• Journal of Power Electronics
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• 제11권6호
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• pp.824-836
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• 2011

A new fault-tolerant control topology for open-loop motor-drive systems with Delta-connected stator windings is introduced in this paper. This new control topology enables the operation of a three-phase induction machine as a two-phase machine fed by a three-phase inverter upon a failure in one of the motor phases. This topology utilizes the "open-Delta" configuration to independently control the current in each of the two remaining healthy phases. This new control technique leads to the alleviation of any torque pulsations resulting from the consequences of the asymmetrical conditions associated with this class of faults.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 E
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• pp.2097-2100
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• 1999

Nondestructive and destructive tests were performed the stator windings of three high voltage motors prior to the rewind. Nondestructive tests included ac current increase rate($\Delta$I), dissipation factor(${\Delta}tan{\delta}$), and maximum partial discharge(Qm) The destructive tests included breakdown at three phases with ac voltage. Flashover occurred between the connected winding of endwinding and the stator flame. In two cases creeping discharge occurred between the individual phase windings and the wedges In the stator ends. The results of destructive tests could rarely be determined the breakdown voltage.

• 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.

• Journal of Electrical Engineering and Technology
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• 제11권1호
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• pp.109-116
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• 2016

This paper proposes an analytic model for four-switch inverter (FSI)-driven wye (Y) or delta (Δ)-connected motors with a current ripple reduction algorithm. FSIs employ four switches in controlling three-phase load instead of using six switches. They have split dc-link stage, and due to this inherent structure there exists the voltage difference between upper and lower capacitors, which results in distortion of the inverter output voltage. To study characteristics of FSIs, this paper presents an advanced simulation models of FSI-driven control system for 3-phase motor that can has a wire connection either Y or Δ. In addition, this paper introduces a current ripple reduction scheme that mitigates degradation of control performance due to the voltage difference between the dc-link capacitors. The validity of the proposed method and the analytic model is verified by simulations and experiments carried out with 1-HP induction machine with Y or Δ-connection

• Journal of Advanced Marine Engineering and Technology
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• 제38권9호
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• pp.1137-1140
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• 2014

선박의 전동기에 고장이 발생하면 대개 육상에서 수리 후 본선에 다시 재설치 되고 있으나 연결 단자의 기호 표시가 지워지거나 분명치 않을 때는 결선과정에서 전동기 권선의 극성 구별이 어려워진다. 이로 인해 Y-${\delta}$ 기동의 전동기에서 한 권선의 극성을 반대로 잘못 연결하는 경우 전원 투입과 동시에 과다한 전류가 흐르면서 재차 2차 고장으로 이어질 위험이 있다. 이러한 문제와 관련하여 본 논문은 고정자의 1상 권선에 미소 직류전류를 흘릴 때 나머지 권선들에서 유도되는 과도 기전력의 특성을 토대로 아날로그 멀티테스터를 이용한 고정자 권선의 극성 판별법을 제시하고 관련 특성을 분석한다. 또한, 이 같은 방식을 실제 전동기에 적용하여 단계적인 측정과정을 통해 단자연결의 이상여부를 현장에서 용이하게 판별할 수 있는지를 확인해 보기로 한다.