Integrated dc-dc converter for photovoltaic energy harvesting targeted to indoor applications

• Ano de defesa: 2020
• Autor(a) principal: Silva Júnior, Luiz Antônio da
• Orientador(a): Girardi, Alessandro Gonçalves
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Universidade Federal do Pampa
• Programa de Pós-Graduação: Mestrado Acadêmico em Engenharia Elétrica
• Departamento: Campus Alegrete
• País: Brasil
• Palavras-chave em Português: Engenharia elétrica; Internet das coisas; Dispositivos eletrônicos; Electrical engineering; Internet of things; Electronic devices
• Área do conhecimento CNPq: CNPQ::ENGENHARIAS
• Link de acesso: http://dspace.unipampa.edu.br:8080/jspui/handle/riu/5465

Internet of Things (IoT) is a current great trend in which the number of connected devices to the Internet increases over years, thus facilitating the monitoring and control of outdoor and indoor environments. In addition, the majority of electronic devices, mainly peripherals, are used most of the time indoors like office rooms, for example. These devices are usually power supplied by wiring or batteries. The use of wires can sometimes compromise the practicality of some electronic devices, and batteries must be frequently replaced or recharged. Energy harvesting is a great solution to overcome this problem, since the energy provided by the environment, such as lighting, can be harvested by a photovoltaic (PV) cell in order to power supply electronic devices and IoT sensor nodes. The power harvested by PV cells indoors is still quite limited, therefore energy harvesting systems in this type of environment are not widely exploited and target only low power applications. A PV cell may suffer shading caused by walls, furniture, and human movements. This requires an efficient conversion system that can adapt to the PV cell output voltage variations. In this context, the present work aims to propose an integrated conversion system for indoor light energy harvesting to partially replace battery usage in electronic devices and ultra-low-power (ULP) circuits. For the system block responsible for voltage conversion, we propose a reconfigurable DC-DC converter topology based on Switched Capacitor (SC) capable to providing a range of voltage conversion ratios (VCRs). A systematic simulation-based method is also proposed in order to design the conversion system, including switches and capacitors sizes and switching frequency. Results show that the proposed DC-DC converter can adjust itself to achieve 19 different VCRs including fractional, integers, step-down, follower, and step-up with an estimated peak charging efficiency around 90%. In addition, the conversion system can be employed in a vast range of duty-cycled ULP IoT applications. This is an important step towards a practical self-powered indoor system for IoT applications.