This article reviews the fundamentals of multilevel multiphase neutral-point-clamped DC–AC power converters. These converters are configured with one or more legs and a common DC-link. Each leg is functionally equivalent to a single-pole multiple-throw switch (n¿=¿3 positions) and it is implemented with a combination of only power semiconductor devices. The main leg topologies are initially presented, both active(transistor) clamped and passive(diode) clamped, for any number of levels. The leg switching states enabling all possible leg positions are subsequently discussed. Then, the set of all possible converter switching states and their standard representation in the converter space vector diagram is systematically derived, starting from the simplest converter (single-phase single-leg) up to the most complex converter with an arbitrary number of phases. The space vector diagram is illustrated for three-, four-, and n-levels in the usual single-phase and three-phase cases. Once the converter states have been characterized, the most common converter control approaches are introduced on the basis of the space vector diagram, including space vector control, space vector modulation, programmed pulse width modulation, hysteresis control, and predictive control. These control strategies are illustrated in simple and conventional DC–AC converter configurations. Finally, the article discusses the DC-link capacitor voltage balance problem, which is inherent to these topologies whenever the DC-link is configured with a capacitive voltage divider. The basics of the different solutions to guarantee the balancing are presented, both through the inclusion of additional hardware and through the application of a suitable converter control strategy
