• 전력전자학회:학술대회논문집
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• 전력전자학회 2003년도 추계학술대회 논문집
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• pp.230-233
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• 2003

Simulation model of induction type fixed speed wind power generator is developed. It is shown that the peak value of inrush current during start up changes according to the firing angle control strategy of soft starter. New proposed firing angle control scheme showed $25\%$ of reduction of peak current which results in smaller drop of gird voltage at the point of common coupling during start up.

• Journal of Power Electronics
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• 제17권2호
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• pp.315-322
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• 2017

LED is a promising new generation of green lighting with the advantages of high efficiency, good optical performance, long lifetime and environmental friendliness. A pulsating current can be used to drive LEDs. However, current with a high peak-to-average ratio is unfavorable for LEDs. A novel control scheme for the ac-dc critical conduction mode (CRM) flyback LED driver is proposed in this paper. By using the input voltage, output voltage and average output current to control the turn-on time of the switch, the peak-to-average ratio of the output current can be reduced. The operation principle is analyzed and an implementation circuit is put forward. Experimental results show the effectiveness of the proposed scheme.

• 전기학회논문지
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• 제65권4호
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• pp.586-592
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• 2016

The current control of Continuous Conduction Mode(CCM) can be implemented by several methods: peak current control; average current control; and hysteresis control. Among these methods, the hysteresis current control is popularly applied in various converter applications because of its simplicity of implementation, fast current control response and inherent peak current limiting capability. However, a current controller with conventional hysteresis band which multiplies the current reference has the disadvantage that the modulation frequency varies in one cycle of the input voltage and, as a result, generates high switching frequency in the low input voltage section. Also it is complicated to design the input filter due to varying switching frequency. This paper proposed an optimum hysteresis-band current control method where the band is generated by using both multiplication method and sum method to maintain the modulation frequency to be nearly constant. This approach can solve the high switching frequency in the low input voltage section, and achieve easy design of input filter. The performance of the proposed converter is verified with the simulation and the experimental works.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1989년도 추계학술대회 논문집 학회본부
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• pp.325-326
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• 1989

His paper is concerned on the measurement of transformation fraction of steel using an eddy current sensor. Four stainless duplex samples with different transformation fraction are made and electromagnetic characteristics of the samples are measured.

• 전력전자학회논문지
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• 제20권6호
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• pp.491-497
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• 2015

This study proposes a new control method for a resistance spot welding inverter to improve weld quality. The proposed method is based on the dynamic resistance characteristics of steel sheets to be welded. A point in the second peak value of the dynamic resistance occurs during one shot of the welding current flow. A constant voltage control is applied from zero to the peak point, and a constant current control is adopted from the peak point to the end of the shot. The mixed mode control of the constant voltage and current guarantees high weld quality. Experiments are conducted with a 5 kA power supply and 0.5 mm steel sheets to compare quality. Experimental results show that weld quality is improved more than 10 times that of the conventional control method.

• 전력전자학회논문지
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• 제19권3호
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• pp.220-226
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• 2014

Input current ripple and harmonic components of the power device are main causes of electromagnetic interference (EMI). Although the discontinuous conduction mode (DCM) operation can reduce harmonic components of the power device by reducing reverse recovery current of diode and turn-off voltage spikes of the switch, input current ripple increases due to high peak to peak inductor current. Therefore, in this paper, frequency control algorithm is proposed to reduce the input current ripple of DCM operated interleaved boost converter. In the proposed algorithm, duty ratio is fixed either 0.33 or 0.67 to minimize the input current ripple and the switching frequency is controlled according to operating conditions. 600 W 3-phase interleaved boost converter prototype system is built to verify proposed algorithm.

• Journal of Power Electronics
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• 제13권1호
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• pp.122-138
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• 2013

Adaptive control of a peak current mode controlled (PCM) boost converter supplied by a PEM fuel cell is described in this paper. The adaptive controller with reference model and signal adaptation is developed in order to compensate the deviation of the response during the change of the operating point. The procedure for determining the adaptive algorithm's weighting coefficients, based on a combination of the pole-zero placement method and an optimization method is proposed. After applying the proposed procedure, the optimal adaptive algorithm's weighting coefficients can be determined in just a few iterations, without the use of a computer, thus greatly facilitating the application of the algorithm in real systems. Simulation and experimental results show that the dynamic behavior of a highly nonlinear control system with a fuel cell and a PCM boost converter, can fairly accurately be described by the dynamic behavior of the reference model, i.e., a linear system with constant parameters.

• 전력전자학회논문지
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• 제23권2호
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• pp.147-151
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• 2018

Phase-shift fullbridge (PSFB) converter detects the current in the primary side for operation of the peak current mode controller (PCMC). The PCMC must used the slope compensation to solve the problem when the effective duty is over 0.5. The voltage response of PSFB converters has slower than that of buck converter because of slew interval even if the voltage controllers of two converters have same bandwidth. To overcome these problems, this work proposes a compensating method of current reference considering slew interval and fast response in the PSFB converter. The effectiveness of the proposed method is proven using the PSIM simulation and experiment.

• Journal of Electrical Engineering and Technology
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• 제12권5호
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• pp.1970-1979
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• 2017

Ultra Lift Luo Converter (ULC) gained considerable research interest in recent years. The stability analysis of voltage mode and peak current mode controlled ULC in continuous conduction mode is analyzed in this paper. The Eigen value theory is used for the stability analysis of voltage mode controlled ULC. Then to characterize the dynamics of inner current loop, the expressions of closed loop transfer function and loop gain are determined. An algorithm has been developed to analyze the stability of the peak current mode controlled ULC. The theoretical results are correlated with the simulation results obtained using PSIM 9.1(SMARTCTRL 1.0) software. Finally it is proposed to fabricate a prototype and validate the performance by suitable experimental setup.

• JSTS:Journal of Semiconductor Technology and Science
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• 제13권1호
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• pp.58-64
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• 2013

In this paper, two new flip-flop circuits with PCRAM latches that are FF-1 and FF-2, respectively, are proposed not to waste leakage during sleep time. Unlike the FF-1 circuit that has a normal PCRAM latch, the FF-2 circuit has a selective write latch that can reduce the switching activity in writing operation to save switching power at sleep-in moment. Moreover, a sequential sleep-in control is proposed to reduce the rush current peak that is observed at the sleep-in moment. From the simulation of storing '000000' to the PCRAM latch, we could verify that the proposed FF-1 and FF-2 consume smaller power than the conventional 45-nm FF if the sleep time is longer than $465{\mu}s$ and $95{\mu}s$, respectively, at $125^{\circ}C$. For the rush current peak, the sequential sleep-in control could reduce the current peak as much as 77%.