• Journal of Electrical Engineering and Technology
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• 제11권5호
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• pp.1274-1281
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• 2016

• 한국통신학회논문지
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• 제12권4호
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• pp.386-398
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• 1987

本 論文은 PWM(Pulse Width Modulation)인버어터의 스위칭作用에 의해서 發生하는 高周波 影響을 最小化하기 위한 Suboptimal PAWM(Pulse Amplitude Width Modulation)을 提示하였다. 本 方式은 Suboptimal PWM에서 THD(Total Harmonic Distorition)가 最小가 되는 固定點(基本波 電壓 u1=1.2)에서 하나의 스위칭패턴을 決定하였다. 그리고 電壓은 DC Link에서 DC Chopper에 의해 制御하게 하고 인버어터에서는 단지 高周波만을 制御하도록 하였다. 本 方式은 3相 誘導電動機의 VSD(Variable Speed Drive)에 適用하여 電動機의 騷音, 인버어터의 線間電壓 및 電流, 電流高周波 스펙트럼을 測定하였으며, 他 方式과 比較해 보았다. 그 結果로부터 本 方式의 妥當性을 立證할 수 있었다.

• Journal of Electrical Engineering and Technology
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• 제13권4호
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• pp.1528-1538
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• 2018

In this paper, configuration of $1-{\phi}$ seven-level boost DC-link cascade based reversing voltage multilevel inverter (BDCLCRV MLI) is proposed for uninterrupted power supply (UPS) applications. It consists of three level boost converter, level generation unit and full bridge circuit for polarity generation. When compared with conventional boost cascaded H-bridge MLI configurations, the proposed system results in reduction of DC sources, reduced power switches and gate drive requirements. Inverter switching is accomplished by providing appropriate switching angles that is generated by any optimization switching angle techniques. Here, round modulation control (RMC) method is taken as the optimization method and switching angles are derived and the same is compared with various switching angles methods i.e., equal-phase (EP) method, and half-equal-phase (HEP) method which results in improved quality of obtained AC power with lowest total harmonic distortion (THD). Reduction in DC sources and switch count makes the system more cost effective. A simulation and prototype model of $1-{\phi}$ seven-level BDCLCRV MLI system is developed and its performance is analyzed for various operating conditions.

• Journal of Electrical Engineering and Technology
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• 제10권2호
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• pp.529-538
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• 2015

Due to the high efficiency and compact mechanical structure, direct drive variable speed generators are used for power conversion in wind turbines. The wind energy conversion system (WECS) considered in this paper consists of a permanent magnet synchronous generator (PMSG), uncontrolled rectifier, dc-dc boost converter controlled with maximum power point tracking (MPPT) and adaptive hysteresis controlled voltage source inverter (VSI). For high utilization of the converter's power capability and stabilizing voltage and power flow, constant DC-link voltage is essential. Step and search MPPT algorithm which senses the rectified voltage ($V_{DC}$) alone and controls the same is used to effectively maximize the output power. The adaptive hysteresis band current control is characterized by fast dynamic response and constant switching frequency. With MPPT and adaptive hysteresis band current control in VSI, the DC link voltage is maintained constant under variable wind speeds and transient grid currents respectively.

• 전력전자학회논문지
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• 제17권3호
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• pp.213-221
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• 2012

In a PWM inverter-fed IPMSM (Interior Permanent Magnet Synchronous Motor) drive, a dead time is inserted to prevent a breakdown of switching device caused by the short-circuit of DC link. This distorts the inverter output voltage resulting in a current distortion and torque ripple. In addition to the dead time, nonlinearity exists in switching devices of the PWM inverter, which is generally dependent on operating conditions such as the temperature, DC link voltage, and current. The voltage disturbance caused by the dead time and inverter nonlinearity directly influences on the inverter output performance, and it is known to be more severe at low speed. In this paper, a new compensation scheme for the dead time and inverter nonlinearity under the parameter variation is proposed for a PWM inverter-fed IPMSM drive. The overall system is implemented using DSP TMS320F28335 and the validity of the proposed algorithm is verified through the simulation and experiments.

