الفهرس 
Introduction and Historical Review
Solar Photovoltaic SystemOnly 14 pages are availabe for public view
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Abstract
The aim of the present thesis is to shed further light on performance improvement of the renewable energy conversion systems. In this respect, extensive studies were conducted concerning a set of experimental trails, theoretical calculations and computer simulations using National Instrument Multisim program version 12.0 for designing, implementing, operating and evaluating the efficiency of the investigated systems. In this concern, the photovoltaic -and wind turbine - systems were used as examples for the renewable energy sources. For the solar energy conversion, the DC-DC boost converter system was investigated. While, the AC-DC boost converter system was considered for the wind energy conversion.
Considering the DC-DC boost converter system, a 5/24.4 VDC boost converter operating in the discontinuous conduction mode was investigated, where its design, implementation, operation and efficiency evaluation were reported. The improvement procedures were carried out including components selection (active and passive) and circuit design (RC-snubber and RC-filter circuit). In this concern, DC output-voltage, current and power, conversion efficiency and the parasitic voltage ripples which superimposed on the output voltage waveforms were studied. Besides, at the switch node of the boost converter system the ringing frequency, peak voltage and the equivalent parasitic impedance during Turn-On, as well the spike voltage during Turn-Off was investigated.
It was concluded that, the output voltage of the DC-DC boost converter reached the value of 23.5 Volts which is approximately 96.3 % of the theoretical value with voltage ripple amplitude of 160 mV when using the active components: MOSFET type STP36NF06, Schottky diode type MBRS130LT3G, as well the pasive component: boost inductor type 14433445C. As well, the input-and out-capacitances value were 4.7 mF.
The study was extended to include RC-snubber circuit for reducing the parasitic ringing at the switch node. Where, it was found that, the ringing frequency decayed from 427.5 kHz and 11.8 Volts down to a single pulse with a peak value of 5.6 Volts and disappeared after 6.8 μs.For reducing the amplitude and frequency of the voltage ripple, RC-filter circuit was designed, which leads their values to be stepped down from 160 mV and 2.0 kHz down-to-around 60 mV and 0.499 kHz, respectively.
For reducing the amplitude and frequency of the voltage ripple, RC-filter circuit was designed, which leads their values to be stepped down from 160 mV and 2.0 kHz down-to-around 60 mV and 0.499 kHz, respectively.
Concerning the AC-DC boost converter, two configutations were considered: two stages AC-DC (bridge rectifier and DC-DC boost converter) and single stage AC-DC (DC-DC boost converter parallel with DC-DC buck-boost converter) were investigated. For the two configurations, the DC output-voltage, current and power, besides the conversion efficiency and the parasitic voltage ripple were studied. Moreover, at the switch node of the system the parasitic electrical parameters; ringing frequency, peak voltage and the equivalent parasitic impedance during Turn-On, as well the spike voltage during Turn-Off were investigated.
For the two stages AC-DC boost converter configuration with an AC input voltage of 7.85 Volts and DC output voltage of 24.4 Volts, the design, implementation, operation and its efficiency evaluation were investigated. The efficiency improvement was based upon both bridge rectifier selection and RC-filter circuit design.
The system design which based on bridge rectifier circuit was equipped with different diodes (PN junction, fast recovery and Schottky -silicon diodes). It was found that, the DC output voltage of the two stages AC-DC boost converter system based on Schottky diode bridge rectifier reached the value of 22 Volts which is approximately 90.16 % of the theoretical value.
- For RC-filter circuit, it was found that the amplitude and frequency of the voltage ripple were stepped down from 600 mV and 2.0 kHz down-to-around 200 mV and 0.6 kHz, respectively.
Considering the single stage AC-DC boost converter configuration with an AC input voltage of 7.85 Volts and DC output voltage of 24.4 Volts,the design, implementation, operation and its efficiency evaluation were investigated. It was found that, the DC output voltage reached the value of 23.4 Volts which is approximately 95.9 % of the theoretical value, which is mainly attributed to the lower conduction loss due to decreasing power switches numbers. Finally, RC-filter circuit was designed for reducing the amplitude and frequency of the voltage ripples. It was found that, their values were stepped down from 160 mV and 2.0 kHz down-to-62 mV and 0.498 kHz, respectively.
Finally, from the simulation and experimental work, it was proved that the proposed boost converter system operates properly as a DC-DC converter in the input voltage range from 3.36 up-to7.3 Volts. While it operates properly as an AC-DC converter in the input voltage range from 5.0 up-to 10 Volts.