• The Transactions of the Korean Institute of Power Electronics
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• v.15 no.5
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• pp.376-380
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• 2010

This paper presents a circuit configuration of multilevel inverter to increase the number of output voltage levels by using conventional 5-level inverters connected in series. Most of all it can maximize the number of output voltage levels by employing input voltage sources, which have the power of five. When it synthesizes the same number of output voltage levels, the proposed inverter can save the number of switching devices compared with the conventional cascaded H-bridge cell inverter. So it can reduce the size, cost, power consumption of the system. We implemented computer-aided simulation and experiments for a 25-level inverter employing two 5-level inverters.

• The Journal of the Korea institute of electronic communication sciences
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• v.13 no.1
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• pp.61-68
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• 2018

This paper is elaborates on the pure sine wave single phase inverter of 500W level which is driven by battery. The inverter is structured to raise the battery voltage to 400V by using the push-pull topology, and by using H-bridge with the high voltage, it outputs common 220VAC. This topology is utilized to use the power semiconductor device in order to design and manufacture the inverter of 500W at input voltage rating of 12VDC. As a result, the efficiency exceeds 90% in partial sections, but on average, the efficiency is approximately 89.5%, and as for output voltage, frequency fluctuation range and THD, the result can be less than ${\pm}5%$.

• The Transactions of the Korean Institute of Power Electronics
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• v.20 no.4
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• pp.337-343
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• 2015

The multi-level inverters are highly efficient for high-power and medium-voltage AC driving applications, such as high-speed railway systems and renewable energy resources, because such inverters generate lower total harmonic distortion (THD) and electromagnetic interface (EMI). Lower switching stress occurs on switching devices compared with conventional two-level inverters. Depending on the multi-level inverter topology, the required components and number of switching devices are different, influencing the overall efficiency. Comparative studies of multi-level inverters based on loss analysis and output characteristic are necessary to apply multi-level inverters in high-power AC conversion systems. This paper proposes a theoretical loss analysis method based on piecewise linearization of characteristic curves of power semiconductor devices as well as loss analysis and output performance comparison of five-level neutral-point clamped, flying capacitor inverters, and high-level cascaded H-bridge multi-level inverters.

• Proceedings of the KIPE Conference
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• 2001.10a
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• pp.718-722
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• 2001

This paper proposes an SSSC based on multi-bridge inverters in PWM scheme. The proposed system consists of 6 H-bridge inverter modules per phase. The dynamic characteristic of proposed system was analyzed by simulation with EMTP codes, assuming that the SSSC is inserted in the 154-kV transmission line of one-machine-infinite-bus power system. The feasibility of hardware implementation was verified through experimental works with a scaled-model. The proposed system can be directly inserted in the transmission line without coupling transformers, and has flexibility in expanding the operation voltage by increasing the number of H-bridges.

• Proceedings of the KIPE Conference
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• 2005.07a
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• pp.659-662
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• 2005

In this paper, we proposed the novel hybrid multi-level inverter using combination of the output voltage of transformers to reduce the THD(Total Harmonic Distortion) and improve the waveform of output voltage. The proposed multi-level inverter used the output of transformer which is 1times, 2times, 4times of input of the transformers. So we increased the output voltage from the reduce the number of switching component and transformer. Also, we tested the proposed prototype 15-level inverter to clarify the proposed electric circuit and reasonableness of control signal for the proposed multi -level PWM inverter.

