• The Transactions of the Korean Institute of Power Electronics
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• v.17 no.4
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• pp.298-305
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• 2012

This paper proposes a soft switching boost converter with an auxiliary resonant circuit. The auxiliary resonant circuit is added to a general boost converter and that is composed of one switch, one diode, one inductor and two capacitors. The resonant network helps the main switch to operate with a zero voltage switching(ZVS) and auxiliary switch also operates under the zero voltage and zero current conditions. The soft switching range is extended by the auxiliary switch and it is possible to control the proposed converter with a pulse width modulation(PWM). The ZVS and ZCS techniques make switching losses decreased and efficiency of the system improved. A theoretical analysis is verified through the simulation and experiment.

• The Transactions of the Korean Institute of Power Electronics
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• v.23 no.3
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• pp.208-216
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• 2018

In this paper, an LLC resonant converter employing two coupled inductors on the secondary side of the converter is proposed. The conventional LLC converter exhibits serious power loss during secondary winding of the transformer because of generation of tremendous output current ripples. To overcome this problem, an LLC resonant converter with a current doubler as a rectifying circuit was recently proposed. However, the current-doubler rectifying circuit requires coupled inductors with a high coupling ratio to retain the designed resonance characteristics. Therefore, an additional hardware filter is required at the output stage to address large output current ripples. Additional design procedures are also necessary because the inductance component of the added filter affects the designed resonant network. To solve this issue, an LLC resonant converter employing two coupled inductors is proposed in this paper. Mathematical analysis shows that the proposed secondary-side current-doubler circuit does not affect the designed resonance characteristics. The operating principles and theoretical analyses are proven through a simulation and experiments with a 54 V/28 A prototype.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.52 no.2
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• pp.49-55
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• 2003

This paper presents a novel three-phase current-fed Pulse Width Modulation converter with switched capacitor type resonant DC link commutation circuit operating PWM pattern strategy under a design consideration of low-pass filter, which can operate on the basis of the principle of zero current soft switching commutation. In the first place, the steady state operating principle of this converter with a new resonant DC link snubber circuit is described in connection with the equivalent operation circuit, together with the practical design procedure of the switched-capacitor type resonant DC link circuit is discussed from a theoretical viewpoint on the basis of a design example for high-power applications. The actively delayed time correction method to compensate distorted currents due to a relatively long resonant commutation time is newly implemented in the open loop control scheme so as to acquire the new optimum PWM pattern. Finally, the experiment of set-up in laboratory system of this converter is concretely demonstrated herein to confirm a zero current soft-switching commutation of this converter. The comparative evaluations between current-fed hard switching PWM and soft-switching PWM converters are carried out from a viewpoint of their PWM converter characteristics.

• Proceedings of the KIPE Conference
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• 2013.07a
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• pp.315-316
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• 2013

This paper presents a parameter tuning method of a LLC resonant converter for a wireless charging circuit. A switched-capacitor is used to change the resonant frequency of the resonant circuit. The simulation results verify that the efficiency of the power transfer can be improved by a duty control of the switched-capacitor for various values of the coupling coefficient.

• 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.

• Proceedings of the KIPE Conference
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• 1997.07a
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• pp.417-422
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• 1997

This paper proposed that a AC-DC Converter topology of high power factor with soft switching mode operates with four chopper connecting a number of parallel circuit. To improve these, a large number of soft switching topologies included a resonant circuit have been proposed. And, some simulative results on computer is included to confirm the validity of the analytical results. The partial resonant circuit makes use of a inductor using step up and a condenser of loss-less snubber. The result is that the switching loss is very low and the efficiency of system is high. And the snubber condenser used in partial resonant circuit makes charging engergy regenerated at input power source for resonant operation. The proposed conversion system is deemed the most suitable for high power applications where the power switching devices are used.

• Proceedings of the KIPE Conference
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• 2000.07a
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• pp.360-363
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• 2000

A half bridge type double resonant high frequency resonant inverter using PFM is described. This proposed inverter can reduce distribution of the switching current because of using the current of the serial resonant circuit to the input current of the parallel one. In the case of variable capacitance of the DC voltage source separated capacitor the analysis of inverter circuit has generally described by using normalized parameter and operating characteristics has been evaluated in terms of switching frequency and parameters. Based on the characteristics value a method of the circuit design is proposed. The theoretical results are in good agreement with the experimental ones. In the future this proposed circuit is considerated to be useful for induction heating and discharge lamp.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.1
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• pp.1-8
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• 2014

The conventional Three-Stage electronic ballast is stable, but Two-Stage electronic ballast has been researching because of efficiency. Three-Stage electronic ballast is consisted of PFC circuit, buck converter, and inverter circuit, but Two-stage is consisted of PFC circuit, Buck-Inverter full bridge circuit. The Buck-Inverter full bridge inverter consists of two half bridge inverters for low frequency switching, and high frequency switching. In the case of street lamp it is far from a lamp to a ballast, the conventional pulsed high voltage ignitor can not turn on the HID lamps because of reduction of ignition voltage. Therefore, it needs to do the research on a resonant ignition to turn on the HID lamps. Therefore, in the Two-Stage electronic ballast which has the resonant tank for ignition, the transient resonant current because of low frequency changing is analyzed, the novel algorithm is proposed to resuce the transient current.

• Proceedings of the KIPE Conference
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• 2001.10a
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• pp.256-260
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• 2001

This paper presents boost and buck and buck-boost DC-DC converter circuit topologies of high-frequency soft switching transition PWM chopper type DC-DC high power converters with a single auxiliary passive resonant snubber. In the proposed boost power converter circuits operating under a principle of ZCS turn-on and ZVS turn-off commutation schemes, the capacitor and inductor in the auxiliary passive resonant circuit works as the loss less resonant snubber. In addition to this, the switching voltage and current peak stresses as well as EMI and RFI noises can be basically reduced by this single passive resonant snubber. Moreover, it is proved that converter circuit topologies with a passive resonant snubber are capable of solving some problems of the conventional hard switching PWM processing based on high-ferquency pulse modulation operation principle. The simulation results of this converter are discussed as compared with the experimental ones. The effectiveness of this power converter with a single passive resonant snubber is verified by the 5kW experimental breadboad set up.

• Proceedings of the KIEE Conference
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• 2003.10b
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• pp.174-176
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• 2003

The power conversion system must be increased switching frequency in order to achieve a small size, a light weight and a low noise. This paper proposes a skillful and a concise PWM DC-DC converter employing both zero voltage and zero current high frequency switching(ZVCS) operation. The Proposal ZVCS circuit is composed with resonant circuit using active resonant condenser. And this circuit provides switches with ZVS and ZCS by quasi resonant only that switching transients appear. This operation results in reduction of stress and losses in the power devices and resonant components. Some simulation results are included to confirm the validity of the analytical results.