• Proceedings of the KIPE Conference
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• 2007.07a
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• pp.153-155
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• 2007

본 논문에서는 3상 저주파 변압기를 이용한 절연형 멀티레벨 인버터를 위한 새로운 공간 벡터 제어 방식을 제안한다. 제안된 제어 방식은 기존의 미리 계산된 표를 이용한 방식이 아닌 완전히 프로그래밍에 의한 방식으로 구현 시간은 기존 방식에 비해 늘이지 않으며, 확장성이 용의하다는 장점이 있다. 제안된 제어 방식을 공통암을 이용한 3상 IHCML 인버터에 적용하였으며, Matlab을 이용한 시뮬레이션 및 실험실 차원의 인버터 제작을 통하여 제안한 방식의 타당성을 검증 하였다.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.4
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• pp.502-509
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• 2013

It presents an efficient switching pattern, which expects a reduction of switching losses in a cascaded H-bridge PWM multilevel inverter. By the proposed switching scheme, the lower H-bridge module operates at low frequency of 60[Hz] because it assigns to transfer most load power. The upper H-bridge module operates at high frequency of PWM switching to improve THD of output voltage. The proposed switching pattern applies to cascaded H-bridge multilevel inverter with PD, APOD, bipolar, and unipolar switching methods. By computer-aided simulations, we verify the validity of the proposed switching scheme. Finally, we prove that the proposed PD and APOD switching patterns are better than those of the conventional one in efficiency.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.6
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• pp.1071-1079
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• 2007

In this paper, a novel space vector control method for isolated multi-level inverter using 3-phase low frequency transformers is proposed. This method is based on the simplification of the space-vector diagram of a five-level inverter using calculated table into fully programming method. The execution time of the proposed method is about same as that of the method using calculated table. Also, the proposed method is easily applied to other case level inverter. We applied this method into the 3-phase IHCML inverter using common arm. It makes possible to use a single DC power source due to employing low frequency transformers. In this inverter, the number of transformers could be reduced compare with an exiting 3-phase multi-level inverter using single phase transformer. In addition, this method generates very low harmonic distortion operation with nearly fundamental switching frequency. Finally, We tested multi-level inverter to clarify electric circuit and reasonableness through Matlab simulation and experiment by using prototype inverter.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.5
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• pp.101-109
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• 2009

In this paper, a new method, cascade 3 phase IHCML(Isolated H-bridge Cascade Multi-Level) inverter and a control method is proposed by using two 3-phase transformers that have respectively different transformation rates. Vector control technique in which the highest proximity vector has been used is also put into use. With this process, the switching frequency is almost identical with the output fundamental frequency, which makes less switching loss, and the switching frequency of the small volume of the H-bridge that is in charge of small power is highly controlled, which improves the quality of the output voltage.

• The Transactions of the Korean Institute of Power Electronics
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• v.12 no.2
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• pp.139-148
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• 2007

In this paper, we proposed the isolated multi-level inverter using 3-phase transformers. It makes possible to use a single DC power source due to employing low frequency transformers. In this inverter, the number of transformer could be reduced comparing with an exiting 3-phase multi-level inverter using single phase transformer. Also, using phase angle control method with switching frequency equal to output fundamental frequency, harmonics component of output voltage and switching losses can be reduced. Finally, we made a prototype inverter to clarify the proposed electric circuit and reasonableness of control signal.

• The Transactions of the Korean Institute of Power Electronics
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• v.12 no.2
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• pp.149-156
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• 2007

The number of transformer and the size of transformer in inverter using 3-phase transformer could be reduced compare with a multi-level inverter using single phase transformer. but still the 3-phase transformer inverter needs many switches. In this study, we proposed the isolated multi-level inverter using 3-phase transformers and common arm, in this paper. Also, using phase angle control method with switching frequency equal to output fundamental frequency, harmonics component of output voltage and switching loss can be reduced. Finally, We tested multi-level inverter to clarify electric circuit md reasonableness through Matlab simulation and experiment by using prototype inverter.