• 전력전자학회논문지
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• 제17권6호
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• pp.523-531
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• 2012

This paper proposes a high efficiency power conversion system for battery-ultracapacitor hybrid energy storages. The proposed system has only one bidirectional dc-dc converter for hybrid power source with batteries and ultracapacitors. The hybrid power source has bidirectional switching circuits for selecting one energy storage device. Bidirectional power flow between the energy storage device and high voltage capacitor can be controlled by one bidirectional converter. An asymmetrical switching method is applied to the bidirectional converter for high power efficiency. Switching power losses are reduced by zero-voltage switching of power switches. System operation and design considerations are presented. The experimental results are provided to verify the performance of the proposed system.

• Journal of information and communication convergence engineering
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• 제5권4호
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• pp.358-361
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• 2007

We report on a new type dc-dc converter design that combines the advantage of dc ripple noise elimination and high efficiency. As potential low cost solar cells, DSC module and the panel's system efficiency and stability are still critical problems to the way of marketing. In this study, a new three-step dc-dc converter scheme with the phase-shift-carrier technology is proposed to apply for solar power system. We have achieved power conversion efficiency around 94.88%.

• 전자공학회논문지S
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• 제34S권6호
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• pp.77-84
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• 1997

buck type converter doesn't appear when an input voltag eis lower than an output voltage. This is the main reason the buck converter has not been used for high power factor converters. In this paper, soft switching high power factor buck converter is proposed. This converter is composed of diode rectifier, input capacitor can be small enough to filter input current, buck converter with loss less snubber circuit. Converter is operated in discontinous conduction mode, turn on of the switching device is a zero current switching (ZCS) and high powr factor input is obtianed. In addition, zero voltage switching (ZVS) at trun off is achieved and switching loss is reduced using loss less snubber circuit. The capacitor used in the snubber circuit raised output voltage. Therefore, proposed converter has higher output voltage and higher efficiency than conventional buck type converter at same duty factor in discontinous conduction mode operation. High power factro, efficiency, soft switching operation of proposed converter is veified by simulation using Pspice and experimental results.

• 한국정밀공학회지
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• 제32권5호
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• pp.455-461
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• 2015

This paper deals with an experimental verification of a temperature-dependent power loss model of a DC/DC converter in severe temperature conditions. The power loss of a DC/DC converter is obtained by summing the losses by the components constituting the converter including switching elements, diodes, inductors, and capacitors. MIL-STD-810F stipulates that any electronic devices must be operable in the temperature ranging from $-50^{\circ}C$ to $70^{\circ}C$. We summarized the temperature-dependent loss models for the converter components. A SEPIC-type converter is designed and built as a target. Using a constant-temperature chamber, a test rig is set up to measure the power loss of the converter. The experimental results confirm the validity of the loss model within 4.5% error. The model can be useful to predict the efficiency of the converter at the operating temperature, and to provide guidelines in order to improve the efficiency.

• Journal of Power Electronics
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• 제6권2호
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• pp.121-130
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• 2006

This paper presents the performance and efficiency of a drive system incorporating a switched-reluctance motor (SRM) with input power factor correction (PFC). The proposed system consists of a PFC, bi-directional converter, an inverter, and a SRM operating as based voltage source drives (VSD). First, theoretical analysis is made for each identified mode of operation in the drive system. This is followed by comparing the performance of the SRM drive system with and without a PFC circuit. The losses are also calculated for both systems and overall efficiency. Experimental results are presented to prove the theoretical analysis.

• Journal of Power Electronics
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• 제19권5호
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• pp.1099-1107
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• 2019

A soft switching converter with wide voltage range operation is investigated in this paper. A series resonant converter is implemented to achieve a high circuit efficiency with soft switching characteristics on power switches and rectifier diodes. To improve the weakness of the narrow voltage range in LLC converters, an alternating current (ac) power switch is used on the primary side to select a half-bridge or full-bridge resonant circuit to implement 4:1 voltage range operation. On the secondary-side, another ac power switch is adopted to select a full-wave rectifier or voltage-doubler rectifier to achiever an additional 2:1 output voltage range. Therefore, the proposed resonant converter has the capacity for 8:1 (320V~40V) wide output voltage operation. A single-stage hybrid resonant converter is employed in the study circuit instead of a two-stage dc converter to achiever wide voltage range operation. As a result, the study converter has better converter efficiency. The theoretical analysis and circuit characteristics are verified by experiments with a prototype circuit.

