• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 F
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• pp.1860-1862
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• 1998

This Paper presents a novel resonant switching Watkins-Johnson DC-DC converters. In the proposed converters, the basic steady-state analysis of the have been presented for the ZVS type Watkins-Johnson converter. From the results, it is shown that the output voltage of the converter is independant of load resistance, and is determined only by the switching frequency. Consequently, a design procedure is presented that minimizes voltage stress to the switch while maintaining ZVS for all loads.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2020년도 전력전자학술대회
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• pp.91-93
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• 2020

In recently days using distributed power generation systems constructed with boost type dc-dc converters is being extremely popularized because of the rising need of environment friendly energy generation power systems. In this paper a new constructed An efficient Step-Up DC-DC Converter for DC Grid Applications s proposed to boost a low level DC voltage(36-80V) to high DC bus (380V) level. When comparing to other step-up converters, the proposed topology has a reduced number of switching devices, can make high quality power with lower input current ripple and has wider input DC voltage range. Finally, the performance of the proposed topology is presented by simulation results with 350W hardware prototype.

• Journal of Power Electronics
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• 제10권3호
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• pp.270-276
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• 2010

In this paper, a capacitance estimation scheme for DC-link capacitors for single-phase AC/DC PWM converters is proposed. Under the no-load condition, a controlled AC current (30[Hz]) is injected into the input side, which then causes AC voltage ripples at the DC output side. Or, a controlled AC voltage can be directly injected into the DC output side. By extracting the AC voltage/current and power components on the DC output side using digital filters, the capacitance value can be calculated, where the recursive least squares (RLS) algorithm is used. The proposed methods can be simply implemented with software only and additional hardware is not required. From the experiment results, a high accuracy estimation of capacitances less than 0.85% has been obtained.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2001년도 전력전자학술대회 논문집
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• pp.223-226
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• 2001

In this paper, dc link ripple currents for three-phase ac/dc/ac PWM converters are analyzed in a frequency domain. The expression of the harmonic currents is developed by using switching functions and exponential Fourier series expansion. The dc link ripple currents with regard to power factor and modulation index are investigated. In addition, the effect of the displacement angle between the switching periods of line-side converters and load-side inverters on the do link ripple current is studied. The result of the do link current analysis is helpful in specifying the dc link capacitor size and its life time estimation.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2006년도 춘계학술대회
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• pp.551-554
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• 2006

An inverter system which consists of three bi-directional buck-boost converters, is proposed for motor driving. Three phase sinusoidal output voltages can be generated by utilizing three buck-boost converters. The advantage of this scheme is that it does not require a separate DC-DC converter for motor driving, i.e. inverter function is combined into the three DC-DC converters. This topology is suitable for inverters for hybrid or fuel cell vehicles where DC link voltage is subject to change depending upon charging status or output power. So the proposed system is capable of driving motor at high speed. The converter system is controlled by PI controller and simulation results done by MATLAB SIMULINK are provided.Ҙ?⨀ሉȀ̀㘰々K䍄乍?ጊ츀Ѐ㔹〻Ԁ䭃䑎䴀

• 전력전자학회:학술대회논문집
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• 전력전자학회 2020년도 전력전자학술대회
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• pp.455-456
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• 2020

This paper proposes stability evaluation of DC/DC boost converters based on output impedance in harmonic transfer function matrix considering line impedance and cascaded voltage and current control loops. The harmonic state-space (HSS) model of converter and controller is developed to obtain the harmonic transfer function matrix of closed-loop output impedance. This work is useful for impedance-based stability analysis of converters connected to DC power systems.

