• 전력전자학회논문지
• /
• 제19권6호
• /
• pp.481-487
• /
• 2014

This study proposes a two-phase non-inverting buck-boost converter that uses a coupled inductor. The multi-phase converter has many advantages over single-phase counterparts, such as reduced output current ripple and conduction loss in switching devices and passive elements. Although the output current ripple of the multi-phase converter is reduced significantly because of the interleaved effect, the inductor current ripple is not reduced in multi-phase converters. One of the solutions to this problem is to use a coupled inductor. A 4 kW prototype converter is built and tested to verify the performance of the proposed converter.

• Journal of information and communication convergence engineering
• /
• 제14권2호
• /
• pp.122-128
• /
• 2016

In the future, hybrid power management systems using fuel cells (FCs) and batteries will be used as the driving power systems of ships. These systems consist of an FC, a converter, an inverter, and a battery. In general, an FC provides steady-state energy; a battery provides the dynamic energy in the start state of a ship for enabling a smooth operation, and provides or absorbs the peak or dynamic power when the load varies and the FC cannot respond immediately. The FC voltage range is very wide and depends on the load; Therefore, the FC cannot directly connect to the inverter. In this paper, we propose a power management strategy and design process involving a unidirectional converter, a bidirectional converter, and an inverter, considering the ship's operating conditions and the power conditions of the FC and the battery. The presented experimental results were verified through a simulation.

• 에너지공학
• /
• 제28권1호
• /
• pp.65-72
• /
• 2019

한국정부는 재생에너지를 이용한 발전량 비중을 2030년까지 총 발전량의 20%까지 높이겠다는 목표를 제시하였다. 풍부한 해양 신재생에너지 자원은 한국정부가 이 목표를 달성하는데 중요한 역할을 할 수 있을 것이다. 이 논문은 1.0 m/s의 낮은 유속에서도 높은 효율을 달성할 수 있는 유동유발진동 현상을 이용한 조류에너지 발전기술을 소개하고 한국 7개 해안의 평균유속을 바탕으로 높은 효율을 달성할 수 있는 유동유발진동 발전기의 최적 설계를 제안하고자 한다. 또한, 이를 바탕으로 각 해안에서 발전할 수 있는 이론적 잠재량을 산정하고자 한다. 유동유발 발전기술을 이용한 연간 이론적 최대발전량은 221.77 TWh로 예측되었고 이는 2013년 한국의 총 전력소비량의 42.3%에 해당한다. 본 연구결과는 유동유발진동을 이용한 발전기술을 이용한 조류발전기술이 한국 정부가 제시한 목표를 달성하는데 중요한 역할을 할 수 있음을 보여준다.

• 한국해양공학회지
• /
• 제30권1호
• /
• pp.1-9
• /
• 2016

In order to convert wave energy into large quantities of high-efficiency power, it is necessary to study the optimal converter system appropriate for the environment of a specific open ocean area. A wave energy converter system with a counterweight converts the translation energy induced from the heave motion of a buoy into rotary energy. This experimental study evaluated the primary energy conversion efficiency of the system, which was installed on an ocean generating basin with a power take-off system. Moreover, this study analyzed the energy conversion performance according to the weight condition of the buoy, counter-weight, and flywheel by changing the load torque and wave period. Therefore, these results could be useful as basic data such as for the optimal design of a wave energy converter with a counterweight and improved energy conversion efficiency.

• Journal of information and communication convergence engineering
• /
• 제15권1호
• /
• pp.62-71
• /
• 2017

This paper presents a low-power voltage converter based on a reconfigurable capacitor array. Its energy recycling capacitor array stores the energy during a charge stage and supplies the voltage during an energy recycle stage even after the power source is disconnected. The converter reconfigures the capacitor array step-wise to boost the lost voltage level during the energy recycle stage. Its energy saving is particularly effective when most of the energy remaining in the charge capacitors is wasted by the leakage current during a longer sleep period. Simulations have been conducted using a voltage source of 500 mV to supply a $V_{DD}$ of around 800 mV to a load circuit consisting of four 32-bit adders in a 65-nm CMOS process. Results demonstrate energy recycling efficiency of 85.86% and overall energy saving of 40.14% compared to a conventional converter, when the load circuit is shortly active followed by a long sleep period.

