Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / Este trabalho visa a aplicaÃÃo dos controles robustos D-LQI e D-AlocaÃÃo de polos otimizados via LMIs em um conversor boost de alto ganho de tensÃo com cÃlula de comutaÃÃo de trÃs estados. Este conversor consiste numa topologia moderna derivada do conversor boost clÃssico. O boost à considerado um elevador de tensÃo, o qual converte uma entrada na faixa de 42-54V à 400 V. O conversor boost proposto à reduzido ao modelo de um conversor equivalente e à modelado no espaÃo de estados mÃdio, em que à observado que a matriz D diferente de zero, sendo entÃo uma modelagem que apresenta uma peculiaridade de acordo com a literatura, pois a soluÃÃo de controle à mais complexa. As estratÃgias de controle aplicadas usam de procedimentos matemÃticos denominados de Desigualdades Matriciais Lineares (LMIs-Linear Matrix Inequalities), que podem ser resolvidos por otimizaÃÃo convexa ou programaÃÃo semidefinida positiva (SDP procedures). As ferramentas matemÃticas utilizadas para resoluÃÃo das LMIs neste trabalho sÃo o Yalmip e Sedumi, que sÃo inseridas no MATLAB . AlÃm disso sÃo analisadas as incertezas presentes no processo, bem como a robustez do modelo em malha fechada. SÃo obtidos os resultados de simulaÃÃo via MATLAB -PSIM e sÃo feitas as anÃlises referentes a estes resultados, alÃm da anÃlise dos resultados experimentais e a conclusÃo do estudo, alÃm das propostas de trabalhos futuros. O ApÃndice mostra os procedimentos de instalaÃÃo dos resolvedores alÃm do uso correto com base nas equaÃÃes descritas na teoria sobre LMIs. / This work involves the application of robust controls D-LQI and D-pole placement via LMIs in a high-gain boost with three states switching cell. This converter consists of a modern topology derived the classic boost converter . This boost converter is considered a step-up converter, which a range of 42-54V voltage input to 400V voltage output. The proposed boost converter is reduced to equivalent model and is modeled at space state avarage, in which is observed that the matrix D not equal nought, being then a modeling that presents a peculiarity according to literature, thus the control solution is more complex. The control strategies applied use mathematical procedures called Linear Matrix Inequalities (LMIs), which can be solved by convex optimization or positive semidefinite procedures (SDP). The mathematical tools used to solve the LMIs this work are Yalmip and Sedumi, which are inserted in MATLAB. Further analyzes the uncertainties present in the process, as well as the robustness of closed loop model. The simulation results are obtained via MATLAB and PSIM and analyzes made regarding these results, besides the analysis of experimental results and conclusion of study, in addition to proposals for future work. The Appendix shows the installation procedures and use correct solvers based on the equations described in LMI theory.

abstract: The dissertation encompasses the transformer-less single phase PV inverters for both the string and microinverter applications. Two of the major challenge with such inverters include the presence of high-frequency common mode leakage current and double line frequency power decoupling with reliable capacitors without compromising converter power density. Two solutions are presented in this dissertation: half-bridge voltage swing (HBVS) and dynamic dc link (DDCL) inverters both of which completely eliminates the ground current through topological improvement. In addition, through active power decoupling technique, the capacitance requirement is reduced for both, thus achieving an all film-capacitor based solution with higher reliability. Also both the approaches are capable of supporting a wide range of power factor. Moreover, wide band-gap devices (both SiC and GaN) are used for implementing their hardware prototypes. It enables the switching frequency to be high without compromising on the converter efficiency. Also it allows a reduced magnetic component size, further enabling a high power density solution, with power density far beyond the state-of-the art solutions. Additionally, for the transformer-less microinverter application, another challenge is to achieve a very high gain DC-DC stage with a simultaneous high conversion efficiency. An extended duty ratio (EDR) boost converter which is a hybrid of switched capacitors and interleaved inductor technique, has been implemented for this purpose. It offers higher converter efficiency as most of the switches encounter lower voltage stress directly impacting switching loss; the input current being shared among all the interleaved converters (inherent sharing only in a limited duty ratio), the inductor conduction loss is reduced by a factor of the number of phases. Further, the EDR boost converter has been studied for both discontinuous conduction mode (DCM) operations and operations with wide input/output voltage range in continuous conduction mode (CCM). A current sharing between its interleaved input phases is studied in detail to show that inherent sharing is possible for only in a limited duty ratio span, and modification of the duty ratio scheme is proposed to ensure equal current sharing over all the operating range for 3 phase EDR boost. All the analysis are validated with experimental results. / Dissertation/Thesis / Doctoral Dissertation Electrical Engineering 2017