Multilevel inverters use a different method to construct DC/AC inverters. This idea was published by Nabae in 1980 in an IEEE international conference, IEEE APEC’80 , and the same idea was published in 1981 in IEEE Transactions on Industry Application . Actually, multilevel inverters employ a different technique from the PWM method, which vertically chops a reference waveform to achieve the similar output waveform (e.g., a sine wave). The multilevel inverting technique horizontally accumulates levels to achieve the waveform (e.g., a sine wave).
The soft-switching technique has been implemented in DC/DC conversion for more than 20 years. We introduce this technique in DC/AC inverters in this chapter.