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This paper proposes a non-isolated high step-up switched-capacitor dual-switch DC-DC converter for low-power applications. The proposed converter benefits from high voltage gain, low voltage stress on the devices, continuous input current, availability of common-ground point, and simple structure. The proposed converter provides the voltage gain of 10 at mild duty cycle of 50%, where the per-unit voltage stress of S 1 and S 2 switches are 20 and 40%, respectively. In such condition, the highest voltage stress on the diodes will be limited to 67%. The synchronous operation of the switches in proposed converter leads to only 2 operational modes in continuous conduction mode (CCM), which makes the control of the converter very straightforward. The interleaved structure divides the input current between the inductors, which accordingly reduces the losses on the input devices. This study contains detailed steady-state analysis of proposed converter in CCM and DCM operations. It also provides the loss (and efficiency) analysis as well as the design procedure of the devices. The comparison section evaluates the competitiveness of the proposed converter compared to other existing similar counterparts. The average state-space method and small signal analysis have been used to model the proposed topology. The appropriate dynamic operation of proposed converter has been verified by simulation analysis. The experimental results confirm the correct performance of the proposed converter.

A novel high-gain and high-efficiency direct current to direct current (DC-DC) converter is introduced in this paper. The presented converter is suitable for low-voltage renewable energy resources such as photovoltaic (PV) and fuel cell (FC). The existence of series inductance with the input source ensures continuous and low-ramp input current, which is important for extracting maximum power from resources. Using coupled inductor technology and an intermediate capacitor in the suggested converter leads to a high gain voltage. In the presented topology for recovering energy from the leakage inductor, reducing voltage stress on the power switch, and so decreasing overall converter losses, a passive clamp circuit is used. The suitable operation range of duty cycle in the converter, besides the leakage inductor, decreases the problem of reverse recovery in diodes. The low value of the leakage inductor and the low volume and cost of the proposed converter are due to the low turn ratio of the coupled inductor. Details of the operation principles of the proposed converter have been discussed in this paper. The presented simulation and laboratory prototype results verify the theoretical analysis and performance of the suggested topology.

Stand-alone/grid connected renewable energy systems (RESs) require direct current (DC)/DC converters with continuous-input continuous-output current capabilities as maximum power point tracking (MPPT) converters. The continuous-input current feature minimizes the extracted power ripples while the continuous-output current offers non-pulsating power to the storage batteries/DC-link. CUK, D1 and D2 DC/DC converters are highly competitive candidates for this task especially because they share similar low-component count and functionality. Although these converters are of high resemblance, their performance assessment has not been previously compared. In this paper, a detailed comparison between the previously mentioned converters is carried out as several aspects should be addressed, mainly the converter tracking efficiency, conversion efficiency, inductor loss, system modelling, transient and steady-state performance. First, average model and dynamic analysis of the three converters are derived. Then, D1 and D2 small signal analysis in voltage-fed-mode is originated and compared to that of CUK in order to address the nature of converters’ response to small system changes. Finally, the effect of converters’ inductance variation on their performance is studied using rigorous simulation and experimental implementation under varying operating conditions. The assessment finally revels that D1 converter achieves the best overall efficiency with minimal inductor value.

Impedance source converters as single-stage power conversion alternatives can boost and regulate the output voltages of renewable energy sources. Nevertheless, they, also known as Z-source inverters (ZSIs), still suffer from limited voltage gains and higher stresses across the components. To tackle such issues, extra diodes, passive components, and active switches can be utilized in the basic ZSIs. In this paper, a modified switched-quasi-Z-source inverter (S-qZSI) is proposed, which features continuous input currents and high boosting capability to boost output voltage by minor modifications of a prior-art topology. Furthermore, the voltage stress of the active switches is reduced, which contributes to a lower cost. The operation principles are discussed comprehensively. The performance of the proposed ZSI in terms of conversion ratio, voltage gain, and stresses on the power switches and capacitors is benchmarked with selected ZSIs. Finally, simulations and experimental tests substantiate the theoretical analysis and superior performance.

