Design and Development of Dual-Input Dc - Dc Converter Based Hybrid Power Supply System for Telecom Load

Abstract

Telecommunications has become an imperative part of our life day-to-day activities from education to business. Power supply reliability is a critical challenge for telecommunication industries due to the deteriorating of fos- sil fuels with rising power demand. In most cases, telecom towers rely on diesel generators as a basis of power generation, which emits pollutants and is rather expensive. Due to climatic conditions and decreasing cost of solar PV panels, combination with biomass power, this technology could be used to provide clean electricity to various remote locations telecom load, where grid is not available. The proposed system will satisfy to afford reliable power supply for telecom load by completely eliminating the grid and diesel generators. This study emphasis on interactive based hybrid power supply solution for telecom load. An appropriate utilization and management of the PV/Biomass/Battery energy sources aids in greater reliability and enhanced efficiency of the system. Consequently, a litera- ture review pertaining to multi-input converter topologies, Bidirectional DC-DC converter and voltage regulation technique have been presented. Therefore, research in this thesis focuses on integrating energy systems suitable for telecom load use with sustainable power generation technolo- gies, such as biomass power and photovoltaics. Among the research areas addressed in this perspective are dual-input DC-DC converter configura- tions, modelling and control strategy of the converter topologies, means for storing energy, Bidirectional DC-DC converter and voltage regula- tion technique. The multiport system structure is proposed as a means of integrating primary sources and energy storage. An integrated power conversion is possible by utilizing only one power processing stage in com- parison to the conventional structure that utilizes multiple converters. Power conversion for a hybrid power source is integrated using a single power stage to interface multiple power inputs. In contrast with the con- ventional techniques that utilises multi-input converters, this structure eliminates redundant power stages. Thus, this study focuses on devel- opment of dual-input converter for providing power supply to meet the requirement of telecom load. The implementation has been concentrated von developing a dual-input converter topology with charging the battery. Three converter topologies were realized. The first converter topology is modular dual-input full-bridge DC-DC step-down converter, in which both the output of the secondary rectifier are connected in parallel structure. The converter provides power supply to both telecom load and simultane- ously charge the battery. Second converter is modified modular dual-input Full-Bridge step-up DC-DC converter. The converter has two individual input modules with three-leg semi active rectifier connected in parallel at secondary side for achieving constant voltage across the load with re- duced circulating power. Further, third converter is modular dual-input half-bridge DC-DC converter. The prsented converter has two individual input modules with three-leg active converter connected in parallel at sec- ondary side. Further, a bidirectional buck-boost converter with only two active switches to charge and discharge the battery has been investigated in this research. The presented topologies results in an advantage of hav- ing compact structure with reduced number of components. The complete design and steady state analysis of the converters have been investigated. There have been several improvements for the presented converter topolo- gies aimed at zero voltage switching, reduced current stress, and greater efficiency in order to take into account the specific operating character- istics of the renewable energy sources with energy storage devices. The developed converter configurations have been tested with laboratory pro- totypes. The performance of the converters was investigated for a closed- loop control implemented with FPGA based digital controller. The power flow in the system is proved to be controllable. A significant enhancement in the efficiency when using the zero voltage switching and voltage power balance control method is witnessed. Further, telecom load functions in a pulsed-power manner intermittently. Moreover, the power consumption will be determined by signal traffic. The major task during pulsed power operation, is to maintain the regulated voltage across DC load terminals. Hence, in this study, Type II compensator is developed to maintain the constant load voltage with reckless response time. The stability investi- gation of the system with Type II compensator is evaluated by utilising the MATLAB/Simulink tool.