• Proceedings of the KIPE Conference
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• 2008.06a
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• pp.370-372
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• 2008

A resonant converter suitable for applications of wide input variation is proposed. A half-bridge converter and a phase-shift converter are combined in primary and the secondaries of each transformer are connected in series which makes four voltage levels. Furthermore, by adopting resonant converter scheme, a resonant capacitor is connected with the secondaries of the transformers in series and an output inductor is removed. Zero voltage switching is achieved from full load to no load. The analysis of the resonant converter and experimental results of 200W prototype is presented to verify the features of the converter.

• Journal of Power Electronics
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• v.15 no.4
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• pp.876-885
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• 2015

High frequency alternating current (HFAC) has been widely used in a wide range of power distribution systems (PDS) due to its superior performance. A high frequency AC/DC converter plays the role of converting HFAC voltage to DC voltage. In this paper, a new LCL-T resonant AC/DC converter has been proposed, and an easier control method based on input voltage comparison is presented, without the complicated calculation of the zero-crossing point. Both a low distortion and near-to-unity power factor can be achieved by the proposed resonant converter and control strategy. The operational principle and steady-state analysis are given for the proposed resonant converter. A simulation model and experimental prototype are implemented with an operation frequency of 25kHz and a rated power of 20W. The simulation and experimental results verify the accuracy of the analysis and the excellent performance of the proposed topology.

• Journal of Power Electronics
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• v.14 no.5
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• pp.882-889
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• 2014

This paper presents a zero voltage switching (ZVS) converter with three resonant tanks. The main advantages of the proposed converter are its ability to reduce the switching losses on the power semiconductors, decrease the current stress of the passive components at the primary side, and reduce the transformer secondary windings. Three resonant converters with the same power switches are adopted at the low voltage side to reduce the current rating on the transformer windings. Using a series-connection of the transformer secondary windings, the primary side currents of the three resonant circuits are balanced to share the load power. As a result, the size of both the transformer core and the bobbin are reduced. Based on the circuit characteristics of the resonant converter, the power switches are turned on at ZVS. The rectifier diodes can be turned off at zero current switching (ZCS) if the switching frequency is less than the series resonant frequency. Therefore, the reverse recovery losses on the rectifier diodes are overcome. Experiments with a 1.6kW prototype are presented to verify the effectiveness of the proposed converter.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.4 no.4
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• pp.323-328
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• 2003

In this paper new control strategy of series resonant converter system for power supply of communication station is suggested. Frequency controlled series resonant converter system is robust to load variations because it is POSR(Parallel Output Series Resonant: POSR) type. And it provides stable output voltage by changing switching frequency to input voltage variations. Firstly, operation analysis about suggested series resonant converter system was carried. Then simulations using ACSL(Advanced Continuous Simulation Langage) and experiments to actual system were carried to prove characteristics of suggested system.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.55 no.8
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• pp.423-429
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• 2006

Recently, the high frequency isolated boost DC/DC converter has been widely used for the PCS (Power Conditioning System) system because of its small size and low cost. However, the high frequency isolated boost DC/DC converters applied the conventional voltage-fed converter and current-fed converter have the problems such as the high conduction losses and the surge voltage due to the high circulating current and the leakage inductance, respectively. To overcome this problems, in this paper the secondary LLC resonant converter is proposed, and the experimental results of the secondary LLC series resonant converter for boost DC/DC converter are verified on the simulation based on the theoretical analysis and the 700W experimental prototype.

• Proceedings of the KIPE Conference
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• 1998.11a
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• pp.44-48
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• 1998

In the buck-boost DC-DC converter which is used at a certain situation such as in factories where loads often change a lot, the switches in the device make big energy loss in operating at Buck-Boost Mode due to hard switching and are affected by lots of stresses which decrease the efficiency rate of the converter. In order to improve this problem, to decrease the loss of snubber and switching, it has been investigated that zero voltage switching mode and zero current switching mode which make the operation of switches with soft switching. For the more sophisticated and advanced device, this paper is presented the Partial Resonant Soft Switching Mode Power Converter which is adapted the power converter having the partial resonant soft switching mode, that makes switches operate when the resonant current or voltage becomes zero by making the resonant circuit partially at turning on and off of the switches with suitable layout of the resonant elements and switch elements in the converter. Also, this paper includes the analysis and simulation of the Partial Resonant type Buck-Boost Chopper.

• The Transactions of the Korean Institute of Power Electronics
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• v.19 no.6
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• pp.557-563
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• 2014

This study deals with a resonant converter of an anti-start air conditioner compressor for commercial vehicles. The anti-start air conditioner compressor must generally have a high current, high efficiency, a low volume, and a low weight. To reduce the switching losses and voltage and current stresses of the device, the anti-start air conditioner compressor applies the full-bridge L-C resonant converter topology. Hardware parameters are designed to have a wide voltage range, and the switching frequency range of the L-C resonant converter is determined. Simulation is implemented using PSIM and an experiment is performed to verify the proposed converter.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.39 no.9
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• pp.934-943
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• 1990

There are no turn-on losses in the series Resonant Converter which operates above the resonance frequency, and the commutation stress on the switched component is low. For a given Series Resonant Converter with specified load resistance, the output voltage is a function of the operation frequency. This paper describes the static and dynamic characteristic analysis of the Series Resonant DC to DC Converter, which is operating above the resonant frequency, with frequency control. For the analysis method, state plane technique is adopted, and the circuit operation is defined from normalized switching frequency, Fsn. Under this condition, circuit performance is analyzed ideally. The validity of the proposed analysis is verified by comparing with experimental results, the stability of the converter is confirmed against small variations around the operating point by conventional frequency domain analysis, and the stress quantity added to switch component is shown.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.48 no.4
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• pp.212-218
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• 1999

A new partial resonant three phase boost converter with high power factor and high efficiency is proposed. The proposed boost converter is constructed by using a resonant network in parallel with the swithch of the conventional boost converter. The devices are switched at zero voltage or zero current eliminating the switching loss. A new auxiliary partial resonant boost converter achieves zero-voltage switching(ZVS) or zero-current switching(ZCS) for all switch devices without increasing their voltage and current stresses.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.7
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• pp.1366-1371
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• 2011

The resonant converter cause the high voltage stress according to the input voltage, which increases the conduction loss in converter power switches. The topology of LLC half bridge resonant converter provides ZVS characteristic and also the stress of voltage and current is smaller than that of the general resonant converters. So we can expect the higher efficiency. In this paper, the analysis of the characteristics of the converter efficiency and the best conditions for highest efficiency were investigated. As a result, the efficiency of utilizing up to 93% is achieved.