PV fed grid connected multilevel inverter with space vector control having over modulation

The three-phase grid-connected converter is widely used in renewable and electric power system applications. In general, two power conversion stages are required when low voltage unregulated PV output is conditioned to generate AC power. This report presents a space vector algorithm for a 3 level diode clamped multilevel inverter for operation in over modulation range. This type of inverter has several advantages over standard two level voltage source inverter, such as greater number of levels in output voltage waveforms, lower dv/dt, less harmonic distortion in voltage and current waveforms and lower switching frequencies. The operation of multilevel inverter in both stand alone and grid connected mode is discussed. The stand-alone mode multilevel inverter is controlled to provide voltage of desired magnitude and frequency to local loads. In grid connected mode multilevel inverter operates in current controlled mode to supply pre-defined active power to the grid. This report presents a SVPWM algorithm with over modulation for three level based on standard two level SVPWM. The presented scheme is described clearly and hardware results are reported to demonstrate its effectiveness.