PhD Urmimala Chatterjee: 'Design and implementation of High Gain Frequency Non-isolated Optimizers for Modular PV Application'
In order to fulfill the increasing worldwide electricity demand, renewable energy sources have long been considered as a very attractive solution. Besides the shortage in the conventional energy sources, rising impact of the global warming and the climate change create the need for an alternative electricity supply with the lowest possible greenhouse gas emissions. Among the other renewable energy sources, photovoltaic (PV) energy is argued to be one of the most promising future clean energy source for its no carbon emission, pollution free operation, low maintenance cost, lack of noise and easy installation. Therefore, the PV energy has been foreseen as a major contributor in the worldwide electricity generation in a near future. Since 2010, the more PV capacity has been installed worldwide than in the previous four decades. The high demand and the several benefits of the PV technology brings the motivation for further research to utilize the solar power more efficiently. The PV research nowadays emphasis on improvement of the system efficiency over a wide range of operating conditions with more cost-effective way than the existing system. By following the trend, this PhD dissertation looks into an efficient way of the PV power conversion by designing and developing the novel power converters to improve the energy yield of the entire PV system. This dissertation proposes high efficient, compact, cost-effective DC-DC converters for the distributed PV application. In the PV power generation, the power loss due to the partial shading is a well-known problem in the prior art. It causes power mismatches between the PV outputs and reduces the total energy yield. To address the power mismatch problem and the fluctuations of the PV output, distributed PV power generations are considered as a potential solution. The benefits of the distributed power generation and the different types of configurations of that are discussed in this thesis. Among different options, DC-DC micro-converters (or also known as DC optimizers) are selected for further research as it is one of the most promising solution. Since DC distribution networks are newly emerging technology in the PV market, DC-DC micro-converters are also useful to integrate in a DC distribution system. In this work, two DC micro-converters are proposed for targeting two different applications, one is mainly for a seriesconnected distributed system and another is for a parallel-connected system. Another topology of a micro-converter is proposed, which is beneficial in terms of its wide input, output voltage range. It will help to track the generated PV power in a wide operating range.