Conversores CC-CC sepic-zeta multi-braços, com modução PWM intercalada, aplicados à mobilidade elétrica e eletrolisadores de hidrogênio verde

Abstract

This thesis presents two DC-DC converter topologies. The first converter is denoted as a highefficiency, multi-device interleaved bidirectional SEPIC–ZETA DC-DC converter, intended for electric mobility applications. This converter offers several key advantages, including reduced current and voltage ripple on both the input and output sides, achieved through a ripple Frequency at the terminals that is six times higher than the switching frequency. Additionally, the required volume of magnetic components and capacitors is significantly reduced, since the inductor current ripple occurs at twice the switching frequency, resulting in lower power losses, reduced stress on power devices, and higher efficiency. The use of a multi-device structure enables more efficient optimization of inductor volume and provides greater fault redundancy. To validate the proposed topology, a 5 kW laboratory prototype was developed and tested over a wide range of load conditions, with port voltages of 220 V (V1) and 450 V (V2). The experimental results confirmed the high performance of the converter, achieving a maximum efficiency of 98.6% at rated power. The second converter is denoted as a Multi-Arm interleaved ZETA DC-DC converter with parallel switch modulation, intended for electrolyzers powered by renewable energy sources. The proposed converter exhibits low current and voltage ripple, reduced power losses, and decreased magnetic volume. The use of parallel switches, combined with the interleaved PWM technique, simplifies the design and enhances performance without requiring the inductors to scale proportionally with the number of arms. Among the main benefits, the current and voltage ripple frequencies at the electrolyzer are six times higher than the switching frequency, while the output capacitor current ripple frequency is also six times higher than the switching frequency. Furthermore, the ripple frequencies of the inductor current and the coupling capacitor current are twice the switching frequency, allowing for a significant reduction in the volume and mass of passive components, thereby increasing power density. A 6 kW proof-of-concept prototype was experimentally tested with a 480 V DC bus voltage and a 250 V electrolyzer voltage, demonstrating a maximum efficiency of 98.16%, as confirmed by experimental results. In addition, this thesis presents the steady-state operating principles under continuous conduction mode, design guidelines for parameter selection, comprehensive mathematical derivations, and a comparative analysis with existing DC-DC converters.