• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.12
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• pp.6006-6012
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• 2012

General solar street light system needs two separate power supply for charging the battery and driving LED Lamp. In this study, one power supply is used for both charging battery and driving LED lamp. In particular, in order to increase the efficiency of the equipment, (maximum power point tracking: MPPT) was applied which is widely adopted in grid-connected solar systems. LED driver embodied using current control routine of charger into Essential constant current system.

• The Transactions of the Korean Institute of Power Electronics
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• v.12 no.5
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• pp.355-363
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• 2007

In this paper, the transformerless three-phase line-connected PV PCS (photovoltaic power conditioning system) is proposed. An improved P&O (perturb and observe) MPPT (maximum power point tracking) algorithm that prevents local maximum power point tracking is proposed. By controlling the three-phase line-connected voltage source inverter using outer DC-link voltage controller, inner current controller and microcontroller friendly simplified space vector modulation (SVM) method, a unity power factor is achieved. An algorithm is suggested to control the DC-link voltage faster and more correctly for the increase system stability and power factor. All algorithms and controllers are implemented on a single-chip microcontroller and the superiority of the proposed algorithms and controllers is proved by experiments.

• Journal of Power Electronics
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• v.10 no.1
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• pp.79-84
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• 2010

This paper presents a grid connected photo-voltaic system using a quasi-Z-source inverter (QZSI) for power stage reduction. The power stage can be reduced because of an additional shoot-through stage which is a characteristic of QZSI. Therefore, by utilizing a QZSI the system's efficiency can be increased. In this paper, for applying a QZSI to a PV system, control methods such as maximum power point tracking (MPPT), point of common coupling (PCC) current control and PWM are studied and verified through simulation and experiment. In order to explain the above controllers, the characteristics of a QZSI are first analyzed. Then the MPPT control technique with a modified P&O method, the PCC current control for the regulation of the dc-link capacitor voltage and the PWM methods for the proposed system are explained. The feasibility of the proposed algorithm is verified through simulation and experiment with a 3kW system.

• Journal of IKEEE
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• v.22 no.2
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• pp.460-475
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• 2018

In the variable-speed wind energy system, to achieve maximum power point tracking (MPPT), the wind turbine should run close to its optimal angular speed according to the wind speed. Non-linear control methods that consider the dynamic behavior of wind speed are generally used to provide maximum power and improved efficiency. In this perspective, the mechanical power is estimated using Kalman filter. And then, from the estimated mechanical power, the wind speed is estimated with Newton-Raphson method to achieve maximum power without anemometer. However, the blade shape and air density get changed with time and the generator efficiency is also degraded. This results in incorrect estimation of wind speed and MPPT. It causes not only the power loss but also incorrect wind resource assessment of site. In this paper, the adaptive maximum power point tracking control algorithm for wind turbine system based on the estimation of wind speed is proposed. The proposed method applies correction factor to wind turbine system to have accurate wind speed estimation for exact MPPT. The proposed method is validated with numerical simulations and the results show an improved performance.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.5
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• pp.72-79
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• 2009

Solar energy is desirable due to its renewable and pollution-free properties. In order to utilize the present utility grid infrastructure for power transmission and distribution, a do-dc boost converter and grid connected dc-to-ac inverters are needed for solar power generation. The dc-dc boost converter allows the PV system to operate at high do-link voltage. The single-phase inverter provides the necessary voltage and frequency for interconnection to the grid. In this paper, first, current loop transfer function of a single-phase grid-tie inverter has been systematically derived Second the MPPT of conductance increment method at converter side is proposed to supply the maximum power to the inverter side. Simulation results are shown to access the performance of PV system and its behaviour at the interconnection point.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2008.05a
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• pp.407-410
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• 2008

This paper presents a maximum power point tracking(MPPT) of photovoltaic system with duty ratio of DC-DC converter considered load. A variation of solar irradiation is most important factor in the MPPT of PV system That is nonlinear, aperiodic and complicated. NN was widely used due to easily solving a complex math problem. The paper consists of solar radiation source, DC-DC converter, DC motor and load(cf, pump). NN algorithm apply to DC-DC converter through an adaptive control of neural network, calculates converter-duty ratio using an adaptive control of NN. The results of an adaptive control of NN compared with the results of converter-duty ratio which are calculated mathematical modeling and evaluate the proposed algorithm. The experimental data show that an adequacy of the algorithm was established through the compared data.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.10a
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• pp.189-192
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• 2008

This paper introduces the photovoltaic(PV) simulator for the inverter of PV energy system. In order to embody the PV simulator, the conventional solar cell is numerically modeled based on the one-diode equivalent circuit. With the P-V relationships, we find the maximum and minimum power which is needed during the inverter performs the MPPT algorithm and design the parameter based on the maximum and minimum power. Finally, this paper verifies design parameters numerically through the PSIM and analyzes the PV simulator in the frequency domain using Matlab.

• Journal of Power Electronics
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• v.16 no.2
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• pp.666-674
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• 2016

In this paper, a high efficiency satellite electrical power supply system is proposed. The increased efficiency of the power supply system allows for downscaling of the solar array and battery weight, which are among the most important satellite design considerations. The satellite power supply system comprises two units, namely a generation unit and a storage unit. To increase the efficiency of the solar array, a maximum power point tracker (MPPT) is used in the power generation unit. In order to improve the MPPT performance, a novel algorithm is proposed on the basis of the hill climbing method. This method can track the main peak of the array power curve in satellites with long duration missions under unpredicted circumstances such as a part of the array being damaged or the presence of a shadow. A lithium-ion battery is utilized in the storage unit. An algorithm for calculating the optimal rate of battery charging is proposed where the battery is charged with the maximum possible efficiency considering the situation of the satellite. The proposed system is designed and manufactured. In addition, it is compared to the conventional power supply systems in similar satellites. Results show a 12% increase in the overall efficiency of the power supply system when compared to the conventional method.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11b
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• pp.153-156
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• 2001

Maximum Power Point Tracking(MPPT) is used in wind power generation systems to maximize wind power turbin output power, irrespective of wind speed conditions and of the load electrical characteristics. In this paper we do the equivalent modeling the mechanical energy of wind power turbine according to wind speed into the synchronous generator. We analyse the equivalent modeling output part of rectifier into DC/DC converter input part theoretically. We design a control algorithm for variable voltage according to wind speed intensity and density so that load voltage of chopper is controlled steadily using the maximum power point tracking (MPPT) control method. We analyse a battery charging characteristics and a charging circuit for power storage enabling the supply of stable power to the load. We design a system and do the modeling of it analytically so that it supplies a stable power to the load by constructing a DC-AC inverter point. Also we design a charging circuit usable in actual wind power generation system of 30kW and confirm its validity.

• Proceedings of the KIPE Conference
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• 2010.07a
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• pp.93-94
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• 2010

This paper proposes maximum power point tracking(MPPT) control algorithm of PV system using a novel method. The proposed hybrid method is composed perturb and observe (PO) method and constant voltage(CV) method. PO method is simple to realize and CV method is possible to tracking MPP with low insolation. Response characteristics of proposed algorithm is compared to conventional PO method with insolation variation. This paper proves the validity of proposed algorithm through the analysis result.