Optimized Capacitive Filter Design in DC‐DC Converter Interfaces for Photovoltaic and Fuel Cell Systems

ABSTRACT This paper presents a methodology to design interface capacitive filters between renewable energy sources, such as photovoltaic systems and fuel cells, and DC‐DC converters. The proposal aims to reduce the volume resulting from the filter and improve the efficiency of the system. The modeling considers the non‐idealities of renewable sources, such as resistances, capacitances, and possible inductances, and evaluates the impact of both continuous and pulsed currents supplied by the source. These current oscillations can compromise the maximum power point tracking (MPPT) capability and reduce the energy transferred, as well as increase the volume and cost of the filter. Furthermore, pulsed currents can cause degradation in fuel cells as a result of the generation of double‐layer charges and increased electrochemical stress, reducing the overall lifetime and efficiency. The proposed methodology uses harmonic decomposition to model currents and optimize filter design, along with an iterative process to adjust the capacitance value, allowing a reduction in the input filter capacitance across all evaluated conditions, compared to the conventional approach, and preventing oversizing of the capacitive filter. The experimental validation of the mathematical model and the capacitive filter design confirms the accuracy of the theoretical predictions, presenting a maximum error of 6.48% between the theoretical and experimental measurements.