• Journal of Power Electronics
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• 제17권6호
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• pp.1490-1499
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• 2017

The modular multilevel converter (MMC) is generally considered to be a promising topology for medium-voltage and high-voltage applications. However, in order to apply it to high-power applications, a huge number of switching devices is essential. The numerous switching devices lead to considerable switching losses, high cost and a larger heat sink for each of the switching device. In order to reduce the switching losses of a MMC, this paper analyzes the performance of the conventional discontinuous pulse-width modulation (DPWM) method and its efficiency. In addition, it proposes a modified novel DPWM method for advanced switching losses reduction. The novel DPWM scheme includes an additional rotation method for voltage-balancing and power distribution among sub modules (SMs). Simulation and experimental results verify the effectiveness and performance of the proposed modulation method in terms of its switching losses reduction capability.

• International Journal of Fuzzy Logic and Intelligent Systems
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• 제15권3호
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• pp.200-207
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• 2015

This paper proposes an active damping control method for a grid-side converter that has an LCL grid filter in the back-to-back converter. To remove the resonant frequency components produced by the LCL filter, it is necessary to measure the grid current. To do this, sensors must be added. However, it is not necessary to add sensors because the grid current is estimated by designing a suboptimal observer. In order to remove the nonlinearity and to gain fast response of control, both feedback linearization and sliding mode control are applied. The proposed method is verified through a simulation.

• Journal of Magnetics
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• 제18권1호
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• pp.50-56
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• 2013

In this paper, the 6-switch inverter for the Flux-Reversal Motor (FRM) has been presented and compared to the 4-switch inverter for the FRM, which is more popular in cost effective applications. To analyze the FRM, we adopted the two-dimensional time-stepped voltage source finite element method (FEM) that uses the actual pulse width modulation (PWM) voltage waveforms as the input data. As the FRM characteristic analysis of actual pwm voltage input, the torque ripples and iron losses (eddy current and hysteresis loss) of the FRM can be precisely calculated. With the simulated and experimental results, the performance and limitations of the 4-switch FRM which is the cost effective drive compared to the 6-switch FRM drive are provided in more detail.

• 전력전자학회논문지
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• 제26권4호
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• pp.263-270
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• 2021

Active AC/DC converters with PWM operation are utilized to regulate rectified DC bus voltage of a permanent magnet synchronous generator in the maritime DC power system. A DC bus voltage regulation strategy that exploits the six-step operation is proposed in this study. Compared with that of the PWM operation, switching loss of the converter can be significantly reduced under the six-step operation. Moreover, conduction loss can also be reduced due to the high modulation index and reduced flux-weakening current of the six-step operation. A controller is used for the proposed DC bus voltage regulation strategy to verify its validity with the simulation and experimental setup. The simulation and the experimental test results showed that the converter loss reduces to a maximum of 70% and 19%, respectively.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1998년도 Proceedings ICPE 98 1998 International Conference on Power Electronics
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• pp.701-708
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• 1998

This paper presents a novel non-resonant PWM DC-DC converter for X-ray high-voltage power generator using the parasitic impedances of the high-voltage high-frequency link transformer with its output high-voltage control scheme and steady-state characteristics compared to the conventional series-parallel resonant DC-DC converter. The key point of this approach is to evaluate effectiveness of reduction of the turn ratio of the high-voltage high-frequency transformer on improvements in power conversion efficiency and the power factor applying a boost AC-DC converter as DC voltage source, especially in the long exposure term and light output load ranges.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.143-145
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• 2006

This paper presents an overall control algorithm for a grid-connected wind-power generation system using a DFIG(doubly-fed induction generator) fed by back-to-back PWM converters. The control of DFIG is based on a stator-flux oriented vector control. The system enables not only fast and smooth synchronization but also high performance regulation of active and reactive power. Experimental results shows The feasibility of the control algorithm.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2000년도 전력전자학술대회 논문집
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• pp.645-650
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• 2000

this paper deals with HVDC Light(High Voltage Direct Current) system using space vector PWM(SVPWM) method. Because the system of this paper has d-q control scheme for HVDC Light system. HVDC Light system represented in this paper is capable of controlling active and reactive power independently. For this system. V-I curve and control methods are proposed. Also this paper describes the design of a digital system for applications in power converters such as those that would be used in the next generation of HVDC system. Finally HVDC system is implemented using DSP TMS320C31

• 전력전자학회:학술대회논문집
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• 전력전자학회 2011년도 전력전자학술대회
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• pp.370-371
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• 2011

This paper presents a control algorithm that minimizes the DC-link capacitance by decreasing the capacitor current. The capacitor current can be nullified by a feedback compensation term which is calculated from the power balance in the AC/DC converter. As a result, voltage variation in the DC-link is reduced further, which makes a large reduction in the size of DC-link capacitors which are expensive and have limitations in life time. Simulations are performed with two 80uF DC-link capacitors, which can be replaced by film capacitors.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1999년도 전력전자학술대회 논문집
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• pp.469-471
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• 1999

In this paper, the method of Space-Vector Pulse Width Modulation(SVPWM) with Fuzzy Logic Regulator(FLR) is proposed. In a conventional SVPWM, the procedures of phase transformation and choosing PWM patterns are complex. So, it should be implemented with high performance processor like Digital Signal Processor(DSP). In order to reduce a calculation burden, a proposed system adopts FLR. Using a linguistic contro strategy based on expert knowledge, FLR relieves the processor from a heavy computations. In simulations, the proposed system is validated.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 학술대회 논문집 전문대학교육위원
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• pp.84-87
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• 2004

The Attractive features of the proposed converter has lower number of power devices and also has full regenerative capability, freewheeling in chopping or PWM mode, simple control strategy and faster demagnetization during commutation. The dump component energy requirements are much lower in this converter topology than another C-dump converters. As a result, The proposed converter has improved efficiency in the overall system than Modified C-dump converter, this thesis was approved its superiority by simulation and experimental results.