• Proceedings of the KIPE Conference
• /
• 2016.11a
• /
• pp.9-10
• /
• 2016

최근 급속한 산업 발달로 인하여 기존의 수 MW급 대용량 인버터가 산업용 팬, 컴프레서, 고속 철도 시스템 등 여러 분야에 사용되면서 이와 관련된 대용량 인버터 연구가 활발히 진행 중이다. 이런 대용량 인버터는 고효율과 직병렬의 구성된 전력용반도체 소자를 동시다발적으로 제어되어야하기 때문에 멀티레벨 인버터의 구조가 가장 적합하다. Cascaded H-bridge 멀티레벨 인버터는 커패시터와 다이오드를 사용하지 않고 스위치만으로 구성하며, 필터를 따로 구성하지 않아도 정현파와 유사하게 전압을 출력할 수 있다. 이로 인해 고주파 감소 및 각 셀을 직렬로 연결하여 입력전압보다 높은 출력전압을 얻을 수 있다. 또한, 스위칭 방법에 따라 동일한 Cascaded H-bridge 멀티레벨인버터 토폴로지에서도 각 THD와 온도에 따른 손실이 달라질 수 있다. Cascaded H-bridge 멀티레벨 인버터에서 이용하는 스위칭 방식은 첫 번째로 유니폴라 방식을 기본으로 한 Phase-shift가 있다. 이는 180도 위상차를 갖는 2개의 레퍼런스 파형과 위상천이가 된 캐리어 파형의 비교로 PWM (Pulse Width Modulation) 을 수행한다. 두 번째 방식으로는 Level-shift가 있다. 이는 캐리어 파형을 IPD (In-Phase Disposition) 방식으로 수직적으로 대역폭이 연속적이게 나열하여 레퍼런스 파형과 비교하는 PWM방식이다. 본 논문에서는 Phase-shift와 Level-shift 방식에 따른 Cascaded H-bridge 인버터와 NPC (Neutral Point Clamped) 인버터를 결합한 토폴로지에서의 온도에 따른 손실을 분석하고, 시뮬레이션을 통하여 비교 분석하였다.

• Proceedings of the KIPE Conference
• /
• 2016.07a
• /
• pp.91-92
• /
• 2016

본 논문에서는 1:3:9의 비대칭 입력전원을 갖는 H-bridge 모듈 3개를 직렬 결합하여 27-레벨의 단상 220V 출력전압을 생성할 수 있는 가정용 멀티레벨인버터 기반 PCS 시제품을 개발하였다. 가정용 멀티레벨인버터의 부하별 출력전압 및 출력전류, 전력변환 효율과 THD를 측정, 분석하였다.

• Proceedings of the KIPE Conference
• /
• 2000.07a
• /
• pp.321-324
• /
• 2000

멀티-레벨 인버터 구조는 크게 세 가지가 있다 NPC 구조, 플라잉 커패시터 구조, 그리고 H-bridge 단위 인버터 셀을 종속적으로 연결한 cascaded 구조가 그것이다. 이중에서 cascaded 구조는 지금까지 홀수 레벨만 존재하는 것으로 알려졌다 본 논문에서는 이것을 짝수 레벨로 확장한 새로운 구조를 제안하고 홀수 짝수 레벨 모두에 적용이 가능한 새로온 PWM 기법을 제안하고자 한다. 제안한 기법은 컴퓨터 시뮬레이션 및 실험으로 그타당성을 입증하고자 한다.

• Proceedings of the KIPE Conference
• /
• 2008.06a
• /
• pp.416-418
• /
• 2008

Cost effective and high efficiency energy recovery circuit (ERC) using an address voltage source is proposed. Different from prior ERC, the proposed circuit uses a voltage source to charge a panel and a current source to discharge the panel. As a result, it can be achieved zero voltage switching (ZVS) of switches in H-bridge inverter and zero current switching (ZCS) of switches of the ERC. Moreover, the proposed ERC can obtain high efficiency, high performance and the decrease of the cost and the size.

