• Journal of Electrical Engineering and Technology
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• v.13 no.1
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• pp.256-262
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• 2018

This study introduces a novel Soft Switching (SS) Pulse Width Modulated (PWM) AC-DC boost converter. In the proposed converter, the main switch is turned on with Zero Voltage Transition (ZVT) and turned off with Zero Current Transition (ZCT). The main diode is turned on with Zero Voltage Switching (ZVS) and turned off with Zero Current Switching (ZCS). The auxiliary switch is turned on and off with ZCS. All auxiliary semiconductor devices are turned on and off with SS. There is no extra current or voltage stress on the main semiconductor devices. The majority of switching energies are transferred to the output by auxiliary transformer. Thus, the current stress of auxiliary switch is significantly reduced. Besides, the proposed converter has simple structure and ease of control due to common ground. The theoretical analysis of the proposed converter is verified by a prototype with 100 kHz switching frequency and 500 W output power. Furthermore, the efficiency of the proposed converter is 98.9% at nominal output power.

• Journal of IKEEE
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• v.25 no.4
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• pp.741-749
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• 2021

This paper presents the current-fed type LLC AC to DC high frequency resonant converter capable of ZVZCS(Zero-Voltage and Zero-Current Switching). The current-fed type LLC AC to DC high frequency resonant converter proposed in this paper could operate not only in ZVS(Zero-Voltage Switching) operation by connecting the resonant capacitors(C₁, C₂) in parallel across the switching devices but also in ZCS(Zero-Current Switching) operation of the secondary diode. The ZVS and ZCS operations can reduce the turn-on loss of the switching devices and the turn-off loss of the secondary diodes, respectively. The circuit analysis of current-fed type LLC AC to DC high frequency resonant converter proposed in this paper is addressed generally by adopting the normalized parameters. The operating characteristics of proposed LLC AC to DC high frequency resonant converter were also evaluated by using the normalized control parameters such as the normalized control frequency(μ), the normalized load resistor(λ) and so on. Based on the characteristic values through the characteristics of evaluation, an example of the design method of proposed LLC AC to DC high frequency resonant converter is suggested, and the validity of the theoretical analysis is confirmed using the experimental results and PSIM simulation.

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.1056-1061
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• 1998

In this paper, a novel zero current switching (ZCS) high frequency inverter for induction heating is proposed. The ZCS characteristics are investigated from both the numerical analysis and the experiment.

• Journal of Electrical Engineering and Technology
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• v.13 no.4
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• pp.1539-1548
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• 2018

This paper introduces a new soft switched AC-DC boost converter with power factor correction (PFC). In the introduced converter, all devices are turned on and off under soft switching (SS). The main switch is turned on under zero voltage transition (ZVT) and turned off under zero current transition (ZCT). The main diode is turned on under zero voltage switching (ZVS) and turned off under zero current switching (ZCS). Meanwhile, there is not any current or voltage stress on the main devices. Besides, the auxiliary switch is turned on under ZCS and turned off under ZVS. The detailed theoretical analysis of the converter is presented, and also theoretical analysis is verified by a prototype with 100 kHz and 500 W. Also, the proposed converter has 99.8% power factor and 97.5% total efficiency at soft switching operation.

• The Transactions of the Korean Institute of Power Electronics
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• v.11 no.1
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• pp.14-21
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• 2006

This paper presents a Zero-Current Switching(ZCS) two-transformer phase-shifted full-bridge(TTFB) converter using voltage ripple. The proposed converter provides Zero-Voltage Switching(ZVS) of leading leg switches and ZCS of lagging leg switches using voltage ripple. Especially, circulating current is reduced by ZCS operation and there are no additional components required for the soft switching of power switches. Furthermore, in case of light load, ZVS operation of lagging leg can be achieved. The operations, analysis and design consideration of proposed converter are presented. To verify the validity of the proposed converter, experimental results for a 410W (205[V], 2[A]) prototype are presented.

