• Proceedings of the KIPE Conference
• /
• 1999.07a
• /
• pp.643-645
• /
• 1999

The conventional high frequency phase-shifted full bridge dc/dc converter has a disadvantage that a circulating current flows through transformer and switching devices during the freewheeling interval. Due to this circulating current, RMS current stress, conduction losses of transformer and switching devices are increased. To alleviate this problem, this paper provides a circulating current free type high frequency soft switching phase-shifted full bridge (FB) dc/dc converter with the modified energy recovery snubber (ERS) attached at the secondary side of transforemr.

• The Transactions of the Korean Institute of Electrical Engineers
• /
• v.37 no.8
• /
• pp.534-539
• /
• 1988

The dynamic chatacteristics and stability including steady state characteristic of the currentfed DC-to-DC converter with multiouput, which has a considerable advantage about the multioutut circuit,are analyzed in this paper. It is performed by using the steady state averaging method. As result, we know that the error, which is caused by secondary winding resistance of the transformer, exists between the two outputs in the steady state characteristics. Furthemore, it is verified that the current-fed DC-to-DC converter has also excellent stability in the multioutput application.

• Proceedings of the KIEE Conference
• /
• 1999.07f
• /
• pp.2512-2514
• /
• 1999

A new zero voltage and zero current switching(ZVZCS) full bridge DC-DC converter with transformer isolation is proposed for arc welding machines. The proposed DC-DC converter uses an auxiliary transformer to obtain ZCS for leading leg, which provides load current control capability even in short circuit condition. The auxiliary circuit also operates in ZVZCS mode. The power rating of the auxiliary transformer is about 10% of the main transformer. The operation is verified by experiments for 12[KW] prototype.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2010.11a
• /
• pp.583-584
• /
• 2010

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.19 no.1
• /
• pp.109-116
• /
• 2005

Wind power and photovoltaic(PV) systems are getting into the spotlight as substitute energy. But problem is happened stability by speed change of wind and the power output of the sun's ray. The power output amount according to velocity of wind power system. System breakdown can happen at change of sudden velocity, typhoon and night. This paper shows a automatic tail safety brake controller based on feedback control using wind velocity. The operation of automatic tail safety controller verified by manual test. PV system is a energy change system by temperature of sun's ray and cell. Maximum power point tracking(MPPT) is used in PV systems to maximize the photovoltaic array output power. In existed PV system is low output and changeable DC voltage for boost and filtering the buck-boost converter use. But, this paper established deformed DC-DC converter. Changed Buck-boost converter's unlined output current to line output current using DC-DC converter. This is effect that reduce ripple of output current. Proved through an output waveform comparison experiment. Finally, tail safety brake controller is established to wind turbine system for stability elevation and DC-DC converter is established on PV system for stability output.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2012.10a
• /
• pp.247-250
• /
• 2012

This paper describes a DC-DC Boost converter for Thermoelectric Energy Harvesting. The designed converter boosts the $V_{DD}$ through a start-up block from a low output voltage of thermoelectric devices and the boosted $V_{DD}$ is used to operate the internal block circuits. When $V_{DD}$ reaches a predefined value, a detector circuit makes the start-up block turn off for minimizing current consumption. The final boosted $V_{OUT}$ is achieved by alternately operating the DC-DC converter for $V_{DD}$ and the other converter for final output $V_{OUT}$ according to the comparator output. Simulation results shows that the designed converter outputs 2.8V from an input voltage of 200mV. The area of the chip designed using a 0.35um CMOS process is $1.52mm{\times}0.95mm$ including pads.

• Journal of IKEEE
• /
• v.18 no.2
• /
• pp.220-227
• /
• 2014

This paper presents a control method of Single-Inductor Dual-Output DC-DC Converter using Common mode feedback and differential feedback loops. To generate duty used for differential mode feedback loop, this paper propose relative sawtooth circuit using current divider circuit which makes ramp signal with variable dead-time. Two outputs of the Single-Inductor Dual-Output DC-DC Converter are specified for 2.8 V and 4.2 V with input voltage 2.5 V. The maximum conversion efficiency of designed SIDO DC-DC Converter is 95% at total output power of 539mW. Cross regulations of Boost1 and Boost2 are 3.57% and 4% each, when increasing twice times output current.

• Journal of Power Electronics
• /
• v.5 no.2
• /
• pp.99-103
• /
• 2005

In this paper, a novel circuit topology of a three-winding coupling inductor-assisting a high-frequency PWM boost chopper type DC-DC power converter with a high boost voltage conversion ratio and low switch voltage stress is proposed for the new energy interfaced DC power conditioner in solar photovoltaic and fuel cell generation systems. The operating principle in a steady state is described by using its equivalent circuits under the practical condition of energy processing of a lossless capacitive snubber. The newly-proposed power MOSFET boost chopper type DC-DC power converter with the three-winding coupled inductor type transformer and a single lossless capacitor snubber is built and tested for an output power of 500W. Utilizing the lower voltage and internal resistance power MOSFET switch in the proposed PWM boost chopper type DC-DC power converter can reduce the conduction losses of the active power switch compared to the conventional model. Therefore, the total actual power conversion efficiency under a condition of the nominal rated output power is estimated to be 81.1 ％, which is 3.7％ higher than the conventional PWM boost chopper DC power conversion circuit topology.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.12 no.5
• /
• pp.394-399
• /
• 2007

In this paper, we study on a novel Buck-Boost converter of high efficiency by soft switching method. The proposed Buck-Boost converter is applied to new soft switching method in restraint of increment of switching power loss in the conventional Buck-Boost converter. The soft switching circuit is designed to modification of a energy storage inductor and a snubber circuit used by the conventional converter, and then the proposed converter is simplified. The controlling switches of the proposed converter is operated with soft switching by a partial resonance behavior. The output voltage of the converter is regulated by PWM control technique. The discontinuous mode action of current flowing into inductor makes to simplify control method and control components. The proposed Buck-Boost converter is compared with the conventional converter. Some computer simulative results and experimental results are confirmed to the validity of the analytical results.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.22 no.4
• /
• pp.312-323
• /
• 2017

This paper introduces the bidirectional dc-dc converter design case study, which employs silicon-carbide (SiC) MOSFETs for battery energy storage system (BESS). This converter topology is selected as bidirectional synchronous buck converter, which is composed of a half bridge converter, an inductor, and a capacitor, where the converter has less conduction loss than that of a unidirectional buck and boost converter, and to improve the converter efficiency, both the power stage design and power conversion architecture are described in detail. The conduction and switching losses are compared among three different SiC devices in this paper. In addition, the thermal analysis using Maxwell software of each switching device supports the loss analyses, in which both the 2 kW prototype analyses and experimental results show very good agreement.