• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.1
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• pp.78-84
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• 2011

In this paper, the switching frequency and THD for the reduction instead of traditional single phase inverter using a new type of central arm of the single phase inverter is proposed. The proposed single phase inverter topology, the existing one to add a arm by two-way central switch 3-level output voltage can be raised and, central arm, especially one or two of the switches by using a switch to the diode current switching algorithm was simplified. During the dead time because of this, depending on the direction of the current level does not appear in any other existing level compared to the inverter output voltage level of the THD has the advantage that less can be. The simulation and experimental results verified the validity of the proposed topology.

• Journal of Power Electronics
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• v.2 no.1
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• pp.1-10
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• 2002

An advanced active power filter for the compensation of instantaneous harmonic current components in nonlinear current load is presented in this paper. A novel signal processing technique using an adaptive neural network algorithm is applied for the detection of harmonic components generated by three-phase nonlinear current loads and this method can efficiently determine the instantaneous harmonic components in real time. The control strategy of the switching signals to compensate current harmonics of the three-phase inverter is also discussed and its switching signals are generated with the space voltage vector modulation scheme. The validity of this active filtering processing system to compensate current harmonics is substantiated on the basis of simulation results.

• Journal of Power Electronics
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• v.3 no.3
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• pp.175-184
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• 2003

In this paper, a new control scheme of Class-E inverter for reducing the crest factor of electronic ballasts for fluorescent lamps using Pulse-Frequency-Modulation (PFM) is Introduced The lifetime of the lamps is guaranteed by decreasing the lamp crest factor and also voltage stress of the switch is significantly decreased by a new scheme although conventional Class-E Inverter is used In this paper. The proposed PFM control scheme didn't use any auxiliary circuit. The proposed control strategy is executed by feeding back the Input voltage, and the zero-voltage-switching (ZVS) is ensured by maintaining constant turn-off time of the switch Therefore, the control principles of proposed method are explained in detail and its validity is verified through several simulations and experimental results.

• The Transactions of the Korean Institute of Power Electronics
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• v.20 no.6
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• pp.509-516
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• 2015

The overmodulation characteristics of a carrier-based medium vector pulse width modulation (CBMVPWM) are examined in this study. CBMVPWM can completely eliminate leakage currents in a three-phase, three-level inverter using only the switching states with the same common mode voltage even in an overmodulation operation. The analytic equations for the magnitude of the output voltage and the switching frequency are derived for overmodulation operation, and the effect of dead time on the leakage current is demonstrated. This study presents the operating principle of CBMVPWM, basic overmodulation features, and simulations and experiments for operating verification.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.502-504
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• 2009

We demonstrate a pixel-isolated bistable twist-splay namatic (PI-BTSN) liquid crystal (LC) cell which has two stable states of splay and ${\pi}$-twist. Each state is stabilized by a multi-dimensional anchoring effect of pixel-isolating polymer walls without any chiral additives. Polymer walls are formed around the pixel region by anisotropic phase separation between LCs and reactive mesogens. Switching between the two states is archived by using vertical and horizontal electric fields. The memory mode of the fabricated LC cell has shown infinity memory time.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.31 no.11
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• pp.125-132
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• 1982

This paper analyzes the transient control characteristics of power system by dynamic braking. This method, one type of network switching, employs the injection of controllable shunt resistors at or near the generator bus after the disturbances. First, the power system is simulated mathematically for applying the dynamic braking. And the electrical transient control characteristics are considered by controlling the brake size and insertion time. Second, the mechanical torque of turbine-generator is calculted for the mechanical characteristics. This analysis results show that the electrical characteristics are improved but the turbine-generator shaft is impacted by brake switching. However, these problems can be solved by controlling the brake dynamically.

• The Transactions of the Korean Institute of Power Electronics
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• v.25 no.5
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• pp.404-411
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• 2020

Inductive power transfer (IPT) systems for electric vehicles generally require zero phase angle (ZPA) frequency tracking control to achieve high efficiency. Current sensors are used for ZPA frequency tracking control. However, the use of current sensors causes several problems, such as switching noise, degrading control performance, and control complexity. To solve these problems, this study proposes ZPA frequency tracking control without current sensors. Such control enables ZPA frequency tracking without real-time control and achieves stable zero voltage switching operation closed to ZPA frequency within all coupling coefficient and load ranges. The validity of the proposed control algorithm is verified on LCCL-S topology with a 3.3 kW rating IPT experimental test bed. Simulation verification is also performed.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.1071-1073
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• 2000

The use of HDL(Hardware Description Language) is now central to the ASIC(Application Specific Integrated Circuit). HDL-based ASIC can simplify the process of development and has a competition in market because it reduce the consuming time for the design of IC(Integrated circuit) in system level. Therefore, the development of power electronics system on chip (SOC), to design microcontroller and switching logic as one chip, is required extremely for the purpose of having reliability and low cost in power electronics which is based on switching elements. The major application of SOC is variable converter, active filter inverter for induction motor. UPS and power supply with a view to reducing electro-magnetic pollution.

• Journal of IKEEE
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• v.14 no.2
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• pp.9-15
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• 2010

In this study, we have been proposed the new type of a transcranial magnetic stimulation adopted a variable voltage capacitor with Cockcroft-Walton circuit and constant-frequency current resonant half-bridge inverter. This a transcranial magnetic stimulation has some merits compared with the conventional one. First, it doesn't require the high voltage transformer. And second, it has less switching losses, compact size and capability in adjusting the transcranial magnetic stimulation output energy precisely. In this paper, we have performed the output characteristics of a transcranial magnetic stimulation system which is well known as magnetic stimulation. The tested results are described as a function of pulse repetition rate and switching numbers of the half-bridge inverter.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.11
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• pp.2109-2118
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• 2011

The power system has to maintain its synchronism from transient disturbances and oscillations. To achieve this, the static var compensator(SVC), which is a flexible AC transmission system(FACTS), is applied to the power system. SVC using an advanced control algorithm improves the stability of power system. This paper is a study on design of SVC to improve harmonics and power factor of power plant. The proposed SVC analyzes harmonics, voltage drop and reactive power in real time. On the basis of the analysis of the data, the SVC using a switching control algorithm decreases harmonic signals and increases the power factor. The experimental results show that the proposed SVC enhances the stability of power system.