• Journal of Electrical Engineering and Technology
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• 제6권2호
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• pp.215-225
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• 2011

In this paper, a buck DC-DC bridge converter is used as a power factor correction (PFC) converter for feeding a voltage source inverter (VSI) based permanent magnet brushless DC motor (PMBLDCM) drive. The front end of the PFC converter is a diode bridge rectifier (DBR) fed from single phase AC mains. The PMBLDCM is used to drive the compressor of an air conditioner through a three-phase voltage source inverter (VSI) fed from a variable voltage DC link. The speed of the air conditioner is controlled to conserve energy using a new concept of voltage control at a DC link proportional to the desired speed of the PMBLDC motor. Therefore, VSI operates only as an electronic commutator of the PMBLDCM. The current of the PMBLDCM is controlled by setting the reference voltage at the DC link as a ramp. The proposed PMBLDCM drive with voltage control-based PFC converter was designed and modeled. The performance is simulated in Matlab-Simulink environment for an air conditioner compressor load driven through a 3.75 kW, 1500 rpm PMBLDC motor. To validate the effectiveness of the proposed speed control scheme, the evaluation results demonstrate improved efficiency of the complete drive with the PFC feature in a wide range of speed and input AC voltage.

• 전력전자학회논문지
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• 제21권5호
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• pp.381-387
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• 2016

Many efforts have focused on the improvement of power density and efficiency by downsizing the motor and inverter. Recently, Toyota, Honda, and GM realized that the compact-sized motor uses the hairpin structure with increased space factor. Reducing the maximum torque from high-speed technique also makes it possible to design the high-power density model. Toyota and Honda used the newly developed power semiconductor IGBT to decrease conduction loss for high-efficiency inverter. In particular, Toyota used the boost converter to increase the DC link voltage for high efficiency in low-torque high-speed region. Toyota and GM also used the double-sided cooling structure for miniaturization of inverter for high-power density.

• Journal of Power Electronics
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• 제15권6호
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• pp.1593-1600
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• 2015

This paper proposes a novel compensation algorithm of current offset error for single-phase linear compressor in home appliances. In a half-bridge inverter, current offset error may cause unbalanced DC-link voltage when the DC-link is comprised of two serially connected capacitors. To compensate the current measurement error, the synchronous reference frame transformation is used for detecting the measurement error. When an offset error occurs in the output current of the half-bridge inverter, the d-axis current has a ripple with frequency equal to the fundamental frequency. With the use of a proportional-resonant controller, the ripple component can be removed, and offset error can be compensated. The proposed compensation method can easily be implemented without much computation and additional hardware circuit. The validity of the proposed algorithm is verified through experimental results.

• 전력전자학회논문지
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• 제6권1호
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• pp.107-113
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• 2001

본 논문에서는 3-레벨 PWM 인버터식 STATCOM의 동특성 해석과 직류측 상.하단 캐패시터 전압의 분균등을 보상하기 위한 제어 시스템을 설계하여 시뮬레이션과 축소모형 실험에 의한 성능 해석에 관하여 기술하였다. STATCOM과 전력 계통을 등가회로로 표현하여 회로 방정식을 유도하고 수리모형을 도출하여 전체 회로의 동적 특성을 분석하고, 고안된 제어 시스템의 성능해석은 Marlab을 이용한 시뮬에리션과 축소모형 실험을 통해 검증하였는데, 검증결과 고안된 제어시스템은 무효전력 보상과 직류측 상.하단 캐패시터 전압의 불균등을 해소하는 우수한 성능을 갖는 것을 확인하였다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2018년도 전력전자학술대회
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• pp.290-291
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• 2018

This paper proposed design method of DC link capasitor and leakage inductance of transformer with high voltage cascaded NPC H-bridge inverter. DC link capacitor is designed based on the ripple power between input AC power and output AC power, and leakage inductance of transformer is designed based on FFT table of unipola PWM with NPC H-bridge inverter. The proposed design method is verified by simulation results of 6.6[kV], 1.2[MW] Cascaded NPC H-bridge inverter.