• The Transactions of the Korean Institute of Power Electronics
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• v.18 no.4
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• pp.312-321
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• 2013

In this paper, high efficiency control method for flyback inverter with synchronous rectifier(SR) based on photovoltaic AC modules is proposed. In this control method, the operation of SR is classified according to the voltage spike across main switch SP. When the voltage spike across SP is lower than the rating voltage of SP, the operation of active clamp circuit is interrupted for reducing the switching loss of auxiliary switch. In this time, the SR is operated for soft-switching of SP. When the voltage spike across Sp is higher than the rating voltage of SP, the operation of active circuit is activated for reducing the voltage spike. The SR is operated for reducing the conduction loss of secondary output diode. Thus, a switching loss of the main switch can be reduced in low power region, and weighted-efficiency can be improved. A theoretical analysis and the design principle of the proposed method are provided. And validity is confirmed through simulation and experimental results.

• Proceedings of the KIEE Conference
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• 2001.04a
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• pp.320-323
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• 2001

A ZVZCS(Zero-Voltage and Zero-Current-Switching) Three Level DC/DC Converter is presented to secondary auxiliary circuit. The converter presented in this paper used a phase shift control with a flying capacitor in the primary side to achieve ZVS for the outer switch. A secondary auxiliary circuit, which consists of one small capacitor and two small diode, is added in the secondary to provides ZVZCS conditions to primary switches, and aids to clamp secondary rectifier voltage. The auxiliary circuit Includes neither lossy component nor addition active switch, which makes the proposed converter efficient and effective. The principle of operation, feature, and design considerations are illustrated and verified through the experiment with a 500W 50kHz prototype converter.

• Journal of Electrical Engineering and Technology
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• v.9 no.4
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• pp.1332-1342
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• 2014

This paper proposes a novel test circuit for SiC transistors. On-state resistance under practical application conditions is an important characteristic for the device reliability and conduction efficiency of SiC transistors. In order to measure the on-state resistance in practical applications, high voltage is needed, and high current is also necessary to ignite performance for the devices. A soft-switching circuit based on synchronous buck topology is developed in this paper. To provide high-voltage and high-current stresses for the devices without additional spikes and oscillations, a resonant circuit has been introduced. Using the novel circuit technology, soft-switching can be successfully realized for all the switches. Furthermore, in order to achieve accurate measurement of on-state resistance under switching operations, an active clamp circuit is employed. Operation principle and design analysis of the circuit are discussed. The dynamic measurement method is illustrated in detail. Simulation and experiments were carried out to verify the feasibility of the circuit. A special test circuit has been developed and built. Experimental results confirm that the proposed circuit gives a good insight of the devices performance in real applications.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.65 no.2
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• pp.114-121
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• 2016

This paper is Instant space vector PWM(Pulse Width Modulation)power conversion devices in switching power semiconductors from my generation to losses and switching when the voltage surge and current surge of electronic noise(EMI: Electro Magnetic Interference / RFI: Radio Frequency Interference)to effectively minimize the power soft-switching power conversion circuit topologies of auxiliary resonant DC tank for the purpose of high performance realization of the electric power conversion system by the high-speed switching of a semiconductor device(AQRDCT simultaneously : an active auxiliary resonance using auxiliary Quasi-resonant DC tank)DC link snubber switch has adopted a three-phase voltage inverter. AQRDCL proposed in this paper can reduce the effective and current peak stress of the power semiconductors of the auxiliary resonant snubber circuit compared to the conventional active-resonant DC link snubber, it is not necessary to install the clamp switch of the auxiliary resonant DC link, DC the peak current and power loss of the bus line can be reduced.

