• Journal of Power Electronics
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• 제10권3호
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• pp.293-299
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• 2010

In this paper, a single-phase PFC (Power Factor Correction) dual boost converter based on input voltage estimation is studied for DC inverter air conditioner. It is focused on improving input power factor and power quality to satisfy the recent harmonic current regulation standards. Furthermore the input voltage estimation is introduced for price competitive products. A low cost and reasonable control system is implemented using a specified high-speed 32-bit microprocessor. Their effectiveness are verified through theoretical analysis and experiments.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2010년도 하계학술대회 논문집
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• pp.194-195
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• 2010

This paper investigates control algorithms for a doubly fed induction generator (DFIG) with back-to-back converter in medium-voltage wind power system under unbalanced grid conditions. Operation of DFIG under unbalanced grid conditions causes several problems such as overcurrent, unbalanced currents, active power pulsation and torque pulsation. Three different control algorithms to compensate for the unbalanced conditions have been investigated with respect to four performance factors; fault ride-through capability, efficiency, harmonic distortions and torque pulsation. The control algorithm having zero amplitude of negative sequence current shows the most cost-effective performance concerning fault ride-through capability and efficiency. The control algorithm for nullifying the oscillating component of the instantaneous active power generates least harmonic distortions. Combination of these two control algorithms depending on the operating requirements presents most optimized performance factors under the generalized unbalanced operating conditions.

• 조명전기설비학회논문지
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• 제12권3호
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• pp.67-73
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• 1998

본 연구에서는 기존의 정류회로가 포함하고 있는 고조파 발생과 역률저하문제를 개선하기 위한 방안으로 BPFC(Boost Power Factor Collection)방식을 사용하였다. 이 BPFC는 고역률올 구현하기 위해 가장 널리 쓰이는 방식중의 하나로서 입력전압과 거의 동둥한 지속적인 인덕터 전류를 정현파에 가까운 형태로 제어할 수 있다는 장점을 가지고 있다. 또한 BPFC는 제어방식에 의해 크게 달라질 수 었다. 본 논문에서는 순간모드선택 피크 전류제어방식과 PWM 평균전류 재어방식을 이용한 고역률 저고조파를 갖는 정류회로를 구성하여 각각에 대하여 비교분석하였다.

• 산업기술연구
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• 제32권A호
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• pp.115-118
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• 2012

Recently, there are a lot of papers in order to replace the electrolytic capacitor into the film capacitor in output of PFC(Power Factor Correction). However, the film capacitor, which has capacitance of low values, causes a large ripple voltage in output of PFC. The LED drivers are connected series in the output of PFC and affected by the magnitude of voltage ripple. In this paper, we have compared the fixed frequency method with the variable frequency for the constant-current control and propose the control method to avoid the sub-harmonic oscillation in the variable input voltage. An 80W PFC, using film capacitors instead of electrolytic capacitors, and LED driver has been built and compared the fixed frequency control method with the variable frequency control method.

• Journal of Power Electronics
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• 제13권1호
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• pp.161-169
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• 2013

This paper proposes a novel control strategy for a unified power quality conditioner (UPQC) including a series and a shunt active power filter (APF) to compensate the harmonics in both the distorted supply voltage and the nonlinear load current. In the series APF control scheme, a proportional-integral (PI) controller and a resonant controller tuned at six multiples of the fundamental frequency of the network ($6{\omega}_s$) are performed to compensate the harmonics in the distorted source. Meanwhile, a PI controller and three resonant controllers tuned at $6n{\omega}_s$(n=1, 2, 3) are designed in the shunt APF control scheme to mitigate the harmonic currents produced by nonlinear loads. The performance of the proposed UPQC is significantly improved when compared to that of the conventional control strategy thanks to the effective design of the resonant controllers. The feasibility of the proposed UPQC control scheme is validated through simulation and experimental results.

• 대한전기학회논문지
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• 제36권2호
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• pp.80-87
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• 1987

This paper describes a new approach to control the two-phase servomotor driven with microprocessor based inverter. Conventional 6-step driving system has some shortcomings such as vibration and loss caused by the harmonic voltage. An attempt has been made to eliminate the harmonic content of output waveform by PWM technique and to simplify the control system by phase control method. In realizing the phase control by PWM technique proposed by this paper, control circuit and algorithm has been suggested. The proposed method has been applied to the speed control system with PI controller to confirm the adaptation of the servo system and experimental results has been compared with the computer simulation.