• Journal of Power Electronics
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• 제3권4호
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• pp.249-258
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• 2003

This paper presents a high-efficient and cost effective three-phase AC/DC-DC/AC power conversion system with a single two-switch type active Auxiliary Resonant DC Link (ARDCL) snubber circuit, which can minimize the total power dissipation. The active ARDCL snubber circuit is proposed in this paper and its unique features are described. Its operation principle in steady-state is discussed for the three phase AC/DC-DC/AC converter, which is composed of PWM rectifier as power factor correction (PFC) converter, sinewave PWM inverter. In the presented power converter system not only three-phase AC/DC PWM rectifier but also three-phase DC/AC inverter can achieve the stable ZVS commutation for all the power semiconductor devices. It is proved that the proposed three-phase AC/DC-DC/AC converter system is more effective and acceptable than the previous from the cost viewpoint and high efficient consideration. In addition, the proposed two-switch type active auxiliary ARDCL snubber circuit can reduce the peak value of the resonant inductor injection current in order to maximize total system actual efficiency by using the improved DSP based control scheme. Moreover the proposed active auxiliary two-switch ARDCL snubber circuit has the merit so that there is no need to use any sensing devices to detect the voltage and current in the ARDCL sunbber circuit for realizing soft-switching operation. This three-phase AC/DC-DC/AC converter system developed for UPS can achieve the 1.8% higher efficiency and 20dB lower conduction noise than those of the conventional three-phase hard-switching PWM AC/DC-DC/AC converter system. It is proved that actual efficiency of the proposed three-phase AC/DC-DC/AC converter system operating under a condition of soft switching is 88.7% under 10kw output power.

• 산업기술연구
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• 제29권B호
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• pp.145-149
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• 2009

A RF-DC converter is one of the most important components for a wireless power transmission. It has been developed for many applications such as space solar power system, and Radio Frequency Identification(RFID). In this paper, we designed three types of RF-DC converter and compare the performance of each. All types RF-DC convertoer have a maximum conversion efficiency at input power level of 0 dBm~5 dBm and RF-DC converter of third type was the best performance that has a 21.9% of conversion efficiency.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 B
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• pp.1148-1150
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• 2003

Power conversion system must be increased switching frequency in order to achieve a small size, a light weight and a low noise. However, the switches of converter are subjected to high switching power losses and switching stresses. As a result of those, the power system brings on a low efficiency. To improved these, a large number of soft switching topologies included a resonant circuit has been prosed. But these circuits increase number of switch in circuit and complicate sequence of switching operation. In this paper, the authors propose a high power factor and high efficiency DC-DC converter using single-pulse soft switching by partial resonant switching node. The switching devices in a prosed circuit are operated with soft switching by the partial resonant method, that is, Partial Resonant Switch Mode Power Converter. The partial resonant circuit makes use of a inductor using step up and a condenser of loss-less snubber. The result is that the switching loss is very low and the efficiency of system is high. Also the proposed converter is deemed the most suitable for high power applications where the power switching devices are used. Some simulative results on computer results are included to confirm the validity of the analytical results.

• JSTS:Journal of Semiconductor Technology and Science
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• 제16권6호
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• pp.842-846
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• 2016

This paper presents a DC-DC buck converter which uses a sleep control to improve the power efficiency in a few mW light load condition. The sleep control turns off analog controller building blocks to reduce the static power losses during the off-duty period of pulse width modulation. For verification, a buck converter has been implemented in a $0.18{\mu}m$ CMOS process. The power efficiency has been improved from 76.7% to 82.5% with a 1.2 mW load. The maximum power efficiency is 95% with a 9 mW load.