• Journal of Power Electronics
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• v.15 no.1
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• pp.190-201
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• 2015

This paper uses the switching function approach to present a simple state model of the Vienna-type rectifier. The approach introduces the relationship between the DC-link neutral point voltage and the AC side phase currents. A novel direct power control (DPC) strategy, which is based on the sliding mode control (SMC) for Vienna I rectifiers, is developed using the proposed power model in the stationary ${\alpha}-{\beta}$ reference frames. The SMC-based DPC methodology directly regulates instantaneous active and reactive powers without transforming to a synchronous rotating coordinate reference frame or a tracking phase angle of grid voltage. Moreover, the required rectifier control voltages are directly calculated by utilizing the non-linear SMC scheme. Theoretically, active and reactive power flows are controlled without ripple or cross coupling. Furthermore, the fixed-switching frequency is obtained by employing the simplified space vector modulation (SVM). SVM solves the complicated designing problem of the AC harmonic filter. The simplified SVM is based on the simplification of the space vector diagram of a three-level converter into that of a two-level converter. The dwelling time calculation and switching sequence selection are easily implemented like those in the conventional two-level rectifier. Replacing the current control loops with power control loops simplifies the system design and enhances the transient performance. The simulation models in MATLAB/Simulink and the digital signal processor-controlled 1.5 kW Vienna-type rectifier are used to verify the fast responses and robustness of the proposed control scheme.

• Journal of Power Electronics
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• v.9 no.4
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• pp.623-630
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• 2009

This paper proposes a filter design guideline for grid-connected single-phase inverters. By analyzing the instantaneous voltage applied to the filter inductor, the switching ripple current through the filter inductor can be precisely calculated. Therefore, filter inductance can be designed accurately, which guaranties that the switching ripple current will be under the target value. The proposed filter design method is verified by experiment.

• Proceedings of the KIPE Conference
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• 2018.07a
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• pp.114-116
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• 2018

This paper presents a control strategy to achieve the balanced sinusoidal output currents, as well as sinusoidal input currents for the matrix converter (MC) under unbalanced input voltages. By regulating the modulation index of the converter according to the instantaneous input voltages, the output currents are kept balanced and sinusoidal. In order to obtain sinusoidal input currents, the input power factor angle should be dynamically calculated based on the positive and negative sequence components of the input voltages. This paper proposes a simple method to construct the expected input power factor angle without the complicated sequence component extraction of input voltages. Simulation results are given to validate the effectiveness of the proposed control strategy.

• Proceedings of the KIPE Conference
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• 2008.10a
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• pp.172-174
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• 2008

The detent force of the permanent magnet linear synchronous motor (PMLSM) is caused by the interaction between the permanent magnet and the iron core of the mover without input current. It is a function of the mover position relative to the stator. This paper proposes a control based method to reduce the detent force for the PMLSM. This detent force that can be predicted by finite element method (FEM) is compensated by injecting the instantaneous current using the field oriented control (FOC) method. Both the simulated and experimental results are reported to validate the effectiveness of this proposed method.

• Proceedings of the KIEE Conference
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• summer
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• pp.351-353
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• 2004

In recent years, customers and power supplies are interested in power quality. Demands of customers are change from standard quality of distribution power system to various high quality of distribution power system. so, it is necessary to apply power quality compensator. in our project, we develop the UPQC(Unfied Power Quality Compensator of 45kVA which compensates power factor and voltage sag, interruption. it is very frequently occurred power quality $problems^{[1-3]}$ As a series and shunt compensator, UPQC consists of two inverters with common do link capacitor bank. It compensates the current quality in the shunt part and the voltage quality in the series part. In this paper, we present the design and control algorithm for 4SkVA UPQC system. As a control algorithm is implemented by digital controller, we consider sample-and-hold of signals. In this simulation, we use EMTDC/PSCAD V3.0 software which can simulate instantaneous voltage and current.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.3
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• pp.6-11
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• 2006

This paper describes the novel control techniques design of VSC(Voltage Sag Corrector) for the purpose of power line quality enhancement. A fast detecting technique of voltage sag is implemented through the detection of instantaneous value on synchronous rotating dq-reference frame. The first order digital filter is added in the detection algorithm to protect the insensitive characteristics against the noise. The relationship between the total detection time and cut-off frequency of the filter is described. The size of the capacitor bank used as the energy storage element is designed from the point of view of input/output energy with circuit analysis. Finally, the validity of the proposed scheme is proven through the simulated results.

• The Transactions of the Korean Institute of Power Electronics
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• v.9 no.2
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• pp.105-111
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• 2004

In this paper, a new self-oscillated type high voltage power supply for the OPC(Organic Photo Conductor) charge is proposed, which has variable constant current source characteristics to improve the charge characteristic of the OPC roller. The proposed control method enables high quality printing characteristics regardless of the circumstance change such as ambient temperature or humidity by changing the current reference signal. To verify the proposed control method various experiments are performed.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1489-1491
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• 2005

This paper proposes a design method using PQR instantaneous power theory on the active power filter, unbalanced nonlinear load condition and unbalanced source voltage condition in three-phase four-wire systems. For reduction of current harmonics and neutral current, the control structure including repetitive controller is proposed and controller gain is designed. For fully-digital implementation, ramp comparison PWM method was adopted. Simulation results verify good performance of the proposed current control strategy on the shunt APFs.

• The Transactions of the Korean Institute of Power Electronics
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• v.7 no.5
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• pp.472-481
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• 2002

In this paper, the instantaneous flux Is applied to control the position of the SRG (Switched Reluctance Generator) without position sensor. The position information of the rotor is required in the drive of SRG. These data are generally obtained by a shaft encoder or resolver. In some cases, the EMI(Electro Magnetic Interference), vibration, thermal, and humidity environments may cause the difficulties in maintaining the satisfactory performance for the position detection. Therefore, the elimination of the position and speed sensor is needed. In this paper, a new method for the position estimation of the SRG is proposed. The estimation of the flux is calculated by using the measured voltage and current. The rotor position gets from the flux profile. The output voltage is also controlled constantly by PR control algorithm. These methods are verified by computer simulations md experiments using DSP. Experimental results certificate that the proposed method is able to control the SRG stable, and keep the output voltage constant in spite of changing of the load.

• Proceedings of the KIPE Conference
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• 1997.07a
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• pp.182-187
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• 1997

In this paper, a instantaneous speed measurement method using a three phase sinusoidal encoder is described and it's simulations are developed. The proposed method can easily detect the AC motor speed by using that the encoder is propotion to the AC motor speed. The performance of proposed method is confirmed by computer simulation and experiment results. The high accuracy of the optimum control system, AC motor speed detection is designed and proposed.