• Journal of information and communication convergence engineering
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• 제18권3호
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• pp.201-206
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• 2020

This paper presents a new method for controlling the current of lighting LEDs without current sensors. This method can be used as backup against LED current sensor faults. LED lighting requires a circuit with a constant current in order to maintain the same brightness when the ambient temperature changes. Therefore, we propose a new current estimation method to provide backup in case of current sensor faults based on the calculation of the inductor current. In the fabricated circuit, the average current changes from 144.03 mA to 155.97 mA when the ambient temperature changes from 0℃ to 60℃. The application of this study can enable the fabrication of a driving IC for LEDs in the form of a single chip without sensing resistors. This is expected to reduce the complexity of the peripheral circuit and enable precise feedback control.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 춘계학술대회 논문집 에너지변화시스템부문
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• pp.103-105
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• 2009

This paper presents the maximum-power control simulation for PMA-SynRM. For maximum power, the maximum torque / current control method is conducted in constant-torque range and flux-weakening control method is conducted in constant-power range. For considering the nonlinear characteristics of inductance, machine constant is determined by FEM. Finally, experiment is conducted to calculate the efficiency.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2013년도 전력전자학술대회 논문집
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• pp.104-105
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• 2013

When actual IPMSM is driving, it is difficult to figure out the correct current during the current control period due to the operation speed limit of digital signal processing. Therefore, in order to control IPMSM for electric vehicle efficiently, we should design 2D Look-up Table to find out optimal current reference corresponding to speed and torque of IPMSM. This paper explains the design method of 2D Look-up Table for optimal current control of constant torque area and constant output area of IPMSM for electric vehicle. Finally, experimental results are presented to verify the reliability of 2D Look-up Table.

• 전기학회논문지
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• 제60권4호
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• pp.771-775
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• 2011

This paper presents design process of linear induction motor in dynamic tester for catenary-current collection. To minimize length of rail for dynamic tester for catenary-current collection, accelerating performance of the linear induction motor is very important. So the design process of linear induction motor considered in this paper is different with general design process of linear induction motor, because dynamic tester has three type driving region, as accelerating region, constant speed region, and braking region. Considering accelerating performance of motor, distance and time from starting point to constant speed region were concerned for load condition of motor. Designed linear induction motor was analyzed by 2-dimensional finite element method. Using mechanical dynamics simulation with analysis result of 2-dimensional finite element method and accelerating performance of designed motor was proved.

• 전력전자학회논문지
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• 제3권4호
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• pp.382-387
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• 1998

본 논문은 신경회로망을 사용하여 PWM인버터의 스위칭주파수를 일정하게 유지시키기 위한 적응 히스테리시스 밴드 전류제어 방식을 제안하였다. 신경회로망의 지도신호로 중성점전압을 고려한 적응 히스테리시스 밴드 식을 유도하고, 이 전류제어에 적합한 신경회로망의 구조 및 학습 알고리즘을 제시하였다. 시뮬레이션을 통하여 전동기의 동작 상태에 관계없이 스위칭 주파수를 거의 일정하게 유지되며, 전류의 과도응답 특성의 우수함을 확인하였다.

• 한국통신학회논문지
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• 제21권10호
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• pp.2703-2709
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• 1996

This paper proposes an exact numerical method for analyzing a dipole antenna attached on a dielectric slab. A Green's function for an infinitesimal current filament on a dielectric slab is derived and a field integral equation is formulated using a boundary condition. The moment Method is used to solve the field integral equation to otain current distribution on the antenna. Since an asymptotic function is used to compute the impedance matrix elements, the computataion time is significantly reduced. Using the computed current distributions, the input impedances, the resonance lengths and the resonant resistances of the antennas for various values of the thichnessandthe dielectric constant of the slab are obtained. It was found that the resonant length and the resonant resistance are decrease monotonically as the dielectric constant increases, however, those are changed up-and-down as the substrate thickness increases.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.285-287
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• 2001

To obtain a high performance in a vector controlled induction machine, it is essential to know the instantaneous position of the rotor flux which depends on the rotor time constant. But the rotor time constant mainly varies due to the temperature rise in the motor winding, so real time compensating algorithm is necessary. This paper proposes that it uses short duration pulses added to the constant flux command current and then resultant torque command current produced by speed controller is utilized for the rotor resistance estimation. This method has advantages with a low computational requirement and does not require voltage sensors. The proposed method is proved by simulations.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 B
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• pp.1035-1037
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• 2001

This paper presents an improved hys- teresis current control method for three-phase PWM power inverters using 3-level comparator. Hysteresis current controller using 3-level comparator has an advantage of constant switching frequency compared with conventional hysteresis current controller. However, this method has disadvantage that the longer sampling period, the larger current error because the switching is performed without considering current error magnitude of each phase. The proposed method improves the control performance by selecting the optimum switching pattern in which the magnitudes of current errors are considered introducing space vector concept. Simulation results using Matlab/Simulink show that the proposed control method reduces current error keeping the merit of previous hysteresis current control method.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 합동 추계학술대회 논문집 정보 및 제어부문
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• pp.550-553
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• 2002

A source meter is a basic instrument to perform a measurement of DC characteristic of semiconductor devices. the source meter can be used as variable voltage source, variable current source, voltage meter, or current meter. The accuracy of the low current measurement can be improved with the compensation of leakage current and charge and discharge current. In the low current measurement, the RC time constant is extremely big, so the measurement speed is very low. In this thesis, the analysis of the behavior of the measurement current according to the RC time constant and output capacitance and the method to accelerate the measurement speed.

• 한국초전도저온공학회:학술대회논문집
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• 한국초전도저온공학회 2000년도 KIASC Conference 2000 / 2000년도 학술대회 논문집
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• pp.22-25
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• 2000

To improve the performance of high temperature superconducting current leads, variable cross-sectional area is considered. The cross-sectional area is varied as a function of current density to fix the safety factor along lead length. New integration method is devised to find optimum cross-sectional area distribution. New design of current lead has low heat leak into cryostat and less material than constant cross-sectional area leads. Conduction cooled lead is considered. The developed method is applied to Bi2223 current leads sheathed Ag-Au alloy.