• 전력전자학회논문지
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• 제13권4호
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• pp.319-327
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• 2008

3상의 PWM 인버터는 풍력발전설비에서 계통연계나 전력제어의 목적으로 그 수요가 급증하고 있다. 이러한 인버터는 스위칭에 의한 고조파를 저감하기 위하여 L-필터나 LCL-필터를 통하여 계통과 연결된다. LCL-필터는 L-필터에 비하여 낮은 스위칭 주파수의 고조파도 효율적으로 저감할 수 있으며 비교적 적은 인덕턴스로 만족할 만한 수준의 계통 전류를 생성한다. 하지만 LC의 추가로 인해 생기는 추가 극점이 시스템의 공진을 초래하여 안정성 문제에 영향을 미친다. 본 논문에서는 전력이론을 이용하여 설계된 LCL필터 시스템의 성능향상과 공진에 의한 안정성 문제의 개선기법을 제안한다. 시뮬레이션과 실험결과를 바탕으로 개선기법의 타당성을 보인다.

• Journal of Power Electronics
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• 제12권1호
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• pp.120-127
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• 2012

Fault diagnosis technique of electrical drives is becoming more and more important, since voltage fed converter system has become industrial standard in many applications. Many studies have been conducted an inverter fault diagnosis for induction motors. However, there are few researches about fault diagnosis of 3-phase ac/dc PWM (Pulse Width Modulation) converter compared to the dc/ ac inverter. The ac/dc converter is the opposite of dc/ac inverter at current flow. Also, inverter and converter have different current patterns under the same condition of IGBT (Insulated gate bipolar transistor) open switch fault. Therefore, it is difficult to apply intact diagnosis methods of inverter to the converter. This paper proposes modified fault detection methods for IGBT open switch fault in 3-phase ac/dc PWM converter by modifying established fault diagnostic methods for dc/ac inverters.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2003년도 춘계전력전자학술대회 논문집(1)
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• pp.23-26
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• 2003

This paper presents a novel hybrid type multilevel inverter in order to improve the waveshape of output voltage. The proposed multilevel inverter is consist of two full-bridge modules for level creation and one full-bridge module for PWM operation. The generated levels are total 11-level: 9-level by the level inverter and 2-level by the PWM inverter. The operational principles and analysis are explained and validity of the proposed system is verified through the experimental results using a prototype.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2005년도 전력전자학술대회 논문집
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• pp.647-650
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• 2005

The paper aims on an analysis for dc boost control using Z-source inverter. The modified space vector PWM method is used for controlling both the dc boost and ac output controls in the Z-source inverter. The capacitor voltage and the voltage stress of device with both the shoot-through time and modulation index are analyzed considering the zero state time of inverter. The theoretical analysis is verified with the simulation studies and experiments with 32-bit DSP.

• Journal of Power Electronics
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• 제11권3호
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• pp.285-293
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• 2011

This paper proposes two SRM driving systems using a variable dc-link voltage controlled by a single-phase inverter. Two SRM converter topologies of a half bridge type and a full bridge type are proposed according to the power circuits of an inverter. The phase current can be controlled by means of a PWM controller at the inverter, and the turn-on/off angle at the phase switches can be controlled by a position sensor at the converter in the drive system. The inverter acts as a peak-current limiter if the transient current exceeds its maximum value. SRMs using the proposed topologies maintain high efficiency due to energy regeneration after the turn-off of power switches. The operational modes of the proposed topologies are verified by simulation and experimental results.

• 대한전기학회논문지
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• 제39권7호
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• pp.680-691
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• 1990

In this paper the conventional resonant inverters are compared and a novel parallel resonant dc pulse inverter for high performance motor drive system is proposed. The design method and related equations for the novel resonant inverter are derived. Also, a current controller for the resonant inverter is proposed and compared with PI current controller of the conventional PWM inverter by analog simulation. The novel resonant inverter and the current controller are implemented to verify the suggested design principles. The analog simulation and the experimental results shown the satisfactory operation of the proposed inverter and the controller.

• 전기학회논문지P
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• 제59권4호
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• pp.345-350
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• 2010

This paper presents a Photovoltaic Generation system using a Space Vector Modulation. PWM voltage source inverter using inverter consists of complex type of electric power converter to compensate for the defect, that is solar cell cannot be developed continuously by connecting with the source of electric power for ordinary use. It can cause the effect of saving electric power, from 10 to 20[%]. Synchronous signal and control signal was processed by the 56F8323 microprocessor for stable modulation. Also, Waveforms output current and voltage of system controlled so that phase conforms and can supply electric power that stabilize by the unit power factor.

• 한국철도학회:학술대회논문집
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• 한국철도학회 1998년도 창립기념 춘계학술대회 논문집
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• pp.442-449
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• 1998

Since it is essential for traction motors to reduce size and weight to achieve given traction effort, they need high input voltage. But the lack of input voltage occurs periodically due to the characteristics of train system. Therefore traction inverters use over-modulation PWM to maximize inverter's voltage gain. On the other hand, IGBT inverters can use higher frequency twice than GTO ones, which resulted in the need for novel optimal synchronous PWM strategy. This paper suggests that linearly-compensated overmodulation/optimal synchronous PWM strategy and also the simulation results of the method for a real traction motor-intertia model are presented.

• Journal of Power Electronics
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• 제15권5호
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• pp.1217-1226
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• 2015

In a grid-connected photovoltaic (PV) system, the traditional Z-source inverter uses a low frequency transformer to ensure galvanic isolation between the grid and the PV system. In order to combine the advantages of both Z-source inverters and transformerless PV inverters, this paper presents a modified single-phase transformerless Z-source PV grid-connected inverter and a corresponding PWM strategy to eliminate the ground leakage current. By utilizing two reversed-biased diodes, the path for the leakage current is blocked during the shoot-through state. Meanwhile, by turning off an additional switch, the PV array is decoupled from the grid during the freewheeling state. In this paper, the operation principle, PWM strategy and common-mode (CM) characteristic of the modified transformerless Z-source inverter are illustrated. Furthermore, the influence of the junction capacitances of the power switches is analyzed in detail. The total losses of the main electrical components are evaluated and compared. Finally, a theoretical analysis is presented and corroborated by experimental results from a 1-kW laboratory prototype.

• 전력전자학회논문지
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• 제12권6호
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• pp.441-448
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• 2007

대화면 LCD TV (40인치 이상)에서 LCD 인버터의 가격 경쟁력을 위해 인버터 하나로 다수의 램프를 병렬 구동하면서 Two Stage System 구조인 IP(Integrated Power) Board 형태의 인버터 회로가 많이 사용되고 있다. 본 논문에서는 기존 IP Board의 인버터 구동 방식인 Pulse Width Modulation (PWM) 제어 방식을 분석하고, 문제점으로 제기되었던 Half-Bridge단 스위치의 하드 스위칭과 과도한 Circulating Energy 문제를 해결한 새로운 Pulse Count Modulation (PCM) 방식을 적용한 인버터를 제안하고 이론 및 실험적 검증을 통해 제안된 방식의 우수성을 확인하였다.