• Proceedings of the KIPE Conference
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• 2016.11a
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• pp.121-122
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• 2016

본 논문은 3.3 kW급 전기자동차의 탑재형 충전기에 적용된 직렬 공진형 컨버터와 병렬 공진형 컨버터의 특성을 비교 및 분석 한다. 동일한 동작 조건으로 설계된 직렬 공진형 컨버터와 병렬 공진형 컨버터의 손실요인을 수학적으로 비교 분석하고 이를 시뮬레이션을 통하여 검증한다.

• Proceedings of the KIEE Conference
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• 1998.07f
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• pp.2067-2069
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• 1998

A prototype semiconductor switch for the command resonant charging system has been developed for a line type modulator, which charges parallel pulse forming network(PFN) up to voltage of 5 kV at repetition rates of 60 Hz. A phase controlled power supply provides charging of the 4.7 ${\mu}s$ filter capacitor bank to voltage up to 5 kV. A solid state module of series stack array of sixe matched SCRs(1.6 kV, 50 A) is used as a command charging switch to initiate the resonant charging cycle. Both resistive and RC snubber network are used across each stage of the switch assembly in order to ensure proper voltage division during both steady state and transient condition. A master trigger signal is generated to trigger circuits which are transmitted through pulse transformer to each of the 6 series switch stages. A pulse transformer is required for high voltage trigger or power isolation. This paper will discuss trigger method, protection scheme, circuit simulation, and test result.

• Journal of Electrical Engineering and Technology
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• v.10 no.1
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• pp.128-137
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• 2015

A novel parallel three-level zero voltage switching (ZVS) DC converter is presented for medium voltage applications. The proposed converter includes three sub-circuits connected in parallel with the same power switches to share load current and reduce the current stress of passive components at the output side. Thus, the size of the output chokes is reduced and the switch counts in the proposed converter are less that in the conventional parallel three-level DC/DC converter. Each sub-circuit combines one half-bridge converter and one three-level converter. The transformer secondary windings of these two converters are connected in series in order to reduce the size of output inductor. Due to the three-level circuit topology, the voltage stress of power switches is equal to $V_{in}/2$. Based on the resonant behavior by the output capacitance of power switches and the leakage inductance (or external inductance) at the transition interval, each switch can be turned on under ZVS. Finally, experiments based on a 2 kW prototype are provided to verify the performance of the proposed converter.

• Proceedings of the KIEE Conference
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• 2006.10d
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• pp.129-131
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• 2006

This paper presents a new ZVS-PWM high frequency inverter. The ZVS operation is achieved in the whole load range by using a simple auxiliary reverse blocking switch in parallel with series resonant capacitor. The operating principle and the operating characteristics of the new high frequency circuit treated here are illustrated and evaluated on the basis of simulation results. It was examined that the complete soft switching operation can be achieved even for low power setting ranges by introducing the high frequency dual duty cycle control scheme. In the proposed high frequency inverter treated here, the dual mode pulse modulation control strategy of the asymmetrical PWM in the higher power setting ranges and the lower power setting ones, the output power of this high frequency inverter could introduce in order to extend soft switching operation ranges. Dual duty cycle is used to provide a wide range of output power regulation that is important in many high frequency inverter applications. It is more suitable for induction heating applications the operation and control principle of the proposed high frequency inverter are described and verified through simulated results.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.21 no.6
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• pp.55-64
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• 2007

This paper represents characteristics and design example of series loaded LCC type high frequency resonant DC-DC converter with variable parallel capacitor in the secondary side of inductive power transformer. In this converter, ZVS(zero voltage switching) technique is applied to reduce turn-off switching losses, and the applied converter used the PFM switching pattern to control output voltage. The operating characteristics of the proposed converter is analyzed using nomalized parameter such as switching frequency and load factor with varing the secondary parallel resonant capacitor. The results of analysis show the operating characteristics and design method of the proposed converter using characteristic values. And the proposed converter can be applied for the contactless power supply with linear transfer system such as dean room facilities of semiconductor and Flat Panel Display.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.3
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• pp.409-415
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• 2008

This paper proposed a new optimal design method of the electronic ballast with stable run-up current for Metal Halide lamp during the ignition condition. In order to avoid operation in the acoustic resonance frequency band and to supply the optimal ignition current without demage of inverter switching components during the ignition period, the values of the series inductor Ls, the series capacitor Cs, and the parallel capacitor Cp were determined by analysis of characteristics of inverter transfer function depend on Lamp operating power and resistance of ignition condition and steady state operating condition. For the prototype ballast for a 400W Metal Halide Lamp, experimental results are presented in order to validate the proposed method.