• Transactions on Electrical and Electronic Materials
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• 제17권2호
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• pp.57-68
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• 2016

In this study, we present the modern hybrid system based power generation for electric vehicle applications. We describe the hybrid structure of modified current source based DC - DC converters used to extract the maximum power from Photovoltaic (PV) and Fuel Cell system. Due to reduced dc-link capacitor requirement and higher reliability, the current source inverters (CSI) better compared to the voltage source based inverter. The novel control strategy includes Distributed Maximum Power Point Tracking (DMPPT) for photovoltaic (PV) and fuel cell power generation system. The proposed DC - DC converters have been analyzed in both buck and boost mode of operation under duty cycle 0.5>d, 0.5<d<1 and 0.5<d for capable electric vehicle applications. The proposed topology benefits include one common DC-AC inverter that interposes the generated power to supply the charge for the sharing of load in a system of hybrid supply with photovoltaic panels and fuel cell PEM. An improved control of Direct Torque and Flux Control (DTFC) based induction motor fed by current source converters for electric vehicle.In order to achieve better performance in terms of speed, power and miles per gallon for the expert, to accepting high regenerative braking current as well as persistent high dynamics driving performance is required. A simulation model for the hybrid power generation system based electric vehicle has been developed by using MATLAB/Simulink. The Direct Torque and Flux Control (DTFC) is planned using Xilinx ISE software tool in addition to a Modelsim 6.3 software tool that is used for simulation purposes. The FPGA based pulse generation is used to control the induction motor for electric vehicle applications. FPGA has been implemented, in order to verify the minimal error between the simulation results of MATLAB/Simulink and experimental results.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 춘계학술대회 논문집
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• pp.627-633
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• 2011

DC/DC switching power converters are commonly used to generate a regulated DC output voltages with high efficiencies from different DC input sources. The voltage mode DC/DC converter utilizes MOSFET, inductor, and a PWM (pulse-width modulation) controller with oscillator, amplifier, and comparator, etc. to efficiently transfer energy from the input to the output at periodic intervals. The fundamental boost converter and a buck converter containing a switched-mode power supply are studied. In this paper, the electrical characteristics of DC/DC power converters are simulated by program of SPICE. In addition, power efficiency is analyzed based on the specification of each component.

• 조명전기설비학회논문지
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• 제23권10호
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• pp.45-51
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• 2009

단상 벅-부스트 DC-AC 인버터는 2개의 DC-DC 컨버터로 이루어져 있다. 두 컨버터는 $180[^{\circ}]$의 위상차를 가지는 DC 바이어스된 정현파 기준 전압에 의해 구동된다. 교류로 출력되는 인버터의 최대값은 직류 입력전압 크기에 제약을 받지 않아 입력 직류전원보다 높은 교류 출력전압을 만들 수 있다. 본 논문에서는 벅-부스트 DC-AC인버터를 설계하고, 프로토타입을 제작하여 실험한다. 전압과 전류 제어기는 마이크로컨트롤러를 이용한 디지털 제어기로 구현된다.

• 조명전기설비학회논문지
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• 제22권6호
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• pp.34-43
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• 2008

상태 공간 평균화 모델은 강압형, 승압형 및 승 강압형 DC/DC 컨버터에 적용이 가능하며, 특별한 계산이 필요 없는 높은 정밀도가 증명된 모델이다. 이러한 모델은 전류연속모드(CCM) DC/DC 컨버터에서 확립되었으며, 본 논문에서는 컨버터의 전류연속모드(CCM) 모델로부터 의미 있는 결론을 유도하고자 한다. 본 논문에서는 스위치 평균모델을 이용한 DC/ DC 컨버터의 전류불연속모드(DCM) 모델링 및 임계특성에 관하여 논하였다. 스위치 평균 모델은 전류연속모드(CCM)와 전류불연속모드(DCM) 사이의 DC/DC 컨버터의 경계 조건에 대한 모델로부터 유추할 수 있으며, 시뮬레이션과 실험에 의해서 스위치의 평균 모델의 주파수 응답 특성을 예측할 수 있었다. 본 연구에서는 MOSFET를 사용하여 입력전압 15[V], 출력전압 24[V], 출력전력 24[W]급 시스템을 제작하여 실험하였다.