“…In order to ensure that all transitions between adjacent voltage levels can be done through the low-voltage stage, only some state redundancy has to be included, and the maximum number of levels must be abandoned. Previous studies have either chosen to satisfy the modulation condition and, therefore, not to design the inverter with maximum number of levels; in this case, PWM control can be effectively considered as in [21], [26], [38], and [39]. Otherwise, when the dc sources selected to provide maximum number of levels, PWM control leads to high-voltage stage operating in high switching frequency as in [13] and [40].…”