Dead-time effect and compensations of three-level neutral point clamp inverters for high-performance drive applications

Due to the use of high-power devices and slow-switching frequency in a thre e-level neutral point clamp inverter, the dead-time effect may not be compe nsated sufficiently fast by using methods developed for the two-level inver ter. In this paper, the dead-time effect in a three-level inverter with snu bber circuits is analyzed to reveal that it does not only depend on load cu rrent direction, but also on magnitude. The snubber network also plays an i mportant role in determining the output phase voltage during the dead-time period. Software techniques are proposed to compensate the dead-time effect as soon as it occurs as demanded by the slow-switching frequency. Experime ntal results show their effectiveness.