• Journal of Power Electronics
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• 제7권1호
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• pp.28-37
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• 2007

A new PWM-controlled quasi-resonant converter for a high efficiency PDP sustaining power module is proposed in this paper. The load regulation of the proposed converter can be achieved by controlling the ripple of the resonant voltage across the resonant capacitor with a bi-directional auxiliary circuit, while the main switches are operating at a fixed duty ratio and fixed switching frequency. Hence, the waveforms of the currents can be expected to be optimized from the view-point of conduction loss. Furthermore, the proposed converter has good ZVS capability, simple control circuits, no high voltage ringing problem of rectifier diodes, no DC offset of the magnetizing current and low voltage stresses of power switches. In this paper, operational principles, features of the proposed converter, and analysis and design considerations are presented. Experimental results demonstrate that the output voltage can be controlled well by the auxiliary circuit using the PWM method.

• 전력전자학회논문지
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• 제14권4호
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• pp.268-277
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• 2009

본 논문은 DTC-PWM을 적용한 PMSM의 속도제어 방식을 제안한다. 제안된 DTC-PWM은 기존의 DTC 방식과 PWM을 결합한 방식으로 스위칭 신호를 발생하는 구조를 가진다. 제안된 방식에서 실제 토크는 기존의 DTC 방식과 같이 추종되지만, 스위칭 신호는 토크 오차와 제어규칙에 따라 PWM 방식으로 제어한다. 토크와 자속을 제어하기 위한 스위칭 신호는 하나의 유효전압벡터와 영전압벡터로 구성되는 비대칭 스위칭 방식이 적용된다. 제안된 방식은 SVPWM과 같이 복잡한 계산없이 간단한 PWM의 연산으로 제어기를 구성하여 토크와 자속을 연속적으로 제어할 수 있다. 제안된 방식은 PMSM의 속도 제어 실험을 통하여 그 성능을 검증하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 D
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• pp.2577-2579
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• 2002

In this paper, we describe a CMOS DC-DC converter with a variable output voltage(8-12V @100mA) for a portable battery-operated system applications. The proposed DC-DC converter is used along with a Pulse-Frequency Modulation (PFM) method and consists of a reference circuit, a feedback resistor, a controller, and an internal oscillator. The integrated DC-DC converter with two external passive components(L.C) has been designed and fabricated on a 0.6${\mu}m$ 2-poly, 3-metal CMOS process and could be applied to the Personal Digital Assistants(PDA), Cellular Phone, Laptop Computer, etc.

• Journal of Power Electronics
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• 제16권3호
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• pp.840-848
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• 2016

A primary-side regulation AC-DC converter operating in the PFM (Pulse Frequency Modulation) mode with a high precision output current is designed, which applies a novel inductance compensation technique to improve the precision of the output current, which reduces the bad impact of the large tolerance of the transformer primary side inductance in the same batch. In this paper, the output current is regulated by the OSC charging current, which is controlled by a CC (constant current) controller. Meanwhile, for different primary inductors, the inductance compensation module adjusts the OSC charging current finely to improve the accuracy of the output current. The operation principle and design of the CC controller and the inductance compensation module are analyzed and illustrated herein. The control chip is implemented based on a TSMC 0.35μm 5V/40V BCD process, and a 12V/1.1A prototype has been built to verify the proposed control method. The deviation of the output current is within ±3% and the variation of the output current is less than 1% when the inductances of the primary windings vary by 10%.

• 전력전자학회논문지
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• 제15권6호
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• pp.432-440
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• 2010

본 논문에서는 단일 스위치를 사용한 LC 직렬 공진형 부스트 컨버터를 제안하였다. 제안하는 토폴로지는 별도의 보조 스위치의 추가 없이 일반 부스트 컨버터에 수동소자만을 추가하여 스위치 턴-온, 턴-오프 시 영전압 스위칭(ZVS; Zero Voltage Switching)을 수행한다. 이 토폴로지는 LC직렬 공진에 의해 스위치 오프 타임이 결정되므로, 스위치 온 타임을 가변하여 출력전압을 조절하는 온 타임 가변형 주파수 변조 기법으로 제어된다. 전류 도통 경로에 따라 제안된 회로의 동작 모드를 구분하였고, 제안된 컨버터의 동작모드와 특성은 수학적 해석과 시뮬레이션 및 실험을 통해서 검증하였다.

