Sharif Digital Repository

Power factor correction (PFC) converter circuits are non-linear system due to the contribution of their multiplier. This non-linearity reflects the difficulty of analysis and design. Models that reduce the system to a linear system involve considerable approximation, and produce results that are susceptible to instability problems. Our goal is to design a controller that achieves some performance specifications despite these uncertainties in modeling. This paper addresses a robust H∞ control problem for switched circuits with parameter uncertainties. The necessary and sufficient conditions for existence of strong robust H∞ dynamic compensators and static output feedback controllers are... 

Agent-oriented software methodologies have found their way to become one of the most important issues of software development. The diversity of existing methodologies and the variety of newly arriving ones have arisen the question of which methodology is best in the context of a special problem, so the need for evaluating and comparing methodologies is becoming more important everyday. On the other hand evaluating methodologies can reveal their strengths and shortcomings which lead to an improvement in development of the next generation of agent-oriented methodologies. In this paper, we are going to introduce an approach for evaluating methodologies via the evaluation of their lifecycle... 

In this paper, a dual-frame hybrid vector control (DFHVC) of vector-modulated VIENNA I rectifier is proposed. The purpose of this novel vector control system is not only to reduce second-order harmonic pulsation on the dc-side and consequently, to reduce odd-order harmonics on the ac side of VIENNA I rectifier under unbalanced mains, but also to ensure a near unity power factor operation of the rectifier under such circumstances. To serve this purpose, at first, a mathematical model of the VIENNA I rectifier under unbalanced condition is derived. In this model, besides demonstrating the nonlinear nature of the DC-link voltage dynamic, a new set of equations for current reference generation...