• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.2B no.4
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• pp.183-190
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• 2002

This paper presents an improved Zero Voltage/Zero Current Switching (ZVZCS) commutation cell with minimum additional components, which provides soft switching at both turn-on and turn-off of main and auxiliary switches as well as diodes in a PWM DC/DC converter. The proposed soft-switching technique is suitable for not only minority, but also majority carrier semiconductor devices. The auxiliary switch of the proposed ZVZCS commutation cell is in parallel with the main switch, and therefore, the main switch and the diode are free of currentstress. The operation principles of the proposed ZVZCS commutation cell are theoretically analyzed using the PWM boost converter topology as an example. The validity of the PWM boost converter topology with the proposed ZVZCS commutation cell is verified through theoretical analysis, simulation and experimental results.

• Proceedings of the KIPE Conference
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• 2001.10a
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• pp.227-231
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• 2001

A new primary-side-assisted zero-voltage and zero-current switching (ZVZCS) three-level DC-DC converter with flying capacitor is proposed. The three-level converters are promising in high voltage applications, and ZVZCS is a very effective means for reducing switching losses. The proposed DC-DC converter uses only one auxiliary transformer and two diodes to obtain ZCS for the inner leg. It has a simple and robust structure, and offers soft-switching capability even in short-switching conditions. The proposed converter was verified by experiments in a 6KW prototype designed for communication applications and operating at 100kHz.

• 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.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.6
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• pp.972-981
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• 2008

A New ZVS(Zero Voltage Switching) and ZVZCS(Zero Voltage and Zero Current Switching) Three-Level Converter is proposed. The proposed converter presented in this paper used a phase shift control with a flying capacitor in the primary side to achieve ZVS for the all switch. A primary auxiliary circuit, which consists of one coupled inductor, is added in the primary to provide ZVZCS conditions to primary switches. Many advantages including simple circuit topology high efficiency, and low cost make this converter attractive for high power applications. The principle of operation, feature and design considerations are illustrated and verified through the experiment with a 2kW(27V, 74A) 40 kHz IGBT based experimental circuit.

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.79-84
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• 1998

A novel zero voltage and zero current switching (ZVZCS) full bridge (FB) PWM converter with low output current ripple is presented. A simple auxiliary circuit added in the secondary provides ZVZCS conditions to primary switches, ZVS for leading-leg switches and ZCS for lagging-leg switches, as well as reduces the output current ripple (ideally zero ripple). The auxiliary circuit includes neither lossy components nor additional active switches which are demerits of the previously presented ZVZCS converters. Many advantages including simple circuit topology, high efficiency, low cost and low current ripple make the new converter attractive for high performance high power (＞1kW) applications. The principle of operation, features and design considerations are illustrated and verified on a 2.5kW, 100KHz IGBT based experimental circuit.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.51 no.12
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• pp.682-690
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• 2002

The conventional three-level high frequency phase-shifted dc/dc converter has a disadvantage that a circulating current flows through transformer and switching devices during the freewheeling interval.. 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 three-level 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 7㎾, 30KHz experimental prototype.

• Journal of Power Electronics
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• v.19 no.2
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• pp.353-362
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• 2019

To address the problem of circulating current loss in the traditional zero-current switching (ZCS) full-bridge (FB) DC/DC converter, a ZCS FB DC/DC converter topology and modulation strategy is proposed in this paper. The strategy can achieve ZCS turn on and zero-voltage and zero-current switching (ZVZCS) turn off for the primary switches and realize ZVZCS turn on and zero-voltage switching (ZVS) turn off for the auxiliary switches. Moreover, its resonant circuit power is small. Compared with the traditional phase shift full-bridge converter, the new converter decreases circulating current loss and does not increase the current stress of the primary switches and the voltage stress of the rectifier diodes. The diodes turn off naturally when the current decreases to zero. Thus, neither reverse recovery current nor loss on diodes occurs. In this paper, we analyzed the operating principle, steady-state characteristics and soft-switching conditions and range of the converter in detail. A 740 V/1 kW, 100 kHz experimental prototype was established, verifying the effectiveness of the converter through experimental results.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.48 no.6
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• pp.342-348
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• 1999

A new welding machine which adopts zero voltage and zero current switching(ZVZCS) full bridge(FB) DC-DC converter is proposed. The proposed ZVZCS FB DC-DC converter uses auxiliary transformer to obtain ZCS for leading leg. It has capability of controlling load current even in short circuit condition and is suitable for arc welding machines. The power rating of the auxiliary transformer is about one 5th to one 10th of the main transformer. Experimental results for 10KW prototype are shown to verify the principle of operation.

• Journal of Power Electronics
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• v.18 no.2
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• pp.375-382
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• 2018

A novel active controlled primary current cutting-off zero-voltage and zero-current switching (ZVZCS) PWM three-level dc-dc converter (TLC) is proposed in this paper. The proposed converter has some attractive advantages. The OFF voltage on the primary switches is only Vin/2 due to the series connected structure. The leading-leg switches can obtain zero-voltage switching (ZVS), and the lagging-leg switches can achieve zero-current switching (ZCS) in a wide load range. Two MOSFETs, referred to as cutting-off MOSFETs, with an ultra-low on-state resistance are used as active controlled primary current cutting-off components, and the added conduction loss can be neglected. The added MOSFETs are switched ON and OFF with ZCS that is irrelevant to the load current. Thus, the auxiliary switching loss can be significantly minimized. In addition, these MOSFETs are not series connected in the circuit loop of the dc input bus bar and the primary switches, which results in a low parasitic inductance. The operation principle and some relevant analyses are provided, and a 6-kW laboratory prototype is built to verify the proposed converter.

• Proceedings of the KIEE Conference
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• 2009.04b
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• pp.161-164
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• 2009

This paper presents the ZVZCS(Zero Voltage and Zero-Current-Switching) Three-Level converter using the secondary coupled inductor and auxiliary capacitor. The converter with phase-shift control is proposed to reduce the circulating loss in primary and the voltage stress in secondary side. Using a coupled winding of the output inductor, two auxiliary capacitors are generated to reset the primary current at circulating interval.