This paper proposes a hybrid converter for medium-voltage six-phase machine drive systems that mixes the operation of a traditional two-level voltage-source inverter and the modular multilevel converter (MMC) to enable operation over a wide frequency range. Topologically, the proposed converter consists of nine arms resembling two sets of three-phase MMCs with three common arms, yielding a nine-arm MMC with a 25% reduction in the number of employed arms compared to a traditional dual three-phase MMC. The multilevel property of a standard MMC is emulated in the proposed converter, however on a two-level basis, resulting in a stepped two-level output voltage waveform. The proposed converter has a reduced footprint with advantages of small voltage steps, modular structure, and ease of scalability. Further, it is able to drive high-power six-phase machines within low operating frequencies at the rated torque. The operating principle of the converter is elaborated, and its modulation scheme is discussed. The features of the proposed converter are verified through simulations and experimentally.
|Title of host publication||2018 IEEE Applied Power Electronics Conference and Exposition (APEC)|
|Place of Publication||Piscataway, N.J.|
|Number of pages||8|
|Publication status||Accepted/In press - 18 Oct 2017|
|Event||2018 IEEE Applied Power Electronics Conference and Exposition (APEC) - San Antonio, TX, United States|
Duration: 4 Mar 2018 → 8 Mar 2018
|Conference||2018 IEEE Applied Power Electronics Conference and Exposition (APEC)|
|Abbreviated title||APEC 2018|
|City||San Antonio, TX|
|Period||4/03/18 → 8/03/18|
- medium voltage
- modular multilevel converter
- nine arm MMC
Diab, M. S., Adam, G. P., Williams, B. W., Massoud, A. M., & Ahmed, S. (Accepted/In press). Quasi two-level PWM operation of a nine-arm modular multilevel converter for six-phase medium-voltage motor drives. In 2018 IEEE Applied Power Electronics Conference and Exposition (APEC) Piscataway, N.J.: IEEE.