• The Transactions of the Korean Institute of Power Electronics
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• v.25 no.2
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• pp.133-141
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• 2020

The use of high-gain-voltage step-up converters for distributed power generation systems is being popularized because of the need for new energy generation and power conversion technologies. In this study, a new constructed high-gain-boost DC-DC converter was proposed to coordinate low voltage output DC sources, such as PV or fuel cell systems, with high DC bus (380 V) lines. Compared with traditional boost DC-DC converters, the proposed converter can create higher gain and has wider input voltage range and lower voltage stress for power semiconductors and passive elements. Moreover, the proposed topology produces multilevel DC voltage output, which is the main advantage of the proposed topology. Steady-state analysis in continuous conduction mode of the proposed converter is discussed in detail. The practicability of the proposed DC-DC converter is presented by experimental results with a 300 W prototype converter.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.5
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• pp.88-95
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• 2009

This paper is the research on the development of power conversion system for the fuel cell. In composing the DC/DC converters which have high boost voltage ratio, unlike the conventional method a new multi DC/DC converter system is proposed that the diode and the condenser and the reactor can be reduced by connecting the secondary side output of the transformer. In this system the rectifier part and the filter part of the secondary side in the power transformer that is connecting in series are composed into a single module, which is the strong advantage and the number of level can be easily increased. A new variable shift phase switching method is also suggested that it makes possible to reduce the output voltage ripples in the proposed system. All the factors mentioned above have been verified through simulations and experiments, and the proposed converter is considered very useful in the demanded load which requires a wide of the output.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.10
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• pp.1655-1663
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• 2016

Recently the researches on Modular Multi-level Converter (MMC) are being highlighted because high quality and efficient power transmission are key issues in the High Voltage Direct Current (HVDC) transmission system. This paper proposes an improved pre-charging method for the sub-module capacitors in MMC that operates in Nearest Level Control (NLC) modulation. The proposed method does not require additional circuits or Pulse Width Modulation (PWM) techniques. The feasibility of proposed method was verified through computer simulations for a scaled 3-phase 10kVA MMC with 12 sub-modules per each arm. Hardware experiments with a scaled prototype were performed in the lab to confirm the simulation results.