Impedance-source (Z-source) inverters are increasingly adopted in practice, where a high voltage gain is required. However, issues like drawing a non-continuous current from the DC source and ceasing the energy supply under DC source faults are also observed. In this paper, an embedded enhanced-boost Z-source inverter (EEB-ZSI) is thus proposed to tackle the issues. The proposed EEB-ZSI employs two DC sources, which enable the continuous input current and fault-tolerant operations (e.g., open-circuit and short-circuit faults in the DC sources). The operational principles are presented in detail with an in-depth circuit analysis. Moreover, the proposed EEB-ZSI is benchmarked with prior-art Z-source inverters. Experimental tests further demonstrate the effectiveness of EEB-ZSI regarding the continuous input current and flexible fault tolerance.

This paper proposes a family of high-efficiency DC-DC boost converters employing voltage-doubling coupled-inductor technology with a low component count. By varying the homonymous winding connections of the coupled inductor, three topologies are developed: parallel (PWCDVD-CLBC), series (SWCDVD-CLBC), and flipped-parallel (FPWCDVD-CLBC). These converters achieve high-voltage gain, continuous input current, and low-voltage stress across components. The PWCDVD-CLBC and FPWCDVD-CLBC configurations exhibit voltage gains proportional to the turn ratio, while the SWCDVD-CLBC shows an inverse relation, enabling reduced turn ratios. Detailed operational principles, mathematical analysis, and performance advantages are presented. A comparative evaluation demonstrates a higher voltage gain, realizes continuous input current, and has lower voltage stresses. The experimental results validate the theoretical analysis and confirm the feasibility and efficiency of the proposed designs.

This paper proposes an interleaved step-down converter (ISDC) with a capacitor-diode voltage splitter. Even though the ISDC only utilizes two active switches, it can significantly step down a high input voltage to a much lower level and achieve interleaved current at output and continuous current at input without using an extreme duty ratio. In addition, the ISDC is capable of sharing output current equally between two interleaved paths by controlling the two switches. Therefore, the ISDC has lower current ripples and reduces EMI noise. The ISDC can be easily expanded only by adopting capacitors and diodes for a much higher conversion ratio, avoiding using any active switch. A comprehensive analysis of ISDC is presented, including operation principle, steady-state analysis, design consideration, expendability of the power stage, and converter comparison. A prototype of 500 W is fulfilled to deal with 400-V input and 24-V output, which has verified the accuracy of the theoretical analysis and validated the converter. Experimental results demonstrate that the ISDC achieves a peak efficiency of 92.74% at 350 W and 92.09% at full load. If synchronous rectifiers are employed, the peak efficiency can be up to 94.73%.Article HighlightsPropose a high step-down converter to efficiently draw energy from high-voltage sources for low-voltage load. Furthermore, the converter is expandable to achieve a much lower output voltage.Ensure continuous input and output currents, thereby reducing EMI and volume.Achieve the feature of the common switch to bridge the front-end and downstream circuits to be cost-effective.

A wide-gain boost converter based on LCD cell is proposed in this study. The proposed topology is suitable for the fuel cells of electric vehicles that generate a specific bus voltage in power generation systems. It has none of the drawbacks of other reported LCD cell-based topologies, such as highly pulsating source current, lack of common ground, inverted load voltage polarity, and numerous switching devices. By integrating the classic boost converter with the LCD cell, the voltage gain is improved, and the features of single switch, low voltage and current stress, common ground, and continuous input current are satisfied simultaneously under the condition of using few components. Continuous input current is a desirable characteristic of DC–DC converters that is necessary for practical applications. After working principle and steady-state analyses, the salient features are compared in detail. Then, the performance of the converter and the correctness of the analysis are verified through the results of the experimental prototype.

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.

This paper focuses on introducing a transformerless DC/DC converter with low total switching device power in dual working modes including step-up and step-up/down modes. The proposed converter is analysed in terms of the continuous conduction mode, steady state, and efficiency with the replacement of parasitic resistance effects. The proposed converter in the step-up mode has a high voltage gain ratio and a continuous input current. Then, the other working mode of the proposed converter with relevant DC/DC converters is compared. By this comparison, the proposed converter has a high voltage gain ratio. Also, the converter characteristics such as voltage stress on power switches and charge pump capacitors are in a good condition in this mode. Finally, the experimental results from a laboratory made prototype and the obtained waveforms from the simulation in PLECS are presented for validation such as higher voltage gain ratio, lower total switching device power and better efficiency.