• 수산해양교육연구
• /
• 제27권5호
• /
• pp.1303-1309
• /
• 2015

The behavior and flow characteristics of the floating wave energy converter were analyzed by using CFD in this study. The average significant wave height was confirmed as 0.5~2.0m from the Korean coastal sea area. This study was carried out by selecting a range of 1.0~1.6m in the wave height to simulate the operations of realistic wave energy converter system. The principle of a piston wave maker was applied in order to produce periodic wave. The behavior of the wave energy converter and the state of the wave overtopping according to the generated periodic wave were confirmed through the unsteady three-dimensional flow analysis. It was found that the wave overtopping rate according to the generated periodic wave was in range of the 11.6~30.0 kg/s.

• 한국조명전기설비학회:학술대회논문집
• /
• 한국조명전기설비학회 2005년도 학술대회 논문집
• /
• pp.251-255
• /
• 2005

This paper proposes a new soft switching technique for a phase-shift controlled bi-directional DC-DC converter. The described converter employs a low profile high frequency transformer and two active full-bridge converters for bidirectional power flow capability. A new soft switching technique is proposed, which guarantees soft switching over wide range (no load to full load) without any additional circuit components. In the proposed switching scheme, the switch pairs in the diagonal position of the converter each are turned on/off simultaneously by the switching signals with a variable duty ratio depending on the phase shift amount, and the converter is operated without freewheeling interval.

• 전력전자학회논문지
• /
• 제23권5호
• /
• pp.352-358
• /
• 2018

A split-capacitor (SC) dual-active-bridge (DAB) converter is proposed in this study. The DC-link capacitors of input and output are split in the proposed converter. The primary and secondary windings of transformer are connected to the midpoints of the DC-links. Hence, the SC DAB converter can inherently prevent transformer from saturation. Although the switch current stress of the proposed converter is twice that of the conventional DAB converter, the switch voltage stress is reduced by half. Therefore, the proposed converter can reduce switching loss and achieve high efficiency in a high switching frequency. Given the SC structure, the proposed converter can readily be connected to neutral-point-clamped- or half-bridge-type converters. The topology of the proposed converter is presented and the operating principle is analyzed in detail. A 3-kW hardware prototype was built and tested to verify the performance of the proposed converter.

• International journal of advanced smart convergence
• /
• 제9권3호
• /
• pp.9-16
• /
• 2020

In this paper, we designed a soft switched synchronous boost converter, which can perform discharging the battery, is simulated, and experimented designed. The converter operates synchronous operation to increase efficiency of the converter. The converter has very small switching losses because of its soft switching characteristics. In this paper, battery discharger with a switching frequency of 100 kHz have been designed. The designed converter also simulated and experimented to prove the converter's characteristics during synchronous operation. The simulated and experimental results have confirmed that the battery discharger had soft switching characteristics. In addition, the experimental results confirm that the converter has high efficiency characteristics. The efficiency of the circuit exceeds 97%, the efficiency of soft switched synchronous boost converter is at least 6% higher than that of conventional PWM boost converter.

• 전력전자학회논문지
• /
• 제22권1호
• /
• pp.36-43
• /
• 2017

This paper describes a hybrid multi-output three-level DC/DC converter suitable for a wide, high-input voltage range of an auxiliary power supply for a high-power photovoltaic generating system. In a high-power photovoltaic generating system, the solar panel output voltage depends on solar radiation quantity and varies from 450Vdc to 1100Vdc. The proposed hybrid multi-output three-level DC/DC converter, which is an auxiliary power supply, would be used as power source for control printed circuit boards and relay and cooling fans in a high-power photovoltaic generating system. The proposed multi-output ($24V_{DC}/30A$, $230V_{DC}/5A$) hybrid three-level boost converter, which uses an energy recovery snubber, is controlled by variable-frequency and phase-shifted modulations and can achieve zero-voltage switching with all operating conditions of input voltage and load range. Experimental results of a 2kW prototype are evaluated and implemented to verify the performance of the proposed converter.