Advanced Materials Research Vol. 768

Abstract: CuIn_0.8Ga_0.2Se₂ (CIGS) thin films have been successfully deposited on soda lime glass substrate at different working (Ar gas) pressures by Pulsed laser deposition (PLD). The effect of working pressure on the structural, electrical and optical properties of CIGS thin films has been investigated. All deposited CIGS thin films are found to be polycrystalline in nature with preferred orientation along (112). Crystallinity of CIGS thin films has been improved with decreasing of working pressures in PLD chamber. Stoichiometry of CIGS thin films has been maintained for all working pressures. Optical transmittance and electrical sheet resistance of CIGS thin films have been found to decrease with decrease of working pressure. The results of the present study signify that desired structural, electrical and optical properties of CIGS thin films can be obtained by changing the processing parameter in PLD method.Keywords: CIGS, XRD, Stoichiometry, UV-Vis-NIR spectrophotometer.

Abstract: A Split inductor is used with Exiting Inverter to interconnect inverter with grid connected system which avoids the usage of transformer. While using split inductor NPC-MLI shoot-through problems are producing in the bridge legs of an NPCTLI, its operation stability is ruined. Hysteresis Current Control (HCC) offers an excellent current control performance to NPCTLI. It acts based on the error current value i) and hysteresis band value (h). The proposed topology guarantees for no common-mode voltage, shoot-through possibility and capacitor balancing problem. Finally, the simulation results of a proposed SI-NPCTLI system verified using MATLAB SIMULINK.

Abstract: This paper proposes a hardware implementation of a resonant boost converter with photovoltaic system. The converter finds varied advantages like lower switching losses and increased efficiency. With the increased rate of energy crisis, the converter has paved a new way for solving the problem, in the recent years. The dc voltage source of the resonant boost converter is replaced by a photovoltaic system that energizes the converter. The renewable energy minimizes the fuel cost and highly decreases the maintenance cost. A PIC microcontroller is used to generate the pulses of the transistor switches in the boost converter and for the inverter circuit. Implementation of a low cost 16F877A microcontroller with a resonant boost photo voltaic system with higher efficiency and the experimental results has been tabulated. The performance of the circuit has been verified at different temperatures for different applications.

Abstract: In this paper, a hybrid multilevel inverter (MLI) with reduced number of components is modelled by deriving its source from solar PV array. The power switches of this MLI are controlled by utilizing the pulses derived by comparing the reference and carrier signal. The reference signal for the modulation process is based on 60 degree PWM. The carriers considered for the modulation process are triangular carrier wave and inverted sine carrier wave arranged in phase Disposition (PD) multicarrier method. The output voltage waveform of this hybrid MLI under consideration is analyzed with different performance parameters like Total Harmonic Distortion (THD), RMS Voltage, DC utilization Rate and harmonic spectrum. The simulation results show that the inverted sine based PD technique is yielding better performance than that of other technique. The above mentioned are examined with the help of MATLAB / SIMULINK.

Abstract: The growing population demands adequate supply of food grains for its sustenance and supporting life activities. The agricultural produce in India has increased over the years due to improved farm practices despite of which the country is ranked 2^nd in terms of the number of children suffering malnutrition. It is reported that the child mortality rate in the country due to hunger and sanitation is above 1,000 per day. The post harvest losses in India are estimated at 4 to 6 percent for food grains and 16 to 18 percent for fruits and vegetables occurring at various stages of harvesting, storage and processing. The post harvest remedies for the loss of food grains and other agricultural produce includes better post harvest storage techniques based on removal of moisture to store the produce without being perished. The crop drying techniques based on use of renewable energy offer succor to save the large agricultural produce that goes to drains without being consumed.The reported work deals with design of a solar crop dryer for drying based on solar Photovoltaic/ Thermal (SPV/T) techniqueKeywordsPost harvest losses, solar crop drying, solar PV/T systems,drying rate

