• 전력전자학회:학술대회논문집
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• 전력전자학회 2019년도 전력전자학술대회
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• pp.11-13
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• 2019

This paper proposes a novel high step-up non-isolated DC-DC converter, suitable for regulating dc bus in various inherent low voltage micro sources especially for photovoltaic (PV) and fuel cell sources. This novel high voltage Non-isolated Boost DC-DC converter topology is best replacement, where high voltage conversion ratio is required without the transformer and also need continuous input current. Since the proposed topology utilizes the stack-based structure, the voltage gain, and the efficiency are higher than other conventional non-isolated converters. Switches in this topology is easier to control since its control signal is grounding reference. Also, there is no need of extra gate driver and extra power supply for driver circuit, which reduces the cost and size of system. In order to show the feasibility and practicality of the proposed topology principle operation, steady state analysis and simulation result is presented and analyzed in detail. To verify the performance of proposed converter and theoretical analysis 360W laboratory prototype is implemented.

• Journal of Power Electronics
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• 제19권3호
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• pp.665-675
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• 2019

Renewable energy based on photovoltaic systems is beginning to play an important role to supply power to remote areas all over the world. Owing to the lower output voltage of photovoltaic arrays, high gain DC-DC converters with a high efficiency are required in practice. This paper presents a novel interleaved DC-DC boost converter with a high voltage gain, where the input terminal is interlaced in parallel and the output terminal is staggered in series (IPOSB). The IPOSB configuration can reduce input current ripples because two inductors are interlaced in parallel. The double output capacitors are charged in staggered parallel and discharged in series for the load. Therefore, IPOSB can attain a high step-up conversion and a lower output voltage ripple. In addtion, the output voltage can be automatically divided by two capacitors, without the need for extra sharing control methods. At the same time, the voltage stress of the power devices is lowered. The inrush current problem of capacitors is restrained by the inductor when compared with high gain converters with a switching-capacitor structure. The working principle and steady-state characteristics of the converter are analyzed in detail. The correctness of the theoretical analysis is verified by experimental results.

• Journal of Power Electronics
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• 제16권6호
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• pp.2005-2015
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• 2016

A high-step-up DC/DC converter for renewable energy systems is proposed. The proposed structure provides high voltage gain by using a coupled inductor without the need for high duty cycles and high turn ratios. The voltage gain is increased through capacitor-charging techniques. In the proposed converter, the energy of the leakage inductors of the coupled inductor is reused. This feature reduces the stress on the switch. Therefore, a switch with low ON-state resistance can be used in the proposed converter to reduce losses and increase efficiency. The main switch is placed in series with the source. Therefore, the converter can control the energy flow from the source to the load. The operating principle is discussed in detail, and a steady state analysis of the proposed converter is conducted. The performance of the proposed converter is verified by experimental results.

• Journal of Power Electronics
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• 제19권3호
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• pp.645-654
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• 2019

In this paper, a new high step up DC/DC converter with a modified super-lift technique is presented. The coupled inductor technique is combined with the super-lift technique to provide a tenfold or more voltage gain with a proper duty cycle and a low turn ratio. Due to a high conversion ratio, the voltage stress on the semiconductor devices is reduced. As a result, low voltage ultra-fast recovery diodes and low on resistance MOSFET can be used, which improves the reverse recovery problems and conduction losses. This converter employs a passive clamp circuit to recycle the energy stored in the leakage inductance. The proposed convertor features a high conversion ratio with a low turn ratio, low voltage stress, low reverse recovery losses, omission of the inrush currents of the switch capacitor loops, high efficiency, small volume and reduced cost. This converter is suitable for renewable energy applications. The operational principle and a steady-state analysis of the proposed converter are presented in details. A 200W, 30V input, 380V output laboratory prototype circuit is implemented to confirm the theoretical analysis.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 추계학술대회 논문집
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• pp.289-292
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• 2007

The modular line-connected photovoltaic PCS (power conditioning system) is proposed. The proposed system consists of a step-up DC-DC converter and a full-bridge inverter. A step-up DC-DC converter using a dual series-resonant rectifier circuit and a active-clamp circuit is proposed to achieve a high efficiency and a high input-output voltage ratio efficiently. An IncCond (incremental conductance) MPPT (maximum power point tracking) algorithm that improves MPPT characteristic is used. By control a inverter using a linearized output current controller, a unity power factor is achieved. All algorithms and controllers are implemented on a single-chip microcontroller and the superiority of the proposed algorithms and controllers is proved by experiments.

