• Proceedings of the KIPE Conference
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• 2005.07a
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• pp.286-288
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• 2005

Conventional phase shift full bridge (PSFB) converter has serious voltage oscillation problem across the secondary rectifier diodes, which would require the dissipate snubber circuit, thus degrades the overall efficiency. To overcome this problem, a new voltage oscillation reduction technique (VORT) which effectively reduce the voltage oscillation of the secondary rectifier diodes for phase shift 1011 bridge converter is proposed. Therefore, no dissipate snubber for rectifier diodes is needed. In addition, since it has wide zero voltage switching (ZVS) range, high efficiency can be achieved. Operational principle, analysis of voltage oscillation, and design consideration are presented compare with that of the conventional PSFB converter. To confirm the validity of the proposed VORT, experimental results from a 420W, 385Vdc/210Vdc prototype are presented.

• Proceedings of the KIEE Conference
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• 1998.11a
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• pp.147-149
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• 1998

In this paper, zero voltage switched half bridge converter and an active-clamped, zero voltage switched forward converter equipped with self-driven synchronous rectifier is designed and investigated for high efficiency BC-DC converter. A synchronous rectifier is has a lower conduction power loss than shottky diode rectifier. The purpose of this paper is to investigate the effect of parasitic inductance in a synchronous rectifier of DC-DC converters and examine overall efficiency of zero voltage switched DC-DC converters.

• Proceedings of the KIPE Conference
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• 2004.07b
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• pp.551-555
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• 2004

The two-transformer full bridge (TTFB) PWM converter has two transformers which act as the output inductor as well as the main transformer, i.e. as the forward and the flyback transformer. Although the doubled leakage inductor of the TTFB makes it easier to achieve the zero-voltage switching (ZVS) of the lagging leg switch along the wide load range, it instigates a serious voltage ringing in the secondary rectifier diodes, which would require the dissipative snubber circuit, cause the serious power dissipation, and increase the voltage stress across those diodes. To overcome these problems, a, new lossless diode-clamp rectifier (LDCR) is employed as the output rectifier, which helps the voltage across rectifier diodes to be clamped on a half the output voltage $(V_o/2)$ or the output voltage $(V_o)$. Therefore, no dissipative snubber for rectifier diodes is needed and a high efficiency as well as low noise output voltage can be realized. The operations, analysis and design consideration of proposed converter are presented in this paper. To verify the validity of the proposed converter, experimental results from a 425W, 385-170Vdc prototype for the plasma display panel (PDP) sustaining power module (PSPM) are presented.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.2
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• pp.333-338
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• 2008

In this paper, a new NMOS current-mirror type bridge rectifier for driving RFID chips, whose minimum input voltage required to obtain the effective DC output voltage is low enough and whose power dissipation can be reduced than that of conventional one, is proposed. The designed rectifier is able to supply high enough and well-rectified DC voltages to drive RFID transponder chips for the frequency range of 13.56 MHz HF(for ISO 18000-3), 915 MHz UHF(fur ISO 18000-6), and 2.45 GHz microwave(for ISO 18000-4). Output characteristics of the proposed rectifier are analyzed with the high frequency equivalent circuit. And the circuitry method for effective reducing of the gate leakage current due to the increasing of operating frequency is also proposed theoretically. Using this method, the power consumption of $100\;{\mu}W$ and the DC output voltage of 2.13V for 3V peak-to-peak input voltage and $45\;K{\Omega}$ load resistance are obtained. Compared to conventional one, the proposed rectifier operates in more stable and shows superior characteristics in UHF and microwave frequencies.

• Proceedings of the KIEE Conference
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• 2007.04c
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• pp.201-204
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• 2007

This paper proposes a improvement of switching converter's input wave form using VIENNA Rectifier(three-phase three-switch three-level PWM Rectifier). VIENNA Rectifier is based on the combination of a three-phase diode bridge and dc/dc boost converter. It can be available to get sinusoidal mains current, and low-blocking voltage stress on rower transistors. In addition, it can control output voltage.

