• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• 제4B권4호
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• pp.196-200
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• 2004

This paper presents a method to reduce the commutation torque ripple in a position sensorless brushless DC motor drive. To compensate the commutation torque ripple considerably, the duration of commutation must be known. The proposed method measures the duration of commutation from the terminal voltage of the motor, calculates a PWM duty ratio using the measured commutation interval to suppress the commutation torque ripple, and applies it to the calculated PWM duty ratio only during the next commutation. Experimental results show that pulsating currents and vibrations are considerably reduced when the proposed method is applied to a position sensorless brushless DC motor drive for the air-conditioner compressor.

• Journal of Electrical Engineering and Technology
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• 제12권5호
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• pp.1925-1933
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• 2017

The brushless DC motor's commutation torque ripple is caused by inconsistency in the rate of phase current change. Thus, a method that considers armature resistance is proposed to modulate phase current. The three-phase control strategy, which involves the "open-phase conduction, off-phase pulse width modulation, and maintained non-commutation phase" technique, is applied during commutation at full-speed segments of the motor. Changes in each phase current are analyzed theoretically by establishing mathematical model based on phase current to determine the relative difference among shutdown phase, duty, and motor operating parameters. The turn-on and turn-off phase current change rates are made to be consistent to ensure less non-commutation phase current ripple, then the torque ripple is inhibited. The simulation results show that the phase commutation current and torque ripple coefficient of the proposed method are reduced from 56.9% and 55.5% to 6.8% and 6.1%, respectively. In the experiment system, the pulsation coefficient of the motor phase current is reduced from 40.0% to 16.7% at low speed and 50.0% to 18.8% at high speed. The simulation and experimental results show that the proposed control method significantly inhibits commutation current and torque in the full section.

• 산업기술연구
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• 제24권A호
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• pp.109-117
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• 2004

This paper presents a current control strategy to reduce torque ripple of Brushless DC Motor in commutation period with PWM pattern. The torque ripple is mainly caused by the inequality in the rate of change between rising current and decaying one during commutation. And also it is influenced by the shape of real back EMF. Therefore, in the proposed control strategy, considering real back EMF a compensation voltage is generated to equalize the rate of change in these commutating currents. And then, by providing the compensation voltage in commutation period with PWM pattern, the torque ripple can be reduced. The simulation and experimental results verify that the proposed method can reduce the torque and the current ripples significantly.

• 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.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 B
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• pp.1087-1089
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• 2003

This paper presents a method to reduce commutation torque ripple in a sensorless brushless DC motor drive without current sensors. To compensate the commutation torque ripple completely, the duration of commutation must be known. The proposed method measures the duration of commutation from terminal voltage waveforms, calculates a PWM duty ratio to suppress the commutation torque ripple from the output of speed controller, and applies the calculated PWM duty ratio only during the commutation. Experimental results show that vibrations are considerably reduced when the proposed method is applied to the sensorless brushless DC moter drive for air-conditioner compressor.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1992년도 하계학술대회 논문집 B
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• pp.685-688
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• 1992

This paper studies the commutation phenomenon in the Brushless DC Motor with the trapezoidal BEMF waveform. It is shown that the torque ripple am the speed ripple due to the phase commutation depend on driving sytem, operating speed am load condition. The effects of resistance and BEMF flat width on torque ripple are considered. Speed - torque characteristics of the motor is presented considering the phase commutation. Uncommutating current control method can attenuate the torque ripple in the low speed region, and also minimize the switching loss am switching frequency. In this paper, the commutation phenomena are verified by analytical formulation and simulation.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1998년도 전력전자학술대회 논문집
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• pp.337-341
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• 1998

Brushless DC motors have trapezoidal back emf waveform. Generally, because it is drived by a voltage source inverter, the ideal rectangular phase current is not available and therefore produce torque ripple. In this paper, the torque ripple due to commutation is analysed and the practical method that can reduce the torque ripple is proposed. Simulation and experimental results show the effectiveness of the proposed method.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1998년도 전력전자학술대회 논문집
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• pp.342-346
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• 1998

The brushless DC motor with trapezoidal back emfs has torque ripple due to phase commutation. The torque ripple generates noise and vibration and cause errors in position control so this makes the brushless DC motor less suitable for high performance servo applications. In this paper, we propose a new current control method to reduce the torque ripple due to commutation, when the unipolar PWM method is applied for the phase current control of brushless DC motor.

• 전력전자학회논문지
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• 제9권3호
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• pp.195-202
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• 2004

본 연구에서는 Brushless DC Motor의 전환구간에서 토크리플 저감을 위한 전류제어 기법을 제안하였다. 전환구간에서 토크리플은 증가하는 전류의 변화율과 감소하는 전류의 변화율이 같지 않음에 주원인이 있고, 실제 역기전력의 모양에 의해서도 영향을 받는다. 이에 제안된 제어기법은 전환하는 전류들의 변화율을 같게 하는 실제 역기전력이 고려된 보상전압을 추하고, 전환구간동안에만 보상전압을 인가함으로써 토크리플을 줄이는 것이다. 시뮬레이션과 실험 결과는 제안된 방법이 토크와 전류의 리플을 현저히 줄일 수 있음을 보여준다.

• 전력전자학회논문지
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• 제22권5호
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• pp.449-456
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• 2017

This study proposes a method for compensating for the commutation torque ripple of delta-connected brushless DC motors with low inductance based on a current predictions. At the commutation instant, a phase current at the next sampling period is predicted and compared with the reference phase current to determine whether torque ripples will occur or not. If the predicted current cannot reach the reference phase current, the reference current is modified and the relevant voltage reference is produced to reduce the torque ripple. The validity of the proposed method has been verified by simulation and experimental results. The commutation torque ripple has been decreased by 17.7% at 1,000 rpm and 80% load conditions.