• The Transactions of the Korean Institute of Power Electronics
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• v.18 no.2
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• pp.184-191
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• 2013

In this paper, bidirectional AC-DC converter using dual half-bridge converter is proposed. A transformer leakage inductance in the dual half-bridge converter is used for making resonance with the capacitor of the voltage-doubler, which can help the switched current to be sinusoidal without extra inductive component and also the switching loss can be reduced through operation such as ZVS, ZCS. Both circuit analysis and design guideline are described, and also the feasibility for the proposed converter is shown through the hardware implementation and the experimental results.

• Proceedings of the KIEE Conference
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• 1993.11a
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• pp.129-131
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• 1993

Power conversion system of high performance requires high switching frequency power converter. In order to minimize commutation stress and switching losses, in this paper, AC-DC converter is embedded a partial resonant DC-Link circuit with the object of ZVCS(zero voltage switching and zero current switching). The partial resonant occurs just before converter switch operates. Thus, VA ratings of the elements and their dissipations due to effective series resistance (ESR) are very low. Some simulative results on computer are included to confirm the validity of the analytical results.

• 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.

• 제어로봇시스템학회:학술대회논문집
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• 1993.10a
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• pp.1219-1226
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• 1993

A buck-boost zero current switched(ZCS) series resonant AC to DC converter for the DC output voltage regulation together with high power factor is proposed. The proposed single phase AC to DC converter enables a zero current switching operation of all the power devices allowing the circuit to operate at high swtiching frequencies and high power levels. A dynamic model for this Ac to DC converter is developed and an analysis for the internal operational characteristics is explored. Based on this analysis, a switched discrete sliding mode control(SDSMC) technique is investigated and its advantages over the other types of current control techniques are discussed. With the proposed control technique, the unity power factor without a current overshoot and a wide range of output voltage can be obtained.

• Proceedings of the KIEE Conference
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• 2006.10d
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• pp.125-128
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• 2006

This paper presents a novel type soft switching PWM power frequency AC-AC converter using bidirectional active switches or single phase utility frequency AC-high frequency AC matrix converter. This converter can directly convert utility frequency AC (UFAC, 50Hz/60Hz) power to high frequency AC (HFAC) power ranging more than 20kHz up to 100kHz. A novel soft switching PWM prototype of high frequency multi-resonant PWM controlled UFAC-HFAC matrix converter using antiparallel one-chip reverse blocking IGBTs manufactured by IXYS corp. is based on the soft switching resonance with asymmetrical duty cycle PWM strategy. This single phase UFAC-HFAC matrix converter has some remarkable features as electrolytic capacitor DC busline linkless topology, unity power factor correction and sine-wave line current shaping, simple configuration with minimum circuit components, high efficiency and downsizing. This series load resonant UFAC-HFAC matrix converter, incorporating bidirectional active power switches is developed and implemented for high efficiency consumer induction heated food cooking appliances in home uses and business-uses. Its operating performances as soft switching operating ranges and high frequency effective power regulation characteristics are illustrated and discussed on the basis of simulation and experimental results.

• Journal of IKEEE
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• v.16 no.4
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• pp.335-342
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• 2012

This paper is studied on a new DCM-ZVS step up-down AC-DC converter of high performance, that is, high system efficiency and power factor correction (PFC). The switching devices in the proposed converter are operated by soft switching technique using a new quasi-resonant circuit, and are driven with discontinuous conduction mode (DCM) according to pulse width modulation (PWM). The quasi-resonant circuit uses a step up-down inductor and a loss-less snubber capacitor. The proposed converter with DCM also simplifies the requirement of control circuits and reduces the number of control components. The input AC current waveform in the proposed converter becomes a quasi-sinusoidal waveform proportional to the magnitude of input AC voltage under constant switching frequency. As a result, the proposed converter obtains low switching power loss and high efficiency, and its input power factor is nearly in unity. The validity of the analytical findings is confirmed by some computer simulation results and experimental results.

• The Transactions of the Korean Institute of Power Electronics
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• v.9 no.4
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• pp.372-380
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• 2004

This paper proposes a single-power-stage high frequency resonant AC-DC converter with high power factor using ZVS(Zero Voltage Switching), and integrates a conventional converter with two stage into single stage converter. Input power factor is possible to be improved as a high power factor because inductor for power factor correction(PFC) is connected in input and converter is operated in discontinued current mode(DCM) with constant duty cycle and variable switching frequency. The conventional converter with two stage need to add a switch in order to control a power factor, but single stage converter have a advantage that system is simple and cost is down, confidence is improved, etc. This paper described a operation principle and characteristic analysis for single stage AC-DC converter with high power factor and have evaluated characteristic values by using normalized parameter. We make a experimental equipment using MOSFET as a switching device on the basis of characteristic values obtained from characteristic evaluations and we conform a rightfulness of theoretical analysis by comparing theoretical waveforms and experimental waveforms.

• Journal of Power Electronics
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• v.19 no.5
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• pp.1099-1107
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• 2019

A soft switching converter with wide voltage range operation is investigated in this paper. A series resonant converter is implemented to achieve a high circuit efficiency with soft switching characteristics on power switches and rectifier diodes. To improve the weakness of the narrow voltage range in LLC converters, an alternating current (ac) power switch is used on the primary side to select a half-bridge or full-bridge resonant circuit to implement 4:1 voltage range operation. On the secondary-side, another ac power switch is adopted to select a full-wave rectifier or voltage-doubler rectifier to achiever an additional 2:1 output voltage range. Therefore, the proposed resonant converter has the capacity for 8:1 (320V~40V) wide output voltage operation. A single-stage hybrid resonant converter is employed in the study circuit instead of a two-stage dc converter to achiever wide voltage range operation. As a result, the study converter has better converter efficiency. The theoretical analysis and circuit characteristics are verified by experiments with a prototype circuit.

• The Transactions of the Korean Institute of Power Electronics
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• v.14 no.1
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• pp.72-81
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• 2009

This paper presents quasi-resonant type high power factor ac power supply for atmospheric pressure plasma cleaning system adopting three phase PFC boost converter and it's control method. The presented ac power supply consists of single phase H-bridge inverter, step-up transformer for generating high voltage and three phase PFC boost converter for high power factor on source utility. Unlikely to the traditional LC resonant converter, the propose one has an inductor inside only. A single resonant takes place through the inside inductor and the capacitor from the plasma load modeled into two series capacitor and one resistance. The quasi-resonant can be achieved by cutting the switching signal when the load current decrease to zero. To obtain power control ability, the propose converter controlled by two control schemes. One is the changing output pulse period scheme in the manner of PFM(Pulse Frequency Modulation) control. On the other, to provide more higher power to load, the DC rail voltage is directly controlled by the 3-phase PFC boost converter. The significant merits of the proposed converter are the uniform power providing capability for high quality plasma generation and low reactive power in AC and DC side. The proposed work is verified through digital simulation and experimental implementation.

• Proceedings of the KIPE Conference
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• 2018.07a
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• pp.434-435
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• 2018

In this paper, a single-phase single-stage three-level AC/DC converter with a wide controllable output voltage is presented. It integrates a PFC converter and a three level DC/DC converter into one. The proposed converter operates at a fixed frequency and provides a wide controllable output voltage ($200V_{dc}-430V_{dc}$) with high efficiencies over a wide load range. In addition, the input boost inductors operate in a discontinuous mode to improve the input power factor. Moreover, all the switching devices operate with ZVS, and the converter's THD is small especially at full load. The feasibility of the proposed converter is verified with experimental results of a 1.5kW prototype.