• The Transactions of the Korean Institute of Electrical Engineers B
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• v.53 no.8
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• pp.517-524
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• 2004

In this paper, a novel zero-voltage-switching(ZVS) resonant DC-DC converter is proposed. It is composed of two symmetrical active-clamped circuits, the converter can be achieve ZVS in each switches. Also, active clamp capacitor ratios($\alpha$) of proposed circuit can be reduce a peak stress of switching voltage for each main switch. Simulation results using Pspice 9.2 ver and $C^{++}$ characteristic analysis show a provement for the validity of theoretical analysis. The analysis of the proposed Current-Fed Push Pull type DC-DC converter is generally described by using normalized parameter, and achieved an evaluated characteristic values which is needed to design a circuit. We confirm a rightfulness theoretical analysis by comparing a theoretical values and experimental values obtained from experiment using MOSFET as switching devices.

• Journal of Power Electronics
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• v.13 no.4
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• pp.626-635
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• 2013

An analysis of the junction capacitance in resonant rectifiers which has a significant impact on the operating point of resonance circuits is studied in this paper, where the junction capacitance of the rectifier diode is to decrease the resonant current and output voltage in the circuit when compared with that in an ideal rectifier diode. This can be represented by a simplified series resonant equivalent circuit and a voltage transfer function versus the normalized operating frequency at varied values of the resonant capacitor. A low voltage to high voltage push-pull DC/DC resonant converter was used as a design example. The design procedure is based on the principle of the half bridge class-DE resonant rectifier, which ensures more accurate results. The proposed scheme provides a more systematic and feasible solution than the conventional resonant push-pull DC/DC converter analysis methodology. To increase circuit efficiency, the main switches and the rectifier diodes can be operated under the zero-voltage and zero-current switching conditions, respectively. In order to achieve this objective, the parameters of the DC/DC converter need to be designed properly. The details of the analysis and design of this DC/DC converter's components are described. A prototype was constructed with a 62-88 kHz variable switching frequency, a 12 $V_{DC}$ input voltage, a 380 $V_{DC}$ output voltage, and a rated output power of 150 W. The validity of this approach was confirmed by simulation and experimental results.

• Journal of Korea Society of Digital Industry and Information Management
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• v.19 no.1
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• pp.57-76
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• 2023

This study analyzes the factors and effects on the users' intention to switch from contact center-oriented to AI chatbot-oriented customer services by combining Push-Pull-Mooring Model and provides insights for companies considering the adoption of AI chatbots. To test the model, we surveyed users with experience using chatbots at least once across different age groups. Finally, we analyzed 176 cases for the analysis using IBM SPSS Statistics and SmartPLS 4.0. The results of hypotheses testing rejected the hypotheses for variables of inconsistent quality and low availability of push factors and low switching cost of mooring factor while accepting the hypotheses for the tardy response of push factors and all pull factors. Therefore, these findings provide important implications for researchers and practitioners who wish to conduct research or adopt AI chatbots. In conclusion, users do not feel inconvenienced by the contact center-oriented service but also perceive high trust and convenience with AI chatbot-oriented service. However, despite low switching costs, users consider chatbots a complementary tool rather than an alternative. So, companies adopting AI chatbots should consider what features the users expect from AI chatbots and facilitate these features when implementing AI chatbots.

• The Transactions of the Korean Institute of Power Electronics
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• v.18 no.4
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• pp.403-411
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• 2013

This paper proposes an isolated bidirectional three-phase push-pull dc-dc converter for high power application such as eco-friendly vehicles, renewable energy systems, energy storage systems, and solid-state transformers. The proposed converter achieves ZVS turn-on of all switches and volume of passive components is small by an effect of three-phase interleaving. The proposed converter has identical switching pattern for both boost and buck mode, and therefore can provide seamless characteristic at the mode transition. A 3kW prototype of the proposed converter has been built and tested to verify the validity of the proposed operation.

• Journal of Power Electronics
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• v.18 no.4
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• pp.965-974
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• 2018

A new zero-voltage-switching (ZVS) push-pull pulse-width modulation (PWM) converter is proposed in this paper. The wide ZVS condition for all of the switches is obtained by utilizing the energy stored in the output inductor and magnetizing inductance. As a result, the switching losses can be dramatically reduced. A simple auxiliary circuit including two small diodes and one capacitor is added at the secondary side of a high frequency (HF) transformer to reset the primary current during the circulating stage and to clamp the voltage spike across the rectifier diodes, which enables the use of low-voltage and low-cost diodes to reduce the conducting and reverse recovery losses. In addition, there are no active devices or resistors in the auxiliary circuit, which can be realized easily. A detailed steady operation analysis, characteristics, design considerations, experimental results and a loss breakdown are presented for the proposed converter. A 500 W prototype has been constructed to verify the effectiveness of the proposed concept.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 1999.11a
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• pp.189-194
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• 1999

This paper proposes a current-fed type high frequency inverter using a soft switching technology Zero-Voltage-Switching to reduce turn on and off loss at the switching. The analysis of the proposed circuit was described by using normalized parameter and operating characteristics have been evaluated as to switching frequency and parameters. The theoretical results are in good agreement with the experimental ones. In the future the proposed circuit is considered to be useful for induction heating applications.

