• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.27 no.4
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• pp.48-53
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• 2013

In general, the LLC resonant topology consists of three stages as; square wave generator, resonant network, and rectifier network. LLC resonant converter has the time slowly varying parameters. However, the power LEDs as the load of LLC converter can be regarded as fast time varying parameters. In this paper, the mathematical model of half-bridge resonant converter including with the power LEDs is introduced for the current controller design model. Using this controller design model, the parameter adaptive output feedback controller will be designed to control the power LEDs current. In order to show the validities of the proposed model, the parameter adaptive output feedback controller, the experimental investigation will be presented.

• Proceedings of the KIPE Conference
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• 2016.11a
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• pp.15-16
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• 2016

This paper proposes an isolated DCDC converter that consists of unregulated LLC resonant converter and non-isolated synchronous buck converter for battery charger of energy storage systems application. The unregulated converter operates as transformer with fixed duty ratio and switching frequency. The synchronous buck converter is installed in the output of the LLC resonant converter. And the converter charges and discharges the battery by controlling a current of battery. The proposed converter can get the high efficiency by separating function. This paper explains design of an unregulated converter and synchronous converter.

• The Transactions of the Korean Institute of Power Electronics
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• v.14 no.5
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• pp.397-405
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• 2009

Nowadays, power supplies for LCD TV of larger and slimmer screen size are required to have high power density and high efficient characteristics. In order to meet these requirements, Multi-phase interleaved LLC resonant converter is applied for increasing power density and reducing the current rating in the used devices. In this paper, gain characteristics and the experimental results of the proposed two-phase LLC resonant converter which implemented by the simple control circuit are verified based on the theoretical analysis and the 300W experimental prototype.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1392-1394
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• 2005

In this paper results of the experiment which used LLC resonant Half Bridge DC-DC converter to a portable electrical equipment. LLC resonant Half Bridge DC-DC converter which was used in this experiment improved an efficiency because it reduced switching, conduction losses and with synchronous rectifier. As a result of the experiment, this proposed converter could verified an increase of 2% to the efficiency more than diode rectifier.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.6
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• pp.885-890
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• 2015

LLC resonant converter has been widely used because of its high efficiency and high energy density. In this paper, we designed a LLC resonant converter as the main power supply of the Nd:YAG pulse laser. First harmonic approximation (FHA) is used to model the LLC resonant converter. FHA equivalent circuit model and the transfer function of the LLC resonant converter is proposed. Soft start technology is also used to suppress the surge current. The laser output simulation test result is identical with the practical test, the laser energy of every pulse can reach up to 2.5J, and the pulse per second (PPS) can be adjusted from 6 to 18. The power system is verified stable and reliable by both of the simulation and experiment results.

• The Transactions of the Korean Institute of Power Electronics
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• v.21 no.2
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• pp.111-116
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• 2016

This paper proposes a high-frequency (MHz) LLC resonant converter for a capacitor coupling wireless power transfer (CCWPT). The CCWPT uses electric field in the coupling capacitor between the transmitter and receiver electrodes with a dielectric layer. Given that capacitance is very small and the impedance is large, transferring power with a simple series resonance is difficult. Therefore, the high frequency (MHz) and high Q factor LLC converter is proposed to reduce the impedance of the coupling capacitance and to obtain a high output voltage. This paper deals with the operation analysis of the proposed LLC converter and a theoretical capacitance estimation. The operation and features of the proposed CCWPT LLC converter is verified with a 4.2 W prototype for charging mobile devices.

• Journal of IKEEE
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• v.23 no.3
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• pp.1108-1111
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• 2019

This paper presents the comprehensive transformer design methodology with the winding method of automatic type suitable for LLC resonant converter. The problem with conventional LLC resonant transformer is that it is difficult to implement the winding method of automatic type because all windings are wound in one bobbin. Therefore, the LLC resonant transformer, which is capable of the winding method of automatic type to multiple section bobbin without insulation tape and barrier tape, is proposed in this paper and the design procedure of the proposed LLC resonant transformer is also shown. Modeling and analysis of the proposed LLC resonant transformer using Maxwell 3D simulation tool are described in detail and a protype 150W LLC resonant converter using the proposed LLC resonant transformer manufactured by 3D modelling is also verified through the experimental test.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.8
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• pp.1101-1107
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• 2013

A light emitting diodes(LED) lighting has been increasingly used due to its low power consumption, long life time, high efficiency, and environment friendly characteristics. Also various power converters has been applied to drive these LED lighting. Among many power converters, a LLC resonant converter could be applied for LED lighting because of its high efficiency and high power density. Furthermore, the function of power factor correction(PFC) might be added. In this paper, 1-stage asymmetrical LLC resonant converter is proposed. The proposed converter performs both input-current harmonics reduction and PFC using the discontinuous conduction mode(DCM). The proposed 1-stage LLC resonant converter approach has the lower voltage stress across switching devices and achieve the zero voltage switching(ZVS) in switching devices. To verify the performance of the proposed converter, simulation and experimental results from a 300[W] prototype are provided.

• The Transactions of the Korean Institute of Power Electronics
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• v.22 no.4
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• pp.305-311
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• 2017

In this paper, the LLC resonant converter battery charger, using adaptive turn ratio scheme, is proposed to achieve high efficiency and wide range output voltage. The LLC converter high frequency transformer has an adaptively changed turn ratio by the auxiliary control circuitry. As a result, the optimal converter design with a large magnetizing inductance is easily achieved to minimize the conduction and the turn-off losses while providing widely regulated voltage gain capability to properly charge the Li-ion battery. The proposed converter operational principle and the optimal design considerations are illustrated in detail. Finally, several simulation results verify the proposed LLC resonant converter's effectiveness.

• Proceedings of the KIPE Conference
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• 2016.07a
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• pp.337-338
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• 2016

This paper introduces a novel dual Full-Bridge LLC(FBLLC)resonant converter for CC/CV Charge of the Battery for Electric Vehicles. One full-bridge LLC resonant converter operates with a fixed-resonant network and the other operates with a variable-resonant network for CC and CV mode operations. The proposed converter can achieve ZVS for all the primary switches and exhibits a highefficiency characteristics like aconventional single FBLLC resonant converter. In addition, the variable-resonant network helps minimize the switching-frequency variation. The dual structure makes the proposed converter possible to achieve ZVS and nearly ZCS for all the primary switches in CC mode operation. Since the proposed converter can operate at a fixed frequency in CV mode, it can minimize the circulating current and achieve nearly ZCS. A 6.6 kW prototype converter is implemented to verify the validity of proposed converter and the maximum efficiency of 98.3% was achieved.