Abstract: The project illustrates an idea of connecting the photovoltaic systems with the Grid, GCPS. In this work, the photovoltaic source of generation, the PVG is connected to the main electric grid via two static electronic stages. The first stage contains a buck-boost dc-dc converter, insuring impedance adaptation between PVG and grid. This converter is controlled by the Fuzzy Sliding Mode controller, FSMC. The controller is used to track the dc reference voltage which is used to satisfy the main grid. The second stage is composed of a dc bus and a three-phase voltage inverter, which serves as an interface to the PVG and the grid utility. The inverter output is regulated by means of suitable filters to inject the high quality Photovoltaic, PV power into the grid. The GCPS has been implemented in the MATLAB. The performances of the fuzzy sliding controller are compared to the results obtained by a sliding mode controller. The satisfactory simulation results, reduces the phenomenon of chattering. The resulting waveforms indicate the robustness of control against variation of the load and the source voltage of the converter.

Abstract: Copper tin sulphide (Cu₄SnS₄) thin films were prepared on glass substrates by the thermal co-evaporation technique by varying the source - substrate distance (SSD) in the range, 10 25 cm at a constant substrate temperature of 400°C. The influence of SSD on the chemical as well as physical properties of as-grown Cu₄SnS₄ films was investigated. The EDS analysis revealed that the evaporated films are stoichiometric at a SSD of 20 cm. X-ray diffraction analysis confirmed the presence of Cu₄SnS₄ phase in the layers following the orthorhombic crystal structure. The films showed a strong (311) peak as the preferred orientation. The evaluated crystallite size of the films decreased with the increase of SSD. From the SEM analysis, it was observed that needle like grains were distributed on the surface of the substrate and its size decreased with increasing SSD. The energy band gap was estimated using the optical transmittance data that varied in the range, 1.25 1.34 eV with the change of SSD.

Abstract: Fuel cell is one of the promising renewable and sustainable power sources because of its high power density and very low emission. In order to design a highly efficient fuel cell power system, a suitable DC-DC converter is required. In this paper, a four-phase directly coupled Interleaved Boost Converter (IBC) for fuel cell is proposed. A four-phase structure with interleaved control is proposed to reduce the input current ripples, the output voltage ripples, and the size of passive components with high efficiency compared with the other topologies. Mathematical analysis of overall current ripple, design of inductance and other components is investigated. Simulation study of the proposed converter interfaced with fuel cells is carried out using MATLAB. A prototype is built using MOSFET to validate the simulation results.

Abstract: The technology of harnessing wind energy through traditional three-bladed large wind turbines is in mature state. There are many disputes about the performance and availability of power output of the small wind turbines. The small wind turbines need improvement in technology for low speed starting behavior, enhancement in coefficient in performance, assured power output in low wind region. This work consists of development and field test performance of a non-conventional unidirectional co-axial two series rotors micro wind turbine to supply electricity for rural population. The unidirectional co-axial series rotor wind turbine consists of small rotors to replace a big rotor, mounted on a tilted long driveshaft at appropriate distances to face fresh wind, coupled to a direct drive generator. The developed turbine consists of two rotors, placed at suitable interval to avoid the wake effect. This work also includes field test performance and its analysis.

Abstract: This work proposes a lookup table based approach to track the maximum power from a solar photovoltaic (PV) module. The performance of the solar PV module is greatly influenced by various environmental factors and it is therefore necessary to operate the PV module at its optimal point so as to ensure that maximum power is extracted from the PV source. Several fixed step and variable step maximum power point tracking (MPPT) algorithms have been proposed in the literature. In this paper a simple and fast maximum power tracking method based on lookup table approach is proposed. The maximum power point voltages for various insolation levels are obtained from the experimental setup and are fed to the look up table. This look up table thus formulated can then provide the reference voltage for various insolation conditions without many computations. The performance of the proposed method is compared with that of the conventional MPPT methods like perturb and Observe (P&O), Incremental Conductance (INC) and Fuzzy logic (FLC) based MPPT. The simulation results show that the lookup table (LUT) approach tracks the maximum power point faster than the conventional algorithms under changing illumination conditions and reduces simulation time.