Nonlinear Study of Grid-Connected Multilevel Cascaded H-Bridge Inverter

Taking the grid-connected multilevel cascaded H-bridge inverter (MCHI) as the research object, the nonlinear bifurcation chaotic behavior caused by the PI control of the control circuit was analyzed to determine the stable working range of the parameters. Firstly, the discrete iterative mapping model of the system is established by combining the strobe mapping method and the virtual traversal method. Then, the bifurcation diagram was used to analyze the working characteristics of the bifurcation parameter system with the proportional gain coefficient <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">${K}_{\mathrm{p}}$</tex> and the integral gain coefficient <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">${K}_{\mathrm{i}}$</tex>, and then the corresponding stability region was determined, and the stability analysis was completed by using the Jacobian matrix method. Finally, fold diagrams and time-domain waveform diagrams were used to further verify the consistency between the numerical simulation analysis and the theoretical results, providing a reliable basis for the selection of system parameters.