• Proceedings of the KIEE Conference
• /
• 2005.04a
• /
• pp.55-57
• /
• 2005

This paper deals with the analysis of bearing current in H-bridge seven level multilevel inverter fed induction motor. In the previous researches utilized electromagnetic equations to derive the parasitic capacitance or measured capacitance parameters, but we used FEM to derive parasitic capacitances and defined the equivalent circuit parameters in our strategy. Then we compared suggested method with conventional method in 60 [Hz] no load condition.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.11 no.6
• /
• pp.502-507
• /
• 2006

According to large-sized LCD, the CCFL used in backlight is getting longer and a backlight using one lamp makes a needed brightness by arranging lamp in parallel because of the limit of brightness. In this paper, the inverter to nu the large back-light in 42inch LCD TV using 20 CCFLs was designed to produce the same output on each lamp in any input condition. Supplementing the conventional high-low method driving CCFL, by adopting high-high one, the brightness variation among each lamp sides is improved. Additionally, to improve the brightness variation, the method connecting the lamp and the capacitor in series is used. The proposed system was verified by the experiment.

• Proceedings of the KIEE Conference
• /
• 1997.07f
• /
• pp.2155-2158
• /
• 1997

This paper describes the performance improvement of dc TIG (Tungsten Inert Gas) welder. The TIG welder consists of single phase full bridge IGBT inverter which incorporates the high frequency transformer, the boost converter for improving the input power factor, and the arc start system. The arc will be generated without fail even when the extension cable between the torch and the power source is 100m long. In addition, the arc start system with a short dc output voltage will generate less EMI noise than the traditional arc start system with a high frequency output voltage. To demonstrate the practical significance of the proposed methods, some simulation studies are presented.

• Proceedings of the KIEE Conference
• /
• 1994.07a
• /
• pp.502-504
• /
• 1994

This paper describes an induction heating system which is full-bridge parallels resonant inverter. This system consists of current-fed type inverter, and a parallels resonant circuit with a matching transformer. A parallels resonant scheme is employed, and operating range of the proposed circuit with operating frequency and load parameter is demonstrated from the result of steady state. Also, this equipments testing result introduces, good efficiency and reliability of the system. Finally, this paper experimental results are given.

• Proceedings of the KIPE Conference
• /
• 2007.11a
• /
• pp.43-46
• /
• 2007

In this paper, a novel new pulse power generator based on IGBT stacks is proposed for pulse power application. Proposed scheme consists of series connected 9 power stages to generate maximum 60kV output pulse and one series resonant power inverter to charge DC capacitor voltage. Each power stages are configured as 8 series connected power cells and each power cell generates up to 850VDC pulse. Finally pulse output voltage is applied using total 72 series connected IGBTs. The synchronization of gating signal is important for series operation of IGBTs. For gating signal synchronization, full bridge inverter and pulse transformer generates on-off signals of IGBT gating and specially designed gate power circuit was used. Proposed scheme has lots of advantages such as long lifecyle, compact size, flat topped pulse forming, small weight, protection for arc, high efficiency and flexibility to generate various kinds of pulse output.

• Proceedings of the KIPE Conference
• /
• 2009.11a
• /
• pp.206-208
• /
• 2009

In this paper, a systematical controller design method for a twostage grid-connected photovoltaic power conditioning system is proposed. For a pre-stage boost converter to achieve the stable operation in the entire region of solar array, the digital resistive current mode controller is used. This algorithm is very simple to implement with a digital controller and there is no power stage parameter dependency in the controller design. For a post-stage single-phase full-bridge inverter, a PI controller with a feedforward compensation for the inner current control is employed. Furthermore, in case that the operating point of the solar array under varying environmental conditions is higher than the required voltage for the inverter current control, the bypass mode for the boost converter is possible for the more efficient operation. The proposed control scheme is validated through the experiment of the prototype two-stage power conditioning system hardware with a 200W solar array.