• Journal of Power Electronics
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• 제15권5호
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• pp.1149-1157
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• 2015

As a key part in the wind turbine system, the power electronic converter is proven to have high failure rates. At the same time, the failure of the wind power converter is becoming more unacceptable because of the quick growth in capacity, remote locations to reach, and strong impact to the power grid. As a result, the correct assessment of reliable performance for power electronics is a crucial and emerging need; the assessment is essential for design improvement, as well as for the extension of converter lifetime and reduction of energy cost. Unfortunately, there still exists a lack of suitable physic-of-failure based evaluation tools for a reliability assessment in power electronics. In this paper, an advanced tool structure which can acquire various reliability metrics of wind power converter is proposed. The tool is based on failure mechanisms in critical components of the system and mission profiles in wind turbines. Potential methodologies, challenges, and technology trends involved in this tool structure are also discussed. Finally, a simplified version of the tool is demonstrated on a wind power converter based on Double Fed Induction Generator system. With the proposed tool structure, more detailed information of reliability performances in a wind power converter can be obtained before the converter can actually fail in the field and many potential research topics can also be initiated.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
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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 Power Electronics
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• 제16권6호
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• pp.2005-2015
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• 2016

A high-step-up DC/DC converter for renewable energy systems is proposed. The proposed structure provides high voltage gain by using a coupled inductor without the need for high duty cycles and high turn ratios. The voltage gain is increased through capacitor-charging techniques. In the proposed converter, the energy of the leakage inductors of the coupled inductor is reused. This feature reduces the stress on the switch. Therefore, a switch with low ON-state resistance can be used in the proposed converter to reduce losses and increase efficiency. The main switch is placed in series with the source. Therefore, the converter can control the energy flow from the source to the load. The operating principle is discussed in detail, and a steady state analysis of the proposed converter is conducted. The performance of the proposed converter is verified by experimental results.

• Journal of Power Electronics
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• 제15권2호
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• pp.356-365
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• 2015

This paper presents a new single phase front-end ac-dc bridgeless power factor correction (PFC) rectifier topology. The proposed converter achieves a high efficiency over a wide range of input and output voltages, a high power factor, low line current harmonics and both step up and step down voltage conversions. This topology is based on a non-inverting buck-boost (Zeta) converter. In this approach, the input diode bridge is removed and a maximum of one diode conducts in a complete switching period. This reduces the conduction losses and the thermal stresses on the switches when compare to existing PFC topologies. Inherent power factor correction is achieved by operating the converter in the discontinuous conduction mode (DCM) which leads to a simplified control circuit. The characteristics of the proposed design, principles of operation, steady state operation analysis, and control structure are described in this paper. An experimental prototype has been built to demonstrate the feasibility of the new converter. Simulation and experimental results are provided to verify the improved power quality at the AC mains and the lower conduction losses of the converter.

• Journal of Power Electronics
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• 제18권4호
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• pp.1007-1014
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• 2018

A novel dual DC-DC flyback converter with leakage-energy recycling is presented in this paper. Only an active switch is used for this converter. A pulse-width-modulation strategy is adopeted to control this switch. Two transformers are employed for the proposed converter. During the switch ON-period, the primary windings of the two transformers store energies. At the switch OFF-period, the energies stored in the primary windings of the two transformers are released to the output via the secondary windings of the two transformers. Meanwhile, the leakage energies of the two transformers can be recycled. The operating principles and steady-state analyses of the proposed converter are described in detail. A prototype circuit of the proposed converter is implemented for verifying the performances.

• 전기학회논문지
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• 제65권11호
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• pp.1925-1930
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• 2016

Fuel cell power generation system, unlike conventional energy sources, converts chemical energy into electrical energy through electrochemical reaction of hydrogen and oxygen. This paper presents the control of interleaved multi-phase boost converter as the feasibility study on small-scale prototype electric railway vehicle application using fuel cell generation system. PSIM simulation program is to be used to implement the modeling of the electrical fuelcell as well as traction motor control with interleaved multi-phase boost converter. Comparing the input current ripple rate, two-phase interleaved boost converter is less than the boost converter. But the more multi-phase not less proportional to the ripple factor. we confirmed that the amplitude of the input current ripple rate of converter depend on duty ratio.

• Journal of Power Electronics
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• 제17권5호
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• pp.1127-1136
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• 2017

This paper proposes a new soft switching dual input converter for renewable energy systems. Multi-input converters are produced by combining discrete converters. These converters reduce the number of circuit elements, cost, volume and weight of the converter and provide a constant output power in different weather conditions. Furthermore, soft switching techniques can be applied to increase efficiency. In this paper, a Zero Voltage Transition (ZVT) dual input boost converter is presented. Only one auxiliary circuit is used to provide the soft switching condition for all of the semiconductor elements. The proposed converter, which is simulated by ORCAD software, is theoretically analyzed. To confirm the validity of the theoretical analysis, a prototype of proposed converter was constructed. Simulation and experimental results confirm the theoretical analysis. An efficiency comparison shows a one percent improvement at nominal loads.

• Journal of electromagnetic engineering and science
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• 제11권3호
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• pp.161-165
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• 2011

In this paper, a high-efficiency DC-AC converter is used for wireless energy transmission. The DC-AC convertter is implemented by combining the oscillator and power amplifier. Given that the conversion efficiency of a DC-AC converter is strongly affected by the efficiency of the power amplifier, a high-efficiency power amplifier is implemented using a class-E amplifier structure. Also, because of the low output power of the oscillator connected to the input stage of the power amplifier, a high-gain two-stage power amplifier using a drive amplifier is used to realize a high-output power DC-AC converter. The high-efficiency DC-AC converter is realized by connecting the oscillator to the input stage of the high-gain high-efficiency two-stage class-E power amplifier. The output power and the conversion efficiency of the DC-AC converter are 40.83 dBm and 87.32 %, respectively, at an operation frequency of 13.56 MHz.

• 전기학회논문지
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• 제66권2호
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• pp.459-467
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• 2017

An urban railway power substation consists of three thyristor dual converters. Two converters are connected to up and down trolley line to supply the electric energy or feed the regenerative energy back to the distribution. When the two converters break down, the remaining converter is used in an emergency. One thyristor dual converter system (TDCS) manages the energy of two or three railway stations. If the TDCS fails, the trains stop operating. To solve the problem, this paper proposes the three parallel operation control algorithm of thyristor dual converter system using the emergency converter. The broken TDCS can be replaced by the emergency converter in other TDCS. The effectiveness of this proposed control is verified by simulation.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1997년도 전력전자학술대회 논문집
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• pp.124-130
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• 1997

The main switch of high-frequency boost converter may be failed because the high switching current or voltage can damage this switch. The high switching stress can be reduced by snubber circuit. In this paper, a new passive snubber circuit which can recover trapped snubber energy without added control is proposed for boost converter. The control of boost converter with proposed snubber is the same as the conventional one. In addition, the energy recovery circuit can be implemented with a few passive components. The analysis for proposed circuit is presented, and the validity of the circuit is verified through simulation and experiment.