• Proceedings of the KIPE Conference
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• 2018.07a
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• pp.12-14
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• 2018

본 논문에서는, 넓은 입력전압 범위에서 높은 효율을 가지는 비대칭 하프-브릿지 컨버터를 제안한다. 비대칭 하프-브릿지 컨버터는 적은 소자수를 가지고, 영전압 스위칭이 가능한 특징으로 인해 작은 용량의 전원장치에서 널리 쓰이는 토폴로지이다. 하지만, 비대칭 하프-브릿지 컨버터는 넓은 입력전압 범위에서 설계되면 변압기에 큰 DC-오프셋 전류를 가지기 때문에, 변압기의 크기를 증가시키고 영전압 스위칭 에너지를 감소시키는 문제점을 갖는다. 따라서 이를 해결하기 위해, 제안하는 회로는 결합 인덕터를 사용한 새로운 구조의 정류기를 사용하여 변압기의 오프셋 전류를 제거한다. 이로 인해 제안하는 회로는 오프셋 전류로 인해 발생하는 문제점을 해결하여 넓은 입력전압 범위에서도 높은 효율을 가진다. 제안하는 회로의 효용성을 증명하기 위해 250-400V 입력전압과 100V/200W의 출력에서 실험이 진행되었다.

• Journal of Power Electronics
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• v.3 no.4
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• pp.224-229
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• 2003

The rapid expansion of small computers over the last 10-odd years has brought about great changes in the circumstances affecting UPSs. There are strong demands that UPSs become much smaller and lighter, and more economical, which has resulted in the wide application of the circuit topology without transformer. A disadvantage of such UPS topology is that the DC link voltage is very high, which invites decreased reliability and increased cost of battery bank. Some circuit configurations were proposed to eliminate this disadvantage, but they still had problems. In this paper, a novel circuit configuration which eliminates these problems is proposed and evaluated by the experimental results of prototype UPS.

• Journal of Magnetics
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• v.13 no.2
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• pp.37-42
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• 2008

In this paper, design parameters of high Q (> 50), high current inductor for on-chip power module were optimized by 4 Xs 3 Ys DOE (Design of Experiment). Coil spacing, coil thickness, ferrite thickness, and permeability were assigned to Xs, and inductance (L) and Q factor at 10 MHz, and resonance frequency ($f_r$) were determined Ys. Effects of each X on the Ys were demonstrated and explained using known inductor theory. Multiple response optimizations were accomplished by three derived regression equations on the Ys. As a result, L of 125 nH, Q factor of 197.5, and $f_r$ of 316.3 MHz were obtained with coil space of $127\;{\mu}m$, Cu thickness of $67.8\;{\mu}m$, ferrite thickness of $130.3\;{\mu}m$, and permeability 156.5. Loss tan ${\delta}=0$ was assumed for the estimation. Accordingly, Q factor of about 60 is expected at tan ${\delta}=0.02$.

• Journal of IKEEE
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• v.19 no.4
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• pp.506-513
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• 2015

In this paper, an output-capacitorless, low-dropout (LDO) regulator is designed, which consumes $4.5{\mu}A$ quiescent current. Proposed LDO regulator is realized using two amplifier for good load regulation and fast response time, which provide high gain, high bandwidth, and high slew rate. In addition, a one-shot current boosting circuit is added for current control to charge and discharge the parasitic capacitance at the pass transistor gate. As a result, response time is improved during load-current transition. The designed circuit is implemented through a $0.11-{\mu}m$ CMOS process. We experimentally verify output voltage fluctuation of 260mV and recovery time of $0.8{\mu}s$ at maximum load current 200mA.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.11
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• pp.1408-1414
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• 2018

Recently, as a solution to the problem of maintaining system reliability, stability, and quality occurring worldwide, such as activation of smart grid and recognition of super grid and rapid grid interconnection of renewable energy sources HVDC(High Voltage Direct Current) will appear on the front of the electric power system. These concepts are also very important concepts in HVDC systems. When the HVDC system is linked to the existing power system, it is composed of AC/DC/AC conversion device, and these conversion devices are composed of many thyristors. These parts(Devices) are connected in a complicated manner, and they belong to the one with a higher failure rate. However, the problem of establishing the concept of failure rate of HVDC parts directly linked to economic efficiency and the understanding accompanying it are still insufficient. Therefore, in this paper, we establish the meaning of reliability in power system and try to develop a model to analyze and verify the failure rate data of HVDC based on this.

