Multi-Objective Cascaded Controller Design for Multi-Output DC-DC Converter in Grid-Connected PV System

Abstract

As renewable energy becomes increasingly essential to global energy strategies, grid-connected photovoltaic (PV) systems are gaining prominence. However, these systems introduce challenges related to power quality and system stability. This paper presents a unified nonlinear cascaded control strategy tailored for a multilevel single-input dual-output (SIDO) boost converter-based grid-connected PV system. The proposed approach is aimed at integrating the sliding mode control (SMC) for both maximum power point tracking (MPPT) and power factor correction (PFC) tasks, while a filtered proportional-integral (PI) controller is employed to stabilize DC voltage regulation. This combination control framework ensures these objectives under varying environmental conditions, all while taking advantage of multilevel conversion, such as reduced component stress and high voltage gain without transformers. Simulations studied within the MATLAB/Simulink environment confirm the proposed approach effectiveness, demonstrating reliable performance and enhanced improvements in system stability compared with the widely conventional approach.