• Proceedings of the KIEE Conference
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• 1994.07a
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• pp.491-494
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• 1994

The 3-level inverter is applied to the induction motor drive as the voltage type inverter for large poller one. This inverter divides the DC link voltage into the two parts and it is supplied to the inverter. The 3-level inverter can reduces the voltage between the each devices, and get more sinusoidal current waveform. This paper presents the new PWM method which can reduces the harmonics. The modulation at the inverter side is implemented using a DSP microprocessor.

• Proceedings of the KIEE Conference
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• 1994.07a
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• pp.435-437
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• 1994

Cramped resonant DC link inverter is analyzed by widely available software such as SPICE. In this paper, the model of ACRDCL which is based on converter switch function rather than actual circuit configuration is used. Power circuit is modeled by functional transfer function and the controller is based on the macro-model. Computer memory and runtime are based reduced compared to micro-model. Overall performance including control strategy and harmonic characteristics in the steady state can be analyzed easily.

• Proceedings of the KIEE Conference
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• 2008.10b
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• pp.245-246
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• 2008

This paper is proposed a high performance speed control of the Synchronous Reluctance Motor through the FNN(Fuzzy Neural-Network) based SV-PWM(Space Vector PWM). SV-PWM is controlled using FNN control. SV-PWM can be maximum used maximum dc link voltage and is excellent control method due to characteristic to reducing harmonic more than others. The hybrid combination of fuzzy control and neural network will produce a powerful representation flexibility and numerical processing capability. Simulation results are presented to show the validity of the proposed algorithm.

• Proceedings of the KIEE Conference
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• 2008.11a
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• pp.107-109
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• 2008

Cheju-Haenam HVDC transmission system start it's commercial operation since 1998. JEJU island is supplied with it's about 45% of total electric power from main land with HVDC link. In JEJU island, the demand of electric power is growing every year. With a current power supply, electric power reserve rate will be below the recommended one. For a stable power supply to JEJU island, KEPCO start a construction of #2 HVDC transmission system. This report is for introduction and understanding of #2 HVDC system which will be installed between JEJU island and main land. This report includes a specification of converter station and DC cable. KEPCO expect that this system will solve the power supply problem and maximum wind power plant capacity problem as well.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.374-375
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• 2011

This paper presents a method to determine parameters of BTB (back-to-back) converters in terms of the enhancement of interface flow margins. Interface flow margin is by definition a measure of how much active power can be transferred from the external areas to the study area with the fixed load demand, and it is mainly constrained by system voltage stability. BTB converters are controllable equipments with the active power flow through them, and its DC link in fact can divide the AC systems at the location and hence can reduce the fault current level. This paper first cals margin sensitivities at the nose point of F-V curves and formulates an optimization problem to update the BTB parameters to improve the margins. This procedure is repeated performed until the required margin enhancement is achieved.

• Proceedings of the KIPE Conference
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• 2001.12a
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• pp.149-152
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• 2001

A Single-phase bi-directional inverter Using a diode bridge-type resonant circuit to implement ZVT(Zero Voltage Transition) switching is Presented. It is shown that the ZACE(Zero Average Current Error) algorithm based polarized ramptime current control can provide a suitable interface between diode bridge-type resonant circuit DC link and the inverter. The current control algorithm is analyzed about how to design the circuit with analyzed switch which m ZVT operation for the main power switch The simulation and experimental results would be shown to verify the proposed current algorithm, because the main power switch is turn on with ZVT and the bi-directional inverter is operated.

• Proceedings of the KIPE Conference
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• 2001.12a
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• pp.171-174
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• 2001

This paper proposes a nonlinear impedance circuit composed by diodes and inductors or capacitors. This circuit needs no control circuits and switches, and the impedance .value is changed by the polarity of current or voltage. and this paper presents one of these applications to improve the input current of capacitor input diode rectifiers. The rectifier using the nonlinear impedance circuit id constructed with four diodes and four capacitors in addition to the conventional rectifiers, that is, it has eight diodes and five capacitors, including a DC link capacitor. It makes harmonic components of the input current reduce and the power factor improve. A circuit design method is shown by experimentation and confirmed simulation. It explained that compared conventional pulse width modulated (PWM) inverter with half pulse-width modulated (HPWM) inverter. Proposed HPWM inverter eliminated dead-time by lowering switching loss and holding over-shooting.

• Proceedings of the KIPE Conference
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• 2001.12a
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• pp.181-184
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• 2001

In this paper, a novel overmodulation strategy for space-vector PWM(SVPWM) inverters to utilize dc link voltage fully is presented. The proposed strategy uses the concept of SVPWM based on the zero sequence signal(offset voltage) injection principle. So, by modifying the pole voltage simply, the linear control of inverter output voltage over the whole overmodulation range can be achieved easily. The validity of the proposed strategy is confirmed by the experimental results.

• Journal of Power Electronics
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• v.8 no.1
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• pp.81-90
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• 2008

This paper presents an investigation of a voltage and frequency controller for an isolated asynchronous generator (IAG) driven. by a wind turbine and supplying 3-phase 4-wire loads to the isolated areas where a grid is not accessible. The control strategy is based on the indirect current control of the VSC (voltage source converter) using the frequency PI controller. The proposed controller consists of three single-phase IGBT (Insulated Gate Bipolar Junction Transistor) based VSC, which are connected to each phase of the IAG through three single phase transformers and a battery at their DC link. The controller has the capability of controlling reactive and active powers to regulate the magnitude and frequency of the generated voltage, harmonic elimination, load balancing and neutral current compensation. The proposed isolated system is modeled and simulated in MATLAB using Simulink and PSB (Power System Block-set) toolboxes to verify the performance of the controller.

• Journal of Power Electronics
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• v.16 no.4
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• pp.1541-1550
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• 2016

This paper presents a theoretical analysis and comparisons of active power filter (APF) and hybrid power filter (HPF) systems, given terminal constraints of harmonic compensations in nonlinear loads. Despite numerous publications for the two types of filters, the features and differences between them have not been clearly explained. This paper presents a detailed analysis of the operations of a HPF inverter along with those of passive power filters (PPFs). It also includes their effects on the power factor at the grid. In addition, a theoretical analysis and a systematic comparison between the APF and HPF systems are addressed based on system parameters such as the source voltage, output power, reactive component size, and power factor at the grid terminals. The converter kVA ratings and dc-link voltage requirements for both topologies are considered in the presented comparisons