• The Transactions of the Korean Institute of Power Electronics
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• v.6 no.5
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• pp.453-459
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• 2001

In this paper, the loss analyses of two soft switching techniques for two-transistor forward converter are performed. The sums of snubber conduction and capacitive turn-on losses for two transistors are calculated to compare the losses of the two techniques. While the conventional soft switching technique shows the loss difference between two transistors, the proposed soft switching technique shows equal as well as lower losses In two transistors. Thus, it can be said that even thermal distribution and higher reliability can be obtained by the proposed soft switching technique.

• 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.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.1215-1217
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• 2000

For the application of soft-switching technique to single Phase-full bridge inverter. in this paper ZCT(Zero Current Transition) and ZVT(Zero Voltage Transition) techniques proposed previously are compared and discussed the merit and demerit of both. Both have a excellency that can reduce the number of auxiliary switch and resonant circuit compared to other techniques and achive soft-switching in auxiliary switch itself. Therefore, it has enabled us to have benifits of realizing high efficiency and reliability, low EMI for high switching frequency and reducing the cost as well as size of device.

• Journal of Power Electronics
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• v.2 no.3
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• pp.199-205
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• 2002

This paper compares three kinds of soft-switching circuits from viewpoints of surge suppression, load characteristic, and power efficiency for a tapped-inductor buck converter with low voltage and high current. As a result, these soft-switching techniques have achieved much higher efficiency of 80 % when compared with a hard-switching buck converter for the output condition of 1V and 20A.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.13 no.2
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• pp.220-220
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• 1999

This paper describes the high efficiency inverter ballast circuit using very cheap microprocessor, which has been developed by the author. A variety of soft-switching techniques have been proposed to reduce the switching losses and EMI problems that occur with higher switching frequencies in switched inverter ballast. The inverter ballast circuit, which employs a temperature sensing circuits has been also proposed to improve starting performance of the fluorescent lamps. That is, the inverter ballast circuit, which employs a soft-starting circuit and soft-switching techniques to implement the power factor correction and to mitigate of power-loss and increase a life time of the fluorescent lamps, has become an attractive performance for ballasting the fluorescent lamps. In this paper, the operation and the control of the inverter ballast are described in detail and experimental results are presented. As the experimental results, when environment temperature is at -40℃, the inverter ballast circuit has low THD(4.8%) of the input current and large power factor(98%) of the lamp current. The proposed improved ballast circuit appears to be a good performance for ballasting fluorescent lamps.

• Journal of Power Electronics
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• v.17 no.5
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• pp.1127-1136
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• 2017

This paper proposes a new soft switching dual input converter for renewable energy systems. Multi-input converters are produced by combining discrete converters. These converters reduce the number of circuit elements, cost, volume and weight of the converter and provide a constant output power in different weather conditions. Furthermore, soft switching techniques can be applied to increase efficiency. In this paper, a Zero Voltage Transition (ZVT) dual input boost converter is presented. Only one auxiliary circuit is used to provide the soft switching condition for all of the semiconductor elements. The proposed converter, which is simulated by ORCAD software, is theoretically analyzed. To confirm the validity of the theoretical analysis, a prototype of proposed converter was constructed. Simulation and experimental results confirm the theoretical analysis. An efficiency comparison shows a one percent improvement at nominal loads.

• Journal of Power Electronics
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• v.13 no.6
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• pp.919-927
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• 2013

This paper proposes a Boundary Current Mode (BCM) control scheme to realize soft switching on a conventional single phase full bridge DC/AC inverter. This technique with the advantages of no auxiliary components, low cost, high efficiency, and simple in control, is attractive for micro-inverter applications. The operation principle and characteristic waveforms of the proposed soft switching technique are analyzed in theory. A digital controller is provided based on that theory. To balance the requirements of efficiency, switching frequency, and inductor size, the design considerations are discussed in detail to guide in BCM inverter construction. A 150W prototype is built under these guidelines to implement the BCM control scheme. Simulation and experiment results demonstrate the feasibilities of the proposed soft switching technique.

• Proceedings of the KIPE Conference
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• 2002.07a
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• pp.364-369
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• 2002

Presently, a high frequency switching technique is used for a converter design to reduce its size and weight. However an increased switching frequency introduces a high switching loss. To the reduce switching loss, soft switching techniques using ZVS and ZCS are applied. It is very important to improve efficiency. However In general to develop new converter circuits, the efficiency and other performance parameters can be determined after design, implementation and experiments. The idea in this paper is to determine and predict efficiency and other operating characteristics without realization and experiments. Thereby a complex design and implementation can be avoided. PSPICE is used as a simulation tool. This is verified by comparing simulation and experiments results of the two different soft switching converters.

• Journal of Power Electronics
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• v.15 no.2
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• pp.479-486
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• 2015

The application of soft-switching techniques is increasing in the DC/DC converter area. It is important to design soft-switching parameters to ensure the converter operates properly and efficiently. An optimized design method is presented in this paper. The objective function is the total power loss of a converter, while the variables are soft-switching parameters and the constraints are the electrical requirements for soft-switching. Firstly, a response surface methodology (RSM) model with a high precision is built, and the rough optimized parameters can be obtained with the help of a genetic algorithm (GA) in the solution space determined by the constraints. Secondly, a re-optimization is conducted with a SPICE model and a GA, and accurate optimized parameters can be obtained. Simulation and experiment results show that the proposed method performs well in terms of a wide adaptability, efficiency, and global optimization.

• Journal of Power Electronics
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• v.18 no.1
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• pp.137-146
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• 2018

This paper describes a single pulse-width modulation control strategy using the Single Pulse-Width Modulation (SPWM) method with a soft-switching technique for a wide range of output voltages from a bidirectional Dual-Active Bridge (DAB) converter. This method selects two typical inductor current waveforms for soft-switching, and proposes a rule that makes it possible to achieve soft-switching without any compensation algorithm from the waveforms. In addition, both the step-up and step-down conditions are analyzed. This paper verifies that the leakage inductance is independent from the rule, which makes it easier to apply in DAB converters. An integrated algorithm, which includes step-up and step-down techniques, is proposed. The results of experiments conducted on a 50-kW prototype are presented. The system efficiency is experimentally verified to be from 85.6% to 97.5% over the entire range.