Dual-Input Quasi-Z-Source PV Inverter: Dynamic Modeling, Design, and Control

In the conventional photovoltaic (PV) fed quasi-Z (qZ) network-based impedance-source converters (ISCs), the PV array is connected to their input, whereas in the proposed topology in this article, an additional array is paralleled to the second qZ-network's capacitor (C-2). This modification allows harvesting more PV power through full utilization of the employed qZ-network in the classical ISCs. Moreover, the proposal offers higher conversion efficiency since the current in the second qZ-network's inductor ($i_{L2}$) is smaller. The voltage of the added PV array (PV2) is independent of the voltage of the primary array (PV1) in a wide range, which promotes tracking their maximum power points (MPPs) separatly, achieving a higher efficiency even under partial shading. The use of two separate maximum power point trackings (MPPTs) in one converter is a challenge since the perturbation done by the first MPPT alters the power in PV2 as well, and vice versa. Therefore, a two MPPs tracker algorithm, which perturbs two parameters and observes four variables, is proposed for the presented converter. The theoretical analysis is validated through real-time hardware-in-the-loop tests, and it demonstrates that at least 11% more power can be harvested compared to the conventional qZ-network-based ISC.