• Journal of Power Electronics
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• v.6 no.2
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• pp.95-103
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• 2006

In this paper, a novel prototype of auxiliary switched capacitor assisted voltage source soft switching PWM Single-Ended Push Pull (SEPP) series capacitor compensated load resonant inverter with two auxiliary edge resonant lossless inductor snubbers is proposed and discussed for small scale consumer high-frequency induction heating (IH) appliances. The operation principle of this inverter is described by using switching mode equivalent circuits. The newly developed multi resonant high-frequency inverter using trench gate IGBTs can regulate its output AC power via constant frequency edge-resonant associated soft switching commutation by using an asymmetrical PWM control or duty cycle control scheme. The brand-new consumer IH products which use the newly proposed edge-resonant soft switching PWM-SEPP type series load resonant high-frequency inverters are evaluated using power regulation characteristics, actual efficiency vs. duty cycle and input power vs. actual efficiency characteristics. Their operating performance compared with some conventional soft switching high-frequency inverters for IH appliances is discussed on the basis of simulation and experimental results. The practical effectiveness of the newly proposed soft switching PWM SEPP series load resonant inverter is verified from an application point of view as being suitable for consumer high-frequency IH appliances.

• Transactions of the Korean hydrogen and new energy society
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• v.19 no.5
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• pp.417-422
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• 2008

In this paper, a novel DC/DC low-voltage high-current converter circuit is proposed to improve the efficiency of power converter used in the grid-connected fuel-cell generator system. We proposed a novel high efficiency grid-connected power conditioning system for RPG fuel cell. On the result of that, the loss of system was decreased rapidly by driving stack within the condition of maximum efficiency. The peak currents of the current-type inductor and the transformer's coil are reduced by synchronizing switching frequency of Buck-type converter is increased twice as the Push-Pull converter's switching frequency. The novel structure of DC/DC converter is able to realize ZVS-ZCS in fuel-cell system is proposed. The proposed switching component of Push-Pull converter has the ZVS and ZCS function by using the circuit of new passive clamp.

• Proceedings of the KIPE Conference
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• 2003.07a
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• pp.36-39
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• 2003

The push pull forward converter is a very suitable circuit for low output voltage, high output current applications with a wide input voltage range. All the magnetic components (output inductor, transformer, input filter) can be integrated into a single core. The integrated magnetics can reduce the number of the magnetic components. Developed the push pull forward converter rating are of 36 $\~$72V input and 3.3V/30A output. In this converter, the efficiency was measured by $76.4\%$ at full load and 82.95$\%$ at full load. The maximum efficiency is up to 83.$\%$ at 200kHz switching frequency, l1A output.

• Journal of Korea Trade
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• v.26 no.6
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• pp.20-40
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• 2022

Purpose - In recent times, the international trade environment has been changing rapidly, centering on the online market. In the post-COVID-19 era, small and medium-sized trading companies are facing the problem of not being properly provided with overseas market research, market trend analysis, and trade-related information. Cloud-based digital trade is being sought as an alternative to solve these problems; however, there is a lack of research on the intention to switch to digital trade among small and medium-sized trading companies. Therefore, this study empirically analyzes the intention to switch to digital trade based on the migration theory, and through this, attempts to identify each factor that affects the intention to switch to digital trade. Design/methodology - In this study, in order to identify factors influencing intention to switch to digital trade and innovation resistance of small and medium-sized trading companies, through previous research on migration theory and the PPM (Push, Pull, Mooring) model, each variable was selected for the purpose of the study. Based on this, a research model was established for the factors affecting switching to digital trade of small and medium-sized trading companies and empirically analyzed. In addition, considering the differences in the innovation propensity and maturity of information infrastructure of trading companies as the recipients of innovation, this study analyzes the moderating effect of the mooring effect and seeks ways to establish specific strategies according to the degree. Findings - As a result of empirical analysis, the pull effect was found to have the greatest influence on intention to switch to digital trade. However, the pull factor was found to have an effect on user resistance, and it was confirmed that it was a factor simultaneously inducing positive and negative consumption behaviors among users. In addition, it was found that the higher the company's innovation propensity, the higher the pull effect's influence on the intention to switch, and analysis showed that the push effect had no influence. In addition, companies with high information infrastructure maturity were expected to have a relatively high level of intention to switch compared to companies with low information infrastructure maturity, and the difference between the two groups was found not to be statistically significant. Originality/value - This study is a timely study in that it demonstrated the effect on the switching to cloud-based digital trade for small and medium-sized trading companies and that the cloud system related to digital trade is in full swing. There are academic implications in that it revealed that the pull effect is an important factor in the intention to switch to cloud service. Practical implications were presented in that small and medium-sized trading companies suggested ways to increase the value of the cloud system for switching to digital trade and a way to increase the switching ratio by minimizing the mooring effect. In addition, the study argues that active institutional support from the government is needed to activate cloud service.