• Journal of Power Electronics
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• 제15권2호
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• pp.443-454
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• 2015

This study proposes a novel one-cycle control scheme with a plug-in repetitive controller for load compensator. The novelty of this scheme lies in the combination of high dynamics and the simplicity of a one-cycle controller and good steady-state harmonic suppression ability of the repetitive controller. In addition, the proposed scheme can reduce the effect of the harmonics in phase voltage for the existence of the repetitive controller. Finally, experimental results on a three-phase, four-wire, three-level load compensator are reported to validate the effectiveness of the proposed control scheme.

• Journal of Power Electronics
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• 제18권3호
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• pp.863-870
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• 2018

The traditional power control theories for the harmonic reduction methods in multilevel inverters are found to be unreliable under unbalanced load conditions. The unreliability in harmonic mitigation is caused by voltage fluctuations, non-linear loads, the use of power switches, etc. In general, the harmonics are reduced by filters. However, such devices are an expensive way to provide a smooth and fast response to secure power systems during dynamic conditions. Hence, the Decoupled Double Synchronous Reference Frame (DDSRF) theory combined with a State Delay Controller (SDC) is proposed to achieve a harmonic reduction in power systems. The DDSRF produces a sinusoidal harmonic that is the opposite of the load harmonic. Then, it injects this harmonic into power systems, which reduces the effect of harmonics. The SDC is used to reduce the delay between the compensation time for power injection and the generation of a reference signal. The proposed technique has been simulated using MATLAB and its reliability has been verified experimentally under unbalanced conditions.

• 한국전자파학회논문지
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• 제18권8호
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• pp.873-879
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• 2007

본 논문에서는 Freescale사의 Si-LDMOSFET 4-W 소자를 이용하여 고효율 class-F 전력 증폭기를 구현하였다. Class-F 전력 증폭기를 구현하는데 있어서 모든 하모닉 성분들에 대해 원하는 임피던스를 갖도록 조정하기는 불가능하기 때문에 2차와3차 하모닉 성분만을 조율하여 회로의 간결함과 동시에 상대적으로 높은 효율을 얻을 수 있었다. 또한, 본 논문에 설계된 증폭기는 보다 정확하게 하모닉 성분을 조율하기 위해, LDMOSFET의 대신 호 등가 모델에서 가장 큰 영향을 미치는 drain-source capacitance(Cds)와 bonding inductance(Lb)를 추출하여 하모닉 조율 회로를 설계하였다 제작된 고효율 class-F 전력 증폭기의 측정 결과 drain-efficiency(DE) 65.1%, power-added-efficiency(PAE) 60.3%의 효율을 얻을 수 있었다.

• 대한전자공학회논문지TC
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• 제45권12호
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• pp.7-12
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• 2008

본 논문에서는 다중밴드 안테나 시스템을 위한 고효율 전력증폭기를 제시하였다. 하나의 LDMOSFET으로 이중대역에서 동작하는 class F 전력증폭기를 설계하였다. 전력증폭기의 동작 주파수는 각각 900 MHz와 2.14 GHz이다. 이중대역 동작을 위해 집중 소자로 구현한 Composite Right/Left-Handed(CRLH) 전송선로의 단위 셀을 이용하여 증폭기의 정합단과 고조파 조절 회로를 설계하였다. CRLH 전송선로는 임의로 이중대역 조절이 가능한 메타물질 전송선으로 사용될 수 있다. 증폭기의 정합단에 CRLH 전송선의 주파수 오프셋과 비선형 위상 기울기 특성을 이용하여 임의의 이중대역에서 CRLH 전송선의 동작을 가능하게 하였다. 높은 효율을 얻기 위해 모든 고조파 성분을 조절하는 것은 현실적으로 어려운 일이기 때문에 집중 소자로 구현된 CRLH 전송선을 이용하여 2차와 3차 고조파만을 조절하였다. 또한, 제안된 전력증폭기는 더 높은 효율을 얻기 위하여 출력 정합단 뿐만 아니라 입력 정합단에도 고조파 조절 회로를 사용하여 구현하였다.