Non-linear properties and efficiency improvements of a bi-directional isolated DC-AC converter with soft commutation
ABSTRACT This paper presents the operation principle and the properties of a single-phase DC-AC converter with medium frequency transformer and soft commutation. The influence of the non-dissipative snubber capacitor and the transformer parasitic components for ZVS and ZCS are explained in relation with their influence of the output characteristic. Additionally the effect of the semiconductor voltage drop is considered to get a precise circuit model for steady-state continuous operation. Finally efficiency improvements of this phase-shift PWM DC-AC converter are achieved by actively short-circuiting the circulating current at the AC-side during full load operation.
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Article: Microgrids Performance Challenges[Show abstract] [Hide abstract]
ABSTRACT: Nowadays the concept of the more efficient distribution and generation is widely explored. According to that distributed generation and the concept of microgrids have been proposed. However distributed generation and microgrids themselves have their own major influence on the grid: making conventional protection and automations solutions obsolete, introducing new requirements for equipment and planning. The new approaches are required. A number of problems as well as proposed solutions are introduced in this paper. The direction of future researches is denoted.
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ABSTRACT: This paper presents a novel modulation for a two-stage dc-ac power converter with high-frequency isolation installed in a photovoltaic stand-alone system. The presented modulation, which is designed for the converter discontinuous conduction mode of operation, solves the problem of connection to a grid, and permits a bidirectional power flow. In this document is described the modulation strategy and some simulation and experimental results are presented.Power Electronics and Applications, 2009. EPE '09. 13th European Conference on; 10/2009