• The Transactions of the Korean Institute of Power Electronics
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• v.13 no.3
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• pp.221-228
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• 2008

In the 2-phase excited BLDC motor drives using a unipolar PWM scheme, there exists, in some cases, a unwanted leakage current which flows through the anti -parallel diode in the non-excited phase leg of the inverter. In this paper the cases in which the leakage current exists and the influence of the leakage current are analyzed, and a novel unipolar PWM scheme which can eliminate the leakage current is proposed. The leakage current increases as the motor speed is increased or PWM duty is decreased, and as a result the output power of the motor is reduced considerably. The effectiveness of the proposed unipolar PWM scheme isverified through the comparative simulations and experiments.

• The Journal of the Korea institute of electronic communication sciences
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• v.5 no.2
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• pp.164-170
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• 2010

In brushless DC motor, current flow should be controlled such that only properly selected 2 out of 3 phases carry current depending on the position of rotor. In order to detect position of rotor, hole sensor, encoder, optical position-detecting sensor, and magnetic position-detecting sensor are frequently employed. These sensors not only often cause malfunction in low and high temperature but they also have disadvantage of increasing cost and size of an motor system. To reduce the cost and size and to increase the robustness of the motor system, recently researches on sensorless motor dirve are very active. This paper proposes a novel unipolar PWM switching method that can improve the control problem caused by the difficulty of detecting zero crossing point at high revolution speed by minimizing the switching noise while increasing the lifespan of the drive system.

• Journal of Electrical Engineering and Technology
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• v.12 no.5
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• pp.1835-1841
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• 2017

An improved single-phase full-bridge zero-voltage-switching inverter using a subtractive coupled magnetics is proposed in this paper. The proposed topology overcomes several drawbacks of the conventional ARCPI zero-voltage-switching inverter including two bulky capacitors which can cause problems such as the need for a protection circuit and voltage fluctuation of split capacitors. Also the proposed topology can reduce the number of devices required for ZVS through a simplified auxiliary circuit, thus achieving low cost and small volume and is applicable a modified unipolar PWM scheme. Detail mode analysis and design considerations are provided for optimal efficiency. In the end, the effectiveness and feasibility of the proposed topology are verified experimentally under various conditions.

• Journal of IKEEE
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• v.26 no.4
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• pp.584-589
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• 2022

For DC-AC power conversion from a high-voltage photovoltaic panel to a single-phase grid, the two-stage transformerless inverter with a buck-boost converter followed by a full-bridge inverter is widely used. To avoid an excessive leakage current due to the large parasitic capacitance of the photovoltaic panel, the full-bridge inverter can only adopt the bipolar PWM which results in much higher power loss compared to the unipolar PWM. In order to overcome such a poor efficiency, this paper proposes a new topology in which an IGBT and a diode for circuit isolation are added to the buck-boost converter. The proposed circuit isolation method allows the unipolar PWM in the full-bridge inverter without any increase in the leakage current so that the overall efficiency can be improved. The validity of the proposed solution is verified by computer simulation and power loss calculation.

• Proceedings of the KIPE Conference
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• 2002.07a
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• pp.115-118
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• 2002

In this paper, a current control method using adjustment of the phase advance angle is proposed. This proposed method improves the torque and speed response characteristic by minizing delay of current at high speed operation, and also make reverse motoring possible. Simulated results prove the effectiveness of the propposed method through comparison with the conventional unipolar PWM method.