Module-integrated Converter Based On Cascaded Quasi-z-source Inverter With Differential Power Processing Capability For Photovoltaic Panels Under Partial Shading

Module-Integrated Converter Based on Cascaded Quasi-Z-Source Inverter with Differential Power Processing Capability for Photovoltaic Panels under Partial Shading

Abstract:

            Conventional micro inverter or module integrated converter (MIC)-based photovoltaic (PV) systems are prone to be complex and costly because each MIC requires not only a boost converter to bridge a huge voltage gap between a PV panel and grid but also desirably a differential power processing (DPP) converter to preclude partial shading issues. This paper proposes a novel MIC based on cascaded quasi-Z-source inverters (qZSIs) with DPP capability. A traditional qZSI and voltage multiplier (VM)-based DPP converter are integrated into a single unit with sharing active switches and magnetic components, achieving system- and circuit-level simplifications. In addition, a novel control strategy utilizing two control freedoms of shoot-through duty cycle dst and modulation index M to simultaneously perform maximum power point tracking (MPPT) and DPP function, respectively, is also presented. A 150-W for a standard PV panel consisting of three substrings was built, and simulation results were performed emulating partial shading conditions. The results demonstrated that the proposed integrated qZSI could perform MPPT with satisfactory preventing partial shading issues while generating ac voltage at the inverter output.