• Proceedings of the KIEE Conference
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• 1996.07a
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• pp.521-524
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• 1996

A new zero voltage and nero current switching(ZVZCS) full bridge(FB) PWM converter b proposed to improve the performance of the previously presented ZVZCS-FB-PWM converters [7,8]. By adding a secondary active clamp and controlling the clamp switch moderately, ZVS(for leading-leg switches) are ZCS(for lagging-leg switches) are achieved without nay lossy components, the reverie avalanche break down of leading-leg IGBTs[7] or the saturable reactor in the primary[8]. Many advantages including simple circuit topology, high efficiency, and low cost mate the new converter attractive for high voltage and high power(> 10 kW) applications. The principle of operation is explained and analyzed. The features and design considerations of the new converter are also illustrated and verified on an 1.8 kW, 100 kHz IGBT based experimental circuit.

• Proceedings of the KIPE Conference
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• 1997.07a
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• pp.247-250
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• 1997

A novel zero-voltage-switching(ZVS) isolated PWM converter for single stage power factor correction (PFC) is presented to improve the performance of the previously presented ZVT converter[5]. A simple clamp circuit in the primary side provides zero-voltage-switching condition to all semiconductor devices. This ZVS is achieved with minimum device voltage and current stresses. Operation principle, control strategy and features of the proposed converter are presented and verified by the experimental results from a 1.5 ㎾, 100 KHz laboratory prototype

• Journal of the Korean Institute of Telematics and Electronics B
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• v.33B no.5
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• pp.152-158
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• 1996

A novel resonant pulse control technique which generates high-quality sinusoidal output voltage from a resonant dc link inverter is presented for UPS applicatons. The proposed control technique limits resonant voltae overshoot without any passive or active clamp circuit, resulting in resonant pulses iwth uniform amplitude and high efficiency. The output voltage is controlled by the third order contorller iwth an inner loop of th efilter inductor current and the feedforward controller. Analysis and design of the proposed control technique are illustrated and verified on a 5kVA experimental unit.

• Proceedings of the KIPE Conference
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• 2005.07a
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• pp.266-268
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• 2005

A new synchronous switch controlled transient current build-up zero voltage switching (TCB-ZVS) forward converter is proposed. The proposed converter is suitable for the low-voltage and high-current applications. The features of the proposed converter are low conduction loss of magnetizing current, no additional circuit for the ZVS operation, high efficiency, high power density and low EMI noise throughout all load conditions.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.1
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• pp.86-92
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• 2009

This paper presents development of 6kw ZVS(Zero Voltage Switching) boost converter by 4-parallel operation. To realize a high capacity converter with 6 kw, 4-parallel operation of 1.5kW unit module is proposed in this paper. To meet high ratio input to output voltage, isolated type booster converter is designed. To achieve ZVS operation of 4-switches of full bridge and protect a voltage overshoot caused by switch turn-off, simple active-clamp circuit is applied to the primary side. For parallel operation of 4-modules, master-slave control method is proposed to achieve input current sharing of 4-unit converter modules accurately. For performance tests, simulation is carried out. Also, load and experimental tests of the developed booster converter, 230Vdc/6kW, are carried out under various conditions. For field tests, the developed converter is applied for boosting a battery power to high DC_link voltage for a VSI inverter which starts a micro-turbine(MT) installed in vehicle and it's performance is verified through high speed motoring a MT up to tens of thousands of rpm.

• Journal of Power Electronics
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• v.16 no.3
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• pp.894-904
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• 2016

This study examines the zero-voltage switching (ZVS) operation of an active-clamped forward converter (ACFC) with a current-doubler rectifier (CDR). The ZVS condition can be obtained with a much smaller leakage inductance compared to that of a conventional ACFC. Due to the significantly reduced leakage inductance, the design is optimized and the circulating loss is reduced. The operation of the ACFC with a CDR is analyzed, and a detailed ZVS analysis is conducted on the basis of a steady-state analysis. From the results, a design consideration for ZVS improvement is presented. Loss analyses of the converters shows that enhanced soft-switching contributes to an efficiency improvement under light-load condition. Experimental results from a 100-W (5-V/20-A) prototype verify that the ACFC with a CDR can attain ZVS across an extended load range of loads and achieve a higher efficiency than conventional ACFCs.