• The Transactions of the Korean Institute of Electrical Engineers B
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• v.55 no.6
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• pp.299-305
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• 2006

In this paper, we suggest a new space vector PWM modulation method with very short processing time which does not need identification of nearest three vectors(NTV) and duty ratio for each vector. The suggested PWM method makes mean value of phase voltage to be same as reference during every modulation period by use of a triangle in small hexagon on multi-level vector space. This paper described the suggested modulation method can be successfully applied to the space vector modulation use of multi-level inverter by computer simulations and experiments.

• Proceedings of the KIPE Conference
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• 2004.07b
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• pp.620-624
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• 2004

Th is paper presents a systematical approach to study carrier based PWM techniques (CPWM) in diode-clamped and cascade multilevel inverters by using the proposed multi-modulating pattern method. This method is based on the vector correlation between CPWM and space vector PWM (SVPWM) and applicable to both multilevel inverter topologies. The CPWM technique can be described in a general mathematical equation, and obtain the same outputs similarly as of 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 a full vector redundancy control, and fully utilize phase redundancy in a cascade inverter. In the paper, CPWM equations and corresponding algorithm for generating multi-modulating signals will be performed, in which SVPWM attributes will be presented by corresponding controllable factors.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.5
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• pp.950-960
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• 2010

In this paper, a multi-input multi-output(MIMO) integral variable structure system with an integral-augmented sliding surface is designed for the improved robust control of uncertain multivariable system under the matched persistent disturbance. To effectively remove the reaching phase problems, the integral augmented sliding surface is proposed. Then for its design, the eigenstructure assignment technique is introduced to. To guarantee the designed performance against the persistent disturbance, the stabilizing control for multi-input system is also designed to generate the sliding mode on the integral sliding surface. The stability of the global system together with the existence condition of the sliding mode are investigated and proved for the case of multi input system in the presence of uncertainty and disturbance. The reaching phase is completely removed in proposed MIMO VSS by satisfying the two requirements. An example and computer simulations will be present for showing the usefulness of algorithm.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.221-221
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• 2000

The heat exchange part in a modern multi-type air-conditioning system employs multiple-pass heat exchangers. The heat-transfer performance of an each pass in such an exchanger depends strongly on the length of the two-phase region and the mass flow of the refrigerant. The total length and diameters of the pipes, the exit conditions, and the arrangement of each pass as well as the geometrical shape of the distributor at the branching sections are considered to be major factors affecting the heat-transfer performance. The refrigerant commonly used in these systems is HCFC-22. The two objectives of this paper are to investigate the characteristics of the refrigerant flow rate and the superheat in the evaporator of a multi-type air-conditioning system for a single or simultaneous operating conditions and to control the superheat and the refrigerant flow rate of the evaporator.

• Journal of the Korean Society for Railway
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• v.7 no.4
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• pp.339-344
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• 2004

This paper proposes transformerless power conversion system consisting of a single-phase diode rectifier and a shunt hybrid filter for the electric-railway system. The hybrid filter consists of a single tuned LC filter per a phase and a low-rated NPC type multi-level inverter. Compared with conventional active filters. transformers are not used. Also, LC filter works as not only a harmonic filter tuned at the 3rd harmonic frequency but also a switching-ripple filter. The rating of the active filter can be decreased by using a NPC type multi-level inverter. The simulation results confirm the validity of the system.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.10
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• pp.85-89
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• 2010

During a ground fault the maximum fault current and neutral to ground voltage will appear at the pole nearest to the fault. Distribution lines are consisted of three phase conductors, an overhead ground wire and a multi-grounded neutral line. In this paper phase to neutral faults were staged at the specified concrete pole along the distribution line and measured the ground fault current distribution in the ground fault current, three poles nearest to the fault point, overhead ground wire and neutral line. A effect by grounding resistance of poles of ground fault current in the 22.9[kV] multi-ground distribution system. by field tests.

• Korean Journal of Optics and Photonics
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• v.35 no.4
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• pp.143-149
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• 2024

We analyze the effect of atmospheric fluctuation on laser beam propagation, using a single-phase screen model and a multi-phase screen model. When a laser beam (wavelength 1064 nm, radius 10 mm, collimated by 25.4 mm optics) propagates 3 km, atmospheric fluctuation with structure constant C_n² in the range of 10^-17 to 10^-14 is generated by the single- and multi-phase screen models. The results of short-term and long-term exposures are analyzed in terms of the beam profile, power in the bucket, and beam radius at the receiver plane. The power in the bucket and beam radius increase as the structure constant increases. When the structure constant is less than 2×10^-15, the results of the single- and multi-phase screen models are similar, within a difference of 1.5 %. However, when the structure constant is greater than 2×10^-15, the difference between the two models increases, and the multi-phase screen model is appropriate under this condition.

• Proceedings of the KIPE Conference
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• 2000.07a
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• pp.355-359
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• 2000

This paper deal with the harmonic reduction technique in three-phase square-wave inverter system formed by single-phase inverter. To reduce the harmonics six single-phase inverters are used for forming multi-phase inverter and zig-zag connected output transformer for eliminating the harmonic 6(2k-1)$\pm$1 orders. And an ac filter is furnished at output side. Computer simulations show that the THD of the output voltage can be reduced immensely.

• The Transactions of the Korean Institute of Power Electronics
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• v.18 no.4
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• pp.333-341
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• 2013

In this paper, a feedback linearization control is proposed to regulate the output voltages of a three-phase four-wire inverter under the unbalanced and nonlinear load conditions. First, the nonlinear model of system including the output LC filters is derived in the d-q-0 synchronous reference frame. Then, the system is linearized by the multi-input multi-output feedback linearization. The tracking controllers for d-q-0-components of three-phase line-to-neutral load voltages are designed by linear control theory. The experimental results have shown that the proposed control method gives the good performance in response to the load conditions.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.31B no.7
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• pp.179-189
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• 1994

A two-phase neural network finds exact feasible solutions for a constrained optimization programming problem. The time-varying programming neural network is a modified steepest-gradient algorithm which solves time-varying optimization problems. In this paper, we propose a time-varying two-phase optimization neural network which incorporates the merits of the two-phase neural network and the time-varying neural network. The proposed algorithm is applied to system identification and function approximation using a multi-layer perceptron. Particularly training of a multi-layer perceptrion is regarded as a time-varying optimization problem. Our algorithm can also be applied to the case where the weights are constrained. Simulation results prove the proposed algorithm is efficient for solving various optimization problems.