• The Transactions of the Korean Institute of Power Electronics
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• v.17 no.3
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• pp.238-245
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• 2012

This paper presents a sensorless speed control of a 2-phase switch reluctance motor(SRM). The proposed sensorless control scheme is based on the slide mode observer with parameter compensator to improve the estimation performance. In the stand still position, the initial rotor position is determined by pulse current responses of each phase windings and the current difference. In order to determine an accurate initial rotor position, the two initial rotor positions are estimated by the difference of the pulse currents. From the stand still to the operating region, a simple open loop control which determines the commutation sequence by the pulse current of the unexcited phase winding is used. When the motor speed is reached to the sensorless control region, the estimated rotor position and speed by the slide mode observer are used to control the SRM. The flux calculator used in the slide mode observer is designed by phase voltage and the voltage drops in the phase resistance of the winding. The accuracy of the flux calculator is dependent on the phase resistance. For the continuous update of the phase resistance, current gradient at the inductance break point is used in this paper. The error of the estimated rotor position at the current gradient position is used to update the phase resistance to improve the sensorless scheme. The proposed sensorless speed control scheme is verified with a practical compressor used in home appliances. And the results show the effectiveness of the proposed control scheme.

• The Transactions of the Korean Institute of Power Electronics
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• v.11 no.4
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• pp.293-301
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• 2006

This paper proposes a control algorithm for STATic synchronous COMpensator(STATCOM), based on Space Vector Modulation(SVM) and Hysteresis Current Controller(HCC) techniques. STATCOM is used to reactive power compensation on a distribution network. The proposed algorithm utilizes the advantages of the fast dynamic response of the hysteresis current control and the reduced switching number of the SVM scheme. The controller determines a set of space vectors from a region detector and applies a space vector. A set of space vectors including the zero vector, to reduce the number of switching, is determined from output signals of two hysteresis comparators. The presented control system was tested with digital simulation in the Borland C++ program and demonstrate the advantage of the proposed hysteresis current controller.

• Proceedings of the KIPE Conference
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• 2011.11a
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• pp.63-64
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• 2011

The inevitable calculation time delay of digital controller especially degrades the voltage control performance of three-phase UPS systems. This paper proposes time delay compensators based on the Smith-predictor for both voltage and current controllers of three-level NPC inverters. The PSIM-based simulation results show that the proposed controller with delay compensator gives improved voltage control performance with respect to time delay.

• Proceedings of the KIPE Conference
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• 1997.07a
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• pp.269-275
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• 1997

This paper presents real time digital signal processor(DSP) control of UPS system feeding processor(DSP) control of UPS system feeding nonlinear loads to provide sinusoidal inverter output voltage. The control scheme is composed of an rms voltage compensator, the load current harmonics feed-forward loop for the cancellation of output voltage harmonics, and the output voltage harmonics feedback loop for system stability. The controller employs a Texas Instruments TMS320C40GFL50 DSP.

• Proceedings of the KIPE Conference
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• 2016.11a
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• pp.29-30
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• 2016

This paper describes a distributed static series compensator (DSSC) which is a type of distributed flexible ac transmission system (DFACTS). The control principles including the power flow control and the current regulation are explained in detail. In order to verify the effectiveness of the DSSC, the simulation results are offered.

• Journal of Power Electronics
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• v.17 no.3
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• pp.798-810
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• 2017

This paper presents a combined system of a small-capacity inverter and multigroup delta-connected thyristor switched capacitors (TSCs). The system is referred to as a hybrid static compensator (HSC) and has the functions of dynamic reactive power compensation and harmonic suppression. In the proposed topology, the load reactive power is mainly compensated by the TSCs. Meanwhile the inverter is meant to cooperate with TSCs to achieve continuous reactive power compensation, and to filter the harmonics generated by nonlinear loads and the TSCs. First, the structure and mathematical model of the HSC are discussed Then the control method of the HSC is presented. An improved reduced order generalized integrator (ROGI)-based selective current control method is adopted in the inverter to achieve high-performance reactive and harmonic current compensation. Meanwhile, a switch control strategy is proposed to implement precise and fast switching of the TSCs and to avoid changing the time delay needed by the conventional switch strategy. Experiments are implemented on a 20 KVA HSC prototype and the obtained results verify the validity of the proposed HSC system.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.21 no.8
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• pp.151-159
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• 2007

This paper proposes a improved decoupling current control algorithms using a compensator to enhance the robustness to the stator inductance error. And the compensator composed from a d-axis current error for sensing change of the real stator inductance can match the estated stator inductance to the real stator inductance. A great advantage of this algorithms is more robust than feedforward decoupling current control or dynamic decoupling control. So it looks suitable to the practical applications where the exact parameters are unknown. Though simulation and experimental results with 1[kW] prototype PMSM and TMS320F2812 board for motor control, we show that the proposed controller achieves the desired performance.

• The Transactions of the Korean Institute of Power Electronics
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• v.17 no.5
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• pp.409-415
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• 2012

This paper presents a new software-based on-line dead-time compensation technique for a single-phase grid-connected photovoltaic (PV) inverter system. To prevent a short circuit in the inverter arms, a switching delay time must be inserted in the pulse width modulation (PWM) signals. This causes the dead-time effect, which degrades the system performance around zero-crossing point of the output current. To reduce the dead-time effect around the zero-crossing point of grid current, a harmonic mitigation of grid current is used as an additional part of the synchronous frame current control scheme. This additional task mitigates the harmonic components caused by the dead-time from the grid current. Simulation and experimental results are shown to verify the effectiveness of the proposed dead-time compensation method in the single-phase grid-connected inverter system.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.8
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• pp.1353-1359
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• 2010

This paper presents the determination of synchronous compensator(S.C) rating and parameter in Cheju AC network. The role of S.C is to supply Inertia and reactive power to HVDC system which is a kind of a generator without the function of reactive power control and Inertia. Therefore, the parameters of S,C have to be determined by considering HVDC operating characteristics. The background of this paper is the determination of S.C parameters in Cheju AC network in the case of replacing current operating S,C to new S.C type.

• Proceedings of the KIEE Conference
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• 1988.11a
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• pp.287-289
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• 1988

A reactive power compensator whiych employs a 3-phase voltage source PWM converter is presented and ana lysed in this study. In this study, instantaneous reactive power compensator by the theort of instantaneous real and imaginary power are theoretically studied how to compensate reactive power occured by fundamental and harmonic reactive current. And we showed the compensation characteristic as well as the capacity of condenser.