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This paper presents the design of a disturbance observer-based controller that regulates the output voltage of three-phase four-leg voltage source inverters (VSIs) deployed for grid-forming operation in Renewable Energy-based Distributed Generation (REDG) Systems. The primary objective of the controller is to provide a symmetric and sinusoidal voltage at the output of the VSI when supplying highly unbalanced and nonlinear loads. The controller employs the feedback linearization (FL) technique and incorporates a disturbance observer (DO) to address a range of disturbances that include oscillations resulting from unbalanced loads, harmonics generated by nonlinear loads, and non-oscillatory disturbances. Notably, the controller adopts a direct control scheme without the need for nested current control loops and does not use any transformation frames. Simulation studies and experimental investigations were conducted to assess the controller's performance under various load conditions, including both linear and nonlinear types, as well as load transients. The findings demonstrate the controller's capability to accurately track references while complying with the IEEE power quality standards for the tested conditions. [ABSTRACT FROM AUTHOR]

This paper recommends new design for non-isolated semi-quadratic buck/boost converter with two similar structure that includes the following features: (a) the continuous input current has made it reasonable for PV solar applications and reduced the value of the capacitors in the input filter reducing the input ripple as well as EMI problems; (b) the topology is simple, and consists of a few numbers of components; (c) the semiconductor-based components have lower current/voltage stresses in comparison with the recently recommended designs; (d) semi-quadratic voltage gain is D (2 − D) / (1 − D)2; (e) 94.6 percent from the theoretical relations and 91.8 percent from the experimental for the output power of 72W, the duty of 54.2 percent, and output voltage of 72 V are the efficiency values in boost mode; (f) 89.3 percent from the theoretical relations and 87.2 percent from the experimental for the output power of 15W, the duty of 25.8 percent, and output voltage of 15 V are the efficiency values in buck mode. One structure is the continuous output current and negative output polarity, and other structure is positive output polarity. The recommended topologies have been studied in both ideal and non-ideal modes. The continuous current mode (CCM) is the suggested mode for the proposed converters. Moreover, the requirements of CCM have been discussed. The various kinds of comparisons have been held for voltage gain, efficiency, and structural details, and the advantages of the suggested design have been presented. A small-signal analysis has been completed, and the suitable compensator has been planned. Finally, PLECS simulation results have been associated with the design considerations. [ABSTRACT FROM AUTHOR]

In this work, a transformerless DC/DC converter is presented with dual operating modes buck–boost procedure. As a simple structure and continuous input current port, the system acts as a common ground between the output and input terminal. One operating mode, quadratic voltage gain ratio is D/(1‐D)2, and other mode is D/(1‐D). In the present study, the continuous conduction mode (CCM), steady‐state conditions were assumed to analyze efficiency and small‐signal modeling by replacing parasitic resistance effects. The findings revealed that in comparison with other buck‐boost converters, the two voltage gain ratios were provided with fewer components and lower total switching device power in dual operating modes. Therefore, proposed converter can attract considerable attention for renewable energy applications, especially photovoltaic systems. Ultimately, the experimental findings of a prototype made in the laboratory are provided along with the received waveforms from the simulation in PLECS for validation purposes. [ABSTRACT FROM AUTHOR]

In this paper, a positive output DC/DC converter with low total switching device power in dual working modes is introduced. One working mode is a step-up mode (boost), and other is a step-up/down mode (buck-boost). The proposed converter in step-up mode has high voltage gain ratio, low stress on switches, and continuous input current. In other working mode, the buck-boost converter with six relevant DC/DC converters is compared. By this comparison, it can be seen that the proposed converter has a lower voltage gain ratio, but instead the converter characteristics such as voltage stress on power switches and charge pump capacitors are in good condition for this mode. The proposed converter is analyzed in terms of the continuous conduction mode (CCM), steady state and efficiency with replacement of parasitic resistance effects. To validate the performance of the proposed converter experiments are conducted in the laboratory to claim the theoretical waveforms obtained from the PLECS simulation. [ABSTRACT FROM AUTHOR]