• Proceedings of the KIPE Conference
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• 2011.07a
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• pp.406-407
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• 2011

The dc link voltage in a single-phase PV system has necessarily twice component of fundamental wave. It makes high THD in the grid current, and according to the problem, power quality is lower. This paper proposes the new method for removing ripple voltage. The performance was verified through computer simulation using MATLAB.

• Journal of Power Electronics
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• v.15 no.6
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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.

• The Transactions of the Korean Institute of Power Electronics
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• v.23 no.2
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• pp.121-128
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• 2018

This work proposes a simple control method of a buck-type active power decoupling circuit that can minimize the ripple values in the dc link voltage. The proposed method utilizes a simplified duty calculation method and an optimal compensation gain tracking algorithm with variable-step approach. Thus, the dc link voltage ripple can be effectively reduced through the proposed method along with rapid response in tracking the optimum compensation gain. Moreover, the proposed method has better dynamic responses in the load fluctuation or abnormal situation. MATLAB/Simulink simulation and hardware-in-the-loop-simulation(HILS)-based experimental results are presented to validate the effectiveness of the proposed control method.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1343-1345
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• 2005

In this paper, control schemes are proposed for a propulsion system(Converter/Inverter) of the TTX(Tilting Train express). In developed traction converter, unity power factor control, compensation method of dc link voltage have been applied. Output current of converter contains harmonics ripple at twice input ac line frequency, which causes a ripple in the dc link voltage so that control scheme is developed in inverter system to reduce the pulsating torque current. At low speed region, vector control scheme is applied and slip frequency control is adopted at high speed region. The performance of propulsion system will be verified by simulation and prototype experimental results.

• The Transactions of the Korean Institute of Power Electronics
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• v.25 no.4
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• pp.279-285
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• 2020

An open-end winding (OEW) permanent magnet synchronous motor with dual inverters can synthesize large voltages for a motor with the same DC link voltage. This ability has the advantage of reducing the use of DC/DC boost converters or high voltage batteries. However, zero-sequence voltage (ZSV), which is caused by the difference in the combined voltage between the primary and secondary inverters, can generate a zero-sequence current (ZSC) that increases system losses. Among the methods for eliminating this phenomenon, combining voltage vector eliminated ZSV cannot be accomplished by the conventional Pulse Width Modulation(PWM) method. In this study, a PWM carrier generation method using functionalization to generate a switching pattern to suppress ZSC is proposed and applied to analyze the control influence of the center-zero vector in the switching sequence about the current ripple.

• The Transactions of the Korean Institute of Power Electronics
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• v.17 no.3
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• pp.266-273
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• 2012

In this paper, the new open fault detection and tolerant operation method for 3 phase PWM rectifier is proposed. When open fault occurred on the inverter switches of 3 Phase PWM rectifier, the DC link voltage ripple is increased because the input current of the faulty phase is distorted. In this case, the quality of electric power would decrease, and the life time of DC link capacitor is decreased. The open fault is detected by a simple MRAS(Model Reference Adaptive System) without additional hardware sensors, and the tolerant operation carried out by turning on the opposite switch of the faulty switch without any redundancy. By the proposed method, the faulty phase input current can be controlled, so that 3-phase input current is balanced relatively under the faulty condition and the voltage ripple of DC link output is reduced. The validity of the proposed technique is proved on the 6kW 3-phase PWM rectifier system by simulation and experiment.

• Proceedings of the KIPE Conference
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• 2015.07a
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• pp.315-316
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• 2015

본 논문에서는 3-레벨 Neutral-Point-Clamped (NPC) 인버터의 DC-Link 중성점 전압 리플을 저감하여 인버터 출력 전압의 품질 신뢰성 향상이 가능한 새로운 Discontinuous Pulse Width Modulation (DPWM) 기법을 제안한다. NPC 인버터에서는 두 개의 커패시터로 이루어진 DC-Link 구조로 인해 상, 하단 DC-Link 커패시터 전압 불평형인 상황에서 DC-Link 중 성점 전압 리플이 발생한다. 중성점 전압 리플 발생 시 출력 전압의 품질을 보장할 수 없으며, 민감한 부하에 손상을 입힐 수 있다. 제안한 DPWM 알고리즘은 DC-Link 커패시터 전압을 조정하는 두 개의 오프셋을 사용하여 중성점 전압 리플을 저감한다. 또한, 시뮬레이션을 통해 본 논문에서 제안한 알고리즘의 타당성을 검증한다.

• Proceedings of the KIPE Conference
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• 2008.06a
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• pp.348-350
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• 2008

A link voltage adjustment converter employing load power estimator for notebook computer adaptor is proposed. It is consisted of the boost converter as a power factor correction stage and the LLC resonant converter as a DC/DC conversion stage with a newly introduced link voltage adjustment method employing load power estimator, which helps to reduce the transformer size and peak of output voltage ripple, maintaining high efficiency over all the load condition. Experimental results with 85W converter are given to verify the validity of the proposed circuit.

• Proceedings of the KIPE Conference
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• 2018.07a
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• pp.186-188
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• 2018

In this paper, a single-phase multifunctional onboard battery charger with small DC-link capacitors is proposed, where the low-voltage battery charger is utilized as an active power filter to mitigate the inherent second-order ripple power when the high-voltage (HV) battery is charged from the grid. In this scheme, the large DC-link electrolytic capacitors of the HV battery charger can be eliminated without additional switches, leading to the reduction of cost and volume of the onboard battery charger. The validity of the proposed topology has been verified by the simulation results.

• Proceedings of the KIPE Conference
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• 2001.07a
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• pp.594-599
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• 2001

A study of single-stage PFC electronic ballast with constant do-link voltage is presented in this paper. The proposed ballast is combined by two interleaved boost cells and a conventional half bridge dc/ac inverter, By exploiting the interleaving technique, the Input ripple current of the electronic ballast is reduced. Theoretical analysis and experimental results for two 45(W) fluorescent lamps are presented.