Conversor buck-boost bidirecional híbrido a capacitor chaveado ressonante para processamento diferencial de potência em sistemas fotovoltaicos

Abstract

In most practical applications, photovoltaic (PV) modules should be connected in series to reach a desired voltage level for a specific application. An important problem that frequently affects this type of connection is mismatch among the modules. It can be caused by several factors that can be classified into permanent or temporary. To mitigate this problem, bypass diodes are the most widely used technique owing to its simple implementation. However, this technique is only appropriate for temporary mismatch. In permanent mismatch, more sophisticated mitigation techniques are required. In this context, the concept of differential power processing (DPP) has emerged as a prominent solution for permanent mismatch owing to its low cost, simple implementation, and high performance. For this purpose, DC-DC converters, named DPP converter, are connected between the adjacent PV modules. The way these DPP converters are connected along the PV series originates four main architectures: PV-PV, PV-Bus, hybrid, and ladder. In this way, the aim of this study is to develop and implement a novel topology named BBBReSC. It consists of a hybrid architecture that incorporates elements from both BBB and SC converters. Notably, it tackles key challenges that impact the PV-to-PV and PV-tovi Bus architectures. Specifically, it addresses issues like the diverted current accumulation in the PV-to-PV architecture and high voltage stresses associated with the PV-to-Bus architecture. Another important issue is that the hard-switching operation of semiconductors in SC converters may lead to high switching losses and poor efficiency. In turn, the introduced solution referred to as ReSC converter provides operation under soft-switching conditions while mitigating such undesirable losses. To demonstrate the effectiveness of the BBB-ReSC topology, tests using PV strings composed of four, six, and, eight FV modules were conducted. These tests were performed through simulations in MATLAB/Simulink® environment, as well as with the use of an experimental prototype. The experimental results have shown an improvement in harvested energy of up to 50% for the PV string consisting of four modules and 33% for the PV string with six modules.