• Proceedings of the KIPE Conference
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• 2005.07a
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• pp.436-438
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• 2005

This paper presents a Zero-Current Switching(ZCS) two-transformer phase-shift full-bridge(TTFB) converter using voltage ripple. The proposed converter provides Zero-Voltage Switching(2VS) of leading leg switches and ZCS of lagging leg switches using volt-age ripple. Especially, circulating current Is reduced by ZCS operation and there are no additional components required for the soft switching of power switches. Furthermore, in case of light load, ZVS operation of lagging leg can be achieved. The operations, analysis and design consideration of proposed converter are presented. To verify the validity of the proposed converter, experimental results for a flow (205V, 2A) prototype are presented.

• Proceedings of the KIPE Conference
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• 2007.11a
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• pp.133-135
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• 2007

This research presented the new zero-current switching pulse width modulation SEPP(Single Ended Push-Pull)high frequency inverter for solving the problem of the zero-current SEPP high frequency inverter circuit which is using widely in the practical application of an induction heating apparatus, the soft switching operation and power control are impossible when the lowest power supply in the zero-current switching pulse width modulation SEPP high frequency inverter. The inverter circuit which is attempted by on-off operation of a switch has the reduction effect of the power loss due to a soft switching and a high frequency switching. And it confirmed that the power regulation is possible continuously from 0.25[kW] until 2.84[kW] in the case the duty rate(D) changes from 0.08 to 0.3 under zero-current switching operating by a dissymmetry pulse width modulating control and the power conversion efficiency comes true the efficiency of 95[%]. Due to the result above, the ZCS PWM SEPP high frequency inverter will be effective as sources of an induction heating apparatus.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2008.10a
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• pp.241-243
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• 2008

This research presented the new zero-current switching pulse width modulation SEPP(Single Ended Push-Full)high frequency inverter for solving the problem of the zero-current SEPP high frequency inverter circuit which is using widely in the practical application of an induction heating apparatus, the soft switching operation and power control are impossible when the lowest power supply in the zero-current switching pulse width modulation SEPP high frequency inverter. The inverter circuit which is attempted by on-off operation of a switch has the reduction effect of the power loss due to a soft switching and a high frequency switching. And it confirmed that the power regulation is possible continuously from 0.25[kW] until 2.84[kW] in the case the duty rate(D) changes from 0.08 to 0.3 under zero-current switching operating by a dissymmetry pulse width modulating control and the power conversion efficiency comes true the efficiency of 95[%]. Due to the result above, the ZCS PWM SEPP high frequency inverter will be effective as sources of an induction heating apparatus.

• Proceedings of the KIEE Conference
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• 2003.10b
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• pp.209-212
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• 2003

This paper proposes a soft-transition control strategy for a three phase ZCS(Zero Current Switching) inverter circuit. Each phase leg of inverter circuit consists of an LC resonant tank, two main switches, and one auxiliary switches. This paper presents design consideration via a study example of a three phase prototype inverter for motor drives. A simple device tester with zero current switching capability is proposed to select eligible auxiliary switches. The principle of operation, feature and design considerations are illustrated and verified through the experiment with a 2.2kW 5kHz IGBT based experimental circuit.

• Smart Structures and Systems
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• v.25 no.3
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• pp.385-391
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• 2020

In this paper, a new passive lossless snubber circuit with energy transfer capability is proposed. The proposed lossless snubber circuit provides Zero-Current Switching (ZCS) condition for turn-on instants and Zero-Voltage Switching (ZVS) condition for turn-off instants. In addition, its diodes operate under soft switching condition. Therefore, no significant switching losses occur in the converter. Since the energy of the snubber circuit is transferred to the output, there are no significant conduction losses. The proposed snubber circuit can be applied on isolated and non-isolated converters. To verify the operation of the snubber circuit, a boost converter using the proposed snubber is implemented at 70W. Also, the measured conducted Efficiency Electromagnetic Interference (EMI) of the proposed boost converter and conventional ones are presented which show the effects of proposed snubber on EMI reduction. The experimental results confirm the presented theoretical analysis.