• Proceedings of the KIPE Conference
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• 2007.07a
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• pp.182-184
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• 2007

본 논문에서는 2단 AC/DC 컨버터와 단일단 AC/DC 컨버터가 가지고 있는 단점들을 개선 할 수 있는 새로운 준 단일 전력단 컨버터를 제안한다. DC/DC 단으로는 동적 특성이 좋은 LLC 컨버터를 채용하여 별도의 제어기 없이 고정 주파수 및 고정 Duty(50%) 발생기에 의해 Open Loop로 구동 시킴으로써 저가격화 및 고효율화를 획득 할 수 있다. 또한 역률개선단은 Boost 컨버터를 채용하고 간단한 제어기 1개를 사용하여 역률 개선과 동시에 DC/DC 단의 최종출력을 제어한다. 기존 2단 PFC 컨버터와는 다르게 PFC 링크전압을 Feedback 하지 않고 DC/DC 단의 최종 출력을 Feedback 하여 제어한다. 제안된 회로의 우수성 검증을 위해 600W급 시작품을 이용한 실험 결과를 제시한다.

• Proceedings of the KIPE Conference
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• 2017.07a
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• pp.138-139
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• 2017

This paper describes the design and implementation of a trigger circuit which can be series connected with main pulse circuit for a xenon flash lamp driver. For generating high voltage, the trigger circuit is designed as an inductive energy storage pulsed power modulator with 2 state step-up circuit consisting of a boost converter and a flyback circuit. In order to guarantee pulse width, a resonant capacitor on the output side of the flyback circuit is designed. This capacitor limits the output voltage to protect the flyback switch. In addition, to protect another power supply of xenon flash lamp driver from trigger pulse, the high voltage transformer which can carry the full current of main pulse is designed. To verify the proposed design, the trigger circuit is developed with the specification of maximum 23 kV, 0.6 J/pulse output and tested with a xenon flash lamp driver consisting of a main pulse circuit and a simmer circuit.

• Journal of Electrical Engineering and Technology
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• v.9 no.2
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• pp.589-599
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• 2014

On the basis of the traditional ZSI (Z-source inverter), this paper presents a ESL-${\Gamma}$-ZSI, which uses a unique ${\Gamma}$-shaped impedance network and an extended SL network for boosting its output voltage in addition to their usual voltage-buck behavior. The inverter can increase the boost factor through adjusting shoot-through duty ratio and increasing the number of inductors. Capacitor voltage stress of ESL-${\Gamma}$-ZSI is a constant when 1>D>0, and ESL-${\Gamma}$-ZSI has small inductor current stress. The working principle of ESL-${\Gamma}$-ZSI and comparison with the classical ZSI and SL- ZSI are analyzed in detail. The power loss comparison between ESL-${\Gamma}$-ZSI and Cuk converter is analyzed detailedly. Simulation and experimental results are given to demonstrate the operation features of the inverter.

• Journal of Electrical Engineering and Technology
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• v.8 no.4
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• pp.752-759
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• 2013

This paper proposes a method for fault diagnosis and fault-tolerant control of DC-link voltage sensor for two-stage three-phase grid-connected PV inverters. Generally, the front-end DC-DC boost converter tracks the maximum power point (MPP) of PV array and the rear-end DC-AC inverter is used to generate a sinusoidal output current and keep the DC-link voltage constant. In this system, a sensor is essential for power conversion. A sensor fault is detected when there is an error between the sensed and estimated values, which are obtained from a DC-link voltage sensorless algorithm. Fault-tolerant control is achieved by using the estimated values. A deadbeat current controller is used to meet the dynamic characteristic of the proposed algorithm. The proposed algorithm is validated by simulation and experiment results.

• The Transactions of the Korean Institute of Power Electronics
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• v.12 no.4
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• pp.285-290
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• 2007

When input parameters like gas volume or load of the fuel cell system is changed, the fuel cell system can generate transient voltage disturbances. In this paper, a fuel cell system with Z-source inverter and ultracapacitors for voltage disturbance compensation is proposed. The structure of Z-source inverter is simple. It has unique features that can boost/buck input voltage with a DC/DC converter using only a modified switching pattern. The characteristics of the proposed topologies for the fuel cell system with Z-source inverter and ultracapacitors are analyzed using simulation, and verified by experiments. The simulation and experimental results show that the proposed system is capable of operating with stable response to the system transient and voltage disturbances.

