• Proceedings of the KIPE Conference
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• 2012.11a
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• pp.103-104
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• 2012

In the AC module system, mismatch problem between AC power and constant input power is occurred. To solve this problem, electrolytic capacitor is utilized for diminishing power pulsation in PV side. However, it has disadvantages of low life span and weak in temperature. Decoupling method has been studied to reduce the capacitance and replaces electrolytic capacitor to film capacitor. This paper proposes design method for decoupling circuit which bidirectional DC-DC converter using soft switching. Proposed system is verified by design optimization and simulation results.

• Proceedings of the KIPE Conference
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• 2008.10a
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• pp.133-136
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• 2008

This paper presents a novel soft switching topology with resonant DC-DC converter and inverter. The resonant DC-DC converter consists of the auxiliary switch, resonant capacitor and inductor. All switches in the proposed topology is turn on at ZCS and turn off at ZVS operation. The proposed soft switching technology can be obtained the reduced switching losses and voltage and current stress of the power devices. Therefore, the resonant converter efficiency is higher than conventional boost converter. Simulation results on a 1kW soft switching converter are presented.

• New & Renewable Energy
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• v.1 no.2 s.2
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• pp.11-18
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• 2005

A modular photovoltaic PCS with high-frequency isolation is proposed. The proposed system consists of a SEPIC converter and a full-bridge inverter Using the power slope versus voltage of the PV array, the MPPT controller is proposed that produces a smooth transition to the maximum power point. The dc current of the PV array is estimated without using a dc current sensor The disturbance of the line voltage is detected using a fast sensing technique. Experimental results obtained on a 500W prototype show high performance such as almost unity power factor, $90\%$ power efficiency, $3.6\%$ THD.

• Journal of the Korean Solar Energy Society
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• v.32 no.spc3
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• pp.245-254
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• 2012

In photovoltaic system, the characteristics of photovoltaic module such as open circuit voltage and short circuit current will be changed because of cell temperature and solar radiation. Therefore, the boost converter of a PV system connects between the output of photovoltaic system and DC link capacitor of grid connected inverter as controlling duty ratio for maximum power point tracking(MPPT). This paper shows the dynamic characteristics of the boost converter by comparing single-loop and two-loop control algorithm using both analog and digital control. Both proposed compensation methods have been verified with computer simulation to demonstrate the validity of the proposed control schemes.

• Journal of Power Electronics
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• v.19 no.3
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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.

• Proceedings of the KIEE Conference
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• 1997.07f
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• pp.1942-1944
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• 1997

This paper presents a 10kW stand-alone photovoltaic power generation system with uninterruptible power system facility and its simple topology. The system s based on a DC/DC converter for a photovoltaic energy conversion, a four switch IGBT PWM inverter, a battery, and DSP controller.

• Proceedings of the KIPE Conference
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• 2004.07a
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• pp.133-136
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• 2004

Since the residential load is an AC load and the output of solar cell is a DC power, the photovoltaic system needs the DC/AC converter to utilize solar cell. In case of driving to interact with utility line, in order to operate at unity power factor, converter must provide the sinusoidal wave current and voltage with same phase of utility line. Since output of solar cell is greatly fluctuated by insolation, it is necessary that the operation of solar cell output in the range of the vicinity of maximum power point. In this paper, DC/AC converter is three phase PWM converter with smoothing reactor. And then, feedforward control used to obtain a superior characteristic for current control and digital PLL circuit used to detect the phase of utility line.

• The Transactions of the Korean Institute of Power Electronics
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• v.21 no.4
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• pp.335-342
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• 2016

This paper proposes an energy storage-assisted, series-connected module-integrated power conversion system that integrates a photovoltaic power conditioner and a charge balancing circuit. In conventional methods, a photovoltaic power conditioner and a cell-balancing circuit are needed for photovoltaic systems with energy storage devices, but they cause a complex configuration and high cost. Moreover, an imbalanced output voltage of the module-integrated converter for PV panels can be a result of partial shading. Partial shading can lead to the fault condition of the boost converter in shaded modules and high voltage stresses on the devices in other modules. To overcome these problems, a bidirectional buck-boost converter with an integrated magnetic device operating for a charge-balancing circuit is proposed. The proposed circuit has multiple secondary rectifiers with inductors sharing a single magnetic core, which works as an inductor for the main bidirectional charger/discharger of the energy storage. The secondary rectifiers operate as a cell-balancing circuit for both energy storage and the series-connected multiple outputs of the module-integrated converter. The operating principle of the cell-balancing power conversion circuit and the power stage design are presented and validated by PSIM simulation for analysis. A hardware prototype with equivalent photovoltaic modules is implemented for verification. The results verify that the modularized photovoltaic power conversion system in the output series with an energy storage successfully works with the proposed low-cost bidirectional buck-boost converter comprising a single magnetic device.

• Proceedings of the KIPE Conference
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• 2016.07a
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• pp.365-366
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• 2016

This paper presents a single-phase transformerless photovoltaic (PV) power converter systems based on the AC/DC boost inverter, which is capable of solving the leakage current and second-order ripple power issues. By eliminating the inherent ripple power in single-phase inverter, the bulky electrolytic capacitor can be replaced by a small film capacitor. The validity of the proposed scheme has been verified by the simulation results.

• The Transactions of the Korean Institute of Power Electronics
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• v.27 no.1
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• pp.63-73
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• 2022

The differential power processor (DPP) system is used to prevent a decrease in the total power generation due to the partial shading of photovoltaic modules. Compared with traditional series strings and full power processing (FPP) converter solutions, the DPP converter system shows advantages in terms of modularization process, volume, and transformation losses. However, the system has a limitation in that the power generation process of differential power processors produces lower power under certain irradiation conditions. This paper proposes a structure and operating algorithm for differential power processing modules that can use a single power converter for multiple strings. The operational algorithm for the differential power regulators allows the maximum power generation to be maintained in comparison with conventional series-connected and differential power processing methods even under various partial shading conditions. The operation algorithm of the proposed DPP is verified by Matlab/Simulink simulations.