• The Transactions of the Korean Institute of Electrical Engineers B
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• v.51 no.4
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• pp.165-173
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• 2002

The goal of this paper is optimal switching angle of switched reluctance motor drive system fur maximum energy ratio. A new magnetizing method with a low-frequency increasing the energy conversion ratio that is related to the efficiency of motor is proposed. As the results, it improved the efficiency about 2[%]. And a torque ripple is also sufficiently reduced compared with that of the conventional approach. In order tn start softly regardless of large ripple torque, the profile of phase current is predicted by the ANFIS, and current control mode was adapted when it is operated under the starting speed. Variable implementations en the fields will guarantee the more practical drive system.

• Journal of IKEEE
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• v.15 no.4
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• pp.319-323
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• 2011

In this paper presents a new model of dual-mode synchronous buck converter with dynamic control for mobile applications was proposed. The proposed circuit can operate at 2.5MHz with supply voltage 2.5V to 5V for low ripple and minimum inductor and capacitor size, which is suitable for single-cell lithium-ion battery supply mobile applications. For high efficiency, the proposed circuit adopts synchronous type and dynamic control. The proposed circuit is designed by using the device parameter of TSMC 0.18um BCD process and the performance is evaluated by Cadence spectre. Experimental board level results show the maximum conversion efficiency is 96% at 100mA load current.

• Journal of the Korean Society for Railway
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• v.10 no.1 s.38
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• pp.51-56
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• 2007

In this paper, control schemes are developed for a propulsion system(Converter/Inverter) in electrical train. A robust controller for PWM converter is proposed. The converter controller consists of a PI controller for DC output voltage and a current controller using error-space approach for maintaining the sinusoidal current waveform and unity power factor. This proposed method is based on characteristic ratio assignment(CRA) method which has the advantage to design the optimal gain to meet the referenced response and overshoot within the limit range. Inverter system is controlled by vector control and slip frequency control. At low speed region, vector control scheme is applied to control instantaneous torque and slip frequency control is performed under overmodulation region and one pulse mode. Because output voltage of converter contains harmonics ripple at twice input ac line frequency, control scheme is developed to reduce the pulsating torque current. The performance of propulsion system will be verified by simulation and prototype experimental results.

• Proceedings of the KIPE Conference
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• 2013.07a
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• pp.397-398
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• 2013

Fairchild Green Mode off line buck switch for low standby power consumption and high reliability is presented. By reducing operating current and optimizing switching frequency, 20mW power consumption is achieved. High performance trans-conductance amplifier and green mode function improve the ripple and regulation in the output voltage. The conventional $FPS^{TM}$ buck and novel Fairchild buck switch are compared to show the improvement of performance. Experimental results are showed using 2W evaluation board.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.21 no.4
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• pp.61-72
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• 2007

This study proposed a high efficiency DC-DC converter with a new current doubler rectifier for fuel-cell systems for use with the Nexa(310-0027) PEMFC from the Ballard Co. The proposed high efficiency DC-DC converter for the fuel-cell system generated ZVS by applying partial resonance and using a phase shift PWM control method. Constantly switching frequency, loss of switching, peak current, and peak voltage were reduced by this system. In addition to this system, two inductors were attached to a rectifier circuit allowing it to be able to provide the direct current(DC) and DC voltage safely to a load with reduced ripple components. Also, by using the newly proposed current doubler rectifier, the high frequency DC-DC converter for the fuel cell system was capable of reaching a highest efficiency of 92[%] as compared to 88.3[%] efficiency in previous results, which means that efficiency increased 3.7[%]. The overall results were confirmed by a simulation and laboratory experiment.

• Journal of Power Electronics
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• v.16 no.3
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• pp.994-1003
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• 2016

Two major obstacles in the utilization of electrical vehicles are their price and range. The collaboration of direct torque control (DTC) with induction motor (IM) is preferred for its low cost, easy implementation, and parameter independency. However, in terms of edges, the method has drawbacks, such as variable switching frequency and undesired current harmonic distortion. These drawbacks result in acoustic noise, reduced efficiency, and electromagnetic interference. A feed-forward approach for stator-flux-oriented DTC with space vector pulse-width modulation is presented in in this paper. The outcome of the proposed method is low current harmonic distortion with fixed switching frequency while preserving the torque performance and simple application feature of basic DTC. The method is applicable to existing and forthcoming IM drive systems via software adaptation. The validity of the proposed method is confirmed by simulation and experimental results.

• Proceedings of the KIPE Conference
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• 2018.07a
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• pp.192-194
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• 2018

In this paper a new single-stage ac-dc converter with high frequency isolation and low components count is introduced. The proposed converter is constructed using two interleaved boost circuits in the grid side and non-regulating full bridge in the DC side. An optimized switching is implemented on the two interleaved boost circuits resulting in a ripple-free grid current without a ripple cancellation network; hence very small filter inductors are used. A simple and reliable closed-loop control system is easily implemented, since the phase-shift angle is the only independent variable. Moreover, current imbalance is avoided in the presented topology without current control loop in each phase. The proposed charger charges the battery with a sinusoidal-like current instead of a constant direct current. ZVS turn on of all switches is achieved throughout the operation in both directions of power flow without any additional components.

• Journal of Power Electronics
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• v.12 no.3
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• pp.429-438
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• 2012

This paper presents the use of a novel, single-stage high-power-factor electronic ballast with a symmetrical class-DE low-$d{\upsilon}$/$dt$ resonant rectifier as a power-factor corrector for fluorescent lamps. The power-factor correction is achieved by using a bridge rectifier to utilize the function of a symmetrical class-DE resonant rectifier. By employing this topology, the peak and ripple values of the input current are reduced, allowing for a reduced filter inductor volume of the EMI filter. Since the conduction angle of the bridge rectifier diode current was increased, a low-line current harmonic and a power factor near unity can be obtained. A prototype ballast, operating at an 84-kHz fixed frequency and a 220-$V_{rms}$, 50-Hz line input voltage, was utilized to drive a T8-36W fluorescent lamp. Experimental results are presented which verify the theoretical analysis.

• Journal of IKEEE
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• v.18 no.3
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• pp.320-327
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• 2014

Recently, Importance of power management circuit technology is increased with the development of portable electric devices. This paper presents a high performance DC-DC buck converter for mobile applications. Especially, presented design have low ripple voltages and driving capability of large load current. A designed voltage mode 2-phase DC-DC converter is implemented in a $0.35{\mu}m$ CMOS process, and the overall size is $2.35{\times}2.35mm^2$. The peak efficiency is 91% with a 4MHz frequency and the maximum load current is 4A.

• Proceedings of the KIEE Conference
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• 1994.11a
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• pp.138-140
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• 1994

In this paper, a three-phase active power filter using voltage- source PWM converter is designed to eliminate the harmonics and compensate the reactive power in the ac side. The predictive current control method is adopted, which provides constant switching frequency and low current ripple but has inherently one sampling error between the command and the actual current. Here we propose the algorithm which corrects this delay time. The converter voltage obtained from this current control can be accomplished by the space vector modulation method at a voltage-type converter. All control sequences of active filter is executed by a DSP which is designed to calculate floating points at very hight speed. Finally, the validity of this filter using the predictive current control method is demonstrated through experimental results.