• 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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• 제16권5호
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• pp.1629-1638
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• 2016

Differential power processing (DPP) systems are among the most effective architectures for photovoltaic (PV) power systems because they are highly efficient as a result of their distributed local maximum power point tracking ability, which allows the fractional processing of the total generated power. However, DPP systems require a high-efficiency, high step-up/down bidirectional converter with broad operating ranges and galvanic isolation. This study proposes a single, magnetic, high-efficiency, high step-up/down bidirectional DC-DC converter. The proposed converter is composed of a bidirectional flyback and a bidirectional isolated switched-capacitor cell, which are competitively cheap. The output terminals of the flyback converter and switched-capacitor cell are connected in series to obtain the voltage step-up. In the reverse power flow, the converter reciprocally operates with high efficiency across a broad operating range because it uses hard switching instead of soft switching. The proposed topology achieves a genuine on-off interleaved energy transfer at the transformer core and windings, thus providing an excellent utilization ratio. The dynamic characteristics of the converter are analyzed for the controller design. Finally, a 240 W hardware prototype is constructed to demonstrate the operation of the bidirectional converter under a current feedback control loop. To improve the efficiency of a PV system, the maximum power point tracking method is applied to the proposed converter.

• Journal of Power Electronics
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• 제15권1호
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• pp.86-95
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• 2015

An active clamp high step-up boost converter with a coupled inductor is proposed in this paper. In the proposed strategy, a coupled inductor is adopted to achieve a high voltage gain. The clamp circuit is included to achieve the zero-voltage-switching (ZVS) condition for both the main and clamp switches. A rectifier composed of a capacitor and a diode is added to reduce the voltage stress of the output rectifier diode. As a result, diodes with a low reverse-recovery time and forward voltage-drop can be utilized. Since the voltage stresses of the main and clamp switches are far below the output voltage, low-voltage-rated MOSFETs can be adopted to reduce conduction losses. Moreover, the reverse-recovery losses of the diodes are reduced due to the inherent leakage inductance of the coupled inductor. Therefore, high efficiency can be expected. Firstly, the derivation of the proposed converter is given and the operation analysis is described. Then, a steady-state performance analysis of the proposed converter is analyzed in detail. Finally, a 250 W prototype is built to verify the analysis. The measured maximum efficiency of the prototype is 95%.

• 전기전자학회논문지
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• 제16권4호
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• pp.335-342
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• 2012

본 논문에서는 고효율과 고역률을 위한 새로운 DCM-ZVS 스텝 업-다운 AC-DC 컨버터에 대해 연구된다. 제안한 DCM-ZVS 컨버터에 사용된 스위칭 소자들은 새로운 유사공진 회로에 의해 소프트 스위칭 기법으로 동작되고, 펄스폭변조(PWM) 방식에 의한 전류불연속모드(DCM)로 구동된다. 제안한 컨버터의 유사공진 회로는 스텝 업-다운 인덕터와 무손실 스너버 커패시터로 구성되고, 또한 DCM에 의해 제어회로 기법과 제어회로 구성이 간단한 장점이 주어진다. 입력 교류 전류파형은 일정 스위칭 주파수에 의한 교류 입력전압의 크기에 비례한 유사 정현파형으로 된다. 그 결과, 제안한 DCM-ZVS 컨버터는 낮은 스위칭 손실과 고효율을 얻을 수 있으며, 컨버터의 입력역률은 거의 단위역률로 된다. 해석적 결과의 타당성은 다양한 컴퓨터 시뮬레이션과 실험 결과를 통해 입증된다.

• 대한인간공학회지
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• 제28권3호
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• pp.95-102
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• 2009

Ten young females were participated in this study to investigate the effects of types of shoes (sneakers, high heels, kill heels), types of tasks (standing, walking floor, step up and down), and areas of foot (fore foot, middle foot, rear foot) on foot pressures as well as subjective discomfort ratings. Results showed that kill heels had the most discomfort shoes, followed by high heels and sneakers. Generally, as the heel was higher, the discomfort of foot increased. For the analyses of task types, generally discomfort ratings were highest for the step down and up, followed by walking floor and standing. Especially discomfort ratings of high heels and kill heels were more evident in case of step up and step down than standing and walking floor. Standing task was rated as the lowest levels of discomfort on users' foot. Peak and mean foot pressures were also evaluated in this study. The findings represented that there was no significant differences between types of shoes in both peak and mean foot pressures. The peak pressure (82.14kPa) and mean pressure (40.32kPa) for standing task were significantly lower than those of other tasks [walking floor (190.55kPa, 55.46kPa), step up (191.43kPa, 53.80kPa), and step down (200.66kPa, 52.62kPa)]. Generally discomfort ratings and peak/mean pressures associated with foot showed that fore foot had higher discomfort ratings as well as peak and mean pressures than middle and rear foots. In particularly, this trend was more obvious in case of high heels and kill heels. For the high heels and kill heels, the peak pressures of fore foot were 4.5~4.8 times and 2.3~2.5 times greater than that of middle foot and rear foot, respectively, whereas the peak pressures of fore foot were 2.9 times and 1.7 times greater than that of middle and rear foots, respectively, in case of sneakers.