Modeling and Enhancement for the Current Dynamic Regulation in Energy Stored Quasi-Z-Source Inverter System

Energy stored quasi-Z-source inverter (qZSI) combines the advantages of qZSI and energy storage technology. The energy storage units (like battery or ultra-capacitor) are utilized to reduce the power fluctuation in the PV and fuel cells systems based on the qZSI topology. This paper focuses on the theoretical analysis of the dynamic regulation for the embedded energy storage units. By modeling with the battery and corresponding eigenvalues analysis, the low damping ratio issue related with the battery internal resistance is found to be the key obstacle for the dynamic process improvement. The resulted bandwidth limitation on the conventional PI type current controller is explored mathematically. An enhancement based on the active damping technique is then proposed. The bandwidth gets extended and better dynamic performances are achieved. The theory and design method are verified by the simulations and experiments.