A Flexible Space Vector Modulation Scheme for Cascaded H-Bridge Multilevel Inverters Under Failure Conditions
Hongjian Lin, Mahmoud Mehrabankhomartash, Fan Yang, Maryam Saeedifard, Jiangpeng Yang, Zeliang Shu
Abstract
Space vector modulation (SVM) is a mature modulation scheme, which is widely used for voltage source inverters. In this article, a flexible online SVM scheme is proposed for a cascaded H-bridge multilevel inverter (CHMI) under short-circuit and open-circuit switch as well as cell failure conditions. The proposed scheme directly calculates all the active redundant switching states and the dwelling duty cycles of the three space vectors enclosing the reference vector for a CHMI such that balanced line-to-line voltages and currents under failure conditions are generated. Accordingly, the resultant switching sequences are determined to meet any specific requirement, e.g., even-order harmonics elimination and minimization of switching losses. Furthermore, in order to reduce voltage stress on the semiconductors under short- and open-circuit switch conditions, an equal power distribution criterion is introduced. The proposed SVM scheme is fast and independent of the number of levels. Experimental results are presented to demonstrate performance and effectiveness of the proposed scheme.