This paper introduces new controls for the cascaded multilevel power converter. This converter is also sometimes referred to as a ldquohybrid converterrdquo since it splits high-voltage/low-frequency and low-voltage/pulsewidth-modulation (PWM)-frequency power production between ldquobulkrdquo and ldquoconditioningrdquo converters respectively. Cascaded multilevel converters achieve higher power quality with a given switch count when compared to traditional multilevel converters. This is a particularly favorable option for high power and high performance applications such as naval ship propulsion. This paper first presents a new control method for the topology using three-level bulk and conditioning inverters connected in series through a three-phase load. This control avoids PWM frequency switching in the bulk inverter. The conditioning inverter uses a capacitor source and its control is based on compensating the real and reactive (P-Q) power difference between the bulk inverter and the load. The new control explicitly commands power into the conditioning inverter so that its capacitor voltage remains constant. A unique space vector analysis of hybrid converter modulation is introduced to quantitatively determine operating limitations. The conclusion is then generalized for all types of controls of the hybrid multilevel converters (involving three-level converter cells). The proposed control methods and analytical conclusions are verified by simulation and laboratory measurements.
S. Lu and K. Corzine, "Advanced Control and Analysis of Cascaded Multilevel Converters Based on P-Q Compensation," IEEE Transactions on Power Electronics, Institute of Electrical and Electronics Engineers (IEEE), Jul 2007.
The definitive version is available at https://doi.org/10.1109/TPEL.2007.900471
Electrical and Computer Engineering
Keywords and Phrases
AC Motor Drives; DC-AC Power Convertors; Invertors; Power System Control
Article - Journal
© 2007 Institute of Electrical and Electronics Engineers (IEEE), All rights reserved.