• Proceedings of the KIEE Conference
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• 1991.07a
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• pp.568-572
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• 1991

This paper describes the three-phase inverter system for 1/2[HP] induction servo motor, using TMS370C050 single-chip microprocessor. The Power MOSFETs are used for PWM inverter circuit because of the advantages such as less harmonic losses and smaller peak current, less torque ripples and noises. Single-chip microprocessor enables the whole controller to be simple and reduced size as well as to more stable and flexible. The basic structures are shown for the power circuit, including the protection and driving circuitry, and the control loops for inverter control functions. The experimental results are given for the prototype PWM inverter system.

• Journal of Power Electronics
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• v.14 no.2
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• pp.324-340
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• 2014

Recent developments in power electronics technology have spurred interest in the use of renewable energy sources as distributed generation (DG) generators. The key component in DG generators is a grid-connected inverter that serves as an effective interface between the renewable energy source and the utility grid. The multifunctional inverter (MFI) is special type of grid-connected inverter that has elicited much attention in recent years. MFIs not only generate power for DGs but also provide increased functionality through improved power quality and voltage and reactive power support; thus, the capability of the auxiliary service for the utility grid is improved. This paper presents a comprehensive review of the various MFI system configurations for single-phase (two-wire) and three-phase (three- or four-wire) systems and control strategies for the compensation of different power quality problems. The advances in practical applications and recent research on MFIs are presented through a review of nearly 200 papers.

• Proceedings of the KIEE Conference
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• 2007.04c
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• pp.194-197
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• 2007

This paper proposes a linearization technique for the 3 level NPC type inverter, which increases the linear control range of inverter up to the 6-step inverter. The overmodulation range is divided into two modes depending on the modulation index(MI), In mode I, the reference angles are derived from the Fourier series expansion of the reference voltage corresponds to the MI. In mode II, the holding angles are also derived in the same way. Therefore, it is possible to obtain the linear control and the maximized utilization of PWM inverter output voltage.

• Proceedings of the KIPE Conference
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• 2004.07b
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• pp.625-629
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• 2004

This paper presents a systematical approach to study carrier based PWM techniques (CPWM) in diode-clamped and cascade multilevel inverters by using a proposed named multi-modulating pattern method. This method is based on the vector correlation between CPWM and the space vector PWM (SVPWM) and applicable to both multilevel inverter topologies. A CPWM technique can be described in a general mathematical equation, and obtain the same outputs similarly as of the corresponding SVPWM. Control of the fundamental voltage, vector redundancies and phase redundancies in multilevel inverter can be formulated separately in the CPWM equation. The deduced CPWM can obtain the full vector redundancy control, and fully utilize phase redundancy in a cascade inverter In this continued part, it will be deduced correlation between CPWM equations in multi-carrier system and single carrier system, present the mathematical model of voltage source inverter related to the common mode voltage and propose a general algorithm for multi-modulating modulator. The obtained theory will be demonstrated by simulation results.

• Proceedings of the KIPE Conference
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• 2008.06a
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• pp.142-144
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• 2008

The Former High Efficiency Inverter(the power restoration process) system process has advantage which is the energy reduction rather than the Former Inverter(the resistence damping process), However, under repair and remodeling, the power facilities capacity is not easy to increase that the former High Efficiency Inverter needs to increase the Power Facilities Capacity of 20~30% than the Inverter(the resistence damping process) so Therefore we are going to suggest the system which is not going to make an increase the power facilities capacity and is applicable the High Efficiency Inverter.

• Proceedings of the KIPE Conference
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• 2006.06a
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• pp.146-148
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• 2006

The aim of the paper is to design the PLS(Plasma Lighting System) driving inverter circuit with optimal efficiency. In general, it is known that the PLS driven by a pulse has a higher light-conversion efficiency. There are the Class-E type resonant inverter and the semi-bridge inverter as a circuit which can make a pulse with low duty ratio. In this paper, we analyze the losses of the above two circuits. To verify the loss analysis, the inverter circuit with 220V 380W input consumption is manufactured and tested. Throughout the experimental results, the high efficiency PLS system has confirmed.

• Journal of Power Electronics
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• v.11 no.1
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• pp.74-81
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• 2011

The cutoff frequency of the output LC filters of PWM inverters limits the control bandwidth of the converter system while it attenuates voltage ripples that are caused by inverter switching activities. For a selected cutoff frequency of an output LC filter, an infinite number of L-C combinations is possible. This paper analyses the characteristics of output LC filters for PWM inverters terms of the L-C combinations. Practical circuit conditions such as no-loads, full resistive-loads, and inductive-load conditions are considered in the analysis. This paper proposes a LC filter design method for PWM inverters considering both the voltage ynamics and he inverter stack size. An experimental PWM inverter system based on the proposed output LC lter design uideline is built and tested.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.54 no.5
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• pp.231-237
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• 2005

Many conventional multi-level inverters have detected switching faults by using the over voltage and current. However, fault detection of the switching elements is very difficult because the voltage and current due to each switching fault decrease more than the normal operation. Moreover, the dc-link unbalancing voltage causes a serious problem in the safety and reliability of system when the 3-level inverter faults occur Therefore, this paper proposes the simple fault diagnose method and the neutral-point-voltage control method that can protect the 3-level inverter system from the unbalancing voltage of the do-link capacitors when the faults of switching elements occur in the 3-level inverter that is very efficient in ac motor drives of the high voltage and high power applications. Through experiment results, the validity of the proposed method is demonstrated.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.1
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• pp.36-44
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• 2014

The conventional central photo voltaic inverters have several problems. First, shadow problem in each solar panel, and high DC voltage problem from each panel because of concentration to one central inverter. Therefore, module integrated inverter is proposed to solve these problems. The inverter should be small and cost effective. The cost and size in the inverter depend on the inductor. So the switching frequency should be increased to reduce the inductor and total size, but there is a problem in efficiency because of the losses in turn-on and turn-off. In the paper, the critical conduction mode(CRM) switching method is adopted to reduce the switching loss and interleaving method is proposed to increase the efficiency in Flyback converter. Finally, the validity of the proposed scheme is investigated with simulated and experimental results for a prototype system rated at 200W.

• The Transactions of the Korean Institute of Power Electronics
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• v.24 no.3
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• pp.147-152
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• 2019

With the recent emphasis on the importance of energy conservation, studies on high-efficiency elevator systems are being continuously conducted. Therefore, pulse width modulation converters are commonly used in traction drives on elevator systems. Wide bandgap devices have been increasingly commercialized, and their application to power conversion systems, such as renewable and energy storage system, has been gradually increasing. In this study, a SiC inverter for an elevator traction drive is investigated. In particular, an inverter is designed to minimize stray and parasitic inductance. Input and output filters are designed by considering switching frequency. The designed SiC inverter reduces volume by approximately 32% compared with that of a Si inverter, and power converter efficiency is over 98.8%.