• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.317-319
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• 2005

In this paper, control algorithm for torque ripple compensation in DFIG wind power generation system is proposed. A simple PI controller is designed for the negative sequence voltage cancellation using negative sequence currents in the grid-side converter. As a result, the stator voltage contains only the positive sequence components and the torque pulsation of the generator is effectively compensated. Propose algorithm is confirmed with PSCAD simulation model.

• 전력전자학회논문지
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• 제19권5호
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• pp.457-462
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• 2014

Given their low cost, single rolling piston compressors (SRPC) are utilized in low-power room air-conditioning systems. The SRPC cycle is composed of one compression and discharge process per mechanical rotation. The load torque is high during the compression process of the refrigerants and low during the discharge process of the refrigerants. This load torque variation induces a speed ripple and severe vibration, which cause fatigue failures in the pipes and compressor parts, particularly under low-speed conditions. To reduce the vibration, the compressor usually operates at a high-speed range, where the rotor and piston inertia reduce the vibration. At a low speed, a predefined feed-forward load torque compensator is used to minimize the speed ripple and vibration. However, given that the load torque varies with temperature, pressure, and speed, a predefined load torque table based on one operating condition is not appropriate. This study proposes an online load torque compensator for SRPC. The proposed method utilizes the speed ripple as a load torque ripple factor. The speed ripple is transformed into a frequency domain and compensates each frequency harmonic term in an independent feed-forward manner. Experimental results are presented to verify the proposed method.

• 전기학회논문지
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• 제57권8호
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• pp.1377-1382
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• 2008

DSTATCOM(distribution static compensator) is one of the custom power devices, and protects a distribution line from unbalanced and harmonic current caused by non-linear and unbalanced loads. Researches about DSTATCOM are mainly divided two parts, one is the calculation of compensation current and the other part is the current control. Conventional researches use a LPF(low pass filter) to eliminate ripple component at the calculation of compensation current. But this method has a problem that LPF's characteristics restrict the compensation performance of instantaneous active and reactive power. This paper proposes a calculation of compensation current using state observer that can be a counterproposal of conventional methods using LPF. Improved performance of instantaneous active and reactive power compensation was shown by experiments.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2005년도 춘계학술대회 논문집
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• pp.800-805
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• 2005

In this study, control schemes are proposed for a propulsion system of 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 harmonic ripple at twice input ac line frequency, which causes a ripple in the dc link voltage so that beatless control is developed in inverter system to reduce the pulsating torque current. This system is verified by the system modelling and prototype test.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2008년도 하계종합학술대회
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• pp.537-538
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• 2008

A step-down DC-DC converter with On-chip Compensation for battery-operated portable electronic devices which are designed in 0.18um CMOS standard process. In an effort to improve low load efficiency, this paper proposes the PFM (Pulse Frequency modulation) voltage mode 1MHz switching frequency step-down DC-DC converter with on-chip compensation. Capacitor multiplier method can minimize error amplifier compensation block size by 20%. It allows the compensation block of DC-DC converter be easily integrated on a chip and occupy less layout area. But capacitor multiplier operation reduces DC-DC converter efficiency. As a result, this converter shows maximum efficiency over 87% for the output voltage of 1.8V (input voltage : 3.3V), maximum load current 500mA, and 0.14% output ripple voltage. The total core chip area is $mm^2$.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1998년도 Proceedings ICPE 98 1998 International Conference on Power Electronics
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• pp.380-385
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• 1998

This paper proposes a current control algorithm to reduce the torque ripple to commutation in unipolar PWM inverter-fed trapezoidal brushless dc motor drives. In this paper, we analyze the average voltage variation of the conducting phase due to commutation, and design a current controller to compensate for the average voltage variation. The proposed method predicts the duration of commutation to reduce the torque ripple due to over-compensation. Experimental results are presented that validate the proposed method.

• 전력전자학회논문지
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• 제6권2호
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• pp.180-190
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• 2001

본 논문에서는 브러시리스 직류 전동기(BLDCM)의 정류과정에서 발생하는 유도성 상 전류의 위상각 제어에 의한 토크 리플의 감소 방법에 대하여 연구한다. 고정자 코일에서 발생하는 유도성 전이 전류에 대한 위상지연의 크기는 전동기의 회전속도에 따라 달라지므로, 속도에 대한 보상각을 결정하고 테이블 처리에 의하여 실시간 제어한다. 실험으로, AVR 8515 마이크로 프로세서를 이용하여 위상지연을 보상하는 회로를 설계하였으며 4극 3상의 브러시리스 직류 전동기에 대하여 전동기의 모든 운전영역에서 토크 리플이 현저하게 감소함을 확인하였다.

• 대한전기학회논문지
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• 제39권11호
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• pp.1153-1162
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• 1990

The torque ripple reduction method is studied to improve the speed fluctuation of permanent magnet flat type brushless DC motors. To reduce the torque ripple, this study developed the compensation method of the 5'th harmonics component of air gap flux waveform which pass through the driving coils. 1/2 inch VTR was considered. As the result of this study, we can reduce the torque ripple and the speed fluctuation of the capstan motor about 20% then before and we can obtain not only better characteristics of wow/flutter but more useful capstan motors which can be applied in the multi-function VTRs.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• 제2B권4호
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• pp.174-182
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• 2002

This paper presents a comprehensive study on reducing commutation torque ripples generated in brushless DC motor drives with only a single do-link current sensor provided. In such drives, commutation torque ripple suppression techniques that are practically effective in low speed as well as high speed regions are scarcely found. The commutation compensation technique proposed here is based on a strategy that the current slopes of the incoming and the outgoing phases during the commutation interval can be equalized by a proper duty-ratio control. Being directly linked with deadbeat current control scheme, the proposed control method accomplishes suppression of the spikes and dips superimposed on the current and torque responses during the commutation intervals of the inverter. Effectiveness of the proposed control method is verified through simulations and experiments.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• 제2B권4호
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• pp.191-200
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• 2002

When power consumption increases, power supply must be efficient and reliable for good power quality. The studies on compensation system of power quality are processing actively. Voltage sag among of factors for power quality is generally PI dual control that voltage sag compensation is used. But this control is no more available since of 120[KHz] ripple rejection. So we proposed the control algorithm using PID control in 3-phase unbalanced power system and the series voltage compensator, when voltage sag occurs.