• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.920-921
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• 2008

This paper presents the efficiency analysis of CCM(Continuous Current Mode) boost converter. A thorough efficiency analysis of a boost converter taking into account the conduction losses, the diode power loss, the switching losses, the gate-drive loss and the capacitive switching loss, for both continuous conduction mode is presented.

• Proceedings of the KIEE Conference
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• 2003.04a
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• pp.276-280
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• 2003

This paper presents a zero voltage and zero current switching (ZVZCS) interleaving two-transistor forward converter for high input voltage and high power application. A phase shift has a disadvantage that a circulating current and RMS current stress, conduction losses of transformer and switching devices increases. Due to this circulating current and RMS current stress, conduction losses of transformer and switching devices increases. To alleviate these problems, we propose an improved interleaving two-transistor forward Zero Voltage and Zero Current Switching (ZVZCS) dc/dc converter using a tapped inductor a snubber capacitor and two snubber diodes attached at the secondary side of transformer. The proposed ZVZCS converter is verified on a 1.8kW, 5kHz experimental prototype.

• Proceedings of the KIPE Conference
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• 2019.11a
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• pp.124-125
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• 2019

This paper proposes a novel control method to minimize conduction losses of dual active bridge (DAB) converters for on-board chargers of electric vehicles (EVs). In the control method, two variables are regulated, which are the phase-shift angle between the primary and secondary full bridges and the switching frequency. From time-domain analysis, an optimal phase-shift angle is derived to achieve the minimum RMS value of the transformer current. The proposed method was implemented for a 3.6-kW SiC-based prototype to validate its effectiveness. A high efficiency over 97.3% has been achieved for a wide output voltage range.

• Proceedings of the KIPE Conference
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• 2001.07a
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• pp.520-524
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• 2001

Recently, the demand of large capacity SMPS for industrial area is increasing. Full-bridge dc-dc converter with IGBT is most widely used for large capacity SMPS because IGBT has a low-conduction loss and large current capacity, But most large capacity Full-bridge do-dc converter using IGBT has low operating frequency because of switching loss at IGBT especially at turn-off by current tail and it's cause of relatively big converter size. MOSFET has low switching losses has been widely used for high frequency SMPS but it has a problem to apply to large capacity SMPS because it has large conduction resistance causing large on-time losses. In this paper, for reduction losses at switching device, MOSFET is applied at parallel with IGBT in full-bridge dc/dc converter.

• The Transactions of the Korean Institute of Power Electronics
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• v.5 no.4
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• pp.386-393
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• 2000

This paper presents an improved ZVS partial series resonant DC/DC converter (PSRC) with low conduction losses, suitable for high power and high frequency applications. The proposed PSRC have advantages of zero-voltage-switching (ZVS) of main switches for entire load ranges low conduction losses of main switches by decreasing current stresses. Also the reduction of the effective duty cycle is not occurred during the resonant period of the main circuit because the auxiliary circuit of the proposed converter is placed out of the main power path. The auxiliary circuit is composed with passive components, which are an inductor, two capacitors, two diodes, and a saturable inductor. An improved ZVS PSRC has so much characteristics with respect to the overall system efficiency and to the reduction of current stresses. The operation principles of the proposed converter are explained in detail and the various simulated and experimental results show the validity of the proposed converter.

• Journal of Electrical Engineering and Technology
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• v.13 no.6
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• pp.2310-2318
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• 2018

Critical conduction mode (CRM) operation is more efficient than continuous conduction mode (CCM) operation at low power levels because of the valley switching of switches and elimination of the reverse recovery losses of boost diodes. When using a sensorless digital control method, an error occurs between the actual and the estimated current. Because of the error, it operates as CCM or discontinuous conduction mode (DCM) during CRM operation and also has an adverse effect on THD of input current. In this paper, a current sensorless technique is presented in an inverter system using a bridgeless boosted power factor correction converter, and a compensation method is proposed to reduce CRM calculation error. The validity of the proposed method is verified by simulation and experiment.

• Proceedings of the KIEE Conference
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• 1999.07f
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• pp.2568-2571
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• 1999

Recently, new trend in telecommunication device is to apply low voltage, about 3.3V-1.5V. However, it is undesirable in view of high efficiency and power desity which is the most important requirement in the distributed power system. Rectification loss in the output stage in on-board converter for distributed power system are constrained to obtain high efficience at low output voltage power suppies. This paper is investigated conduction power loss in synchronouss rectifier with a parallel -connected Schottky Barrier Diode(SBD). Conduction losses are calculated for both MOSFET and SBD respectively. The SBD conduction power loss dissipates more than the MOSFET rectifier conduction power loss.

• Journal of Power Electronics
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• v.7 no.1
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• pp.55-63
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• 2007

This paper proposes a simple unity power factor zero-voltage-transition (ZVT) pulse-width-modulated (PWM) single-phase rectifier, which features reduced switching and conduction losses. The switching loss reduction is achieved by a simple auxiliary commutation circuit, and the conduction loss reduction is achieved by employing a single-stage converter, rather than a typical double-stage converter comprising of a front-end rectifier and a boost rectifier. Furthermore, thanks to good features such as a simple PWM control at constant frequency, low switch stress, low Var rating of commutation circuits, and simple power circuit structure, it is suitable for high power applications. The principles of operation are explained in detail, and a major characteristics analysis and the experimental results of the new converter are also included in this paper.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 1999.11a
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• pp.157-161
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• 1999

This paper presents a Single-phase Semi-Bridge PWM Converter, which features Continuos Conduction Mode and Phase-adjusted Unipolar PWM Method. The reduced conduction losses are achieved by the employment of a single converter, instead of the typical configuration composed of a front end rectifier followed by a boost converter. Theoretical principle of operation, a design example and Simulation results of a 3kW Semi-Bridge PWM converter with 220 Vrms input voltage and 400 Vdc output voltage are presented.

• Proceedings of the KIPE Conference
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• 2001.07a
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• pp.698-701
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• 2001

Loss analyses of two soft switching techniques for two-transistor forward converters are presented. The sums of snubber conduction and capacitive turn-on losses for two transistors are calculated to compare the losses of two techniques. While the conventional soft switching technique shows the loss difference between two transistors, proposed soft switching technique shows equal as well as lower loss in two transistors.