Design and optimum sizing of multiple pulse width modulation (MPWM) inverter based on solar radiation in Kangar, Malaysia

Solar energy is one of the renewable energy, it is a fusion process of the sun that produces solar irradiation and reaches the surface of earth. The study of solar irradiation in one area of the earth surface is very important. The daily, monthly and annual data collections of solar irradiation are useful in giving information for a particular area that it is suitable or not to develop a photovoltaic (PV) power generation, especially for a PV powered inverter system application. Many inverters have been developed, but they still uses transformer and their output voltage waveform is not sinusoidal which causes the low efficiency and it is relatively expansive. Furthermore, the PV powered inverters only depend on PV power source and they are not considered to be optimized in the their operation, thus they can fail in operation if no solar irradiance and the system is not optimum in term of number of PV module. This thesis presents the daily, monthly and annual solar irradiation in Kangar, Malaysia. They are observed and analyzed for the potential of multiple pulse width modulation (MPWM) transformerless PV inverter (TPVI) system application. It is due to the MPWM TPVI system is operated directly by PV module and integrated by DC-DC boost converter, therefore a DC source change controller is developed and an optimization sizing of the system is studied in this thesis. A MPWM TPVI system is constructed by four main circuits, namely PV voltage storage circuit, pulse driver circuit, full bridge circuit and LC circuit. The AC output voltage waveform of MPWM TPVI system is sinusoidal that it is driven by microcontroller PIC 16F877A in the full bridge circuit. The DC-DC boost converter is designed for the output power of 1200 W and it is controlled by PID controller and PWM technique to stable its output voltage as input voltage of the MPWM TPVI. Whereas, the DC source change controller is designed using microcontroller PIC 16F877A to detect the voltage level of PV module and to change to the other DC source. According to data of the solar radiation throughout the year 2015, the average monthly solar radiation for the year of 2015 is 407.0 W/m2 or 4861.44 Wh/m2. It is classified as a very high solar radiation, the sky in Kangar is very clear and it is suitable for generating the MPWM TPVI system with its output voltage waveform is sinusoidal. The MPWM TPVI system is designed by using MOSFET IRFP 450 and LC filter that can flows the current of 5 A. The MPWM TPVI AC voltage is 240 V with unity power factor, therefore it has maximum capability power is 1200 W. The output voltage and power of DC-DC boost converter can achieve a value that required by the MPWM TPVI system. If the DC source change controller detects the output voltage of PV module falls below 190 V, it will change the input source to the DC rectifier circuit. The optimum PV module string number is 21 (difference between the generated power and demanded power is zero). It is due to there is three PV modules in one string that connected in series, therefore the total number of PV module is 63 to generate the 1200 W MPWM TPVI system.