Analysis and control of quasi-Z source inverter with battery for grid-connected PV system

► A new topology—a qZSI with battery for PV power generation system. ► Energy storage device is introduced without adding an extra DC/DC converter or an extra DC/AC converter. ► The first study showing the parameter design method for the battery-based qZSI PV system. ► The battery-based qZSI PV system can effectively smooth the grid-injected active power. The quasi-Z-source inverter (qZSI) has some unique advantages and is suitable for photovoltaic (PV) system. This paper proposes a new topology—a qZSI with battery for PV power generation system. Battery is paralleled with one of the capacitors in quasi-Z-source (qZS) network, instead of an additional DC/DC converter. This system inherits all the advantages of qZSI. Besides, with a battery, the system can smooth the grid-injected power when PV power fluctuates. The operating principle of the new topology is analyzed and the design scheme of the qZS network is presented. And then, closed-loop control strategy for the proposed system is designed to manage the three power flows of PV panel, grid, and battery in the system. Maximum Power Point Tracking (MPPT) has been implemented in the qZSI with battery-based PV system by using the proposed control scheme. Different operating modes are simulated. A small-scale power prototype with a real PV panel is built to test the proposed system. The simulation results and experimental results verify the proposed circuit, theoretical analysis, and the control scheme.