• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제55권12호
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• pp.608-616
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• 2006

Recently, a switched reluctance motor is widely used in various industries because it has many advantages such as a simple structure, robustness, less maintenance, high torque/weight ratio, and easy speed control over other types of motors. However, a switched reluctance motor inherently produces acoustic noise and vibration caused by torque ripple. Applications of these motors where silent operation is desirable have thus been limited. In this paper, a new stator pole face having a non-uniform air-gap and a pole shoe attached to the lateral face of the rotor pole are suggested in order to minimize torque ripple. The effects of each design parameter are validated using a time-stepping finite element method. The parameters are optimized by utilizing response surface method (RSM) combined with (1+1) evolution strategy. The result shows that the optimized shape gives higher average torque and drastically reduced torque ripple.

• 조명전기설비학회논문지
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• 제18권6호
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• pp.230-237
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• 2004

본 논문에서는 인버터에서 발생하는 맥동전류가 양자 교환막형 연료전지에 미치는 영향을 임피던스 모델을 통하여 분석한다. 제안된 방법은 주파수 응답 분석법을 이용하여 연료전지 스택의 등가 임피던스를 유도하고, 유도된 모델을 이용하여 맥동전류의 영향을 분석한다. 모델을 통해 계산된 결과는 상용 연료전지 스택을 사용한 실험을 통하여 증명된다. 실험결과는 인버터에 의해 발생한 맥동전류로 인해 최대 10(%)까지 연료전지 스택의 출력이 감소할 수 있음을 보인다.

• 전기학회논문지
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• 제67권4호
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• pp.531-537
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• 2018

This paper propose a bidirectional dc-to-dc converter employing dual inductor for current ripple reduction. Conventional bidirectional dc-to-dc converter uses a single inductor for two different modes; boost and buck; therefore it is difficult to satisfy the optimized inductance value for each mode. To improve this problem, the proposed converter adds two switches, a diode, and one inductor. By proper switching of the additional switch, the proposed converter operates with a inductor in boost mode, but it works with dual inductor in buck mode. Hence in both modes the proposed bidirectional converter can be operated with optimized inductance values. Most of all the optimized inductance in buck mode can reduce the current ripple and its effective value(rms), which are directly related to the temperature increase resulted in short lifetime of battery. To verify the validity of the proposed approach, we first analyzes the operation of the proposed converter theoretically, and implement computer-aided simulations and experiments using a prototype.

• 조명전기설비학회논문지
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• 제27권2호
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• pp.102-109
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• 2013

In this paper, a new torque predictive control method of interior permanent magnet synchronous motor is developed based on an extended rotor flux. Also, a duty ratio prediction method is proposed and allows the duty ratio of the active stator voltage vector to be continuously calculated. The proposed method makes it possible to relatively reduce the torque ripple under the steady state as well as to remain the good dynamic response in the transient state. With the duty ratio prediction method, the magnitude and time interval of the active stator voltage vector applied can be continuously controlled against the varying operation conditions. This paper shows a comparative study among the switching table direct torque control(DTC), the SVM-DTC, conventional torque predictive control, and the proposed torque predictive control. Simulation results show validity and effectiveness of this work.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2016년도 전력전자학술대회 논문집
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• pp.365-366
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• 2016

This paper presents a single-phase transformerless photovoltaic (PV) power converter systems based on the AC/DC boost inverter, which is capable of solving the leakage current and second-order ripple power issues. By eliminating the inherent ripple power in single-phase inverter, the bulky electrolytic capacitor can be replaced by a small film capacitor. The validity of the proposed scheme has been verified by the simulation results.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 B
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• pp.900-902
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• 2002

This paper deals with reduction of torque ripple of slotless PM linear synchronous motor (PMLSM) with divided permanent magnet using 2D analytical method. To confirm the validity of this study, analysis values by analytical method are comprared with the results of 2D FEM and experimental results. And the results of divided PM model is compared with none divided PM model.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2004년도 학술대회 논문집
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• pp.237-240
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• 2004

For the paralleled operation of DC/DC converters, the current sharing between each modules is the most important for the reliability of the power system. Interleaving method is commonly used with many paralleling schemes for the reduction of the ripple in the output voltage of paralleled converters and there are many commercial IC for interleaving application appliable. But for all of them, it is impossible to detect the number of module in operating and then change the phase of them automatically. In this paper, a novel paralleling method is proposed for the converter parallel operation, which detects the number of modules in active and sets the phases of PWM signals applied to each modules autonomously. This can greatly improve the output voltage ripple and reliability of the system. The expandibility of modular number can be done very easily by just adding several parts.

• Journal of Electrical Engineering and Technology
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• 제8권5호
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• pp.1062-1069
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• 2013

This paper proposes a simple current compensation method to improve the control performance of B4 inverters. Four-switch inverters so called B4 inverters employ only four switches. They have a split dc-link and one phase of three-phase motors is connected to the center-tap of split dc-link capacitors in B4 inverters. The voltage ripples in the center tap of the dc-link generate unbalanced three-phase voltages causing current ripples. To solve this problem, this paper presents a simple compensation method that adjusts switching times considering dc-link voltage ripples. The validity of the proposed method is verified by simulations and experiments carried out with a 1 HP induction machine.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 추계학술대회논문집
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• pp.816-821
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• 2002

It is getting more important that energy efficiency and manufacturing cost of the electric motor in appliance. The SRM has been alternative choice. But acoustic noise and harshness in this motor was widely known. So this paper had been studied on the noise reduction of a SRM in air conditioner. This works include some parameters regarding to blown noise sources like a reluctance torque ripple, air gap eccentricity, Especially, it was focused on dynamic characteristics of the system based on mechanical viewpoint. It came to successful results. Besides, this gave us a validity of phase excitation in experimental measurements.

• 한국측량학회지
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• 제14권1호
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• pp.111-118
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• 1996

본 연구는 수치지형모델로부터 지형을 대표할 수 있는 임계점을 추적하는데 목적을 두었다. 지형의 임계점은 주위 인접점으로부터 급격한 변화가 이루어지는 점으로 생각할 수 있다. 본 연구에서는 라플라스 연산자를 중심으로 이들의 최적 추적방법이 연구되어지며 조그만 리플을 제거하기 위한 노이즈 제거 시스템이 적용되어진다. 연구결과 라플라스 연산자는 지형의 임계점을 효과적으로 추출함을 알 수 있었으며 국소적인 분산간에 의한 노이즈 제거 시스템은 조그만 리플을 제거하는데는 효과적이었으나, 지형의 형상을 재현시키는데는 비효과적임을 알 수 있었다.