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Abstract A new DC–DC buck–boost converter with a wide conversion ratio is presented in this paper. The proposed buck–boost converter consists of a combination of modified boost converter and ZETA converter, which has the advantages of both converters such as continuous input/output current and positive polarity of the output voltage. The combination of these two converters achieves semi-quadratic voltage gain and makes the proposed converter suitable for industrial and renewable energy applications. With a voltage gain higher than that of the ZETA converter and modified boost converter, the proposed converter also reduces input current stress due to its continuity. Two operating states are available for this converter in continuous conduction mode. This converter has two switches that operate simultaneously and can be easily controlled. The converter's output voltage ripple and output capacitor current stress are reduced as a result of continuous output current. Computational analysis and the introduced structure efficiency considering the influence of parasitic elements are presented in this paper. The small signal modelling and closed-loop control, as well as simulation and experimental results are also presented. This converter has also been compared with other similar and recently presented topologies. Finally, a 40–60 W, 20–76 V for boost mode and 10 V for buck mode prototype was implemented to verify the accuracy of the computational analysis.

The DC circuit breaker (DCCB) is a critical device that ensures the safe and reliable operation of the DC transmission system. As the level of DC voltage and transmission power increases, the flexible DC grid will need more and more opening capacity of the DCCB, as well as the burden of high costs. To solve the problem of excessive voltage and current stresses in existing DCCBs during DC fault current opening, an Improved Hybrid DCCB with the capacity of current-limiting and voltage-limiting is proposed, which crucially adds current-limiting and voltage-limiting branches. The current limiting branch can be activated 2 ms earlier in a fault circuit, significantly reducing the number of diodes and IGBTs required for branch transfer. In addition, overvoltage problems can be greatly reduced by properly designing the parameters of the current limiting branch. These improvements significantly increase the open ability, safety, reliability, and economy of the DCCB. The improved hybrid DCCB is shown to be effective and feasible by a large number of simulation and experimental test results.

In this paper, based on the pseudo-totem pole (PTP) circuit, a family of five-level PTP dual boost converters (PDBC) is proposed. A dual boost converter has some unique advantages, such as having no risk of bridge arm shoot-through and no problems related to switch body diode reverse recovery; thus, it has a good potential for applications. First, the derivation process, working principle, modulation and strategy of the topology are analyzed. Further, the number of power devices, switch voltages and current stress of the proposed topology is analyzed. Finally, a representative five-level PDBC experimental prototype is designed with AC input 220 V/50 Hz, DC output 400 V/1 kW, and peak efficiency of 98.27%. The experimental results show that the five-level PDBC proposed in this paper has higher efficiency and the correctness of its topology is verified. [ABSTRACT FROM AUTHOR]

In this Paper, a Dual Input buck - boost DC-DC (DIDC) converter is introduced for the integration of two input energy sources. The converter is capable of integrating energy sources which have different V-I characteristics. The output equation of the DIDC converter is derived from different working states using voltage - second principle. The voltage and current stress analysis of the converter are also carried out. The detailed study of the converter is conducted in the MATLAB/Simulink platform and the results are validated through laboratory experiments. [ABSTRACT FROM AUTHOR]

Summary: This paper proposes a new nonisolated multiport DC‐DC converter with two inputs and two outputs with different voltage levels. Different energy sources with distinct voltage‐current characteristics can be utilized as the input sources. Regarding multiple outputs, the proposed converter can be utilized in electric vehicles (EVs) to supply the DC traction motor and the auxiliary loads. The main advantages of the proposed converter include the high voltage gain with small values of the duty cycles, low normalized peak voltage stress (NPVS) across the semiconductors, and the continuous input currents. The voltage stress across the semiconductors is lower than the maximum output voltage. This feature makes it possible to use the switches with low turn‐on resistance and the diodes with reduced rating voltage. Performance principals of the proposed converter along with the steady‐state analysis, such as the derivation of the voltage gains, voltage and current stresses of the semiconductors, etc, are carried out. Experimental measurements made for the laboratory prototype of the proposed converter confirm the theoretical analysis. [ABSTRACT FROM AUTHOR]

This paper presents a novel three-phase current source rectifier (CSR) for AC/DC step-down voltage conversion to reduce voltage and current stress. The proposed converter features an asymmetrical connection between upper and lower arms compared with conventional CSRs, but has the same number of devices. With the proposed asymmetrical structure and modified space vector pulse width modulation (SVPWM) scheme, half of transistors only need to withstand half of the line-to-line voltage rather than the full line-to-line voltage, and its DC link current can be shared by multiple switches in freewheeling periods. Therefore, it is able to bring about a significant reduction in voltage and current stress, allowing for an improvement in the converter without additional cost. The topological structure, operation principles, and comparative analysis are specifically presented. Finally, an experimental prototype is built up to verify the performance of the proposed converter.

This paper presents a novel three-phase current source rectifier (CSR) for AC/DC step-down voltage conversion to reduce voltage and current stress. The proposed converter features an asymmetrical connection between upper and lower arms compared with conventional CSRs, but has the same number of devices. With the proposed asymmetrical structure and modified space vector pulse width modulation (SVPWM) scheme, half of transistors only need to withstand half of the line-to-line voltage rather than the full line-to-line voltage, and its DC link current can be shared by multiple switches in freewheeling periods. Therefore, it is able to bring about a significant reduction in voltage and current stress, allowing for an improvement in the converter without additional cost. The topological structure, operation principles, and comparative analysis are specifically presented. Finally, an experimental prototype is built up to verify the performance of the proposed converter. [ABSTRACT FROM AUTHOR]