Extended Operation of Cascade Multicell Converters Under Fault Condition

• Published in: IEEE transactions on industrial electronics (1982) Vol. 56; no. 7; pp. 2697 - 2703
• Main Authors: Lezana, P., Ortiz, G.
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.07.2009; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Balancing; Cascades; Converters; Electric potential; Fault tolerance; Faults; Leg; Modulation; Multilevel; multilevel converters; Photovoltaic cells; Pulse width modulation; Pulse width modulation inverters; STATCOM; Switches; Switching converters; Topology; Voltage
• ISSN: 0278-0046; 1557-9948
• DOI: 10.1109/TIE.2009.2019771

Multilevel converters are an interesting alternative for high power drives, due to their good quality output signals. Despite their advantages, the large number of components required increases the fault probability. Among the multilevel topologies, the cascade multicell converter presents advantages when operating under internal fault conditions, due to its high modularity. Previous works proposed to compensate the unbalanced operation due to a fault by changing the canonical fundamental output phase shift to precalculated angles, depending on the fault condition. This solution assumes that, if the maximum output phase voltage on each leg is used, the maximum line-to-line voltage will be at a maximum as well. This paper shows how this assumption is not always valid and presents the optimum angles and modulation indexes that must be used in order to obtain the maximum balanced load voltages.