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In this paper, a systematic and analytical study of non-isolated topologies belonging to the family of reduced redundant power processing (R2P2) converters is presented. Based on this study, all the non-isolated R2P2 topologies that can be implemented in reality are derived. Detailed examples clarify all possible cases of this analysis. In addition to this, the voltage ratio and the efficiency for each one of the R2P2 configurations are calculated, being further illustrated with examples. A comparison among configurations is also discussed with criteria the high step-up voltage gain and efficiency, aiming for high-power applications. One of these R2P2 converters is selected for further examination, as the most suitable for such applications. The theoretical analysis, as well as the calculations of the step-up voltage ratio and efficiency of the selected converter, is compared to experimental results conducted on a 2-kW laboratory prototype designed to operate in various step-up voltage ratios and in a high-power range, proving the effectiveness of the proposed investigation. [ABSTRACT FROM AUTHOR]

The current-source flyback inverter has been proven an excellent solution for ac–PV modules. The two principal modes of operation of this converter are the discontinuous conduction mode (DCM) and the boundary conduction mode (BCM). Although BCM offers higher power density, it suffers at lower power levels, because of the significantly increased switching frequency that consequently leads to higher switching losses and lower overall converter efficiency. In this paper, a hybrid operating mode is presented, that combines both DCM and BCM during a utility grid period, so as to improve the converter performance as well as the efficiency and the power density on a wider power range. The mathematical analysis that describes the control specifics especially for a smooth transition between the two modes of operation is presented and demonstrated through computer simulations and experimental results on a laboratory prototype. [ABSTRACT FROM AUTHOR]

The flyback topology is proven to be a very strong candidate solution for use in ac-PV module applications. Operation in the boundary condition mode (BCM) provides high power density, while maintaining the characteristics of a current source inverter. In this paper, a design methodology is presented, that maximizes the weighted efficiency of the converter through an optimization algorithm. The inverter operation is investigated and the behavior under the improved BCM is documented by analytical equations followed by the power loss calculations for each component. This enables to accurately define the relation between the design parameters and the efficiency of the implemented converter and so, an optimization algorithm is established, that takes into consideration the design specifications and constraints. The proposed methodology is also verified with an experimental prototype. [ABSTRACT FROM AUTHOR]