• Journal of IKEEE
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• v.22 no.2
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• pp.393-401
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• 2018

In this paper, a rectifier for WPC / A4WP wireless power transmission is designed. The proposed rectifier supports both WPC (Wireless Power Consortium) and A4WP (Alliance For Wireless Power) and is designed with full-bridge rectifier. WPC transmits power at the frequency of 100kHz to 205kHz and A4WP at the frequency of 6.75MHz. Since the bridge rectifier uses a MOSFET instead of a diode, the reverse current flows and the efficiency is affected if the output voltage is higher than the input voltage. Therefore, we added the reverse current detector that detects the current flowing through the MOSFET and shut off the reverse current. The frequency discriminator is used because the rectifier has different frequency band. The proposed rectifier was designed using $0.35{\mu}m$ CMOS high voltage process. The input voltage is up to 18V and the rectifier operates at 100kH to 205kHz, 6.78MHz frequency. The maximum efficiency is 94.8% and the maximum power transfer is 5.78W.

• The Transactions of the Korean Institute of Power Electronics
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• v.10 no.6
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• pp.598-609
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• 2005

Conventional phase shift full bridge (PSFB) converter has serious voltage oscillation problem across the secondary rectifier diodes, which would require the dissipate snubber circuit, thus degrades the overall efficiency. To overcome this problem a new simple voltage oscillation reduction technique (VORT) which effectively reduce the voltage oscillation of the secondary rectifier diodes for phase shift full bridge converter is proposed. Therefore, no dissipate snubber for rectifier diodes is needed. In addition, since it has wide zero voltage switching (ZVS) range, high efficiency can be achieved. Operational principle, analysis of voltage oscillation, and design consideration are presented compare with that of the conventional PSFB converter. To confirm the validity of the proposed VORT, experimental results from a 420W prototype are presented.

• Journal of Power Electronics
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• v.9 no.2
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• pp.133-145
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• 2009

In this paper a modular high performance MV-to-LV rectifier based on a cascaded H-bridge rectifier is presented. The proposed rectifier can directly connect to the medium voltage levels and provide a low-voltage and highly-stable DC interface with the consumer applications. The input stage eliminates the necessity for heavy and bulky step-down transformers. It corrects the input power factor and maintains the voltage balance among the individual DC buses. The second stage includes the high frequency parallel-output DC/DC converters which prepares the galvanic isolation, regulates the output voltage, and attenuates the low frequency voltage ripple ($2f_{line}$) generated by the first stage. The parallel-output converters can work in interleaving mode and the active load-current sharing technique is utilized to balance the load power among them. The detailed analysis for modeling and control of the proposed structure is presented. The validity and performance of the proposed topology is verified by simulation and experimental results.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.45 no.6
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• pp.10-15
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• 2008

In this paper, a new NMOS gate cross-connected current-mirror type bridge rectifier for UHF RFID applications is presented. The DC converting characteristics of the proposed rectifier are analyzed with the high frequency equivalent circuit and the gate capacitance reduction technique for reducing the gate leakage current due to the increasing of operating frequency is also proposed theoretically by circuitry method. As the results, the proposed rectifier shows nearly same DC output voltages as the existing NMOS gate cross-connected rectifier, but it shows the gate leakage current reduced to less than 1/4 and the power consumption reduced more than 30% at the load resistor, and it shows more stable DC supply voltages for the valiance of load resistance. In addition, the proposed rectifier shows high enough and well-rectified DC voltages for the frequency range of 13.56MHz HF(for ISO 18000-3), 915MHz UHF(for ISO 18000-6), and 2.45 GHz microwave(for ISO 18000-4). Therefore, the proposed rectifier can be used as a general purpose one to drive RFID transponder chips on various RFID systems which use specified frequencies.

• Journal of Power Electronics
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• v.15 no.5
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• pp.1158-1167
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• 2015

In this paper, a new hybrid DC-DC converter is proposed for electric vehicle 3.3 kW on-board battery charger applications, which can be modulated in a phase-shift manner under a fixed frequency or frequency variation. By integrating a half-bridge (HB) LLC series resonant converter (SRC) into the conventional phase-shift full-bridge (PSFB) converter with a full-bridge rectifier, the proposed converter has many advantages such as a full soft-switching range without duty-cycle loss, zero-current-switching operation of the rectifier diodes, minimized circulating current, reduced filter inductor size, and better utilization of transformers than other hybrid dc-dc converters. The feasibility of the proposed converter has been verified by experimental results under an output voltage range of 250-420V dc at 3.3 kW.