Three-phase multilevel converter voltage quality bounds

Multilevel converters synthesize a staircase voltage waveform, resulting in a high voltage quality. Using a practical time domain approach, lower and upper bounds for voltage quality of three-phase multilevel converters are derived. The voltage quality bounds are introduced as closed-form analytical expressions for an arbitrary number of voltage levels and different modulation indices. They allow an analytical description of the behavior of multilevel converters. In comparison with PWM voltage quality, the lower and upper bounds may be useful for a fair classification of different switching methods and a first layout of multilevel converters.