Boost converters and multilevel inverters (MLI) are frequently included in low-voltage solar photovoltaic (PV) systems for grid integration. However, the use of an inductor-based boost converter makes the system bulky and increases control complexity. Therefore, the switched-capacitor-based MLI emerges as an efficient DC/AC voltage convertor with boosting capability. To make classical topologies more efficient and cost-effective for sustainable power generation, newer topologies and control techniques are continually evolving. This paper proposes a reduced-component-count five-level inverter design for generating stable AC voltages for sustainable grid-integrated solar photovoltaic applications. The proposed topology uses seven switching devices of lower total standing voltage (TSV), three diodes, and two DC-link capacitors to generate five-level outputs. By charging and discharging cycles, the DC capacitor voltages are automatically balanced. Thus, no additional sensors or control circuitry is required. It has inherent voltage-boosting capability without any input boost converter. A low-frequency-based half-height (HH) modulation technique is employed in the standalone system for better voltage quality. Extensive simulations are performed in a MATLAB/Simulink environment to estimate the performance of the proposed topology, and 17.58% THDs are obtained in the phase voltages. Using a small inductor in series or an inductive load, the current THD reduces to 8.23%. Better dynamic performance is also observed with different loading conditions. A miniature five-level single-phase laboratory prototype is developed to verify the accuracy of the simulation results and the viability of the proposed topology.

This paper presents a comparative analysis of the zero-voltage zero-current switching (ZVZCS) soft switching technique with zero-voltage switching (ZVS) and zero-current switching (ZCS) counterparts. The generalization of the voltage–current crossover or the energy loss factor obtained from simulation of the prototype converter shows that the ZVZCS significantly reduces the losses and helps to improve the efficiency of the converter as compared to the ZVS or the ZCS. On the other hand, it is also found that the soft switching range of operation of the ZVS and the ZCS is largely affected by the maximum switch voltage and switch current, respectively. In contrast, these factors have a negligible effect on the ZVZCS operation which results in an extended range of soft switching operation. Additionally, a detailed PSPICE simulation is performed for selected ZVS, ZCS, and ZVZCS topologies from the recent literature, and the switching losses in the main switches of the converters are measured. It is observed that the energy losses in the ZVZCS mode are reduced on average by approximately 26% at turn on and 20% at turn off as compared to the ZVS and the ZCS. Furthermore, the low standard deviation in this mode confirms a stable low-loss profile which renders an extended soft switching range. An experimental test is also conducted by building the prototype converter to verify the simulation results. It is found that the switching losses are minimum while the converter is operated in the ZVZCS mode. Additionally, the efficiency drop remains consistently low as compared to the ZVS and the ZCS in the whole operating range. Accordingly, the simulation and the experimental results are both found to be consistent.

Despite the vast potential of wind energy, it has yet to be implemented widely in Bangladesh. Several barriers play major roles in obstructing the wind energy sector’s development in Bangladesh. Hence, it is necessary to identify these barriers to progress this sector’s growth. The analytic hierarchy process (AHP) is a multi-criteria decision-making method that can rank alternatives by considering multiple factors. It is a valuable tool for complex decision-making problems with multiple criteria, and their relationships must be clarified. So, in this analysis, AHP is used to rank the barriers related to wind energy development in Bangladesh. First, six main barriers and eighteen sub-barriers have been identified from a detailed and comprehensive literature review. The main barriers are categorized into technical, administrative, policy and political, economic, social, and geographic. After that, a questionnaire was sent to experts to obtain their opinions on these barriers. Based on the analysis, it was found that, with a weighted score of 0.46, technical barriers were the most significant ones. Administrative barriers ranked second with a weighted score of 0.21, and social barriers ranked last with a weighted score of 0.03. Among the sub-barriers, risks associated with technology were found to be the most significant, while land use conflict was found to be the least significant. Finally, several recommendations are provided to overcome the wind energy barriers in Bangladesh. The findings of this study can help policymakers and stakeholders develop strategies to overcome the barriers to wind energy development in Bangladesh.

To date, the grid-connected solar photovoltaic (PV) system has drawn consideration from researchers and academicians due to the speedy improvement and the declining price of solar panels. The proficiency and dependability of a grid integrated PV system rest mainly on the power conversion unit and the proper controlling mechanism. This paper introduces a novel asymmetric hexagonal-shaped fifteen-level inverter designed to feed a grid-integrated solar PV system. First, it aims to reduce the number of components and thereby decrease the installation space and cost of the multilevel inverter. Moreover, it has a low total blocking voltage (TBV) and total device rating (TDR) and uses few switching devices for generating per level of output voltage. The proposed topology utilizes only eight switching devices for generating fifteen levels at the output, which is lower than conventional multilevel inverter topologies. Here, a low-frequency modulation scheme using the half-height (HH) method generates switching pulses to minimize the complexity. The proposed multilevel inverter topology is also validated through the simulations in the MATLAB SIMULINK environment. The proposed inverter need for filters is illustrated according to different grid codes for integrating PV systems to the grid.

In variable speed applications, the cycloconverter-based AC to AC power conversion technique has gained more attention among researchers and academics than the traditional rectifier-inverter-based AC to AC power conversion process. The conventional rectifier-inverter-based AC to AC power conversion process has several disadvantages. It uses multi-power stages that increase the converter power conversion losses and increase the cost, volume, and weight of power losses. Besides high conduction and switching losses, the electromagnetic interference problems also accompany the above issues. In this regard, this paper proposes a novel step-down Triac based cycloconverter for variable speed control applications. The proposed topology uses only five Triac devices for one-third and one-fourth frequency conversion of 50 Hz with reduced total harmonics distortion without using any pulse width modulation techniques. The proposed model is designed in the MATLAB/SIMULINK environment. The simulation results show that around 18.85% and 23.67% of total harmonics distortions are reduced in the proposed converter for one-third and one-fourth frequency conversion of 50 Hz, respectively. Two physical experiments are carried out to prove the validity of the simulation results.