Mohsen Taherbaneh

Maximizing Output Power of a Solar Panel via Combination of Sun Tracking and Maximum Power Point Tracking by Fuzzy Controllers

In applications with low-energy conversion efficiency, maximizing the output power improves the efficiency. The maximum output power of a solar panel depends on the environmental conditions and load profile. In this paper, a method based on simultaneous use of two fuzzy controllers is developed in order to maximize the generated output power of a solar panel in a photovoltaic system: fuzzy-based sun tracking and maximum power point tracking. The sun tracking is performed by changing the solar panel orientation in horizontal and vertical directions by two DC motors properly designed. A DC-DC converter is employed to track the solar panel maximum power point. In addition, the proposed system has the capability of the extraction of solar panel curves. Experimental results present that the proposed fuzzy techniques result in increasing of power delivery from the solar panel, causing a reduction in size, weight, and cost of solar panels in photovoltaic systems.

Maximum Power Point Estimation for Photovoltaic Systems Using Neural Networks

Solar panels are the power sources in photovoltaic applications which provide electrical power. Solar panel characteristics depend on environmental conditions (solar radiation level, temperature and etc.). In this paper, estimation of maximum power point of silicon solar panels is presented. We applied two different neural networks (back propagation and RBF) for the purpose of estimation in different environmental conditions. These neural networks estimate Maximum power point of solar panels accurately. We used Matlab environment for the purpose of simulation, training and evaluation of these neural networks. It is shown that the responses of RBF neural network are faster and more accurate than back propagation.

Combination of Fuzzy-Based Maximum Power Point Tracker and Sun Tracker for Deployable Solar Panels in Photovoltaic Systems

Solar panels are power sources in photovoltaic applications. Solar panels I-V curves depend on environmental conditions such as irradiance, temperature, load and degradation level. In this paper, design and implementation of simultaneous fuzzy-based maximum power point tracker (MPPT) and sun tracker are presented for deployable solar panels. A digital controller was implemented by an AVR microcontroller. Results showed that the proposed system ensure to have photovoltaic system with higher efficiency. Finally, we observed that, using the proposed fuzzy-based MPP tracking and sun tracking simultaneously, solar panel output power can be remarkably increased leading in turn to reduction of the size, weight and cost of solar panels in photovoltaic systems.

Extracting best reliable scheme for Electrical Power Subsystem (EPS) of satellite

This paper describes the reliability comparison of different schemes connection for Electrical Power Subsystem (EPS) of satellite. EPS has to be able to provide sufficient power to the satellite subsystems under all possible satellite attitudes. There are eight schemes for EPS, which could be used for power supplying. In these schemes, two main system groups are Peak Power Tracking (PPT) and Direct Energy Transfer (DET) systems. Also in each system, we have four different connections which are Unregulated Bus Using Parallel Batteries, Unregulated Bus Using Linear Charge Current Control Recharge Control, Quasi-Regulated Bus with Constant Current Chargers and Systems Using a Fully Regulated Bus. In this paper we will compare the reliability of different schemes and will introduce the best reliable connection in these two systems for ESP.

Evaluation the Accuracy of One-Diode and Two-Diode Models for a Solar Panel Based Open-Air Climate Measurements

Increasingly, using lower energy cost system to overcome the need of human beings is of interest in todays energy conservation environment. To address the solution, several approaches have been undertaken in past. Where, renewable energy sources such as photovoltaic systems are one of the suitable options that will study in this paper. Furthermore, significant work has been carried out in the area of photovoltaic system as one of the main types of renewable energy sources whose utilization becomes more common due to its nature. On the other hand, modeling and simulation of a photovoltaic system could be used to predict system electrical behaviour in various environmental and load conditions. In this modeling, solar panels are one of the essential parts of a photovoltaic system which convert solar energy to electrical energy and have nonlinear I-V characteristic curves. Accurate prediction of the system electrical behaviour needs to have comprehensive and precise models for all parts of the system especially their solar panels. Consequently, it provides a valuable tool in order to investigate the electrical behaviour of the solar cell/panel. In the literature, models that used to express electrical behaviour of a solar cell/panel are mostly one-diode or two-diode models with a specific and close accuracy with respect to each other. One-diode model has five variable parameters and two-diode model has seven variable parameters in different environmental conditions respectively. During the last decades, different approaches have been developed in order to identify electrical characteristics of both models. (Castaner & Silvestre, 2002) have introduced and evaluated two separate models (one-diode and two-diode models) for a solar cell but dependency of the models parameters on environmental conditions has not been fully considered. Hence, the proposed models are not completely accurate. (Sera et al., 2007) have introduced a photovoltaic panel model based on datasheet values; however with some restrict assumptions. Series and shunt resistances of the proposed model have been stated constant and their dependencies on environmental conditions have been ignored. Furthermore, dark-saturation current has been considered as a variable which depend on the temperature but its variations with irradiance has been also neglected. Model equations have been merely stated for a solar panel which composed by several series cells.

