Quasi-Z source inverter with battery based PV power generation system

A new PV power generation topology, based on the quasi-Z source inverter (QZSI) with battery, is proposed in this paper. With a battery paralleled with one of the capacitors, this system can smooth the grid-injected/load power when the PV panel outputs a variable power with fluctuations. The battery can be charged or discharged without any extra circuit, because of the unique impedance network of QZSI. The operating principle and power flow of this system are analyzed. The closed-loop control strategy is used to achieve Maximum Power Point Tracking (MPPT) and keep the output voltage stable. Three operating modes of the proposed PV power generation system are simulated in the MATLAB/Simulink to verify its principle and theoretical analysis. A prototype is built in the lab, and the experimental results validate the whole system.