• 한국태양에너지학회:학술대회논문집
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• 2009.11a
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• pp.388-393
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• 2009

It is important to know character about efficiency of converters before manufacturing it. Recently, various techniques are developed for solar array system. Converters can be used for control of solar array's condition. So, solar array with converter structures are very useful. If we want to measure converter's efficiency after manufacturing it. It's not difficult if we have measuring equipment. But we need to measure efficiency before realization converters for development of optimized efficiency and simulations. This research offers an efficiency calculation of single phase hard switching boost converter. And it is the most basic type of converters. In fact, it can be used techniques for getting higher efficiency like soft-switching and more. But the cost is an important issue in compact solar array system. One way to escape from the cost problem is finding optimized efficiency of basic types of convener.

• Journal of Astronomy and Space Sciences
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• v.36 no.2
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• pp.69-74
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• 2019

Spacecraft requires sufficient power in orbit to perform its mission. So as to comply with system requirements, the sufficient power should be made by a solar cell array by photovoltaic power conversion. A life time of space program depends on its mission considering parts reliability and parts grade. Based on the mission life time, power equipment might be designed to meet specifications. In outer space, solar cell array might generate the dc power by photovoltaic conversion effects and GaInP/GaAs/Ge solar cells are used in this study. Space programs that require more than five years should select parts for high reliability applications. Therefore, reliability analysis for high reliability applications should be performed to check its fulfilment of the requirements. This program should also require more five years for its mission and we performed its analysis using parts count method (PCM) for its reliability. Finally, we performed reliability analysis and obtained quantitative figures found out 99.9%. In this study, we presented the reliability analysis of the 300 W GaInP/GaAs/Ge solar cell array.

• Journal of Power Electronics
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• v.17 no.2
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• pp.514-521
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• 2017

This paper proposes a shadowing compensation method for the solar modules of grid-connected photovoltaic generation systems. The shadowing compensator (SC) implemented by the proposed shadowing compensation method is used only for the solar modules that can be shaded by predictable sources of shading. The proposed SC can simplify both the power circuit and the control circuit as well as improve power efficiency and utilizes a voltage equalizer configured by a modified multi-winding fly-back converter. The proposed SC harvests energy from the entire solar cell array to compensate for the shaded sub-modules of the solar cell array, producing near-identical voltages of all shaded and un-shaded sub-modules in the solar cell array. This setup prevents the formation of multiple peaks in the P-V curve under shaded conditions. Hardware prototypes are developed for the SCs implemented by the conventional and modified multi-winding fly-back converters, and their performance is verified through testing. The experimental results show that both SCs can overcome the multiple peaks in the P-V curve. The proposed SC is superior to the SC implemented by the conventional multi-winding fly-back converter.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.47 no.12
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• pp.890-896
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• 2019

Due to the eccentricity of the Earth's orbit around the Sun and the obliquity of the Earth rotation axis against ecliptic frame, the apparent solar time differs from the mean solar time. Since the solar array of a GEO satellite makes a turn in mean solar day, the Sun pointing error of solar array is introduced over the year due to the equation of time. In this paper, efficient methods of compensating the equation of time to keep the solar array pointing the Sun are presented and verified with realistic simulation.

• Journal of the Korean Solar Energy Society
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• v.31 no.2
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• pp.120-127
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• 2011

Solar array has the following nonlinear characteristic, such as whose output current increases, output voltage is reduced. For this reason, boost converter with solar array system is always controlled to remain on the maximum power point of the solar array. In this case, we are not focused on the output of the solar array and not consider efficiency of the boost converter, which is assumed reliable. But efficiency of the converter also should be considered, which affects the total efficiency of the overall solar energy system. In this paper, efficiency calculation of the boost converter using power balance method is proposed, which will be used for a powerful reference before hardware realization.

• Journal of Satellite, Information and Communications
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• v.7 no.2
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• pp.72-75
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• 2012

A solar array makes a Solar Array Regulator (SAR) for Low-Earth-Orbit satellite have different small signal characteristic. Therefore, an Average-Current-Mode (ACM) controller cannot control the BUCK-BOOST type SAR which operates in a current region of the solar array. In this paper, we present the Pseudo-Continuous Current Mode (PCCM) BUCK-BOOST Type SAR which can be controller by the ACM Controller. We explain the circuit operation of the PCCM BUCK-BOOST Type SAR, derive its small signal transfer function and design ACM Controller. Finally, we verify the ACM control of the PCCM BUCK-BOOST Type SAR by using a simulation.

• Journal of Astronomy and Space Sciences
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• v.36 no.3
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• pp.181-186
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• 2019

The attitude information of spacecraft can be obtained by the sensors attached to it using a star tracker, three-axis magnetometer, three-axis gyroscope, and a global positioning signal receiver. By using these sensors, the spacecraft can be maneuvered by actuators that generate torques. In particular, electromagnetic-torque bars can be used for attitude control and as a momentum-canceling instrument. The spacecraft momentum can be created by the current through the electrical circuits and coils. Thus, the current around the electromagnetic-torque bars is a critical factor for precisely controlling the spacecraft. In connection with these concerns, a solar-cell array can be considered to prevent generation of a magnetic dipole moment because the solar-cell array can introduce a large amount of current through the electrical wires. The maximum value of a magnetic dipole moment that cannot affect precise control is $0.25A{\cdot}m^2$, which takes into account the current that flows through the reaction-wheel assembly and the magnetic-torque current. In this study, we designed a 300-W solar cell array and presented an optimal wire-routing method to minimize the magnetic dipole moment for space applications. We verified our proposed method by simulation.

• The Transactions of the Korean Institute of Power Electronics
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• v.25 no.2
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• pp.111-117
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• 2020

The photovoltaic module has the characteristic that the output power varies according to the amount of insolation. If partial shading occurs in an environment composed of an array, a number of local maximum power points (LMPPs) may be generated according to the shading state. Photovoltaic arrays require global maximum power point tracking due to variations in output characteristics caused by solar radiation and temperature. Conventional algorithms, such as P&O and Incond, do not follow the global maximum power point in a partial shaded solar array. In this study, we propose a technique to follow the global maximum power point by using the correlation of voltage, current, and power in solar arrays. The proposed control technique 2qw validated through simulation and experiments by constructing a 2-kW solar system.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.842-847
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• 2002

This research is concerned with ground experiments for satellite solar array deployment. The dynamic characteristics of the strain energy hinge is very important since it affects the shape and the speed of the solar array deployment. The rapid deployment results in overshoot and undesirable residual vibrations. The experimental results are in good agreement with theoretical results.

• Proceedings of the KIEE Conference
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• 1996.11a
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• pp.320-322
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• 1996

In this paper, solar array switching regulation is proposed as a replacement for conventional regulation techniques to reduce weight, thermal dissipation, and power system complexity for large power spacecraft. Each component model is developed which is used to explain the interaction of the solar array switching regulation and constant power type load, solar array.