• Proceedings of the KIPE Conference
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• 2014.07a
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• pp.496-497
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• 2014

본 논문은 Cascaded H-bridge 멀티레벨 인버터의 출력 전압 레벨 수의 증가를 위한 모델과 스위칭 기법을 제안한다. 제안하는 모델은 기존의 Cascaded H-bridge 멀티레벨 인버터 구조에서 각 H-bridge 모듈의 출력단에 변압기를 연결하고, 변압기 2차측을 직렬로 연결한 모델이다. 이 구조에서 다수의 변압기의 턴비는 동일하고, 1개의 변압기 턴비만이 다른 턴비를 갖게된다. 따라서 1개의 변압기 턴비를 조절하여 출력전압의 전압 레벨수를 증가시킬 수 있다. 스위칭 방법은 기존에 멀티레벨 인버터에서 주로 사용되는 Level-shifted PWM 방식을 이용하여 간단하게 구현할 수 있다. 제안하는 모델의 검증을 위하여 시뮬레이션을 수행하여 제안하는 모델의 타당성을 확인한다.

• Proceedings of the KIPE Conference
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• 2012.07a
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• pp.59-60
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• 2012

Cascaded H-bridge 멀티레벨인버터의 스위칭 패턴을 기본파 생성을 위한 저주파 동작과 파형 개선 목적의 고주파 PWM 스위칭 패턴으로 구분하여 스위칭 손실을 감소시킬 수 있지만 입력단의 DC 독립전압원은 각 H-bridge 모듈이 담당하는 출력전압의 레벨에 따라 용량의 차이가 발생한다. 이는 각 H-Bridge 모듈 스위치의 전류 스트레스 차이를 의미하며, 이로 인해 H-bridge 모듈별 수명 차이를 발생시킨다. 본 논문에서는 용량 창이에 따른 모듈 특성 개선과 인버터 수명 문제를 해결하기 위하여 기존의 다중 반송파 정현 펄스폭 변조방식에 스와핑 스위칭 방법을 적용하여 Cascaded H-bridge 멀티레벨인버터에 적용함으로써 스위칭 손실 개선과 함께 각 H-bridge 별 담당 부하 전력을 동일하게 하여 동일 전류 정격 스위치의 사용을 가능하게 한다. 제안된 스와핑 스위칭 패턴을 PD, POD, APOD방식으로 구현하고 이론적 분석과 시뮬레이션을 통해 타당성을 검증한다.

• Proceedings of the KIPE Conference
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• 2014.11a
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• pp.21-22
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• 2014

본 논문은 5-레벨 NPC/H-브릿지 (Neutral Point Clamped/H-bridge) 인버터의 최적 제어 세트 (finite-control-set) 모델 예측 제어 (MPC: Model Predictive Control) 방법을 제안한다. NPC/H-브릿지 인버터의 출력 전류 제어 및 DC-link 커패시터 전압 균형을 유지하기 위해 출력 전류와 DC-link 커패시터 전압을 예측하고, 하나의 비용 함수 (cost function)을 통해 최적의 스위칭 상태를 출력한다. PSIM 시뮬레이션을 통해 제안된 제어 알고리즘의 검증하였다.

• Proceedings of the KIPE Conference
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• 2001.12a
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• pp.149-152
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• 2001

A Single-phase bi-directional inverter Using a diode bridge-type resonant circuit to implement ZVT(Zero Voltage Transition) switching is Presented. It is shown that the ZACE(Zero Average Current Error) algorithm based polarized ramptime current control can provide a suitable interface between diode bridge-type resonant circuit DC link and the inverter. The current control algorithm is analyzed about how to design the circuit with analyzed switch which m ZVT operation for the main power switch The simulation and experimental results would be shown to verify the proposed current algorithm, because the main power switch is turn on with ZVT and the bi-directional inverter is operated.

• Journal of international Conference on Electrical Machines and Systems
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• v.2 no.3
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• pp.321-329
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• 2013

A multilevel inverter employing a cascade transformer is proposed for a silent-discharge-tube ozone generating system. The proposed inverter consists of four full-bridge inverters and fourteen transformers which have a series-connected secondary. It can accurately control the amplitude of the output voltage; hereby, it improves a linear characteristic of the rate of ozone yielding. The power regulation characteristics and operational principle of the proposed system are explained from a practical point of view. High precision ozone generating performance of the proposed multilevel inverter is verified by computer-aided simulations and experiment results.