• Journal of Power Electronics
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• v.17 no.4
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• pp.892-904
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• 2017

A design of a Class-E inverter with only one inductor and one capacitor is presented. It is operated at the optimal operation mode for domestic cooker. The design principle is based on the zero-voltage derivative switching (ZVDS) of the Class-E inverter with a parallel load network, which is a parallel resonant equivalent circuit. An induction load characterization is obtained from a large-signal excitation test bench, which is the key to an accurate design of the induction cooker system. Consequently, the proposed scheme provides a more systematic, simple, accurate, and feasible solution than the conventional quasi-resonant inverter analysis based on series load network methodology. The derivative of the switch voltage is zero at the turn-on transition, and its absolute value is relatively small at the turn-off transition. Switching losses and noise are reduced. The parameters of the ZVDS Class-E inverter for the domestic induction cooker must be selected properly, and details of the design of the components of this Class-E inverter need to be addressed. A 1,200 W prototype is designed and evaluated to verify the validation of the proposed topology.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.2
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• pp.497-507
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• 2010

This paper presents current unbalance improved half-bridge LLC resonant converter using the two transformers with different leakage inductances. The proposed converter resonates with the leakage inductance and magnetizing inductance of the transformer and the resonant capacitance. The converter operates in a wide load range and satisfies the zero voltage switching even under the light load. The series-parallel connected two transformers act as the transformers or the resonant inductances according to the operational modes, and the separate output filter inductance in the transformer secondary is not needed using the leakage inductance. The current unbalance of the secondary diode rectifier is improved using the different leakage inductances of the two transformers and the asymmetrical pulse-width modulation (PWM). In this paper, the operational principle of the converter is explained by the modes, and the design example for the prototype is also shown. To validate the performance of the converter, the prototype is implemented as the designed circuit parameters and the good performance of the proposed converter is shown through the experimental results

• Journal of Power Electronics
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• v.15 no.6
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• pp.1429-1437
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• 2015

A new parallel hybrid soft switching converter with low circulating current losses during the freewheeling state and a low output current ripple is presented in this paper. Two circuit modules are connected in parallel using the interleaved pulse-width modulation scheme to provide more power to the output load and to reduce the output current ripple. Each circuit module includes a three-level converter and a half-bridge converter sharing the same lagging-leg switches. A resonant capacitor is adopted on the primary side of the three-level converter to reduce the circulating current to zero in the freewheeling state. Thus, the high circulating current loss in conventional three-level converters is alleviated. A half-bridge converter is adopted to extend the ZVS range. Therefore, the lagging-leg switches can be turned on under zero voltage switching from light load to full load conditions. The secondary windings of the two converters are connected in series so that the rectified voltage is positive instead of zero during the freewheeling interval. Hence, the output inductance of the three-level converter can be reduced. The circuit configuration, operation principles and circuit characteristics are presented in detail. Experiments based on a 1920W prototype are provided to verify the effectiveness of the proposed converter.

• The Transactions of the Korean Institute of Power Electronics
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• v.18 no.2
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• pp.153-160
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• 2013

This research paper describes the development of battery charger with a variable output voltage capacity for charging the batteries used in electrical vehicles. The voltage and current accordingly is control via the buck converter that receives three phase current at primary side and fed to bridge rectifier which is comprised of full bridge converter and HFTR(High Frequency Transformer) for isolation and a square wave AC output. The transformer primary side is in series to divide certain charging current and the secondary side is comprised of six fix transformers so that they can generate certain amount of power and various output voltage through relay connection using 6 DC outputs. Moreover, all parallel connected full bridge serial resonant converter communicate together with upper(main) controller. The constructed structure is verified by conducting the test on PSIM as well as experimentally.