A Fuzzy-Based Maximum Power Point Tracker for Body Mounted Solar Panels in LEO Satellites

Solar panels are the power subsystem components which provide satellite electrical power. Solar panels characteristics depend on environmental conditions (insolation level, temperature and etc.). In this paper, design and simulation of fuzzy-based MPPT for the body mounted solar panel in a LEO satellite are presented. To show how good the proposed technique is; we applied it into a real system. Simulation results show that the proposed fuzzy-based MPPT ensures a more generated power so that the size of solar panel can be decreased. We used Matlab-Simulink environment for the purpose of simulation. It is shown that if we use the proposed fuzzy-based MPPT, the size of solar panel can be remarkably reduced leading to reduction of the weight and cost of power subsystem in small LEO satellites.

A New Fuzzy-Based Maximum Power Point Tracker for a Solar Panel Based on Datasheet Values

Tracking maximum power point of a solar panel is of interest in most of photovoltaic applications. Solar panel modeling is also very interesting exclusively based on manufacturers data. Knowing that the manufacturers generally give the electrical specifications of their products at one operating condition, there are so many cases in which the specifications in other conditions are of interest. In this research, a comprehensive one-diode model for a solar panel with maximum obtainable accuracy is fully developed only based on datasheet values. The model parameters dependencies on environmental conditions are taken into consideration as much as possible. Comparison between real data and simulations results shows that the proposed model has maximum obtainable accuracy. Then a new fuzzy-based controller to track the maximum power point of the solar panel is also proposed which has better response from speed, accuracy and stability point of view respect to the previous common developed one.

A Trade-Off between the Efficiency, Ripple and Volume of a DC-DC Converter

In space qualified DC-DC converters, optimization of the following electrical characteristics is of greater interest in comparison with other specifications; power loss/efficiency, output voltage ripple and volume/weight. The main goal of this paper is to present an appropriate solution for optimizing the above mentioned characteristics. For this purpose, a comprehensive power loss model of a DC-DC converter is fully developed. Proper models are also demonstrated for assessment of the output voltage ripple and the utilized transformer volume as the bulkiest component in a DC-DC converter. In order to provide a test bed for evaluation of the proposed models, a 50W push-pull DC-DC converter is designed and implemented. Finally, a novel cost function with three assigned weight functions is proposed in order to have a trade-off among the power loss, the output voltage ripple and the utilized transformer volume of the converter. The cost function is optimized for applications in which volume has the highest priority in comparison with power loss and ripple. The optimization results show that the transformer volume can be decreased by up to 51% and this result is verified by experimental results. The developed models and algorithms in this paper can be used for other DC-DC converter topologies with some minor modifications.

Evaluation of two-diode-model of a solar panel in a wide range of environmental conditions

In this article, a standard and comprehensive two-diode model of a solar cell is first fully described, and a solar panel model based on this model is developed. A measurement system is designed and implemented to evaluate the validity of the developed model. This measurement system is capable of extracting the electrical behaviour of solar panels in different environmental conditions. A comparison between measurement data and simulation results is performed to evaluate the models accuracy. It is observed that the extracted electrical parameters have a good compatibility with the simulated data only near to nominal conditions. The main conclusion to be drawn is that the obtained model of a solar panel cannot fully describe its behaviour in a wide range of environmental conditions and consequently a modification is needed. Finally an appropriate method, using curve fitting, is introduced to modify the model. By adding several nonlinear terms to the equations of the solar panel model, the accuracy of the model is considerably boosted.

Power sources sizing in electrical power subsystem design based on orbit parameters change in LEO satellites

This paper intends to review and analyze the approach of power source sizing, which is an important step in Electrical Power Subsystem (EPS) design, based on change in orbit parameters. There are two main objectives for doing this research: 1) understanding the impacts of the orbital parameters change and the mechanisms of their interactions with the EPS design and operation, 2) evaluation of the importance of their effects. To this end, a typical LEO micro-satellite has been considered in different orbits, to investigate the impacts of variation in the main orbit parameters e.g. altitude and inclination angle. Then the sizing, operation and performance of power sources have been evaluated via comparing the results of in-orbit simulations of EPS operation. In addition, some indirect impacts of the orbit parameters change are evaluated, by analysis and calculation of the interaction between EPS and other subsystems. The results support and show how the sizing and operation of solar array and battery are under the influence of orbit parameters change via certain factors, such as orbit period, duration and the fraction of eclipse/sunlit phases, received solar irradiance by solar panels, and received thermal fluxes from the Sun. According to the acquired results, any altitude increment leads to have better margins in power source sizing but there is an optimum value for inclination angle from this point of view.