Synchronous space vector modulation based close loop flux control of a grid connected cascaded multilevel inverter

Asynchronous PWM technique for the inverter produces subharmonics and interharmonics. These harmonics lead to several undesired effects on grid connected applications. This necessitates the need for synchronous PWM. The close loop control of synchronous PWM is complex especially during dynamics. The PWM for multilevel inverter is fairly complicated as compared to two-level inverter. Hence, aforementioned problem is more severe when multilevel inverter is used as a voltage source inverter. To deal with these problems this paper proposes a scheme for the close loop flux control of a grid connected cascaded multilevel inverter. The scheme is based on synchronous space vector PWM. The usefulness of the proposed scheme is discussed, and demonstrated through analysis and experiments. The experimental results are shown for a laboratory prototype of cascaded 5-level inverter.