• The Transactions of the Korean Institute of Power Electronics
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• v.26 no.3
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• pp.205-213
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• 2021

Due to the advantage of reducing the voltage applied to the switch semiconductor, the input series and output parallel combination is widely used in systems with high input voltage and large output current. On the other hand, the LLC converter is widely used as a high-efficiency power converter, and when connected by ISOP combination, there is a possibility that input voltage imbalance may occur due to a mismatch of passive devices. To avoid damaging the switching device, this study analyzed the DC-link voltage imbalance of a high-capacity supply using an ISOP LLC converter. In addition, the case where DC-link unbalance control was applied and the case not applied was analyzed respectively. Based on this analysis, an initial start-up algorithm was proposed to prevent input power semiconductor device damage due to DC-link over-voltage. The effectiveness of the proposed algorithm has been verified through simulations and experiments.

• Journal of Power Electronics
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• v.8 no.3
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• pp.275-279
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• 2008

An LLC series resonant converter has many unique characteristics and improvements over PWM topologies. However, many output capacitors are needed in parallel to satisfy output voltage ripple and the rated ripple current of the capacitors. This paper deals with a novel two phase interleaved LLC resonant converter using a phase of the resonant capacitor. The proposed converter can satisfy output voltage ripple and a rated ripple current of capacitors with few output capacitors, relatively. The operation and features are considered in detail and a prototype with a 12V-100A output is investigated.

• Proceedings of the KIPE Conference
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• 2017.11a
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• pp.181-182
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• 2017

In the battery system, an isolated converter is used for the stability of the system when controlling the charge and discharge of the battery. A fixed frequency LLC converter which is a type of isolated converter, has the advantage of high efficiency and power density with zero voltage switching at high frequency. Therefore, in this paper, the operation analysis, design and experimental verification of the LLC resonant converter with high efficiency and high power density for the ESS system were conducted.

• Proceedings of the KIPE Conference
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• 2008.06a
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• pp.526-528
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• 2008

LLC series resonant converter has many unique characteristics and improvement over PWM topologies. However, many output capacitors should be needed in parallel to satisfy an output voltage ripple and a rated ripple current of the capacitors. This paper is deal with a novel two phase interleaved LLC resonant converter using a phase of the resonant capacitor. The proposed converter can satisfy output voltage ripple and a rated ripple current of capacitors with few output capacitors, relatively. The operation and features is considered in detail and a prototype with a 12V-100A output is investigated.

• Journal of Power Electronics
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• v.11 no.3
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• pp.245-255
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• 2011

A novel single-stage AC/DC converter with the soft-switching characteristic based on interleaving technology and an LLC topology is proposed here. The converter is integrated by an interleaved cell and an LLC cell. Because the components of the system are reduced as a result of integrating, the cost decreases. Since interleaving technology is adopted, the converter can work in a high voltage input state. The LLC topology chosen here ensures that the switches on the primary side work in the ZVS condition and that the diodes on the secondary side work in the ZCS condition, which decreases the switching loss of the system. A theoretical analysis and the design procedures of the proposed converter are proposed and discussed in detail. Simulations and experimental studies with a 100W prototype are done to prove the analysis.

• Proceedings of the KIPE Conference
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• 2006.06a
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• pp.277-280
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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 1kW experimental prototype.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.3
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• pp.312-317
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• 2014

In this paper, I propose the design technology of LLC resonant converter for the xenon flashlamp that is used to the solid state laser. Through the fabrication of 1.5kW large scale LLC resonant converter, the discharge characteristics are carried out, and introduce the new control method for limiting inrush current by the abrupt load current changes. The mathematical modeling for the lamp discharge includes the internal loss and lamp parameters. I propose the optimal method for the driving conditions of xenon flashlamp from the simulation results comparing the real measurements.

• Journal of Power Electronics
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• v.18 no.3
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• pp.802-816
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• 2018

A digital direct phase-shift control (DDPSC) method based on the phase-shifted full-bridge LLC (PSFB-LLC) converter is presented. This work combines DDPSC with the conventional linear control to obtain a hybrid control strategy that has the advantages of linear control and DDPSC control. The strategy is easy to realize and has good dynamic responses. The PSFB-LLC circuit structure is simple and works in the fixed frequency mode, which is beneficial to magnetic component design; it can realize the ZVS of the switch and the ZCS of the rectifier diode in a wide load range. In this work, the PSFB-LLC converter resonator is analyzed in detail, and the concrete realization scheme of the hybrid control strategy is provided by analyzing the state-plane trajectory and the time-domain model. Finally, a 3 kW prototype is developed, and the feasibility and effectiveness of the DDPSC controller and the hybrid strategy are verified by experimental results.

• Proceedings of the KIEE Conference
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• 2006.07b
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• pp.1039-1040
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• 2006

The resonant converters 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 not higher than that of the general resonant converters. So we can expect the higher efficiency. In this paper, the LLC resonant converter is designed for the notebook computer adapter. In the adapter design, we should consider the weight, the size and overheat of the adapter. Thus the higher efficiency is an essential particular. First of all, the optimal design of transformer is the most important facts. Some parameters should be considered in order to get the highest efficiency. The adapter is designed through the considering of these parameters including the PFC circuit of the pre-regulator. It converts AC line input into about $400V_{DC}$ Link voltage of the LLC converter input and the converter has $16V_{DC}/90W$ ratings. The efficiency measured is about up to 92%.

• Proceedings of the KIPE Conference
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• 2018.11a
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• pp.197-198
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• 2018

This paper proposes a novel hybrid converter topology suitable for electric vehicle on-board battery chargers, which is a combination of the full-bridge (FB) and half-bridge (HB) LLC circuits. A full load controllability under wide output voltage range can be achieved with a small resonant inductance, which increases the efficiency and lowers the size and cost. Simulation results are shown to evaluate the dynamic performance of the proposed converter.