Nonlinear dynamic behavior analysis of photovoltaic quasi Z-source inverter

Compared with the traditional two-stage boost inverter, the quasi-Z-source inverter can achieve boost under the condition of direct current, and the single-stage structure can achieve two-stage functions, so it can improve the reliability and transmission efficiency of the photovoltaic system. This paper studies the nonlinear dynamic behavior of single-phase photovoltaic quasi-Z-source inverter under unipolar SPWM modulation.Firstly, according to the working principle of quasi-Z-source inverter, the state equations of the system are derived. Based on the state equations, the accurate discrete iterative mapping model of quasi-Z-source inverter is established. Then, the nonlinear dynamic behavior of single-phase quasi-Z-source inverter under different proportional coefficients is analyzed from the perspectives of folding diagram, bifurcation diagram and folding phase diagram. The time-domain waveform obtained on the Matlab/Simulink simulation platform verifies the correctness of the theoretical analysis. Finally, the waveforms and conclusions obtained by the experiment are consistent with the waveforms and conclusions obtained by the simulation. Therefore, this study has certain theoretical significance for deeply understanding the working stability of single-phase photovoltaic quasi-Z-source inverter, and also has certain practical engineering value, which provides a theoretical basis for the design of the main circuit and control circuit of the system.