This paper describes a novel family of single-phase single-stage buck-boost inverters using output unfolding circuits. Operation principles, component design guidelines along with modulation techniques are presented and discussed. The simulation results confirm all theoretical statements. Experimental setup of the most promising solution is assembled and tested, where the efficiency for different operation modes is analyzed. Finally, the pros and cons along with applications of the proposed solutions are discussed in the conclusions.

This article presents a novel concept of a universal solar converter suitable for application in both in the dc or single-phase ac grids using the same terminals. The idea lies in the utilization of the same semiconductors in the dc–dc and in the dc–ac configuration, resulting in minimal redundancy. Possible semiconductor stages are considered. The particular attention is focused on the output filter design along with proper protection circuit selection for dc and ac grids. The design example and comparative analysis between dc–dc, dc–ac, and universal solutions are given. The experimental prototype of the universal solar converter that is rated for 3.6 kVA power in the ac mode and 5 kW in the dc mode is presented. The experimental results demonstrate the ability of operation in ac or dc grids with main correspondent modes. Possible fields of application along with main benefits are addressed in conclusions.

In this paper comprehensive evaluations of isolated high step-up dc-dc topologies have been investigated. These converters are especially well suited for distributed generation systems utilizing renewable or alternative energy sources that need a wide input voltage range with load regulation. With this in mind, this work primarily concentrates on comparative analysis of various isolated configurations employed in possible industry applications. Consequently, several isolated structures, including flyback, forward, push-pull, and full bridge and other similar solutions have been carried out in the literature. For the purpose of comparative and theoretical analysis, some of the circuit parameters are considered, which include voltage conversion ratio, semiconductor element voltage stress, component size, and conduction and switching losses. Furthermore, the selected configurations have been discussed in terms of cost estimation and financial feasibility. In addition, the design procedure and experimental prototypes of the available solutions with the main results are presented. Derived from this investigation, the authors provide a guide to help researchers to identify different isolated topologies with wide input voltage range and galvanic isolation for prospective research directions within this area

There is a growing interest in solar energy systems with storage battery assistance. There is a corresponding growing interest in hybrid converters. This paper provides a comprehensive review of hybrid converter topologies. The concept of a hybrid inverter is introduced and then classified into isolated and non-isolated structures based on using a galvanic transformer. The classification and description of each type are presented based on the features and applications. Furthermore, the most popular commercial solutions are investigated in terms of their simplicity, flexibility, efficiency, and battery technology. The summarizing features are presented through tables, and future trends for researchers to follow to develop efficient hybrid converters are discussed. This review paper is intended as a convenient reference for hybrid converter users.

This article studies the model predictive control (MPC) for a twisted buck–boost inverter based on unfolding circuit. The focus is on the practical implementation of the MPC algorithm for the microcontroller designed for application in power electronics. Selection of proper cost function parameters along with a continuous control set reduced prediction horizon, at the same time keeping good quality of the grid current. The results showed that simplified differential equations and a multicore microcontroller contribute to the sample time reduction, which in turn increases the sampling frequency with the corresponding increase in the output current quality. The simulation and experimental results confirmed theoretical predictions. In conclusion, the MPC technique suits for reducing zero-crossing distortion and in applications based on unfolding circuit.