Cascaded PI-Controlled Multistage Boost Converter for Low-Voltage Renewable Sources

High step-up DC-DC converters are essential for interfacing low-output renewable energy sources with higher-voltage power systems. Traditional boost converters, despite their simplicity and wide adoption, face significant limitations in achieving large voltage amplification with high efficiency and stability under dynamic operating conditions. This paper presents a Multistage Capacitor-Assisted Boost Converter (MCABC) that attains high voltage gain at moderate duty ratios, thereby reducing the switching stress and improving the energy transfer efficiency. To address the challenges of voltage regulation in such high-gain systems, a cascaded dual-loop Proportional–Integral (PI) control strategy is implemented, comprising an outer voltage loop for accurate reference tracking and an inner current loop to suppress the inrush and limit the peak current. This control-oriented approach ensures robust dynamic performance and minimal output ripple under varying operating conditions. The experimental validation confirmed both the feasibility of the proposed converter and the effectiveness of the control scheme, demonstrating stable regulation and a fast transient response. The results highlight the suitability of the proposed MCABC for practical deployment in photovoltaic systems, fuel cell applications, and other low-voltage energy platforms that require efficient and reliable voltage elevation.