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.648-653
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• 1998

The conventional three-phase rectifier with bulky LC output filter has been widely used in the industry because of its distinctive advantages over the active power factor correction rectifier such as simple circuit, high reliability, and low cost. Over than 0.9 power factor can be achieved, which is acceptable in most of industry applications. This rectifier, however, is not easy to use for high power density applications since the LC filter is bulky and heavy. To solve this problem, a new simple rectifier is presented in this paper. By eliminating the bulky LC filter from the conventional diode rectifier without losing most of the advantages of the conventional rectifier, very high power density power conversion with high power factor can be achieved. Operation principle and design considerations are illustrated and verified by Pspice simulation and experimental results from a prototype of 3.3 kW rectifier followed by 100KHz zero voltage switching full bridge PWM converter

• ETRI Journal
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• v.41 no.2
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• pp.254-261
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• 2019

Distinct from conventional energy-harvesting (EH) technologies, such as the use of photovoltaic, piezoelectric, and thermoelectric effects, betavoltaic energy conversion can consistently generate uniform electric power, independent of environmental variations, and provide a constant output of high DC voltage, even under conditions of ultra-low-power EH. It can also dramatically reduce the energy loss incurred in the processes of voltage boosting and regulation. This study realized betavoltaic cells comprised of p-i-n junctions based on silicon carbide, fabricated through a customized semiconductor recipe, and a Ni foil plated with a Ni-63 radioisotope. The betavoltaic energy converter (BEC) includes an array of 16 parallel-connected betavoltaic cells. Experimental results demonstrate that the series and parallel connections of two BECs result in an open-circuit voltage $V_{oc}$ of 3.06 V with a short-circuit current $I_{sc}$ of 48.5 nA, and a $V_{oc}$ of 1.50 V with an $I_{sc}$ of 92.6 nA, respectively. The capacitor charging efficiency in terms of the current generated from the two series-connected BECs was measured to be approximately 90.7%.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.21 no.1
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• pp.148-156
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• 2007

This paper explains stocker system that is operated in the long distance and linear area. The power system of stocker system uses Contactless Power Supply(CPS) to reduce problems of particle generation. The circuit configuration of CPS is simplified than the conventional ones, and the prototype is designed for commercial product. To transfer output data(information) from crane(secondary vehicle system) of the CPS to Primary system optical modem and TMS320F243(DSP, TI) are used between primary and secondary. power system are used, and the output voltage is controlled by operating frequency modulation. This paper is applied to stocker system controlled as one to one communication between the moving part(secondary system) and fixed part(primary system) of crane using optical modem. The study makes one to multi communication between fixed part and moving part for the purpose of multi crane operation of stocker system and must be done in the future.

• Journal of Power Electronics
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• v.14 no.3
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• pp.444-457
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• 2014

This paper presents the design and realization of a digital PV simulator with a Push-Pull Forward (PPF) circuit based on the principle of modular hardware and configurable software. A PPF circuit is chosen as the main circuit to restrain the magnetic biasing of the core for a DC-DC converter and to reduce the spike of the turn-off voltage across every switch. Control and I/O interface based on a personal computer (PC) and multifunction data acquisition card, can conveniently achieve the data acquisition and configuration of the control algorithm and interface due to the abundant software resources of computers. In addition, the control program developed in Matlab/Simulink can conveniently construct and adjust both the models and parameters. It can also run in real-time under the external mode of Simulink by loading the modules of the Real-Time Windows Target. The mathematic models of the Push-Pull Forward circuit and the digital PV simulator are established in this paper by the state-space averaging method. The pole-zero cancellation technique is employed and then its controller parameters are systematically designed based on the performance analysis of the root loci of the closed current loop with $k_i$ and $R_L$ as variables. A fuzzy PI controller based on the Takagi-Sugeno fuzzy model is applied to regulate the controller parameters self-adaptively according to the change of $R_L$ and the operating point of the PV simulator to match the controller parameters with $R_L$. The stationary and dynamic performances of the PV simulator are tested by experiments, and the experimental results show that the PV simulator has the merits of a wide effective working range, high steady-state accuracy and good dynamic performances.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.6
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• pp.2722-2728
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• 2011

3Phase PWM rectifier has become increasingly popular due to its capability of nearly sinusoidal waveform of the input current, and nearly unity power factor operation as a AC/DC rectifier of high capacity telecommunication power supply system. Generally, PI controller is used as a voltage controller of PWM rectifier and voltage controller must be designed to have low overshoot in transient state to get a reliability and stable operation. However, in the application of telecommunication in which load condition is varied very fast, the voltage controller must have a large bandwidth to reduce output voltage variation. The PI controller with large bandwidth arouse the excessive overshoot of the output voltage, and this large output voltage variation degrades the reliability of communication power of the three-phase PWM Rectifier. In this paper, new IP voltage controller for 3 phase PWM rectifier is proposed which has relatively low transient output voltage variation. The improved output characteristics of the transient state voltage responses of the starting and at load changes of the proposed voltage controller are proved by simulations and experiments.