• Proceedings of the KIPE Conference
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• 1998.11a
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• pp.39-43
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• 1998

A large number of soft switching topologies included a resonant circuit have been proposed. But these circuits increase number of switch in circuit and complicate sequence of switching operation. In this paper, the authors propose power conversion system, DC-AC inverter of high efficiency and high power factor with soft switching mode by partial resonant method. The switching devices in a proposed circuits are operated with soft switching by the partial resonant method, that is, PRS2MPC (Partial Resonant Soft Switching Mode Power Converter). 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 energy regenerated at input power source for resonant operation.

• Proceedings of the KIEE Conference
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• 1999.07f
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• pp.2715-2720
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• 1999

To prevent the short circuit of upper and lower arms of bridge type PWM converters as like a voltage source inverter and PWM AC/DC converter, the dead time is inserted in between two switching signals. As a result, unexpected errors are occurred. In this paper, a new dead time minimization method is proposed. According to the proposed method, very short time which is equal to the applied dead time or more short than it, is adopted at the time of current polarity is changing. Moreover, it can be operated with the polarity information of reference current in case of current control. With the experimental results. the varidity of proposed method is verified.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.31B no.9
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• pp.67-75
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• 1994

In this paper, we manufactured the continuum receiver system for observing the continuum waves emitted from the continuum sources with using the 14m radio-telescope. The receiving system measures the total power of the continuum sources and consists of DC-amplifier, beam-chopper system. Phase-Locked Loop(PLL) circuit, blanking circuit and its period selection circuit, V/F converter, and counter part which are capable of interfacing with the computer which is used for a data acquisition and making the radio-telescope track the source. We compared the obsevation results which use the existing DVM method with the observation results which use the continuum receiver to measure the total power of the sources. Moreover, by method of beam switching observation which uses newly installed beam chopper system. We can significantly improve the observational efficiency more than the existing position switching observation method.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.1
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• pp.77-85
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• 2009

With the advent of power semiconductor switching devices, power electronics relating to high frequency electromagnetic eddy current based induction heating technology have become more suitable and acceptable. This paper presents high-frequency induction heating cooking appliance circuit based on the zero current switching-PWM single ended push-pull(ZCS-PWM SEPP) resonant inverter added AC-DC converter. This inverter uses pulse-width-modulation(PWM) control method with active auxiliary quasi-resonant lossless inductor snubbers and a switched capacitor. To improved the transient performance, the PI controller is applied for this system. For the systematic parameter optimization of the PI controller, the gradient-based optimization algorithm is applied. The performance of optimized parameters is evaluated using simulation and experimental test. These results show that the proposed systematic optimal tuning method improve the transient performances of this system.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.892-893
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• 2008

본 논문에서는, 기존의 PAM 인버터와는 달리 저 단가 구현 및 높은 성능을 낼 수 PAM 인버터 구조에 대해 고찰한다. 배터리를 전원으로 사용하는 일반적인 인버터의 경우 초기기동 및 저속운전 영역에서는 배터리 전압으로 인해 전류 및 토크 리플이 크며, 배터리 SOC의 최소치 보다 낮은 역기전력을 갖는 전동기만을 사용할 수 있다. 이를 해결하기 위해 2-스위치 Buck-Boost 컨버터와 4-스위치 인버터로 구성된 새로운 PAM 인버터 시스템을 제안한다. 제안된 시스템은 DC 링크 가변을 통해 역기전력이 낮은 저속운전영역에서는 감압하고 반대로 역기전력이 높은 고속운전영역에서는 승압시킬 수 있어 전류 및 토크 리플을 줄일 수 있다. 마지막으로 시뮬레이션을 통하여 제안된 시스템의 적용 가능성을 검증한다.

• Proceedings of the KIPE Conference
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• 2002.07a
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• pp.551-554
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• 2002

This paper describes a new interactive inverter between a photovoltaic(PV) array and single-phase utility that avoid the bulky input (60Hz) transformer on the AC side. The interface employs a pwm boost converter on the DC side followed by a pwm current-forced single-phase rectifier for injecting the power from the PV array into the mains. The current waveform at the AC side remains sinusoidal and exactly in phase at all time. The circuit also has the advantage of requiring fewer switching device than high-frequency link system. This paper describes modeling of PV array and new system topology. Simulation results on the performance of the connection are also presented.

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.871-875
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• 1998

A DSP-based source current control for power conditioner is presented to compensate current harmonics and asymmetries of three-phase four-wire emergency generators caused by nonlinear and/or unbalanced loads. There-phase voltage type converter with split-dc-capacitor is adopted as the power circuit and a new direct source current control method is suggested, which simplifies the controller. The proposed control method shapes the generator current sinusoidally inphase with the voltage and allows the generator to supply maximum power even to single phase loads. An IGBT base lookVA prototype with the controller realized with a DSP (TMS320C32) is built and tested to verify the performance of the power conditioner.

• Journal of Power Electronics
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• v.16 no.5
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• pp.1752-1762
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• 2016

To achieve higher reliability in the modular multilevel converters (MMC) for HVDC transmission systems, the internal condition of the DC capacitors of the submodules (SM) needs to be monitored regularly. For an online estimation of the SM capacitance, a controlled AC current with double the fundamental frequency is injected into the circulating current loop of the MMC, which results in current and voltage ripples in the SM capacitors. The capacitor currents are calculated from the arm currents and their switching states. By processing these AC voltage and current components with digital filters, their capacitances are estimated by a recursive least square (RLS) algorithm. The validity of the proposed scheme has been verified by simulation results for a 300-MW, 300-kV HVDC system. In addition, its feasibility has been verified by experimental results obtained with a reduced-scale prototype. It has been shown that the estimation errors for both the simulation and experimental tests are 1.32% at maximum.

• Proceedings of the KIPE Conference
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• 2010.07a
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• pp.374-375
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• 2010

본 논문에서는 계통 연계가 가능한 새로운 교류/직류 전력변환 장치를 제안한다. 제안된 전력변환 회로는 정현파의 입력상 전류를 가지고, 양방향 전력 전달이 가능하며, 역률 제어가 가능하다는 장점으로 인하여 계통 연계형 전력변환 장치로 적합하다. 특히 제안된 전력변환 장치는 무효전력 소자의 사용을 최소화하여 시스템의 신뢰성을 증대시키고, 전기적 절연을 고주파 변압기를 통하여 얻도록 하여 시스템의 부피를 줄일 수 있다는 장점을 갖는다. 본 논문에서는 제안된 전력변환 회로의 구성 방법과 각 부분 별 동작에 대해서 기술하였으며 실험 장치를 구성하여 그 타당성을 입증하였다.

• Proceedings of the KIEE Conference
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• 2002.04a
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• pp.147-150
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• 2002

HPSL(High Pressure Sodium lamp)have attracted much attention in recent years, because they offer high luminous efficiency and very long life. Recently, AC-DC converters have been widely as power factor improvement circuits in the power conversion equipment An application of the ZVT-PWM(Zero Voltage Transition Pulse Width Modulation) boost converter, which has great advantage on miniaturization and high power density, to the power factor improvement circuit of the HPSL inverter are described to identify the power factor correction characteristics of the inverter. In this paper the series-parallel resonant inverter(electronic ballast) for driving a HPS lamp is discussed. Finally, a power factor corrector is cascaded in front of the electronic ballast. Consequently, a high power factor above 0.99 and low THD on the line current can be achieved.