• Proceedings of the KIEE Conference
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• 2003.11c
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• pp.349-352
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• 2003

A personal low-frequency stimulator is a portable device to relax muscle pains of a person. The stimulator generates combined low-frequency pulses to be applied to pads attached to painful muscles. This paper reports a development of such device with its characteristic analyses. The major components of our stimulator are MCU, high-voltage generating circuit part, high-voltage switching circuit part, input switch part and display unit. High-voltage generating circuit is designed by using a boost converter circuit and allows user control of the output voltage. High-voltage switching circuit, controlled by MCU, generates output voltage to be applied to pads. Input switch part is composed of power supply, intensity selection, mode selection and memory. Display unit adopts a text LCD module to display modes, Intensity, output frequency and user set-up time. Our designed safety circuit, to protect human body from possible electric shock, slowly increases the output voltage to the selected output intensity. It continuously checks the output pulse shape and disable the output when dangerous pulses are detected. This paper also shows some experimental results.

• New & Renewable Energy
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• v.8 no.3
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• pp.14-22
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• 2012

Performance of photovoltaic (PV) generator systems relies on its operating conditions. Maximum power extracted from PV generators depends strongly on solar irradiation, load impedance, and ambient temperature. A most maximum power point tracking (MPPT) algorithm is based on a perturb and observe method and an incremental conductance method. It is well known the latter is better in terms of dynamics and tracking characteristics under condition of rapidly changing solar irradiation. However, in case of digital implementation, the latter has some error for determining a maximum power point. This paper presents a PID based MPPT algorithm for such PV systems. We use neural network technique for determining PID parameters by online learning approach. And we construct a boost converter to regulate the output voltage from PV generator system. Computer simulation is carried out to evaluate the proposed MPPT method and we accomplish comparative study with a perturb and observe based MPPT method to prove its superiority.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.3
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• pp.540-548
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• 2007

The parer proposes a power factor correction high efficiency PWM single-phase rectifier. Its good characteristics such as simple PWM control, low switch stress, and low VAR rating of commutation circuits make the proposed rectifier very suitable for various unidirectional power applications. In addition, the proposed rectifier consists of three boost-converter-type IGBT modules with the switching devices located at the bottom leg of the rectifier scheme, which also enables the use of the same power supply in both control and gate driver, thus resulting in simple control and power circuit structure. The detailed principle of operation and experimental results are also included. In particular, the design guide line is also suggested to make the circuit design of the proposed rectifier easy and fast.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.21 no.6
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• pp.117-125
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• 2007

Recently, a fuel cell with low voltage and high current output characteristics is remarkable for new generation system. It needs both a DC-DC step-up converter and DC-AC inverter to be used in fuel cell generation system. Therefor, this paper, consists of an isolated DC-DC converter to boost the fuel cell voltage 380[VDC] and a PWM inverter with LC filter to convent the DC voltage to single-phase 220[VAC]. Expressly, The fuel cell system which it proposes DC-DC the efficient converter used PWM the phase transient control law and it depended to portion resonance ZVS switching, loss peek voltage and electric current of realization under make schedule, switching frequency anger and the switch reduction. And mind benevolence it sprouted 2 in stop circuit and it added and a direct current voltage and the electric current where the ingredient is reduced in load side ripple stable under make whom it will be able to supply. Besides the efficiency of 92[%]is obtained over the wide output voltage regulation ranges and load variations. Also, under make over together the result leads simulation and test, the propriety confirmation.

• Journal of Energy Engineering
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• v.15 no.3 s.47
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• pp.181-187
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• 2006

This paper is proposed to a solar cell power system used in fire emergency equipment. Also it is designed with a high efficiency power converter in order to increase efficiency of power system. The controlling switches used in DC-DC booster chopper and DC-AC inverter are operated with soft switching, which is applied to resonant circuit method to reduce switching loss. The result is that the system gets to high efficiency. In this paper, A detection circuit of maximum power point of solar cell is described in this paper. And the performance evaluations for the photovoltaic power system of high efficiency are examined by the analysis of a new tracking controller with a maximum power $P_{max}$ detection of solar cell.