Switching State Sequences-Based Modulation Scheme for T-Type 5L-ANPC Converter

A switching state sequences (SSSs)-based modulation scheme along with a dead-time effect compensation method is proposed in this paper. In the proposed modulation scheme, the converter's switching states changing sequence in one carrier period, i.e., the SSS, is treated as the basic unit to control the T-type 5L-ANPC converter. Because there are only two possible voltage levels in each SSS, the converter can be controlled as a traditional two-level converter within each SSS. Thus, a switching pulse modification-based method is proposed to compensate the dead-time effect within each SSS. Moreover, an SSS transition rule and the transition diagram are furtherly presented to avoid the dead-time effect between different SSSs. Consequently, both the output voltage delay and the unwanted voltage glitches that caused by the dead-time effect are avoided in the whole modulation range. Besides, a balancing strategy is proposed to balance the flying capacitor voltage based on the charging abilities of SSSs. The performance and effectiveness of the proposed modulation scheme are validated by both simulation and experimental results.