavior in the inverter caused by the variation of other circuit parameters like input voltage E, load resistance R, and inductance L is investigated through bifurcation diagrams. This paper turns the chaotic research of single-phase H-bridge inverter from bipolar SPWM to unipolar SPWM, So that the proposed approach is more practical. The results have important guiding significance and application value for designing and debugging the single-phase H-bridge inverter correctly.