• Proceedings of the KIPE Conference
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• 2007.07a
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• pp.424-427
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• 2007

The LLC series resonant converter with a LLT (Inductor-Inductor-Transformer) transformer for PDP power supply is presented. LLT transformer used to combine the inductor and transformer into one unit has the increased leakage inductance in the primary and secondary due to the winding method and the use of the gaped core. The increased leakage inductance in the primary and secondary of LLT transformer can be impacted on the DC voltage gain characteristics of LLC series resonant converter. In this paper, DC gain characteristics and the experimental results of the LLC series resonant converter with a LLT transformer are verified on the Math-CAD simulation based on the theoretical analysis and the 600W experimental prototype.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.39 no.6
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• pp.557-567
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• 1990

This paper describes the static and dynamic characteristic analysis of the Series Resonant DC to DC Converter with frequency control. The natural commutation of all switch element is realized when the switching frequency is below the resonant frequency of the tank circuit, and the analysis is limited to only this region. For the analysis method, state plane technique is adopted, and each operation mode is defined from normalized switching frequency Fsn. Under this condition, circuit performance is analyzed ideally. The physical characteristics of the series resonant converter is easily grasped by this analysis method with frequency control and this analytical results are directly applicable to the actual converter design. The validity of the analysis is verified by comparing with experimental results and the stability of the converter is confirmed against small variations around the operating point by conventional frequency domain analysis.

• Journal of Power Electronics
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• v.15 no.2
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• pp.389-398
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• 2015

This paper presents a 1.92 kW resonant converter for medium voltage applications that uses low voltage stress MOSFETs (500V) to achieve zero voltage switching (ZVS) turn-on. In the proposed converter, four MOSFETs are connected in series to limit the voltage stress of the power switches at half of the input voltage. In addition, three resonant circuits are adopted to share the load current and to reduce the current stress of the passive components. Furthermore, the transformer primary and secondary windings are connected in series to balance the output diode currents for medium power applications. Split capacitors are adopted in each resonant circuit to reduce the current stress of the resonant capacitors. Two balance capacitors are also used to automatically balance the input capacitor voltage in every switching cycle. Based on the circuit characteristics of the resonant converter, the MOSFETs are turned on under ZVS. If the switching frequency is less than the series resonant frequency, the rectifier diodes can be turned off under zero current switching (ZCS). Experimental results from a prototype with a 750-800 V input and a 48V/40A output are provided to verify the theoretical analysis and the effectiveness of the proposed converter.

• Journal of IKEEE
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• v.25 no.1
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• pp.218-228
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• 2021

This paper presents the high-efficiency DC-DC converter using the multi-resonant-circuit. The proposed converter has the power topology of half-bridge and utilizes the multi-resonant-circuit that is composed of 2 inductors (LL) and 1 capacitor (C) to achieve high-efficiency. The multi-resonant-circuit forms each resonant circuit of series circuit type with each resonant frequency, according to the operation modes. This paper first describes the operation pirinciples of proposed converter by the operation modes and steady-state fundamental approximation modelling. Then it shows a design example of the proposed converter based on the principles. And it is validated that the proposed converter has the operation characteristics of high-efficiency DC-DC power conversion through the experimental results of prototype converter implemented by the designed circuit parameters.

• The Transactions of the Korean Institute of Power Electronics
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• v.12 no.6
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• pp.472-482
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• 2007

The LLC series resonant converter with a LLT (Inductor-Inductor-Transformer) transformer design process and experimentation results for PDP TV power supply is presented. LLT transformer used to combine the inductor and transformer into one unit has the increased leakage inductance in the primary and secondary due to the winding method and the use of the gaped core. The increased leakage inductance in the primary and secondary of LLT transformer can be impacted on the DC voltage gain characteristics of LLC series resonant converter, In this paper, DC gain characteristics and the experimental results of the LLC series resonant converter with a LLT transformer are verified on the Math-CAD simulation based on the theoretical analysis and the 600W experimental prototype.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.6 no.3
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• pp.278-284
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• 2005

In this paper, phase controlled series resonant converter (PCSRC) system for power supply of communication station is suggested. PCSRC system is robust to load variations because it is POSR (parallel output series resonant) type. And it provides stable output voltage by changing phase of MOSFET switches to input voltage variations. Firstly, operation analysis about suggested series resonant converter system was carried. Then simulations using PSIM and experiments to actual system were carried to prove characteristics of suggested system.

• Proceedings of the KIPE Conference
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• 2010.11a
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• pp.198-199
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• 2010

In this paper, bi-directional DC/DC converter using a LC series resonant converter is proposed. A proposed converter is consisted by adding LC series resonant tank into a conventional bi-directional DC/DC converter and performs soft-switching at both boost and buck mode. A LC series resonance occurs in whole operation mode and switching point is determined by specific condition. Through the theoretical analysis and simulation results, operation modes and characteristics of the proposed topology is verified.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.7
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• pp.1250-1254
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• 2007

The multi-resonant(MR) converter has a characteristics that the parasitic components existing in the converter are absorbed into the resonant circuits. The designed MR converter could be got a high efficiency and a high power density because the switching power losses are reduced effectively due to resonant switching circuit. However, the high resonant voltage stress of switching power devices leads to the conduction loss. In this paper, it is proposed the novel alternated(AT) flyback multi-resonant converter to overcome such a drawback. The suggested converter dc input is divided by two series input filter capacitors. The resonant stress voltage is reduced to 2-3 times the input voltage without any complexity and it provides the various circuit schemes in lots of applications. The proposed flyback MR converter is verified through simulation and experiment.

• 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.

• Proceedings of the KIPE Conference
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• 2004.11a
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• pp.45-48
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• 2004

To improve the efficiency characteristics in the resonant converter using the contact-less power supply with the large air-gap and the long primary winding, this paper suggests the three-level series-parallel resonant converter(SPRC). The voltage gain characteristics of the proposed converter have the unit gain in a resonance frequency point of the series and parallel, and input voltage and current in the primary of SPRC are always In phase for the all equivalent load resistance because of the parallel resonant tank of the high impedance. The results are verified on the simulation based on the theoretical analysis and the 4kW experimental prototype.