• 한국통신학회논문지
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• 제27권1A호
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• pp.1-12
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• 2002

초광대역 통신은 전 주파수 대역에 걸쳐 스펙트럼이 마치 기저 대역 잡음과 유사한 형태로 존재하여 타 통신시스템에 간섭을 주지 않고 고속의 통신이 가능하며, 반송파를 사용하지 않기 때문에 송${\cdot}$수신기의 소비 전력과 그 구조를 간략화 시킬 수 있다. 본 논문에서는 평균값이 0이고 대칭성을 갖는 레일리 모노펄스 Antipodal 방식을 처음으로 적용하여 초광대역 신호를 구성하고 시간 도약 부호를 적용하여 다중접속 시스템을 제안하였다. AWGA에서 레일리 모노펄스에 대한 오류확률, 다중접속시 사용자의 수, 전송속도에 대해 수치해석을 통해 시스템의 성능을 비교, 분석하였다. 그 결과 제안한 Antipodal 방식은 기존의 펄스 위치 변조 방식보다 오류확률, 사용자의 수 및 전송속도 면에서도 유리함을 보였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 C
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• pp.908-910
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• 1998

Modern AC electric car has PWM(Pulse Width Modulation) -controlled converters, which give rise to higher harmonics. The current harmonics injected from AC electric car is propagated through power feeding circuit. As the feeding circuit is a distributed constant circuit composed of RLC, the capacitance of the feeding circuit and the inductance on the side of power system cause a parallel resonance and a magnification of current harmonics at a specific frequency. The magnified current harmonics usually brings about various problems. That is, the current harmonics makes interference in the adjacent lines of communications and the railway signalling system. Furthermore, in case it flows on the side of power system, not only overheating and vibration at the power capacitors but also wrong operation at the protective devices can occur. Therefore, the exact assessment of the harmonic current flow must be undertaken at design and planning stage for the electric traction systems. From these point of view, this study presents an approach to model and to analyse traction power feeding system focused on the amplification of harmonic current. The proposed algorithm is applied to a standard AT(Auto-transformer)-fed test system in which electric car with PWM-controlled converters is running.

• 한국전기전자재료학회논문지
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• 제22권5호
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• pp.431-435
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• 2009

The apparatus has been fabricated using the laser diode and microprocessor unit. The apparatus used a InGaAlP laser diode for laser medical therapy and was designed for a pulse width modulation type to increase stimulation effects. To raise the stimulus effect of the human body, the optical irradiation frequency could be set up. The study has executed in-vivo experiment by employing our own developed laser diode irradiation system to investigate the effects of the InGaAlP laser diode irradiation on the wound healing as a preliminary study aimed at the application of InGaAlP laser diode to wound healing of human skin injury. The study cut out whole skin layers of Sprague-Dawley rat on the back part in 1 cm circle and observed developing effects after executing light irradiation for 9 days, and in result it is found that the light irradiation rat showed earlier wound healing than non-irradiation rat during the experimental period. In addition, there are some differences found regarding the healing process between laser diode irradiated rats and non-irradiated ones.

• 전력전자학회논문지
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• 제25권1호
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• pp.44-53
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• 2020

A bridgeless single-stage AC-DC converter for wireless power charging systems is proposed. This converter is composed of a PFC stage and a three-level hybrid DC-DC stage. The proposed converter can control the wide output voltage (200-450 V_DC) by the variable link voltage and the pulse-width voltage applied to the primary resonant circuit due to the phase-shifted modulation at a fixed switching frequency. Moreover, the input power factor and the total harmonic distortion can be improved by using the proposed converter. A 1 kW prototype was fabricated and validated through experimental results and analysis.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1993년도 하계학술대회 논문집 A
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• pp.227-230
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• 1993

Recently, the development of novel control methodology enables us to improve the performance of AC-machine drives by using pulse width modulation (PWM) technique. Usually, the dynamic characteristic of induction motor (IM) has been represented by the 5-th order nonlinear differential equation. This dynamics, however, can be reduced to 3-rd order dynamics by applying direct control of IM input current. This methodology concludes that it is much easier to control IM by means of the field-oriented methods employing the current controller. Therefore a precise current control is crucial to achieve a high control performance both in dynamic and steady state operations. This paper presents an adaptive fuzzy current controller with artificial neural network (ANN) for field-oriented controlled IM. This new control structure is able to adaptively minimize a current ripple while maintaining constant switching frequency. Especially the proposed controller employs neuro-computing philosophy as well as adaptive learning pattern recognizing principles with respect to variations of the system parameters. The proposed approach is applied to the IM drive system, and its performance is tested through various simulations. Simulation results show that the proposed system, compared among several known classical methods, has a superb performance.