Computer simulation and experimental implementation of single phase power inverters regarding output waveforms

Recent rises in electrical energy costs have done alternative energy options more attractive. A device such as solar panel is able to convert photons from the sun into the DC (Direct Current) electric which can be used by the end users. However, there is a problem by using this kind of energy. Our electric grid and most of the house appliances are based on the AC (Alternating Current) electric so the energy achieved by the sun or wind power needs to be converted from DC to AC to be useful. This converting process is done by an electronic device called inverter. Inverters can be found in a wide area of power electronics in the industry. The produced output voltage and frequency at the AC side of an inverter depend on the circuit structure, transformers and applied components. In this thesis, comparative analysis of single phase power inverters regarding their output waveforms was performed. Square wave, modified square wave and true sine wave inverter circuits were designed and analyzed using Proteus Professional package program. This comparison was fulfilled with respect to the circuit configuration, THD (Total Harmonic Distortion) and output efficiency. After simulation results these inverter circuits were realized on PCB (Printed Circuit Board) circuits. Efficiency of the inverters was calculated using Extech true RMS digital multimeter and THD values were measured by means of the Fluke 435 Power Analyzer device. According to the simulation and experimental results, the analyzed square wave inverter circuit has about 55% THD and 45% efficiency due to the circuit structure. The analyzed modified square wave inverter circuit has about 38% THD and 60% efficiency better than square wave inverter. The analyzed true sine wave inverter circuit having with about 10% THD and an efficiency of 75% has the most ideal output signal among the inverter types. Tests on resistive and inductive loads were carried out under laboratory conditions and output signals were observed with the help of Tektronix digital storage oscilloscope. Test results and simulation outcomes were confirmed to each other. It was found out that true sine wave inverter circuit is better and more efficient in many aspects compared to the modified and square wave inverter circuits in spite of their complicated structures and higher costs.