A new type of multilevel inverter is introduced which is created by cascading two three-phase three-level inverters using the load connection, but requires only one dc voltage source. This new inverter can operate as a seven-level inverter and naturally splits the power conversion into a higher-voltage lower-frequency inverter and a lower-voltage higher-frequency inverter. This type of system presents particular advantages to Naval ship propulsion systems which rely on high power quality, survivable drives. New control methods are described involving both joint and separate control of the individual three-level inverters. Simulation results demonstrate the effectiveness of both controls. A laboratory set-up at the Naval Surface Warfare Center power electronics laboratory was used to validate the proposed joint-inverter control. Due to the effect of compounding levels in the cascaded inverter, a high number of levels are available resulting in a voltage THD of 9% (without filtering).


Electrical and Computer Engineering

Keywords and Phrases

23 KW; Cascaded Inverter; Naval Surface Warfare Center Power Electronics Laboratory; Cascade Control; Cascade Networks; Cascaded Inverter Control; Dc Voltage Source; Invertors; Joint-Inverter Control; Load Connection; Multilevel Inverter; Multilevel Inverter Control; Naval Ship Propulsion System; Power Quality; Three-Level Inverter; Three-Phase Three-Level Inverters

International Standard Serial Number (ISSN)


Document Type

Article - Journal

Document Version

Final Version

File Type





© 2004 Institute of Electrical and Electronics Engineers (IEEE), All rights reserved.

Publication Date

01 May 2004