16-10-2014, 09:53 AM
Abstracts: Nowadays in many application we require pure ac distortion less sinusoidal waves to drive any device. But, its difficult to obtain pure sinusoidal waves using conventional converters. Basically, we use multilevel inveters to obtain pure ac sine wave which makes our circuit very ,much complex and hard to control. So, its identical to design appropriate controlled inverter to obtain pure sinusoidal waves with least distortion. This project is the modification of conventionally used inverters of 180 & 120 degree gate control. In which we have involved widely used PWM technique to get minimum distortion during conversion. In this method each MOSFET conduct 150 degree instead of 180 & 120 degree. As a result, we will get more harmonic elimination with respect to conventional inverters. This project presents a new modification and implementation for the most common, simple and well-known three-phase converter. In this strategy, each one of the six MOSFETs conducts for 150 degree instead of the known 180 degree or 120 degree conduction modes and this 150 degree conduction was get through using a AT89C51 Microcontroller, resulting in a wye connected load, the output phase voltage becomes a seven-level, 12 steps waveform. In these 150 degree conduction-modes, controlling strategy is controlling very simply through the AT89C51 Microcontroller and MOSFETs. Hardware of three phase voltage source inverter in 150 degree conduction mode output voltages results was got same as a simulation results. So the using the new controlling strategy, this result a more reduction of the total harmonic distortion is obtained and simplicity of hardware compare to 180 degree and 120 degree conduction modes. Simulation and experimental results show the contribution of the proposed strategy. Simulation is done Mat Lab.