• 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 Satellite, Information and Communications
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• v.7 no.3
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• pp.135-139
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• 2012

A digital controller can simply realize a complex operation algorithm and power control process which can not be applied by an analog circuit for a solar array regulator(SAR). The digital resistive control(DRC) makes an equivalent input impedance of the SAR be resistive characteristic. The resistance of the solar array varies largely in a voltage source region and slightly in a current source region. Therefore when the solar array regulator is controlled by the DRC, the Advanced Incremental Conductance MPPT Algorithm with a Variable Step Size(AIC-MPPT-VSS) is suitable. The AIC-MPPT-VSS, however, using small signal resistance and large signal resistance of the solar array can not limit the absolute value of the solar array power. In this paper, the solar array power limiter is suggested and the BUCK-BOOST type SAR which is fully controlled by the digital controller is verified by simulation.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.10
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• pp.1432-1439
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• 2015

The solar array regulator supplies the electric power to the battery and the other units of a satellite by controlling the operating point of a solar array. In this paper, the solar array regulator composed with analog circuits is proposed. The solar array regulator has three modes. The first is a maximum power point tracking mode for harvesting the maximum photovoltaic power generation. The second is a power limitation mode which is designed for optimizing the volume and weight of the solar array regulator by preventing the excessive power conversion. The last constant voltage mode is proposed to keep the Li-Ion battery is not over-charge. The small signal model of the solar array regulator which has the reversed input and output variables in comparison with conventional converter is established and the stability is analysed. Finally, the proposed design of the solar array regulator is verified by experiments.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.4
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• pp.593-600
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• 2016

The solar array regulator for low earth orbit satellites controls a operating point of solar array for suppling electric power to the battery and the other units. Because the control object is reversed, the new approach for large and small signal analysis is needed despite using buck-converter for power stage. In this paper, the steady state analysis of solar array regulator is performed in continuous conduction mode and discontinuous conduction mode, and the border condition for each mode is established. Also, the small signal model of solar array regulator is established in discontinuous conduction mode. Experiments are carried on in worst condition which the solar array regulator can face with discontinuous conduction mode. The results show that the solar array regulator is in stable.

• Journal of Satellite, Information and Communications
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• v.9 no.3
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• pp.86-90
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• 2014

A DC-DC Converter operates in CCM(Continuous Coundcution Mode), DCM(Discontinuous Conduction Mode), CRM(Critical Conduction Mode). The CRM is boundary between CCM and DCM. If a DC-DC converter is designed to operate in CRM, its inductor volume can decrease and power loss which caused by switch and diode can decrease. In this paper, the DC-DC converter which operates in CRM is applied to a solar array regulator(SAR) for the satellite. The switching frequency of the CRM boost SAR changes according to input and output condition. The switching frequency limit logic is applied to limit the maximum switching frequency. Meanwhile, the small signal transfer function of the CRM boost SAR is simple, so the controller design is also simple. In this paper, the small signal transfer function from control reference to solar array voltage is induced. And the voltage controller is designed based on the small signal transfer function. Finally, the CRM boost SAR is verified by simulation.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2004.05a
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• pp.437-441
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• 2004

Recently, as the power capability of satellites increase, we need to develop a new SAR(Solar Array Regulator) with much higher power capacity whenever we design a power system of a new satelite. In this case, modular design method could be a good solution for this kind of problem. But when we use a modular method in the design of the parallelled converter, it is very important to share current equally between each module connected in paralled. In this paper, we study how to design the optimum current control-loop and voltage control-loop when we apply average current-mode control method to the parallel SAR. With the design results, we make a protype of the 3-module paralleling SAR and verify its performances.

• Aerospace Engineering and Technology
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• v.9 no.2
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• pp.176-184
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• 2010

The power simulator for a LEO satellite is a useful tool to analyze mission validity and energy balance for various mission scenarios by estimating power generation, power consumption, depth of discharge, bus voltage, charging/discharging current, etc. In this paper, it is described the calculation algorithm of the solar array (SA) power, the satellite load power and the battery modeling method to develop a satellite power simulation. To simulate the SA power generation, three different operation modes (DET, MPPT, CV) of SAR (Solar Array Regulator) are considered with a SA model. The satellite load power is estimated using the satellite unit power database, the unit on/off configuration at some satellite operation modes. The bus voltage and battery charging/discharging current at the specific DoD (Depth of Discharge) are calculated based on the battery characteristics. By this satellite power simulator, it can be conveniently analyzed the energy balance and the validity of a planned mission of a LEO satellite.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2004.11a
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• pp.255-258
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• 2004

The SAR(Solar Array Regulator) of KOMPSAT(Korea Multi Purpose SATellite)-1, 2 regulates a photovoltaic power according to the duty ratio commands of the ECU. But the ECU has so many other jobs that it can not calculate the solar array condition immediately. It means the SAR cannot always generate the maximum power of a photovoltaic. Nowadays, the commercial photovoltaic systems are using a controller operated by digital processing. But the usage for satellite is not adaptable. It is not easy to find the processor of the space grade and the price is expensive. So in this paper, the simple analog MPPT(Maximum Power Point Tracking) algorithm is proposed for the small satellite in LEO. This algorithm does not need any calculation of power by multiplication of voltage and current md a measurement of the solar array temperature. It is consist of only two sample and hold circuits, two comparators, a flip-flop, and an integrator. The proposed MPPT algorithm is verified by the simulation and experimental.

• Journal of Power Electronics
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• v.11 no.6
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• pp.870-879
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• 2011

Regulated peak power tracking (RPPT) systems such as the series structure and the series-parallel structures are commonly used in satellite space power systems. However, these structures process the solar array power or the battery power to the load through two cascaded regulators during one orbit cycle, which reduces the energy transfer efficiency. Also the battery charging time is increased due to placement of converter between the battery and the solar array. In this paper a parallel structure has been proposed which can improve the energy transfer efficiency and the battery charging time for satellite space power RPPT systems. An analogue controller is used to control all of the required functions, such as load voltage regulation and solar array stabilization with maximum power point tracking (MPPT). In order to compare the system efficiency and the battery charging efficiency of the proposed structure with those of a series (conventional) structure and a simplified series-parallel structure, simulations are performed and the results are analyzed using a loss analysis model. The proposed structure charges the battery more quickly when compared to the other two structures. Also the efficiency of the proposed structure has been improved under different modes of solar array operation when compared with the other two structures. To verify the system, experiments are carried out under different modes of solar array operation, including PPT charge, battery discharge, and eclipse and trickle charge.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.05a
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• pp.78-81
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• 2002

Printed Circuit Boards for satellite are composed of multi-layered copper plate and glass epoxy. Each copper layer have the complicated and different pattern to operate correctly for its mission. Especially. copper layer give effect on the PCB stiffness seriously. But It can make more complicate to predict the exact stiffness of PCB. In KOMPSAT-2 program, too many type of PCB are used for each electronic unit, and they have different type of pattern of copper layer. Solar array regulator has two type of PCB and it will be considered for this study. In this study. we calculate the PCB board stiffness of KOMPSAT-2 SAR unit considering the concept of simplified representative volume element. It will be correlated with the test results under KOMPSAT-2 vibration environmental condition to increase the reliability of this study.